[stringgz301]

I found that the Amperex a-frames biased significantly differently from all my other tubes.  You may need to recheck it after installing the Tele's.

 

[BK_856er]

 
Quote:

I found that the Amperex a-frames biased significantly differently from all my other tubes.  You may need to recheck it after installing the Tele's.

Just pulled the cover and checked the bias after an overnight burn-in.  Measured 214mV and 216mV, so in this case things seem alright without re-adjustment.
 
BTW, found a good digital Fluke thermocouple and the internal case temp is ~38C and the surface temp of the top of the warmest heatsink is ~49C.  Ambient temp is currently reading 21C.
 
I like the Telefunken sound so far....
 
BK
 
 

 

[dBel84]

I would be very surprised if the bias went off with a tube change, you may need to balance the tube sections but the output bias should be mostly impervious to tube changes unless the tube was failing..dB

 

[gurubhai]

I never had to change bias on tube rolling.
 
BTW, has anyone else tried the E88CC on the rev. A?
I didn't care for it on my EHHA build but it sounds fantastic on the rev. A.

 

[foet]

How do they sound compared to the - for example - telefunken 6GM8's?
 
I've ordered a matched set of '70 russion military 6N27P for my EHHA rev A to be, and was wondering what would give me a balanced sound with my HE5-LE (that sound quite thin with my current DSP19-C2 combo). My only comparisons would be the standard tubes in the GJA kit if it ever arrives.

Could someneone who has heared the lot could sum it up shortly? I understand tele's are just about as good as you can go 6GM8 wise, but compared to other types there seems to be litle info; especially these russian litle fellas.

 

[stringgz301]

If your headphones sound thin you probably want to go with Tele's (best) or halo getter Amperex (I have some relabeled Seimens like this).  The 6N27P's tend to be more analytical and focused.  I've actually listened to the HE6 through the EHHA-rev A with Tele's and it sounded very nice.

 

[gurubhai]

Quote:

How do they sound compared to the - for example - telefunken 6GM8's?
 

I switched from the tele's last week & haven't felt the urge to revert back.The jury is still out, but on my system the E88CC seems to perform at least as good as, if not better, than the telefunkens.
I had earlier, clearly prefered the teles to Mulllard, Philco,Amperex Bugle Boy,amperex & GE ones.

 

[stringgz301]

Ok Guys.  Need help debugging my balanced EHHA.  All boards start up and bias properly (2 of them are from my original single ended EHHA in operation for months now).  However, I'm getting big hum (constant with a surge about every second).  It is on both sides.  I've disconnected the inputs to the boards (I and IG) and it is still there.  As a first debugging step I found that I have continuity between Out and SG when the boards are powered.  Is this normal?
 
Any debugging suggestions?

 

[jdkJake]

What is the measured value between OUT and Signal Ground?

 

[stringgz301]

OK.  So solved one problem.  Had the rails transformer improperly wired.  Corrected this and started it up again.  Heater and rails power supplies test good, with corrected DC output from heater PS and rails PS.  DC offset 0.  Tubes bias properly.  
 
Have a different hum.  Music plays ok, but when it stops have background hum.  Independent of volume pot.  Could this be the dreaded ground loop?

 

[jdkJake]

OK.  So solved one problem.  Had the rails transformer improperly wired.  Corrected this and started it up again.  Heater and rails power supplies test good, with corrected DC output from heater PS and rails PS.  DC offset 0.  Tubes bias properly.  
 
Have a different hum.  Music plays ok, but when it stops have background hum.  Independent of volume pot.  Could this be the dreaded ground loop?

Maybe. How did you wire it up? Which grounds did you connect to star ground?

 

[funch]

 
I've just started my setup, and am having a problem with the heater supply. I'm using the tranny from the Glassjar kit, an Avel Y236101, 9VAC/1.65A.
I've got it wired with the red/black wires to one board, and the yellow/orange wires to the other. Both boards are reading 13.65VDC at TP3, and the output
is at 12.65VDC. I cannot get the output to change at all. Do I have the tranny wired wrong? Should I pair black/orange and red/yellow? Have I blown the reg's?
I'm stumped.

 

[dwh91307]

I also used the Glassjar kit and experienced same problem with both boards.  I replaced both regs and all is fine now.  Perhaps bad batch of ld1085's.
 
Quote:

 
I've just started my setup, and am having a problem with the heater supply. I'm using the tranny from the Glassjar kit, an Avel Y236101, 9VAC/1.65A.
I've got it wired with the red/black wires to one board, and the yellow/orange wires to the other. Both boards are reading 13.65VDC at TP3, and the output
is at 12.65VDC. I cannot get the output to change at all. Do I have the tranny wired wrong? Should I pair black/orange and red/yellow? Have I blown the reg's?
I'm stumped.

 

 

[stringgz301]

Grounding: right now, each board has 3 sg grounds (I'm using the alternate wiring scheme connection at the front of the board), that all connect to a central terminal.  That ground is isolated from the case (should it be?).  The IEC ground is connected to the case.  
 
A bit of question mark for me is the Khozmo attenuator (4 channel).  It has 4 inputs plus a ground connector, and 1 pair per channel of output and ground connections.  I currently have it wired like the attached (Pic from john mcclean, my annotations, using wire leads instead of his diy bridge between ground connections).  Not sure why he has 2 leads connected to each output ground connection.  Also, not sure why the bridge is required given that on each board the IG connects through the ground plane to SG.
 
 
Any and all help is much appreciated.

 

[sachu]

Quote:

Grounding: right now, each board has 3 sg grounds (I'm using the alternate wiring scheme connection at the front of the board), that all connect to a central terminal.  That ground is isolated from the case (should it be?).  The IEC ground is connected to the case.  
 
Yes. That central terminal needs to be connected through a ground loop breaker to the chassis. Use a 10 ohm/10Watt wirewound resistor with a Class X or Class Y 250VAC capacitor.
 
A bit of question mark for me is the Khozmo attenuator (4 channel).  It has 4 inputs plus a ground connector, and 1 pair per channel of output and ground connections.  I currently have it wired like the attached (Pic from john mcclean, my annotations, using wire leads instead of his diy bridge between ground connections).  Not sure why he has 2 leads connected to each output ground connection.  Also, not sure why the bridge is required given that on each board the IG connects through the ground plane to SG.
 
 
Any and all help is much appreciated.
 
No idea about the multiple leads on the ground pins.. leads to a switch or something else perhaps?