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A Very Compact Hybrid Amp - Page 110

post #1636 of 2213
Just snarfed' this (MID-FI?) :

"CTH: I'm actually listening to one as I'm typing this up. I only have low impedance phones these days, but this little guy is a KILLER with low impedance. It's at least mid-fi, not lo-fi. I'll have to compare it to a CK2III sometime."

from the NorCal Impressions

EDIT: anybody know who's CTH it was?
post #1637 of 2213
looks like the poster's, built by sachu. i completely spaced on this meet. i really wanted to hear the hd800 and hf2. oh well.
post #1638 of 2213
Quote:
Originally Posted by holland View Post

The + and - are taken from the same side (1 ground for that side). The DC on that one side should be offset within itself by the + and -. G is not attached, so the DC floats.

I guess a more apropro situation is this (and less confusing though they are the same), with the M3.


Your supposition was correct, Holland....

Balanced CTH proof of concept.
LL
post #1639 of 2213
It's already known that this design can be used as a 'tube tester' - a balanced version can be used as a 'tube comparator.' I actually have a 6N30 in one channel and a 12BH7 in the other right now

Completely gratuitous I know. If only my ears matched!
post #1640 of 2213
Quote:
Originally Posted by wiatrob View Post
It's already known that this design can be used as a 'tube tester' - a balanced version can be used as a 'tube comparator.' I actually have a 6N30 in one channel and a 12BH7 in the other right now

Completely gratuitous I know. If only my ears matched!
Ah, a man after my own heart...

Post details plz

Oh, and how's the 6n30?
post #1641 of 2213
The 6N30 remains one of my favorite tubes for this amp - plentiful and tight bass. The 12BH7 gives it a run for the money.

I'll post some build details soon, pretty straightforward though - almost exactly as in the M^3 diagram above. I have flaoting SG (case no case) and tied OG's from board to board. (My OG->SG V's measure within a few mV...)
post #1642 of 2213

Help!

I have just completed my cth and initially all the voltage readings were correct and the e12 functioning correcctly. After checking for a second time and messing around I believe some thing must have shorted. Corrently the e12 is not working and readings are as follows

ORand OL are 0V
OG is 12 V
heater 12V
TB+ is 110V
V across pins 1 and 6 is 0

Any help would be much appreciated but please keep it simple as I am a complete novice
post #1643 of 2213
Seems like Q4P and Q3P might be dead. Can you check the voltage at the emitter of Q4p and Q3P with respect to SG?
post #1644 of 2213
Welcome, but a sad first post! To double check, OR and OL measured from the pads on the PCB or the output jack?

When you are measuring pins 1 and 6, are these are measured from SG to pin 1 and SG to pin 6?

Quote:
Originally Posted by Ged View Post
I have just completed my cth and initially all the voltage readings were correct and the e12 functioning correcctly. After checking for a second time and messing around I believe some thing must have shorted. Corrently the e12 is not working and readings are as follows

ORand OL are 0V
OG is 12 V
heater 12V
TB+ is 110V
V across pins 1 and 6 is 0

Any help would be much appreciated but please keep it simple as I am a complete novice
post #1645 of 2213
I have had two CThs come back to me with issues.

1>One CTh suddenly seems to have stopped working. All voltages except for OR->SG, OL->SG seem to check out fine.
THis amp had 250 hour on it at least.
Only had time to take it apart oday..will poke around a bit more to see what's up with this amp, see what voltages are there on the splitter and the buffers and of course on the E12. (Dayton audio caps for C4R and C4L, with shunt modded alps Rk27)

2> The second CTH seems to be tripping whenever i go beond 2 o clock position on the volume knob. Need to figure out why.. (Jantzen audio caps for C4R and C4L)


Any ideas?
post #1646 of 2213
can you please tell me which one is the emitter?

wiatrob-OR andOL tested on pads
pins 1 and 6 tested with aprobe on each and tube fitted as described on cavalli.com
post #1647 of 2213
Quote:
Originally Posted by Ged View Post
can you please tell me which one is the emitter?

wiatrob-OR andOL tested on pads
pins 1 and 6 tested with aprobe on each and tube fitted as described on cavalli.com


Did you test across pins 1 and 6, i.e with the red lead on pin 1 and black lead on pin 6.
Or with the red lead (positive) on pins 1 and 6 and the black lead (ground lead) on SG on the board?
post #1648 of 2213
red on pin 1 , black on pin 6 tube fitted
post #1649 of 2213
Quote:
Originally Posted by Ged View Post
red on pin 1 , black on pin 6 tube fitted
Ok..that will give you 0 V as pin 1 and 6 are supposed to be at the same voltage potential.

Remember to measure all voltages with respect to SG. That is if you want to measure voltage on pin1 of the tube socket. PLace the red lead of the multimeter probe on pin1 and the black lead on SG (on the board). This will give you thevoltage at pin1. Then do the same for pin6.

OL and OR are similar as well...i.e red lead on OL/OR and black lead on SG.
post #1650 of 2213
pin 1 voltage relative to SG 108v
pin 6 voltage relative to SG 108v
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