Dumble versus Blue Master PI stage in D'Lite?

[Mark]

I was wonder what the differences in tone are between these two PI stages. What does each PI stage bring to the party?

https://tubeamparchive.com/viewtopic.php?t=7572

I believe the above thread does mention the BM PI is the preferred one and the clean sounds are enhanced, but there is more to be said on the matter, such as how much eq do the presence control provide etc?

Is the gain roughly the same etc?

Thanks.

[Normster]

I was wonder what the differences in tone are between these two PI stages. What does each PI stage bring to the party?

https://tubeamparchive.com/viewtopic.php?t=7572

I believe the above thread does mention the BM PI is the preferred one and the clean sounds are enhanced, but there is more to be said on the matter, such as how much eq do the presence control provide etc?

Is the gain roughly the same etc?

Thanks.

I wish I could answer that, but I've only used the BM PI in full BM builds. (No hybrids so far.) I think Moss has said that the PI breaks up sooner with the BM PI and is also livelier since there's less NFB.

[brownnote]

I'd say the BM PI has more grit and is more lively with top end shimmer, it will definitely decrease your clean headroom, but you will get a nice warm breakup in the clean channel.

The standard PI is stiffer, more headroom, seems to have more harmonics, more aggressive when it breaks up.

YMMV

[Mark]

Dear Normster and Moss

Thanks for the reply. I thought that the PI stage had to have more gain.

That reply does challenge my theory on using a D style amp. I always thought the amp is to stay "clean" and the distorted tones are purely derived from the overdrive pre-amp stage. Interesting!

Just out of curiosity do you have any personal preferences Moss?

[Structo]

Having a D'Lite 44 with 6L6 I can definitely say it is not an amp with huge headroom.
But it's the kind I like.
Once you get pretty loud you are into power tube distortion.
I don't really have a BM PI, I have the higher plated at 120k/110k but the rest is pretty standard.

I would not want it to break up any earlier.

[Mark]

Dear Structo

I usually have the master volume set to about the 9:00 position and the OD level is at about 7:30. (The volume and the OD gain controls are around 1:30 and the internal trim is set to 11:00).

I find this has the distorted tones a bit louder than the clean tones. Headroom hasn't really been an issue or perhaps I'm not running anything in the effects loop to hear a lack of headroom.
I'm usually aware of output tube distortion, but I've always assume this isn't what the Dumble is about as people have expensive effects processors in the effects loops of these amps.

Is there something that I am missing with these amps?

I have chosen to edit my post as I have given the amp a run with a bit of volume tonight (9th of Feb 09.) The amp sounded the best I've heard it!

The controls were set at volume 1:30 to 2:00, treble 10:00, mids up full, bass at 3:00, both the overdrive gain and level were set at 10:00 to 11:00 and the master and presence control were set at 9:30 to 10:30.

The clean tone was showing some signs of distortion but in a very pleasant way. The overdrive tones were great! (I'd even say huge, but one man's huge is....)

It did make me wonder if the distortion through the PI and output stage would comprise the effectiveness of the effects loop?

How do people get the big tones and have the effects loop working for them?

(Yes there are always more questions from me )

[Structo]

Which amp do you have Mark?

What speakers are you running it through?

[Mark]

Dear Structo

The guitar was a PRS 24 custom (I think a good Les Paul would have sounded fatter, but the PRS covers a lot of ground.)

The amp is more or less a ODE 33, and the speaker used is a Mesa Boogie Celestion 90. It was all stuff I had on hand. Needless to say I am still quite pleased with the tone.

[Structo]

So is this a scratch build but based on the D'Lite circuit?

It can be finicky to get the tone shaped as you want that's for sure.

I find that you have to really experiment with the knob settings on these amps to get the most out of them, particularly the volume and master.

So are you running 6V6 power tubes?

[Mark]

I was looking at a circuit of the BM PI and I thought of people saying it lacks headroom.

The circuit does look a lot like the 60's Fender PI stages bar the 470/510 ohm cathode resistor. Perhaps the 820 ohm resistor that was originally used in the 6G series Fender amps might be the trick, or perhaps using a 12AT7 etc?

Just a thought.

[heisthl]

I've done a lot of experimentation on the 12AT7 PI and it does have more headroom but the character of its distortion is not quite as pleasing and the overtones dont' have the "random" extra amount of character like a good 12ax7 PI can give you.

[Structo]

The 820R is the stock value for the D'Lite with the 24K tail.

[Mark]

Yes that is true, but it could also be used as a replacement to the 470 ohm to lower the gain of the PI.