CABsim
The thunderchief will do as pre-amp if you want to record to pc.
If you want to keep your circuit simple and only use the runoffgroove cab sim, you will have to build an extra gain stage.
(herefor you might try the opamp design Dimitri presened earlier!!!Realy good one!)
That's my opinion after building the CAB sim an checking it out.
Barre
The thunderchief will do as pre-amp if you want to record to pc.
If you want to keep your circuit simple and only use the runoffgroove cab sim, you will have to build an extra gain stage.
(herefor you might try the opamp design Dimitri presened earlier!!!Realy good one!)
That's my opinion after building the CAB sim an checking it out.
Barre
Advice
Hello, all.
I am recording my guitar direct to PC. A have a high quality instrument( Les Paul), and cheap op-amp preamps ruin the sound.
I should probably go straight to the tube preamp, but before
that I think to try J-FET.
I know it is a stupid question, but how close J_FET comes to simulationg the tube behavior ?
I don't use lot of distortion, need instead deep bluesy sound with a lot of sustain.
Last, but not least: Even if you put J-FET or tube preamp,the sound still goes thourgh op-amps in the sound card. Wouldn't it ruin the sound ?
Sorry for unprofessional questions
Hello, all.
I am recording my guitar direct to PC. A have a high quality instrument( Les Paul), and cheap op-amp preamps ruin the sound.
I should probably go straight to the tube preamp, but before
that I think to try J-FET.
I know it is a stupid question, but how close J_FET comes to simulationg the tube behavior ?
I don't use lot of distortion, need instead deep bluesy sound with a lot of sustain.
Last, but not least: Even if you put J-FET or tube preamp,the sound still goes thourgh op-amps in the sound card. Wouldn't it ruin the sound ?
Sorry for unprofessional questions
Ahh How long have you got?
I guess the quick answer is - for 'clean' operation it can be very close.
For overdrive or distorted operation... then better than a bipolar but not really that close.
And when compared to a tube pre-amp engineered for the traditional 'toob' sound - then not a lot...
So it depends what you want from the pre-amp as to which is best.
The caveat here is that if you really understand what generates a particular sound from a pre-amp then you can use any active device to generate any sound... However this is very very rare and I for one can't do it.
ciao
James
Dont Build That One
Hey I'm certain I'm too late but there is a much much simpler JFEt pre out there that performs better.
http://www.diyguitarist.com/Guitars/FET-GuitarPreamp.htm
Go to that link. It links you to the originator of the circuit, but Paul has modified it. So far this site has been very helpful and so has the owner.
I've read a lot about this preamp online and it is said to be like sticking a 12AX7 in your guitar.
I've also spoke to a few ppl now that have built and use it regularly. They seem to swear by it.
I'm not that experienced or educated in electronics yet but I have learned that a lot of these simple circuits based on old world transistors and IC's give the richness and vibrance we're always looking to increase in our tone.
......after trying numerous dual op amps in my Crate head a 40 year old chip ended up giving me some of the best overall performance. The NE5532. I researched it's specs though and out of all the chips I was using that had specs close to a 12AX7 tube, the 5532 was by far the closest.
I ended up using it in the input buffer stage. Then gain one and gain two. I believe I have either an OPA2604 in my clean channel or an OPA2228. Both very tubey sounding. The 5532 just had great clarity and overall improvement everywhere rather than only in specific areas like the other chips gave.
I then used an OPA2228 in my reverb. No other chip that exists could outperform this chip for reverb circuits. It's imaculate.
Anyway my point is even op amps can give a tube sound in the right circuit and better yet in tube emulation circuits.
Hey I'm certain I'm too late but there is a much much simpler JFEt pre out there that performs better.
http://www.diyguitarist.com/Guitars/FET-GuitarPreamp.htm
Go to that link. It links you to the originator of the circuit, but Paul has modified it. So far this site has been very helpful and so has the owner.
I've read a lot about this preamp online and it is said to be like sticking a 12AX7 in your guitar.
I've also spoke to a few ppl now that have built and use it regularly. They seem to swear by it.
I'm not that experienced or educated in electronics yet but I have learned that a lot of these simple circuits based on old world transistors and IC's give the richness and vibrance we're always looking to increase in our tone.
......after trying numerous dual op amps in my Crate head a 40 year old chip ended up giving me some of the best overall performance. The NE5532. I researched it's specs though and out of all the chips I was using that had specs close to a 12AX7 tube, the 5532 was by far the closest.
I ended up using it in the input buffer stage. Then gain one and gain two. I believe I have either an OPA2604 in my clean channel or an OPA2228. Both very tubey sounding. The 5532 just had great clarity and overall improvement everywhere rather than only in specific areas like the other chips gave.
I then used an OPA2228 in my reverb. No other chip that exists could outperform this chip for reverb circuits. It's imaculate.
Anyway my point is even op amps can give a tube sound in the right circuit and better yet in tube emulation circuits.
http://www.till.com/articles/GuitarPreamp/
http://www.till.com/articles/PreampCable/index.html
this is tillman prepreamp, not the complete guitar JFET based preamp discussed here
from Dimitri post:
>>>>You can find one of my active guitar electronics (active wire) on my page
www.angelfire.com/az3/dimitri/
and the figures of my other front-end electronics, which was published in ETI, 1995, June are below. May be somebody can help me to find this paper as my copy had gone with the hard drive to the trash can.
Attachment: eti069501.gif
This has been downloaded 926 time(s).<<<<
I've been following this thread on and off since the day it started, and I find your preamp design very interesting Dimitri.
I am already using Don Tillman's FET Preamp Cable, and Jack Orman's Mosfet Booster in a box.
But I always wanted to combine both a FET preamp in the cable and an opamp preamp in the box. At first, I just wanted to add a simple preamp in the FET Preamp Cable box, but I find your design better. Except the +/- 15V which I could bring down to +/- 9V (2 x 9V batteries).
Do you see any problem with that option to use +/- 9V with your circuit?
I want to make a pcb layout for that purpose.
Thanks
Gilles
>>>>You can find one of my active guitar electronics (active wire) on my page
www.angelfire.com/az3/dimitri/
and the figures of my other front-end electronics, which was published in ETI, 1995, June are below. May be somebody can help me to find this paper as my copy had gone with the hard drive to the trash can.
Attachment: eti069501.gif
This has been downloaded 926 time(s).<<<<
I've been following this thread on and off since the day it started, and I find your preamp design very interesting Dimitri.
I am already using Don Tillman's FET Preamp Cable, and Jack Orman's Mosfet Booster in a box.
But I always wanted to combine both a FET preamp in the cable and an opamp preamp in the box. At first, I just wanted to add a simple preamp in the FET Preamp Cable box, but I find your design better. Except the +/- 15V which I could bring down to +/- 9V (2 x 9V batteries).
Do you see any problem with that option to use +/- 9V with your circuit?
I want to make a pcb layout for that purpose.
Thanks
Gilles
It is not a problem +-9V, you should only check current through Zener diode and omit current sink (resistor from the output of the op amp to negative rail) for battery life.
I have some reprints left from the latest Berlin AES convention named "Triode Emulator," which I can send to interested persons by ordinary mail free of charge, just wrote to ddanyuk at usa dot net. Please no request for preprint in electronic form, I don't have it. The design for a low-noise amplifier is presented. The amplifier has a tube-like transfer characteristic and produces harmonic distortion components that are similar to triode preamplifier. FET common source stage without source resistor has quadratic transfer characteristic. FET common source stage with rather large source resistor has about linear transfer characteristic. For some intermediate value of source resistor the transfer function becomes close to three halves power law, which is typical for vacuum triode.
I have some reprints left from the latest Berlin AES convention named "Triode Emulator," which I can send to interested persons by ordinary mail free of charge, just wrote to ddanyuk at usa dot net. Please no request for preprint in electronic form, I don't have it. The design for a low-noise amplifier is presented. The amplifier has a tube-like transfer characteristic and produces harmonic distortion components that are similar to triode preamplifier. FET common source stage without source resistor has quadratic transfer characteristic. FET common source stage with rather large source resistor has about linear transfer characteristic. For some intermediate value of source resistor the transfer function becomes close to three halves power law, which is typical for vacuum triode.
Ok, Thanks. I began working on a layout for the article in the ETI of 1994 this evening.
I'm interested about the article for the tube emulation... I sent you an email
Another source of info.
http://members.tripod.com/~gabevee/sstubepre.html
Gilles
I'm interested about the article for the tube emulation... I sent you an email
Another source of info.
http://members.tripod.com/~gabevee/sstubepre.html
Gilles
Hi, Peter !
You wrote that you've based your design on Albert Kreuzer bass
preamp.
>I'm putting together a JFET guitar amp at the moment. Got the >idea from Albert Kreuzer's page about the FET preamp he made >for bass.
I looked into his schematic on the net, I wonder:
What are the things that makes a difference between guitar preamp and bass preamp ?
Input impedance seems to be the same, Albert has some tone swithes that you ommited ( ultra low and bass cut), but that would not contribute a major difference in the tone of the circuit, woudl it ?
Your circuit looks identical to the Albert's, except for the swithes that I mentioned.
I admit, I did not see ANY schematic of bass preamp before, this is why I am asking about this.
Regards, George.
You wrote that you've based your design on Albert Kreuzer bass
preamp.
>I'm putting together a JFET guitar amp at the moment. Got the >idea from Albert Kreuzer's page about the FET preamp he made >for bass.
I looked into his schematic on the net, I wonder:
What are the things that makes a difference between guitar preamp and bass preamp ?
Input impedance seems to be the same, Albert has some tone swithes that you ommited ( ultra low and bass cut), but that would not contribute a major difference in the tone of the circuit, woudl it ?
Your circuit looks identical to the Albert's, except for the swithes that I mentioned.
I admit, I did not see ANY schematic of bass preamp before, this is why I am asking about this.
Regards, George.
Tube simulation stuff
quote from Dimitri:"I have some reprints left from the latest Berlin AES convention named "Triode Emulator," which I can send to interested persons by ordinary mail free of charge, just wrote to ddanyuk at usa dot net. "
Bring it on I'd say!!!Stuff like that is interesting enough for me to study
(versaevelbart@hotmail.com)
Cheers
Barre
quote from Dimitri:"I have some reprints left from the latest Berlin AES convention named "Triode Emulator," which I can send to interested persons by ordinary mail free of charge, just wrote to ddanyuk at usa dot net. "
Bring it on I'd say!!!Stuff like that is interesting enough for me to study
(versaevelbart@hotmail.com)
Cheers
Barre
Tubedistortion
I've started a new topic on simulating tubedistortion.
Maby some of you wanna check that out!
I didn't post it here, 'cause it doesn't use FET's... It's a totaly different idea.
Why did I post it?
I wanted to cher it + maby some improvements may come out of it!
Check it!
http://www.diyaudio.com/forums/showthread.php?s=&threadid=38141
Barre
I've started a new topic on simulating tubedistortion.
Maby some of you wanna check that out!
I didn't post it here, 'cause it doesn't use FET's... It's a totaly different idea.
Why did I post it?
I wanted to cher it + maby some improvements may come out of it!
Check it!
http://www.diyaudio.com/forums/showthread.php?s=&threadid=38141
Barre
Hi Peter(or whatever)
Please send me an e-mail at makoko1900@yahoo.com.ar including the Jfet guitar preamp schematic of the page www.bossaboa.dk/preamp.gif because I don´t open this page from my country.
Thank you very much and congratulation for your excellent forum.
Greeting from Argentina and sorry for my English.
Marito
Please send me an e-mail at makoko1900@yahoo.com.ar including the Jfet guitar preamp schematic of the page www.bossaboa.dk/preamp.gif because I don´t open this page from my country.
Thank you very much and congratulation for your excellent forum.
Greeting from Argentina and sorry for my English.
Marito
why not OPAMP?
Hi, I have a something offtopic question. Why not to use an OPAMP with unity gain for buffering guitar pickups? For example using TL081/2 or some instrumentation amplifier.
From http://www.muzique.com/lab/buffers.htm I see this circuit http://www.muzique.com/images/buff8.gif
Someone build it?
I know the clipping is not like tubes but if typical pickups have a peak to peak voltage between 4V and 6V, clipping occurs?
Sorry for my english.
Javier
Argentina
Hi, I have a something offtopic question. Why not to use an OPAMP with unity gain for buffering guitar pickups? For example using TL081/2 or some instrumentation amplifier.
From http://www.muzique.com/lab/buffers.htm I see this circuit http://www.muzique.com/images/buff8.gif
Someone build it?
I know the clipping is not like tubes but if typical pickups have a peak to peak voltage between 4V and 6V, clipping occurs?
Sorry for my english.
Javier
Argentina
OPAMPs do work
Hello,
Why not this and why not that.
It's just a matter of taste, if not you'll open up a can of worms and end up in a endless discussion...not getting any whiser out of it.
I've made several own opamp buffer designs, even some with bootstrapping... They all worked fine, nothing special.
My own personal experience is that the high input impedance picks up some noise and their extreme open loop gainproduct isn't neccesary to make a simple guitarbuffer.
Just a point to pay attention to.....dump you're TL072/082...they are damn old and noisy compared what the marked offers nowadays!!!
As for anything else....they work.
FET's are my personal taste though....and I still cannot give a scientificl explanation.
Hello,
Why not this and why not that.
It's just a matter of taste, if not you'll open up a can of worms and end up in a endless discussion...not getting any whiser out of it.
I've made several own opamp buffer designs, even some with bootstrapping... They all worked fine, nothing special.
My own personal experience is that the high input impedance picks up some noise and their extreme open loop gainproduct isn't neccesary to make a simple guitarbuffer.
Just a point to pay attention to.....dump you're TL072/082...they are damn old and noisy compared what the marked offers nowadays!!!
As for anything else....they work.
FET's are my personal taste though....and I still cannot give a scientificl explanation.
Op Amp Preamp for Guitar
Javier,
If you plan to use the TLO81 in the buffer circuit you describe, you may
run into some issues. First, I would recommend that you emulate the
inherent capacitance of a guitar chord by placing a 330pF capacitor from
the input cap to ground. This will optimize the tone of your pickups by
"resonating" with their inherent inductance. The input resistance is
the parallel combination of the two 1.0M Ohm resistors (500K Ohm) which
is about as low in resistance as you would want to go for this
application; any lower and you begin to "damp-out" the pickup, thus,
affecting the tone.
Secondly, for reason having to do with feedback control theory, you
would want to add an additional resistor at the output of the buffer
(between 22 and 100 Ohms should suffice). This will prevent the buffer
from oscillating when the "phase margin" is diminished by the guitar
chord capacitance.
This "instability" issue is one reason why I would NOT choose to use a
non-inverting op amp buffer in an on-board guitar preamp. I would
rather use a combination amp configuration using discrete amplifiers;
either a JFET or a high-beta transistor, as a common-source or common
emitter input stage followed by an emitter follower in the output stage.
If, however, you like the op amp solution (it is simpler), I would
choose another one that has less input noise voltage and less power
supply current drain. The TLO81 has 25nV/rootHz noise voltage and about
3.5mA current draw. There are other amplifiers available with better
noise specifications and the current draw would give you about 160 hours
of life on a healthy 9.0Volt battery (not great).
BTW: A discrete solution as previously described, can be designed with
over 3,000 hours of battery life and better noise specifications
(depending on the input transistor and circuit design). Food for
thought.
In additon: Please let me know if you want me to post a schematic of the two-stage discrete preamp. I would be happy to do so.
JP Hugsley
Javier,
If you plan to use the TLO81 in the buffer circuit you describe, you may
run into some issues. First, I would recommend that you emulate the
inherent capacitance of a guitar chord by placing a 330pF capacitor from
the input cap to ground. This will optimize the tone of your pickups by
"resonating" with their inherent inductance. The input resistance is
the parallel combination of the two 1.0M Ohm resistors (500K Ohm) which
is about as low in resistance as you would want to go for this
application; any lower and you begin to "damp-out" the pickup, thus,
affecting the tone.
Secondly, for reason having to do with feedback control theory, you
would want to add an additional resistor at the output of the buffer
(between 22 and 100 Ohms should suffice). This will prevent the buffer
from oscillating when the "phase margin" is diminished by the guitar
chord capacitance.
This "instability" issue is one reason why I would NOT choose to use a
non-inverting op amp buffer in an on-board guitar preamp. I would
rather use a combination amp configuration using discrete amplifiers;
either a JFET or a high-beta transistor, as a common-source or common
emitter input stage followed by an emitter follower in the output stage.
If, however, you like the op amp solution (it is simpler), I would
choose another one that has less input noise voltage and less power
supply current drain. The TLO81 has 25nV/rootHz noise voltage and about
3.5mA current draw. There are other amplifiers available with better
noise specifications and the current draw would give you about 160 hours
of life on a healthy 9.0Volt battery (not great).
BTW: A discrete solution as previously described, can be designed with
over 3,000 hours of battery life and better noise specifications
(depending on the input transistor and circuit design). Food for
thought.
In additon: Please let me know if you want me to post a schematic of the two-stage discrete preamp. I would be happy to do so.
JP Hugsley
Re: Op Amp Preamp for Guitar
Hi Hugsley,
Thanks for the info. Well, I'll make the buffer using JFET. Please, post the schematic if you can.
I built one using a JFET in common drain (I took it from the last stage in Albert Krauser design. After the 10th transistor it worked well. My idea is, based in Vcc, Vp and Idss, Zin, Gain, to calculate bias resistors. Right now I have 2 exams and I don't have much time, but once I have free time I'll investigate the JFET biasing.
Thanks!
Javier
Hi Hugsley,
Thanks for the info. Well, I'll make the buffer using JFET. Please, post the schematic if you can.
I built one using a JFET in common drain (I took it from the last stage in Albert Krauser design. After the 10th transistor it worked well. My idea is, based in Vcc, Vp and Idss, Zin, Gain, to calculate bias resistors. Right now I have 2 exams and I don't have much time, but once I have free time I'll investigate the JFET biasing.
Thanks!
Javier
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