Tone control in Tweed Princeton 5F2-A Clone

[cathode]

I just build my first amp: a princeton 5F2-A clone from the Angela Instruments homepage. Following link gives you a schematic view:
http://www.angela.com/catalog/how-to/single_6v6/princetonsch.gif

Well, the project was easy to do. I put the chassis into an old Fender Bronco cabinet (Tweed!) and used a Weber 8-SigA-S4 speaker. The amp is a little eye catcher and only humming a little bit at highest volume levels (it's o.k. for me).

My problem is that following the Angela Instruments schematic the amp sounds really muffy. 'Angela' changed the 1M tone pot into 250k and this is the main reason for the muffy sound I think. (s.o. Brian Newman's threads)

Because of the sound I did two modifications:
a) I took out the tone stack and let it run as a '5F1 Champ'...
No solution - the amp doesn't sound much better. I still miss the treble frequencies (perhaps the speaker....?!?)
b) Because I just had a handful parts left and second 250k pot (and no 1M one) I modified the tonestack into a Brownface Tone Control with Bass and Treble pot
Much better! This is something to work (control) with! But the amp isn't as loud as before and this can't be the end of the line...

My questions: has anybody an idea for an usable tone stack with Bass and Treble pot that doesn't take so much signal level?
Is tone control first and volume control second the right order to save the best 'information' from the guitar signal?

Looking forward for some output (HEELLPPP!!) of your stock of knowledge

Carsten

[cathode]

Probably I did a mistake by connecting the volume stack and the tone stack together without a capacitor inbetween for decoupling the two circuits ?!?
I will check it out this evening...:confused:

But there is still the question if I have to install the tone stack first for a better quality...

Carsten

[MWJB]

Why not go back to the tone pot but at 1meg. A bass control is a good idea with bigger amps for paring off thuddy lows, that shouldn't be necessary with a 5F2A with a 6V6.

You're a bit limited as far as T(M)B tonestacks go as you only have 2x12AX7 triodes to play with, losses are pretty well inevitable. With another preamp tube you could go for a tweed style tonestack.

[cathode]

try the basic tone control with the 1 Meg pot is another opportunity I'd like to test out, but for this I have to order another 1 meg pot.

Anyway, in my circuit the 1 meg volume pot is directly in parallel to the 100k resistant and the 250k bass pot of the browneface tone control. The result is a big missmatch of the bass control and less volume output. I'm sure I can fix it with an input capacitor of 0.022uF in front of the tone stack.

I'll give you the results later...

[cathode]

Here we are with the results:

with that extra 0.022uF capacitor between volume and tone circuit the influences between the pots is gone. The volume losses decreased but are still well recognized, especially with a stratocaster. Playing an Epiphone Emperor (humbuckers) or an '67 Gretsch Nashville (filtertron) the volume is o.k. to me.

MWJB was right: for this brownface tonestack the amp needs another preamp tube. Otherwise it won't fit!

Now I'll order the 1 meg tone pot...

[Satamax]

Hi Carsten, in the mean time if you want to play, you could fit 470KΩ resistor between your 250K and ground. If still too bassy try 680, or more.