Take this for what it's worth, as (IMHO) I leaned the hard way by doing everything else but.

For BLOOM, the plate voltages need to be right
I believe the recommended values are:
V1@190
V2@200
PI @300

but you may find that others also work.

You mean mine statement or the one from ODME?
 

If it's mine,... obviously BM HRM plate voltages are different compared to OTS or OTS HRM.

Different plate resistor values, different dropping string as well - that's why different voltages.
BM amp has also different tonestak and PI section as well,... obviously all that equals to different sounding amp
 

Umm... if you don't know what I'm taking about then shouldn't you also not know what Mcinku is talking about?



In the event you mean you don't even understand the concept of adjusting the pate voltages, then it is this:
[Someone please correct me if I am wrong].
The power supply generates a high voltage that is successively dropped through string of resistors in series - and the voltages that go to the plate resistors come off the taps (B3, B4, B5) between those resistors. The values of those resistors are supposed to be selected so as to drop the voltage to the desired level. But that apparently doesn't always happen. Either that or people have determined that the noted voltages produce the best tones etc.

On my HRM, that is modded more towards an OTS, the voltages were much higher than those 'golden' voltages I mentioned. I didn't have enough 2 watt resistors to totally adjust the entire voltage divider string - so I just raised the first 3.3k resistor [delivering the B3 voltage to the PI phase inverter tubes] by adding 2.7K which lowered B3 to 300 volts at the PI tube plate. My B4 voltage was still a bit high at 210 and my B5 voltage a bit low at 183; but the amp sounded much better.

Checking the plate voltages also allows you to see how balanced your tubes are. If they are not, then the voltages can be quite disparate.

Hope this clarifies.

I'm not too sure either but from what I can gather, the plate voltages on the OTS are on the high side compared to 'established standards' whatever they may be. The dropping string resistor values used in OTS are different to those listed in other schematics that are listed elsewhere. Many people increase the 3.3K resitor to lower the plate voltage downstream. The different plate values on a 220/150 design will vary the actual plate voltage on each triode. As these are 1% tolerance resistors I'm not aware of many people adjusting these.Hywell I wouldn't have thought that lower plate voltages would give you the Matt Schofield type sound that you like? Much more likely to end up in Robben Ford territory?

Hywell, there is definitely evidence to suggest that lower plate voltages = smoother OD but my take is that this is likely to introduce even more compression into what is already quite a compressed OD tone - there again I could be wrong. If I were going to make changes to the OTS, I think I'd go down the route of changing it to a straight 100K configuration. This is another 'classic' version of a D-Style amp and some of the TR's are based around it. I agree that the OTS has a spikey top end but I find that it is a perfect match for my Telecaster that has a HB type pickup in the bridge.(DiMarzio Chopper T). I have the treble control on the amp set at 3.5 and still roll off more via the Guitar Tone Pot. But I have to say that I can get some fantastic expressive / woody tones out of it like this. Increasing the snubbers on V2 is the other option for taming treble content or increasing the grid resistors on V2a and V2b which will give a low pass filtering effect.I can recommend the book "Designing Tube Preamps for Guitar & Bass" book by Merlin Blencowe - do a google search on "Valve Wizard" and you should find the website which is almost as good as the book.