OTS #102 to #060 (without reverb)?

[ynor]

Hi everyone.

I've been playing guitar since I was 6 and have just discovered the world of D-style amps, after playing for 38 years on almost everything else. I have been playing around modding my own amps as a hobby, but I can't design them or anything advanced, although I do have some education in electronics, not used in decades as I became a surgeon insted. My first experience with this fine forum was 15 years ago when I installed a VVR in a Matchless DC30 and Gabriel Voxer, but now I've rediscovered this forum after obtaining a an ODS, Robben Ford Modern Eagle version from Ceriatone. It is a #102 clone, slightly darker voiced.

I love the amp, but would like to try to mod it in the direction of the Amplified Nation ODR just to ease that itch. If I'm not mistanken, the AN ODR is a clone of the #060. And if I'm not missing much from reading the schematics of the #060 found here (through from 2012, outdated??), the preamp structure of the #102 and #060 is more or less the same except some different values on capacitors & resistors. The big difference would be the reverb section with three more tubes, but if you turn the reverb send all the way down, this part of the signal path is bypassed and goes to a mixer valve. When the reverb is all the way down, the only addition in the #060s signal path compared to the #102 is the triode on the mixer valve (not sure if there is a LNFB there too?) between the preamp and FX loop, which I think would contribute to more harmonics? The recovery stage on a Dumbleator in the FX loop of the #102 could probably compensate some for that missing tube?

My #102 is high plate (220 k) & Skyliner. The #060 has 160 on the V1 plate, according to the schematic I found here. Is this regarded as a high or low plate?

How much difference is there between the AN ODR and the #060? Is there an updated schematic of the #060?

Any thoughts on this? I realize that the difference between the #102 and AN ODR is more than the schematics alone, and there's an art in selecting the right components, thoughtful layout and probably much more than I can think of

[rootz]

Not sure about the differences between AN’s ODR and what we know about #60. Iirc Taylor has been inside that amp. Haven’t seen any pictures of the guts of the AN amp.

That being said, #60 with the reverb controls at zero still has some reverb parts in the signal path or to ground. The mixer is the obvious one. It is a virtual earth mixer. 100% feedback, so acts like a follower, but obviously flips the phase of the signal.

Then there’s the reverb input parts which load the high end a tiny bit.

I think the mixer in #60 is about as clean and transparent as it gets and hasn’t got much of a sound signature of it’s own. So you should be good to try the amp without all the reverb circuitry. I'd expect not much sonic difference from the same circuit with reverb.

[rootz]

#60 is considered an odd ball circuit. The ratio between plate and cathode resistors is not what you’d normally find in an ODS. It is what contributes to its sound though. The hand drawn layout calls for 145V on V1a and 195 or so on v1b. The latter is what you’d expect, the forst one not though. The 180k plate resistor can clearly be seen in one of the pictures. I’d say the hand drawn layout is pretty accurate, as are the voltages.

[ynor]

Interesting points!

Wonder if just replacing the caps and resistors in the preamp part to #060 specs will get the amp close to AN ODR... I don't believe I've seen the hand written schematics of the #060.

[ijedouglas]

Interesting points!

Wonder if just replacing the caps and resistors in the preamp part to #060 specs will get the amp close to AN ODR... I don't believe I've seen the hand written schematics of the #060.

It sounds like you just want to change the plate//cathode resistors. You would probably also need to play with the dropping string to get V1 voltage down. Is there something sonically you are looking for?

The ODR is in essence, just an ODS with added reverb circuitry.

[rootz]

Interesting points!

Wonder if just replacing the caps and resistors in the preamp part to #060 specs will get the amp close to AN ODR... I don't believe I've seen the hand written schematics of the #060.

https://ampgarage.com/forum/viewtopic.php?f=4&t=17935

The pdf's in the first post is what you're looking for. Not schematics, but layouts, like I pointed out. That whole thread is a good read.

As being pointed out: you'll end up with an ODS, because #60 is as close as a ODR gets to an ODS: the reverb is essentially 'in the loop'. But it is a different ODS for sure. Mid plates on V1, with a different setup for V1a, but low plate for V2. If you currently have 440V on the plates of your power tubes, I think a 2k2 --> 22k --> 2k2 --> FET should get you close to the wanted voltages. Keep in mind, V1b should have 195V on the plate. 145V on V1a is a consequence of the 180 plate resistor and 1k cathode resistor, not of a greatly different dropping string.

[ynor]

It sounds like you just want to change the plate//cathode resistors. You would probably also need to play with the dropping string to get V1 voltage down. Is there something sonically you are looking for?

The ODR is in essence, just an ODS with added reverb circuitry.

I'm not quite sure what I'm looking for. My amp sounds very good on the OD channel on both my Les Paul (2020 R0) and my tele (Tom Anderson HTC), but I'm mainly a Strat player and there is some kind of undefinable harshness in the OD channel using my 1964 Strat, and it feels kind of "loose". The LP and teles sound good on almost any high-quality amp I pair them with, but I find Strats to be more difficult on OD channels. I see that Taylor defines his ODR as a low-plate classic based on #60, and the clips I'v seen on youtube using strats sounds more in the direction that I want my strat to sound like on the OD channel. When using the Strat on my ODS, I actually prefer the Synergy OS preamp OD channel over the #102s OD channel. It has a darker more raw tone with a different feel. The cleans sound amazing with both. But I don't know what tone stack the Synergy OD is based on though. Would like to know. I sent them an email but got no answer so maybe I have to open it up and trace it myself.

I found a picture of the insides of the ODR: https://www.guitarplayer.com/reviews/am ... erb-review

I'm getting a D-lator soon that I will try first with the strats. However, changing the plate voltages/cathode resistors is interesting. But Taylor says his ODR has a classic tone stack and my #102 has Skyliner. How much of a difference is the between these two tone stacks?

[ijedouglas]

It sounds like you just want to change the plate//cathode resistors. You would probably also need to play with the dropping string to get V1 voltage down. Is there something sonically you are looking for?

The ODR is in essence, just an ODS with added reverb circuitry.

I'm not quite sure what I'm looking for. My amp sounds very good on the OD channel on both my Les Paul (2020 R0) and my tele (Tom Anderson HTC), but I'm mainly a Strat player and there is some kind of undefinable harshness in the OD channel using my 1964 Strat, and it feels kind of "loose". The LP and teles sound good on almost any high-quality amp I pair them with, but I find Strats to be more difficult on OD channels. I see that Taylor defines his ODR as a low-plate classic based on #60, and the clips I'v seen on youtube using strats sounds more in the direction that I want my strat to sound like on the OD channel. When using the Strat on my ODS, I actually prefer the Synergy OS preamp OD channel over the #102s OD channel. It has a darker more raw tone with a different feel. The cleans sound amazing with both. But I don't know what tone stack the Synergy OD is based on though. Would like to know. I sent them an email but got no answer so maybe I have to open it up and trace it myself.

I found a picture of the insides of the ODR: https://www.guitarplayer.com/reviews/am ... erb-review

I'm getting a D-lator soon that I will try first with the strats. However, changing the plate voltages/cathode resistors is interesting. But Taylor says his ODR has a classic tone stack and my #102 has Skyliner. How much of a difference is the between these two tone stacks?

You may want to first try going to a low plate config (100K/1K5), something like #0124 https://ampgarage.com/forum/viewtopic.php?f=5&t=5719. This is a pretty simple change. This should get you more into strat territory (#0124 was voiced for a strat player). You can also experiment with the #060 V1 plate values (180K/1K8 130K/1K). If this doesn't get you there you may want to try the classic tonestack https://ampgarage.com/forum/viewtopic.php?f=5&t=12872. This is a bigger change but you can probably test it by changing the slope to 100K (if you still have the low plate config, otherwise 150K for high plate), treble cap to 330pf ceramic and mid cap to 0.05. I you like the direction it is going you can continue changing the tonestack over to a classic config.

[rootz]

My #94 sounds very good with a Strat. That one is a high plate classic, so plates and cathodes like #102, but a different tone stack. Loose in the low end? Simple experiment: change only the 10n cap to the mid pot for a 47n. That gets rid of a lot of low end and makes the tone stack like a crossover between a skyline (102) and classic (124). Harshness with a Strat? Maybe the OD entrance isn't well suited for a Strat too. The trim pot is bigger than 100k in #94 and #124. That shaves off more high end going into the OD section.

Low plates like Ian said definitely sounds more Fendery. Less compression, while retaining brightness. Feels a bit more bouncy and suits a Strat a bit better IMHO.

Ian, isn't #60 V1a 180k/1k and V1b 130k/1k8? Instead of 180k/1k8 and 130k/1k?
Changing these resistors should get you in ODR #60 territory immediately.
It is a mixture between mid plate V1 and low plate V2.

Bottomline: experiment

[ijedouglas]

Ian, isn't #60 V1a 180k/1k and V1b 130k/1k8? Instead of 180k/1k8 and 130k/1k?

Yup, it's early here

Edit: Actually, looking at the PDF, I think it is 180k/1k8 and 130k/1k

[ijedouglas]

My #94 sounds very good with a Strat. That one is a high plate classic, so plates and cathodes like #102, but a different tone stack. Loose in the low end? Simple experiment: change only the 10n cap to the mid pot for a 47n. That gets rid of a lot of low end and makes the tone stack like a crossover between a skyline (102) and classic (124). Harshness with a Strat? Maybe the OD entrance isn't well suited for a Strat too. The trim pot is bigger than 100k in #94 and #124. That shaves off more high end going into the OD section.

I'm busy with a #094 / #0128 type High-plate classic at the moment https://ampgarage.com/forum/viewtopic.php?f=4&t=36854. Should be done today. I opted to go with a 100K trimmer but have a 470K (reads 400K) waiting in the wings.

[ynor]

Wow! Thank you for sharing! The knowledge here...
Yes it sounds like I need to convert into either low plate, classic tone stack or both. The LP and tele is not picky and sounds good on anything, so I'll prioritize optimizing the amp for Strat OD-tones.

Forgive me if I'll bother you if the D-lator doesn't do enough for the Strat tones. But I can already see the mods coming! Not because it is essential as the amp is extremely good as it is, but for chasing those last 5% and for the fun of it

[rootz]

So, here's the layout. Clearly visible are the voltages at the anodes of V1a and b. 180k/1k and 130k/1k8 gets you very close to these voltages. 180k/1k8 and 130k/1k gets you to both at 170V, or thereabouts. The latter is not in accordance with the layout.

Also, I added a closeup of the preamp. The only one where I can see the cathode resistor just a bit under the shielded wires. That does not look like a 1k8 resistor. I can see black, black brown and another brown band on the cap of the resistor.

[ynor]

Harshness with a Strat? Maybe the OD entrance isn't well suited for a Strat too. The trim pot is bigger than 100k in #94 and #124. That shaves off more high end going into the OD section.

Changing trim pot is also a good suggestion. Mine has the 100k linear external pot and is easly changed. If I read the layout of the #060 correctly, that also has a 100k pot? I cannot see if the AN ODR has an internal trim pot or a fixed resistor from the inside pic in the link. What value of the trim pot does #94 and #124 have?

Here is the layout of mine

[ynor]

Found it. But can't see OD trim of the AN ODR