Tone Control

[CircuitButcher]

Stumbled upon (Freddie King style) a boutique amp thread (GP or other?) and came across a builder or two I hadn't heard of (not unusual with new ones cropping up almost daily).

After listening to the Teixeira amps clips it was apparent (slow on the uptake) that EQ for many is about finding your "spot" with an amplifier (set & forget) and that responsiveness & touch sensitivity is what the fingers & ears search for.

Accepting this (or not), can the single knob tonestack control format "float your boat" and if so, which circuit delivers the goods for you?

[BTF]

Several years ago I was given and subsequently reworked a very nice Allied/Knight 2-6L6 PA amp into a hybrid JTM45 with volume, tone and presence. I've been using this for a while as my rack's power amp and love it for that duty- I think it performs better as a power amp than any of my Fenders. Its tone control is an unusual dual-pot (on one shaft) affair. One pot is the usual treble cut while the other pot acts as a variable resistor in concert with a cathode bypass cap in the preamp's second recovery stage. You can therefore boost the high frequency gain or cut the high frequencies. It works beautifully for controlling the "bite" in my rack preamps (which have full tone stacks in each). If I were to build a one-tone control amp, I would go that route.

Salutations! BTF.

[billyz]

"single knob tonestacks" have the purist tone and response you can get short of no tone control all. Just look (listen) to a late 50's Tweed Deluxe.
Almost perfect balance of tone , if you have an very bright guitar like a telecaster roll it off , a les paul crank it it on. There is very little loss with a passive rolloff like this.

http://www.schematicheaven.com/fenderam ... _schem.pdf

[BTF]

I had a Kalamazoo 2 with a similar tone control. I absolutely loved paying that amp! No futzing with bass, mid, treble. Just take out the sharp edge and play!

[Gaz]

My favorite is in the DR. Z Maz, where the tone knob is just the AC30 hi-cut. The amp is designed so the noon setting feels pretty balanced.

[orrong65]

Absolutely right billyz.

I have just finished restoring my 51 5B3 Deluxe, and there is really no volume loss or tone scooping at any point on the tone pot, its just a broad treble-bass range at constant signal volume. And it has the ability to brighten any tone up just by dialling it further towards 9.

I like the tweed and the marshall tone stacks with the small slope resistor that seem to minimize the mids loss much more than in the blackface stacks.

To prove the point, I have just retro-fitted a tweed tone circuit (like 5F8 Twin) into the unused normal channel of my 1980 Fender 30. It totally transforms the channel, with more gain and more mids.

I now have a typical blackface bright channel, and a tweed, bluesy normal channel with bright switch as well. Great combination

[AllenBradley]

I beat off to my friend's '58 tweed Princeton every time I hear it!! It's basically a tweed champ with a single tone control added, and installed in a slightly larger cabinet. Quite possibly the best sounding amplifier I have ever heard in my life. It's still completely original. I've heard that Garcia used the tweed princeton for most of his studio work...

[Andy Le Blanc]

sticky fingers huh.....

The big difference between simple controls and TMB controls is the impedance.

The pre amp will respond differently, and the mid carve typical of TMB wont be there.
The one knob control (not a pun) is a brite pass over the vol. and treble bleed on the other side.
It plays well with a pentode stage and wont show the same loss as a TMB.