Cloning a HF-60

[petera77]

I'm going to clone a Eico HF-60 to meet my needs.

I gave up on the idea of cloning a VT100 - too complex.

Any suggestions on power and output transformers? I'm looking for specific suggestions.

TIA

 

[kevinkr]

I preferred the sound of the HF-50 frankly, although the HF-60 was also very good.

Someone ought to be able to clone the old T0-330 for the HF-60. Usual suspects: Magnequest, Heyboer, or Electra-Print. Good used TO-330 are rather expensive and not too common on eBay these days.

Hammond 300 series power transformer ought to be fine, as should one of their better chokes.

 

[MQracing]

Hi Kevin:

Building a TO-330 today would be a bit more challenging. The original was built on a non-scrapless punched lamination called an EI-8. It has longer legs (window length) than a normal EI-112. And last time I looked for this shape it was no longer being made.

Of course you could substitute a single or double c-core of the same functional dimensions as the original core had--- but, again, at a price and (from a practical point of view) a minimum purchase buy that will be much larger than for a few pairs of tranneys.

MSL

 

[petera77]

please forgive my ignorance....

what should the plate to plate resistance of the OPT be?

is the Hammond 378X a good fit for the power transformer?

thanks again.

 

[Bandersnatch]

please forgive my ignorance....

what should the plate to plate resistance of the OPT be?

is the Hammond 378X a good fit for the power transformer?

thanks again.

hey-Hey!!!,
It is easy enough to measure the intact output TX to determine its a-a load. It assumes that its secondary was indeed tapped for the usual 4, 8 and 16 R loads. With this, and the voltage ratio squared you can determine the primary load.

You'll need a TO-330 anyway to unwind and determine how it was made. Heyboer is quite skilled at this. I have heard that Jack at Electraprint is as well. If I can be of service, perhaps by providing the engineering sample please let me know.

A search with Google should turn up the dimensions of EI-8, but take one apart first to determine if it indeed uses that lamination. It may also be that a lamination with a shorter magnetic path length could be implemented with slight( and likely useful )modification. Either way, it will be a good thing to have the construction of the old and highly regarded OPT's documented and kept available for reconstructions...

I'd prefer to clone the HF-50's 32007 Chicago iron which Kevin mentioned.
cheers,
Douglas

 

[Cycline3]

I guess I am odd man out today -- feels that way. Anyway, reality check. The old transformers are not all as good as everyone says they are, and new transformers aren't as bad as everyone says they are. In reality, almost NO ONE, and I mean almost NO ONE, on this board should be having custom transformers made to their specs. There is a wide array of ready to go and well engineered iron out there to choose from. Edcor, Hammond, lundhal on the low end, James electra print and others on the more pricey end. Having a custom unit made is likely to cost more than any of them and potentially (likely?) not perform as well. I've been building amps for 20 years and I would not want to tell someone how to wind an output transformer... what next, tell them how to wind our capacitors? Leave that to the people that do that 40 hours a week... not to mention there are very few people who would/could hear the difference between the transformers. It's much less than would say they can. Simply put, unless you just have money to burn, buy a nice set of new transformers already built and focus on your amp's design.

 

[Bandersnatch]

hey Cycline3, I am close to your POV. I have to say that the unwind/reproduction process isn't all that expensive. The first time I had it done was on a Peerless S265Q output. it did indeed work well for me, and as it turned out, was quite easy to modify for use in my unique E-Linear circuits. Cost when wound on a NC winder and mechanical stacker was around $100 each...

In the amp build that the TO-330 was brought in for, it turned out that the modestly priced Hammond 1650R left it for dead...a far better output, even when run conservatively with efficient speakers. Now getting a 1650R with multiple sets of U-L taps across the primary would be neat. I can't help wondering how complex its coil is. I can say with certaintly that the big S271S has a complex set of interleaves/interconnects.

On the vintage, it is important to know its real intended buyer. Some real carp was overpriced then, just as today...and just as now, some builders went to the trouble of acquiring really good output Iron. Separating truth from marketing hype may indeed prove difficult...
cheers,
Douglas

 

[MQracing]

:::The old transformers are not all as good as everyone says they are, and new transformers aren't as bad as everyone says they are.:::

Hi Cycline3.

I'd like to try to constructively add some comments, observations, and perhaps some insights gained from building various audio transformers for 19 or more years now.

Your statement quoted above is too much of a generalization. There were in fact some excellent transformers that were designed forty, fifty and even sixty years ago. And those "vintage" designs have withstood the test of time well, overall.

A good transformer design is immune from the ravages of time. As long as physics hasn't changed so much---- a coil that was designed several decades ago to a very high degree of performance will still have that same performance potential today.

And, yes, just like contemporary production of audio transformers, you will find that "vintage" tranneys varied in performance quality all the way from darned, darned good to stinkers.

I just don't think you can make a sweeping statement about a transformer design based on it's age--- whether old or new.


:::In reality, almost NO ONE, and I mean almost NO ONE, on this board should be having custom transformers made to their specs. There is a wide array of ready to go and well engineered iron out there to choose from. Edcor, Hammond, lundhal on the low end, James electra print and others on the more pricey end. Having a custom unit made is likely to cost more than any of them and potentially (likely?) not perform as well.::::


I agree with you in large measure---- very few designs that I have seen require absolute custom engineering---- and some of the "custom" design requirements that are proposed to builders (like myself) of audio transformers would be, in fact, very poor designs if we simply listened to the customer (who does not know tranneys well) and built to their "spec". I have turned down custom work--- often after explaining the shortcomings and pitfalls--- of the proposed custom design. I mention this because it follows or struck for me a chord in your post about amateurs designing transformers and capacitors and etc.

Today DIY'ers actually have a lot of choices in ironware from a relatively wide range of builders both domestically as well as internationally. From tens of dollars per unit to hundreds if not thousands of dollars per unit.

Instead of doing counterfeits, rip-off copies by a midnight winder or etc---- with so many good choices why not do business with the companies who support the audio community? Many of the companies you mention by name have focused on the needs of the DIY community--- and offer good products. Instead we see some people who are simply engaging in counterfeiting other companies products and illicitly appropiating for themselves the hard earned good will of those companies.


End of rant.


:::I've been building amps for 20 years and I would not want to tell someone how to wind an output transformer... what next, tell them how to wind our capacitors? Leave that to the people that do that 40 hours a week... ::::

Amen.


:::not to mention there are very few people who would/could hear the difference between the transformers. It's much less than would say they can. Simply put, unless you just have money to burn, buy a nice set of new transformers already built and focus on your amp's design. ::::

the other possibility is that we engage in reverse "snobbery" (if that is the right word to use).

What I mean is this. Transformers can vary in cost by several hundred percent---- even when the "funtional" (i.e., electrical parameters) appear to be similar.

As just one example---- look at the Tango lineup--- in both the push pull and SE offerings---- they offer products over a wide price range.
Does that mean that the "expensive" products are rip-offs or overpriced?

Consider that cost of laminations can vary from say eighty cents a pound to well over two hundred dollars a pound for some of the exotic laminations.

Insulation materials can be simple mylar, polyproplyene, nomex, teflon, kraft paper, fish paper, and etc. The cost differentials btwn several of these insulating materials can be huge.

Magnet wire--- the type of insulation used on the wire can vary the cost quite a bit---- as well as the material itself (silver vs copper, OFHC vs ETP110, Litz vs solid conductor, etc).

On some designs the "bill of materials" going into design (not even accounting yet for any labor) can far exceed the cost of a finished product where every materials choice within that transformer was done with simply decreasing the "costs of good sold".

So that some of Tango's more expensive transformers might actually have a smaller gross profit margin than some of their less expensive models.

What I think is neat is that folks have a wide range of choices--- all the way from silver wire to amorphous cores to cobalt to teflon insulation---- in this sense perhaps to some extent today (i.e., modern times) we are in the "golden age"?

What do you think?


MSL

 

[petera77]

holy toledo!

I had *no* idea that asking for a recommendation regarding a output transformer for a HF-60 clone would turn into this thread.

Alas, I stil have no recommendation.

I want to be clear: I don't need a clone of the original OPT, just a decent OPT that is electrically equivalent.

No one has mentioned what the plate to plate resistance might be, either.

j/k

 

[MQracing]

Re: holy toledo!

I want to be clear: I don't need a clone of the original OPT, just a decent OPT that is electrically equivalent.

No one has mentioned what the plate to plate resistance might be, either.

j/k

You can read the Acrosound catalog at the following url;

http://www.clarisonus.com/Archives/Trans/Acro55.pdf


Briefly the output transformer has a 3300 ohm CT winding with UL taps. It is rated at 50 watts.

best of,

MSL

 

[Bandersnatch]

hey-Hey!!!,
The Acro is ~4k to the 8R tap and ~5k v. the 4R tap. As far as suitable, something like 5k a-a is how I'd want to go. The 1650R is a big one but a good one. It would depend on what sort of hurry you're in. I'd prefer a design with a more consistent loading between the taps. I'd suggest one of the Peerless designs, but as originally wound they've only got U-L taps at 50%( if at all ), and some of them drop the '8R' tap load( turn ratio-ed for a 9R load ).

Cloning a design constructed to deliver maximum power is not what I'd consider a good idea. Increase the plate-to-plate load to more like 6k, and drop B+ to 400 or perhaps less. The general design is OK. The Mullard circuit is quite capable. Adjust values slightly if you take this route, scaling values to deliver operating points of the same fraction of B+ as originaly specified.

As to the rest, it is indeed a bit old and tiresome to be attacked in that fashion, sorry for the distraction.
cheers,
Douglas

 

[jon_010101]

To Petera -- If on a tight budget, and if it is true that the Hammond performed better than Acrosound as Bandersnatch says, then Edcor might be an even cheaper and better option. I recall a neat comparison done (LINK) where it was found that an Edcor had better high frequency performance than Hammond, at the expense of a bit of LF. The distortion and frequency response measurements they achieved were fantastic for any tube amp. 0.03% THD at 1W, 5-150kHz +/-3dB.

The circuit you are interested in is fairly good for stability, and it should not take to much work to get working (some tweaking of feedback compensation values). Perhaps someone on this forum has done an Edcor Mullard circuit?

 

[Cycline3]

Come on again

Your statement quoted above is too much of a generalization. There were in fact some excellent transformers that were designed forty, fifty and even sixty years ago.

There are a couple of nice replies to my post earlier but I still stand by what I said, even more now. There is no generalization. Old transformers aren't all that. No vintage amp sounds like one I can build with modern components. None. Do not fool yourselves. We are fortunate victims of modern engineering - we can build a power supply for cheap that a designer in 1958 couldn't imagine. Remember some amps only had 8uf of filter capacitors! And that was considered generous! We can get a 1500uf 450V cap for a very reasonable amount of money, something unbelievable then.

The original poster didn't even know the impedance ratio of the output and people are saying, "CUSTOM WIND!"

Get a clue, grow up and be helpful. 90% of the posters are complete nOObs and the ones that should consider custom wound, don't need you to tell them how to do it. So please, do the DIY community a favor and be responsible. Because you aren't now.

There is no "MAGIC" about 1950's tube technology. None. If anything related to the industry hasn't gotten better - it certainly isn't transformers and power supplies. That's the one place that has remain consistent and been developed through to this day.

If you guys you pay attention, you'd ask for better tubes! Not caps, transformers, resistors or wire - all of which have BENEFITED from 50 years of development!

Please help nOObs, not recommend stuff you only wish you'd done as a real solution. There is ZERO excuse for anything else in this case, point this guy to some nice, new iron and let it go.

 

[jon_010101]

Re: Come on again

There are a couple of nice replies to my post earlier but I still stand by what I said, even more now. There is no generalization. Old transformers aren't all that. No vintage amp sounds like one I can build with modern components. None. Do not fool yourselves. We are fortunate victims of modern engineering - we can build a power supply for cheap that a designer in 1958 couldn't imagine. Remember some amps only had 8uf of filter capacitors! And that was considered generous! We can get a 1500uf 450V cap for a very reasonable amount of money, something unbelievable then.

A possible concern is that old amps are designed around a specific output transformer and its characteristics. So, some of the feedback compensation tricks used will need to be recalculated, or empirically redetermined. It is much easier to build an old design around an original transformer if one wants it to be plug-and-play. That said, I think an Edcor would probably work great in a simple Mullard design, as long as the builder was willing to tweak a few parts values to tune the response.

I do agree that it is incorrect to label transformer-making as a black art, or worse, a lost art. But I've also heard horror stories of people trying, and failing, to build a Citation II copy with a Hammond transformer. Higher power / high feedback tube amps really do require a premium output transformer, and there are only a few expensive options today. Personally, I can't afford Lundahl, Sowter, Peerless or Plitron, so I look to vintage amps to rebuild for a fraction of the cost of a new set of iron (or buy something from Edcor). I would argue that many vintage amps probably can and do sound equal to those that might be built now -- But only after they are properly refurbished and upgraded. My restored 1950's amps are all filled with modern upgraded parts, and sound/perform much better for it.

 

[Bandersnatch]

Re: Come on again

There are a couple of nice replies to my post earlier but I still stand by what I said, even more now. There is no generalization. Old transformers aren't all that. No vintage amp sounds like one I can build with modern components. None. Do not fool yourselves. We are fortunate victims of modern engineering - we can build a power supply for cheap that a designer in 1958 couldn't imagine. Remember some amps only had 8uf of filter capacitors! And that was considered generous! We can get a 1500uf 450V cap for a very reasonable amount of money, something unbelievable then.

So then, what is it about the modern output that is so much better than the best of the vintage designs?

Fact is that most of the old ones were cost-point engineered, and were only as good as they had to be. There has been no large shift in consumer demand for quality audio. Most of the stuff was no better than the BestCircuitCity stuff that is available today.

There were some exceptions. Jon's mention of the Citation II comes to mind. The similar( but monoblock) Heathkit W6 for another.

While the capacitor ref is valid, I still prefer the minimalist approach in that area, favouring polypropylene film caps over the lossy 'lytics. Designs running Class A are a lot easier on their PS than the AB ones for another...and none of the commercial stuff is really class A( save for the SE ).
cheers,
Douglas

 

[Cycline3]

Looking to the past is unhealthy. That's not a hobby ... that's like chasing the Holy Grail of Audio or something. Like one even exists.

Again, every facet of the technology has progressed in the last 50 years except the manufacture of the actual tubes. Electrolytic or/vs polypropylene is a silly reference - as it means nothing in real terms - as BOTH are improved vastly over their old world counterparts. Saying you prefer Poly - doesn't mean OLD amps sound better. Which was what started this to begin with.

There's nothing special about those old amps... there were good ones and bad ones. I've had and have both. Yeah there were some GEMS, but living in the past is just bad form, no matter how you look at it. And you can make a NEW GEM if you do it right. You have to focus on what you have at hand.

Also, most of the questions on here come from people with no or little experience. Pointing them to costly, rare old parts on ebay is not helpful in my opinion. I've seen crappy organ amps that had more rust than most old cars sell for stupid amounts of money. Because everyone says the old stuff is better. Not. Again. NOT.

Everyone has a right to choose what they like or buy for themselves, but when you are dealing with a hobby that is both expensive and potentially dangerous/deadly, I feel that what is in the interest of the community at large comes before your own personal bias.

Recommending to people to custom wind transformers that don't even know what an impedance ratio is (another thread)... is NOT helpful. Having someone try to replicate some obscure old transformer is NOT helpful.

Pointing to $25 edcors for a beginner is helpful as someone mentioned. That is good. $600 for a stereo 70 on ebay? Not good.

I've been reading this board for awhile now - and the 2 things that stand out the most about that time is: 1. People will regurgitate any myth they've read on the web like it's gospel and even argue with you about it, even though they lack any basic understanding of what's happening to proove it. and 2. People will point others in crazy directions in search of the Audio Grail, because they dreamed of doing it but never did.

Copying a classic amp is one thing. Telling someone to get custom transformers is another. I hope that the rest of the messages focus on helping this person achieve his goals, not point him in search of some lost Indy artifact.

Buy some good, affordable, modern iron and go from there. You will NOT be unhappy with it.

I am extremely passionate about the tube industry and seeing DIY do well. Im sorry if I upset some in that, but I won't hesitate to say BS if I think what you're saying is harmful. I want people to enter the hobby, enjoy it and be happy. Telling them the only way to what they want is to secure a transformer from some old amp they may NEVER IN THEIR LIFE FIND, is not helping anyone!

Think of it like this, just because you can tear down a car engine and rebuild it, would you start making one of your own from scratch? No? Then why make your own transformer? Most people don't even know basic tube theory - much less how to wind iron. And if you do know, you don't need to ask or have someone suggest it... Have I said it enough yet?

 

[Boris_The_Blade]

Dude you gotta settle down - reminds me of Larry David. There are good old and new designs and bad old and new designs. If peter wants to pay a premium for a known-good but old transformer design - that's his prerogative. He said he wanted to clone it....

 

[Bandersnatch]

Also, most of the questions on here come from people with no or little experience. Pointing them to costly, rare old parts on ebay is not helpful in my opinion. I've seen crappy organ amps that had more rust than most old cars sell for stupid amounts of money. Because everyone says the old stuff is better. Not. Again. NOT.

You've yet to say anything substantive about why only new is good, or for that matter why old isn't. Do us all a favour and spell it out in detail.

Everyone has a right to choose what they like or buy for themselves, but when you are dealing with a hobby that is both expensive and potentially dangerous/deadly, I feel that what is in the interest of the community at large comes before your own personal bias.

Take your own medicine. We'll ALL feel better.

Recommending to people to custom wind transformers that don't even know what an impedance ratio is (another thread)... is NOT helpful. Having someone try to replicate some obscure old transformer is NOT helpful.

First of all, the impedance ratio was answered, once wrong, according to the catalog, and once according to some direct measurement.

Copying a classic amp is one thing. Telling someone to get custom transformers is another. I hope that the rest of the messages focus on helping this person achieve his goals, not point him in search of some lost Indy artifact.

There are no 'lost artifacts' in the land of audio Iron. All it takes is one sample and you can make more, and likely with some cost saves fixed.

Buy some good, affordable, modern iron and go from there. You will NOT be unhappy with it.

Entirely possible, but not any more sure or substantiated than any other of your statements.

I am extremely passionate about the tube industry and seeing DIY do well. Im sorry if I upset some in that, but I won't hesitate to say BS if I think what you're saying is harmful. I want people to enter the hobby, enjoy it and be happy. Telling them the only way to what they want is to secure a transformer from some old amp they may NEVER IN THEIR LIFE FIND, is not helping anyone!

Where was that suggested? I don't think we missed anything. If that is indeed what you heard, I suggest re-reading, perhaps without deciding what it is going to say first.
cheers,
Douglas

 

[jon_010101]

Pointing to $25 edcors for a beginner is helpful as someone mentioned. That is good. $600 for a stereo 70 on ebay? Not good.

With all due respect, $600 for an ST70 on eBay is crazy. You can get a decent one for half that, which is less than what the chassis and transformers would cost new! In just the past 2 years on eBay, I acquired three excellent vintage integrated amps for $100-150, and a hideous Citation II for $500. At their individual pricepoints, not one could be duplicated to a similar level of performance with modern iron. For any of the sub-$200 amps (Sherwood, GE, and Bogen), the iron alone would be equivalent to $150+ through Edcor. The output transformer laminations on the GE, for example, are visibly better/thinner than standard M6 I see in new transformers, too. For the Citation II, new iron is unobtainium. Vintage amps can offer tremendous value, especially for lazy farts like myself who don't like building chassis. Mind you, all of those needed new guts, but the foundation is what counts

 

[Bandersnatch]

For the Citation II, new iron is unobtainium.

Not for long...or at least a few weeks beyond the time I decide to wreck one of the originals in my Citation II. First I plan a direct comparo with the 16431 of the Heathkit W6. It may be that I won't ever take down one of the H-K units and instead do the big Peerless. That one would get some secondary mods, likely terminating them as two 4R coils and eliminating the 70V( an extra 16R worth of turns ) capability. More on that as the project develops...
cheers,
Douglas