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My Singlepower Supra Experience - Why mine almost blew up like a Hand Grenade (and yours might too) - Page 12

post #166 of 314
8/1/09 at 11:24pm
Quote:
Originally Posted by HeadphoneAddict View Post
What happens if you put an egg on the trafo? Does it get cooked?
Hi Larry

It's 3:22am right now.
I'll try this tomorrow morning.
If I succeed I'll perhaps throw some Danish bacon on there
and at least enjoy a full breakfast while I consider the consequences
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post #167 of 314
8/1/09 at 11:32pm
Quote:
Originally Posted by thathertz View Post
Hi Larry

It's 3:22am right now.
I'll try this tomorrow morning.
If I succeed I'll perhaps throw some Danish bacon on there
and at least enjoy a full breakfast while I consider the consequences
BACON!
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post #168 of 314
8/1/09 at 11:34pm
Quote:
Originally Posted by HeadphoneAddict View Post
BACON!
Oh yeah. DANISH Bacon

I can almost smell it now...

(Or is that my transformer?)
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post #169 of 314
8/2/09 at 12:17am
I have to say this - I don't have a single tube amp whose transformer does not get hot during use...
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post #170 of 314
8/2/09 at 6:28am
It sure sounds like your amp has a Hammond filament transformer acting as a high voltage unit. If we look past how utterly stupid this is, the transformer is running way out of spec and is slowly burning up. A transformer run on the limit is warm but never hot.
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post #171 of 314
8/2/09 at 8:19am
Don't know if you can identify the transformer by this but here's
my MPX3:

http://www.head-fi.org/forums/f42/sold-431635/
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post #172 of 314
8/2/09 at 8:26am


From : Angela Instruments Online Catalog - Transformers

Looks like you're right Spritzer.

So what's the next step?
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post #173 of 314
8/2/09 at 8:30am
Quote:
Originally Posted by spritzer View Post
It sure sounds like your amp has a Hammond filament transformer acting as a high voltage unit. If we look past how utterly stupid this is, the transformer is running way out of spec and is slowly burning up. A transformer run on the limit is warm but never hot.
Spritzer, could you please explain why this is so stupid and what
could be done to improve / fix the situation?
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post #174 of 314
8/2/09 at 9:08am
Looks like your amp doesn't have a filament only transformer but one of the 270 range from Hammond. They are a plate+filament combo transformers but 115v only. With the sticker removed it will be hard to identify it unless you take note of the wires it has, it's exact dimensions and how much it weighs and compare that to the Hammond spec sheet. These transformers are available in a range of sizes so you could very well be driving it past its limits now. There is a 370 range though which can be configured for 230v operation so your best bet would be to upgrade to one of those that can handle the current needed.

As for running the second primary as a secondary, it was never designed to run this way and it cuts the power current capability of the transformer in half. You are cooking the single primary to say the least...
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post #175 of 314
8/2/09 at 9:37am
Quote:
Originally Posted by thathertz View Post
http://angela.com/images/categories/272BXOne.jpg

From : Angela Instruments Online Catalog - Transformers

Looks like you're right Spritzer.

So what's the next step?
The transformer on your amp, while a Hammond, is not at all the same as the small filament trafo that we're talking about in the Extreme thread. I should make something very clear here, the problem in the Extreme is not that Hammond was the man'f of the trafo, only that a transformer that they man'f was improperly used. I've built a number of things using their products and when used properly they perform just fine.
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post #176 of 314
8/2/09 at 10:00am
Quote:
Originally Posted by n_maher View Post
The transformer on your amp, while a Hammond, is not at all the same as the small filament trafo that we're talking about in the Extreme thread. I should make something very clear here, the problem in the Extreme is not that Hammond was the man'f of the trafo, only that a transformer that they man'f was improperly used. I've built a number of things using their products and when used properly they perform just fine.
Sure Nate, I'm sure the trafos are good quallity.

Even though it's a different trafo than the one in the Extreme, the still
issue still applies though: the transformer is being driven beyond it's
capabilities?

Nate, could you or perhaps Spritzer recommend a suitable current rating
for the Hammond 370 trafo?

Thanks for your help.
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post #177 of 314
8/2/09 at 10:06am
See the thing about the hammond 300 series transformers is that they
are designed to run a tube rectifier. A significant amount of current goes
into the 5 volt winding, or multiple 5 volt windings. The transformer is a stock
unit, not really rated for what it is being used for. Unfortunately, i have not
been able to find a stock transformer that is perfect for use with extremes.
You have to buy a custom unit, And if you have a balanced extreme, you
can have 20 amps rms on the filament windings with 64 amp peaks due to
the way the filament DC is generated from the AC.
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post #178 of 314
8/2/09 at 10:12am
Forgot about the damn 5V tap... Looks like the Hammond units are a no go. With the spec in hand there might be something which fits the bill or perhaps adding a small filament transformer inside the chassis would work. A 4A Hammond unit is pretty small...
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post #179 of 314
8/2/09 at 10:41am
I have the exact same transformer on my MPX3 as thahertz does. So assuming in was wired for correct use, and not the incorrect way the Extremes seem to have been wired, since mine is not a "12V" model - no voltage switch, etc. -- it would seem to have enough current delivery to handle it's application:

272BX 95VA, sec. 300-0-300, DC ma 100, Fil.#1(rct) 5.0v @ 2a, Fil.#2(htr) 6.3v @ 3.0a.

3 amp delivery at 6.3V for heater current - even using 3 ECC32's which draw .9a, this would seem to be in spec.

Am I reading this correctly? I realize this doesn't mean my MPX3 might not have other issues...
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post #180 of 314
8/2/09 at 11:16am
WOW, this Mikhail guy is turning into the Madoff of tube amps.
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