New ODS 100W build with pictures...

[ic-racer]

Ok, its done!!

Here are the pictures right after I finished.

[ic-racer]

Initial power up:

I was planning wiring together a light bulb on a cord, but after just spending an hour wiring the power cord and fuse in the amp, I figured I don't need to risk electrocuting myself with some hokey 'bulb-on-a-wire' just to protect my little .50 cent fuse.

So, armed with spare fuses on hand I proceeded with initial startup. After checking the polarity of the caps and the diodes for the 100th time I was ready. I also disconnected the transformer secondaries to check the circuit for shorts, and then re-connected them. The FET pot was set to the middle. The OD pot was set to the middle. The PI trimmer was to the middle (checked with an ohm meter) and the bias pot was set for maximum negative voltage. The 50/100 was set to 100. No tubes in place yet.

(You can see a piece of plexiglass over the capacitors...they just look so big they scare me...)

[odourboy]

Been there! Got a variac for free so I don't have to put the amp on an extension cord on the other side of the basement for first power up.

474VDC no load... looking good!

[ic-racer]

So, nothing blew up and the voltages all seemed reasonable. Next I put some tubes in it and set the bias to about 38ma.

I checked voltages again (I don't have them right now, but will post them later).

Next I hooked it up to a speaker and a guitar and.....nothing! So, I hooked a line into the "POWER AMP IN" jack and WOW, the power amp is awesome! Better than my real Fender Twin (though the Fender needs a cap job).

So, back to the bench to find out why the preamp does not work.

[ic-racer]

First thing to check was the input jack. And sure-enough that was the problem. The little red jumper between the FET and NOR jack was hooked to the wrong place on the NOR jack. So, a little surgery and we are back in business....

[ic-racer]

Hooked it up again and STILL no preamp!

Out of curiosity, I could not hear the overdrive relay when I flicked the switch in the back, so maybe this is part of the problem.

Back to the bench to check the relay boards.

Turns out I was not able to follow a signal through either relay!

So I took one out and DUH...the relays are in backwards!

It so happens that the little picture of a DIODE on the relays does NOT go toward the DIODE on the board, it goes the other way. (this was my fault, as Niki ships the relays separate from the boards)

So, swap the relays around and fire it up and it WORKS!!!

[odourboy]

What's the black crap all over your preamp components? You're not trying to make it look degooped ARE YOU??? LOL!

[ic-racer]

What's the black crap all over your preamp components? You're not trying to make it look degooped ARE YOU??? LOL!

I got the impression that he painted them black under the goop. The real goop is still to come, once the tweaking it done. Since every other capacitor in the amplifier is held in place with goop, I am going to hold all the preamp capacitors in place with the goop also (though not as thick as the original, so it WILL look degooped!).

[ic-racer]

First impressions:

Well, I don't much care for 'clean' amps because they don't have sustain that fits my playing style, but boy this thing is different! I love the cleans. In fact, my impression is that the clean channel being so good is what makes the OD so good.

Just about all the settings I tried sounded great. What a surprise, as I was starting to have second thoughts that I could actually build an amp for $700 that was better than my most expensive Boogie.

This thing is really awesome, it is certainly a different experience than every other amp I own.

In terms of 'tweaking,' well, it does not NEED any! But I might experiment a little to see what other kinds of sounds it will get. For now, though, it does not need anything. (Recall that I previously set my OD input as 150k going in to a 357K trimmer).

Negatives:

Loud pop when turning the standby OFF.
As expected, the 50/100 does not do much (maybe there is still enough cathode current through the 'off' tubes that they are still working?) But the little LED in the back sure is cool

Since my footswitch is not done yet, and I have wired the amp like #124, I have not even tried the PAB yet. I'll work on the footswitch tonight
and try to get some sound clips up tomorrow.

[ic-racer]

Been there! Got a variac for free so I don't have to put the amp on an extension cord on the other side of the basement for first power up.

I found myself verifying the charge level in my fire extinguisher also...

[odourboy]

Congrats!! Feels great when a build comes on-line smoothly n'est pas?

Now I feel bad about teasing you over the goop. A word of advice though, finish your tweaking BEFORE you goop!

[ic-racer]

I suspect there is a fine line between selling Fake goods on e-bay and making an exact replica for personal enjoyment.

I can't afford a real Dumble, so I want this one to be as close to the original as possible. But this is for my own personal enjoyment. If this amp ever shows up on the market, it is because someone stole it, or I died and my wife sold it .

Even if it were to ever make it to the market, I would hope that all these pictures of its construction and eventually a place on Rob's public web site under CLONES/REPLICAS, will not let any would-be thief try to pass it off as an original

[heisthl]

Congrats! I would have been disappointed if it didn't work after all the time and obvious attention to detail you've put in.
I bet your half power is working correctly - you can hardly notice any change. If the standby pop is a problem for you can put a .01 or .02 1KV disc cap across the switch contacts.

[ic-racer]

Voltages after playing 30 minutes:

Line voltage AC 124v

B1 = 452v
B2 = 433v
B3 = 416v
B4 = 301v
B5 = 294v

PI plates = blue 288v, brown 285v

V2A = 133v and 2.5v (180k plate, 1.8k cathode)
V2B = 149v and 2.3v (120k plate, 2.7k cathode)
(I was doing a lot of tube swapping, this tube sounded good but may not be a 12 ax7, the markings are long gone. I'll probably re-measure these with a known tube before I go changing anything)

V1A = 183v and 1.6v (220k plate, 3.3k cathode)
V1B = 188v and 1.5v (150k plate, 2.2k cathode)

[dogears]

A couple of questions...

How come you so faithfully followed much of 124, but then used different plate/cathode values? You may decide to try the standard 220K>100K network for OD since you used higher plates.

On that subject, how come you swapped the cathode resistors? That is a mistake unless you had some reason to do it. V2 cathode resistors are backwards... It is also odd that the 120K plate has such low voltage, I would have expected well over 200V with such as big cathode resistor.

Congrats on the great build!

Voltages after playing 30 minutes:

Line voltage AC 124v

B1 = 452v
B2 = 433v
B3 = 416v
B4 = 301v
B5 = 294v

PI plates = blue 288v, brown 285v

V2A = 133v and 2.5v (180k plate, 1.8k cathode)
V2B = 149v and 2.3v (120k plate, 2.7k cathode)

V1A = 183v and 1.6v (220k plate, 3.3k cathode)
V1B = 188v and 1.5v (150k plate, 2.2k cathode)