Anyone built a tube-based (6BE6 or 6HS8) volume control?

GordonW · 23rd May 2008, 12:52 PM

I'm building a preamp... had originally planned to build the Marantz 7 circuit (simplified, no tone controls or loudness/rumble filter etc)... but after thinking and looking around, I'm thinking of making a change in the line stage (leaving the Marantz phono stage as original, though).

Has anyone here built one of THESE (tube-based volume control)?

http://home.netcom.com/~wa2ise/radios/6be6vol.html

My main question is- how quiet is it? Pentode partition noise? Hiss?

Also, how linear does it seem to be, passing sound at different volume levels?

Thanks!

Regards,
Gordon.

oldeurope · 24th May 2008, 07:39 AM

Hello Gordon,
you started an interesting thread.
At the moment I am making a tube based volume control, too.

I think noise is not the problem here, because the input level at
grid 1 is high and the anode load resistor fairly low to get no gain.
The main problem I see is only 50db attenuation. This is not enough.

In my project I need a phase inverter triode that has ideally unity gain.
I didn't find one, thus I am going to use the 6080 as an phase inverter.
I hope it makes no hum from the filament ...

Kind regards,
Darius

GordonW · 28th May 2008, 12:11 PM

I was looking at that... which got me thinking of using two 6BE6s per channel, for a total of 100dB attenuation. I'd think that would do it. This would also put the signal back in-phase...

After considering it further, my question, now, really is, what is the output gain at full-output from these? IOW, can I use two of these cascaded, to form a preamp line gain stage? Or, would I have to get additional gain somewhere else? If I have to add more tubes for more gain, it becomes far less attractive...

Regards,
Gordon.

oldeurope · 28th May 2008, 01:39 PM

Hi Gordon,

Quote:

Originally posted by GordonW
I was looking at that... which got me thinking of using two 6BE6s per channel, for a total of 100dB attenuation. I'd think that would do it. This would also put the signal back in-phase...
...

Yes.

Quote:

Originally posted by GordonW
...
After considering it further, my question, now, really is, what is the output gain at full-output from these? IOW, can I use two of these cascaded, to form a preamp line gain stage? Or, would I have to get additional gain somewhere else? If I have to add more tubes for more gain, it becomes far less attractive...

Regards,
Gordon.

you can increase the gain be increasing the 22KΩ resistor
at the anode.

Kind regards,
Darius

leadbelly · 28th May 2008, 04:11 PM

Look at: John Swenson's (In my eyes revolutionary) preamp!

GordonW · 28th May 2008, 05:59 PM

Anyone got a handle on how to calculate gain for a 6BE6 wired this way? I've been looking around, but I can't quite find the procedure... I can find data on the tube used as a converter or oscillator, but obviously, not wired like this...

If I just knew how to get the transconductance and effective plate resistance in THIS mode, I could take care of the rest, I think...

Regards,
Gordon.

oldeurope · 29th May 2008, 06:05 AM

Quote:

Originally posted by leadbelly
Look at: John Swenson's (In my eyes revolutionary) preamp!

Thanks for the link.

Darius

foboleyns · 29th May 2008, 02:11 PM

hey,

here is the circuit my used with a pair of chinese 6J2. 6AU6 be able to instead without modify.

oldeurope · 31st May 2008, 09:24 AM

Quote:

Originally posted by foboleyns
hey,

here is the circuit my used with a pair of chinese 6J2. 6AU6 be able to instead without modify.

Hello, thanks for your schematic.

I have two questions.
Can you hear the steps when adjusting the volume?
Why didn't you use a regulating pentode like e.g. EF83 6K7 6DA6 ... ?
I can't find any tube data for the 6J2.

Kind regards,
Darius

23rd May 2008, 12:52 PM	#1
GordonW diyAudio Member Join Date: Mar 2005 Location: Marietta/Moultrie GA	Anyone built a tube-based (6BE6 or 6HS8) volume control? I'm building a preamp... had originally planned to build the Marantz 7 circuit (simplified, no tone controls or loudness/rumble filter etc)... but after thinking and looking around, I'm thinking of making a change in the line stage (leaving the Marantz phono stage as original, though). Has anyone here built one of THESE (tube-based volume control)? http://home.netcom.com/~wa2ise/radios/6be6vol.html My main question is- how quiet is it? Pentode partition noise? Hiss? Also, how linear does it seem to be, passing sound at different volume levels? Thanks! Regards, Gordon. __________________ This is Gordon's Page: www.geocities.com/gordonwaters

24th May 2008, 07:39 AM	#2
oldeurope diyAudio Member Join Date: Mar 2008	Hello Gordon, you started an interesting thread. At the moment I am making a tube based volume control, too. I think noise is not the problem here, because the input level at grid 1 is high and the anode load resistor fairly low to get no gain. The main problem I see is only 50db attenuation. This is not enough. In my project I need a phase inverter triode that has ideally unity gain. I didn't find one, thus I am going to use the 6080 as an phase inverter. I hope it makes no hum from the filament ... Kind regards, Darius __________________ my password was hacked and my signature was modified, I am sorry. Please contact me via email. Radio-Darius(at)web.de http://oldeuropesblogs.blogspot.com/

28th May 2008, 12:11 PM	#3
GordonW diyAudio Member Join Date: Mar 2005 Location: Marietta/Moultrie GA	I was looking at that... which got me thinking of using two 6BE6s per channel, for a total of 100dB attenuation. I'd think that would do it. This would also put the signal back in-phase... After considering it further, my question, now, really is, what is the output gain at full-output from these? IOW, can I use two of these cascaded, to form a preamp line gain stage? Or, would I have to get additional gain somewhere else? If I have to add more tubes for more gain, it becomes far less attractive... Regards, Gordon. __________________ This is Gordon's Page: www.geocities.com/gordonwaters

28th May 2008, 04:11 PM	#5
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Look at: John Swenson's (In my eyes revolutionary) preamp! __________________ Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it. Stephen Leacock

28th May 2008, 05:59 PM	#6
GordonW diyAudio Member Join Date: Mar 2005 Location: Marietta/Moultrie GA	Anyone got a handle on how to calculate gain for a 6BE6 wired this way? I've been looking around, but I can't quite find the procedure... I can find data on the tube used as a converter or oscillator, but obviously, not wired like this... If I just knew how to get the transconductance and effective plate resistance in THIS mode, I could take care of the rest, I think... Regards, Gordon. __________________ This is Gordon's Page: www.geocities.com/gordonwaters


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