Output transformer for EL84 PP

[limono]

Isn't Leak TL12 Kt66 amp? I had TL50 plus monos (completely restored) They sounded mediocre on modern speakers like Living Voice, Audio Note (Snell) and plethora of monitors. The only speakers they sounded quite wonderful was a pair of old Tannoy Red 10" . A rare instance of two mediocre components which had some synergistic magic going on mutually filling up the performance gaps .
Coveted Leben uses small Hammond Opts and everybody is raving about it.
Buy old Audio Note PP-1 EL 84 or even better their even older kit 4 6V6 version . They should be accessible in UK. You have the best transformer houses there why look for a junk worldwide ? There is absolutely ZERO reasons to build a cheap DIY amps if your'e healthy and have a pair of hands capable of holding a shovel and a broom.

 

[6vheater]

TBQH I find this subject fascinating.
The original poster talked about the TL12+, then a whole load of people went off like this:-

The UK had many great output transformer companies as well as complete amplifier producers. Nearly all made an EL84 offering.

I can't really understand why this is so, but then I find there were lots of different variants:-
TL12 Plus (EL84), TL12.1 (KT66)..
The OP is talking about the noval version which was cheaper and less powerful, using UL mode instead of triode strapped KT66- all adding to confusion.

I have a pair of KT66 based monoblocs which I rebuilt, same era as the original Leak 1948-9.
(They were originally 807, so I converted them to the KT8, which is a B5 based KT66 with TC.
They are directly coupled AB2, some trick you can't do with EL84.)

TBH when I compared one converted channel to an original unconverted channel I couldn't tell any difference at all, after a vast number of improvements were made in the PSU and upstream in the AF & driver area.

DTN W, held the KT66 triode strapped, sounded exactly like a PX4, DHT, so the critique of the so called "magic sounding"KT66 perhaps "ain't neccessarily so!"or more PSU sag was more fun?

What were the BBC thinking?
They bought loads.

Original GEC ones have are no longer available, and fetch very high prices, as it is one of the best audio power valves ever made.

...ahum.

Therefore the stratospheric prices for MOV KT66 compared with the dirt cheap 807, or EL84 clones, are just another one of those myths or legends, or can people not tell the difference between a mediocre sounding UL EL84 and a mediocre sounding KT66?

 

[disco]

The leaves are falling and all trolls come out...

 

[limono]

The leaves are falling and all trolls come out...

Of course , the leaves are falling and "experts' who listen to Disco are the most qualified
Leak transformers were nothing special, Stero 20 was a so so amp as well and truth to be told ole Dyna ST35 isn't that great either in absolute terms.
BBC was buying shite loads of anything they could extort for next to nothing and was rugged and passable quality. The speakers were lovely though, cheaply built as they were..
If the OP is going to buy run of the mill trans why not to buy an entire Chinese el 84 amp (copy of Andy Grove designed Audio NOte kits EL84 amp on E-pay) or modify it for whatever circuit he wishes to have it ? Since he won't be able to properly implement feedback for a given OPts and circuit does it really matter what he buys?

 

[6A3sUMMER]

6vheater,

OK.
Thanks for the ideas.

And yes, I am a proponent of properly designed parallel tubes (Both parallel push pull, and parallel SE).

Please continue:

What are a few types of true Pentodes that you most recommend?
(not Beam Power tubes)

Can you post a schematic or two of your amplifiers, please?

Can you give us a link, or a complete name, so I can read some writings of Jack E.
or J. E.?
(same person?)

I have designed and built a push pull amp around 7591 tubes.
I have considered using them in parallel push pull too.

What about EL34 and KT77?
It seems the specs are similar, but the suppressor grid versus the beam formers are quite different structurally, and e-field wise too.

What was the EL34 output circuit configuration where you saw the grids glowing (screen grids?).
Pentode mode, Ultra Linear, or Triode wired?
Push Pull?
Single Ended?

Which came first, the 6BQ5 Beam Power tube, or the EL84 Pentode?

Thanks for your time!

 

[6A3sUMMER]

6vheater,

All this discussion of history has reminded me of my Dad's 1947 Magnavox.
It had Parallel Push Pull with 4 6V6 Beam Power tubes, powered by dual 5Y3 rectifiers.

 

[limono]

Parallel EL84 supposedly mimic Siemens F2A post tube "magic". Funny but I'm switching tonight between AN OTO SE (with Lundahl PSU choke input and SS /tube rectifier) parallel SE EL 84 and humongous Audio Matiere Equilibre with Parallel PP 6550/EL34 pairs

 

[6vheater]

BBC was buying shite loads of anything they could extort for next to nothing and was rugged and passable quality.
The speakers were lovely though, cheaply built as they were..

I have no idea why you are slagging off the BBC.
They were doing nothing of the sort.

The BBC is still today one of the leading broadcasters in the world, sponsoring and running the largest music festival of music in the world.

The fact is, they made huge research for decades into improving sound quality in every sphere of broadcast & audio, had one of the leading laboratories in the world as well as set international standards for FM stereo, which nobody in the USA has managed to equal.
No equivalent exists even in Germany, who tried to foist competing standards on the EEC.

Their speakers were NOT cheaply built at all, in fact several companies went under making them, because they were so difficult to reproduce accurately, so that they always matched the BBC's exacting standards.

The BBC were the organisation that introduced PCM audio links to Europe AND were the first to standardize stereo FM broadcast.
A whole hifi electronics industry during the 40s-70s was grown up on the back of this, which there is no doubt was world leading.

The British electronics industry aided by the BBC, with legendary names such as Mullard, GEC, Brimar, Partridge, Parmeko, Vortexion, Gardner, Plessey to name just a few, pushed along by huge military defence contracts were a remarkable success story, which beat the French hands down in quality.

I mean, when you are a small country single handedly making nuclear weapons,testing them, designing computers, building V bombers, the first nuclear power stations in the world and your own guided missiles, that makes a pretty big valve based industry, before the transistor and I.C. came along.

The Americans even now copy DTN Williamson's amplifier by the million, Blumlein's now everyday inventions and Gerzon's surround sound ideas.
(Blumlein invented the Magnetron).

What bit about the British BBC do you hate so much as to come out with such uninformed nonsense?
Fact is, the BBC forced manufacturers to improve their products, I even bought gas voltage stabilisers which were ex BBC stock. (date 1953).

Finally to answer some other point:-

6vheater,
Can you give us a link, or a complete name, so I can read some writings of Jack E.
or J. E.?
(same person?)

J.E =
Elliano boss of ELECTRAPRINT.

Well known transformer maker.
No doubt at all, some of the very best in the world.
His SE stuff is legendary
(just not my cup of tea).

 

[baudouin0]

Digikey do hammond tranformers

 

[disco]

The British electronics industry aided by the BBC, with legendary names such as Mullard, GEC, Brimar, Partridge, Parmeko, Vortexion, Gardner, Plessey to name just a few, pushed along by huge military defence contracts were a remarkable success story, which beat the French hands down in quality.

You're really full of it, aren't you? If it was not for this particular valve you'd all be speaking German. Forget that "of Eindhoven" as Philips had dozens of plants all over the world.

 

[kodabmx]

If it wasn't for Stalin, we'd all be speaking German but that's another story...

 

[6vheater]

I just realised you are a Dutch Disco, and the person who attacked the BBC was American.
I'm really not into ad hominem attacks nor OT diversions.

I'm not at all sure why the British should all be speaking German, but I can certainly feel a wind of change right now for a proud people.

They are quite a diverse ethnic bunch, you know.
Some of us speak the oldest languages on that island.
Some of the best bands, best studios and best audio comes from London, and it doesn't date from yesterday.

The BBC used a lot more stuff than just LEAK, they were into Quad, KEF, and lots of other highly innovative stuff.
Their current musical digital offering on the internet is probably the highest quality live audio streams in the world right now, especially the PROMS.

Eg. Did Holland ever have a Michael Gerzon or a Prom season?

 

[disco]

True, Russian people made the biggest sacrifice in WW2 what is often forgotten these days. What is also factual, is that British radars in 1940 run from Dutch All-Glass valves (scroll down half way to skip the history of Philips). I'm not sure about Gerzon or Prom but we held the first radio broadcast in history, in 1919 Furthermore I don't hesitate to admit I'm a big Anglophile wrt both music and hifi, but it's a pitty equipment wasn't built to German standards, haha.

 

[limono]

where did you get an idea I was BASHING BBC? I only stated they were cheaply built and they are material wise cheaply built like most all British based Hi-Fi. To get something British which is built to any standard costs arm and leg. Sound has nothing to do with it as it is often lovely.The nature of big organizations is that they get something which is reliable and works good enough. And give me a break with a small island. It was an Empire sucking world resources for hundreds of years not to take anything from the Island's people technical and civilisational genius. I play Audio Note Amp through DNM wires on BBC SP1/2e speakers as I type...
The only country who won the war is USA and now it seems the war was great for Germany since it's achieving peacefully what it couldn't do with force . All the other countries lost and especially Russia and Britain, which lost BIG time.
Back to the topic, to have a Leak sound one has to buy a Leak and change ALL the leaking capacitors. leak are still cheap compared to new quality amps. But if cheap is still too expensive, Chinese amps offer a good platform and sound decent enough. I don't picture the OP building a feedback amp worth it's salt with unknown transformers unless it's just for fun

 

[6vheater]

where did you get an idea I was BASHING BBC? I only stated they were cheaply built and they are material wise cheaply built like most all British based Hi-Fi.

To get something British which is built to any standard costs arm and leg.

,,, Chinese amps offer a good platform and sound decent enough. I don't picture the OP building a feedback amp worth it's salt with unknown transformers unless it's just for fun

I don't know how you manage to make more wrong statements in one hit.
The Leak amplifier was hideously expensive at the time of launch, which let's face it was 60yrs ago.
Most people could not get even close to affording one.
I can't think of a US amp that could match 0.1% distortion in 1948 especially with the 6L6.
The British made a whole generation of extremely competent hifi systems as soon as stereo became established, even the 1967 Sugden (world’s first solid state pure class A amplifier, the A21) still sounds superb.

The LEAK TL may not be brilliant today, but how much stuff you see made 50-60yrs ago is still working like the day it was made, or hasn't been thrown in a skip, like they did with most yankee valve amps once the transistor arrived.

Next:-
British hifi cheaply built, you gotta be kidding!
The Quad ESL was totally unaffordable to most people.
Nothing from either Germany or France came (or even now) comes close.

In the late 60s early 70s,-
Along came British Rock, and the KT88 became king.
Even Reeves amazing Hiwatt guitar amps are HIFI amps with staggeringly good transformers.

I have a pair here, they are better than UTC LS series, and can churn out 200W, with very low distortion.
Do you know they measure flat from 8hz to 50khz?
They weren't even especially expensive.

I wouldn't mind betting you could drop a 1970s DR400 into a hifi system direct tomorrow, it would sound better than 99% of what is being sold today, and probably melt the speakers too.

You heard of Partridge?
The British bands got their own "sound" as a result of what they did with those amazing valves and transformers.
I have no doubt a Sowter made transformer is right up there among the very best of the best especially for the EL84, and they are among half a dozen of similar quality.

The BBC also have their own sound.
It takes years to form engineers to do stuff so consistently.
It became a tradition of excellence like Calrec or Rupert Neve's incredible creations... you know the stuff the BBC use daily

I'm not at all sure you know what you are talking about with all the incredible generalisations.

The Williamson amplifier was considered to be so world leading by generations of international designers that a large percentage of US makers copied it and then claimed their "ultralinear" to combine with it was a US idea.

Chinese?
Oh dear, nothing more to say there.
The day I see something from PRC that lasts 2 years we can applaud.

Anyway back on topic?
EL84 transformers?

You can't do better than fit a pair from the golden age, or transcendar who make almost exact replicas of them.

 

[Francois G]

Anyway back on topic?
EL84 transformers?

You can't do better than fit a pair from the golden age, or transcendar who make almost exact replicas of them.

Interesting “discussion”, but glad we’re back to the OP topic. I’m interested in hearing from people who had used these Transcendar transformers. How much did they cost? What did you find? Perhaps mistakenly, I had assumed that they were OK, but not great.

Also, how do you buy Transcendar trannies? I’ve been on their website, but there is no online shopping. Looks like you have to email them with a request for a price quote for a specific transformer. Can this be right?

 

[Francois G]

In another thread (see post #16) I had just posted about my positive purchasing experience of Toroidy EL84 output transformers. I have not used them yet, so I can’t testify to their fidelity and performance, but the buying experience was very positive. General feedback from the Baby Huey threads is very positive about the Toroidy output trannies.

Baby Huey GB PCB - EL34 Build Thread

I plan to build 2 Baby Huey stereo (BH) EL84 amplifiers, first to use a pair of these Toroidy outputs, second with a pair of Acrosound 310 output transformers (the best vintage EL84/8400 Ohm OT’s I know of). Interesting showdown. Problem is that my hearing is not that good. So, I will need people with accute hearing to help me.

 

[Francois G]

In another thread I had just posted about my positive purchasing experience of Toroidy EL84 output transformers. I have not used them yet, so I can’t testify to their fidelity, but the buying experience was very possitive.

Baby Huey GB PCB - EL34 Build Thread

 

[6vheater]

Scott and Bogen EL84/7591 6V6 transformers are widely regarded as being the best, or some of the best most fantastic sounding made. (I never tested EICO, but Gillespie is the guy for them).
Bogen used Selectron cores.
They were true hifi amps.

I tested initially both, with the usual mix of dubiousness and disbelief.

Also I happened to cross paths with the guy who ordered the same Transcendar OPTs I tested in an amp (except I used originals).

He told me, it was him sent the originals in to TSCDR to be reverse engineered, so that completely faithful replicas of the originals could be made.
What he told me, they came out apparently absolutely identical in all respects to the originals, so in effect Transcendar are doing something similar to Sowter, but in the USA.
(don't knock it until you tried it!)

There's an Italian guy doing faithful copies of the DR100/200/400 partridge transformers which are a real handful to do.
If you look around, for nearly any specialised amp out there, there's a specialist who has gone to the trouble of replicating stuff accurately and even improving on them.

There is a real expert or 2 in the USA who knows a lot about lams, mag saturation characteristics, and how to make stuff like in the old times.

There's a lot to be discussed about the differences between E-I cores as having a clear advantage over toroids in power transformers, (partly to do with electronic noise/DC offset filtering and all sorts) so I wouldn't be suprised if this were the case in OPT toroids.

You won't see a toroid anywhere near J.E, and certain high performance OPT makers,even Edcor, so there must be a good reason for it, whereas as Poland is Poland, and such people like to "reinvent the wheel".
I suspect once you introduce high winding ratios between Prim-Sec, this is where the trouble starts.
eg. I never saw a toroid in a high power guitar amp, despite all the obvious advantages.

I use toroids for supplying heaters, and that's it, but I am tempted to try some for HT with just 1:1 ratio and voltage doublers from 220>635V DC a la Bogen MO series.

Triad make such a thing in the VPT230-110/2170/430/1090 world series,so that gives you plain vanilla 325V or 325V & 650V.

Now back to the Bogen amp.
I was astonished to read the original literature with the claims, & see a banal 6V6 amp (with some rather unusual circuit features) give superb low distortion, and a frequency response essentially flat from 30hz to 25khz.
I don't recall anyone ever having tested one of these. It didn't deliver the claimed output power, it was about 3-4W short, but who cares.
The core is pretty small, which may explain some obvious saturation around the LF.
Everyone says they sound superb, weigh not a lot, use hardly any power and are pretty cheap if you can find one.
I am looking to get transcendar to reverse engineer & rewind this OPT, because it's perfect for 6V6 and so the EL84, + I have a pile of spare old cores sitting here which I can make CT drive chokes with and all sorts.
(Bogen made cores in 3 basic sizes, small, medium and large, and they are ALL drop thru which I like a lot).

The Scott I tried was quite similar in a lot of ways to the Bogen, but much heavier & very compact.
Scott made most of the 222 series with EL84 in, so they're basically an outsize core for a 25-30W amp.
The 7591version was a lot bigger, which is what I tested.

Having wired up one of these Scott OPT with a modern pentode PPP arrangement I have to say the performance was nothing short of astonishing.
In fact it was pretty outrageous.

The original amp was designed with 40-43W in mind,but because of limitations in the PSU they could never manage that with both channels driven...basically lucky to get a clean 25W, very much apparently like many EICO I am told.

With my PPP Opvs - perfectly matched output valves, I was getting 48W per channel perfectly clean, with distortion approaching 0.1-0.2% + IMD vanishingly low.
Approaching clipping it was more like 53W.

There was practically no difference in waveform whether it was doing 500mW or 45W.
That is something like 3-4x what a pair of EL84 will manage.

Frequency response was much like the Bogen, with some slight LF saturation if you really abused it, but of course that's quite a punch of 96W clean from 2 channels compared with just 18 of the 6V6....or a rather lacklustre 45-50 distorted watts from the original 7591 versions.

That's what I tried.
I have the waveforms and stuff logged, so sure as anything I would be willing to test anything.
Had enough of my say now, nothing more to add, and have a plane to catch.

 

[limono]

I don't know how you manage to make more wrong statements in one hit.
The Leak amplifier was hideously expensive at the time of launch, which let's face it was 60yrs ago.
Most people could not get even close to affording one.
I can't think of a US amp that could match 0.1% distortion in 1948 especially with the 6L6.
The British made a whole generation of extremely competent hifi systems as soon as stereo became established, even the 1967 Sugden (world’s first solid state pure class A amplifier, the A21) still sounds superb.

The LEAK TL may not be brilliant today, but how much stuff you see made 50-60yrs ago is still working like the day it was made, or hasn't been thrown in a skip, like they did with most yankee valve amps once the transistor arrived.

Next:-
British hifi cheaply built, you gotta be kidding!
The Quad ESL was totally unaffordable to most people.
Nothing from either Germany or France came (or even now) comes close.

In the late 60s early 70s,-
Along came British Rock, and the KT88 became king.
Even Reeves amazing Hiwatt guitar amps are HIFI amps with staggeringly good transformers.

I have a pair here, they are better than UTC LS series, and can churn out 200W, with very low distortion.
Do you know they measure flat from 8hz to 50khz?
They weren't even especially expensive.

I wouldn't mind betting you could drop a 1970s DR400 into a hifi system direct tomorrow, it would sound better than 99% of what is being sold today, and probably melt the speakers too.

You heard of Partridge?
The British bands got their own "sound" as a result of what they did with those amazing valves and transformers.
I have no doubt a Sowter made transformer is right up there among the very best of the best especially for the EL84, and they are among half a dozen of similar quality.

The BBC also have their own sound.
It takes years to form engineers to do stuff so consistently.
It became a tradition of excellence like Calrec or Rupert Neve's incredible creations... you know the stuff the BBC use daily

I'm not at all sure you know what you are talking about with all the incredible generalisations.

The Williamson amplifier was considered to be so world leading by generations of international designers that a large percentage of US makers copied it and then claimed their "ultralinear" to combine with it was a US idea.

Chinese?
Oh dear, nothing more to say there.
The day I see something from PRC that lasts 2 years we can applaud.

Anyway back on topic?
EL84 transformers?

You can't do better than fit a pair from the golden age, or transcendar who make almost exact replicas of them.

Do you comprehend the difference between cheaply made and cheap (and quirky) ? I am aware that British stuff was and is very expensive for what it is materially but it sounds good enough. It is fortunate that the audio development was taxpayer paid but the taxpayer had to pay a lot to enjoy the fruit of the development.