bluesmaster?

[Funkalicousgroove]

It depends on your definition of "Max clean headroom" is, In a 4 6l6 amp with twin Iron I typically get 82 watts with a standard PI, with the BM PI I typically get about 76 watts. If you can hear the difference between 76 and 82 watts I'd like to hire you!!

[dogears]

This is all crazy talk.... LOL

Just try the darn thing for yourselves..... Don't listen to anyone except your ears.

For me, the BM added lots of harmonics and air on the notes. I love it. My cleans have never been better, IMHO.....

[chris_sanford]

It would have to not compromise max clean headroom for me to favor it. There seems to be some question about this. With those values there could be more neg FB which may help keep it clean, no?

Actually, the Marsh PI setup has less NFB (100k over ~5k from the 4ohm tap), so you get some volume back, even though the Marsh PI clips sooner than the standard D-style PI.

chris

[Tonegeek]

I currently have the Bluesmaster PI/presence. This PI seems to add a little more "bite" to the sound and I agree that it delivers more harmonic complexity. While I mostly like the change, I feel like there is some not so musical breakup happening at higher volumes that was not there before the change. It sounded like a speaker with a cracked cone so I tried a cab with higher wattage speakers and it did the same thing. When playing with the band or at low to mid volumes, I do not notice the breakup, mostly just when playing loud, alone. Eventually I will switch back and decide which one to keep. My sense is the 24k PI is more transparent and the BLuesmaster PI is more colorful and may appeal more to rock players. It is after all very similar to a Marshall PI/presence circuit.

[TimS]

I currently have the Bluesmaster PI/presence. This PI seems to add a little more "bite" to the sound and I agree that it delivers more harmonic complexity. While I mostly like the change, I feel like there is some not so musical breakup happening at higher volumes that was not there before the change. It sounded like a speaker with a cracked cone so I tried a cab with higher wattage speakers and it did the same thing. When playing with the band or at low to mid volumes, I do not notice the breakup, mostly just when playing loud, alone. Eventually I will switch back and decide which one to keep. My sense is the 24k PI is more transparent and the BLuesmaster PI is more colorful and may appeal more to rock players. It is after all very similar to a Marshall PI/presence circuit.

Thanks for the report!

A few questions:

-Is it a big difference or a subtle one?

-Can you still get a nice smooth sound if desired or is the bite impossible to dial out?

-How do the cleans sound?

-What affect (if any) does the change have on the low end?

-Which PI would you say is more versatile overall?

Thanks.

[Tonegeek]

-Is it a big difference or a subtle one?

A hair more than subtle...

-Can you still get a nice smooth sound if desired or is the bite impossible to dial out?

My experience is Less bite at lower volume in OD.

-How do the cleans sound?

The cleans sounded a bit crisper to me. I needed that on my amp which was a tad dull before the change. However, I also added 47p over my clean master since then and now wonder if the old PI would sound just as good.

-What affect (if any) does the change have on the low end?

I think it did tighten it up a bit but it was very subtle. The BM PI should make a difference because that circuit uses lower value power tube grid couplers which would raise the bass roll off knee.

-Which PI would you say is more versatile overall?

Can't say, but I would reiterate what dogears said above - Try it yourself and see. He loves it and he aint called "dogears" for nothin'. It is a handful of parts and 30 minutes labor at most if the chassis is already exposed. I think this is one of those personal taste issues and would somewhat depend on what is happening upstream. If your amp and or speakers are kind of dark or dull or you need more complex harmonic overtones in the upper register, then the BM PI will perk it up some.

[TimS]

Can't say, but I would reiterate what dogears said above - Try it yourself and see.

Yeah, I'm definitely going to experiment. I'm just trying to decide which one to start with (I'm still waiting on Brownnote to ship me the correct transformer so I can build the damn thing.)

Actually, if I'm understanding this correctly, the Bluesmaster PI consists of three seperate changes to the standard Dumble PI that could be considered individually: changing the operating point of the PI tubes decreases headroom and increases breakup (and therefore harmonic content), decreasing negative feedback adds edge, and lowering the coupling caps tightens the bass.

If that is indeed the case, I wonder how a hybrid of the two PIs might sound - using the standard PI resistor values and the Bluesmaster NFB and couplers, or vice versa. There may even be a sweet spot between the standard and Bluesmaster PI setups that gives you the added harmonic complexity without the harshness.

Has anybody experimented with this? If not, I'll give it a try and post the results.

[yeahyeah]

what's the difference in runing the NFB from the 4ohm tap vs. the 8ohm?

[chris_sanford]

what's the difference in runing the NFB from the 4ohm tap vs. the 8ohm?

You get a higher feedback voltage running from the 8 ohm tap vs from the 4 ohm, thus more feedback. Use V=sqrt(P*R), where P=power (say 100 watts) and R is the load (4ohms, 8ohms, 16ohms, etc) and you will see what's happening. The 16 ohm tap provides twice the FB voltage as the 4 ohm tap.

HTH,

chris

[groovtubin]

what's the difference in runing the NFB from the 4ohm tap vs. the 8ohm?

the diff in TONE and feel is HUGE changing feedback taps, experiment fer sure!
jp@Omegaamps.com

[groovtubin]

I currently have the Bluesmaster PI/presence. This PI seems to add a little more "bite" to the sound and I agree that it delivers more harmonic complexity. While I mostly like the change, I feel like there is some not so musical breakup happening at higher volumes that was not there before the change. It sounded like a speaker with a cracked cone so I tried a cab with higher wattage speakers and it did the same thing. When playing with the band or at low to mid volumes, I do not notice the breakup, mostly just when playing loud, alone. Eventually I will switch back and decide which one to keep. My sense is the 24k PI is more transparent and the BLuesmaster PI is more colorful and may appeal more to rock players. It is after all very similar to a Marshall PI/presence circuit.

Bro! Ya GOTTA change the entire circuit, mine smokes... Tight and percussive chunk chords from heaven..

[TimS]

Bro! Ya GOTTA change the entire circuit, mine smokes... Tight and percussive chunk chords from heaven..

Do you have any clips you could share? I'm dying to hear those "tight and percussive chunk chords from heaven" - it sounds like it might be exactly what I'm looking for.

[groovtubin]

Bro! Ya GOTTA change the entire circuit, mine smokes... Tight and percussive chunk chords from heaven..

Do you have any clips you could share? I'm dying to hear those "tight and percussive chunk chords from heaven" - it sounds like it might be exactly what I'm looking for.

no clips, i could play it over phone, i use my EL-34 HRM w/band, this ones a proto..jim@Omegaamps.com

[Funkalicousgroove]

I have clips, but they are MP3 and this thing will not let me post them.

[groovtubin]

I have clips, but they are MP3 and this thing will not let me post them.

make a video, post on youtube like i did

jim@omegaamps.com