non-HRM Opinions Sought

[ayan]

All,

I'd like yout to please share your opinons with me on the following non-HRM topic: amps with 100K plate load resistors and 1.5K cathode resistors vs. amps with 220K/150K plate load resistors and 3.3k/2.2K cathode resistors. I think there is an overall concensus that the 100K/1.5K amps yield a better clean sound, but the jury seems to be out with respect to the OD channel. With that in mind, I would welcome comments on the overdrive tone only, with regards to:

1. Which configuration sounds more (or less) compressed?

2. Which configuration has more (or less) sustain (as it relates to harmonics, not compression)?

3. Which configuration sounds more (or less) harsh?

4. Which configuration has more (or less) amount of overdrive available on tap?

And one question about the clean channel: which configuration produces more clipping in clean more?

Thanks in advance,

Gil

[TimS]

I'm interested in this myself.

[LeftyStrat]

Color me interested also...

[Bob-I]

All,
I think there is an overall concensus that the 100K/1.5K amps yield a better clean sound,

I don't know that I agree. In fact IME the 100k/1.5k breaks up sooner than the 90's configuration.

but the jury seems to be out with respect to the OD channel. With that in mind, I would welcome comments on the overdrive tone only, with regards to:
1. Which configuration sounds more (or less) compressed?

2. Which configuration has more (or less) sustain (as it relates to harmonics, not compression)?

3. Which configuration sounds more (or less) harsh?

4. Which configuration has more (or less) amount of overdrive available on tap?

Again, IM Limited experience the 100k has a chunky crunchy tone/feel as opposed to the 220k etc which is smoother and more harmonically rich.

And one question about the clean channel: which configuration produces more clipping in clean more?

Thanks in advance,

Gil

More clipping, kinda harsh clipping from 100k/1.5k.

I've only experimented with the 100k/1.5k a few times. I have a 3 channel amp that has one channel 100k/1.5k with a Fender tone stack and the other 2 are HRM config. The 100k channel breaks up much earlier than the Dumble clean, plus it has more of a crunch rather than smooth OD.

I also took my Super Reverb clone and converted to a 70's style Dumble without removing the trem and reverb (a mistake that'll change when I get some time). Again, the OD was chunky and crunchy, not typical Dumble. I converted Rp/Rk/Ck to 90's values and it's far smoother, but unless I bypass the trem/Reverb it's not very smooth.

That's all, I hope more folks will jump in as I'm interested in more viewpoints too.

[dogears]

The 100K plates have a lot more clipping. They seem to not have the harmonic content of the higher assymetrical plates to my ears though. The 100K is a little brighter and unless you use 10uf-22uf bypass caps, seems to thin. Also, the .05uf CL2 works well with 100K plates, but somehting like .02uf works well with the higher plates.

I find the 100K plates to be edgier. I love the cleans of the higher plate loads. The 100K break up real early. Plus, as Bob-I said, the higher plates yield a rich deep clean. Especially with no feedback.

Having said all of this, I would love to have one amp with the 100K plates just for variety......

[Buschman]

Will the 100k plates have more of a traditional Bassman tone. I am missing that a bit but I am still playing with speaker selection. I am also going back to Blackplate 6l6s. Do the 100ks mess up the smooth overdrive tone?

[ayan]

The 100K plates have a lot more clipping. They seem to not have the harmonic content of the higher assymetrical plates to my ears though. The 100K is a little brighter and unless you use 10uf-22uf bypass caps, seems to thin. Also, the .05uf CL2 works well with 100K plates, but somehting like .02uf works well with the higher plates.

I find the 100K plates to be edgier. I love the cleans of the higher plate loads. The 100K break up real early. Plus, as Bob-I said, the higher plates yield a rich deep clean. Especially with no feedback.

Having said all of this, I would love to have one amp with the 100K plates just for variety......

Interesting because my experience with the 100K amps was, after I was hipped to the higher resistor values, to never bother again... and that was 1999. However, recently I have been told by many people whose opinion I respect that the 100K amps are the "shite." Couple of quotes:

1. "The 100K amps cop the LC tone."

2. "RF's amp was a 100K amp until 'Handful of Blues'"

3. "100K amps totally sing in clean mode"

Of course, I have to admit that #124, which I got to play myself, sounded terrific and as the pictures I took show, it is a 100K amp. So I am scratching my head a bit on this one, wondering if it's worth going back into one of my amps and give the 100Ks another try.

Thanks for all the responses,

Gil

[talbany]

I've built a 100w 6L6 version based on #124 w/100k /1.5k in both clean and OD. The thing I liked about it was the shift between clean and OD channel was real transparent, not much of a tonal change other than the OD getting thicker the added gain and compression and a nice singing quality(Talk to you daughter thing). I liked it alot and it being 100 watts the clean channel still had plenty of headroom for me. One thing to note If you use a good bypass cap say the black or silver sprague atoms and not the cheap xicons or nicheons makes a big differance in the smoothness of the breakup. Real noticeable in the clean channel.
Just one man's opinion.

[JamesO]

I placed a Mouser order this afternoon with 220/150 plate resistors and 1.5k cathode resistors, with 1uf/4.7uf on V1 and 4.7uf/4.7uf bypass caps on C2.

I wonder what the result will be on that?

[Darkbluemurder]

Great idea to start this thread.

I have not yet tried the different values on dumble circuits so I cannot comment on the OD tone. For clean tones the higher values have more headroom to my ears.

[dogears]

Gil, I agree that the 100K amps have something. That is why BM and I are doing a couple of amps with them and the MM trannies

It is true that the OD channel becomes an extension of the cleans. The breakup on the cleans is not a bad thing, just different than the higher plates.

I do submit the secret of these amps are the higher bypass caps on V1.

When you previously tried the 100K plates, did you use a Skyliner stack and big bypass caps? If not, then you should revisit.....

The 100K plates have a lot more clipping. They seem to not have the harmonic content of the higher assymetrical plates to my ears though. The 100K is a little brighter and unless you use 10uf-22uf bypass caps, seems to thin. Also, the .05uf CL2 works well with 100K plates, but somehting like .02uf works well with the higher plates.

I find the 100K plates to be edgier. I love the cleans of the higher plate loads. The 100K break up real early. Plus, as Bob-I said, the higher plates yield a rich deep clean. Especially with no feedback.

Having said all of this, I would love to have one amp with the 100K plates just for variety......

Interesting because my experience with the 100K amps was, after I was hipped to the higher resistor values, to never bother again... and that was 1999. However, recently I have been told by many people whose opinion I respect that the 100K amps are the "shite." Couple of quotes:

1. "The 100K amps cop the LC tone."

2. "RF's amp was a 100K amp until 'Handful of Blues'"

3. "100K amps totally sing in clean mode"

Of course, I have to admit that #124, which I got to play myself, sounded terrific and as the pictures I took show, it is a 100K amp. So I am scratching my head a bit on this one, wondering if it's worth going back into one of my amps and give the 100Ks another try.

Thanks for all the responses,

Gil

[ElectronAvalanche]

Hi Gil,

2001 I built a preamp that sported the 220k/150k preamp and a totally seperate 100k/1k5 preamp that had a relay so that I could switch between these two versions. Bear in mind, that I used the Skyliner stack only in the 220k/150k preamp.

I did not use the large cathode cap values back then, since I sticked to the schematic I had back then (no fantastic Dogears tweaks back then, man that could have helped me a lot!!)

The 220k/150k/3k3/2k2 Cleans were a bit smoother, but I really liked the 100k/1k5 Cleans better. The OD was much better (smoother) with the 220k/150k plate resistors, the 100k/1k5 had a harsh sound, that had some holes in the OD. Don´t know how to explain this, but think about a Hiwatt amp distorting (100k/1k5) in comparison to a creamy Marshall (220k/150k/100k/1k5).

The Cleans can be much improved in the 220k/150k by omitting the LNFB. This helps the PAB as well me thinks.

The 220K/150k plates lead to a sound that is smoother with a more pronounced lower mids and a slightly reduced low-treble frequencies, whereas the 100k/1k5 is more "aggressive", cuts better in a band situation, but can be quite too much when playing softly at home.

Now back then I used to take the signal from the aforementioned preamp through a Dumbleator into a 2x6550 Leslie 147 power amp (12AU7 driver) into the 15inch woofer of the Leslie and man what a sound that was. Another setup consisted of the Preamp driving a 2xEL84 Hammond tube main amp (AO-39 from a A-100 organ) into two 12 inch Rolas. Very nice!

Cheers,

Dominik

[dogears]

Actually, Dumble used big caps in the degooped amps I have seen. So, it is not my ears!

I did not use the large cathode cap values back then, since I sticked to the schematic I had back then (no fantastic Dogears tweaks back then, man that could have helped me a lot!!)

[ElectronAvalanche]

Actually, Dumble used big caps in the degooped amps I have seen. So, it is not my ears!

LOL Scott,

back then I could only dream about having an inside pic and/or a set of dogears.........


Btw: has anybody ever got around to try the "Starve" switch found on some early Dumbles? It messed with the PI and resulted in a VERY Marshallesque sound with a major drop in volume.

Cheers,

Dominik

[jelle]

Dominique,

Have you tried increasing the PI cathode resistor like the Mojave amps and Budda do? The sound gets a bit dark when attenuated heavily with this mod. Larry advised us to use a .0047 or bigger pi cathode bypass cap to cure this. I have not tried this yet..


Is this what you are talking about?

Jelle