Hi Amperex,
This amp is for a friend and he's not an audiophile by any means, he just thinks my tube amp is cool and sounds great. So i guess he will be happy enough with a Hammond 1609 (10k) for the output, no oil caps and no expensive iron.
As for the Auricaps, yes, i've heard very good things and as i have only used orange drop before i am going to try them. So electrolitics,a choke , Hammond iron and EH tubes. Boutique parts will go for the resistors(kiwame) and the Auricaps.
One more question though: do you think a tube rectifier will improve the sound? The original amp uses silicon diodes and according to Poindexter it sounds great as it is.
Well, thanks for your help,
Al.
This amp is for a friend and he's not an audiophile by any means, he just thinks my tube amp is cool and sounds great. So i guess he will be happy enough with a Hammond 1609 (10k) for the output, no oil caps and no expensive iron.
As for the Auricaps, yes, i've heard very good things and as i have only used orange drop before i am going to try them. So electrolitics,a choke , Hammond iron and EH tubes. Boutique parts will go for the resistors(kiwame) and the Auricaps.
One more question though: do you think a tube rectifier will improve the sound? The original amp uses silicon diodes and according to Poindexter it sounds great as it is.
Well, thanks for your help,
Al.
Definitely do that. I replaced electrolytic coupling capacitors with AuriCaps in a solid state amp I built. They really do make a noticeable improvement.
For a PP amp, I'd say not, since the PS is out of the signal path due to cancellation at the xfmr center tap. For other applications, such as a guitar amp, the increased voltage drop at high currents may be beneficial. Otherwise, it won't make enough of a difference to be worth replacing the solid state with hollow state.
'do you think a tube rectifier will improve the sound
Hard to say.
I built the 'poinz' design amps with tube rectifiers (monoblocks) with a LCLC filtered power supply (converted Hammond 'G' amps). Different manufacture 5U4 & 5R4 rectifier tubes did sound different. I did use a dropping resistor on the 5U4 to maintain the same B+ voltage as the 5R4.
Anyways, this does not make any sense to me. Why would different rectifier tubes make a sonic difference? It does.
I can state the Sylvania 5R4GYB black plate with a 1/8" gap in-between plates was superior out of eight different rectifier tubes I auditioned. The Sylvania 5R4GYB with the 1/2" space in-between plates was slightly softer sounding, but still accurate. Perhaps the better rectifier if an amp sounds too bright on the top end.
BTW- I used four (parallel push-pull) 7C5 that is the same as a 6V6 in a loctal base. Phase splitter are the rare Raytheon 6CG7. The Siemens 6922 A0 code was very close in performance & much higher gain. The Siemens sonically outperformed the 5965 per our ears.
Hard to say.
I built the 'poinz' design amps with tube rectifiers (monoblocks) with a LCLC filtered power supply (converted Hammond 'G' amps). Different manufacture 5U4 & 5R4 rectifier tubes did sound different. I did use a dropping resistor on the 5U4 to maintain the same B+ voltage as the 5R4.
Anyways, this does not make any sense to me. Why would different rectifier tubes make a sonic difference? It does.
I can state the Sylvania 5R4GYB black plate with a 1/8" gap in-between plates was superior out of eight different rectifier tubes I auditioned. The Sylvania 5R4GYB with the 1/2" space in-between plates was slightly softer sounding, but still accurate. Perhaps the better rectifier if an amp sounds too bright on the top end.
BTW- I used four (parallel push-pull) 7C5 that is the same as a 6V6 in a loctal base. Phase splitter are the rare Raytheon 6CG7. The Siemens 6922 A0 code was very close in performance & much higher gain. The Siemens sonically outperformed the 5965 per our ears.
Attachments
Cool amp. Wish i could lay my hands on a chassis like that, i mean with that finish. Love it.
Parallel push pull ...umm, guess you were not happy with only 7 watts. I forgot to mention that my friend also needs good speakers and i am looking for a 93 dB driver so 7 watts for me is enough. Anyway once finished i already know it's not going to look as good as yours.
Al.
Parallel push pull ...umm, guess you were not happy with only 7 watts. I forgot to mention that my friend also needs good speakers and i am looking for a 93 dB driver so 7 watts for me is enough. Anyway once finished i already know it's not going to look as good as yours.
Al.
speakers
My Pro Ac 2.5s should have a power amp with 15-watts per channel. Speakers are about 90dB efficient.
I am building an 845 SET, triode 6550 PP and a 6c33c OTL amp. The best power amp stays plus one backup amp.
My favorite linestage to date is a simple 6P5GT. I am building one more linestage (preamp) with a phono preamp. I will also keep both of these as well.
My Pro Ac 2.5s should have a power amp with 15-watts per channel. Speakers are about 90dB efficient.
I am building an 845 SET, triode 6550 PP and a 6c33c OTL amp. The best power amp stays plus one backup amp.
My favorite linestage to date is a simple 6P5GT. I am building one more linestage (preamp) with a phono preamp. I will also keep both of these as well.
a bit over-optimistic on the power
"...guess you were not happy with only 7 watts."
You won't get 7 watts RMS from Poinz's amp. That's peak power - you might get 3.5W RMS.
Try it in simulation.
I built my own push-pull 6V6 triode-strapped amp, with a 300V B+, and the Hammond 1609 output, and I only got 2.25W RMS.
Joel
"...guess you were not happy with only 7 watts."
You won't get 7 watts RMS from Poinz's amp. That's peak power - you might get 3.5W RMS.
Try it in simulation.
I built my own push-pull 6V6 triode-strapped amp, with a 300V B+, and the Hammond 1609 output, and I only got 2.25W RMS.
Joel
That is probally correct 3.5 watts RMS & peaks of 7-watts with two tubes. I have enough headroom with PPP 6V6 (7C5) triode connected.
I also run the 6V6 at 330 volts plate & -25 volts bias. I was told the 30 volts over specification may short a tube, but no issues to date. The -25 volts bias does keep the tubes within plate dissipation spec, but may violate the screen dissipation spec. The screens do not have any color such as dull red & the tubes show no signs of becoming gassy.
I also run the 6V6 at 330 volts plate & -25 volts bias. I was told the 30 volts over specification may short a tube, but no issues to date. The -25 volts bias does keep the tubes within plate dissipation spec, but may violate the screen dissipation spec. The screens do not have any color such as dull red & the tubes show no signs of becoming gassy.
Yeah, i saw your schematic, cathode bias Poinz amp. It would be easier for me, but i have never tried fixed bias so i wonder if it makes much difference.
For a push pull it's not much,is it?Yeah, i read Poinz found some problems with only 315 volts at the screens. Well, once I had 300 volts at the screen of two 6w6's, maximun according to data sheets was 150 volts.Of course i didn't knew what i was doing, i asked in this forum because they were glowing blue and then found the screen dissipation was way beyond limits and corrected the problem, no more blue lights.
Still the sound was fantastic. Tubes are EXTREMELY forgiving, that's why i love this hobby.
Al.
Fixed vs cathode bias
I never tried cathode bias 6V6 triode. The poinz amp shounds incredable & I am not 'an easy sell', believe me. I tried cathode vs fixed bias on PP 45s and like the cathode bias better with a Solen 65uF poly cap bypass.
I think fixed vs cathode bias for best sonics depends upon the circuit design, tube used & simply sonic preference of the listener.
I never tried cathode bias 6V6 triode. The poinz amp shounds incredable & I am not 'an easy sell', believe me. I tried cathode vs fixed bias on PP 45s and like the cathode bias better with a Solen 65uF poly cap bypass.
I think fixed vs cathode bias for best sonics depends upon the circuit design, tube used & simply sonic preference of the listener.
Re: a bit over-optimistic on the power
thanks for runningthe sim Joel. I'll add one more thing, it is better( IMO ) not to run for max power.
It does not matter if it is an AB1, or A1 or A2...set things up so as to operate conservatively. 70% is the line in the sand that has served me well. If you want max power, you'll get the same of-the-rack commercialized BS that you can buy in BB or CC.
Also, I'd make the secondary recomendation to build with triodes if you want a triode circuit. If youwant to carry along that g2, you'd might as well put it to use. The 7233 and 6CK4 are examples on both sides of the triode connected 6V6 characteristic to play with. There are others, 5889, 421A, 7236 to name a few.
I for one do like the amps guilt to take advantage of the g2( and g3 ) better than those of with triodes...but it is a near thing sometimes.
cheers,
Douglas
Joel said:
thanks for runningthe sim Joel. I'll add one more thing, it is better( IMO ) not to run for max power.
It does not matter if it is an AB1, or A1 or A2...set things up so as to operate conservatively. 70% is the line in the sand that has served me well. If you want max power, you'll get the same of-the-rack commercialized BS that you can buy in BB or CC.
Also, I'd make the secondary recomendation to build with triodes if you want a triode circuit. If youwant to carry along that g2, you'd might as well put it to use. The 7233 and 6CK4 are examples on both sides of the triode connected 6V6 characteristic to play with. There are others, 5889, 421A, 7236 to name a few.
I for one do like the amps guilt to take advantage of the g2( and g3 ) better than those of with triodes...but it is a near thing sometimes.
cheers,
Douglas
I might be shot for this by some, but the usually quoted max. voltages are not an absolute maximum, as in that there will be "spitzensparken" etc. if it is exceeded in the least. It seems that the discussion is mostly about 6V6s as triodes. In that mode the screen (connected to the anode) max. voltage becomes that of the anode. One must remember that as a pentode, the screen must "survive" when its potential stays constant, as the anode goes to its lowest voltage of perhaps 30V during a cycle. At this point it draws significantly more current than when connected to the anode, where it (the screen) goes down in voltage with the anode.
A look at the specs with a triode 6V6 used as vertical deflection amplifier shows a max. voltage as high a 1200V. (Even the much smaller 6AQ5 allows 1100V.) Admittedly this is under pulse conditions, but it does show that there will not be sparking in the tube structure under these conditions. (This operation allows for a pulse duration of 2.5mS, long enough for sparking to occur if that was the limiting factor.)
Now I am certainly not advocating using just any voltage for amplifier purposes, but a 6V6 that shows internal leakage or sparking at the "low" voltage of say 350V, has something else wrong with it. One must also keep in mind that with cathode bias use, the odd 20V cathode voltage subtracts from the applied h.t. for what is actually over the tube. As others have indicated, the main thing is the dissipation under worst conditions, and keeping the G1 return resistor within the specified limit.
A look at the specs with a triode 6V6 used as vertical deflection amplifier shows a max. voltage as high a 1200V. (Even the much smaller 6AQ5 allows 1100V.) Admittedly this is under pulse conditions, but it does show that there will not be sparking in the tube structure under these conditions. (This operation allows for a pulse duration of 2.5mS, long enough for sparking to occur if that was the limiting factor.)
Now I am certainly not advocating using just any voltage for amplifier purposes, but a 6V6 that shows internal leakage or sparking at the "low" voltage of say 350V, has something else wrong with it. One must also keep in mind that with cathode bias use, the odd 20V cathode voltage subtracts from the applied h.t. for what is actually over the tube. As others have indicated, the main thing is the dissipation under worst conditions, and keeping the G1 return resistor within the specified limit.
Sorry folks, one more question.
Tubelab, you mention in your post (#13) the use of computer triodes. I have a design where I decided to use the moderately powerful E182CC twin triode as a driver, but I found a quite disturbing difference in mu between the triodes of some specimens. I am told that this is a shortcoming of computer tubes working on-off, as the Gm does not require to be closely matched.
Do you or any other member have any comments in this regard? (A little off-thread, but since the subject was mentioned....)
Tubelab, you mention in your post (#13) the use of computer triodes. I have a design where I decided to use the moderately powerful E182CC twin triode as a driver, but I found a quite disturbing difference in mu between the triodes of some specimens. I am told that this is a shortcoming of computer tubes working on-off, as the Gm does not require to be closely matched.
Do you or any other member have any comments in this regard? (A little off-thread, but since the subject was mentioned....)
I have done some cursory testing with 5963's, 5965's, 7044's, 6463's and a few others. I did find a few, with obviously mismatched sections, but I have fornd this other tube types as well, especially the 6AS7. I think that this effect may be lot related. I believe that most of the tubes that I have are used, and may be ALL from the SAME lot. I have about 500 GE 5965's with the SAME DATE CODE! This obviously blows the idea of "random sample" testing.
Some tubes, and the 6V6 appears to be one, can be severly abused without "sudden death". Look at what I did to a pair of poor 6AV5's in the thread where someone asked me to try them, 400 volts (triode strapped) on a 175 volt screen. These tubes sounded good. Fender (and others) abused the 6V6 a lot over the past 60 years. Most of them take it well.
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