Would this practice amp setup work?

[pappasmurfsharem]

[Logic]
Guitar In -> DPDT (that switches between two pedals, one BSIAB one cleanish (maybe a tonemender: both without tone stack) --> 3 band Tone stack --> to Switched Send jack ( meaning you have an effects loop, or can use the preamps to a guitar amp. --> SPDT to switch between a speaker sim or ruby output?

[pappasmurfsharem]

Or I guess it would be better to have the speaker sim taken out of the circuit with a dpdt and use the ruby to drive headphones?

[GibsonGM]

More info?   If you're planning on having a 3 band passive tone stack, you'll desperately NEED to have a buffer in front of it, and a recovery stage after it.  Just one transistor for each thing, or a dual opamp. Easy build.

Otherwise, you are on the right track, anyway.   See, I don't know what the specs are on some of the things you're listing in your chain.  I'd guess to say "yes, let the Ruby drive your phones" and see what happens...won't hurt to try the speaker sim, but does it eat level?   (does it have an active recovery to build up the level lost inside it - insertion loss, that's called)  If not, again you'll have to boost it.

Anyway, you LOOK to have something workable there...

[pappasmurfsharem]

More info?   If you're planning on having a 3 band passive tone stack, you'll desperately NEED to have a buffer in front of it, and a recovery stage after it.  Just one transistor for each thing, or a dual opamp. Easy build.

Otherwise, you are on the right track, anyway.   See, I don't know what the specs are on some of the things you're listing in your chain.  I'd guess to say "yes, let the Ruby drive your phones" and see what happens...won't hurt to try the speaker sim, but does it eat level?   (does it have an active recovery to build up the level lost inside it - insertion loss, that's called)  If not, again you'll have to boost it.

Anyway, you LOOK to have something workable there...

The BSIAB has enough gain on tap to take the loss of a 3 band reasonably well, but it would be a good practive to throw one in anyway.

What I am not sure about though is what to use for the "clean" channel... The Ruby has a reasonable clean sound by itself but thats why I want to share the 3 band between both "preamp" saves real estate and pots. Any idea for the clean? One thing I'm not sure of however is how to use the other side of an OPAMP for a recovery, I've seen simple buffers with opamps but not a buffer/recovery on A/B side respectively.

[pappasmurfsharem]

OK so here is what I have so far.

But I have 3 questions:

• How do I approach using the Other side of the TL072 in the "Tone Stack" section to create an appropriate recovery stage.
• I'm also not certain on what to use for the "clean" section. Would a simple booster into the tonestack work as a "clean preamp"?
• can I use the same VB from the supply section for the different points of the circuit? The tone stack buffer, and the speaker sims various VB points?

*For the ruby I removed the gain pot as I don't believe it would be necessary. I intend to just use it as a "power amp"


***RIGHT CLICK -> OPEN IN NEW TAB***

[sajy_ho]

If you want to use opamps read this page for all you need: http://www.generalguitargadgets.com/richardo/practiceamp/
Personally I don't like opamps, becouse they'll cancel all of the harmonics. I've built an amazing practice amp a month ago and that sounds awsome with my Squire:
Guitar In ----> DPDT for putting in the 'Ronoffgroove.com's Thunderchief' as the dirt channel ----> Two stages of Fetzer valve using MPF102 as clean preamp -----> Jfet buffer ----> Three knobs  Fender tone stack -----> Master volume -----> Marshall cab sim ----> Little gem mk2 (looks like Ruby but with two 386s for more headroom ----> Speaker or headphone out
The links for above circuits: (follow the instructions in Fetzer valve page and use the calculator and the second schem for the best results!)
http://www.runoffgroove.com/fetzervalve.html
http://www.runoffgroove.com/littlegem.html
http://www.runoffgroove.com/thunderchief.html

[GibsonGM]

Yes, what Saijy has going looks a lot more "vibrant", for lack of a better word...I think for the little extra effort, you'll end up with a MUCH better sounding rig!       Don't knock opamps TOO bad, ok Sajy? Ha ha. You actually can do pretty well with them if you tweak 'em...they don't actually cancel all of the harmonics - they just tend to be so high fidelity that they can sound cold if not treated right.  Don't forget, the bulk of opamps are FET input devices...

Tha said, the FET Fetzer Valve section you have going WILL lead to better sounding clipping...2nd order harmonics similar to tubes, which will be a lot warmer than your typical Si devices. And even on a clean channel, you WILL get some clipping, so they can generate a nice sound. 
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I'd try what you have drawn on the breadboard, see if it does what you want.  If not, then you find 'the cure'.   You'll want to tweak things, I'm sure, so go for it!  You won't hurt anything in experimenting...you can try feeding the tone stack right to the Ruby, or using the other opamp section to buffer/recover there, too.   If you don't use it, then use a single opamp or tie the unused section's output to its negative input, and its + input to Vb. 

Keep the Ruby gain pot, at least for now. Treat it as a "Master Volume"...you may like it!

[anchovie]

Personally I don't like opamps, becouse they'll cancel all of the harmonics.

Are you Alexander Dumble?

[pappasmurfsharem]

Yes, what Saijy has going looks a lot more "vibrant", for lack of a better word...I think for the little extra effort, you'll end up with a MUCH better sounding rig!       Don't knock opamps TOO bad, ok Sajy? Ha ha. You actually can do pretty well with them if you tweak 'em...they don't actually cancel all of the harmonics - they just tend to be so high fidelity that they can sound cold if not treated right.  Don't forget, the bulk of opamps are FET input devices...

Tha said, the FET Fetzer Valve section you have going WILL lead to better sounding clipping...2nd order harmonics similar to tubes, which will be a lot warmer than your typical Si devices. And even on a clean channel, you WILL get some clipping, so they can generate a nice sound.  
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I'd try what you have drawn on the breadboard, see if it does what you want.  If not, then you find 'the cure'.   You'll want to tweak things, I'm sure, so go for it!  You won't hurt anything in experimenting...you can try feeding the tone stack right to the Ruby, or using the other opamp section to buffer/recover there, too.   If you don't use it, then use a single opamp or tie the unused section's output to its negative input, and its + input to Vb.  

Keep the Ruby gain pot, at least for now. Treat it as a "Master Volume"...you may like it!

The Ruby already has a buffered input/volume control which should work as the master volume, No?
Why would an OP-Amp used as a buffer and/or booster kill harmonics?
Apart from the fantastic idea to use the Little Gem for more volume what would make his more "Vibrant"?

^^^
legitimate questions not being a d*ck here =)

[sajy_ho]

If you look at an opamp's schematic, you will see a lot of bipolar transistors. Here is why to avoid bipolars in a guitar amp: they have very low harmonic distortion (<.01%), and that's a very nice linear device for every electronic built including HiFi amps; But as guitar players we want the harmonics to be distorted and the sound to be coloured! and these harmonic contents are responsible of warm sound/fat sound or whatever you name it.That's why tubes are still in guitar amps, becouse of their great harmonic distortion (up to 8% !).
FETs are less linear than bipolars and can add some harmonic to the sound if being well biased, and if not, they have no differece with bipolars. You also may wonder why not to use FET input opamp, like TLO series; becouse they added those FETs for increasing input impedance, and they are the best choice as buffer stages, but as an amplifier stage (gain stage) you have no information about the value of thier Vp or IDss. For adding harmonics It's important to messure those values for each individual FET and calculate value of resistors for that device.
If you won't belive that, just build an one stage Fetzer valve accurately using  the ROG instructions and use it in front of Ruby and pay attention to the difference!

[pappasmurfsharem]

If you look at an opamp's schematic, you will see a lot of bipolar transistors. Here is why to avoid bipolars in a guitar amp: they have very low harmonic distortion (<.01%), and that's a very nice linear device for every electronic built including HiFi amps; But as guitar players we want the harmonics to be distorted and the sound to be coloured! and these harmonic contents are responsible of warm sound/fat sound or whatever you name it.That's why tubes are still in guitar amps, becouse of their great harmonic distortion (up to 8% !).
FETs are less linear than bipolars and can add some harmonic to the sound if being well biased, and if not, they have no differece with bipolars. You also may wonder why not to use FET input opamp, like TLO series; becouse they added those FETs for increasing input impedance, and they are the best choice as buffer stages, but as an amplifier stage (gain stage) you have no information about the value of thier Vp or IDss. For adding harmonics It's important to messure those values for each individual FET and calculate value of resistors for that device.
If you won't belive that, just build an one stage Fetzer valve accurately using  the ROG instructions and use it in front of Ruby and pay attention to the difference!

Right but I'm just using it as a buffer not a gain stage The distortion will be coming from the BSIABs Fets. then something else for the clean. I agree that Op amp distortion can be sterile, but when is comes to a buffer why would it matter FET vs OPAMP or are you saying that the distortion from the Fets in the BSIAB might be "sterilized" by the OPA buffer?

[sajy_ho]

If you look at an opamp's schematic, you will see a lot of bipolar transistors. Here is why to avoid bipolars in a guitar amp: they have very low harmonic distortion (<.01%), and that's a very nice linear device for every electronic built including HiFi amps; But as guitar players we want the harmonics to be distorted and the sound to be coloured! and these harmonic contents are responsible of warm sound/fat sound or whatever you name it.That's why tubes are still in guitar amps, becouse of their great harmonic distortion (up to 8% !).
FETs are less linear than bipolars and can add some harmonic to the sound if being well biased, and if not, they have no differece with bipolars. You also may wonder why not to use FET input opamp, like TLO series; becouse they added those FETs for increasing input impedance, and they are the best choice as buffer stages, but as an amplifier stage (gain stage) you have no information about the value of thier Vp or IDss. For adding harmonics It's important to messure those values for each individual FET and calculate value of resistors for that device.
If you won't belive that, just build an one stage Fetzer valve accurately using  the ROG instructions and use it in front of Ruby and pay attention to the difference!

Right but I'm just using it as a buffer not a gain stage The distortion will be coming from the BSIABs Fets. then something else for the clean. I agree that Op amp distortion can be sterile, but when is comes to a buffer why would it matter FET vs OPAMP or are you saying that the distortion from the Fets in the BSIAB might be "sterilized" by the OPA buffer?

No, you're on the right road, I'm just saying don't use opamps for the first gain stage. You can use the opamp as a nice buffer or the gain recovery stage after the tone stack, but for the first clean gain stage I suggested to use the Fetzer valve for a little tube like clean sound. That's only my taste, but you can use opamps for that too, if you like...

[ggedamed]

It doesn't matter if you use op amps in gain stages. If you don't like how they distort just don't allow them to do it.
The first gain stage is the last to distort, so when the op amp is the first gain stage and is followed by non-op amp gain stages, it add its own distortion well after all other stages distort. There are cases when an op amp first gain stage could be preferred.

But in this case, a Fetzer Valve could be indeed the best choice.

Here's some ideas:
- use a Fetzer Valve before the channel switch like sajy_ho said
- the levels at the channel switch will be different; if you don't want that, then you'd like to match them somehow
- take out the JFET and the VOL control from LM386, they were put there to buffer a guitar
- put a A100k or A200k VOL control after the tone-stack to have them interact (like in the SLO or the Dual Rectifier or countless others, see here an analysis)
- make the post-tone-stack buffer into an booster with switchable gain; with a on-off-on SPDT toggle switch you can have three gain values (including x1 for a buffer); or maybe you want to get technical and use a DIP-switch on the PCB
- connect the cabsim switch to LM386, the op amps are better at driving low impedances than JFETs and the cabsim should have around unity gain
- if you don't want the LM386 to distort you have to keep the input signal lower than 0.45Vpp; then again, some like the way LM386 distorts.

[GibsonGM]

The Ruby already has a buffered input/volume control which should work as the master volume, No?
Why would an OP-Amp used as a buffer and/or booster kill harmonics?
Apart from the fantastic idea to use the Little Gem for more volume what would make his more "Vibrant"?

^^^
legitimate questions not being a d*ck here =)

1) Ah, just didn't see the ORIGINAL for the Ruby, and assumed you would remove the VOL pot or something, and set it with fixed resistances!!!  I don't carry around schematics in my head!  (well, for a FEW things, I do, ha ha).    What you are showing is fine, yes, you will have a MV in the VOL control.

2) I never said OA's would kill harmonics - they won't.  Being silicon devices with different clipping characteristics, they will promote odd-order harmonics rather than even (Which are more pleasing).  If you don't overdrive them, they won't create ANY harmonics (extremely little...).    When using such devices, I prefer to use diodes to get distortion/clipping/OD or whatever you'd like to call it, rather than the device itself. 

FETs are of course a departure from this rule, having nice clipping characteristics.  That is why I like the Fetzer Valve, and why I say it would be a more "vibrant" setup.   Others have written why in the time since i got back to this )  Sajay is correct.....anyway, it takes like 15 minutes to slap this stuff together - I would vote for you trying it BOTH ways on breadboard, and comparing the results!!   )   Or even just build BOTH and have TWO, ha ha.

What you choose in the end depends largely on what you prefer...at times I really want a big fat SRV tone, and will go to the end of the earth to find "that kind" of saturation, clipping....other times, a POS 1 opamp driven hard into fuzz does the trick!  Don't ask me why...

[pappasmurfsharem]

If you look at an opamp's schematic, you will see a lot of bipolar transistors. Here is why to avoid bipolars in a guitar amp: they have very low harmonic distortion (<.01%), and that's a very nice linear device for every electronic built including HiFi amps; But as guitar players we want the harmonics to be distorted and the sound to be coloured! and these harmonic contents are responsible of warm sound/fat sound or whatever you name it.That's why tubes are still in guitar amps, becouse of their great harmonic distortion (up to 8% !).
FETs are less linear than bipolars and can add some harmonic to the sound if being well biased, and if not, they have no differece with bipolars. You also may wonder why not to use FET input opamp, like TLO series; becouse they added those FETs for increasing input impedance, and they are the best choice as buffer stages, but as an amplifier stage (gain stage) you have no information about the value of thier Vp or IDss. For adding harmonics It's important to messure those values for each individual FET and calculate value of resistors for that device.
If you won't belive that, just build an one stage Fetzer valve accurately using  the ROG instructions and use it in front of Ruby and pay attention to the difference!

Right but I'm just using it as a buffer not a gain stage The distortion will be coming from the BSIABs Fets. then something else for the clean. I agree that Op amp distortion can be sterile, but when is comes to a buffer why would it matter FET vs OPAMP or are you saying that the distortion from the Fets in the BSIAB might be "sterilized" by the OPA buffer?

No, you're on the right road, I'm just saying don't use opamps for the first gain stage. You can use the opamp as a nice buffer or the gain recovery stage after the tone stack, but for the first clean gain stage I suggested to use the Fetzer valve for a little tube like clean sound. That's only my taste, but you can use opamps for that too, if you like...

Ahh now I get you, I thought you were saying I should use a jfet buffer.

[pappasmurfsharem]

sajy_ho,

Any reason you chose two fetzer valves in series? vs say one?

[GibsonGM]

For a 'real tube overdrive' sound, you would use more than one stage to clip.  That's how tube amp designers do it...it's more subtle, controllable, and 'warm' than if you try to make one stage do it all.   So, I am assuming he set up two stages, each one doing some of the clipping.    As for if you wanted to put the 2nd one on a switch, you could do that to get a 'clean' and 'overdrive' setting.      On amps, sometimes you'd do a 'normal' and 'cascade' switch, kind of the same thing.

I'd also like to know how you set that up, Sajy! 

[pappasmurfsharem]

For a 'real tube overdrive' sound, you would use more than one stage to clip.  That's how tube amp designers do it...it's more subtle, controllable, and 'warm' than if you try to make one stage do it all.   So, I am assuming he set up two stages, each one doing some of the clipping.    As for if you wanted to put the 2nd one on a switch, you could do that to get a 'clean' and 'overdrive' setting.      On amps, sometimes you'd do a 'normal' and 'cascade' switch, kind of the same thing.

I'd also like to know how you set that up, Sajy!  

Well thats the BSIAB is for the gain

I figured two stages might clip which is not really what I am wanting. Granted clean amps can run through multiple stages and still be clean but those have considerably more headroom than I will in this project
then I want the other to be as clean as possible. Would one be sufficient, or are there better alternatives?

[J0K3RX]

I like what you are doing.. You might have a look at the Wampler SLOstortion schematics for some other alternative ideas

[pappasmurfsharem]

I like what you are doing.. You might have a look at the Wampler SLOstortion schematics for some other alternative ideas

That's seems to be an interesting looking tone control, from the way it's drawn it looks kind of like a James stack but with a mid control prior?. You think that might give better separation to the controls?

I'll be making boards at OSH park if your interested