I am in the process of reading all 52 pages about the OTS, HRM's and the many versions.

I have noticed that mods from forum members have been offered and it seems to improve the amps.

I don't do my own wiring but when I order the amp, I would like it to have the necessary mods/upgrades so that I don't have to keep running to a tech every week.

So far I favor an HRM Skyliner II but unsure if it should be a 50 or 100.


These are the mods that I have seen so far, and would like anyone's opinion as to whether these should be done to the amp from the start by Nik, please.

use a 1n capacitor in series with a 150k resistor soldered to OD master pot in and ground. This trims off the fizzy highs in my HRM amp.

would adding a treble bleeder after the HRM tone stack smooth out the treble

power scaling?

LNFB mod. (lift negative feedback) toggle switch? What does this do?

Get the cathode bypass switch installed to explore the saggy side with less fuss

What will this mod do? Change the slope resistor from 150K to 82K; I removed the 22pF snubber from V2a and I increased the snubber on V2b to 700pF to end fizziness.
 
What is "resistor with choke switch mode" on HRM?
 
Can variable pot or three way toggle be added to amp to tame the bypassed second channel
EQ and maintain equal volumes when the tone stack is bypassed on second channel of HRM?
 
Can the amp be made to have power tube saturation if desired?

Before I email Nik, since these mods came from forum embers, I was interested to know if I should add these to a build from Nik.

Also, would some of these mods only need to be done on an OTS, rather then an HRM?

Thank you to the forum for any help you might be able to offer.  I am really confused and frustrated by everything involved with these amps so far.  I just don't know where to begin.

I don't know much about the HRM MkII, but I know that my Bluesmaster can saturate the power section, and depending on the tubes i have in there, can sound damn awesome doing it. The BM is a good candidate for Power Section saturation, due to the design of the PI. Sometimes i actually use the Normal channel as an overdrive channel (preamp volume and master dimed), and the OD channel as a clean channel by backing off the drive.

On mine the HRM tonestack is disconnected, and i haven't put a different resistor on mine to work on the volume jump yet, but i will soon.

Power scaling has been done on the OTS series, but the OTS actually has a very good and effective master volume system that doesn't suck tone very much, and if you use  a c-lator as a global master volume, it really eliminates the need for power scaling.

Switchable Fixed/Cathode Bias was something i was toying around with, and i think a few guys have added it to their rigs. My reasoning for doing it was two fold.
1) Financial. I wanted to have both a fixed and cathode biased amp in one.
2) I like to see if i can do things
in the end i decided it wasn't worth the hassle, and the real estate inside the OTS is kinda tight, so that project went by the way side.

The only mods i have on mine, besides the bypassed HRM stack are:

1)Half power switch (Pentode/Triode on 50 watters like mine)
2)Sag Resistor switch, a switch which places a switchable resistor on the center HT Tap to lower the HT voltage down and simulate the sag that comes from having a tube rectifier (common mod on amps with ss rectifiers)
3)A Mega PAB switch which switches the resistor connected to ground on the PAB circuit to allow for alot more gain. This is either very useful or completely worthless, depending on the situation, believe it or not. I usually leave it on the stock value unless i want a very dramatic sound change.

All that being said, it is very possible that you could play through the stock amp and be completely satisfied with it.

As far a what Nik will do, the best way to find out is to email him.

Hope this helps!

Gregg