I'm trying to choose a tone stack for a guitar amp. I am inexperienced w/ guitar, and have only one one commercial guitar amp for comparison.
So, I'm basically wondering, what looks good for guitar tone controls, in the attached image?
Top row is w/out a source follower. Bottom row is with follower.
Left to right are the three different circuits I've tried. Left is the 'route 66' tone stack, which is well regarded.. But from the looks of it, it's not all that interesting.. Plus it is high heavy. And actually, w/ the follower, they're all high heavy.
But, maybe that's what I want in a guitar amp, since I can filter the highs directly at the guitar.
Any opinions?
So, I'm basically wondering, what looks good for guitar tone controls, in the attached image?
Top row is w/out a source follower. Bottom row is with follower.
Left to right are the three different circuits I've tried. Left is the 'route 66' tone stack, which is well regarded.. But from the looks of it, it's not all that interesting.. Plus it is high heavy. And actually, w/ the follower, they're all high heavy.
But, maybe that's what I want in a guitar amp, since I can filter the highs directly at the guitar.
Any opinions?
Attachments
Whole amp, minus speakers... Those measurements are at the output transformer on my model.
I agree w/ Malcolm that the top right looks the best, but it's also the most lossy.
I like the higher gain of the cathode follower version, but it's top heavy. But like I mentioned before, maybe that's ok since I can roll off the top end at the guitar.. I'm not sure what guitarists usually like.
Right now the amp has got the top left, route 66 tone stack.. I'm not impressed.
(the reason I went w/ the route 66 tone stack, is my amp has an ef86 input stage, like the route66)
I agree w/ Malcolm that the top right looks the best, but it's also the most lossy.
I like the higher gain of the cathode follower version, but it's top heavy. But like I mentioned before, maybe that's ok since I can roll off the top end at the guitar.. I'm not sure what guitarists usually like.
Right now the amp has got the top left, route 66 tone stack.. I'm not impressed.
(the reason I went w/ the route 66 tone stack, is my amp has an ef86 input stage, like the route66)
It's kind of hard to know what voicing you prefer or like to use in a live situation. One thing maybe worth mentioning is the 'look' of a frequency plot and what you'll hear in the realized amp. Go for what your ears like, not your eyes. (I.e. I take it you know you can use wav-files as input in LTSPICE, then put out a wav file.)
If you don't wanna tinker with LTspcie any more build amp with the stack that gives you the biggest ranges regarding attenuation. Then you probably be able to find some sweet spots due to the fact that the alternatives are so plentiful.
The tone-stack that caught my eyes was the middle one in the lower row. It looks a little bit like the AB763 tone-stack. Well, my ears has got a thing for that tone-stack...
Would you mind posting the schematic?
Cheers!
If you don't wanna tinker with LTspcie any more build amp with the stack that gives you the biggest ranges regarding attenuation. Then you probably be able to find some sweet spots due to the fact that the alternatives are so plentiful.
The tone-stack that caught my eyes was the middle one in the lower row. It looks a little bit like the AB763 tone-stack. Well, my ears has got a thing for that tone-stack...
Would you mind posting the schematic?
Cheers!
I can't take any credit for it.. It's the 'bone ray' tone stack. Google for more info.
(Everything from (and including) the lnd150 to the last pot, labeled u8 in my schematic. Plot above this one, top middle in the pic in my first post, is the same tone stack w/out the lnd150)
Attachments
Never hear of that tone stack. Seem a bit elaborate to throw in a FET in a tube amplifier... Ever consider going all tube? If you like to I can help you out with an all tube schematic (in LTspice).
Further, if you're not satisfied with the tone stack have a look at the 'tone stack calculator' Download. It's a simple way of getting inspired as they have multiple tone stacks presented in the soft ware.
Further, if you're not satisfied with the tone stack have a look at the 'tone stack calculator' Download. It's a simple way of getting inspired as they have multiple tone stacks presented in the soft ware.
Actually, couldn't be easier! only 2 parts.. the fet, and a resistor. No heat, no hole in the chassis. Using a tube would have been much more complex. It's a great way to quickly add a follower to any tube circuit. They're practically transparent, when used as followers, so no "sand sound" to worry about.
And yes, I did consider all tube, but I have limited space in the chassis I'm planning to use. (and I already have all the tubes I'm using.. This is a 0 cost project, just for fun)
I did consider all the usual tone stacks, but narrowed it down to these three.
I initially used the top left one, because it comes from an amp very similar to what I've built.. But, i'm not happy w/ it.. Then I tried all the usual ones, in duncan TSD. But, I don't like the lack of flat response in the traditional stacks. The baxandall is too lossy, but otherwise would have been a contender.
Thanks,
That's the sort of info I'm looking for. There aren't a lot of frequency plots of complete guitar amps, out on the webs.. (which is sort of strange.. Flat plot after flat plot of HIFI amps, which is pretty pointless and just engineers bragging.. Then for guitar where they're all probably vastly different, there's no info)
I do have a 'bright cap' across my volume, in some of those circuits.. The non follower ones all have one. I took it out on some of the follower options, because then the frequency response was about a 45 degree angle from low to high.
That's the sort of info I'm looking for. There aren't a lot of frequency plots of complete guitar amps, out on the webs.. (which is sort of strange.. Flat plot after flat plot of HIFI amps, which is pretty pointless and just engineers bragging.. Then for guitar where they're all probably vastly different, there's no info)
I do have a 'bright cap' across my volume, in some of those circuits.. The non follower ones all have one. I took it out on some of the follower options, because then the frequency response was about a 45 degree angle from low to high.
If you're looking for any overdrive from the amp then you are interested in frequency responses both before and after any distorting stages.
These will need different concepts of processing: Before you most likely need to reduce low end response because if you have too much of it all clipping just sounds like farts and you have no "note separation" to speak of. If you don't reduce higher end response radically after distorting stages all clipping will sound like someone is stuffing glass shards into your ears.
And that just some basics, the tone will vary greatly from other processing, but you need to keep in mind that EQing before or after a distorting stage affects differently and sounds different too. Rolling down bass before distortion sounds entirely different than rolling down bass after distortion, even if the frequency response plot would look identical in both cases.
Given that tone of distortion varies greatly from both pre and post equalising (while both will also different effects to end tone) it becomes apparent that where you place the tonestack in this regard will also have huge effect in both tone and overall functionality of that stack.
No, not really. Largely due to fact that a single plot of frequency response is virtually meaningless for an amp that gets deliberately overdriven.
Me neither. As a matter of fact, I prefer predictable and consistent operation of the stack. Something you can achieve with e.g. Baxandall/James tone controil but not with that mid scooping atrocity where every knob seems to interact with each other and adjustment is never consistent. Flat response of a stack... Big deal: If you prefer mid-scooped response it takes four components to introduce that externally. No one says mid-scooping (or any deviation from flat response) has to originate in the tone stack.
The name Baxandall actually refers to an active circuit. That one usually has the mid "flat" point set to +/- 0 dB. So all losses are compensated by the active circuitry. Passive form is known as "James" circuit. Calling the passive circuit Baxandall is common but incorrect. The passive circuit is naturally quite lossy because the greater the losses the greater the range for adjustment (in this case only peaks in response are close to 0 dB line).
These will need different concepts of processing: Before you most likely need to reduce low end response because if you have too much of it all clipping just sounds like farts and you have no "note separation" to speak of. If you don't reduce higher end response radically after distorting stages all clipping will sound like someone is stuffing glass shards into your ears.
And that just some basics, the tone will vary greatly from other processing, but you need to keep in mind that EQing before or after a distorting stage affects differently and sounds different too. Rolling down bass before distortion sounds entirely different than rolling down bass after distortion, even if the frequency response plot would look identical in both cases.
Given that tone of distortion varies greatly from both pre and post equalising (while both will also different effects to end tone) it becomes apparent that where you place the tonestack in this regard will also have huge effect in both tone and overall functionality of that stack.
No, not really. Largely due to fact that a single plot of frequency response is virtually meaningless for an amp that gets deliberately overdriven.
Me neither. As a matter of fact, I prefer predictable and consistent operation of the stack. Something you can achieve with e.g. Baxandall/James tone controil but not with that mid scooping atrocity where every knob seems to interact with each other and adjustment is never consistent. Flat response of a stack... Big deal: If you prefer mid-scooped response it takes four components to introduce that externally. No one says mid-scooping (or any deviation from flat response) has to originate in the tone stack.
The name Baxandall actually refers to an active circuit. That one usually has the mid "flat" point set to +/- 0 dB. So all losses are compensated by the active circuitry. Passive form is known as "James" circuit. Calling the passive circuit Baxandall is common but incorrect. The passive circuit is naturally quite lossy because the greater the losses the greater the range for adjustment (in this case only peaks in response are close to 0 dB line).
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Thanks a lot for all that.
I was not thinking about the effects on distortion, and it all makes sense.
Now I'm thinking about cutting the bass before the phase splitter, and the treble after it.. Maybe like the old vox that had a multi position switch to switch in caps before the phase splitter to cut the lows, and then a cap and pot across the phases after the splitter, to cut the highs.
Or totally change my plans and purchase a bigger chassis, add a gain stage, and use Baxandall.. Always too many possibilities in this hobby.
I was not thinking about the effects on distortion, and it all makes sense.
Now I'm thinking about cutting the bass before the phase splitter, and the treble after it.. Maybe like the old vox that had a multi position switch to switch in caps before the phase splitter to cut the lows, and then a cap and pot across the phases after the splitter, to cut the highs.
Or totally change my plans and purchase a bigger chassis, add a gain stage, and use Baxandall.. Always too many possibilities in this hobby.
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