I bought this years ago, didnt use it much because I didnt care for the sound. Came with 2 Sovtek 12ax7s. Recently swapped one with an old Raytheon, and it sounded light years better. My question: can I use any other tubes besides possibly 12at7 or 12au7? What about 12fq8? Im interested in "exotic" flavors of distortion. Sorry, I tried to find a link to a schematic, but was unable.
a.r.t. mpa tube pre amp
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tentoze
Twangophile
goldear
Certifiable Audio Junkie
There are a number of tubes that are pinout compatible with the 12ax7. However, many of these have radically different electrical characteristics, and are not a good idea to try.
However, the following are all 100% compatible, and are considered to be essentially the same tube: 12ax7, 12ax7a, 12ax7wa, ecc83, e83cc, 7025. Another that is about 70% compatible, but that has significantly lower gain is the 5751.
The 12AU7, 12AT7, 12AY7, 12AZ7 are all pinout compatible, but should NOT be used in a 12AX7 circuit. Doing so could potentially damage either the tubes, or the circuits, and may or may not produce sound, depending upon exactly how the circuit it biased.
"Tube rolling" is the long practiced art of swaping different makes of tubes, but usually for the same basic type of tubes. The differences in sound between two tubes with the exact same designation, but made by different manufacturers can be shocking in my experience.
So stick with the above list, and try tube from different manufactures. My personal favorites of the new stock 12ax7s are the EI 12AX7s, but tastes vary, so you may or may not like these at all.
Good luck!
However, the following are all 100% compatible, and are considered to be essentially the same tube: 12ax7, 12ax7a, 12ax7wa, ecc83, e83cc, 7025. Another that is about 70% compatible, but that has significantly lower gain is the 5751.
The 12AU7, 12AT7, 12AY7, 12AZ7 are all pinout compatible, but should NOT be used in a 12AX7 circuit. Doing so could potentially damage either the tubes, or the circuits, and may or may not produce sound, depending upon exactly how the circuit it biased.
"Tube rolling" is the long practiced art of swaping different makes of tubes, but usually for the same basic type of tubes. The differences in sound between two tubes with the exact same designation, but made by different manufacturers can be shocking in my experience.
So stick with the above list, and try tube from different manufactures. My personal favorites of the new stock 12ax7s are the EI 12AX7s, but tastes vary, so you may or may not like these at all.
Good luck!
Last edited:
Kegger
R.I.P. 1/12/1966 - 6/1/2017
Either 5751 as Goldear mentioned or pretty much any vintage 12ax7 will be better sounding
tubes then those sovteks.
Where abouts are you located? You may have an AK'er near by that could hook you up!
P.S. If you redo your info on this site and put in your local it will show up in the top right corner.
tubes then those sovteks.
Where abouts are you located? You may have an AK'er near by that could hook you up!
P.S. If you redo your info on this site and put in your local it will show up in the top right corner.
goldear
Certifiable Audio Junkie
I'm not very fond of the Sovtek 12ax7s that I have tried. The EIs, however sound gorgeous! I recommend trying to get yourself some EI 12AX7s, as they are the best sounidng new-stock 12AX7s that I personally have heard. 5751's can be a good sounding replacements for 12AX7s too, except inside phono sections, which usually require the full gain of a 12AX7 to work correctly.Kegger said:
I'm not familiar with the other tubes that you mention, so I can't offer very much help there.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
goldear said:
Couldn't agree more! I have tried both the EI 12ax7 and the EI el84's with very impressive results,
but to me the sovtek 12ax7's are turds! For a Good priced/bang for the buck tube look for NOS RCA
12ax7's as there prices havn't gone though the roof yet but offer very good sonics.
I know nothing of the 12fq8, Sorry!