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Old 15th August 2005, 09:21 AM   #11
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I'm interested in this project as well. Could someone recommend a few different output transformers? I'd thought about using these from Triode Electronics:

http://store.triodestore.com/tfchxfwi48oh.html

However, their bandwidth gives me a little concern. The price is right, and I'd like to give an inexpensive SE amp a try (my only other tube gear is the 11MS8 DIY amp from S5 and a 5687 hand-built preamp that I recently made).

Thanks!
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Old 15th August 2005, 11:05 AM   #12
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That OPT can't handle the current. It's only rated for 40mA if I read the specs correctly.
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Old 15th August 2005, 12:40 PM   #13
Sherman is offline Sherman  United States
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Quote:
Originally posted by motherone
...Could someone recommend a few different output transformers?...
Thanks!
As Mikael said those OPTs can't take the current. He biased at 75mA, mine are biased at 82mA.

For my amps I used the James 6123HS which can easily handle the current. I got them from Euphonia Audio and the price was basically the same as the Hammond 1628SE. I don't think you can do better for the price than the James trafos.
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Old 15th August 2005, 12:46 PM   #14
Sherman is offline Sherman  United States
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Default Re: Stereo power transformer for this amp?

Quote:
Originally posted by porkchop61
Ok-
I just found this thread on this project, and I'm going to build a stereo version of this amp.

My question is, can I use a Hammond 273BX for a stereo version of this amp? It's rated for 175ma not the 180ma...
Glenn
Glenn,

I put the meter to my amps to double check the actual values I'm running. I have 82mA on each of the output stages and 5mA on the input stages. That gives you 174mA total. If you bias the KT88's at 75mA as Mikael specifies in his schematic you'd be at 160mA.

You should be able to use that PTX as far as the rectified DC current is concerned. However double check the specs for the secondaries. Do the filament windings have enough current capability to run all the heaters? If so you should be good to go.
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Old 15th August 2005, 05:04 PM   #15
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Thanks for checking that Sherman.
The Hammond 270BX has 5.0V/3A, and 6.3V/5.0A CT taps so should be no problem.

The 6N1P takes 600mA (I'm only using one), and 2 KT88's take 3.2A, 5A available so no issues.

I've also heard that Hammond transformers do live up to their claim of "Conservatively rated".

I'd rather just buy one PT if you know what I mean

Thanks again!
Glenn
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Old 16th August 2005, 01:30 AM   #16
Sherman is offline Sherman  United States
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Quote:
Originally posted by porkchop61
...The 6N1P takes 600mA (I'm only using one)...

I'd rather just buy one PT if you know what I mean

Thanks again!
Glenn

Glenn,

I had forgotten that since you are building a stereo unit you do only need one 6N1P! It does look like you should be fine with that PTX.

I know what you mean about only buying one PTX. Iron adds up quickly (both in $$$ and in weight)!

Good luck and post your progress!
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Old 16th August 2005, 02:08 AM   #17
rdf is offline rdf  Canada
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Coincidentally, I was just on Euphonia's site. The James 6123HS isn't currently listed though James still lists it. Since these were bookmarked just moment's ago, here are some links:

http://euphoniaaudio.netfirms.com/ea...?cPath=26_1_33

And the James website (not the easiest to find, actually JIANSHIN ELECTRONICS CO):

http://jianshin.myweb.hinet.net/english_first.htm
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Old 16th August 2005, 12:16 PM   #18
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Oops, I think the choke may be a problem as it's only rated for 150mA (Hammond 193D).
Anyone make a higher current choke in 8 Henries?
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Old 16th August 2005, 02:58 PM   #19
Sherman is offline Sherman  United States
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Quote:
Originally posted by porkchop61
Oops, I think the choke may be a problem as it's only rated for 150mA (Hammond 193D).
Anyone make a higher current choke in 8 Henries?

The 8H value isn't critical and you could go higher without any problem. Hammond has a 10 Henry 200mA choke (193J) and a 10 Henry 500mA choke (193Q) both of which would work fine and happen to be on sale at Angela (not associated with Angela except as a satisfied customer).

Alternatively you could go with a lower Henry value and add an LC section to the PS.
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Old 16th August 2005, 04:26 PM   #20
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Quote:
Originally posted by Sherman



The 8H value isn't critical and you could go higher without any problem. Hammond has a 10 Henry 200mA choke (193J) and a 10 Henry 500mA choke (193Q) both of which would work fine and happen to be on sale at Angela (not associated with Angela except as a satisfied customer).

Alternatively you could go with a lower Henry value and add an LC section to the PS.
Thanks Sherman.
I think I'll go with the 10 Henry 200mA.
And oh yes, Angela is my favorite vendor for Hammond stuff. I'm also a satisfied customer.
Glenn
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