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Old 27th May 2008, 03:16 PM   #1
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Default Cloning a HF-60

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
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Old 27th May 2008, 04:59 PM   #2
kevinkr is offline kevinkr  United States
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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.
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Old 28th May 2008, 05:11 PM   #3
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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
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Old 28th May 2008, 06:39 PM   #4
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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.
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Old 29th May 2008, 12:00 AM   #5
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Quote:
Originally posted by 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.
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
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Old 29th May 2008, 11:26 PM   #6
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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.
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Old 30th May 2008, 12:07 AM   #7
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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
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Old 30th May 2008, 01:21 AM   #8
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[QUOTE]Originally posted by Cycline3

:::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
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Old 30th May 2008, 08:43 PM   #9
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Talking 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
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Old 30th May 2008, 08:59 PM   #10
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Default Re: holy toledo!

Quote:
Originally posted by petera77


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
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