First Generation ODS #004 Just Wired Up

[David Root]

Just finished this afternoon, clean is nice, relays not working yet, I used a new FSW, have to check its wiring (and mine too). I have to tweak the FET bias too, it's way off spec.

Edit: relay issues all fixed, see page 2.

Voltages are a tad high vs. the (schematic) at B+1 457 (445), B+2 457 (444), B+3 426 (412), B+4 281 (273), and B+5 253 (245).

Tried out a just received pair of NOS Tung-Sol 6L6GC, but RCA blackplates sound better to me after I changed over to the RCAs. Put a long plate Amperex in V1, a short plate Mullard in V2 and a Funkin ridged plate in the PI. I think I will try a .01uF in the PI entrance, it's not overly bassy, could be a bit warmer, even with the RCA blackplates. I have a .005 there now.

The chassis is from Bob at rjguitars.net, 17x8x2, 1/8" aluminum and I had to drill/cut every hole in it, what a chore. I figured the first gen amps' chassis are the same size as the Overdrive Deluxe. I scaled the pic of David Lindley's two which I think are 002 and 008, could be wrong on that, and the numbers I got match 17x8x2.

I have a nice blue suede head cab with Vox grillecloth that Taylor Cox made special for me. Once I get this build shaken out I'm going to do a Dumbleator in the same size chassis as I'm not crazy about 19" 1U racks.

I used the 2nd Gen Funky OD entrance as everyone thinks the one in the hand drawn schematic is not correct. Other than that it's per the schematic, with the addition of separate MVs for clean and OD and toggle switches instead of slide switches. Oh, and an unbuffered loop instead of only preamp out.

Practically all NOS parts except the OT which is a used '64 Bassman. Except the relays and relay PS, thanx Dave (Colossal here on TAG).

[aflynt]

Woah! Nice job! That first pic is giving me Piher envy.

-Aaron

[David Root]

Pihers were made in Spain, on the Costa Lotta!

I have to order faceplate and backplate for it tomorrow, so it won't be going in its cab for about three weeks or so.

The power supply is all 600V caps, so I didn't need to series two caps for the plate supply. Saves space in this smaller than normal chassis. Original first gens had the PS caps in a doghouse on top of the chassis, Fender style, I'm told.

[aflynt]

Pihers were made in Spain, on the Costa Lotta!

-Aaron

[ToneMerc]

David, excellent choice in resistors and brown turds...lol

TM

[David Root]

Thanx TM, I prefer to think of the signal caps as chocodrops, it's less disturbing at mealtimes! Those CDEs are like hen's teeth, especially the .1uF 400/600V, they are damn near unobtainium, I had to sub El Menco-Arco in a couple of spots.

The resistors are the best, Mepco-Electra, Piher and the odd Draloric and Iskra carbon film too, to fill out values I can't get in Piher. Too bad there don't seem to be any more of the older Electra 100K metal films out there, at least I have been unable to find any. I have lots of Electras in the other values, was lucky to find them.

I looked yours over before I started on mine for any ideas. No point in reinventing the wheel, after all.

I found it difficult as I had to build it from a hand drawn schematic supplemented by three 2nd gen layouts. I was pleasantly surprised that the main board looked a lot like a second gen board in the end.

Keeping the first gen layout of the FET and PS/Bias rectifier board off the chassis walls ate up a fair amount of space so it's good that I didn't try to put in a buffered loop. The two MVs took up extra space on the front of the chassis but that was worth doing I think.

I had to change the bias supply 3K3 entrance to 1K5 in order to get the bias negative enough to get 33-34mA cathode draw, -53.5V. With the 3K3 in there I could not quite get down to -50V.

The FET board is going to take some time to bias properly. The layout is a bit different and the 2N3823 seems to be a bit lower gain than a 2N4416. I was lucky to find a couple of 2N3823 on Ebay for less than the NTE452. I left out the extra 68K bypassed with a switch to the input as I couldn't for the life of me figure out its purpose.

Do you think my using a single 40uF 600V plate cap instead of a series 2x80uF 350V will make a difference in tone and/or feel?

[ToneMerc]

Thanx TM, I prefer to think of the signal caps as chocodrops, it's less disturbing at mealtimes! Those CDEs are like hen's teeth, especially the .1uF 400/600V, they are damn near unobtainium, I had to sub El Menco-Arco in a couple of spots.

The resistors are the best, Mepco-Electra, Piher and the odd Draloric and Iskra carbon film too, to fill out values I can't get in Piher. Too bad there don't seem to be any more of the older Electra 100K metal films out there, at least I have been unable to find any. I have lots of Electras in the other values, was lucky to find them.

I looked yours over before I started on mine for any ideas. No point in reinventing the wheel, after all.

I found it difficult as I had to build it from a hand drawn schematic supplemented by three 2nd gen layouts. I was pleasantly surprised that the main board looked a lot like a second gen board in the end.

Keeping the first gen layout of the FET and PS/Bias rectifier board off the chassis walls ate up a fair amount of space so it's good that I didn't try to put in a buffered loop. The two MVs took up extra space on the front of the chassis but that was worth doing I think.

The FET board is going to take some time to bias properly. The layout is a bit different and the 2N3823 seems to be a bit lower gain than a 2N4416. I was lucky to find a couple of 2N3823 on Ebay for less than the NTE452.

Do you think my using a single 40uF 600V plate cap instead of a series 2x80uF 350V will make a difference in tone and/or feel?

I had enough CDE .1, but decided to not to use up my last two at the time in this build and used the EM as well. Man, you should have asked, I would have sent you a couple of 2N3823's. I think they are nosier that the 4416 though.

I think you will be fine with the single cap, I did drop the B4&B5 filtering on mine slightly, it's 16uf. Maybe one day I will experiment with 10uf there.


TM

[David Root]

Thanx TM. I added an edit above re changing the PI entrance cap to .01 from .005 to get a bit more warmth. Did you try that?

[ToneMerc]

Thanx TM. I added an edit above re changing the PI entrance cap to .01 from .005 to get a bit more warmth. Did you try that?

The only value I tried was a .005, simply because that was the value in that OD Deluxe that Brandon posted.

You are looking great there, crank it and enjoy!

TM

[Colossal]

Damn, that's nice...another beauty David! Glad to hear the relays worked out too. I'm getting part envy from all you guys with the veritable treasure trove of parts.

[amplifiednation]

Wow David that build looks fantastic! I have been using the chocodrops too! They sound great

[David Root]

Thanx guys. Taylor, the chocodrops do sound different than 6PS orange drops don't they. Dave, thought I'd give you a plug, WTF!

On the parts, like I said earlier they Costa Lotta these days unless you get lucky, especially the Pihers. There's a guy on Ebay that sells lots occasionally but I haven't seen him lately. Iskra are now in Piher territory too, but the '60s Draloric and Resista can still be had reasonably, if you can find them. All good.

Now if I could just find some cathode bypass caps with mojo!

[M Fowler]

Fantastic build David I like all the expensive caps and resistors.

I like the Colossal boards too.

[jelle]

Awesome builds!!

[rogb]

That is just superb David! Cant wait to find out more and your opinions on the sound etc as you get the relays running.