Getting rid off the brittle high end in BF Princeton Reverb???

[Bluefinger]

Hi,

I have built me a BF Princeton Reverb. Apart from a Deluxe Reverb OT and an added mid control it's pretty much stock. The speaker configuration I ended up wiith is 2x8". The problem I have with it (as with any BF amp) is the brittle high end. It's like I turn up the presence control on a tweed amp all the way up. I usually play tweed amps and I keep the presence control almost all the way down ... that's the way I like it. So what would be the best way to roll off these high frequencies? I already tried modifying the last gainstage before the PI to a 5F4 type with the presence controll but that only thins out the tone and adds even more high end ... any ideas?

thanks!

[riz]

Turn down the treble knob? Sorry, had to say it...

[Bluefinger]

treble and presence are two different things ... that's why there are both on many amps ...

[Jazz P Bass]

Turn down the treble knob? Sorry, had to say it...

I find anything above "3" is overkill on most older Fender amps.
The presence control is working in conjunction with the feedback loop.
The higher the setting the less feedback, which "makes" it more trebly.
So maybe if you changed the presence circuit it would help control the treble.
I have seen some Fender circuits with a high value capacitor dirrectly across the feedback resistor.
Hmmm.

[JoeM]

Did you build this as an exact BF Princeton? Try removing the 10pf cap that's in parallel with the 3.3Meg resistor. With 8" speakers you're probably getting a lot of high end.

[olddawg]

Before you do anything plug the amp into another cab like a 1x12 a 2x12 or a 2x10 cab with broken in speakers. 8s are going to be brittle no matter what you do IMHO.

[1ampman]

My friend had the same problem. He installed a 10" bass speaker and it worked perfect. I agree it DIDN'T fix the root of the problem but there are many ways of looking at tone problems. It could be your guitar, your strings, lack of bottom end to counter act the highs. Also you don't see many quality 8" speakers or many gig worthy amps using 8" speakers. A 10" would give you a lot of nice choices. Hope it all works out.....

[J M Fahey]

It has been said above in different ways, so this is no news: 8" guitar speakers will be balanced much more towards the high end plus poor low end.
Fine if you want a twangy bright Tele, but not much else.
8" speakers are excellent in a small amp where you can't physically fit anything else.
You will find much wider offer in 10" ones.
Following the Jensen line, to talk about a classic Fender speaker, an "R" will be almost what you have now, only with a little more bass; a "Q" will be milder and warmer (relatively) and Eminence makes what would be an "N" (which Jensen never made), basically a "Twin speaker" shrunk into a 10" frame , with almost the same response.
Don't remember the model name, but it's the one with an 1 1/2" VC and a heavy magnet (for a 10") say 34/38 oz or thereabouts.
I remember Weber also made something like that, it should be 10(something)150.

[JoeM]

I have a BF Princeton here for a restoration, and I have one (non Reverb) of my own. Both have 12" speakers and dont have an excessive amount of high end. Really great sounding amps.

[Bluefinger]

I am using this amp for harp mostly and I like the 2x8" configuration for studio, rehearsals and small sessions. The 8 inchers give it a trumpet like quality and fast response. The Webers that are currently in it at the moment are quite nice I guess. The amp originally had a 12" baffle board and I tried a Jensen C12K, a Cannabis Rex and a Weber 12F150 in it. They all had the same "problem". It's not a problem actually because this is what most refer to as "sparkle". I am aware that this is a quality many like in blackface amps. It's just a voicing issue that I would like to solve because the amp if perfect otherwise for it's intended use.

I will try removing that 10pF cap ... I had that in mind anyways. thanks!

[JoeM]

I was wondering if you were using the amp for harp when you stated the amp used 8"s.

[J M Fahey]

I am using this amp for harp mostly

You *might* have said so earlier, as in the post #1 instead of #10.
Oh well.
That made us all shoot in the dark.
Fine with me.

[1ampman]

You probaby need to change the tone stack. Harp tones/needs are different.

[Bruce / Mission Amps]

You *might* have said so earlier, as in the post #1 instead of #10.
Oh well.
That made us all shoot in the dark.
Fine with me.

Ha ha ha.... that kind of torpedo of omission always kills me !

[daz]

If you haven't tried the russian mullard 12AX7 RI, give it a try. It really smooths out the high end, gives it a rounder and springy sound/feel. It changes things more than most AX7's. It's done some amazing things in amps for me. I use one, but if the amp needs more than that i'll use 2 and it of course multiplies the effect. Not sure how many preamp tubes a princeton has tho, but try one....you may be pleasantly surprised.