[Yoda]

Since the chime has a separate analog stage to provide gain for the Hagdac, could another selector switch be built in to select between the Hagdac output and volume control to add analog inputs?  I know that the 30db of gain would be pretty high for line level component, so maybe the analog side would have to be carefully attenuated to match levels (or other compromises)?  I'm interested in building a minimal one box solution that would compliment my cornet II and run directly into my amp. I've used the 'travelling' Chime directly to my amp and thought it was fantastic.

Matt

[hagtech]

+30dB gain is insanely too much for a linestage.  Typically, a linestage provides negative dB, or attenuation.  An average line level from a source component is high enough to drive most amplifiers into clipping.  Put it this way, your volume control would be set to maybe -36dB when totally cranked up.

Sure, it is possible.  It might even sound good.  If you must, then I'd suggest dropping the input by 30dB or so right after the selector switch and before a volume control.  Doing so will make things feel right, and could possibly add a bit of warmth to a stale source.

jh

[Yoda]

To attenuate 30db, I found this equation:

+Line level (input) -----R1----+-- +Line level (output)
                                         |
                         +----R2----+
                         |
Ground (input)----+--------------- Ground (output)

The attenuation of the circuit is determined by equation:

attenuation (in dB) = 20 * log10 ( (R1 + R2) / R2 )

Plugging in 30db attenuation and an R2 value of 100 ohms, R1 is 3.062 Kohms, where the closest standard value for R1 appears to be 3.09 Kohms 1% +/-

Sound reasonable?  I kind of like running everything through one box, but would it be wiser to consider the following option: I could just build a selector box and attenuate my sources directly:  Chime built in attenuation, Cornet II  which could be attenuated directly per recent post here, and Yamaha t-1 tuner, which has a variable output.

Matt

[hagtech]

That attenuator would present a 3k load to the sources (like C2).  That's a difficult load for them to drive.  Better to keep it in the 10k to 100k range.

jh

[Yoda]

OK, I'll rework that....

looks like if R1 = 100kohms, then R2 = 3.166 kohms, +/-

Matt

[hagtech]

Really, you don't need that kind of accuracy.  The gain is something like 30dB.  Maybe it's 28dB.  Ten percent tolerance on the resistor nominals is fine.

jh

[Yoda]

Just a follow up...after discussing this idea w/ JH, it seemed backwards to attenuate, then amplify back to line level.  He recommended using a buffered linestage.   Castanet parts, a large chassis and selector switch are all arriving in the mail....