2nd gen ODS with Erwin chassis.

[erwin_ve]

Really enjoying this amp. In the meantime I have made a headshell and combo cab (just need to make a front baffle to complete). Details of the circuit to date to follow, including a master (hope Erwin doesn’t mind me drilling his lovely chassis ).

Lovely and great looking amp. That master is similar to #022. Despite your drilling it still looks good

[Dr d]

Really enjoying this amp. In the meantime I have made a headshell and combo cab (just need to make a front baffle to complete). Details of the circuit to date to follow, including a master (hope Erwin doesn’t mind me drilling his lovely chassis ).

Lovely and great looking amp. That master is similar to #022. Despite your drilling it still looks good

Great chassis! Thank you for your kind words. “ That master is similar to #22”….

[Dr d]

Ok, so here is what I think is the final circuit. I tried out a number of things and came to this conclusion.
Firstly, I oriented the foil ends of the caps toward the pots as per #40.
Second, I changed the mid pot to a 715P for a “clearer” mid range.
Third, the V1 & V2 plates made a massive difference to the overall tone of the amp. Modern Dale RN65ds are very warm and smooth. I mainly use a Les Paul so I found the brighter Electra/Mepcos worked best for me. I think Koa Spears would be a good alternative.
Fourth, I upped the GNFB resistor to 2k2 to open the amp up a bit.
Fifth, I upped the accent cap to 2n2 with no attenuation via the trim pot I applied.
Six, I found the V1 and V2 voltages were very responsive and 185v V1 and 195v V2 worked perfectly for me.
Seven, I replaced the James pair of caps for a single 0.0022uf cap across the outer tabs to give a smoother bass response.
Eight, I found the G1265 sounded good and the EVM 12L perfect.
Finally, I added a master vol using the Hybrid/Bluesmaster system which, again, works perfectly.
I have to say that this amp is stunning. The variety of tones that this amp gives is amazing. I use a Dumbleator to further shape the tone. With the send set low and recovery set high, it brightens the overall tone. The opposite darkens the overall tone and then everything in between.
I hope this is of interest/help to anyone. Great amp. Highly recommended!

[ijedouglas]

That looks amazing!

[Raoul Duke]

More great info Doc. I’m still fine tuning mine and this is really helpful. Very much appreciated!

Your build looks great

[Dr d]

That looks amazing!

Thank you very much! Enjoying watching your build.

[Dr d]

More great info Doc. I’m still fine tuning mine and this is really helpful. Very much appreciated!

Your build looks great

Thank you for your kind words. I’ve learned everything I know from this forum and are only too pleased to share/help where I can……and if I don’t know something, I ask!

[dbharris]

This is certainly a top tier build! Looks fantastic.

-Dan

[Dr d]

This is certainly a top tier build! Looks fantastic.

-Dan

Thank you Dan. I’m enjoying watching your build come together!

[Dr d]

Another quick update. I did a very brief bit of experimenting with the 1m2 bypass resistor on the funky OD entrance. Last time I was in the amp I put a 670k piher in series with a trim pot and liked the sound set to a total resistance of about 920k. I decided to reduce that resistance further to about 750k and found that more gain yielded a fatter tone. This would great if you were tuning for a single coil….however I predominantly use a Les Paul and I found I had lost a considerable amount of bite. So I decided to go back to the original resistance of around 920k. However, instead of returning the piher and trimpot, I decided to put in a 951k mepco mf6. The clarity and bite returned and then some. The OD tone is sweet and responsive and sings in the way we would want a Dumble OD to do. I am delighted and am determined not to do any more tinkering! Btw, the Mepco is considered on here to be a bright resistor and Pihers warm/smooth, so I would guess a Koa Speer would work well.
Btw, the valves are GE12ax7a/7025 > ( I initially had a pair of EHs in the first two slots and they sounded pretty good actually) Ge12ax7 > Ge12at7 balanced > pair of TAD 6L6GC STRs.

[Dr d]

I finally got around to finishing the combo cab. The sides are made from recycled solid timber which I think is a light weight hardwood of some sort. The front baffle was initially made from the same timber but it proved to be too unstable with a big hole in the middle of it. The front is now 18mm birch ply and the rear baffle is 1/2 inch ply. The covering is faux suede which was applied to the timber with water based contact adhesive.
My method of applying the grill cloth is to wet the cloth and then tack it in place with drawing pins. I then make sure I am happy that everything is lined up before stapling and trimming. As the cloth dries out, it shrinks to give a nice tight finish. Having studied a few photos, it looks to me that for the front baffle, HAD liked there to be wood on wood contact between the baffle and the cleats. The rear baffle has a layer of covering in between. The result of the above is a lively and well balanced cab. The amp itself has absolutely come alive in this cab and there is no sign of harshness. I believe Ian has come to this conclusion also. Btw, the EV speaker is, in my opinion, absolutely key in getting the true voice out of these amps. I tried a trusty G12-65 and the amp sounded lifeless in comparison to the EV.
Next up I will try a 3rd gen conversion with some lovely 70s Dales that a generous forum member kindly sent my way.

[dbharris]

Looks great! Very interesting note about the cab construction. I'll have to take a peak inside mine and see how they were built.

-Dan

[Colossal]

Nice work, Doc!

[ijedouglas]

Great job on the cab! Looks stunning!

I tried the same with the grill cloth (wetting it) and it worked great.

Great job on getting the half diamonds in the top left corner (same as HAD )

[Dr d]

Great job on the cab! Looks stunning!

I tried the same with the grill cloth (wetting it) and it worked great.

Great job on getting the half diamonds in the top left corner (same as HAD )

I always aims to please!