[balderon]

Quote:

Originally Posted by regal /img/forum/go_quote.gif I had no hum with HD650's, do you have a picture of the amp's insides?

This exercise in adapting to a regulated DC heater circuit has uncovered an issue with my heater wiring. The left channel 6DJ8 had the heater wiring reversed. I don't know if the phase difference contributed to the slight hum I was experiencing on that same channel.

One thing for certain is I disconnected the all heater wires in preparation of installing the regulated DC circuit. This forced me to examine all heater connections. I cut off the ends of the wires and made fresh connections. Perhaps I had bad connection as well. In any case the slight hum I was experiencing has disappeared and has not returned even when moving the wires while listening with the amp power.

I will post pics after I secure the wiring and reinstall some add-on components that were not a source of the hum.

 

[fishski13]

Quote:

Originally Posted by Ant1Xr1st /img/forum/go_quote.gif I have hear such heater voltage difference with soviet 6N1P and 6S45P tubes.

i've also read that some people prefer a lower heater voltage at around 6.0V. i wonder if these preferences could be attributed by how a tube in situ is biased wrt the load-line and the transconductance of that tube. btw, i've never compared differences.

 

[balderon]

Quote:

Originally Posted by fishski13 /img/forum/go_quote.gif sorry, i haven't searched, but do you have schematic and how much current are the heaters using up for your tubes?

6DJ8 : 2 x 0.365A = 0.73A
JJ ECC99 : 2 x 0.8A = 1.6A

The circuit I was planning to use is Pete Millett Regulated DC filament supply circuit. As I no longer have a need for this circuit the unused parts with the exception of a heat sink and choke are available for sale. At cost of course.

 

[fishski13]

Quote:

Originally Posted by balderon /img/forum/go_quote.gif 6DJ8 : 2 x 0.365A = 0.73A JJ ECC99 : 2 x 0.8A = 1.6A The circuit I was planning to use is Pete Millett Regulated DC filament supply circuit. As I no longer have a need for this circuit the unused parts with the exception of a heat sink and choke are available for sale. At cost of course.

do you have a part number for the choke? i might be interested.

 

[balderon]

Quote:

Originally Posted by fishski13 /img/forum/go_quote.gif do you have a part number for the choke? i might be interested.

Sorry, I do not nor did I did try searching for it.

EDIT: I took a few moments and figured out what the part number / specs for the choke. Unfortunately it is now an obsolete part. Pulse Engineering PE-96173

 

[dean0]

Update;

- Bugle Boy 6DJ8 Valves
- EZ81 P/S
- Regal Mods
- 100k Stepped Attenuator

 

[funch]

Very nice, dean0. Any pics with the top on?

 

[balderon]

Nice build Dean0! Did you resolve the height problem with the EZ81?

 

[dean0]

Quote:

Originally Posted by balderon /img/forum/go_quote.gif Nice build Dean0! Did you resolve the height problem with the EZ81?

No not yet, just been running without the top. Iam thinking about mounting it sideways internaly, off the pcb with a shield, would this cause any problems?
thanks

 

[adamus]

shouldnt cause an issue if you can fit it.

other option is to cut a hole in the top.

 

[dean0]

Quote:

Originally Posted by adamus /img/forum/go_quote.gif shouldnt cause an issue if you can fit it. other option is to cut a hole in the top.

I would cut a hole but the position it is in would look wrong (vented area), and the other holes are cnc cut...

 

[trv]

Finished building Bijou last night.
I have to say it sounds mighty impressive right from the start.
No hums, buzzes etc. Wow. I´m happy

Will do Regal mod after break in, and will change the tubes for Telefunken or Mullards that i use in all my valveamps

I use Sennheiser 650 headphones only, so i did leave out the NFB

 

[rolotube]

Quote:

Originally Posted by regal /img/forum/go_quote.gif For regulated DC source a 50VA dual secondary 9V transformer and build a separate regulator/circuit for the Ecc99 & 6n1p. Use the Lm1085 regulators with case mounted heatinks, also elevate the DC with a divider from the powersupply. A lot of money and time. IMO DC heating is unnecessary for this amp, this in truly an amp for high ohm phones where you will never hear heater hum. The SOHAII is a much better choice for Grados and the like.

I agree with regal's comments re hum. I'm using amphead's mods (100R resistors across heater supply with CT to earth) & no DC float off HV line. Absolutely dead quiet. IMO, careful attention to layout & quality wire will go a long way towards achieving a silent amp. I have considered DC heaters but doubt the improvements, actual or perceived, would be detectable.

The SOHA II may be better for other phones but mine works superbly with my HD650's, although I'd have to say, not quite in the same class as the Bijou.

 

[rolotube]

Quote:

Originally Posted by GWorlDofSPACE /img/forum/go_quote.gif Do I really need to measure the voltage at the input to the phase splitter? How to do this? I have found a good source for Mcaps and want to know if somebody has tried M-tubecaps. There are 100-200uF available from the source?

I'm using Tubecaps throughout. In the PS, C1 (200uF), C4, 5, 6 (47uF) with choke mods. In the amp, I'm running a 200uF as the output cap, no bypass. Results are excellent, much better than stock electros. Others have used 330uF Mundorf MKP on the output. This may well be a better solution than the Tubecap, but is twice the price.

 

[S3TUP]

Hi! I'm building the Bijou right now and got a question:

I use a toroidal transformer from Antek-inc, and it has double 6.3v rails 3.5a each.
Should i take one winding for PSU and other one for amps, or that doesn't matters much as it's just a heater supply?


It's going to be all-russian tube Биджо(russian Bijou

) (6n1p + 6n6p for now, with 6n23p instead of 6n1p in near future).
+ ladder attuneator
+ arduino micro controller
+ nixie volume display.