Finished my ST 120 Build

I just finished my ST120 Build.  What a great experience and a great kit.

This amp sounds great. At first i thought it wasnt working it was so quiet. I mean its silent.  Even after the few little changes i did.  I ended up using stranded tefzel wire. I did ground the chasis, also I am not switching the neutral but rather the hot.  Both work but it is safer this way.  I also put an x/y line rated 0.01mfd cap across the switch. Figure it might save the contacts over the years.  I replaced the chinese rectifier tube with a Sovtek. Noticed my bias went up, so i re biased. All in all a beautifull build.  I tried my hand at the lost art of wire lacing with waxed lacing string.  Turns out it takes a bit of practice.  so is stoped. See attached. Also, used one of the unused connections on each of the front sockets to add a chasis ground test point.  This was i avoid risking scratching the chasis with my meter leads when adjusting the bias.

I posted a bunch of photos at this link

http://photobucket.com/mydynaco

Thanks Bob

Mike Mytko
Ontario, Canada

Beautiful build there Mike.
I like the copper paint on the trannies.

Steve

Beautiful!

Yes, thanks for complements. The pictures Bob posted are not yet the finished amp. On the link i posted is the amp with some more wire lacing done to it. I remember working on an old aircraft receiver as a kid and they did a beautifull job with wax lacing string. Needless to say, im not that good at it! I think it is very difficult to wire something neatly that has round sockets as well as the need to maintain certain distance between ac heater wires and signal. As an electrician I am used to wiring large industrial panels were everything is straight, square and either parallel or perpindicular to each other. Wireways called panduct make everything look neat. This amp was a small challenge. Looking at Bobs builds, if you dont care for doing the assembly part yourself, then having Bob Built the amp is worth every penny! For me its all about the build.

Mike

Looks great. I like the way the flat metallic copper paint looks. I think it is so much nicer than a glossy shine.

Hi
Looks like copper but actually a red metalic engine paint. I had to bake the transformer covers in the oven to get it to cure. Stunk up the house a bit!

Very nice job!

Thanks

AM I MISSING SOMETHING? WHY ARE THERE TWO RED WIRE CONNECTIONS BETWEEN THE LEFT AND CENTER DRIVER TUBES? THIS DOES NOT EXIST ON ANY OF MY 3 AMPS. WHAT DO THEY DO THERE?

Hi Bob:
Thanx for the info.
I have an unbuilt octal board with CCS I haven't used yet does it also need that jumper? It didn't mention it in the board build info. Are there any other differences I should know about if I install it in one of my older amps?

it's in the manual but not as obvious as it should be, so I'm revising the manual to make it obvious even if you don't read the instructions,
here is what it says in the old manual . . . .
Filament Power
Attach the filament power - connect the original filament wires (#4&5) to the outer tube and
do the same on the other side with the filament wires (#15&16) to the other outer tube..
You will also need to jumper the filament pins from V2 to V3 (pins 7 & 8 on the 6SN7 tubes).
. . . but . . . the two filament jumpers actually go from V1 to V2

Hi Bob:
I hadn't really gone over the manual in detail because I don't have a spot for that board right now but this was very instructional for me and when I do I owe you one in advance thanks a lot. Good info as usual.

BTW I was wondering why you don't make the holes for the triode/ultralinear mini switches a bit smaller so we don't have to use a washer there and it would also allow the switches to center in the holes.
Geo

Good point.
I found some plastic washers at the hobby shop that act as reducers from 3/8-1/4" and slide over the shaft of the switches and inside the hole that did the job nicely of locating them and I have the switches on one of my amps mounted without the washers. Looks a little tidier. The washers were super cheap. $.40 for 20 of them
I originally tried to use the plastic washers that came with some input jacks. I sanded them slightly to fit and they worked fine when covered up by the nut but I found the others were a better fit without the sanding.
Geo

baddog1946 wrote:BTW I was wondering why you don't make the holes for the triode/ultralinear mini switches a bit smaller so we don't have to use a washer there and it would also allow the switches to center in the holes.
Geo

Thanks for pointing that out
I didn't consider it when planning the upgrades for my MK-II's.