Closeness of O/P valve, mains and O/P transformer

Greg · Post by **Greg** » Wed Jul 03, 2013 9:26 pm

I have acquired a pair of replacement O/P transformers for my WAD 2A3 PSE amp. They are considerably larger compared to the originals, but offer a considerable improvement to sound when trialed connected with flying leads. For aesthetics, I'd like to 'through mount' them into the chassis. Because of their bigger size, the lams of the O/P transformers will be within 10mm of the glass envelopes of the second output valves and 20mm from the edge of the mains transformer.

Is this OK or will the close proximity of these items have any detrimental effect on sound or performance?

Thanks in anticipation.

Greg

JamesD · Post by **JamesD** » Wed Jul 03, 2013 9:42 pm

Hi Greg,

The closeness to the valve isn't critical - it does mean the OPT will run hotter than otherwise but this shouldn't affect the performance of the OPT - it might make touching the OPT a bad idea though.

The closeness to the mains trannie might lead to hum pickup at 50Hz or 100Hz but is more likely to lead to some extra pickup of hash type noise - I wouldn't expect this to be significant but it might well be noticeable... it might be a different story if the amp used feedback as this sort of noise pickup on the OPTs would then be fed back to the input but on the 2A3PSE this isn't a factor.

Its an amplifier that is well worth some fettling, especially the Sovteks with better OPTs - nice move

James

Greg · Post by **Greg** » Wed Jul 03, 2013 9:53 pm

Thanks James. Your post is very encouraging. I'll go for it! ,

IslandPink · Post by **IslandPink** » Wed Jul 03, 2013 10:12 pm

Sounds interesting Greg - any info to be 'released' on the new transformers ?

Greg · Post by **Greg** » Thu Jul 04, 2013 1:36 pm

Hi Mark,

I borrowed a pair of 3.5K Sowters from Steve S and these made a bit of an improvement, but I remember several years ago, Tony Moore trialed his 2A3PSE with a pair of WAD 2.5K 300B PSE transformers he borrowed from Max and they sounded really good. I now have a pair of these which I've been running in with flying leads and the improvement to sound is significant. They are keepers

Paul Barker · Post by **Paul Barker** » Thu Jul 04, 2013 6:46 pm

the Leak Stereo 20 has three transformers that close or closer. The power transformer in the centre oriented so the magnetic field is going to the front and the back of the unit, so only strays go to the sides where the output transformers are. The magnetic field from the output transformers will miss each other but both will modulate the power transformer. this doesn't seem to break through. So it seems orientation of the power transformer is key.

Torroids are 360 degree magnetic field whereas EI are mainly on one plain. so torroids have to be watched.

We breadboard builders tend to keep out power transformers farther away from out output transformers, mainly so we don't have to reasearch and develop this issue. Leak will have spent hours designing their small amp to make sure it sounded great, but fit the size criteria. So you should be OK too.

IslandPink · Post by **IslandPink** » Thu Jul 04, 2013 8:40 pm

Greg wrote:.. a pair of WAD 2.5K 300B PSE transformers he borrowed from Max and they sounded really good. I now have a pair of these which I've been running in with flying leads and the improvement to sound is significant. They are keepers

Nice one !
I guess you'll get a slightly higher load and more inductance - does the bass tone/timing seem better, for instance ?

Greg · Post by **Greg** » Thu Jul 04, 2013 10:19 pm

Hi Mark,

I very much appreciate your interest in my latest project. Thank you.

What I have now is a sound with considerably more authority, fast (especially for SE) and a much sweeter treble. Loads of speed and attack on notes and micro detail I've not heard before. Bass is great with more extension but much better control. This really is a win win!

Actually, I'm rather gobsmacked. I think I've become an SE convert just as others here are moving towards PP

Anyone in the market for a fully tweaked WAD 300B PP Clone?

Greg

Paul Barker · Post by **Paul Barker** » Thu Jul 04, 2013 10:31 pm

Greg wrote: Actually, I'm rather gobsmacked. I think I've become an SE convert just as others here are moving towards PP

Greg

I am not a convert my pp amp is a shaddow of my SE amp, but it is better than I had hoped, and I am prepared to give it more of a chance with better power supplies.

Cressy Snr · Post by **Cressy Snr** » Fri Jul 05, 2013 7:07 am

I can live with either topology but at the moment my KT120 SE ultralinear amplifier is just edging the EL84s out.

The KT120 is just so easy to get on with, that apart from the loss of one British meshplate, I just switch on and listen. You can't ask for more then that.

Greg · Post by **Greg** » Wed Jul 31, 2013 8:04 pm

Hmmm (or maybe I should say hummm), having successfully trialed these O/P Tx's fly leaded and off chassis, today I removed the original transformers and substituted the new ones on the top of the chassis surface. They are still fly leaded, but now 40mm from the mains Tx. This now hums to a point where it is audible in the listening position. It is the mains Tx that is humming. There is no increase in noise from the speakers. The O/P Tx's sit on both sides of the mains Tx and I have orientated the corresponding Tx coils to be at 90 degrees to each other. Experimenting further I have found moving the O/P Tx's off chassis again, the hum reduces significantly. Re-introducing them to the chassis top one at a time brings hum from the mains Tx with one added and the hum increases with the addition of the second.

I'm inclined to think that unless any of you knowledgable people have any solutions, if I want to continue with these transformers, I may be looking at a rebuild onto a new chassis with a different component orientation. I could even consider monoblocking.

What do you think?

Greg

Andrew · Post by **Andrew** » Wed Jul 31, 2013 9:33 pm

I suspect distance will be your friend on this one Greg, have you tried them in all orientations?

Andrew

Greg · Post by **Greg** » Wed Jul 31, 2013 9:44 pm

Hi Andrew,

Thank you. If I understand what you mean by all orientations, maintaining the 90 degree variance on coil orientation between the mains and O/P Tx's, I have tried them in both the vertical and lateral positions. I hope that makes sense. There is no difference to the hum from the mains Tx either way.

Greg

pre65 · Post by **pre65** » Wed Jul 31, 2013 9:48 pm

Greg, as a temporary measure you could find a nice piece of wood and mount the two transformers on it, similar to what I do.Short as possible connecting wires.

I'm sure someone with your skills could make it look domestically acceptable.

Greg · Post by **Greg** » Wed Jul 31, 2013 9:57 pm

Thanks, Philip, I completely understand where you are coming from in your suggestion. My trouble is, this amp sits on the top shelf of the Hi-Fi rack in my living room. I've considered your suggestion but I simply do not have the room to accommodate it. The listening/living room is much patronised by my dear Amanda who enjoys her television and likes an aesthetic surrounding. She has no love for my Hi-Fi, and given the choice, she would banish all my kit to the local authority dump

In consequence, I have very limited space and a quality 'bodge' as you suggest is probably not viable......I wish

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Closeness of O/P valve, mains and O/P transformer

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