High Plate Skyline 100 Watt ODS

[Structo]

The crackling was a preamp tube. Don't know which one cause I replaced all of them.


The relays are OD, PAB, Mid Boost and Bright on clean only.

It seems to be working right now. I need to do some fine tuning.

I'm surprised at the power tube plate voltage, at only 433v?

I thought these Twin transformers were up around 450-460v?

Also, I swear the mini switches on the front panel are working backwards.
I have Bright, Deep and Rock/Jazz.

The Deep and Rock/ Jazz seem to be not working correctly.

I figure Rock is supposed to be brighter and louder right?

Pretty sure I have them wired right. I'll have to dig into that later.
Got to run up to the parts store and get some foot pedal cable and another relay.

[Deric]

Looking good Tom

[Structo]

Thanks Deric.

Man, I can't believe how loud this sucker is.

I mean, I play the 50 watt through the Dumbleator so I throttle it with that but man, this 100 watt is like vibrating crap off the shelves at 9:00-10:00 on the volume and master.

Question for those of you with the Rock/Jazz switch.

When I flip mine to Rock, it adds a lot of bass and volume, is that normal?

I have this Brown Note Deluxe layout and it shows the switches wired backwards from what #124 shows.
I suspect #124 is the right way or we would have fixed it, right?

I wired the panel Mid Boost switch as a Deep switch.
Not sure I like it and may revert back to Mid Boost.

[Structo]

5A might be a bit close

6L6 draw 900mA each, and you got 4. That alone is pretty close to 5A, then add in pre amp tubes.

Is this a new type of math

0.9A * 4 is 3.6A. Fairly close to 5. Add in the preamp tubes for another 0.9A. 4.5A total, too close for me.

I don't know math too well though. I'm an electrical engineering student, no math there.

Chris, not sure what you are saying 4.5 A is too close to?

The wire I am using is rated at 10 amps.

[Bob-I]

Thanks Deric.

Man, I can't believe how loud this sucker is.

I mean, I play the 50 watt through the Dumbleator so I throttle it with that but man, this 100 watt is like vibrating crap off the shelves at 9:00-10:00 on the volume and master.

Damn straight. I really can't use my 100 watter in any situation right now, it's just too loud. Sounds amazing but damn it's loud.

Question for those of you with the Rock/Jazz switch.

When I flip mine to Rock, it adds a lot of bass and volume, is that normal?

Sounds normal to me. In jazz mode if you tweak the tones, adding bass especially you'll get that classic mellow jazz tone on the neck PU. Without adjusting anything you're change sounds normal.

I wired the panel Mid Boost switch as a Deep switch.
Not sure I like it and may revert back to Mid Boost.

I agree. I'm adding a relay for my mid boost as well, really useful for pushing leads out front in the mix.

[Bob-I]

Oh... and about 45 seconds in he flips the jazz / rock switch. You'll hear it.

http://www.youtube.com/watch?v=ap6odoC4itw

[Structo]

Thanks Bob, I forgot that Peter uses the switches in that video.

Mine has a bigger difference when I switch the Rock switch, but it might be because of where the other knobs are set at.

There is something going on with the voltages I'm having trouble figuring out.

I measured all voltages and made a chart.

Power tube plate voltage a bit low but so is the wall voltage at 119v.
It's usually around 120-122 vac here.

There is a 42 volt difference between the plates of V1 and 50 volts difference on V2.

I've changed V1 & V2 about four times with little improvement on the spread.

On my D'lite there is a 6v difference on V1 and a 9v difference on V2.

Both amps are high plate (220K and 150K) with the coinciding cathode resistors, 3K3 and 2K2.

I changed the 22K dropping resistor to from 22K to 30K to lower V1 and V2 voltages.
So the string is 2K2, 30K and 2K2.

My preamp tubes are oriented like #124, with the second triode as first stage.

[Bob-I]

Mine has a bigger difference when I switch the Rock switch, but it might be because of where the other knobs are set at.

Simple, look at his settings then remember that Dumble oftne used 30% pots and make some adjustments. I find my J/R switch reacts very much like Peters.... If only I could play like Peter

There is something going on with the voltages I'm having trouble figuring out.

I measured all voltages and made a chart.

Power tube plate voltage a bit low but so is the wall voltage at 119v.
It's usually around 120-122 vac here.

There is a 42 volt difference between the plates of V1 and 50 volts difference on V2.

I've changed V1 & V2 about four times with little improvement on the spread.

On my D'lite there is a 6v difference on V1 and a 9v difference on V2.

Both amps are high plate (220K and 150K) with the coinciding cathode resistors, 3K3 and 2K2.

I changed the 22K dropping resistor to from 22K to 30K to lower V1 and V2 voltages.
So the string is 2K2, 30K and 2K2.

My preamp tubes are oriented like #124, with the second triode as first stage.

The triode on pins 6-7-8 IS the first triode. The 12AX7 was designed to have this the first gain stage, 1-2-3 as the second. It DOES make a difference in the noise floor.

Your plate voltage isn't really all that off for this iron, but the V1/V2 problem is an issue. You cathode readings are low as well. I'd double check the resistor values on Rp and Rk, something's wrong.

[Structo]

CRAP!

That's what I did alright.

I have the cathode leads backwards.

I have the 3K3 going to the 150K side and the 2K2 going to the 220K side.

Right now the simplest fix looks like just pulling the resistors and swapping them.
Otherwise I'll have to pull the board to change the wiring, because as it is, the wires are too short to go where they need to go.

Thanks a lot Bob, it sure is easy to miss the obvious.

[Bob-I]

CRAP!

That's what I did alright.

I have the cathode leads backwards.

I have the 3K3 going to the 150K side and the 2K2 going to the 220K side.

Right now the simplest fix looks like just pulling the resistors and swapping them.
Otherwise I'll have to pull the board to change the wiring, because as it is, the wires are too short to go where they need to go.

Thanks a lot Bob, it sure is easy to miss the obvious.

Been there. The cathode wire closest to the tube will be easy, the one by the pots is harder but you won't have to pull the board. Solder a new wire to the existing one and pull it under the board. After a lot of struggling and cursing you'll get it through.

[Structo]

Working on it.

I'm snaking new leads through.

I wonder how many other bone head mistakes I've made?

[erwin_ve]

Hi Tom,

That's looking good! Impressive wiring with 4 relays. How's your heart doing with this exciting project?

Erwin

[Structo]

Thanks Erwin,

My heart is doing well. I was fortunate in that it didn't suffer any damage.

Yeah the relays, I couldn't fit the PAB relay under the switches. For some reason it was too tall.
So stacking two worked out.

Voltages are much better now with the cathodes resistors sorted out.

I reinstalled the 22K dropper and measured these voltages.

I also took out the Deep switch and changed it to Mid Boost.

I wish I hadn't because I think the wrong cathode resistors was really messing with the tone.

Edit:
I might add that the power tubes I have in this amp are two SED Winged C 6L6GC and two JJ 6L6GC.
I have dual bias pots so I can balance the two sides but I really need to get a matched quad for this amp.
I will as soon as the budget allows....

What's everybody's current favorite new 6L6GC?

[ToneMerc]

Great job Tom!

Mike

[Structo]

Thanks Mike,

My assembly skill isn't as good as a lot of amps here but it works.

How many of you like your amp in the Rock position?

Mine seems too dark and bassy in Rock.

I changed the .005uF cap to a .001uF on the switch and it still is a bit much.

Maybe that works well with single coils but with my humbucker guitar I don't really care for it.

I'm having some difficulty in tweaking the amp to work with the Dumbleator.

Way different than my D'lite. Kind hard to dial in clean tone without distortion unless I have it pretty loud.