Two Channel Dual Rectifier Issues

[Third Age Amps]

I Stupidly turned on my Dual Rec with no speaker plugged in and now the Orange channel has a loud oscillation and the Red channel has no sound. Think I damaged the OT?

 

[fluff191]

Doubt it. Grammys either work or don't work. Probably popped a phase inverter tube and maybe a power tube. Change out the PI for a start and go from there.

 

[Third Age Amps]

I changed out all of the tubes one at a time and took out the rectifier tubes to eliminate them. Still oscillating. Time to break out the meter and start chopsticking ...

 

[Third Age Amps]

One signal leg of LDR9 was shorted to one signal leg of LDR10 effectively creating a feedback loop from the top of the Orange tonestack back to the C33/R277 junction (oscillation) in the Orange channel and grounding the signal in the Red channel.

Those stacked LDR's can really mess with you if they get a little sideways.

She sounds great now and I can finally start the Bias Mod and my "Thunk Mod".

 

[boss4]

Thunk mod?!

 

[Third Age Amps]

Yeah, it's just the first word that popped into my head when I was playing the amp after I finished the mod. I just makes it sound more balanced and less scooped.

 

[boss4]

But what are you modding? That mod consists in what?

 

[domct203]

Yeah, it's just the first word that popped into my head when I was playing the amp after I finished the mod. I just makes it sound more balanced and less scooped.

But what are you modding? That mod consists in what?

Yes, please share.

Dom

 

[Third Age Amps]

I change C31 and C32, 1uf Tantalum Cathode bypass caps to .47uf Mallory 150M Film caps and change C33 to a 1uf film as well. Getting rid of the low end from those first two stages really tightens it up and brings out the Mid and High-Mid frequencies. Orange Drops would sound just as good, I just have a bunch of the Mallory's in stock.

I remove the Bright caps on the "Gain" pots. If you do leave them, change them to Orange Drop .001uf/400v caps. OD's sound much better than ceramics IMO.

I swap the Ceramic Treble caps for Mica or sometimes an Orange Drop .002uf and .001uf in series for the Red channel Treble cap. That smooths out the treble a bit more than the Mica.

I swap C9 .002uf Mica cap for an Orange Drop .002uf, again to tame the brittle high end.

I add an OD .001uf/600v in parallel with R221 Anode resistor to cut the fizz down.

I try to shape my tone to more of a "Rhythm" sound for maximum thickness, not necessarily for cutting through the mix with a solo. The Dual Rec's have the "solo" tone down pat, I just feel it's a bit brittle and buzzy for chugga-chugga and chord work. A really great speaker set I just started using is matching the WGS Veteran 30 with their ET65 in my 2x12. It is probably the best, most rounded tone I've ever heard live. The Veteran 30 has that classic High-end and bass like the Celestions, but without the "ice pick" EQ spike. The ET65 fills out everything else in the EQ spectrum. I thought I'd never use a V30 type speaker again, but this setup has made me rethink that.

Let me know if you need a marked up schematic or pics and instructions. I've done this mod to three Dual Rec's and the other two owners LOVE the tone.

 

[JCDenton6]

That sounds killer, sounds like something I should look into in the future. Man I'd love to hear before/after comparisons

 

[boss4]

Looks like you know what you're doing. Seems like many recto owner would like a mod like that (me included). I think the recto tone (at least the 3ch models) is too dark and could have a more refined,focused and sharp sound. Not necessarily for solos but to play fast metal rhythms without it getting "sloppy". To get the tone I want I need to put some pedals!...Some sound clips would be very nice!

 

[APEMAN]

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[boss4]

Hi,

I just want to add the advice that there are 666 ways to change/mod the circuit - but the problem here is to find THAT one way that doesn't change the original recto-feel of the amp.

The easiest thing in the world is to look at the schematics of an another amp you like ... the bogner xtc maybe ... many parts of the circuit are identical and by changing 5-10% of your recto you can have the glorious xtc sound and feel - maybe everything is better than.... but its not a recto anymore.

As mentioned the problem is to mod without messing up the amp's character....

I modded an old 3CH DR to sound more like a Roadster / 2CH .... it was not so easy.

Best wishes

Good point of view. I agreed in modding the amp but leaving is natural tone.
To sound like a Roadster/2CH? As far as I know this two have very different tones and distinct voices.

 

[APEMAN]

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[boss4]

Sounds good, and I understand you perspective now. Some clips would be very nice for everyone listen your efforts.