So I'm feeding out of my BP-25's tape out into a Meridian 221 A2D converter. This works just fine - but I'm curious as to what is coming out of the BP-25's tape outputs ? The max input for the Meridian is described in their lit as "Consumer audio standards -10DB" AND Maximum input level 2.2 V (rms). Since it's working undistorted and my previous limited experience with overdriving the input of a analog to digital converter is that it will sound REAL BAD. - assumption is the Bryston probably is below this level (either way you state it). But heck ya'll or Mike will know ?
Tape out signals are basically just a reflection of the source device that connects to the pre-amps inputs. The only modifications a tape out circuit provides is buffering to provide a separate impedance matched output. The signals do not pass through the amplification and volume control circuits. A quick look at the BP25 pre-amp schematic on the Bryston site shows just that configuration (Mr. Tanner can correct me if I'm wrong).
Your A2D specification of "Consumer audio standards -10DB" AND Maximum input level 2.2 V (rms)" is one of two audio standards (consumer and Pro).
Pro nominal levels of +4dBu calculates to 1.23volts RMS and Consumer nominal levels of -10dBV calculates to 316mvolts (0.316volts) RMS. These are nominal levels (think average). For example, the nominal pro level of +4dBu corresponds to 0dB on a VU meter.
Note these are nominal levels specs, as consumer level can reach peaks of +10dBV (3.16 volts RMS). Likewise, pro levels can reach 20dBu higher than nominal, equaling (12.3 volts RMS) so that headroom is built into the equipment to avoid clipping.
(note the difference between pro and consumer in that consumer levels use dbV and pro use dBu. The 0dBV reference level is 1 volt and the 0dBu reference level is 0.775 volts, so the dB levels aren't exactly equal between the two).
Anyway, if you plug a standard consumer CD into the preamp (at -10dBV RMS), then the TAPE OUT signal will simply follow and be at (-10dBV RMS) which is a standard consumer nominal level. The TAPE OUT circuit will buffer the signal and provide a nice low output impedance. As you say, if you start clipping, it will sound "REAL BAD".
brucek
