non-HRM Findings

[Funkalicousgroove]

FWIW, 190v is not gospel, Dumble #192 has 217 on V1a, and sounds fantastic.

Funk

[ayan]

I like the cleans quite a bit better with lower plates. But even with 220/150 plates on the OD tube, I seem to lose a bit of the definition in overdrive with the lower CL plates. This seems most noticeable when the OD gain is set fairly low, when you're just trying to put a little hair on the notes without full-on distortion. Is that in keeping with other's experience?

I also think I remember some similarity between low plate cleans with 44M/.05 LNFB and higher plate cleans without LNFB. However, this is not based on direct A/B comparison. If this were true, it might enable the "best of both worlds" approach since one could switch the LNFB on and off. Does that similarity ring any bells for anyone else?

Well, I know that I resisted the 100K resistors a almost a decade ago, I didn't like the sound, period. But then tried it again last year and I think they sound great too. In my case, the biggest differences are: (1) I think the cleans are more elegant with 100Ks, as you do; (2) The overdrive with the 100Ks BEGS to be played at louder volumes than it does with the 220K/150K combo. The sound will not be as smooth, but if I had to compare it to something, I think the 100K plate sound is the closest thing to the "Talk to Your Daughter" overdrive tone, which is pretty gnarly.

* * *

For all of those who chase the RF sound, I have a new piece of trivia and I forget exactly where it came from. I know that I was talking shop with someone a couple of weeks ago and the name Steve Trovatto came up. I have a video of Trovatto playing his own Dumble with a Strat, and RF is also on the bandstand with his Dumble and a MIJ Esprit. Trovatto's tone is about as good a Strat tone on that as I have EVER heard. Anyway, this person (who was it??) told me that RF has been known to borrow Trovatto's Dumble for recording purposes. Added to that, we know that he uses Jackson Browne's Dumble(s) for recording too. Conclusion: you never know which amp you're listening to when you play a RF CD.

Cheers,

Gil

[greiswig]

FWIW, 190v is not gospel, Dumble #192 has 217 on V1a, and sounds fantastic.

Funk

I take it this amp has low plate resistors at least on the clean side? Is it the typical 100k/1k5 thing?

[greiswig]

[Well, I know that I resisted the 100K resistors a almost a decade ago, I didn't like the sound, period. But then tried it again last year and I think they sound great too. In my case, the biggest differences are: (1) I think the cleans are more elegant with 100Ks, as you do;

Thanks, Gil. Have you tried a higher plate clean stage without LNFB?

[ayan]

[Well, I know that I resisted the 100K resistors a almost a decade ago, I didn't like the sound, period. But then tried it again last year and I think they sound great too. In my case, the biggest differences are: (1) I think the cleans are more elegant with 100Ks, as you do;

Thanks, Gil. Have you tried a higher plate clean stage without LNFB?

Yes, I have, since I built a few HRMs (that I eventually ended up returning to non HRM status). I must admit I like the NFB loop on V1B for both clean and dirty, with high and low plate values. I liked the tone of the BM preamp clean side, without the NFB of course, but I couldn't get along with the OD and let alone with the PAB in that amp, so I ripped it out too.

With the Classic or Skyliner preamps, however, to me the NFB is simply part of "the sound."

Gil

[Funkalicousgroove]

FWIW, 190v is not gospel, Dumble #192 has 217 on V1a, and sounds fantastic.

Funk

I take it this amp has low plate resistors at least on the clean side? Is it the typical 100k/1k5 thing?

Nope, it's 220, 150.

[greiswig]

FWIW, 190v is not gospel, Dumble #192 has 217 on V1a, and sounds fantastic.

Funk

I take it this amp has low plate resistors at least on the clean side? Is it the typical 100k/1k5 thing?

Nope, it's 220, 150.

Thanks, Brandon.

I've got one of the TUT books, I've read Aiken's site, I've explored here, but I must just be dense. Because I'm still confused about some very basic things. Maybe I'm even asking the wrong questions, but...

Changing one variable at a time, can someone fill in the blanks (well, parentheses) for me?

1. If I boost the plate voltage by changing the dropping string
a) gain (increases?)
b) tone (gets brighter? no change?)
c) touch sensitivity (increases? decreases?)
d) headroom (increases?)
e) overdrive changes (how?)
f) anything else?

2. If I decrease the plate/cathode resistors from 220k/150k pairs to 100k/100k pairs and keep the P:K ratio at 67:1
a) gain (decreases?)
b) tone (is a bit more bandwidth limited)
c) touch sensitivity (increases?)
d) headroom (increases?)
e) overdrive changes (how?)
f) anything else?

Then there's the interaction between these two, since lowering the plate resistors boosts the voltage...

[skyboltone]

I really would like to see this thread and Funk's fine tuning/blueprinting thread compiled and posted to files. There is just so much going on here it's tough to absorb it all looking at a screen. I'm old enough that the printed page still works better as a reference than searching through a multi page thread.

Again, all great material. Suitable for framing.

Dan

[TimS]

I was thinking the same thing, only with the 100k on CL1/2 and 220k/150k on OD1/2.

It would also be interesting to see how low values in the clean section and high values in the OD section would compare with "in between" values in both.

This one hasn't been revisited in awhile. Did anyone ever try these combinations to see if there was a good balance between the low-plate cleans and the high-plate OD?

I tried that lineup in my most recent (non-HRM) build. I tried it with varying combinations of K bypass caps from 4.7 to 10uF. (I had some spring clips installed on my preamp board on loan from Mark to facilitate component chages, so over a period of weeks, I tried tons of combinatons). With 10uF on the V1A and 5.6uF on V1B (4.7 on each of the OD) I was pretty happy.... it almost stayed.

Which lineup are you referring to - Fischerman's "180k/120k on CL1/2 and 220k/150k on OD1/2" or my "100k on CL1/2 and 220k/150k on OD1/2"?

[benoit]

Well, I know that I resisted the 100K resistors a almost a decade ago,

I like it! Give 'em a taste of their own medicine, I say.