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Old 23rd December 2005, 04:10 PM   #1
navin is offline navin  India
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Default 5 wire output transformer

MY OPT supplier claims he has never built an OPT for a triode amp before. but his OPT has the standard 5 wire primary (with UL). How does one know if the OPT can be used for triode?
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Old 23rd December 2005, 04:21 PM   #2
corbato is offline corbato  India
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Hi Navin
What you doing up so late

As for your dilemma the solution is simple. Just donít connect the UL taps of your OPT. I do assume your OPT meet the spec otherwise for a triode PP operation.

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Old 23rd December 2005, 10:50 PM   #3
navin is offline navin  India
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Quote:
Originally posted by corbato
Hi Navin
What you doing up so late

As for your dilemma the solution is simple. Just donít connect the UL taps of your OPT. I do assume your OPT meet the spec otherwise for a triode PP operation.

Merry Christmas to you and your family
Merry Christmas to you and your family too!

I am going to meet the OPT man today. He only speaks Chinese and I dont speak any so I am taking my Brother in Law with me.

He told us onthe phone that he does not know if his OPT can be used for Triode but it has the "standard 5 wire tap". Which wires are used for Triode in the standard 5 wire config and which are used for penode. He told us that the company he makes these OPTs for uses them in UL mode so he is sure they work for UL mode.
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Old 24th December 2005, 12:29 AM   #4
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Hi Navin,

Merry Christmas to you and to anyone else who may read this.

Load impedance requirements for UL and triode connection vary, depending on the tube type. However, in the case of the EL34, for example, the optimal load impedance is roughly the same (actually slightly higher for UL but that doesn't matter). Therefore, if you're using EL34s, as Corbato has already said, you can just use the primary winding without connecting anything to the UL taps. For other types of tube, you would need to check the tube specs.

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Old 24th December 2005, 12:31 AM   #5
EC8010 is offline EC8010  United Kingdom
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If this transformer manufacturer doesn't know whether his transformers can be used with triodes (much easier source; always makes any transformer look better) then he doesn't know what he is doing. Don't waste the money on the trip.
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Old 24th December 2005, 06:24 AM   #6
corbato is offline corbato  India
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Hi Navin

Perhaps due to language issues things are confused. He may have meant that he doesnít do OPTís for Triode SE use. Winding a Single End (SE) OPT is a very different ballgame. Not many can do this well. You may like to clarify this.

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Old 24th December 2005, 02:25 PM   #7
navin is offline navin  India
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Quote:
Originally posted by ray_moth

...However, in the case of the EL34, for example, the optimal load impedance is roughly the same (actually slightly higher for UL but that doesn't matter). Therefore, if you're using EL34s, as Corbato has already said, you can just use the primary winding without connecting anything to the UL taps...
Ok the OPT has 5 wires. I need to use 3 of them right? the taps are similar to those found here...
http://www.hammondmfg.com/1608.htm
I need 2 wired for pentode and 2 for triode.

Quote:
Originally posted by EC8010
If this transformer manufacturer doesn't know whether his transformers can be used with triodes (much easier source; always makes any transformer look better) then he doesn't know what he is doing. Don't waste the money on the trip.
he makes transofrmers for Divaamps and Zenn Audio amongst others so i guess he is reliable just afraid because i will be taking my trannys to india and if something goes wrong he will get a bad name.

http://www.divaaudio.com/diva/divapower.html
http://www.zenn.com.sg/Zenn%20prod.htm
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Old 24th December 2005, 02:56 PM   #8
Sherman is offline Sherman  United States
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It sounds as if his OPTs are PP not SE. They are not the same! The link you provided is to a PP OPT.

To try and answer a couple of questions-

Triode or pentode makes no difference to the OPT and no difference in the wires used on the OPT.

In a SE amp the B+ is connected to one wire of the trafo primary and the anode of the output tube is connected to the other. This is true regardless of whether the amp is wired in triode or pentode.

If the primary has 3 wires then the third wire is the UL tap.

With a SE amp using pentode output tubes you can wire the amp in triode mode or pentode mode. For triode mode G2 of the output tube is connected (usually via a 100 ohm resistor) to the plate of the same tube. The plate is then connected to the OPT.

In pentode mode G2 is connected to the B+. The plate is still connected to the OPT exactly as in triode mode.

If the OPT has a UL tap (not all SE OPTs do) then G2 can be connected to the UL tap (instead of the plate as in triode, or the B+ as in pentode). The puts the amp in "ultralinear mode" somewhere between triode and pentode.

Maybe you already knew all this and I apologize if I'm misunderstanding the confusion regarding the OPTs.
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Old 25th December 2005, 01:03 AM   #9
navin is offline navin  India
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Quote:
Originally posted by Sherman
It sounds as if his OPTs are PP not SE. They are not the same! The link you provided is to a PP OPT..
sherman you are absolutely right. it is for PP amps only. it has a 5 wire primary as show in the hammond link earlier. the amp the OPT is used for is the Diva amp's Blue Sky signature but Diva uses this OPT in pentode/UL mode so the builder of the OPT is not sure if the OPT can be used a PP Triode.

now if the OPT is used for Pentode/UL can it be used for Triode mode without modifications? the Power tube in an EL 34 PP.
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Old 25th December 2005, 11:36 PM   #10
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Hi Navin,

EL34 in PP requires approximately the following load impedance plate-to-plate:

Triode: minimum 5k; not critical, higer impedance will reduce both power and distortion

Ultralinear: 6k to 7k, the higer impedance will reduce both power and distortion

Pentode: 3.5k, critical.
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