corbato said:Hi Navin
What you doing up so late
As for your dilemma the solution is simple. Just don’t 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.
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.
Regards,
Ray
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.
Regards,
Ray
ray_moth said:
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.
EC8010 said:
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 prod.htm
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.
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.
Sherman said:
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.
ray_moth said:
the primary of the OPT I am looking at is 5k. The builder of this OPT claims it is used in UL/PP mode by Diva amps.
I intend to use it in PP/Pentode AB1 and PP/Triode AB.
from the mullard datasheet:
Ra=2k in Class A Pentode for 1 valve,
for 2 valves in PP 6.6K with screen grid tapping of 43%,
for 2 valves in PP 3.4K with fixed bias and cathode bias
Ra= 3K Class A Triode
for 2 valves in PP 5K at 400V
so from this is seems that i would need OPTs with a 3.4k primary or 6.6k primary. now i am confused. if I use the OPT in pentode AB1 what should be the ideal primary impedance? The supplier says he can wind a custom primary for me if i wish.
IMHO, given your stated intentions and the fact that you can get the OPTs wound to order, you should go for 6k plate-to-plate and use that same ratio for both UL mode (bass amp) and triode mode (treble amp).
UL will give close to pentode power and wil not reqire large amounts of NFB (20dB should be enough) to get a decent damping factor. Pentode, on the other hand, is a more difficult mode to design and build, because of its high OP impedance and the consequent need for a lot of NFB (26dB or more) to get an acceptable damping factor. The more NFB you need, the more challenging the design.
UL will give close to pentode power and wil not reqire large amounts of NFB (20dB should be enough) to get a decent damping factor. Pentode, on the other hand, is a more difficult mode to design and build, because of its high OP impedance and the consequent need for a lot of NFB (26dB or more) to get an acceptable damping factor. The more NFB you need, the more challenging the design.
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