Does the type of 5AR4 influence the sound?
- Thread starter cc43fan
- Start date
NOSValves
Super Member
Much depends on the power supply and how much decoupling the circuit has which in essence moves the audio circuit further away from the instantaneous performance of the rectifier tube.
For example a stock configured Dynaco stereo 70's with its anemic power supply filter configuration you are very likely to hear the difference between a nice fresh NOS Mullard and a modern produced Sovtek or JJ. If the power supply was re-designed and upgraded properly the chances are you would never hear the difference.
With the later situation the difference would be down to longevity, a nice fresh NOS Mullard could last you a life time. A Sovtek if you get a couple years out of it you're doing good. But then the Sovtek can be sourced for about 10% of the cost of a truly New Old Stock Mullard.
For example a stock configured Dynaco stereo 70's with its anemic power supply filter configuration you are very likely to hear the difference between a nice fresh NOS Mullard and a modern produced Sovtek or JJ. If the power supply was re-designed and upgraded properly the chances are you would never hear the difference.
With the later situation the difference would be down to longevity, a nice fresh NOS Mullard could last you a life time. A Sovtek if you get a couple years out of it you're doing good. But then the Sovtek can be sourced for about 10% of the cost of a truly New Old Stock Mullard.
cc43fan
I'll sleep when I'm dead
I'm currently using a sovtek, and I upgraded with SDS pwr board/VTA driver board. In the driver board I've got a 12au7 RCA cleartop in the center and RCA 12bh7's. For output tubes original Mullard EL34 (xf-2).
guitbanger
Active Member
I agree with what NOS said, I'd go ahead and pop for a NOS Mullard, you won't be sorry and you will have added peace of mind.
jaymanaa
RIP 1961-2018
My experience with Sovteks is they either fail fairly quickly, or last a very long time. Have you already tried different front end tubes? I find the 12BH7 to be a little "dark" for my taste.
cc43fan
I'll sleep when I'm dead
40-195-135-135uf up from stock 30-20-20-20. I bought SDS board and parts from triodeelectronics.com
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cc43fan
I'll sleep when I'm dead
I have tried 12au7's, but I don't have a very big tube inventory.
NOSValves
Super Member
I couldn't find any information on the tubes4hifi website in my brief look see. I'd bet its the stick configuration that those cap board have had for years, so you have minimal to gain Sonically from the use of a high dollar Mullard rectifier. But it would be much better longevity wise. Jay's comment was dead on with the Sovtek how long they will last is a luck of the draw type deal. But really that is the case with every modern production tube.
cc43fan
I'll sleep when I'm dead
Pretty sure the SDS PS board set ups come through Triode Electronics so you'd have to look there. I'm also pretty sure you are correct that they still use the same config they've been using for years.
NOSValves
Super Member
Yea you're all set.... in fact you could probably use one of those copper top SS 5AR4 simulators and not here any real degradation to the sound that could not be traced to the rise in voltage from the more efficient operation of the SS rectifiers. But the tubes and passive components will thank you with longer service life for using the slow start tube rectifier.
NOSValves
Super Member
Rex go take a look at the new setup! Now that is a nice upgrade from stock! Other then the quality of those miniature electrolytic caps I'm impressed. I've never been a believer in those dinky little things in tube gear.
cc43fan
I'll sleep when I'm dead
cc43fan
I'll sleep when I'm dead
Brilliant !
Shadowdog
Super Member
One low cost mod, is to add SS diodes in series with the 5AR4/GZ34 to help any new or NOS tube last while still keeping the slow warm up which is desirable in using that indirectly heated tube. Todays higher line voltages don't help the problem either!
It doesn't affect the sound quality and only costs a few cents more to use the UF4007 diode which is newer , faster, and quieter. This mod has been used for years by many for years with great success! The bigger amps put a higher load on the rectifier tube also.
It will also help save your rect. tube also if the power happens to flash off and on in quick succession.
I first read about it on diyaudio 3 yrs ago with Engineer Kevin Kennedy using it for 10 years at the time with no tube failures after.
This method of mounting the diodes takes advantage of the unused pins.
http://dynacotubeaudio.forumotion.com/t1006-tube-rectifier-diode-mod
Randy
It doesn't affect the sound quality and only costs a few cents more to use the UF4007 diode which is newer , faster, and quieter. This mod has been used for years by many for years with great success! The bigger amps put a higher load on the rectifier tube also.
It will also help save your rect. tube also if the power happens to flash off and on in quick succession.
I first read about it on diyaudio 3 yrs ago with Engineer Kevin Kennedy using it for 10 years at the time with no tube failures after.
This method of mounting the diodes takes advantage of the unused pins.
http://dynacotubeaudio.forumotion.com/t1006-tube-rectifier-diode-mod
Randy
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this is a public forum some opinions are allowed ya know
NOSValves
Super Member
Actually not sure when the Kennedy article was written but Quick Silver implemented that design in one of his mono block designs in the 80's. For all I know he came up with the idea from the same place as you. I can't remember if it indeed completely kept the slow start function intact? Have you actually tested the slow rise over a standard 5AR4 setup to compare if its identical? I'm sure you know this but a 5AR4 will very gently ramp up the voltage taking about 45 seconds total.
EDIT: PS just read that link and looks like a guy (or Mike @ QS) might be taking credit where it may not be do. I talked to Mike when I had one of his designs on my bench (not an 8417 based amp) and we discussed his SS/tube combination setup which at the time he took full credit for it. Ya just never know what to believe and what not to believe.
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