Overdrive Deluxe amp

[aab0mb]

My bad I meant the cathode caps on v1 . The low input stage looks like 1u

Yea let me see what I've got and get back with you. I pulled the first one In could get to this morning and am just about done with it, I kinda got lucky, it was semi-finished. What it was, who knows haha.
Thanks for the xformer specs, the one I'm working on has the same PT, but multitapped, 40-18028 , and my OT is the same , but multi secondary 40-18087, 6k6 same

Are we sure the filtering is as is on the current schematic? I didn't check earlier, but can we confirm 5 filtering stages, not 4, like a BF deluxe? I've got the CF and gain stages on the same node in mine, as it'd be a PITA to change it with the existing underboard wiring I've got going on.

Also, IIRC the UP amps had a 500K Bass pot?

Can’t wait to hear some clips. Def let me know on the project amp.

We have no idea on the power supply values or pot values at all. The posted pics are all we have to work with, unfortunately.

I’m sure we can get pretty close with some tweaking and
experimentation. It’ll be the TAG Drive Deluxe haha

Yeah all the UP schematics I have say 500kA.

[Aaron]

Version 3 attached. I think we're getting closer.
Judging by the physical size, the preamp Ck look smaller than the 25uf used through out the rest of the amp. Guessing they could be 5uf?

@Smokebreak3, Taylor has 5 filter stages in his version.

Regarding the HI and LO inputs, still a bit of a mystery. As aab0mb mentioned, can see a resistor in one but not the other? Hmmm.

Thanks,
Aaron

[aab0mb]

Version 3 attached. I think we're getting closer.
Judging by the physical size, the preamp Ck look smaller than the 25uf used through out the rest of the amp. Guessing they could be 5uf?

@Smokebreak3, Taylor has 5 filter stages in his version.

Regarding the HI and LO inputs, still a bit of a mystery. As aab0mb mentioned, can see a resistor in one but not the other? Hmmm.

Thanks,
Aaron

I think Smokebreak was suggestion that the low input ground ref might be 470k and the resistor feeding into the low input might also be 470k thus creating a voltage divider. However this is pure speculation when discussing need to control gain between stages. The overdrive pot value will also affect said gain stage.

The low input stage V1b has a 1uf 25v cathode bypass cap. If you look closely it’s visible.

Can you guys read this power supply dropping resistors? I’m wondering if there’s some Dumble magic there. The 22k dropping resistor in some ODS amps has been said to contribute to the feel and note flipping heard in those amps.

Dave G, talks about it here. https://ampgarage.com/forum/viewtopic.p ... 49#p144049

[Smokebreak3]

I got the amp fired up last night. As advertised, super fun to play. Tremolo is insanely good and throbby, I like the reverb, its kinda soft.
I'm going to experiment with the unknowns today and hone it in:

Currently I have the OD divider setup as I originally described, 470Ks and 250k OD pot
OD stage 2k7/5u and lo input stage 2k7/1u. I'll try both with 1u

Once you get some volume on it, it takes off into feedback. I'll stick a good alnico in it today, I have a creamback that may work

I need to get my PS like the AN amp. We can pretty reliably say that's accurate, I imagine
Looks like 50uf>choke<20uf>10K>20uf>22K>20uf>10K>20uf . Those are typical marshal values

[Smokebreak3]

Here's my observations after playing the amp today and trying different things:

-The Clean side is just gorgeous. It has the same qualities as the clean UP amps. I threw every guitar I could at it and they all sounded great. Awesome edge of breakup sounds

-The OD takes a minute to dial in , and I feel like it's close but not quite there yet. It's interesting that in a lot of the descriptions of the clones it always says something like "bordering on pushed fuzz tones", or something like that. That is definitely true. Not fizzy, but fuzzy if the OD control gets past 2 oclock. I went back and watched the original vid, and the OD is on like 4, with the level and master dimed. I haven't been able to get it that loud to check!

-I found a 1M OD pot sounded better than the 250K I had in there. It thickened up the OD

-the treble cap should probably be 250p, with the 56K slope. I liked it better than the 500p. I realized none of the values can be seen in the pics.

-1000p mid cap was like a "too bright" bright cap.....a 2200p on top of the 250p provided a good mid boost that isn't too bright

-amp sounded better with both preamp bypass caps at 1u . The amp is already really fat sounding, a 1st stage 5u was just too much

- I screwed up and put the bright cap over the pot feeding the CF, but it works great there too!!

-That accent, even though correctly transcribed on the schematic from the pics, doesn't make much sense to me, and doesn't really do a whole lot to the high end at all. It literally changes the value of the tail resistor as you turn it. So at zero, it grounds out the NFB. It sounds best a zero on the clean channel, and on 10 for the OD channel, as it's benefitting from some NFB there. I'm not convinced that's not a mistake in the cloning of the amp. Perhaps that's why the other just has a 4k7 tail. I need to try it like a 5f6a presence. I feel like this area, along with the speaker, is crucial in getting the treble content correct

[bepone]

-That accent, even though correctly transcribed on the schematic from the pics, doesn't make much sense to me, and doesn't really do a whole lot to the high end at all. It literally changes the value of the tail resistor as you turn it. So at zero, it grounds out the NFB. It sounds best a zero on the clean channel, and on 10 for the OD channel, as it's benefitting from some NFB there. I'm not convinced that's not a mistake in the cloning of the amp. Perhaps that's why the other just has a 4k7 tail. I need to try it like a 5f6a presence. I feel like this area, along with the speaker, is crucial in getting the treble content correct

for me is mistake too.. just spend 30sec an wire it normally, 100nF cap to the mid viper only, and 5k max value of the pot to PI/NFB connection

[bepone]

I feel like this area, along with the speaker, is crucial in getting the treble content correct

yes..sometimes i'm changing speakers all day to get the tone wanted

[aab0mb]

- I screwed up and put the bright cap over the pot feeding the CF, but it works great there too!!

I think this is actually correct. There is a twisted black pair of wires coming from that switch to the second gain pot.

Interesting report about the clean channel. I still wonder if 470k input impedance is correct. Seems against best practice.

Did you use a treble peaking bypass cap on the 220k or leave it out?

[Smokebreak3]

For the treble peaking I had settled on only one from the verb side, which acts as a high end dump for the dry signal, but today I took it off. That is certainly a spot that will vary with different speakers

Yea that bright cap is way to big to be of use on the MV.

Yea that pot, resistor, resistor for the OD is crucial , but it seriously looks like there is not a grid resistor for the low input jack! The amp simply couldn't function in low gain mode without one though.
I was speculating on the 470K input resistor, as that would make a simple 470k divider, a very marshally thing.
Maybe the OD pot is 100K and the resistor is 10K, which would make it omittable.

[aab0mb]

For the treble peaking I had settled on only one from the verb side, which acts as a high end dump for the dry signal, but today I took it off. That is certainly a spot that will vary with different speakers

Yea that bright cap is way to big to be of use on the MV.

Yea that pot, resistor, resistor for the OD is crucial , but it seriously looks like there is not a grid resistor for the low input jack! The amp simply couldn't function in low gain mode without one though.
I was speculating on the 470K input resistor, as that would make a simple 470k divider, a very marshally thing.
Maybe the OD pot is 100K and the resistor is 10K, which would make it omittable.

-As far as I can see, the bright cap is on the pot feeding v2 labeled “level”. Not the master pot, not the drive pot. It makes sense there because you get some sparkle on the clean channel.

-Correct me if I’m wrong but without the 100k off the wiper of the drive pot, the 1m (or470k) grid leak is riding directly on the wiper of the drive pot and changing its value as well as the grid leak value. So 1meg pot turns to 500k max, 500k turns to 333k max and 250k turns to 200k max value. Double duty. I’ve seen similar in the blues junior schematic. 130k hanging on the wiper of the first volume pot being used to dump some gain. Something to think about when experimenting.
https://www.thetubestore.com/lib/thetub ... ematic.pdf

Also the Marshall 1959rr “one wire mod” amp is essentially the same topology so it might be worth a look for ideas.

[Smokebreak3]

Correct, but the grid leak value(as it applies to the lo gain side) wouldn't be changed by the pot value or rotation bc the switching contact would be open.
But yhes, whatever the grid leak is would affect the pot value in OD mode. That is a device used in higher gain amps, a Fortin or maybe Cameron trick is to hang a resistor off the wiper of a gain pot, and it tightens up the OD. I think he called it "feel". Anyways, yes that's a good point and something to think about.
In OD mode the signal doesn't "need" the Lo gain input's resistor, as the pot does that job, regardless of whether there's a resistor cominfg of the wiper.

Right now I've got a 100K pot with a 15K feeding the jack, with a 1M standard leak, and I like it

I'm going to put a 1M trimmer wired as variable resistor coming of the 100K OD pot I have in there now and see where I land

[aab0mb]

Correct, but the grid leak value(as it applies to the lo gain side) wouldn't be changed by the pot value or rotation bc the switching contact would be open.
But yhes, whatever the grid leak is would affect the pot value in OD mode.
In OD mode the signal doesn't "need" the Lo gain input's resistor, as the pot does that job, regardless of whether there's a resistor cominfg of the wiper.

Right now I've got a 100K pot with a 15K feeding the jack, with a 1M standard leak, and I like it

Yeah awesome, we’re on the same page.

The nice thing about having the resistor hanging off the wiper in OD mode is that the grid reference isn’t dependent on the wiper contact. A little bit of extra insurance just in case the pot fails.

I feel like 15 K feeding the jack is insignificant and it can go right on the tube pin instead.

[Smokebreak3]

Ok I took one for the team and made a couple clips with the amp at volume. It's ridiculously loud, but once I got it there I realized it was doing the thing we're all lookin for....at least very close.
My sloppy playing reflects the fact that I was completely a deer in headlights, as I was shocked it was doing the thing, plus the sheer volume of it all... I only lasted 30 seconds or so
Master on 10, Volume on 10, OD around 5.
It's interesting, with the amp cranked, the OD control really controls the wildness of the amp. On 4, it sounds great, but doesn't feedback at will. Almost polite!
Once you get to 5 or 6 on an alpha audio taper pot, it starts to feedback, and that's as high as I got it. I kinda freaked out and shut er down haha.
I've got some regular old jj preamp tubes in there and some NOS RCA 6V6s I've been saving for something. The power tube distortion is where all of that low mid mojo comes from.
The only difference in the clips is where my iphone was in relation to the alnico cream speaker in the deluxe cab.
Schematic is where this amp was at time of video

OVERDRIVE DELUXE 1.2 (1).png

[aab0mb]

Ok I took one for the team and made a couple clips with the amp at volume. It's ridiculously loud, but once I got it there I realized it was doing the thing we're all lookin for....at least very close.
My sloppy playing reflects the fact that I was completely a deer in headlights, as I was shocked it was doing the thing, plus the sheer volume of it all... I only lasted 30 seconds or so
Master on 10, Volume on 10, OD around 5.
It's interesting, with the amp cranked, the OD control really controls the wildness of the amp. On 4, it sounds great, but doesn't feedback at will. Almost polite!
Once you get to 5 or 6 on an alpha audio taper pot, it starts to feedback, and that's as high as I got it. I kinda freaked out and shut er down haha.
I've got some regular old jj preamp tubes in there and some NOS RCA 6V6s I've been saving for something. The power tube distortion is where all of that low mid mojo comes from.
The only difference in the clips is where my iphone was in relation to the alnico cream speaker in the deluxe cab.
Schematic is where this amp was at time of video

OVERDRIVE DELUXE 1.2 (1).png

Great work! Sounds like it’s really fun to play. Cool how it feeds back and sings like that.

I’m wondering if a 1meg trim pot at the inline 15k might be a good thing for testing. Shaves some highs off if needed and keeps v1b from splatting out. It seems like the original vid had a bit less high/mid content but that might be guitar, speaker, amp settings, etc.

What were the EQ settings like? Same as the original vid?

[Smokebreak3]

Yea I aped the original vid eq settings. I put a 1M variable resistor pot inline with the 15K to test. When the master was low, it definitely helped to add resistance and take away harshness, but when the master was cranked it dulled it. But that's the place to smooth it out if you want.
We're definitely chasing some things beyond our control...Guitar, speaker, player, iphone compression from 15 years ago, etc