Another 100W Low-Plate Skyliner

[martin manning]

Slow in coming, but definitely worth the wait. Thanks to the forum for supplying the knowledge and sources of supply, mdroberts and odourboy for the chassis, jborders5 for the boards, and a special thanks to the Ayan Gil school of lead dress. Powered up first time with everything fully functional and no hum or oscillations.

Sounds pretty good really, but there is a little tweaking left: only 175V on V1 plates (424V B+1 from a Hammond 290FX PT... 3k3 first dropping resistor needs to be ~1k8, I think...), maybe add a treble bleed, and then there will be the usual (and probably endless) experimentation with various component values. Oh yea, and she needs to put some clothes on before going out!

[bigmik]

dam nice build ,when my amp was in it's 100k incarnation I liked the pre amp voltages on the low side ,super clean work anyhow.

[Structo]

Very nice and tidy construction Martin.

An amp to be proud of.

How are you liking the overdrive?

My voltages were a bit low.
I used the old style power supply but my first dropper
wound up being a 1K. 433v B+

[Bob-I]

Nice clean work. Forget the clothes, just cover her with a plexi shield and show her off, nekid!

[jborders5]

Looks great! This is the first complete build I've seen with the boards.

[glasman]

Very pretty work!!

[ayan]

Slow in coming, but definitely worth the wait. Thanks to the forum for supplying the knowledge and sources of supply, mdroberts and odourboy for the chassis, jborders5 for the boards, and a special thanks to the Ayan Gil school of lead dress. Powered up first time with everything fully functional and no hum or oscillations.

Sounds pretty good really, but there is a little tweaking left: only 175V on V1 plates (424V B+1 from a Hammond 290FX PT... 3k3 first dropping resistor needs to be ~1k8, I think...), maybe add a treble bleed, and then there will be the usual (and probably endless) experimentation with various component values. Oh yea, and she needs to put some clothes on before going out!

When an amp looks that good, it matters not what it sounds like. Congratulations, Martin!

Gil

[gilgalad101]

I was wondering how those boards look in a completed amp. Nice job!

[martin manning]

Thanks very much for the kind words. I like nekid, er, inner beauty, yea, that's it. Gary, can you see the LNFB on V1b? The junction of the two 22-Meg resistors is right next to the ground lug on that rear terminal strip... ready for an on/off switch if desired. Your suggestion from a while back; thanks. Gil, I had a print of your photo of your "last amp" as a guide, and referred to it often. Mine seems to have no stability problems, and so with the right tubes, and maybe some tweaking, I'm hoping that there is a way to get it to sound as good as it looks. Thanks to you and others for posting all the details related to tuning... I've saved many of them, and will no doubt have some fun with that. Tom, the overdrive is great. I have to play with the entrance trimmer and see how to balance that with the full-on drive distortion level. Oh, and I forgot to give icracer props for the great #124 schematic and the others he drew up.

A couple of other details:

There are dual mica bright caps, 100p and 300p. This gives an option for somewhat subtle or a little more in-your-face... I like that feature a lot.

The FET is a metal can 2N4416A, and I ended up using 150k/22k voltage divider to get the Vcc, and a 2.0k source resistor to get Vd = ~Vcc/2. Should be as good or better than the NTE part.

The front panel LED (blue, of course!) runs from the 12V relay supply, with a 2k2 current limiter to keep the brightness down a bit. This helped to clean up the area around the power tubes, and I understand that the LM7812 is happier with that continuous current draw when the relays are both out, too.

[TheHandsomeOrk]

Clean as a whistle and pretty.

[CHIP]

Very nice build!

[ToneMerc]

Sweet build, very clean!

TM

[M Fowler]

Great looking build Martin.

[tubedogsmith]

Great looking build!!!

[daydreamer]

wow, that is sharp. It looks like a color layout diagram! everything straight, symmetrical. Minus the cat and better lighting and I would have thought it was done on a computer...fantastic.