Here are some comments you have made.

We only publish comments with the author's permission.

From: Philip Gomm Date: Wednesday, 8 March 2023 at 10:26 To: Brian Sowter Subject: Thank you, 9525 interstage Tx

Hi Brian, A few months ago you kindly gave me some advice on re-setting the gap on the 9525 Tx for use with the type 26 triode pre amp. As you said re-gapping was very simple, I suppose I thought the varnishing would stick the laminations together, but it was fine.

I experimented with a range of spacer materials, silicone, copper and aluminium and measured the inductance, in the end I just cleaned off as much of the residual adessive as I could with magic sponge, but a very thin smooth layer remained. I applied a bit of hard bees wax and clamped the laminations tightly. I checked for core saturation at low frequency by measuring the symmetry of the distortion. I have done two pairs of Tx now, both very successful. I didn't bother with the wax on the second as more adessive remained.

With a bit of resistor loading manged to get frequency response down to about 18Hz @-3dB. The only problem I had was voices could sound thin on some CD's, and bass a bit light. I then tried a Zoble network, but not the usual values, (to prevent ringing) I selected a resistance of 2rp (15K) and a 1 micro F cap, so that the impedance on the secondary started to increase at frequencies below about 100Hz, to compensate for the inductance. The frequency response at the bottom end changed far more than I expected, previously there was a gentle gain slope down from 150Hz down, than quite a fast roll off from 50Hz

Frequency response now 12Hz to 70Kz at the -1dB point. Distortion 0.05% @1kHz.

Sounds absolutely stunning, masses of low level detail, nice even tonal balance, firm accurate bass. just sounds lovely and musical. So I am very pleased.

I have many friends around to listen, one a professional hifi reviewer. All consider, it is one of the best, if not the best they have ever heard. I now have requests to build another two, one for the hifi reviewer. So I hope to put in another order in for 4 off 9525 very soon

I would be more than pleased for you to put my comments on your website, it would be nice to think it may encourage others not just to purchase your products, but to be ambitions and experiment. I get so much pleasure from building kit and undertaking such experiments, and without companies like yours and the support that comes with it, it would be very difficult to say the least.

Thank you again. All the best Ted

From: []

petrol can RCA
Sent: 13 February 2020 05:31
To: 'Sowter Transformers'
Subject: RE: 9830 RCA BA-6A Compressor Inter-stage Transformer

Hi Brian,

I knew that the black tar like substance was in there as I had drilled a pilot hole and extracted some a few days ago. A bunch of other techs that I connect with had theories on how to get it to loosen up but most of these were wrong. I will list some for your reference, these were all tested with a small sample of the black tar like substance first:

  1. Boiling in water: just not hot enough
  2. Baking in an oven: I do not want to try this in my domestic home oven and I don’t have a workshop oven, it will probably work well and will be fast
  3. Soaking in methylated spirits: does nothing
  4. Soaking in Shellite (Shell lighter fluid): does make the black stuff go gooey but is not impressive
  5. Soaking in Kerosene: makes the black stuff go gooey but is not impressive
  6. Soaking in petrol: easily the best that I have tested so far. I have now soaked the original transformer can in petrol for 48 hours and I still cant get the original transformer out. I will soak for 7 days and see what happens.

The photo shows the original transformer in its can filled with petrol and covered with plastic. I have this sitting in my box trailer in a spot where it can do no harm if it happens to ignite.

Regards, Warren Huck, Hux Electronics, 61 429 065 176

Brisbane, Queensland, Australia

From: Alexei Chebotarev []
Sent: 23 September 2019 05:00
To: Sowter Transformers
Subject: Re[9]: Despatch details & invoice

     Dear Brian,

I have installed 1465 transformers to my Tentlabs player these days..  it took more than year occasionally!

I am happy to let you know the transformers are so beautiful!  They are so good technically and musically.
I have in compare some very expensive players of my friends.

I am very grateful for the product.

Среда, 14 марта 2018, 0:27 +08:00 от Sowter Transformers <>:

From: Don Voth <>
Sent: 30 July 2019 14:28
To: Brian Sowter <>; Sowter Transformers <>
Subject: Re: Fwd: Re: Altec Mic PSU

Hi Brian
I need 3 more of these custom transformers. Also you can make note that you now have a transformer that works with the Altec M52 Mic.
The customer has compared this mic with your transformer to a Nuemann and a Shupps. The Altec wins hands down.
This was the Transformer in my last order that we got with PCB pins NOT wires. I think it is part# 1584c but I am not sure about that. Please double check to make sure we get the right one.
Do you need may plastic again or do you have that on file.
THANX Don Voth
341 Hazel Dell Ave
Winnipeg ,MB R2K 0R1

From: Lincoln <>
Sent: 04 December 2018 12:44
To: Brian Sowter <>
Subject: Re: Custom transformer inquiry

Hi Brian,

I just thought I’d send a couple of pics of the Sowter 1200 transformer with some freq response measurements (and very rough phase judged from scope) I just did. The transformer was a squeeze but I think it’s going to be just fine. The gain seems to be 7dB higher than when using the old transformer but again, this will be tweaked in due course.

I now have the 17 working channels (10x UA1008 and 7x UA1016) that I need to complete this wonderful console. Thanks again for making such a rare and wonderful product!



Sowter12001200 frequency response

From: Paul Briggs <>
Sent: 24 October 2018 10:09
To: Brian Sowter <>
Subject: Re: RE: FW: 1090 1:2 Moving Magnet Cartridge Transformer

Hi Brian
"I currently run a Shure V15VxMR cartridge. It's a great performer but has a fairly low output for a moving magnet (3mV). As I am using a fixed gain valve phono stage in to a passive pre-amp, this meant the volume had to be be near maximum (the knock on effect of which is that the parallel resistive load presented by the passive volume control and my power amp, to the phono stage, is close to its minimum value - not ideal!). With the 1090 transformers fitted not only was this two fold issue remedied (while maintaining a superb frequency response), but the noisefloor of the phono stage was much reduced. I cannot recommend them highly enough."
Sent from my Sony Xperia™ smartphone

From: Lars Erik Axelsson []
Sent: 23 July 2018 19:56
To: Sowter Transformers
Subject: Re: Order Number: LA247610000441

Hello Ruth,
just wanted to tell you how extremely satisfied I am with the 1480s I purchased from you. The sound is amazingly crystal clear together with my DL-103R. It gives a sound stage I had never expected. The sound is better than I had ever imagined, this cartridge and these transformers are made for each other.
I attach some pictures of the SUT

1480 Cartridge SUT transformer

From: Ho Ngo <>
Sent: 23 May 2018 04:13
Subject: Re: RE: Sowter 8423S transformer

Dear Mr. Sowter,

I have built a Stax earspeaker amplifier with 845 tube at 600V using the Sowter 8423. These transformers are excellent giving fantastic soud through the Stax. Attached is the amplifier.

Thank you for your support.

Ho Ngo

Stax headphone amp

From: Francis Woodhead <>
Sent: 07 April 2018 12:53
Subject: Re: please advise tx 1475 - THANK YOU!

Hi Brian,

I just wanted to thank you for your advice and have resolved my issue with my thorsten leosch adagio dac using 1475 transformers.
The result is pin sharp resolution and i am happy and astounded by the result.
I love the philips 5687 in srpp and sold my kt88 amp regretably which used these driver valves so this is a tremendous result for me.
Thank you for your hard work and patience in helping me resolve this and i am  one happy customer.
I have 8347 tx on the iv conversion of the tda1541a i used from a arcam cd5 using motorboat battery supply to keep jitter level low and use an tuning air capacitor to get the tda541a oscillator to lock on.
Thank you for helping me with my project.
Yours sincerely,
Francis Woodhead

From: Andriy Volikhovskyy [
Sent: 22 July 2015 17:11
To: Brian Sowter
Subject: Re: Transformer for DAC WM8742

Hi Mr. Brian,

Thank you very much for your advice. I've just ordered 3575's, so I'll let you know how it sounds when project will be done. Honestly I never doubt your advice. Before I ordered many transformers from you and so far all amplifiers sound very good.

My friends admit it too. 

Best regards.


Dear Brian

I received my custom power and output transformers at the end of April and they looked superb.  After many hours of work I have finished the prototype of my new mono block valve amplifiers.  My design uses a 6922 long tailed pair at the input directly coupled to a 6SN7 differential pair second stage and then via a coupling caps to individual 6SN7 cathode followers for each of the four KT120 output valves.  The output valves run at about 530V and an idle current of 70mA.  No overall feedback used so far but I have enough gain for about 6dB if I want it later. 

The results are fantastic, quite the best sound I've ever heard, even into my monitor audio BR2 test speaker and significantly superior to my previous amplifier using Amplimo transformers.  I'm getting max 60W output in triode connection and 50 W output (my design target) at 0.9% THD without overall NFB.  I've not measured Rout yet but the bass is powerful and very well controlled.  Mids and highs are wonderful.  My wife was in tears at our listening test yesterday.

Sowter products are more expensive than most of the competition but the best value for money I've seen so far - I would urge anyone to spend the extra money.  A friend may be asking me to make a 300W bass guitar amplifier and if he goes ahead I shall certainly be using your transformers.

Regards David Wellings

From: Peter Farrow []
Sent: 13 June 2014 10:44 AM
To: Brian Sowter
Subject: Thought you would like to know

Dear Brian,

my separate screen winding transformer arrived today so I will test it shortly.

I thought you would be interested in the previous transformer you supplied, which tests just about text-book perfectly in my amplifier design for frequency response at 50W of power (see attached).

To say I am delighted is an understatement

Thankyou very much


Hello Brian

Thank you for a splendid input transformers 4383!
I got very effective, linear and simple driver. It is impossible to have a powerful driver of one cascade 6SN7 and a gain app. 80 .  

We listed my new amplifier yesterday, the people said  "Super! " You can see a right monoblock on att. photo. 

Best regard, Aleksandr

Sat, 23 Nov 2013 04:29:01 -0000 от "Brian Sowter" <>:


4383 customer comments

From: Andrew Blumfield | Personal []
Sent: 05 April 2014 7:32 PM
To: 'Brian Sowter'; 'Sowter Transformers'
Subject: RE: Transformer for unbalanced to balanced audio

Hello Brian, Ruth,

I wanted to write to say just how delighted I am with the 3575 transformers with OCC wire.  First of all the transformers arrived well ahead of expectations.  And with them installed, my stereo is now silent when quiescent - with the earth loop broken and with the cheap temporary transformer replaced, the sound is out of this world.  Dynamics and detail now combine with a beautifully sweet sound to vocals - a better sound than this system has ever delivered before.  Thank you so very much for a wonderful product.  I will be delighted to recommend to anyone who cares to ask.

Very best regards,

Andrew Blumfield


From: Robert []
Sent: 02 September 2012 11:01
To: Sowter Transformers
Subject: Re: Invoice and despatch details

Dear Sir/Madame.

Invoice number 39134

Thank you for the safe delivery of my transformers and the flexibility on delivery.

Sorry for my slow reply but I needed some time to listen to the transformers.

First I would like to thank Brian for the information via telephone he was very patient with me in his explanations and that the 1:20 do work very well in my system.

I feel I must comment on the OCC wire, you should make more of this on your web site it has a very positive effect on the transformers, it is hard to explain but it seems to lift it above the normal wire, better highs, better mid’s and better at the bottom end I feel it is well worth the extra money I paid for the OCC wire.

I am very happy with the transformers supplied and can highly recommend your services.

Many thanks Robert Gardiner.

-----Original Message-----
From: Jerry Zhang []
Sent: 30 August 2012 9:59 PM
To: Brian Sowter
Subject: Re: transformer brackets
MC Phono transformer in box with XLR
Hi Brian

I got the 9580s,  have them wired with XLR (floating as you suggested), ground connects to my phono stage, and the result is simply amazing, no hum at all, and the mc section of my $2000 phono stage got destoried by 9580, the sound stage, the inner detail, the tone... this was my first time trying SUT and I didn't know what to expect initially, but what I can say now is just wow, why didn't I try this earlier!

I am spreading words with my audiophile friends, thanks so much..

ps, it so easy to diy, it took me couple hours to have everything ready.. doesn't look pretty at all but the sound quality is world class..

Best Regards


-----Original Message-----
From: Stanley Tang []
Sent: 27 August 2012 4:23 PM
To: Brian Sowter
Subject: Re: How to choose between 9570 and 8055

Hi Brian,

We received the two pairs of 9570 ordered and we are enjoying the music with 9570 in our phono amps now.  The result is stunning and we would you to know that we appreciate very much the quality of your transformers and the improvement it brought to our audio systems.

Thank you!

Stanley Tang

-----Original Message-----
From: Arthur Lowery []
Sent: 19 August 2012 1:30 PM
To: Brian Sowter
Subject: Fwd: Photos of Finished Valve Amplifiers

Dear Brian

Here are a couple of pictures of the finished pair of "regulated" Leak Stereo 20's I built with Sowter U082 transformers.

Heavy beasts, but they do sound good.

If you want to stick them on your webpage, then that's OK, but I am sure your customers have made prettier amplifiers than mine!

Regards Arthur

Leak Stereo 20

From: Юрий Тулаев []
Sent: 13 March 2012 8:46 PM
To: Brian Sowter
Subject: Sounding of the Sowter transformers

Hello Brian!
Sounding of the Sowter transformers.
I received the 9055 DAC output transformers in 2009. I introduced its to myself designed DAC. Main chip is AD1853 produced by Analog Devices. Input interface of chip is isolated by digital couplers. Output stage contains simple passive none feedback I-V converter with low resistance. The circuit has special DC zero schematic. The load of circuit is 9055 Sowter transformer. And the load of 9055 Sowter transformers is 6SN7 valve (6H8C in Russian version, where letters H and C comes from Russian alphabet and has Latin equivalents as N and S). In my hands: 6SN7 by Golden Dragon (New Production, made in China), 6SN7 by Philips (New Old Stock) and 6H8C produced by Moscow Valve Factory in early of 1953 (New old stock too) with transformer load. 6H8C is a real device from Stalin's era!!! It seems to me, the first place goes to Golden Dragon, the second place goes to Moscow factory and the third go to Philips. Sorry, the Philips has the poorest sound. So, impression of hearing. It’s the great, outstanding sound!  It deliveries an emotions, an energies of source. You are listening of jazz, vocal, rock, piano, contrabass, guitar, the great symphony orchestra with single results. It’s the perfect and outstanding sounding. It’s a life! You feel, like you visiting this concert, your place in anywhere in concert hall. It is very living! You want hearing once and once again! Don’t stop music, don’t turn off the system!  One of the components is 9055 Sowter transformer! Other information about my sound system: CD driver is Philips CDM12 mechanism. CD driver contains the special myself designed clock oscillator. It based in two quartz crystals and produced extremely very low phase noise. Main amplifier is Accuphase E-405. It loaded by very special myself designed acoustics. This acoustics contains the woofer produced by ScanSpeak. It placed to closed box without any bass “improvers”, such as bass reflex, transmission line and etc. It established pure, natural bass. For mid and high range I used the Lowther DX45 driver in separate box. Woofer is works up to 150 Hz and after this the Lowther takes all other range. 
Yury Tulaev, Saint-Petersburg, Russia.

07 марта 2012, 21:45 от "Brian Sowter" <>:


Sent: 25 February 2012 20:12
To: Sowter Transformers
Subject: Re: Mr Staton - Invoice 38614

Dear Ruth,

Thanks for the diagram. I’ve now got the transformers installed in my hifi being fed by an Ortofon Per Windfeld cartridge. The sound is absolutely outstanding – dynamics , realism first rate. I’m going to have the transformers cryogenically treated shortly, i’ll let you know what i think.

Best regards

Mark Staton


Sent: 02 October 2010 5:31 PM
Subject: Sowter Pultec Transformers


Hi Brian,

I thought you might be interested in this post I made on the Prodigy/DIY forum about your transformers:-

I'm in the process of building a Pultec EQP-1A, with the layout designed and built from scratch.

I made the power supply and make-up amp first and tested it before going on to the passive section (I've already breadboarded that ok).  I've used a Sowter 9330 interstage and 9530X output iron.  I used a Chinese 12AX7 from RS and a 40 year old used Brimar ECC82 for the output (it had already seen 30 years use in my HIFI !  Voltage balance of the tubes was within 2%.

I wired it old school with a heavy busbar for earth and point to point without using turret boards (don't like all those wires picking up hash.

I measured +28dB into 600 ohms load before visible clipping, that's 20V!  The amps output Z worked out at 57 Ohms.

The gain of the amp was 17.3 dB not including the interstage.

What astonished me was the frequency response -0.2dB at 10Hz then flat till 20kHz where it was -0.2dB it was -0.56 at 30KHz, -0.9 at 40KHz, -1.3dB at 50kHz, -3.5dB at 100kHz and -15dB at 200kHz.

I used a 1.5nF/9.1k zobel across the interstage which gave the best square wave performance and the above figures.  There was no hint of instability and no need for caps across the grids of the ECC82's either.

I think the famous low-end on the Pultec must owe a lot to the amp, and the top end of the Sowter iron speaks for itself.

I thought you might like a bit of positive feedback!
all the best

David Pendrill
Head of Research & Development.
Phosphor Technology Limited.
Norton Road.

Brian Sowter comment: We use a part Mumetal core for the output transformer.  This means we get a very high inductance which probably improves the LF cut off relative to the original also.  It also means we can also use fewer turns on the transformer which improves the HF response.

package for MC phono cartridge transformer

From: Steve Lawrence []
Sent: 07 June 2010 19:42
To: Sowter Transformers
Subject: Re: Mr Stephen Lawrence - Invoice 37274

dear Ruth,
Thanks for the invoice.I was delighted to receive your transformers in the post on Saturday. Having prepared a case and sockets in advance I set to work and did all the cabling and soldered joints the same day.The result looked great, finished in glossy dark blue with a silver name plate, but more importantly I have now carried out listening tests.So please pass this on to your technical team.
 I am using it with my usual fully balanced and adjustable(English) phono stage, with the amplifier gain set to suit  5mV and with appropriate loads (which I can vary from 46k down to 6k3). My earthing connections proved correct first time and are absolutely silent - adding nothing to the preamp background noise. So I did get it right in a fully balanced scheme with XLR connections ! The short captive output cable is made from the transformer secondary leads as a twisted pair, a  'neutral' wire from the headshell, (as used in the Graham tonearm lead), both in a braided earthed screen, finished with an XLR male plug. 
I am so pleased with the results.Compared to using a lot of  gain (even in a very high quality* phono stage), I find the response incredibly smooth and well detailed, but cleanly extended to very high frequencies. This has exceeded my expectations and I am so glad that I followed my instincts that transforming a moving coil output was exactly the way to get the most from this type of cartridge. It is an Ortofon Kontrapunkt B, and I have saved myself the expense of upgrading to a yet more expensive type ! Your transformers represent terrific value as an upgrade.

PS * I recently used a Chord Symphonic fully balanced phono stage at home and I believe that using your transformers has bettered that.

From: []
Sent: 23 November 2009 12:28
To: Brian Sowter
Subject: Gianpaolo Lanza - 8347 DAC transfomer

Dear Mr Sowter,

I'm ready to give you the FFT results about the parallel of two TDA1541A and your output transformer 8347c. The transformer was loaded with 33Kohm and the TDA1541A with 18.2ohm. The output DAC current with this load is 7.5mA while the output voltage is 38mV peak to peak (13.2mV rms). At the secondary is present about 180mV rms, surely not an high value but enough for drive a good valve preamplifier.
The sound is amazing, there is air among the instruments and the image is much deeper than the DV7600 used like a test, the bass are incredible fast. I'm really satisfied!!!
In attach you can finde the pdf file with the FFT results, is important to note that the THD is a little bit higher in the TDA1541A against the DV7600 by Marantz, but the shape is absolutely better, in fact the 3rd harmonica is lower in TDA1541A. See the Pdf and the notes over the pages.
Best regards and compliment for your product!!!!


FFT for 8347 DAC transformer

Dear Brian
Your new custom Marshall DSL 50  output transformer is fooking great. The amp has so much more chime in the clean chords as well as giving a noticable increase in the low frequency performance for down tune dirty stuff.
No longer does it sound strangled and thin at high volume, it just wails now at all frequencies so feedback is much more controllable with good pickups and all the harmonics are there now real strong.
I am biasing it at 40mv instead of the marshall spec at 45 because it has even too much snap at 45 and 40 just softens its power delivery enough for plenty of edge in the tone but not too much.
Only improvement to the kit would be to add another 2 inches to the primary leads to make cable routing very slightly better.
Thanks for all your help its now made an amp that is finally really worth putting a mic in front of, as the old JCM 800 used to eat it for breakfast, but not anymore.

Regards.•:*¨¨*:•. ¸¸.•´¯`•.Mark Fairfax-Harwood, Engineer Springvale Studios __________________________________________________________

From: Sergei Klimanski []
Sent: 22 December 2008 00:02
To: Brian Sowter
Subject: Re: request SE 4613

Dear Brian,

Finally I completed my SE amplifier ( tubes are Aa Valvo - 4613 Pope ) with output transformers as per your advice, and with your 8920 transformers as input. Frankly speaking, I have got best sounding amplifier I have ever heard. 
Best wishes on Chrismas and sucsessful 2009,
With many thanks,

 Sergei Klimanski

From: []
Sent: 14 November 2008 19:06
Subject: rich walt ch

All  qualify for that Christmas Turkey.
Congratulations with those ECL82 transformers. Another top notch bit of winding engineering. Some pics enclosed and performance way beyond expectations.
Circuit not based on Mullard version as this showed far higher thd with higher noise floor but a fixed bias and a
down-sized driver variant sim to the 150W amp design I used. Output stage distortion cancellation practically perfect.
20dB global nfb used with transformer screens on 40% taps. With 20% distortion doubles.
Sq wave optimised using anode-g2  soft snubbers. 1nF +2k2 Freq resp -3dB point around 43KHz at 7W.


ECL82 Transformer


From: kees van de wiel []
Sent: 15 October 2008 21:33
To: Brian Sowter
Subject: RE: Kees van de Wiel -Moving Magnet Transformer

Hello Brian,
I am glad the report was of help to you.
Of course you can put it on your website.
I can say without hesitation that transformers by Sowter deliver very high performance and have an excellent price/performance ratio. The possibility to order custom products is a service you don't really see with other quality manufacturers. 
For instance, I previously used a couple of Tango FE-50-5 OPTs on my 6B4G amps. Transformers of high reputation, sure, but somehow they never truly convinced me. Then I custom-ordered your type 1046S and everything fell into place. The Sowters were clearly superior in every department you care to mention: bandwidth, resolution of fine detail, correctness of timbre, bass extension and an overall very relaxed presentation. Whereas with the Tango's I often had the feeling that the music was straining to get through. 
I hope Sowter as a small independent company with such history will be here for many years to come, supplying the audio community with their excellent products.
Best regards,
Kees van de Wiel

From: michelemercatali@virgilio.
it []
Sent: 21 October 2008 13:21
Subject: sowter 9580 mc

Hi,I'm Michele Mercatali,

a few days ago I bought 2 9580 sowter,I would like to thank
you a lot because I'm very satisfied,they're simple amazing!

regards     Michele

Hello Brian

I built a Line amplifier with Sowter transformers   9335 and  9041.

Attenuator transformer is a dream, compared with even the best potentiometer.

In the attached image the detail of volume control.

Sowter TVC tranmsformer attenuators
Complete description of the amplifier on my website, at:

Kind regards

Giovanni Cornara
Via Aleardo Aleardi 14-2
35122 PADOVA

From: Jan Erling Veiset [mailto:]
Sent: 13 December 2007 09:44
To: Brian Sowter
Subject: Re: FW: 1036 Jan Veiset

 Hi Brian,

I'm now testing the unity amplifier and the trifilar transformer performs very well. The amps are basically built from the attached revision of the schematic and the front end is a common cathode + split load phase inverter based on E80CC.


Working conditions are 260V B+, 190V Bg2 (regulated) and –90V for the negative rail. The amp runs near to class B, biased with 4 x 10mA in the output stage.  Max power output was estimated to be about 30W and I measure the onset of clipping at ~15Vrms into 8.2R (~28W)


Global feedback is kept low, about 10dB, but there are no problems to apply more feedback to get even better technical results. Personally I am not a big supporter of global NFB, but used in proper amounts it does good things.


With 10dB NFB I achieved these results:

Zo : 0.8 ohm

THD: 0.6% (30Hz, 1kHz, 10kHz, 25W Po) (2nd and 3rd harmonic dominant)

Freq resp: 10Hz -100kHz (+0/-0.5dB). –3dB at 230kHz.


With feedback there was no major peaks or dips in the frequency response. There was a small, low Q peak at ~100kHz (+0.8dB) but with 24pF in parallel with the feedback resistor the response turned out to be straight as an arrow up to 100kHz.  

The attached square wave is 30kHz, quite astounding for a tube amp.


All in all, this project ended up with the best frequency response I ever have seen in a tube amp with output transformer. Thank you for superb transformers!  


Best regards,

Jan E Veiset


Sowter type 1036 output transformer

Sowter 1036 output transformer response

Hi Brian

Just to let you know I installed the TVC today and the results are superb. This is like changing a major component in the system! The most obvious difference is the ease of the sound, the complete lack of hardness, grain, and edge, even on CD. I was already using a high quality Grayhill attenuator with Holco resistors, in a shunt arrangement in my passive, but your transformers have transformed the sound (sorry! but it's true...). The naturalness, dynamics and liquidity (not just in the midrange!) of the sound are staggering. And when things get loud, the sound does not harden or change, it just gets loud...

In my opinion every serious audiophile should hear and buy these TVC's, because a resistive volume control adds so many deleterious artefacts and subtracts so much subtle information, this is so blatantly obvious now. I am overwhelmed by the change. I expected a subtle improvement, not a transformation and huge improvement in sound in an already very high end system.


Mike Kontor
NotePerfect Loudspeakers
158 Galatea Road
Vic 3351
tel (03) 53428866


Date: 3 September 2007 13:07:00 BDT
To: Brian Sowter <>
Subject: 6AS7/6080 push pull output transformers

Hi Brian,

Just a note to say I installed the push-pull output transformers on Friday. They provide the perfect finishing touch to the retro 50s style 6AS7 amplifier I have been working on for the past couple of months.
There are a total of 5 pieces of Sowter ironware in this amp. A size P custom mains transformer, a pair of 3575 isolator/balancers on phase splitting duties and the pair of custom output transformers

What can I say? The output transformers have replaced a pair of Hammond 125Ds and have taken the performance of this amp to another level entirely! To talk about veils being lifted and instruments appearing from nowhere would be to fill this email with cliches. But it's perfectly true. Most people would be satisfied with this but even better is the full-bodied, clean, dynamic and effortless presentation these transformers give. No congestion at higher levels and zero listening fatigue.

6AS7 output transformers

Excellent service and turn around time too. Fantastic!

Kind Regards

 Steve Cresswell

From: Carlo Balestrazzi


Sent: Thursday, May 03, 2007 9:45 AM

Subject: A couple of Sowter transformers


Dear Sirs,

my name is Charles Balestrazzi, I live in Italy and am 47. It means that 30

years ago I saw an advertisement on "Wireless World" of your Company, and

decided to order a couple of your output transformers for EL34 PP, for my

home made amplifier. I was 19, now 47, as I said, and that amplifier has run

for 28 years without any problem, your transformers has given a pure warm

enjoyable sound ALMOST EVERY DAY of my life for 28 years. I've substituted

valves, resistors, diodes, capacitors, one choke, speakers, but your

transformers are still young. Friends of mine that possess tube amplifiers

are used to say that my one is particular, because it has got the force of a

push-pull and the details of a single ended.

I use general feedback, cum grano salis.

Thank you very much.


Carlo Balestrazzi


From: Luca Sfarzo []
Sent: 31 March 2007 21:49
To: 'Brian Sowter'
Subject: R: info about Sowter 8055 and Benz ACE cartridge

Hi Brian,

I am writing you this email after having bought some time ago (about 2months) a par of 9570 and after having put them to play for about 80 hours in a World Audio Desing Phono II DIY pre-phono.  

I have to say that it has been a very very fine choice buying and playing your amps; They are stepping-up a Benz ACE/SME3009S2 (rewired)/TD160 LP machine and the sound is really detailed, clear and, above all, they allow the system to give that ?live? sensation of being just in front of an orchestra playing the Beethoven 9th Symphony..

Least but not last they are very quiet; they add no hum at all and I find that it is a very remarkable feature.

You can find attached a jpeg of the work I did.

Next step could be trying some sowter transformers in my wad kat6550 power amplifier...not so far in the future.

So thank you for your support.

Best regards,

Luca Sfarzo Italy

Sowter MC phono cartridge transformers

Hi Brian,

I just installed the new transformer in the RCA BA6A and the unit is working excellently now.  I was able to get a perfect balance out of the vari-mu tubes.

Thanks for all your help.  I tried to get the original out of the can but gave up on all that black wax goo holding it in there.  I ended up using washers to clamp the new one to the edge of the empty hole in the chassis where the original was. 


Chip Verspyck

Tech It Out Inc.
70 Upperhook Rd.
Rhinebeck, NY 12572
845-876-2653 ext.6

From: Lukasz Fikus [] 
Sent: 26 December 2006 00:16
To: brian last; Brian Sowter
Subject: Re: Sowter DAC transformers

 Dear Sowter,

 I hate you for what you have done to me. Your transformers are so  addictive
 that  I can't imagine any listening without them. The musical effect is mind blowing.
 I use them to connect the DAC chip directly to a high-end tube output.
 I tried them in Copland 289 (parallelled BB PCM63K), Shanling T200  (balanced
 BB  PCM1738), Grundig 9009 (paralelled TDA1541S) and Kenwood 7090 (8 BB 
 PCM1702 in  balanced mode). In all cases the result is phenomenal. Never mind the DC  R 

 Thank you.

 Lukasz Fikus

-----Original Message-----

From: Jan Erling Veiset
Sent: 03 September 2006 16:52
To: Brian Sowter
Subject: RE: FW: (Fwd)Jan Erling Veiset - Quotation for transformers. JE-PSE6550-107006

Hi Brian.
I have now finished the wiring for one amplifier and the results are quite impressive. This amp can move mountains; it s very powerful and clean sounding.
I have documented the performance and I've got a full wiring diagram on my web site. Some key results are 45 Watt rms in UL, bandwidth from less than 10Hz to over 70kHz (-3dB at 10W Po) and low distortion and low output impedance. Your OPTs make some very nice 10kHz square waves, most impressive, superb transformers!

Sowter power output transformers in valve amplifier

Best regards,
Jan E Veiset
N-6600, Norway




From: "gianni cornara"
Send reply to: "gianni cornara"
Subject: Output Transformer U072

Date sent: Tue, 25 Apr 2006 18:55:46 +0200

Dear gents,

I completed all tests on my guitar amplifier which utilizes a U072 OPT.
I am very very satisfied!! Thanks. The description is on my website

Kind regards
Giovanni Cornara

Via Aleardo Aleardi 14-2


Sowter 9545 DAC interface transformers

From: "peter carmichael" <>
To: <>
Subject: 9545 Transformers
Date sent: Fri, 17 Feb 2006 09:33:53 -0000

To all at Sowter Transformers

I want to say how pleased I am with the two Sowter 9545 DAC Interface Transformers you supplied me with.
I have fitted them to a Denon DVD-2900 player with the following modifications.

a) Audiocom Superclock 3 with power supply.

b) Audiocom Invisus regulators for 3.3 volt supply.

c) Added an extra Burr Brown DSD1792 DAC to convert the main two channel digital audio signals.

d) Used the two Sowter 9545 transformers to provide a new two channel audio output from the new DAC. The circuit is basically that of the DAC Passive Output Stage described at I have added some circuitry to reduce the DC through the transformer primaries.

e) Added a new analogue analogue power supply with Walt Jung super regulators to feed the analogue supply pins of the new DAC and the DC reduction circuitry. The DAC design described at was useful here.

The sound from the modified player has improved dramatically. So dramatically in fact that I have had to change my ideas about the audio sound quality available from digital sound sources, especially penny plain CD. Vinyl disc replay now seems a poor relic from the past.

my very best regards

Peter Carmichael


From: Date sent: Wed, 07 Dec 2005 15:44:28

Subject: THANK YOU


Hello Ruth,

Just to inform you that the parcel has been delivered.
Thank you very much indeed for your immense cooperation on this rather small order.

Its been a great experience dealing with SOWTER.Very few companies can manage good quality andbang on time delivery these days.

Convey my gratitude to Mr. Sowter and Mr. Brian Last.

Best Regards

Shivraj Singh.

Dear Brian,


A little bit later than it should have been, but the result is real proof and the reactions are very positive!

You can change the settings from the good old Fairchild to any other good working type of tube limiter/compressor with still some special features, which can be very useful in the studio.

The A.G.C. is a 3 stage fully balanced tube circuit with the original variable µ tubes, no solid state.


And last but not least is the quality of the special audio transformers, but I know now, I have not to care about that at all!! They are perfect.


an lang="EN-GB" xml:lang="EN-GB">Kind regards to you and your crew,


Jean Audier .


Sowter transformers in pro audio equipment

From: y.mahe []
Sent: 07 September 2005 12:14
To: Brian Sowter
Subject: message from Yannick Mahé about 9395 attenuator

Hello Brian,

I tested the 9395 "step up" attenuator connected directly on a AD1853
convertor. ( on the +12dB tap ).
I  connect it on a biamp high sensivity system ( the Grégoire Marlot
system, a very audiophile friend ).
A 38cm Supravox field coil bass speaker with a hybrid amp, and a Beyma
CP850nd 115dB mid/high horn on a 45 triode SE amp.

It sounds really good !  The transparency seems perfect.

So,  the idea is very nice....

best regards


 From: aronsson [

 Sent: 23 February 2005 19:50

To: Brian Sowter

 Subject: Thank you!

Thank you Brian!

I ordered a custom mains transformer and a pair of plate chokes to my Quad amps.

Your build quality exceeded my expectations and everything was  professionally packed!

I'm very satisfied with your service!

Best regards

Pontus Aronsson,   Sweden

Date sent: Wed, 23 Feb 2005 23:46:55 +0000

Subject: Re: Martin Thain - order

From: Martin Thain <>


Hi there,

Now got my transformers installed and working nicely. Sounding

excellent and getting better every day as they run in a bit more.

Quite a bit more of an improvement than expected - missing bass octaves have appeared, previously unintelligible lyrics can now be heard clearly, and my cat no longer feels the need to leave the room when I turn up the volume... Many thanks for an excellent product


I have attached some pictures of the 8995s 'in situ'

Sowter power transformers in audio amplifier

Sowter 8995 transformers in audio amplifier

From: AUDIER []
Sent: 25 November 2004 18:42
To: Brian Sowter
Subject: transformers

Dear Brian,  

I don' t know if you did the transformers all by yourself because they are 200% perfect. 

You was talking about decreasing the Freq. characteristic by making the ratio to big. I can tell you, with this quality of transformers there is enough room thanks very much, 

Regards to Brain Last (but not least) and Ruth who had so much patience.   I have no problem at all if you use the email I sent you, perhaps it has sense to add to it that it was very difficult for us to find someone who has still the knowledge to make this special transformers for pro vintage limiter / compressor because it is very critical.

till next order.

Jan Audier 

Fom: "Len Edwards" <>

To: <>

Subject: Re: G.L.Edwards - order

Date sent: Tue, 12 Oct 2004 18:00:50 +0100


Just to thank you for the transformers, received bang on the time
advised. They sound good with a few days "running in" and should
improve further with more use I suspect. Better than the James
transformers I've been using for the last couple of months by a
country mile.

Many thanks from a happy customer


To: "''" <>
Subject: Excellent Transformer

Date sent: Sun, 3 Oct 2004 14:06:07 +0100

I have completed installation of the 8983 and find them to be everything I was looking for. Powerful peaks remain perfectly clean (and very powerful). Bass is remarkable. Following is a note I posted on the SET portion of 

I continue to find the transformer's performance impressive. It facilitates the full dynamic capability of my 2A3 SET amp, making possible playback of orchestral and rock selections that sounded compressed with other transformers.

Leo Keightley


"It's a little hard to find reviews of the Sowter parafeed transformers, so I'll add to the small list.

I installed a Sowter 8983 in a 2A3 SET. I was able to purchase the 8983 (5KOhm primary) with a single 8Ohm output. I prefer a higher primary impedance than the 2.5KOhm that seems to be prefered by many for the 2A3. Until now I've been using Magnequest parafeed transformers.

I originally had a cobalt Magnequest (2.5KOhm in, 8Ohm out), but never really liked it. The variations in speaker impedance of my RF-7s and Chorus-IIs caused frequency peaks and gaps. I purchased a 5KOhm primary

(1.5Watt) Magnequest and the sound completely smoothed out. Great for quiet stuff, but some compression at higher volumes.

I selected the Sowter because it has plenty of power capacity (about 10 Watts) and the I/O impedances I found so successful with the smaller Magnequest.

The Sowter does indeed handle power peaks much better than the under-sized Magnequest. Extension is very good top and bottom, and detail is fine. I recommend the Sowter to anyone looking for a little more headroom than the 1.5 or 3 Watt Magnequests.

I've kept the Magnequests in the amp for quieter selections and can select either transformer with a switch (speaker cables have to be moved to alternate posts)."


From: John Lumsden [

Sent: 14 September 2004 16:53
To: 'Brian Sowter'
Subject: RE: U066 Size
Brian,  I thought you would be interested, received the U066(M) and connected it to the tube electronics (2 X KT88) in UL mode with cathode feedback and some overall feedback. After adjusting roll-off and feedback parameters I was able to achieve at 40W +/- 1dB 10Hz to 75KHz and <0.01% distortion at 1KHz with excellent phase margin for stability, we will reduce the overall FB for 0.05% as an added precaution. The square wave response at 1KHz is excellent with minimum ringing and zero overshoot. The transformer is excellent with a smooth rising response out of band. The amplifier is differential end-to-end and each stage was carefully adjusted for distortion.

The amplifier sounds superb also.

Best Regards,  John

From: Vinicio G. []

Sent: 10 September 2004 21:29

To: Brian Sowter

Subject: RE: Help in my stereo to mono design

Hello Brian,

I just received the 8920 (first I will try with the stereo to mono conversion). I just connected the 8920 to my SRPP 45 SE amplifier . Now I'am listening Turandot with Shutterland and Pavarotti from my turntable, I'm impressed. There are subtle details from the vinyl that where lost.  Now I switch to Gould on CD (playing Orlando Gibbons),my words are lost. Another change, to Blandine Verlet plying Froberger, a CD named "Froberger ou l'intranquilite'. Well, my english is not sufficient to express how the sound change, to express how I feel the music. The harpshicord seems to be in my room. Thank you very much for your fast an reliable service. Now it's time to try the 9335. Soon I will order it,

Best regards



From: bert []

Sent: 19 July 2004 21:33

To: Brian Sowter

Subject: Re: info wiring

thanks for the help with the info about the transformers! last week i was working on a film set in Belgium and the monitor from the lighting director made a 50Hz hum on the sound lines even after two days he did not want to believe it was his monitor causing a lot of trouble for the sound crew ! with al the transformers i found in the dump and earth lift and battery power and al the tricks ,we end up the week of working day and night it was a hell!!!! and that's why i want to thank you for your quick answer..... this is proffesional! and i apreciate this after a week of..f........ i am happy to see somewhere people take there job seriously!! thank you!!  location sound assistant

Sowter transformers on film set

From: Yury Gelgor []

Sent: 18 May 2003 05:11


Subject: Thank you for 9336s

Dear Mr. Sowter,

Your 9336 sound just great. I couldn’t even imagine that replacing of

Caddock resistor attenuator with such input transformer improved amp sound

so much.

You can use link to my site or amp schema any way you like. DAC is still a

project and not completed yet.

I DO appreciate your business.

Thank you

Yury Gelgor

Kansas City, USA

Date sent: Tue, 11 Feb 2003 11:08:49 +0000

From: "Carrick, M. (Mike)" <>


Subject: Big Thank you

Thanks for the mains tx and chokes, received Friday. I got the preamp finished over the weekend but only got as far as electrical checks on Sunday evening; anyway, last night I listened and wow, this beauty is *good* ... very, very good and musical. I know that power supplies are absolutely crucial in valve hifi. This preamp uses two stage pi filtering with the second stage split left/right channels .... hence my somewhat specialised needs, which you met; thank you! Rectification is by television damper diodes (6CJ3) which have *massive* voltage and current ratings, with extremely low voltage drop and 'clean' performance. I'm sure I'll be coming to you for more things in due course.


Mike Carrick

Sowter 6CJ3 transformers in valve amp

-----Original Message----- From: Aristidis Coumpas []
Sent: 31 March 2002 19:00
To: Brian Sowter

Dear Brian,

I know it took some time, but here is the result and I tend to believe that your "iron" (as the Americans say...) has a lot to do with the wonderful sound heard through my horns! Thanks again for all your patience and understanding, Aristidis

Sowter interstage transformers in tube amp

Dear Brian, I finished my preamplifier using pair 9335s and 3575s and it sounds fantastic! I wanted to share some photos with you. One is attached below and more you can find at:
Please feel free to use them as you wish.
Sincerely, Mirko Trifunovic Toronto, CanadaSowter TVC volume control transformers



.........Let me tell you also that I find your 'Neve transformers' absolutely amazing. I built a 1272 and I compared with the original. I did 24 tracks with both of them (2 songs, same one). When it was time to mix these songs, I found that the tracks I did with your transformers were adding to each other really better than the ones with the original Neve. The mix had punch and no 'fog'. Really nice ! Thanks for your help   De José Cédric <Sound engineer & Studio manager Au Pairon, 57 4831 Bilstain-Limbourg BELGIUM>

From: "Julian" <>
To: <>
Subject: Re: Order quote
Date sent: Sat, 2 Feb 2002 18:33:11 -0000

Dear Mr. Sowter.

The transformers below were used to make my phono amp (you
probably guessed this as I ordered two 8055's!). After some 
months of assembly and testing (and the rearrangement of some earths 
to minimise output hum) the amp is now complete. There is virtually
no hum at all at the output (about 7 mV peak to peak!). Not bad 
as the amplifier will produce 4 volts peak to peak from a 1 mV input
at 1 kHz. 

Both the four transformers and the two chokes (choke input power
supply ones at that) are absolutely silent as the grave - not a
vestige of hum can I detect at all. Of course all four transformers
perform exactly as per specification as well.

A very big "thank you" to you, the rest of the sales staff, and
particularly, to the person or persons who actually wound and
assembled the devices. They are truly superb. Without them the
amplifier would not have been as it is. Indeed it may not ever have
come into existence. It is good to know such skill exists.

When next I need some high performance transformers (and I will) I
shall come back to Sowter Transformers.

Your service is excellent and your products without equal.

Yours sincerely.

Julian Cooke - an extremely satisfied customer.

Dear Brian, 

Last week I enquired about the possibility of you supplying some transformer and choke shrouds in order that I might smarten up my old valve amplifier. The shrouds have now arrived, they're a perfect fit and exactly what I wanted. I have been so impressed with the friendliness and good service during my dealings with Sowter that I feel I must write to say thanks. I was beginning to wonder if I would ever find a source for the shrouds as I had drawn blanks with the sheet metal pressers that I had approached, and the response from certain other transformer manufacturers was a curt "We do shrouds for our own transformers only. Goodbye". Your service is all the more impressive given that my order was so tiny and almost irrelevant to your manufacturing. Even your protective packaging for transit in the mail was done very thoroughly. Please pass my compliments to all involved in my little order. You are a great company. 

Many thanks, Clive More

Dear Brian,

I have now installed the 2 8940 output transformers, that I got from you....and I must say that I´m more than very pleased with the sound of them.....I´m so glad, that I desided to buy these trannies from you, and they are as good as you said they would be....thanks so much Brian...

I`m looking forward  to buy more of these wonderfull output transformers from you...

What I will do right now is to take my little mic-preamp and do a lot of beta-testing with different engineers, and in different studio` in far It has been tested by Søren Mikkelsen of the top engineers here in Denmark...He has been booked for the next 3 weeks recording one of Dk. top selling  pop/rock artists...He will not return the beta ver. of this preamp before  He`s done with this gig.....*S*....a lot of the sound comes from your output tranni...I have tryed Jensen, Lundahl trannies, and the 8940 beat`s both...

Thanks so much again Brian....

Best regards

Peter Simonsen. Dk.....

Date: Sun, 19 Dec 1999 19:38:44 +0100
From: "D.J. van de Merwe"
Subject: email from Dick van de Merwe

Dear people at Sowter I build 2 Sowter 8347 transformers into my Denon 1000 minidisc-recorder which I also use as digital to analog converter. I am very pleased with the results. It sounds are so much better then with the build-in opamp analog output. My friend didn't believe his ears. What have you done, what have you done?............ Congratulations with such fine product. I will certainly use more Sowter transformers in the future! I am an enthusiastic Tube-amp builder myself.

Many greetings from the Netherlands,

Dick van de Merwe

From: "J. Claessens" <>
To: <>
Subject: Fairchild transformer question
Date sent: Mon, 14 Jun 1999 16:04:26 +0200

Dear Mr Sowter,

...........I also tested the Neve preamp I made with your transformers.
Though we didn't have time to do really good listening tests yet,
we can say we like it so far. I'm very happy there are still companies like yours,
with good old fashioned quality and modern specs.

Thanks !!

Dennis Claessens

From: "Graham Tricker" <>
To: "Sowter Transformers" <>
Subject: For the attention of Brian Last
Date: Fri, 19 Feb 1999 17:06:31 -0000

Dear Brian

This is just a note to say thanks for the transformers. I am very pleased with them. Its really great to deal with a company that's able to provide exactly what I need, taking into account my specific requirements.

Many thanks again. Kind regards

Graham Tricker

From: "Noble, Jonathan, Mr" <>
Organization: University of the Witwatersrand
Date sent: Tue, 9 Feb 1999 17:58:06 GMT + 2:00
Subject: Greetings from interstage-triode fan, J. Noble, South Africa.
Dear Brian Sowter
Greetings from sunny South Africa.
See how nice your sowter interstage transformer looks on my pp6A3 amp, "Brave Ulysees", at:, see under the diy section, there are photos and a schematic of my amp. (OPT is from a trashed classic Leak point one) 42 kg to give only 8 stereo watts!!

Your IT is doing a great job! With Brave Ulysees and the Ariel loudspeakers (92 db sensitivity) I get a huge 3D sound. On some recordings I get a height illusion, with sounds that seem to eminate from above the ceiling.

P.S. My friend wants me to build him a pp300B, so I will send that order through to you, hopefully some time this year.

Best Regards
Jonathan Noble
Africa's Biggest Triode Fan

From: "Bruno Dal" <>
To: <>
Subject: 845 Amplifier

Date sent: Thu, 8 Apr 1999 22:45:44 +0200

Hello Brian,

Your trannies and chokes work excellent! The big 30H choke works very
well. And the sound from this single ended 845 DIY amplifier is really

Many thanks for your help in my successful project!

Best Regards

Bruno Dal

From: "MAFRAND" <>
To: <>
Subject: 8230 transformer
Date sent: Mon, 24 May 1999 19:01:58 +0200

Hi Brian,
I recently bought a 8230 transformer from your factory.
I am using it as a line input transformer in my power amp instead of a 100
k pot, that is i modified my amp the way i did with my preamp i.e a 8920
transformer instead of a passive stereo-mono converter.
Just great ! The tranny feeds the grid of a 5687 triode direct coupled to
the grid of a 10 DHT itself anode loaded with a 45% permalloy core Tango SE
OPT. The sound is very natural, very transparent, 3-D soundstage, a kind of
a mix of both best aspects of tube and transistor features. Superb. Note I
did my evaluations with a budget CD player, I can guess what it could be
with a high end source...
Bravo for this level of quality ! Keep this good work going on !
Next try will be your 30% permalloy core OPT ...
Best regards,
Dominique Mafrand

From: Цветан ценков []
Sent: 07 December 2011 12:25 PM
Subject: sowter3232

Hi Dear Brian
We are young team ,who design digital sources (dacs).We use output transformer Sowter3232 for output stage differential mode.We use passive I/V convertion ,and  Sowter3232 is most appropriate.
Incredible middle bass and very clean  high frequency.
Congratulations and compliment for your product!!!!

P.S We attached photos on our dac inside Best regards R&T High-end audio design sistem team Bulgaria

Ratsov Tsenkov 24 192 DAC