New build complete: CE Silverface 6V6 HRM

[ToneMerc]

Almost done here......whew. I did manage to screw up the buss bar though, I snipped off the wrong end leaving it short. Since I already had the tags and components soldered to it, I just extended it with a jumper.

TM

[Dr d]

As usual, your build looks immaculate! Thanks for sharing.

[ToneMerc]

Moment of truth or smoke!

Loaded it wth TS RI 6V6's, JJ83's in V1& V2 and a balanced LPS in V3.

Pri: 124.8V , highest I've recorded since I've been here.

Heater: 6.22V @V1

Bias string: 750>10K>16K

B+ string: 600>16K>1.6K

V1: 173/178
V2: 179/183
V3: 274/280

Looks like I need to drop that 600 to increase everything about 8-10V and then maybe increase the 1.6K a bit.


Plates: 402
Screens: 400

Bias: 21-22 range

FET:2N4416A, 21/10


TM

[talbany]

Mike
What is the power rating on that X-former?
Dropping the 600 ohm might give you a couple volts or so (a 1k on the screens at idle drops what 2 volts) I wouldn't bother... 280v is still Ok for the Pi..IMO...If you wanted to search through a few 83's and see if you can get that up a few volts but I think that's pretty much all your going to get out of it..I would try a 10k in place of the 16 that might get you in the lower 190 range on V2...You might have to go lower..

August is the worst month for me with voltage swings too!!

Tony

[ToneMerc]

Mike
What is the power rating on that X-former?
Dropping the 600 ohm might give you a couple volts or so I wouldn't bother... 280v is still Ok for the Pi..IMO...If you wanted to search through a few 83's and see if you can get that up a few volts but I think that's pretty much all your going to get out of it..I would try a 10k in place of the 16 that might get you in the lower 190 range..

August is the worst month for me with voltage swings too!!

Tony

Pri: 122
Sec: 295-0-45-295 @ 400mA
6.3V @ 500mA
6.3V @ 5.5.A

The darn thing weighs almost 14 pounds and I swear the lam stack is taller than the 307V units I ordered in the past. I was actually expecting the PI to be slightly higher. I think I have a 11K, I'll give it a try.

thanks


M

[boldaslove6789]

Those JJ83's have lowered plate voltage before for me, as well as some NOS Ge short plates (made B+ drop 10-20v) from what I had documented with a EH or Sovtek 12ax7 .

I've had plate B+ of at least 190-195 (+or- 5v pending on what tubes i was using) on V2a/b on HRM's, never got it as low as 180, but from tube to tube its acceptable (If it sounds good ).

Me and Jim Price (Groovtubin) were just talking about this the other day.

Darn HRM's are so finicky but plate B+ is soo key.

Anybody have the plate & B+ node measurements from a real "standard grail era" Skyline HRM Dumble?

Hope the amp sounds Great for ya!

[ToneMerc]

Couldn't find that 11K, but I did have a 9.1K.Not sure if I'm going to leave the 9.1K though. The RCA NOS I tried as well read about 8-10V higher.

Also, reversed the OT primaries which fixed the intermittent OT chirp and the wild varying bias readings.

B+ string: 600>9.1K>1.6K

V1: 188/194
V2: 196/201
V3: 279/271

Plates: 393
Screens: 391

These plates/screens voltages are more in line of what I was expecting from the 295V PT as I had predicted about 390V with a quad of 6V6's.

Tomorrow, i'll pump a signal pumped through it for a few hours and then scope balance the PI.

TM

[ToneMerc]

Those JJ83's have lower plate voltage before for me

Greg, same here I typically see about a 10V delta when using the JJ83 over many NOS tubes. Thats why I try to find a compromise in the string values sometimes, knowing NOS glass might be be available.

thanks

Mike

[ToneMerc]

Finally done playing musical JJ83's in V1&V2.

Pri: 123.3V

B+ string: 600>13K>1.6K

V1: 183/185
V2: 198/199
V3: 285/280

Plates: 400
Screens: 398

TM

[aflynt]

Very beautiful job, ToneMerc! Those big Pihers are making me jealous. I used a bunch in my build and the sound great, but they sure weren't easy to find in the right values and higher wattages.

-Aaron

[Structo]

Nice!

Another great build from Tonemerc.

[M Fowler]

Very nice build.

I haven't found any Pihers resistors either the quantity available must be drying up.

[dcribbs1412]

Congrats TM...
Exquisite build...(new amp adjective?...)
Amp builds are becoming works of art around here lately...
Any comments on the Brown Drops yet?

Darin

[ToneMerc]

Very beautiful job, ToneMerc! Those big Pihers are making me jealous. I used a bunch in my build and the sound great, but they sure weren't easy to find in the right values and higher wattages.

-Aaron

Thanks man. Those ones on the power tube grids are the rarest of Pihers. I have a hunch Piher didn't actual make them and they just rebranded. I've only seen a couple of that type in actual Dumble build pics.

I received them in the first Pihers that I ever purchased, about 4 years ago. I guy had what appeared to be about 2-4 pounds of NOS resistors dumped on his kitchen table. A fair bit of the lot was CC stuff mainly AB and some Morganite, but could tell they were some Pihers amongst them, just not to sure of values. When you looked at it from the surface, the pile looked like junk because of the way it was presented and that's how everyone else saw it. I took a gamble and it actually turned out well. Pihers were never mentioned in the ad, the lot was simply listed as NOS resistors. The lesson, don't all the time look for the obvious because everyone is competing for the obvious.

I hadn't planned on using the 1W in the OD entrance. Normally the circuit calls for a 470K and 200K, but all my .5W values(470, 180, 220) were relatively spot on. However, I did find 1W 470K and 180K values that actually read 478K and 192K. The lesson, never discount any value, as all values can be important.

TM

[ToneMerc]

Very nice build.

I haven't found any Pihers resistors either the quantity available must be drying up.

Actually, in the last year you can trip over them. I can remember when couldn't even find them on eBay.

TM