Hmmm...With this transformer you don't have enough heater current for even one 6W6 at 6.3V. Again 2x400 is way too much. You would have to throw away too much energy and heat on RC to go down to 350VDC. Anyway if you get a 350V B+ somehow, you may try 12K//12K 5W each for plate load and 680R+680R in series for cathode bias for each 6W6GT.
Aha, it has enough heater current to the left. I did not look there, bcs they normally depict primaries. As for the other transformer, it has the same secondary HT, so nothing more to think.
It is for post #22. Again 22mA, I targeted. But its only speculation. I don't have 6W6GTs so to tell you more. Its up to you to verify with measurement if you gonna get 30V on cathode and circa 225V on anode (my targets for R values I gave) when you gonna put it together.
It is for post #22. Again 22mA, I targeted. But its only speculation. I don't have 6W6GTs so to tell you more. Its up to you to verify with measurement if you gonna get 30V on cathode and circa 225V on anode (my targets for R values I gave) when you gonna put it together.
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About new production valves.
I have been asked about using new production valves in this project. The answer is: No sonic degradation by using new production with this project. I got the chance to test an EH pair. They perform flawlessly with very good clarity and coherence. Best part is that microphonics are very very low. Seems that 6V6 is a very nicely behaving type as used here, just flavor changes, and the main performance envelope is always in frame. I will see about JJ 6V6s too, given a chance.
I have been asked about using new production valves in this project. The answer is: No sonic degradation by using new production with this project. I got the chance to test an EH pair. They perform flawlessly with very good clarity and coherence. Best part is that microphonics are very very low. Seems that 6V6 is a very nicely behaving type as used here, just flavor changes, and the main performance envelope is always in frame. I will see about JJ 6V6s too, given a chance.
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Finally got those JJ 6V6 on my hands, they look really nicely built, hope they sound as they look.
I’m in the process of finishing other projects at the moment so it will take some time to do this one. First also I’ll redo the 417A to a 12B4 this will also serve as a comparison bed. Gee, I’ve done so many toob lines during the years, but I’m missing the parallel 6922 now that I remember.
I’m in the process of finishing other projects at the moment so it will take some time to do this one. First also I’ll redo the 417A to a 12B4 this will also serve as a comparison bed. Gee, I’ve done so many toob lines during the years, but I’m missing the parallel 6922 now that I remember.
I was thinking of something more elaborate than only an Oring over the bases. Thought of a piece of thin marine plywood or PCB to mount both bases plus circuit and hang this board with 4 Orings from the main topboard or other hangers inside the box, Origs will hang a 45º towards the center of the subboard to limit movement, this way we may have more compliance for the suspension. Only connections to this board would be B+ Grd, input and output pairs. Maybe not the best option, we might find a better solution, but how does this sound to you? Other ideas?
Maida addition & 12B4 comparison
This is an update on the 6V6 line preamp.
Two things are new:
1. A Mosfet Maida regulator was added in the 6V6 preamp.
2. A comparison was performed against a 12B4 preamp. The 12B4 has Mosfet Maida too.
Results:
1. The Maida works well. Benefits 3D, bass slam, transparency, drops background noise. Thankfully it does not change the 6V6 line stage's tone. Tone remains as when with the passive PSU. The valve rectifiers feeding the Maida, are still audible for sound signature if rolled. Only less drastically so than with a passive PSU.
All in all the Mosfet Maida presents a worthwhile positive add on.
2. There is no comparison. The 6V6 beats the 12B4 stage easily. The 12B4 line stage sounds gray and shy compared to the 6V6 line stage. Musical information from bass to highest treble, is just so much more and it breaths when using the 6V6. Also dynamics are clearly better. I did not expect such an easy victory. I did the comparison with a DIYer friend present. He is the maker of the 12B4.
He draw the above conclusions only too fast. I was listening and not speaking for much longer. I draw the same conclusions.
He will modify towards 6V6 immediately he said.
*The 12B4 line stage is shown in the attached picture. RCA NOS 12B4s, Mundorf Silver Oil Supreme coupling, ditto for cathode bypass parallel on Silmics, great hook up coax.
This is an update on the 6V6 line preamp.
Two things are new:
1. A Mosfet Maida regulator was added in the 6V6 preamp.
2. A comparison was performed against a 12B4 preamp. The 12B4 has Mosfet Maida too.
Results:
1. The Maida works well. Benefits 3D, bass slam, transparency, drops background noise. Thankfully it does not change the 6V6 line stage's tone. Tone remains as when with the passive PSU. The valve rectifiers feeding the Maida, are still audible for sound signature if rolled. Only less drastically so than with a passive PSU.
All in all the Mosfet Maida presents a worthwhile positive add on.
2. There is no comparison. The 6V6 beats the 12B4 stage easily. The 12B4 line stage sounds gray and shy compared to the 6V6 line stage. Musical information from bass to highest treble, is just so much more and it breaths when using the 6V6. Also dynamics are clearly better. I did not expect such an easy victory. I did the comparison with a DIYer friend present. He is the maker of the 12B4.
He draw the above conclusions only too fast. I was listening and not speaking for much longer. I draw the same conclusions.
He will modify towards 6V6 immediately he said.
*The 12B4 line stage is shown in the attached picture. RCA NOS 12B4s, Mundorf Silver Oil Supreme coupling, ditto for cathode bypass parallel on Silmics, great hook up coax.
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Zen Mod said:
Not yet. I hope it will give even more music if I will. Please suggest your best preference shunt reg schematic for 330V B+
The two preamps are equivalent in concept with the particular 12B4 application having some more aces by using better hook up wire, Silver Oils over cathode lytics, separated PSU box, and a stepped attenuator.
Toobz Day
It was high time for a 6V6 tube comparison.
Two people, 6 tube pairs.
SPL constant, notes taken. Standard music. Standard listening positions.
Disclaimer: The following listening impressions are subjective, based on performances exclusive for the line stage described in this thread.
Tubes:
1. MOV / OSRAM 6V6G Coke bottle:
Melodic mid tone (euphonic coloration), soft bass, open but not harsh highs. A 'cozy' sound, not particularly clean. Microphonic enough.
2. Visseaux 6V6G Coke bottle:
Still melodic enough but noticeably cleaner than the MOV, good balance across the spectrum, firm but not big enough bass. Good microphonics for an ST bottle.
3. Sylvania 6V6GT VT107A:
Nice mid balance, close to neutral. Good bass. Soft, not open enough HF. Good microphonics.
4. Philips Miniwatt 6V6GT:
Great balance. Only a hint of mid tone romance. Clean and open but never harsh. Very good bass and microphonics.
5. electro-harmonix 6V6GT:
Open, clean, lean enough balance, deep bass not enough. Some hardness in the presence range. Not bad, catchy sound. Excellent microphonics.
6. Tungsol reissue 6V6GT:
Spot on neutrality. Proportionate sound, excellent analysis. No highlights, no harshness. Excellent microphonics.
Conclusions:
No bad 6V6 in the above list. Two stand outs: For NOS is the Miniwatt, for new is the Tungsol. The Miniwatt adds just a bit of euphonic expression in vocals and other midtones, posing as correct , clean and big, but alluring too. But the Tungsol reissue is the monitor tube. It has all the stuff needed and makes no statements.
Regards to all tubephiles
Salas.
It was high time for a 6V6 tube comparison.
Two people, 6 tube pairs.
SPL constant, notes taken. Standard music. Standard listening positions.
Disclaimer: The following listening impressions are subjective, based on performances exclusive for the line stage described in this thread.
Tubes:
1. MOV / OSRAM 6V6G Coke bottle:
Melodic mid tone (euphonic coloration), soft bass, open but not harsh highs. A 'cozy' sound, not particularly clean. Microphonic enough.
2. Visseaux 6V6G Coke bottle:
Still melodic enough but noticeably cleaner than the MOV, good balance across the spectrum, firm but not big enough bass. Good microphonics for an ST bottle.
3. Sylvania 6V6GT VT107A:
Nice mid balance, close to neutral. Good bass. Soft, not open enough HF. Good microphonics.
4. Philips Miniwatt 6V6GT:
Great balance. Only a hint of mid tone romance. Clean and open but never harsh. Very good bass and microphonics.
5. electro-harmonix 6V6GT:
Open, clean, lean enough balance, deep bass not enough. Some hardness in the presence range. Not bad, catchy sound. Excellent microphonics.
6. Tungsol reissue 6V6GT:
Spot on neutrality. Proportionate sound, excellent analysis. No highlights, no harshness. Excellent microphonics.
Conclusions:
No bad 6V6 in the above list. Two stand outs: For NOS is the Miniwatt, for new is the Tungsol. The Miniwatt adds just a bit of euphonic expression in vocals and other midtones, posing as correct , clean and big, but alluring too. But the Tungsol reissue is the monitor tube. It has all the stuff needed and makes no statements.
Regards to all tubephiles
Salas.
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'It has all the stuff needed and makes no statements.'
My experience exactly. I have a very small, wimpy power amp that uses 6V6s, and in my travels with my much more widely listend clientele, the Sovtek Tung-Sol is the mutha for ya. It adds less, subtracts less, interprets less, than any other.
The gray-paint RCA and Bendix Red Bank (it had another designation; 7408, maybe) sounded just as good (the Bendix perhaps just a little more tonally dense), but both had a lot more cathode-coupled (and unequally, so it would appear on the output) HUMM!
I hate hum.
The Tung-Sol does suffer from crooked bottles, though. Not too good, if your tubes are on display. I use those quads for my breadboards.
Aloha,
Poinz
My experience exactly. I have a very small, wimpy power amp that uses 6V6s, and in my travels with my much more widely listend clientele, the Sovtek Tung-Sol is the mutha for ya. It adds less, subtracts less, interprets less, than any other.
The gray-paint RCA and Bendix Red Bank (it had another designation; 7408, maybe) sounded just as good (the Bendix perhaps just a little more tonally dense), but both had a lot more cathode-coupled (and unequally, so it would appear on the output) HUMM!
I hate hum.
The Tung-Sol does suffer from crooked bottles, though. Not too good, if your tubes are on display. I use those quads for my breadboards.
Aloha,
Poinz