70's 100 Watt Hybid Started

[dcribbs1412]

Looks great steve
glad to hear its sounding good.
I noticed you used resistors for the heater tap instead of the transformer center tap.
What cab/speaker(s) you have?
Again nice job.

Darin

[steve_p]

Hi Darrin,
I did use 121 Ohm - 1% resistors to ground reference the center tap.
I was going back and forth for awhile, but my take from reading some respected builders posts here is that the resistors are the way to go.

I have 2 cabs to chose from, a single 12 with an EV 12L and a 2x12 loaded with Heritage G12-65Hs.
Both cabs were made my TAG member Super100. Highly recomended.

I just hapened to have a 22k - 3W resistor left over from my z-wreck build awhile back, so I subbed that in and my voltages came up a bit.

I didn't chart them all this time, but i believe my V1 Plates were about 190 and my V2 plates were about 198. I am not going to mess with it anymore at the moment.

Got the chassis loaded into the cab...now I need to start playing alot.

Oh yea, and I need to build my mini-dumbleator (ala Martin Mannings layout).

[dcribbs1412]

Last pic looks like a really nice match
congrats...Whats next...102 maybe

Darin

[steve_p]

Last pic looks like a really nice match
congrats...Whats next...102 maybe

Darin

Not sure...I have a 124 that was my 1st and only other d-build. I haven't done a high plate amp yet, or one with el34s.... 183 may be in the cards next. But, I would be interested to try a 102 also...that has the high plate loads too...and the soft filtering.
I may just need to build both. Man this is an addictive hobby.

[steve_p]

Hmmm...
So I was playing the amp today when the fuse blew.
I only had a 3A fuse in there, so that may have been slightly under rated.
I will pick up some 5A fuses for replacment.

However, it appears that one of my power tubes is not working correctly.
I can not see the filament glowing in 1 tube, and I am not reading any voltage across the 1ohm bias resistor for that tube. The problem travels with the tube when I switch positions.
All others seem fine.
I will admit that when I fired up and checked my bias reading, I only checked 2 of the 4 tubes, so this problem may have been there from the start. I can not be certain.

Tubes are Tung Sol 6l6GC-STR Reissue tubes.

I put an email into CE to see if they will replace the tube or the set.

[steve_p]

Minor update:
Popped in another set of tubes and checked voltages, everything looks fine.

Could have just been infant mortality on that tube.

Strange.

[ToneMerc]

Hmmm...
So I was playing the amp today when the fuse blew.
I only had a 3A fuse in there, so that may have been slightly under rated.
I will pick up some 5A fuses for replacment.

However, it appears that one of my power tubes is not working correctly.
I can not see the filament glowing in 1 tube, and I am not reading any voltage across the 1ohm bias resistor for that tube. The problem travels with the tube when I switch positions.
All others seem fine.
I will admit that when I fired up and checked my bias reading, I only checked 2 of the 4 tubes, so this problem may have been there from the start. I can not be certain.

Tubes are Tung Sol 6l6GC-STR Reissue tubes.

I put an email into CE to see if they will replace the tube or the set.

looks great, a 3A slow blow is all you need.

TM

[steve_p]

Thanks tm.
I looked at pictures i took last night and it definitely looks like all four filaments were lit.
I wonder if that tube crapping out was what took out the fuse.
I couldn't find anything wrong inside the chassis.

Oh well, I'll have to keep an eye on it.

[ToneMerc]

Thanks tm.
I looked at pictures i took last night and it definitely looks like all four filaments were lit.
I wonder if that tube crapping out was what took out the fuse.

Good possibility

TM