non-HRM with BM PI?

[odourboy]

I don't recall reading about anyone tyring this particular combination. Has it been done? Does it work or would it be a waste of time?

[stelligan]

Latest incarnation of this amp:
https://tubeamparchive.com/viewtopic.php?t=1620

Clip:
http://www.jonesin.org/Dave/slyMM.mp3

Like the OD - Think it hurt the cleans & headroom a tad......

[odourboy]

Thanks Stelligan! That thread slipped through the cracks because the PI was't actually discussed in the posts regarding the changes Henry did. All and all, seems like it's worth a try. Easy enough to change back to a standard PI if I'm less than thrilled.

[greiswig]

I like it in mine. Seems to add some zing to the tone that I prefer.

[toml]

I have a d'lite build that currently includes the BM PI.

I have read where others have commented about the effects the BM PI has on harmonics and bloom, but I will add a take on it that is a bit different.

Where as the original D-lite PI worked well for me when playing with a light touch, as I played harder, the tone could sometimes take on a "strident" character. To me and my playing style, the BM PI seems a bit more forgiving to a more agressive pick attack. This is particularly noticable to me when I am playing a strat.

Anyone else notice something similar?

[jspax7]

I have a d'lite build that currently includes the BM PI.

I have read where others have commented about the effects the BM PI has on harmonics and bloom, but I will add a take on it that is a bit different.

Where as the original D-lite PI worked well for me when playing with a light touch, as I played harder, the tone could sometimes take on a "strident" character. To me and my playing style, the BM PI seems a bit more forgiving to a more agressive pick attack. This is particularly noticable to me when I am playing a strat.

Anyone else notice something similar?

Yes.

Still responds to a light touch too.

[Funkalicousgroove]

I built one like that, I have to say that I don't care for it at all, to me it's gnarly sounding and REALLY bright. JMHO

[greiswig]

Having read Brandon's opinion on this, I find myself a lot more interested in other's experience. In my own build, I did the Bluesmaster PI at the same time I made some other changes, so I can't readily attribute sonic changes to only the PI.

Surely others have tried this? I know kleinm did, and a number of people (myself included) jumped on his bandwagon to make some of the same changes. From his "Unintentional Manifesto" post:

I previously had the Bluesmaster PI and Presence circuit, but I decided to start with the “standard” Dumble PI in this. I’m still on the fence as to which I like more. The BM is certainly more complex and adds both crazy harmonics and crazy bloom. The “standard” is noticeably smoother and seems to stay more consistent across different volume situations. Each has their strong points….

I also used to have a treble bleed network because the amp was pretty bright, borderline nasal/harsh before. I decided to start without it and take it from there.

When I fired it up the first time, I was simply shocked. My amp NEVER sounded this good before. Its well-balanced, and never harsh. It has great high-end, but isn’t harsh like it could get before. This amp now needs no Band-Aids, which is something the amp had an abundance of before. The only change I plan on doing is making the LNFB switchable on V1B, which is why the empty DPDT is in the rear corner.

Given Brandon's comment and kleinm's comments above, perhaps some of the people who walked away looking for a treble bleed for the OD channel in particular had also changed to a BM PI?

[heisthl]

I took it out of every build I put it in because of less clean headroom.

[greiswig]

Well, I took mine out this evening because I felt like it: I was curious.

For one thing, the amp is louder with the standard PI. Notes have a harder impact, and the amp feels less spongy. It also seems to be easier to get feedback.

The Bluesmaster PI had more "bloom" around the notes, which was definitely nice. The standard PI isn't as bright, but the treble knob only needs a couple of ticks up to sound very similar tonally.

I notice that the PI plate voltage jumped up 20V with the standard PI.

[stelligan]

I took it out of every build I put it in because of less clean headroom.

I definitely liked the cleans better before and they are very important to me on a gig. This Music Man is so nice and small - and loud, but the chassis is such a tight squeeze that it is a pain to tinker with. I have only left this amp alone because I have too many soldering irons in the fire. The next time I open up this amp it will be to:
1) Convert it to EL34
2) Add foot switching to the mid boost
3) Yank out the BM PI

[Structo]

Forgive me if this is redundant but what exactly defines a BM PI?
I was looking at a D'Lite BM schematic and it shows 100k/110k plate resistors with 47pf caps in parallel.
That was the only difference that jumped out at me.

[greiswig]

Forgive me if this is redundant but what exactly defines a BM PI?
I was looking at a D'Lite BM schematic and it shows 100k/110k plate resistors with 47pf caps in parallel.
That was the only difference that jumped out at me.

IIRC, there are four resistors that change, along with two caps. The presence control changes, too. Take a closer look.

[toml]

I actually want less headroom.

The type of cleans I am looking for are the cleans that have a little hair on them. They sound clean with volume rolled back/lighter touch, but get a little dirty when playing with a heavier touch.

With my Tele and Strat style guitars, I found in my initial build with standard PI that I was never fully satisfied in obtaining this style of clean.

Funk, on your build, did you keep the BM and address the gnarly and bright tone or did you rewire to the standard PI?

If you kept the BM, any mods that addressed your disappointments beyond those in your "blueprinting" thread?

[heisthl]

I actually want less headroom.

The type of cleans I am looking for are the cleans that have a little hair on them. They sound clean with volume rolled back/lighter touch, but get a little dirty when playing with a heavier touch.

Change V1a to 100k plate(Rp) 1k5 cathode (Rk) with a 10uF to 25uF bypass cap (I like 25uF) , put in a .047 (or.05) mid cap and leave everything else the same. Run the preamp volume above 4.