Fine tuning/Blueprinting your amp-

[fabiomayo]

So, no HRM notes, Funk?
Thanks everyine for sharing...

[greiswig]

Non-HRM D'Lite build/tweak

#1 improvement for me was getting the voltages right at each preamp and inverter stage. I also learned that this needs to be done with several different tubes and brands in each slot, otherwise you might end up tuning the voltage for a tube that is odd, and no other tube will work properly.

#2 improvement was the Bluesmaster PI, which added some harmonic complexity that I really liked to things.

#3 is my patented "Hair" control, which really adds some extra versatility to the OD section. It basically makes the entrance to the OD trimmer continuously variable between a Bluesmaster style (great for John Mayer tones) and a standard entrance (better for Robben Ford tones).

But then I'm not done tweaking yet, because there's no goop on my boards.

[Ed de Jager]

What patent number is that exactly?

[LooseChange]

Where can I order that "Hair" control?

c'mon, let's see it.

[Zippy]

Just for clarification, Lets make sure that we specify whether we are talking about amps with or without the HRM module.. All of my notes this far are in regards to an amp without the HRM.

Excellent thread. Many thanks for this!

Thanks also to those including notes regarding what guitar (+ pickups) they are tweaking for.

[greiswig]

What patent number is that exactly?

Er..um...uh...well, it's actually PAF (patent applied for).

[briane]

well mine are not so much tweaks, as perhaps preferences....non-hrm.

1) tubes are definetly a big factor. I like to try out a ton....some just work better in that individual build.

2) I tend to prefer the .002 coupling cap on treble. I dont play a strat though, just gibson style, les paul and es335 style. I have found I prefer a mallory cap here, and on the LNFB. all rest except precense I prefer the standard orange drop. Over precense I like a solen fast.

3) rather than 68k od entrance, I like 75k. takes it down just a tad.

4) I like the 82k/100k PI, with a 10k trim.

5) I use 10k NFB to the 8 ohm tap, with a switchable 75k in series for a more aggressive sound.

6) voltages are critical, but now I have gotten so with x transformer, just always use y, and its great. I use a 500 ohm-2.7k-22k-1.5k drop string with a PT putting out about 445 VDC after rectification. I actually prefer the normal power supply to the precision, as the only precision ps build I did have no noticable difference over non-precision ps's.

7) 1k on screens. I do notice a difference with the 470 ohms, and prefer 1k.

rn65 plate and slope. carbon film throughout elsewhere. While metal film will work well, I thought my mf builds were a bit more sterile than the cf....though that could be just a case of excited expectations.

9) skyliner eq, 250k mid.

[kleinm]

Killer idea, Brandon!

I spent the better part of 6 months modifying my non-HRM D'Lite to voice it how I wanted. I posted my results a few months ago, but just for posterity here they are again.

To newcomers, these eventually became referred to as the "tweaked" D'Lite values, as seen in the layout and schematic posted here and at Brown Note. For what its worth, none of these mods are new or my own. All where taken straight from Dumble or clever and generous guys like Brandon, dogears, Gil, heisthl, Moss, Normster, Bob-I, etc.

The main differences from the “stock” D’Lite and mine are as follows:

- Bludotone 50W output transformer (talk about f***ing BALLS!)
- TAD 6L6WGC / SED 6L6GC / JAN Phillips 7581A power tubes
- EH 12AX7 throughout preamp
- 330pF treble cap (no Mid Boost switching)
- Skyliner tone stack (0.01uF/250k midrange setup)
- lowered V1B coupling cap to 0.02uF
- added 0.05uF/10M pre-OD network
- 4k7 NFB resistor off 4 Ohm tap
- 300R choke replacement resistor
- 470R screen grid resistors on 6L6s
- 3k3 swamper resistors on 6L6 (instead of 1k8)
- 220k/150k plate resistors on both V1 and V2 (with corresponding cathode resistors)
- 5uF, 10uF, 5uF, 5uF Ck’s (V1a, V1b, V2a, V2b respectively)
- 120pF bright cap
- 1k/18k/2k2 dropping string (I know it looks odd, but the voltages are just right)
- UF4007 diodes
- Bluesmaster PAB (with different padding resistor)
- 0.001uF cap across Bass pot (not 0.0012uF)
- Swapped Speaker Out and FX loop jacks so the wire routing would be neater and more Dumble-esque than with stock holes
- Dumble-style Presence wiring
- 150K post-OD2 (replaced 180K)

I'd like to point out the dropping string in my amp is odd, but it got the voltages to a place where they sounded best to my humble and meek ears.

The general idea behind these values was to carefully attenuate the bottom end entering the overdrive stages, but without ending up with an anemic sound. Other mods were done specifically to voice the midrange more to my liking, somewhat of a pronounced, fat-honk. The plate and cathode values brought a characteristic to the overdrive I fell in love with immediately. The butchered Bluesmaster PAB brought a great deal of balls to my Strat sound. It also sounds great on the OD channel with humbuckers. I don't use it much for the clean channel. The 300R choke replacement resistor cured some funky things I had at high volumes with the 500R.

Some of the mods I'm not sure what impact they had (ex - UF4007 diodes, 3k3 swampers) but I like the amp so much that I haven't touched a thing inside it since I initially posted the list. I've thought about experimenting with the dropping string...but I like the amp so much there's really no reason for me to. Time to call it "done" and move on.

With this amp and the Dumble-ator I finished last month, I'm one happy dude.

[greiswig]

- 150K post-OD2 (replaced 180K)

Man...I could hear the difference between the 1k and 500 screen resistors (less harsh with 1k), but on the resistor you're talking about here...?

I put a 1M resistor in parallel with it temporarily, and couldn't really detect much of a change. What should I be listening for?

[kleinm]

greiswig - Funk actually explains it more eloquently than I can in the first post of the thread.

4. Resistor after V2B coupler (Usually 150K) I found that 180K takes the "Edge" off but going really big makes for MUD CITY. Also, Carbon Film seems to sound best IMHO.

[greiswig]

greiswig - Funk actually explains it more eloquently than I can in the first post of the thread.

4. Resistor after V2B coupler (Usually 150K) I found that 180K takes the "Edge" off but going really big makes for MUD CITY. Also, Carbon Film seems to sound best IMHO.

Hmmm...well, one thing my amp definitely does *not* need is more edge. But I really didn't hear a difference. Interesting. Well, each amp really is a unique animal, from what I can tell.

[heisthl]

Stelligan's HRM sounded great with no resistor there (using Humbuckers) until he started playing a Strat through that amp - then putting 150K there made all the difference

[dogears]

Henry, as far as we know, there is always a 100K there. If Dave's amp had no resistor after the HRM, then it was not "accurate". 100K seems to work well fwiw.

Stelligan's HRM sounded great with no resistor there (using Humbuckers) until he started playing a Strat through that amp - then putting 150K there made all the difference

[heisthl]

I should have explained it better - Stelligan's amp had no resistor there on purpose, the original D'Lite HRM layout had no provision for a resistor on the eyelet board and at the time it was being tweaked(Humbuckers) it sounded better without one (A/B resistor/no resistor). But when I discovered he wanted the amp to be more "Strat Friendly" on the OD tonality I told him to put a coupling resistor in there and according to him, 150K made all the difference. With no resistor, his amp had more of a blues overdrive with slightly less compression, but apparently too much of an edge for a Strat. Wouldn't a 1 meg OD master 10% below spec(900K) sound the same as no coupling resistor in an HRM unless you ran the control above 8?

[Luthierwnc]

It isn't really a tweak but power tube plate volts make a big difference. You can make a good amp at any end of the range. I like higher (450-470 VDC) for the best cleans. 430-450 VDC gets you a little more blues. I'm talking full-sized 6L6's here. YMMV, Skip