HI Russell,
Thank you.
I think it should work with a soft start board as the voltage of the switch would be lower if it is used
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I thought that in the F6 thread, it was said the output of BA3 was over 1000R, they were concerned with mating it to F6 input impedance? I have to say, it mates fine to mine!
Russellc
The F6 with the jfet input buffer should not have any problem. It would be
an issue if you want to drive the transformers directly.
an issue if you want to drive the transformers directly.
Considering it's meant to drive an F4 sans buffers (Burning Amp output stage), it would certainly drive the F6 w/buffers.
I was more interested in the output impedance with regards to driving headphones. I've seen some comments that the BA-3 makes a great headphone amp...but I haven't had that experience. With 32 ohm, very sensitive Grados the BA-3 lacks drive and requires 3/4 of the volume knob to get a good volume level. A 20-30db gain headamp with 45mA of bias should blast a pair of Grados off my head. Problem is the output impedance is so high (for a headphone amp) that it can't drive my 32R Grados and somehow the signal is swamped. Might work better with higher ohm headphones but it still is not ideal, I think.
I am speculating here, but the output impedance is probably one of the tradeoffs that occurs with this no feedback design. One could make a preamp with a similar topology (F5-like) with feedback and bring the output impedance down. Not that the BA-3 output impedance is really that high...in fact, it's fine for a preamp. Just not good for a headphone amp.
I was more interested in the output impedance with regards to driving headphones. I've seen some comments that the BA-3 makes a great headphone amp...but I haven't had that experience. With 32 ohm, very sensitive Grados the BA-3 lacks drive and requires 3/4 of the volume knob to get a good volume level. A 20-30db gain headamp with 45mA of bias should blast a pair of Grados off my head. Problem is the output impedance is so high (for a headphone amp) that it can't drive my 32R Grados and somehow the signal is swamped. Might work better with higher ohm headphones but it still is not ideal, I think.
I am speculating here, but the output impedance is probably one of the tradeoffs that occurs with this no feedback design. One could make a preamp with a similar topology (F5-like) with feedback and bring the output impedance down. Not that the BA-3 output impedance is really that high...in fact, it's fine for a preamp. Just not good for a headphone amp.
How important is:
matching of output devices?
are Hitachi 2SK216 & 2SJ79 a reasonably good substitute in this position?
[Anyone have a circuit for x2 pairs of 2SK226? (stereo)]
Many thanks.
matching of output devices?
are Hitachi 2SK216 & 2SJ79 a reasonably good substitute in this position?
[Anyone have a circuit for x2 pairs of 2SK226? (stereo)]
Many thanks.
just compare xconductance with originals
if that's different enough , you'll have different preamp
not saying better or worse , just different
if that's different enough , you'll have different preamp
not saying better or worse , just different
Thanks for that ZM.
I found - after edit time closed - a few remarks by Juma to virtually the same question. The questioner found that the sound was not very good, thin and similar to a cheap commercial Preamp. Perhaps I will have to find the correct Toshiba devices.
[Any ideas on a line pre for these Hitachis? I once had an ASR pre which used them and which would drive my old Impulse horns without a power amp!!]
I found - after edit time closed - a few remarks by Juma to virtually the same question. The questioner found that the sound was not very good, thin and similar to a cheap commercial Preamp. Perhaps I will have to find the correct Toshiba devices.
[Any ideas on a line pre for these Hitachis? I once had an ASR pre which used them and which would drive my old Impulse horns without a power amp!!]
What is the gain of the BA-3 preamp? I tried searching but couldn't find the answer. I apologize if this was somewhere obvious.
Nelson says it is 30dB, but reading this forum it seems to be much less then that...
Wow, that is quite a variance. lol
I'll have to wait til I build mine to see what the gain is. I'm using a 20v trafo, shooting for 25v rails.
I'll have to wait til I build mine to see what the gain is. I'm using a 20v trafo, shooting for 25v rails.
I was trying to get a handle on the gain as I'm trying to decide where to put my attenuator in the signal chain. It could go after source selection or after the gain stage, depending on the overall gain. It's an LDR-based attenuator called the Clone Note and could handle 10db but not 30.
well I forgot , and lazy to check ..... but I believe gain is in vicinity of 11 V/V , so aroundish 21db