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Misdirected and confused

peterh said:
I don't think you need the corner frequency to be 1.8 hz. A 0.22 uF cap is more reasonable.
Click to expand...
Direct measurement with the existing PAS2s 0.22uf coupler shows that, using 1 KHZ as 0db the reference, connectimg the PAS2 to the tape input of my SS Bench Amp. drops the output of the PAS2 at 20 Hz by 8db. Dynaco in their manual specifies that the PAS2 termination be 500K ohms or higher. Generally what the input level control for a TUBE amp would be. The PAS2 output is taken directly from the output of the tone controls which appears to be a backwards Bauxendal in a feedback circuit. Clearly the measurements prove the case.
 
If you load an original PAS2 with 40k , sure it will drop bass.
But i understood that you had built a cathode follower as output stage ?And as coupling cap used a 2.7uF
to a 40k sand amp ? That combination ( 2,7uF / 40k ohm) will have a corner at 1.8 hz
What config are we discussing ?
 
maxhifi said:
Hey, you sure about that? Manual says it has 20dB of gain on line inputs.. 20dB of voltage gain is a factor of x10 voltage gain.. Yes the tone controls do lose some gain, but there's a surplus of it before them, so the net result is still 20dB of gain you don't really need all of.

Considering a CD player puts out 2V and could on its own drive a power amplifier, it seems to me there's plenty of extra gain. Depending on your power amplifier, you may be able to lose 6 - 10 dB of gain without really noticing it.

With 65dB of gain for a moving magnet cartridge input, this should give you 7V RMS output with a cartridge capable of 4mV output. You could probably easily knock this down to. say. 1.5V out using a voltage divider and still be able to drive your power amplifier to clipping.

I think if the input resistor on the solid state power amplifier is in the 30k range, you could easily put 100k in series with the output of the PAS and still be able to get enough volts to drive your amplifier to clipping.

Another benefit to this method, is it substantially improves the noise floor of the system, which can really be a benefit if you use sensitive speakers.
Click to expand...


Direct measurement with the existing PAS2s 0.22uf coupler shows that, using 1 KHZ at 0db as the reference, connectimg the PAS2 to the tape input of my SS Bench Amp. drops the output of the PAS2 at 20 Hz by 8db. Dynaco in their manual specifies that the PAS2 termination be 500K ohms or higher. Generally what the input level control for a TUBE power amp amp would be. The PAS2 output is taken directly from the output of the tone controls which appears to be a backwards Bauxendal in a feedback circuit. Clearly the measurements prove the case. Gain at 1Khz is not an issue. The fact that there is no gain / isolation of the output after the tone controls is and that results in the 8db drop.
Just need to wait for the power transformer and chassis and the buffer will be built.
 
peterh said:
If you load an original PAS2 with 40k , sure it will drop bass.
But i understood that you had built a cathode follower as output stage ?And as coupling cap used a 2.7uF
to a 40k sand amp ? That combination ( 2,7uF / 40k ohm) will have a corner at 1.8 hz
What config are we discussing ?
Click to expand...


Yeah seems like you dropped in in the middle when I answered your question out of order.. I have not built it yet and was getting input on various ways to go. Ordered the little power transformer, filter and chassis. Probably get to building it this weekend
 
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