#124 Build Started

Bob S · Post by **Bob S** » Mon Sep 05, 2011 5:17 pm

Thanks to all for the information provided here. Lots of reading.
Lots to learn...
Finally got to work on my #124 - 100W, tubes up build.
Being "upside down" is sending my dyslexia into overdrive.
If anyone sees anything obviously wrong, please let me know.
I'm not keen on the ceramic tube sockets.
I'm not sure whether the Level or Ratio pot is wired through the relay - the schematic and layout I have show it both ways. Or I'm missing something.
Thanks again,
Bob

Structo · Post by **Structo** » Mon Sep 05, 2011 5:59 pm

Cool Bob!

Where did you find the flipped chassis?

If it were me I would probably take the #124 layout and mirror it which you can usually do with photo editing software.

The Ratio pot goes through the OD relay.

The problem is Dumble used several different labels for the OD volume and Gain.

But Ratio on #124 is the OD volume and Level is the OD gain.

Bob S · Post by **Bob S** » Mon Sep 05, 2011 7:05 pm

Thanks Tom - should have thought of flipping the image...
I got the chassis, pre-amp & power string boards & transformers from RJ.
The relay boards & ps board are from Collosal.
Both excellent & great to deal with.

Charles52 · Post by **Charles52** » Mon Sep 05, 2011 8:48 pm

Hi Bob,

Looks great! I assume you'll be building a Marshall type of cabinet. Be aware that your OT is sitting close to the edge of the chassis and be sure it will not conflict with your cabinet.

Happy building,
Charles

David Root · Post by **David Root** » Mon Sep 05, 2011 10:39 pm

Looks good Bob! Nice iron too. I bet that reversed layout Tom posted will really help. Tom, how did you do that? I'm software challenged!

Deric · Post by **Deric** » Mon Sep 05, 2011 11:13 pm

If you wire the pots according to the reversed layout won't they operate backwards? And I'd think the taper of the log pots would reverse also?

Structo · Post by **Structo** » Mon Sep 05, 2011 11:26 pm

Good catch Deric, hadn't thought of that but I haven't reversed a layout before.

Be sure to wire the pots conventionally Bob.

Also I'll be interested in your opinion of the Edcor transformers once you get the amp going.

Bob S · Post by **Bob S** » Mon Sep 05, 2011 11:39 pm

I've got 1/2" (13mm) clearance on the power transformer, so it should be ok. She'll get a hardwood cab when I'm done tinkering with her nether regions.
For the pots I worked from the inputs jacks out.
I'm using the schematic to figure what to where, and the layout for how to get there. I've always mixed up reading/writing b's & d's but this has taken the challenge to a whole new level.
I'll post more pics soon - I'm sure to screw up - again. This is my first D type amp.
Thanks again to RJ & Collosal and everyone here who makes this possible.
You guys are good!

RJ Guitars · Post by **RJ Guitars** » Wed Sep 07, 2011 4:39 pm

Bob,

I am D'Lited to have you taking this project on. I had intentions of making a a #124 clone with everything in exactly the right way and right place... then somewhere in the fab process the sheet metal guy crossed his wires and folded them backwards after the CNC work was done.

Another guy here on the forum has built a couple of these with Edcor transformers... "Fishy" built a pair of them a year or two back. He had great comments on the Edcor sound. It will be nice to have a couple more data points on that too. Edcor is well respected in the HiFi community but a little bit of a new face in the guitar amp world. I send a bunch of them overseas and they seem to be pretty well established over there.

Looking forward to the build progress reports and of course the final results.

rj

ER · Post by ER » Wed Sep 07, 2011 5:15 pm

I'm using Edcor CXPP100-MS-1.7K (OPT), XPWR127-120 (PT), and CXC100-5H-200mA (choke) on my current build (100watt 6ca7). I've been really happy with Edcor stuff in the past. I also like the 12v 500mA tap on the power transformer for switching, and 7.5 amp on the heaters (HV is 345-0-60-345 @ 400mA). 4/8/16 on the OPT and they are all well priced too.

I'm also lysdexic which is why it takes me so long to get stuff done , I draw up my own layouts as sort of a measure twice cut once precaution, and measure all my components before putting them in to be sure. My knobs still go counter clockwise on one of my builds and watch out going from 2nd gen slider switches to 3rd gen toggles.

Luckily 124 is a well documented build, and there are lots of folks willing to share their knowledge if you run into trouble. If you really want to get particular, you may want to turn your OPT 90 degrees like on a dumbleland.

-Erik

markusw · Post by **markusw** » Wed Sep 07, 2011 6:01 pm

Maybe this is of help.
The drawing is not that nice but it works.
Regards,

Markus

Structo · Post by **Structo** » Wed Sep 07, 2011 6:09 pm

I think we need to think about how those pots are going to work when the chassis is sitting there tubes up.

markusw · Post by **markusw** » Wed Sep 07, 2011 7:05 pm

I built the amp like in the layout and the pots work like they should

Peace,

Markus

M Fowler · Post by **M Fowler** » Wed Sep 07, 2011 8:40 pm

One of my projects is a reversed Dumble ODS as well in Marshall style using Edcor trannies PT is 310-0-310/100W and OT 2k1/100w.

It takes some time, but after a while working from flipped layouts. you do get used to it.

Mark

Structo · Post by **Structo** » Wed Sep 07, 2011 8:52 pm

It makes my head hurt thinking about it.

Tube Amp Archive

#124 Build Started

#124 Build Started

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#124 ODS

#124

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Reverse Layout

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