I don't think a gain factor of 15 is too much...
I am running a 2mv phono cartridge into a 36db phono stage w/a jfet BOZ as a preamp now. I wish I had more gain, actually. I've never pushed the amp into clipping and I have had the dial 3/4 of the way up or more. Typically it's 1/2 to 3/4 up. I don't listen real loud.
I am running a 2mv phono cartridge into a 36db phono stage w/a jfet BOZ as a preamp now. I wish I had more gain, actually. I've never pushed the amp into clipping and I have had the dial 3/4 of the way up or more. Typically it's 1/2 to 3/4 up. I don't listen real loud.
I always thought that you ned to match N and P in complementary topology to minimize distortions. Nelson mentioned it here that it is critical to match output devices in F5 to get the lowest distortions.
Here: http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-104.html#post3599007
Here: http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-104.html#post3599007
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So what to do with P3 if you don't have a distortion analyzer?
I just measured between the second leg of the pot and r4, put the pots about half way and made sure the channels were even. My Jfets are matched, Mosfets not matched. Got a better idea?
Also, I measured between middle leg of P1/P2 and the negative pcb hole of the electrolytic caps to insure the pots are zeroed (the caps aren't in yet) for startup. This correct?
Also (this might be a stupid question), I still need R2, the 47K input to ground resistor if I am going to put a volume pot in front of the board and use it as a preamp, right?
Regarding gain, yes...30 is a lot. I will try it stock and maybe go down if I feel like it's clipping early.
I just measured between the second leg of the pot and r4, put the pots about half way and made sure the channels were even. My Jfets are matched, Mosfets not matched. Got a better idea?
Also, I measured between middle leg of P1/P2 and the negative pcb hole of the electrolytic caps to insure the pots are zeroed (the caps aren't in yet) for startup. This correct?
Also (this might be a stupid question), I still need R2, the 47K input to ground resistor if I am going to put a volume pot in front of the board and use it as a preamp, right?
Regarding gain, yes...30 is a lot. I will try it stock and maybe go down if I feel like it's clipping early.
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yes PKI, I see it the same way.....
As far as I understood Nelson mentioned in the F6 thread the need to match the Vgs when you use two, three or more pairs within the polarity.
And in the case of F5 or F6 he recommended to take care not of the Vgs but the transconductance values if you want to influence the distortion spectra in a certain direction......
Means for lowest distortion of k2 and k3 dominance same transconductance. More transconductance on one side giving more k2 with positive phase when the higher transconductance is in the positive half.
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Hi guys, I am ordering boards to build BA 3 to use as a preamp for Aleph j and for F5 and am watching Hikari1's build with interest.
I see 6l6 comments on how to reduce gain by changing r13 so can tweek that I imagine to fit each amp/source.
I am not too knowledgable about the theory, but have build this hobby by just ordering the correct parts and soldering things together and learning curve is still going on. In this configuration using BA3 as preamp, do I need to order also bias boards from the store?
Thanks, John
I see 6l6 comments on how to reduce gain by changing r13 so can tweek that I imagine to fit each amp/source.
I am not too knowledgable about the theory, but have build this hobby by just ordering the correct parts and soldering things together and learning curve is still going on. In this configuration using BA3 as preamp, do I need to order also bias boards from the store?
Thanks, John
Got the chassis yesterday. I am starting to sort out placement. I need to order some volume/source extension shafts. I have a 25K ladder pot and a rotary switch I will use for source selection. No caps in the BA-3 yet, they currently reside in a jfet boz.
I will hopefully start drilling today. Still looking for a nice power switch for the front. Latching, pushbotton would be nice. Any recommendations?
If I can't find that I may use this rotary switch (see attached).
Also, should I be using an emi filter/iec inlet with EMI filter on this thing?
I will hopefully start drilling today. Still looking for a nice power switch for the front. Latching, pushbotton would be nice. Any recommendations?
If I can't find that I may use this rotary switch (see attached).
Also, should I be using an emi filter/iec inlet with EMI filter on this thing?
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For this BA 3 preamp, I am ordering stereo stepped attenuator from GlassWare audio, John has a 20K and 100K version, which one would you recommend?
Saw recommendation of 22v 22v transformer, would this be appropriate for GlassWare Biopolar power supply for solid state audio projects mentioned earlier in the thread by 6l6 I believe. New bipolar low-voltage power supply for solid-state projects
will change the caps for higher voltage caps.
Thanks, John
Saw recommendation of 22v 22v transformer, would this be appropriate for GlassWare Biopolar power supply for solid state audio projects mentioned earlier in the thread by 6l6 I believe. New bipolar low-voltage power supply for solid-state projects
will change the caps for higher voltage caps.
Thanks, John