No, nor would I ever attempt to. The laminations in a good opt are very carefully stacked before varnishing. Re-gapping, by definition, requires a degree of disturbance to the lams (including breaking the varnish seal), which must be carefully re-aligned afterwards.
I do not possess the necessary skills to attempt this procedure, which if carried out by a novice has the potential to ruin a transformer's performance. I would suggest to leave well alone unless you really know what you are doing and have successfully carried out this procedure on a number of cheap transormers beforehand.
Please seek the advice of more knowledgeable and skilled forum members who are experienced in building their own output transformers should you wish to pursue this idea any further.
I do not possess the necessary skills to attempt this procedure, which if carried out by a novice has the potential to ruin a transformer's performance. I would suggest to leave well alone unless you really know what you are doing and have successfully carried out this procedure on a number of cheap transormers beforehand.
Please seek the advice of more knowledgeable and skilled forum members who are experienced in building their own output transformers should you wish to pursue this idea any further.
Thanks for all the help. I will first build the amp with LL1623, 60ma. If all goes well, will try a Silk or perhaps Toroidy (Polish) out of curiosity.
Wish me luck, guys. First tube amp build 🙂
Wish me luck, guys. First tube amp build 🙂
Depending on the OPT it can sometimes be possible. I have done it once already and it worked very well. Its not always as complex as you might think.
ian
I am using the 307A as a single ended pentode - and it is performing wonderfully.
RH Amplifiers: RH-307A v2 "Super"
OPTs are from a german company Ritter, but Lundahls also have also worked well.
RH Amplifiers: RH-307A v2 "Super"
OPTs are from a german company Ritter, but Lundahls also have also worked well.
I am using the 307A as a single ended pentode - and it is performing wonderfully.
RH Amplifiers: RH-307A v2 "Super"
RH Amplifiers: RH-307A v2 "Super"
I've had the 307A tubes for this build for ages, but have not gotten around to building the RH-307A V2. Honestly, the RH84 using the Sony TC-500A Tamradio output iron has kept me quite satisfied. I know that the transformers are pretty small, at 600grams, but the amplifier is everything Alex says it is when using quality tubes.
I guess I'm wondering if it's worth the expense and effort to build the RH307A vs just keeping the RH84. I've literally put it off for years.
Incidentally, I just got a nice Loftin-White 2A3 amplifier with Electra-Print iron. The DHT sound is pretty amazing, but I can't help but compare it to my RH84. Despite the DHT sound cloud, the RH84 has fewer deficiencies and can be played with any genre of music successfully.
In any case, I'd welcome opinions from those who may have both the RH84 and RH307A builds.
I guess I'm wondering if it's worth the expense and effort to build the RH307A vs just keeping the RH84. I've literally put it off for years.
Incidentally, I just got a nice Loftin-White 2A3 amplifier with Electra-Print iron. The DHT sound is pretty amazing, but I can't help but compare it to my RH84. Despite the DHT sound cloud, the RH84 has fewer deficiencies and can be played with any genre of music successfully.
In any case, I'd welcome opinions from those who may have both the RH84 and RH307A builds.
I'm using Sony Tamradio OPTs. Same idea of a high gain output tube but I use EL12 and its variants in triode, gain of 18. So my driver tube is a DHT, and currently a 10Y which is marvellous. Great combination. I like to put the DHT first in the chain - no 9 pin valves here. You could do that with a EL84 in SE or PSE.
I have really good experiences with Toroidy. I have both the 1663, and the 1642 from Lundahl and the toroidy really gives him a run for their money! I have the single ended toroid for EL 84 tubes, and the one for el34
About the Toroidy transformers, I don't really get it. For EL84 or 6V6, nominal power 30 W, nominal current 150 mA. If those numbers were halved it seems more credible. Anyone have an opinion?
I actually asked the same question several years ago, to confirm the parameters of the EL84SE option, because I wanted 8K for a different application requiring 25W+. I never got the answer. Here is what I asked to confirm:
B+ 640V
Iq (quiescent current for single ended ) 120mA
Ip (peak current, 1khz signal) 230 mA
Vpp (Voltage swing, peak-to-peak, 1khz, 1100V)
Max RMS power 30W with 8ohm load.
They are completely different transformers to normal EI transformers. They are achieving the so-called gap with a special core material and so the specifications are quite different. I have used their transformer for EL 84s with KT 88 with no problem 80 mA 490 V, sounds great, so you have to take that into account. I can only recommend them especially for the price.