hello all.
I installed the new LL1663AM/PP Lundahl transformers. Already have over 200 hours of work, but still not burning up. The result is very good. The sound is more fluid, dynamic and natural. High are much more. Already heard the noise of the recordings. The process of burn-in is obviously very long for transformers with amorphous core.
Initially sounded really like a steel core transformers. But the truth is quite different.
Currently still far from final burn-in. By turning on the amplifier, the first 1-1.5 hours sounds a bit tight, then the sound becomes clear with more Hi and little medium, bass is gone. After a further 2 hours the sound becomes balanced by the bottom to the top.
I'm still waiting to see the final result of the burning-in process.
I installed the new LL1663AM/PP Lundahl transformers. Already have over 200 hours of work, but still not burning up. The result is very good. The sound is more fluid, dynamic and natural. High are much more. Already heard the noise of the recordings. The process of burn-in is obviously very long for transformers with amorphous core.
Initially sounded really like a steel core transformers. But the truth is quite different.
Currently still far from final burn-in. By turning on the amplifier, the first 1-1.5 hours sounds a bit tight, then the sound becomes clear with more Hi and little medium, bass is gone. After a further 2 hours the sound becomes balanced by the bottom to the top.
I'm still waiting to see the final result of the burning-in process.
The two output transformers on Evgeni's VTA ST-70 are USA made. They are made with M6 grain oriented silicon steel laminations. The primary and secondary windings are interleaved layer wound. They are "clones" of the original Dynaco A-470 output transformers.
Bob Latino
Maybe try to get the DCR down as low as possible like close to 20 ohms and lower even some are saying on different Forms for less resistance in the PS. Those where SE or SET amps, but I noticed all the old high end PP amps or ones that are well like today have the above in their PS or no choke. I'm thinking of the Harman Kardon Citation Amps (around 1H Choke under 10 ohms) and the Eico HF-12/14/81 and some Heathkits PP with No chokes.
Edcor makes affordable around 20 ohm and lower DCR 300-400 mA ones in 1-2H. There are for sure ones for a lot more money with higher H numbers , but it may not be noticeable in a PP amp.
The stock Dynaco choke has been said to be on the small side and a higher mA one should help , but try to get the DCR to close to 20 ohms or less as said. See if you notice a difference!
One inexpensive thing to try on that note is to Jumper the choke out as many PP amps don't have one. (reset the bias a bit lower to compensate for the bit higher B+ you will get though). Then see if the dynamics of the amp are improved as some say will happen.
Another improvement is to change some resistors on your VTA high gain (12AT7 tubes) PCB to the low gain board ones which will allow you to run 12AU7 type tubes like the better 12BH7A in some positions also . Bob later sold a low gain board which has been found to be better for most situations and that's all he sells now. Instructions are on his tubes 4hifi Form.
Edcor makes affordable around 20 ohm and lower DCR 300-400 mA ones in 1-2H. There are for sure ones for a lot more money with higher H numbers , but it may not be noticeable in a PP amp.
The stock Dynaco choke has been said to be on the small side and a higher mA one should help , but try to get the DCR to close to 20 ohms or less as said. See if you notice a difference!
One inexpensive thing to try on that note is to Jumper the choke out as many PP amps don't have one. (reset the bias a bit lower to compensate for the bit higher B+ you will get though). Then see if the dynamics of the amp are improved as some say will happen.
Another improvement is to change some resistors on your VTA high gain (12AT7 tubes) PCB to the low gain board ones which will allow you to run 12AU7 type tubes like the better 12BH7A in some positions also . Bob later sold a low gain board which has been found to be better for most situations and that's all he sells now. Instructions are on his tubes 4hifi Form.
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I am able to connect the choke windings in parallel. Then I will get next option:
1. 5H, 200mA, 15 Ohms , Saturating current 290mA
2. 3.75H , 280mA, 15 Ohms, Saturating current 400mA
3. 2.5H, 300mA, 9 Ohms, Saturating current 430mA
But I don't know what is better - more Henri or lower DCR.
PS. Bob thanks for answer, but I want to make from my Dynaco realy Hi-End amp. I hope I can.
1. 5H, 200mA, 15 Ohms , Saturating current 290mA
2. 3.75H , 280mA, 15 Ohms, Saturating current 400mA
3. 2.5H, 300mA, 9 Ohms, Saturating current 430mA
But I don't know what is better - more Henri or lower DCR.
PS. Bob thanks for answer, but I want to make from my Dynaco realy Hi-End amp. I hope I can.
Bob's latest PCB's incorporate CCS that you might be able to add on a small perf board under the chassis. He might give you the schematic. Another option is K & K audio CCS on very small PCB's which incorporates a fancier CCS.
If you just want to buy Bob's latest PCB with the CCS he also has a new Octal Tube version which many prefer and I would try it if I was in your situation.
If you just want to buy Bob's latest PCB with the CCS he also has a new Octal Tube version which many prefer and I would try it if I was in your situation.
I vote for the lower DCR plus you get a higher mA!
Maybe the middle one would be a good compromise as you get the higher mA than the stock Dynaco choke plus still the low DCR.
I think Bob is right that you probably won't notice the higher H's difference though.
But maybe those Hi- End OPT's will tell you which is better, and that's why I thought the middle one might be a good compromise to try!
Maybe the middle one would be a good compromise as you get the higher mA than the stock Dynaco choke plus still the low DCR.
I think Bob is right that you probably won't notice the higher H's difference though.
But maybe those Hi- End OPT's will tell you which is better, and that's why I thought the middle one might be a good compromise to try!
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Last night I installed the new Mundorf capacitors.
Is too early to say the end result of sound, but for now sounds pretty balanced from top to bottom with better dynamic and layering of music.
I keep thinking about choke. This will be the last upgrade that I can do.
Is too early to say the end result of sound, but for now sounds pretty balanced from top to bottom with better dynamic and layering of music.
I keep thinking about choke. This will be the last upgrade that I can do.
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