Why no Baxandall in a TW?

[fusionbear]

Hello, I'm still a noob when it comes to TW's, but I was hoping someone might know why the Baxandall tone stack wasn't used by KF? Does it change the characteristics that much?

Please instruct me as always gentlemen.....

[doctord02]

I doubt you can name a rock/lead guitar voiced amp that uses a Bax stack to be honest...

In short, the Bax isnt favored in this sort of amp. A jazz or bass amp maybe, but not a full out screamer...

[stevlech]

I'm pretty sure the Carvin Legacy has such a tone stack, and along with it a reputation of being difficult to tweak. My guess would be that it would make an already touchy amp MUCH harder to dial in.

[doctord02]

Remember Ken was a service tech for Ampeg and would have been intimately familiar with Bax style tonestacks. I'd guess the decision to not use a Bax was a conscious one...

[LeftyStrat]

The imperfections of the classic MFV tone stacks are something we've become accustomed to. Grab Duncan's TSC and look at the reponses with the controls at 50 percent. The Fender stack has that low mid dip that sounds great on clean tones. Marshall dip is less and higher up.

Plug your guitar into a stereo and listen to how bland it sounds with a flat response.

Also, you can plug in the values for the Wreck tone stack into the Fender model, and see how Ken used it to voice the wreck.

The model called James in the TSC is the Bax.

[d95err]

I think Fender used the mid dip tonestack to compensate for the rather poor speakers at the time that were lacking in bass and treble response. So it might actually have been an attempt to keep a somewhat flat frequency response. (By accident, this kind of speaker prooved perfect when musicians started pushing their amps into distortion).

In high gain preamps, the mid dip also compensates for the bass and treble cut you need to keep the distortion under control.

The Trainwrecks don't really fit into any of these categories, since it's built for high gain, but has the tonestack early in the circuit. That's probably why it's such a sensitive circuit. It uses the tonestack to shape the sound before distortion, rather than as a "safeguard" to keep runaway frequencies under control. It depens on getting everything just right after the tonestack with no variable controls (except Presence).

[riscado]

actually leftyStrat, the james and the baxandall are not the same. The tone stack in the tone stack calculator is indeed the james and not the baxandall.

The baxandall circuit is active... the james is passive (most people seem to think they're the same though

[LeftyStrat]

actually leftyStrat, the james and the baxandall are not the same. The tone stack in the tone stack calculator is indeed the james and not the baxandall.

The baxandall circuit is active... the james is passive (most people seem to think they're the same though

You're right, forgot the bax was active.

The responses are similar, however, in that "flat" really means flat, unlike most guitar amp stacks.

What was the E series used in? Wasn't that used in some later model Fenders?

[riscado]

E series is called that way, due to it's use on the late tweeds (narrow panel), like the bandmaster/pro/super, it's a very primitive treble/bass tonestack and it sounds absolutely marvelous to my ears in that amp topology...

Those things used that tone stack after a cathode follower and then followed by a cathodyne inverter with an extra gain stage to make up for the fact that the cathodyne has unity gain.

Examples of the circuits it was used in are: 5E7,5E4-A,5E5-A (E-series) and 5F4, I believe it was also used in the bassman 5E6-A version.

While we are at it, there was a fender that used a James (passive baxandall) type tonestack, the Blonde twin (61-63) 6G8 circuit.

One tonestack I'd be curious to see in a trainwreck and I might eventually end up trying it in my own trainwreck (which is under construction as we speak) is a 6G4 early brown fender tonestack (the one that was labeled reverse, bass/treble/volume), those things are plate driven but have a very marshally looking frequency curve... I'd bet it would sound lovely with some tweaks...

[LeftyStrat]

One idea I've always wanted to try is to have several "fixed" tone stacks, using just resistors (or maybe trimmers) and caps based on standard tone stacks like Fender and Marshall, and then have a rotary switch to select between the different "voices", followed by something like the Bax.

So then I could select the Fender "voice" on the rotary, but still have the better control of active controls that don't interact. From a usability standpoint, it seems we use tone controls to either compensate for a guitar, or compensate for a room. So separating these functions could be useful, i.e. having two inputs that each were tuned for different guitars, and a separate set of global controls to tune for the room.

[fusionbear]

As always, thank you for your comments. I have learned so much from you all. What prompted my question is that I own a Red Iron T-Rex that sounds delicious and it has the Baxandall active tone stack. I really like the way it works. I have considered making a TW using this tone stack, but I think it would change the response too much and still be able to call it a TW....

[FUCHSAUDIO]

You're right, forgot the bax was active

Not sure if that's true. The Ampeg Gemini (as an example) has what I believe would be called a Baxandall stack, but it's passive, not active. The Rickenbacker schematic shown in my attachment shows basically the same stack, except with feedback around the tube.

The stack looks the same, but has feedback off the plate into the tone stack and back to the grid.

Technically, I believe both are considered Bax.

[FUCHSAUDIO]

You're right, forgot the bax was active

Not sure if that's true. The Ampeg Gemini (as an example) has what I believe would be called a Baxandall stack, but it's passive, not active.

The stack looks the same, but has feedback off the plate into the tone stack and back to the grid.

[jaysg]

The Ampeg V series was mostly Baxandall. Also, there's an old Orange Matamp that sounds great. I'll admit that when I had a V4, I was certainly trying to set the EQ to sound Fenderish.

[LeftyStrat]

I can't seem to find any info regarding the James tone stack, everyone seems to use the terms together.

The original Baxandall article was about using the tone stack in a negative feedback loop:

Baxandall, P.J. “Negative feedback tone control – independent variation of bass and treble without switches” Wireless World 58.10 (Oct. 1952) 402. Correction 58.11 (Nov. 1952) 444.

Duncans TSC page used to call the James the "passive predecessor to the Baxandall", but that section doesn't seem to be there anymore.

I guess convention has become to use Bax for both. Which probably makes James pretty angry.

Actually, I just found PDF's of both articles (attached). The James article is from 1948, and the Baxandall article as mentioned is from 1952. Baxandall sites the James article in the notes.

Funny thing is, if you look at the last page of the James article, someone suggests that Micheal Volkoff had actually created it in 1939. So maybe James being dropped for Baxandall is karma, we should be using the "Volkoff tone stack."