Hi Jeremy,
Of course your preamp may clip during transients but question is will you notice it with your flea powered SET power amp clipping even earlier.
The preamp I'm currently using also has the volume control on it's output. The line stage tube is biased at -7V and I wouldn't feel comfortable with anything less, in fact I'd prefer a bit more headroom. My phono preamp - while averaging at about the same loudness as my CD - can spit out some awfully high transients.
Regards
Manfred
Not a contradiction IMHO. That nominal 3V (peek or RMS?) is the output level at 0dB. The average level of a typical CD is way below that and won't cause too much trouble.J Epstein said:
Of course your preamp may clip during transients but question is will you notice it with your flea powered SET power amp clipping even earlier.
The preamp I'm currently using also has the volume control on it's output. The line stage tube is biased at -7V and I wouldn't feel comfortable with anything less, in fact I'd prefer a bit more headroom. My phono preamp - while averaging at about the same loudness as my CD - can spit out some awfully high transients.
This Thomas guy is notorious for making sense.
Regards
Manfred
Folks,
sounds like you all know this guy Manfred, hmmmh ... who is he?
Anyway,
Welcome Manfred! ...
Jeremy,
no, no bloody German bashing , constructive help spiced with a lil'bit put-on i would call this.
I have had exactly this discussion with Manfred a while ago and although i am a heavy case of wishful think Ing., i abandoned my "gorgeous idea" of having 6900's fabulous sonic footpint in my linestage and settled on a 12B4A with gain 6 and an OPT and heaps of bias, 17V if i remember correctly. For exactly the reasons Thomas described.
For having the phono stage's gain adjusted to be almost compatible (should read: not killing the listener when input is switched from phono to CD and GC is forgotten to be turned CCW a bit) with CD gain if phono's max.output is +17dB and the cartridge hands out 5mV at 0dB.
Oh yes, and then i try out a Decca London which hands out 8.5mV lowest case and is reputed to have fancy non-linear overshoots and i am in trouble again with my linestage's headroom. Same situation as with Manfred's and Thomas' preamp, the GC at the output and the linestage and its OPT having to handle the full swing all the time.
Gosh, what glad am i to have Thomas and Manfred around to talk me out of such goofs like the 6900 one or to rub my nose into existence of other possible traps.
Even if you measure now all is OK (just ok but not much headroom) with 2V rms line input, please consider that phono can reach peaks of +17dB over 0dB=5cm/sec @ 1kHz without exposing the slightest audible distortion. Not hearsay, measured by yours truly.
So check your phono stage's output at 0dB and check whether +17 is ok before you relax.
sounds like you all know this guy Manfred, hmmmh ... who is he?
Anyway,
Welcome Manfred!
... Jeremy,
no, no bloody German bashing , constructive help spiced with a lil'bit put-on i would call this.
I have had exactly this discussion with Manfred a while ago and although i am a heavy case of wishful think Ing., i abandoned my "gorgeous idea" of having 6900's fabulous sonic footpint in my linestage and settled on a 12B4A with gain 6 and an OPT and heaps of bias, 17V if i remember correctly. For exactly the reasons Thomas described.
For having the phono stage's gain adjusted to be almost compatible (should read: not killing the listener when input is switched from phono to CD and GC is forgotten to be turned CCW a bit) with CD gain if phono's max.output is +17dB and the cartridge hands out 5mV at 0dB.
Oh yes, and then i try out a Decca London which hands out 8.5mV lowest case and is reputed to have fancy non-linear overshoots and i am in trouble again with my linestage's headroom. Same situation as with Manfred's and Thomas' preamp, the GC at the output and the linestage and its OPT having to handle the full swing all the time.
Gosh, what glad am i to have Thomas and Manfred around to talk me out of such goofs like the 6900 one or to rub my nose into existence of other possible traps.
Even if you measure now all is OK (just ok but not much headroom) with 2V rms line input, please consider that phono can reach peaks of +17dB over 0dB=5cm/sec @ 1kHz without exposing the slightest audible distortion. Not hearsay, measured by yours truly.
So check your phono stage's output at 0dB and check whether +17 is ok before you relax.
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