Another 100W Low-Plate Skyliner

[CHIP]

Thanks Martin,
that's how I'm going to wire my bright switch.
Again, your build is inspirational.

[Structo]

Thanks again Tom, my face is red! To be sure, this kind of thing is over the top... I'd starve if I were selling them, and I'm sure the pro's here know that!

I know what you mean, there is a tremendous amount of labor on these amps.

Oh yeah, I know what I was going ask you.
On the power tube plates, is the wire from where the OT wire is soldered to pin 3 on the left tube then ran to the right tube just laying on top of the socket then terminated on pin 3 of the right tube?
The extra blue and brown wires?

That probably is about clear as mud.....

MC iron?

How about a picture of the control pots?

[martin manning]

On the power tube plates, is the wire from where the OT wire is soldered to pin 3 on the left tube then ran to the right tube just laying on top of the socket then terminated on pin 3 of the right tube? The extra blue and brown wires? MC iron?

Re the power tube wiring, you've got it. The plate leads are in the upper holes of the tube socket lugs, though, so they are above the sockets a bit. The screens are in the lower holes since the screen resistors need the upper ones.
The PT is a Hammond 290FX and the OT is a Heyboer Twin Reverb replacement (with 4-8-16 taps) from Mojo. Interesting story there... The documentation that came with the OT was in error; the 8 and 4 ohm colors were switched on the schematic (drawn by Mojo, not Heyboer). I found this when I tested it for primary-secondary phasing, which was correct, but not shown on the drawing.

How about a picture of the control pots?

Alright... Back panel too?

[wjdunham]

Stunning build Martin, looks as good as any build we've seen here. What type of wire are you using, teflon coated, gauge? Looks very authentic.
Thanks,
Bill

[ChrisM]

Looks great Martin!

Whats with the resistor on the presence pot?

[martin manning]

Stunning build Martin, looks as good as any build we've seen here. What type of wire are you using, teflon coated, gauge?

Thanks! The hookup wire is 22ga 7/30 pre-bonded with 600V PVC insulation. It has some spring-back, but routes almost like solid. The coax is 50-Ohm RG-174, silver with PTFE covering; 0.100" O.D.

Looks great Martin! What's with the resistor on the presence pot?

Thanks, Chris, that's a 5k pot masquerading as a 2k (3k3 shunt).

[wjdunham]

Thanks! The hookup wire is 22ga 7/30 pre-bonded with 600V PVC insulation. It has some spring-back, but routes almost like solid. The coax is 50-Ohm RG-174, silver with PTFE covering; 0.100" O.D.

Would this be very similar/same as what you are using?
http://www.mcmaster.com/#electrical-wir ... ds/=a38yjf
Thanks,
Bill

[Structo]

Martin, are the blue film resistors you used Vishay BC?

Also, what did you do on the OD entrance, there before the trimmer you have a resistor going to ground.
What does that do?

[mad_dog]

That is one very impressive build.

Thanks for the great pics as well, I always love to see other peoples work, especially when it is this clean

[martin manning]

Thanks! The hookup wire is 22ga 7/30 pre-bonded with 600V PVC insulation. It has some spring-back, but routes almost like solid. The coax is 50-Ohm RG-174, silver with PTFE covering; 0.100" O.D.

Would this be very similar/same as what you are using?
http://www.mcmaster.com/#electrical-wir ... ds/=a38yjf

Bill, that link doesn't go to a specific product, but I worked my way down and didn't find any pre bonded wire there. I got it from MetroAmp, but he doesn't sell it anymore. I've e-mailed to see if I can get/find more, and will post if I have any luck.

Martin, are the blue film resistors you used Vishay BC? Also, what did you do on the OD entrance, there before the trimmer you have a resistor going to ground.
What does that do?

All the resistors are Xicon. The one at the bottom of the OD entrance trimmer is mostly just completing the ground connection right now ( its 4k7). Doing it that way makes it easy to experiment with changing the total resistance to ground. I saw this on Gil's last amp, and figured why not?

That is one very impressive build. Thanks for the great pics as well, I always love to see other peoples work, especially when it is this clean.

Thank you, and you are most welcome.

[martin manning]

A small update: I heard back from my query to MetroAmp about the wire they used to sell... It's no longer available through them as they are now out of the parts business altogether.

[telentubes]

One of the cleanest amp builds I've seen to date. Congratulations! Some version of a Dumble is next up for me and my work bench, and your amp is certainly an inspiration. I'm in "research mode" for now, trying to zero in on which version to tackle, so look forward to more info and impressions of this project of yours. Again, beautiful work!!!

[gary sanders]

Are you liking the micas for the bright switch?I was going to do that but heard a few say they didnt like them for brights.

[Structo]

I'm using polystyrene right now.

They are much more subtle than ceramic or mica.
Smoother.
But, I'm thinking I may prefer ceramic in the bright cap situation.

But like for a treble or other small cap the polystyrene might be the answer.

[martin manning]

Thanks, Telentubes! One thing I learned along the way here is just pick a baseline to start from and build it to that spec throughout. I think the only decision that would be lot of work to reverse is HRM or not.

One of the guys who teaches at the local music store works with one of the companies that is making D-clones. I took this amp over to have him play it and comment last week, and he ran it through all the modes and settings (lucky me, huh?). I specifically asked about the highs wrt the bright switch and the possible addition of a treble bleed, and he said he wouldn't change a thing :^)

I like the sound of the micas on the bright switch, and the dual setting, but I didn't A/B them with anything else. I think I recall reading that some Dumbles did have micas there too.

I plan on experimenting with a treble bleed to see what it does to the character of the OD, and also with disabling the LNFB on V1. No time right now, though. Still hoping to get some clips up too.