[Theo]

Hi Jim,

I've been listening to my new Castanet for over a week now.  Very quiet and definitely best of all the headphone amps I've used.  One quibble I have is the rather low range of gain compared to other headphone amps.  Connected to the Cornet2 (44dB) and a 6.5mV output cartridge and listening through an HD600, I need to turn the gain to 80-90% to get enough volume.  Is there an effective way to tweak up the gain in the Castanet without affecting the sonics of it?

Thanks in advance.

[hagtech]

Lucky you!  Ideally, you want the volume control at maximum.  Such will give lowest distortion and best possible sonics.

No chance of more gain in this design, though.  Is 100% not loud enough?  I run the 20XL into 20dB gain tranny or PICCOLO(~3mV into CORNET), and that will blast my head off at 80%.  Did you make any value changes to any of the caps or resistors?

jh

[Theo]

Lucky you!  Ideally, you want the volume control at maximum.  Such will give lowest distortion and best possible sonics.

No chance of more gain in this design, though.  Is 100% not loud enough?  I run the 20XL into 20dB gain tranny or PICCOLO(~3mV into CORNET), and that will blast my head off at 80%.  Did you make any value changes to any of the caps or resistors?

jh

I know my Cornet2 is built right because it sounded loud and has headroom to spare when fed thru my old headphone amp. 

If you can blow your head off feeding 3mV into the Castanet, something must be wrong with mine, because I am feeding 6.5mV from a Goldring G1042.  It may be optimal to turn the volume to 90%, but I see an issue when I use a 5mV cartridge or using a 40dB Bugle in between.

I built the Castanet using all stock parts, unless I'd bought a couple of wrong parts by mistake.  I don't think so but I should double check.  Other than double check the parts, what measurement can I make to confirm proper gain for a stock Castanet built?  Though, I'm not good at measuring circuits.   

[Theo]

I checked the list of caps and resistors I'd ordered from Digikey and found no errors.  I had also always  double checked a part before I installed it.  The trannies and chocks are stock Hammond.  So I'm assuming all parts are correct.  Tube is EH 6H30Pi Gold.

My last resort may be to check my ears, but I suppose the next step will be to do some measurement.  What do I measure to confirm gain?

[hagtech]

Perhaps "blow my head off" is a bit misleading.  I can actually listen at those volumes and not tire.  It doesn't wear me out.  At least with well recorded music (I have some hip-hop tracks that'll make ears bleed).  I'm just trying to say I can get really loud.  For me.  Most of the time I crank it up to 2:00 or even 3:00 on the volume knob.  That for me is quite loud, with all the bass power and dynamic slam one often looks for from hi-fi.

So I did an experiment tonight.  I plugged my HD600 into the LO jack.  It's only 3dB softer.  Hmmm, at first it almost seemed to sound better.  Slightly more clarity?  But I digress.  I played a piano version of Pachelbel's canon and cranked it up to 100%.  No distortion, no headroom problems.  Same sound, just louder (ok, using a DA-10 at this point).  I really wouldn't ever want to play this louder.  For me, this is cranking.  The best part, it was comfortable.  No fatigue.  It didn't hurt.  But yeah, I'd still say it was like blowing my head off.  When finished, I took the phones off and found no ear pain or ringing.  No reduction in sensitivity.  I could still hear normally.

Anyway, I then went to tuck my kids in bed.  They said "we heard you playing music".  Oy!  This was way down the hall, around the corner, two rooms away.  They were sitting in bed and heard my headphones.

I'm not sure how to test your volume.  Maybe if you have the HiFi News test LP you can play a reference level track and measure output of CASTANET with DVM on ac?  It puts out 4Vrms before clipping.

jh