I am confused.... The V1a cathode resistor should be a 2.7k Was it a typo? My suggestion was to reduce V1a to 180k/2.7k and definately do not touch V1b. That stays at 150k/2.2k
Also, adding a 100k tail to the bleeder has no effect on the tone unless you run the bleed trim at 100k or less, which nobody I know ever does. It aonly changes the sweet range of the trimmer by making your max bleed 100k above ground. If the amp got fizzy, you did something wrong. pin 6>.001cap>250k trim>tail resistor>ground. Same thing applies to the comment about 100k pot versus fixed divider. Same exact tone if hooked up correctly assuming pot set at 50%.
paddes53 wrote:Yesterday I had some time to make a few changements so here's the outcome :
I changed V1a and V2a to 180k/1,8k but I actually didn't notice that much of a difference, so I guess I'll just leave it at that.
I also tried to add a 100k tail to the bleeder circuit but this I didn't like at all, the amp became much more fizzy sounding sout out it went again.
I am actually quite happy with the sound of the amp right now, it's just that somehow I can't really get to the last few percent which are missing.
If you've got any more suggestions I'll be more than welcome to try them out.
FWIW, I have now seen a number of de-gooped 80's non HRM dumbles, and I have never actually seen one with the 220K/3K3 and 150/2k2 values. All the ones I have seen have all been 100K/1K47 or 1K5.
I did however see those values in an HRM. Although I do use the "Hybrid" schemo, I'm definitely going to build my next non HRM with 100K/1K5 with 25uf on v1 and 5uf on v2 and I will give a full report on my results.
Funk, I saw an ungooped 80s amp, 1o4 I think, that was 220/150 on both sides! .047 midcap, 4.7 bypass across all 4 stages, 44M feedback, and a 270pf treble cap-no midboost.
There you have it.... I played it for a while as well. I like my amps a lot more fwiw.
Funkalicousgroove wrote:FWIW, I have now seen a number of de-gooped 80's non HRM dumbles, and I have never actually seen one with the 220K/3K3 and 150/2k2 values. All the ones I have seen have all been 100K/1K47 or 1K5.
I did however see those values in an HRM. Although I do use the "Hybrid" schemo, I'm definitely going to build my next non HRM with 100K/1K5 with 25uf on v1 and 5uf on v2 and I will give a full report on my results.
dogears, I guess I just misread you there, will try 180k/2,7k.
As for the bleed circuit, I actually run it on 100k or less, I just
happen to like the sound more, that's why I didn't like the 100k tail
on the pot.
Anyway I guess I should really leave the amp alone for some time
and get more hours on it before I do any more tweaking.
Hmmm.... I'd say there is something wrong if the amp needs that much "dulling" down. Maybe raise the snubbers from 270pf to 330pf??
paddes53 wrote:dogears, I guess I just misread you there, will try 180k/2,7k.
As for the bleed circuit, I actually run it on 100k or less, I just
happen to like the sound more, that's why I didn't like the 100k tail
on the pot.
Anyway I guess I should really leave the amp alone for some time
and get more hours on it before I do any more tweaking.
I finally got around to making some more changes on my hybrid a.
I put a 3,3uf parallel to the 5uf on CL2, upped the snubbers to 330p
and put the 100k tail back on the bleeder circuit.
The clarity is definately much better now and I'm getting the feeling that finally I'm getting somewhere. I also disconnected the feedback loop around CL2 and although I don't hear that much of a difference I think I'm just leaving the amp without.
Another question I have is concerning the bright cap on the global master. I think Bob-I stated in another thread that higher values (about 30 to 39p)
besides giving a little more sizzle in the high end also help to tighten the low end a bit. Currently I'm running a 12p so I guess I shall experiment a bit with different values.
Since this is only a minor change, experimenting isn't the problem, but I was wondering more about the fact that a bright cap helps to tighten the lower frequencies. Maybe somebody more knowledgeable could chime in and explain this , since I'm really eager to understand the theory behind it
Funkalicousgroove wrote:Honestly, Just Play it. I have a Joe pass/herb ellis CD that I run through my amps for about 12 hours before I ever plug a guitar in. They dont get their "tone" until around 40 hours unless you are using old seasoned trannies.
Is there some physics behind why this makes a difference? I have experienced speakers that sound better after a break in, but never imagined the same was true for a transformer.
