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What is "BF fixed mid" tone stack?

greiswig

Power User
I know, I know...if it sounds good it is good.

I'd still like to know: what is this based on, and what does it mean?

I can't seem to find a section of the wiki that describes the actual tone stacks. It would be really nice to see that list, and also what frequency they are supposed to default to and where in the preamp chain they were designed to fall, and maybe also things like what bright cap they came with.
 

Rotti

Fractal Fanatic
Wild guess here, but I would imagine "BF" is "Blackface," as in some pre-CBS Fender amps.
 

greiswig

Power User
Well, I was assuming that it meant either blackface or brownface, but it would be nice to know which. But also what the "fixed mid" part of the equation is.

I could imagine a tone stack that had only bass and treble knobs, with a fixed R value for the midrange...but I don't know.
 

greiswig

Power User
A Deluxe Reverb, for example, has no Mid pot but a fixed resistor. The value of that resistor is 6.8K. If you use a "Fixed Mid" tone stack the value of the virtual resistor will be 6.8K when the Mid control is at noon.
Thanks! So is the midrange control disabled in the AxeFX? I ask because on some of the ODS amps that are modeled on preamp boost (which is really a bypass of most of the tone stack), the controls still seem to work, where on a real amp they don't when PAB is engaged, IIRC.

And so this stack is based off a blackface Deluxe Reverb and would be the default for that amp model?
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
Thanks! So is the midrange control disabled in the AxeFX? I ask because on some of the ODS amps that are modeled on preamp boost (which is really a bypass of most of the tone stack), the controls still seem to work, where on a real amp they don't when PAB is engaged, IIRC.

And so this stack is based off a blackface Deluxe Reverb and would be the default for that amp model?
If you use a "Fixed Mid" tone stack the value of the virtual resistor will be 6.8K when the Mid control is at noon.
 

Wolfenstein98k

Power User
Great info here, thanks all.

I was wondering, the Tonestack is an interesting if unfamiliar beast. Maybe in the Wiki, could there be a breakdown of the Tonestacks and their characteristics, similar to what has been done with the Drive block in the Wiki? That is massively helpful, with even a basic tonal description of each of the drive types, etc.
 

jefferski

Fractal Fanatic
Great info here, thanks all.

I was wondering, the Tonestack is an interesting if unfamiliar beast. Maybe in the Wiki, could there be a breakdown of the Tonestacks and their characteristics, similar to what has been done with the Drive block in the Wiki? That is massively helpful, with even a basic tonal description of each of the drive types, etc.
I'd love to see this!
 

Thomas Larsson

Experienced
Thanks! So is the midrange control disabled in the AxeFX? I ask because on some of the ODS amps that are modeled on preamp boost (which is really a bypass of most of the tone stack), the controls still seem to work, where on a real amp they don't when PAB is engaged, IIRC.

And so this stack is based off a blackface Deluxe Reverb and would be the default for that amp model?
I think on those ODS models the pre-distortion tone stack doesn´t work, but the AXE has another, post tone-stack, added to the circuit, that of course does work .
 

greiswig

Power User
Another...vaguely related tone stack question: According to the wiki, the Ford ODS amps are based on a non-HRM model, but it doesn't say what tone stack that amp had. Should I assume because of the mid frequency that it uses the Classic tone stack?

EDIT: maybe not...there is no such stack in the list. So...?
 
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Thomas Larsson

Experienced
Another...vaguely related tone stack question: According to the wiki, the Ford ODS amps are based on a non-HRM model, but it doesn't say what tone stack that amp had. Should I assume because of the mid frequency that it uses the Classic tone stack?

EDIT: maybe not...there is no such stack in the list. So...?
I think they call it skyline but I´m not shure. The dumbles also have lots of switches for jazz - rock etc so there should be several skyline models . On the other hand I think they look like blackface stacks in rock position, but I´m not 100% shure of that ...
 

greiswig

Power User
I think they call it skyline but I´m not shure. The dumbles also have lots of switches for jazz - rock etc so there should be several skyline models . On the other hand I think they look like blackface stacks in rock position, but I´m not 100% shure of that ...
Not quite what I'm asking, and I'm hoping Cliff will weigh in. Earlier models had what is known as the Classic stack, which IIRC was somewhat like a modified Fender Twin stack. That mid control was centered right around 650Hz, but would be tailored to the buyer. Later models incorporated the Skyliner stack, which was centered around 400Hz. The HRM stack was actually a secondary fixed tone stack internal to the amp that applied only to the overdrive channel.

Both Skyliner and HRM stacks are in the list of the tone stacks, but I didn't see Classic in there. So I'm trying to find out if any of the Dumble variants use the Classic stack?
 

FractalAudio

Administrator
Fractal Audio Systems
Moderator
All the Dumble models either use the Skyliner tone stack in a pre configuration or no pre tone stack with an HRM tone stack post. The latter being the classic preamp bypass (PAB) setting.
 

greiswig

Power User
Thanks, Cliff! Let me know if you ever want my Classic non-HRM KT-90 beast to model. I think she sounds pretty darn good. Definitely a different flavor from the Skyliner circuit. I know these aren't really your thing, but the offer's there.

I'm actually finding some of that Classic vibe using a couple of the other Fender stacks with altered mid frequencies, but I haven't really spent too much time on that yet. But this, I think, helps me explain some of the fight that I'm having with the existing ODS models: all of them are Skyliners or HRM's.
 

api4u

Experienced
All the Dumble models either use the Skyliner tone stack in a pre configuration or no pre tone stack with an HRM tone stack post. The latter being the classic preamp bypass (PAB) setting.
Cliff,
Dumb question here.... so does this mean the D* models already "have" the Skyliner tone stack, if you select the default "Tonestack Type", or that you will get a more realistic, authentic tone, if you select the Skyliner, in the "Tonestack Type". This is a niggling concept I've never quite settled in on, in my own mind....
 

Thomas Larsson

Experienced
Cliff,
Dumb question here.... so does this mean the D* models already "have" the Skyliner tone stack, if you select the default "Tonestack Type", or that you will get a more realistic, authentic tone, if you select the Skyliner, in the "Tonestack Type". This is a niggling concept I've never quite settled in on, in my own mind....
Like Cliff said, all of the default stacks are skyline (pre or post). If you are insecure, switch from default to skyline, and listen for any diferrence. I don´t think you will find one.
 

Rex

Legend!
so does this mean the D* models already "have" the Skyliner tone stack, if you select the default "Tonestack Type"...
Yes. When you set the Tone Stack Type to DEFAULT on any amp model, you get the "correct" tone stack for that model.
 

greiswig

Power User
Like Cliff said, all of the default stacks are skyline (pre or post). If you are insecure, switch from default to skyline, and listen for any diferrence. I don´t think you will find one.
That's not my understanding, if I read you right. Some of them use the Skyliner stack, in the pre position. I think one giveaway here would be the 400Hz frequency of the stack, since that mirrors my understanding of the Skyliner circuit. But the HRM amps have the Rumble HRM stack set in the post position, with a 650Hz frequency.

As for api4u's question about defaults, think of default as the way of picking from one of the other tone stacks in the list. That's why I was noting that I hadn't seen Classic a an option, so I figured it wasn't there. This is also why in one of my wish list requests, I'd just asked that instead of saying "default" in the menu option, it would have a treatment like Skyliner* ...put an asterisk next to what the default value actually is. If that same treatment were applied to other parameters, it might be really helpful.
 
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