Well the schem posted in the zipped file says Stromrichter.org & Voltwide with the express notice not to share the drawing. A conundrum (!)
The input impedance is low indeed and not intended for direct connection to the instrument. This input should be driven by the taper of the master volume potentiometer (5~10kOhms) thus a buffer or pre-amp is required.
Besides that, I think the signal level must be around 1V, typical preamp out/power amp in values.
In some free moment I´ll try to protoboard one (no simulations for me) and drive it hard, from 500mV to 9V and see what happens.
And then will fit one between (Guitar type) preamp and power amp, driving Guitar speakers.
Mind you, I have my own (Fet based) even harmonics generator, but it´s always nice to test different solutions to the same problem 🙂
Won´t use the differential output offered because I use conventional split supply Class AB amps, not balanced ones, but suppose any of the outputs will offer all the flavour anyway.
In some free moment I´ll try to protoboard one (no simulations for me) and drive it hard, from 500mV to 9V and see what happens.
And then will fit one between (Guitar type) preamp and power amp, driving Guitar speakers.
Mind you, I have my own (Fet based) even harmonics generator, but it´s always nice to test different solutions to the same problem 🙂
Won´t use the differential output offered because I use conventional split supply Class AB amps, not balanced ones, but suppose any of the outputs will offer all the flavour anyway.
As the sum of both collector currents of the differential pair is held constant by the current source, a single output is just half of the signal and should work as well. Looking forward to your experiments.😉
Maybe that helps for testing: I append some MP3 snippets just recorded directly from my strat with TASCAM DR-40X and cut with audacity. No effects, no compressor, only normalized level.
Dropbox - strat - Simplify your life
Edit: Recording was was not electrical, but through the TASCAM stereo mic that picked up the unamplified guitar. The input source switch of my TASCAM does not connect to external line in.
Next building site...
Dropbox - strat - Simplify your life
Edit: Recording was was not electrical, but through the TASCAM stereo mic that picked up the unamplified guitar. The input source switch of my TASCAM does not connect to external line in.
Next building site...
Last edited:
next attempt, now strat recorded electrical through emu-tracker soundcard and audacity: Dropbox - stratb - Simplify your life
I've tried many devices over the years such as copper oxide junctions, non-linear resistors and radioactive suppressors but still always something missing. The jfet sziklai pair came closest imo.
Possibly the physics of the tube is way more complicated than we know and will never be able to exactly duplicate.
Possibly the physics of the tube is way more complicated than we know and will never be able to exactly duplicate.
i found a soft limiter in the 1980's which i used with electric guitar and worked very well.
simple pair of transistors in op amp feedback loop.
pot adjusts the amount of limiting.
simple pair of transistors in op amp feedback loop.
pot adjusts the amount of limiting.
yep that is interesting. I would not be able to resist changing the PNP to germanium.
So Si npn and Ge pnp.
So Si npn and Ge pnp.
Thanks, but proper signal is that from then pickups.
You can record guitar straight into any desktop computer line in, fully analog signal, you do not need an interface at all.
Some notebooks inputs can be configured for line or mic, use the first one.
Some can not, only have mic input.
You can still use it, just attenuate signal down to, say, 2 to 10 mV, microphone level.
In all cases connect guitar output to a 1M impedance buffer, simply a TL07x with a 1M resistor input to ground; op amp output through 10uF to line input or attenuated 10/22/100k to 1k divider for mic input, experiment which attenuation rate is best for your sound board.
Then proceed as usual, Audacity, whatever, to MP3 output.
You can record guitar straight into any desktop computer line in, fully analog signal, you do not need an interface at all.
Some notebooks inputs can be configured for line or mic, use the first one.
Some can not, only have mic input.
You can still use it, just attenuate signal down to, say, 2 to 10 mV, microphone level.
In all cases connect guitar output to a 1M impedance buffer, simply a TL07x with a 1M resistor input to ground; op amp output through 10uF to line input or attenuated 10/22/100k to 1k divider for mic input, experiment which attenuation rate is best for your sound board.
Then proceed as usual, Audacity, whatever, to MP3 output.
I wouldn't go that far. Some of the better software simulations are getting very good, so the guys and gals creating them obviously know a lot about how a tube guitar amp circuit actually behaves.
But I have never heard particularly good results from a fixed, frozen, "perfect" nonlinear transfer function. That always ends up sounding like a Tube Screamer, not like an actual (good) tube preamp or amplifier.
The missing ingredient seems to be that in a tube circuit, grid current flows when sufficiently overdriven, and this charges up coupling caps, causing DC bias shifts, which vary dynamically with signal level and elapsed time (since the start of each musical note). That in turn causes duty-cycle modulation of the output waveform - the duty cycle varies with the guitar signal level and frequency and duration of each picked guitar note. This means the distortion spectrum is also dynamic and changes with the guitar signal.
This makes the distortion sound change and "breathe" with guitar picking dynamics, and vary over the time duration for which a single note is held. Very different from the flat and relatively monotonous buzz you get from op-amp or BJT clippers, which do not usually exhibit any duty cycle modulation at all.
An engineer named John Murphy figured this out over 35 years ago, but it seems to have been forgotten since then: https://www.trueaudio.com/downloads/EET_jlm interview-lg.pdf
-Gnobuddy
That.
John Murphy´s dynamic distortion isalive and well in Crate amplifierts, who call it FlexWave.
And works like a charm.
Of course, since "Jimi Hendrix never used Crate" and to boost are cheap amps, it has the same stigma as Peavey does: "cheap SS amps".
Nobody cares they are KILLER sounding amps.
John Murphy´s dynamic distortion isalive and well in Crate amplifierts, who call it FlexWave.
And works like a charm.
Of course, since "Jimi Hendrix never used Crate" and to boost are cheap amps, it has the same stigma as Peavey does: "cheap SS amps".
Nobody cares they are KILLER sounding amps.
I hadn't heard of that, I'm surprised they actually made more "real" 3080s. This company makes a copy, I have no idea how it compares but I've used a couple of their synth-specific chips and they're fine. Small Bear carries this company's 3280 but not its 3080:
Operational Transconductance Amplifier (OTA)
I keep wanting to buy these newly revised specialty parts and Digikey or Mouser, but no ...
Analog Renaissance? The rebirth of the impossible chips | Electric Druid
I found a demo here: Crate Flexwave 65/112 Review II - YouTubeJMFahey said:
The guitar is out of tune (Why? Why? Why? Why is it always out of tune in 99% of You Tube demos?), and IMO the clean tone at the start of the clip is typically sterile-too-clean SS guitar amp.
But at about 2 minutes and 20 seconds into the clip, the guitarist turns up the gain, and the overdrive does sound pretty good - certainly a lot better than many other affordable solid-state guitar amps. IMO a bit too crisp and "pretty" to really sound like a tube amp, but better than the boring buzz we usually hear from the majority of SS amps and distortion pedals.
-Gnobuddy
The Peavey "TransTube" amps have similar stages in the preamp, each gain stage is two BJTs and a diode arranged to change bias on louder signals.
Tech Notes
Thank you! That was interesting reading.
I had identified some of the things Peavey's writeup discusses, and others are now widely known in the guitar-playing community. But it was very interesting to find out what Peavey's research has turned up over the years.
That said, has anybody ever heard a solid-state guitar amplifier as versatile, and as good-sounding, both clean and overdriven, and everywhere in between, as the one in this video? Playing The Incredible Amp That Nobody Knows About!! - YouTube
(For the impatient: overdriven sounds start at about 4:30, clean tones at about 7:10. And this is one of those rare You Tube demos where the guitar is actually in tune, and the guitarist actually knows what he's doing. 😀 )
-Gnobuddy
Rochester LLC seems to be just one of Digikey's many, many suppliers: Blocked
Digikey is obviously an extraordinarily efficient outfit (they seem to ship things almost before I can order them). I'm guessing they ship direct from their suppliers to their customers when that will save time and / or money.
-Gnobuddy