I have some of Bas’s Aikido PCBs, to feed a horn system I’m assembling that will have a max dB of about 117 dB.
(I was going to use an autotransformer volume control www.intactaudio.com/atten_FAQ.html, but they don’t provide enough attenuation.
So I’ll use a stepped attenuator, for which attenuation is still less than an ordinary pot . . )
So: I want to build an Aikido pre, that other things being equal has the *minimum amount of gain. Gain = Half the first tube
What really good sounding tube has the *minimum amount of gain?
Thanks
Richard
(I was going to use an autotransformer volume control www.intactaudio.com/atten_FAQ.html, but they don’t provide enough attenuation.
So I’ll use a stepped attenuator, for which attenuation is still less than an ordinary pot . . )
So: I want to build an Aikido pre, that other things being equal has the *minimum amount of gain. Gain = Half the first tube
What really good sounding tube has the *minimum amount of gain?
Thanks
Richard
rick57,
Goto and look at the last page...
Aikido tubes: results and values
http://www.tubecad.com/2006/05/blog0064.htm
Alain.
Goto and look at the last page...
Aikido tubes: results and values
http://www.tubecad.com/2006/05/blog0064.htm
Alain.
6AS7 and 6BX7 are both octals
the
6GM8 and 6H30 are nine pin tubes
the "first tube" in the aikido really determines the gain. The second one is a cathode follower and all have slightly less than a gain of 1 (except for the 6AS7 which is bit lower).
So BALLPARK figures
6AS7=2
6BX7=5
6GM8=7
6H30=8
So the answer would be.
IF 9 pin THEN 6H30 OR 6GM8
END IF
I don't know how available the 6GM8 is though.
IF octal THEN 6BX7 OR 6AS7
END IF
Since the 6AS7 has a hefty filament current I would go for the 6BX7 but..YMMV
But if you really want MINIMAL gain..use the 6AS7 in first position and maybe something with less current hungry filamant as cathode follower...you would be using an insane amount of heater filament current for a preamp if you would use 4 6AS7's.
the
6GM8 and 6H30 are nine pin tubes
the "first tube" in the aikido really determines the gain. The second one is a cathode follower and all have slightly less than a gain of 1 (except for the 6AS7 which is bit lower).
So BALLPARK figures
6AS7=2
6BX7=5
6GM8=7
6H30=8
So the answer would be.
IF 9 pin THEN 6H30 OR 6GM8
END IF
I don't know how available the 6GM8 is though.
IF octal THEN 6BX7 OR 6AS7
END IF
Since the 6AS7 has a hefty filament current I would go for the 6BX7 but..YMMV
But if you really want MINIMAL gain..use the 6AS7 in first position and maybe something with less current hungry filamant as cathode follower...you would be using an insane amount of heater filament current for a preamp if you would use 4 6AS7's.
Hi Rick
I gave a look at your link and found this question and answer
Q - what if I need more than 42db of attenuation.
A - Custom units can be wound to 54dB of attenuation. Note that that is a 500:1 stepdown and may compromise the performance slightly. If you require that much attenuation you might want to examine the gain structure of your system.
Isn't there a possibility in your system to reduce gain?
Erik
I gave a look at your link and found this question and answer
Q - what if I need more than 42db of attenuation.
A - Custom units can be wound to 54dB of attenuation. Note that that is a 500:1 stepdown and may compromise the performance slightly. If you require that much attenuation you might want to examine the gain structure of your system.
Isn't there a possibility in your system to reduce gain?
Erik
Hi Rick57
I understand you want to use your Aikido board, but unfortunately this project involves gain (distortion and noise) that you don't want and don't need. Using 4 6AS7 tubes seems like complete overkill to me...your preamp will consume more power than your power amp.
I think it is possible to use just the second part of the aikido stage (the cathode follower). You will need an extra capacitor for this... An other option is, if you are using a DIY DAC with low output voltage, to use the gain of the Aikido to amplify this low signal to an adequate one. I plan to use a setup like this myself...some day
Erik
I understand you want to use your Aikido board, but unfortunately this project involves gain (distortion and noise) that you don't want and don't need. Using 4 6AS7 tubes seems like complete overkill to me...your preamp will consume more power than your power amp.
I think it is possible to use just the second part of the aikido stage (the cathode follower). You will need an extra capacitor for this... An other option is, if you are using a DIY DAC with low output voltage, to use the gain of the Aikido to amplify this low signal to an adequate one. I plan to use a setup like this myself...some day
Erik
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