Hi everybody! I think that got to the best place possible to look for help with my project.
I'm trying to build a tape delay with parts of a handheld recorder PANASONIC RQ L11.
My idea is to use just the recording heads and the motor, and would like to know what's necessary to get the signal from a guitar pickup to be recorded on the tape.
What would be the minimum circuit necessary to get the signal from the pickups to be recorded on the tape?
I want to build the circuit with as little parts as possible, because I want to mount everything inside of my guitar, so I can control the speed of the motor on the fly.
Using the actual board of the RQL11 I was able to record by soldering my input signal in place of the the mic of the recorder, but if anyone have a practical solution to put other simpler circuitry, that might just handle the signal from the guitar pickup direct to the tape, that would be perfect.
Any help will be great!
I'm trying to build a tape delay with parts of a handheld recorder PANASONIC RQ L11.
My idea is to use just the recording heads and the motor, and would like to know what's necessary to get the signal from a guitar pickup to be recorded on the tape.
What would be the minimum circuit necessary to get the signal from the pickups to be recorded on the tape?
I want to build the circuit with as little parts as possible, because I want to mount everything inside of my guitar, so I can control the speed of the motor on the fly.
Using the actual board of the RQL11 I was able to record by soldering my input signal in place of the the mic of the recorder, but if anyone have a practical solution to put other simpler circuitry, that might just handle the signal from the guitar pickup direct to the tape, that would be perfect.
Any help will be great!
Putting everything in the guitar is probably the wrong way to go about it. You need a bias oscillator to record to tape for one thing. The ultrasonic bias frequency is added to the audio to make the tape accept the audio properly so the sound will be as you expect. Also you may need some amplification/buffering, etc. The motor also needs a fair amount of power; battery power for tape delay is probably not going to be practical, not at least if that battery has to fit in the guitar.
So, better to save as much of the tape recorder as you can, and mount only a speed control inside the guitar. Either you could use wires to connect the speed control to the tape delay, or maybe you could use some type of wireless connection if you wanted to deal with the cost and complexity for that.
If you think about it, you probably have seen a real tape delay. The size of it is needed to make all the necessary parts fit inside so the thing can work. That's why you don't see them put inside guitars already.
So, better to save as much of the tape recorder as you can, and mount only a speed control inside the guitar. Either you could use wires to connect the speed control to the tape delay, or maybe you could use some type of wireless connection if you wanted to deal with the cost and complexity for that.
If you think about it, you probably have seen a real tape delay. The size of it is needed to make all the necessary parts fit inside so the thing can work. That's why you don't see them put inside guitars already.
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Didn't knew about bias, thank you, that's the missing piece of knowledge that i was looking for! Then if the recording process happens by sum of the bias with the áudio signal, by adding a bias oscillator circuit, and amplifying the pick up signal properly, i'm going to make it work, or i'm over simplifying it? 🤔
The motor, mechanics, battery part and play part are already kind of resolved... The recorder is powered by 2 AA, and i was able to reduce the handheld Recorder mechanic to just a few parts, in a way that it works as i need. To amplify the signal i'm going to use a gain booster pedal.
I have a guitar where i've digged space in the wood to fit everything, actually i use it with normal guitar pedals inside it.
Probably. A real tape delay has a few controls to tweak the sound: Record level, echo volume, echo sustain, echo on/off, echo tone. If you want to get the sound of the real deal, you have to be able to tweak the sound to fit the music. You planning to preset those things in some way, or omit features you may have liked on records you heard?
In case you don't already know, the sustain control feeds the echo output back into the input. Is that going to be included?
Anyway if you want to see what's needed according to the schematic, here is a link to the manual for an Echoplex: https://funkwerkes.com/web/wp-content/techdocs/MixedProAudio/Echoplex-Manual.pdf ...Kind of looks like V3 is the bias oscillator. Also, do you want to be able to erase the tape? If not it may always start up playing back whatever you recorded last. Maybe the end of the last song will also be the beginning of the next song?
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I found a bias oscillator circuit, but unfortunately it uses 12V, and I would like to use 9v or 3v https://www.instructables.com/Bias-Oscillator/.
Probably the solution will be using the circuit from the RQ L11 itself for the recording.
It does have what I suppose is an eraser head, but there's no wire that goes to it. When making new record to, it will override what was previously recorded. This head head fits inside a k7 with no problem
I was thinking about controlling the record volume simply by using a volume pot, same for the feedback signal and maybe a treble bleed for tone.
Probably the solution will be using the circuit from the RQ L11 itself for the recording.
It does have what I suppose is an eraser head, but there's no wire that goes to it. When making new record to, it will override what was previously recorded. This head head fits inside a k7 with no problem
I was thinking about controlling the record volume simply by using a volume pot, same for the feedback signal and maybe a treble bleed for tone.
An erase head with no wire is probably a permanent magnet. If it is in contact with the tape the magnet will erase it. Such a very low cost erase head may be mounted on a pivot so it does not contact the tape in playback mode.
For a guitar tape delay it may be the erase head is not always driven from a high enough voltage to completely erase the tape in one pass. That would a allow a sound recorded on the tape to fade out a little each time it passes by a partially energized head. Using a permanent magnet instead my produce an unsatisfactory effect.
The tape recorder electronics should include both a record head amplifier and a playback amplifier. The signal from the playback head is probably too weak to be useful without amplification. Also tape record and playback amplifiers are frequency shaped to reduce tape hiss. That equalization should probably be retained.
Strongly suggest you get this thing working on the bench first where it is easy to test, troubleshoot, and modify until it works properly. Trying to do those things with a tape recorder inside a guitar may not be very practical.
For a guitar tape delay it may be the erase head is not always driven from a high enough voltage to completely erase the tape in one pass. That would a allow a sound recorded on the tape to fade out a little each time it passes by a partially energized head. Using a permanent magnet instead my produce an unsatisfactory effect.
The tape recorder electronics should include both a record head amplifier and a playback amplifier. The signal from the playback head is probably too weak to be useful without amplification. Also tape record and playback amplifiers are frequency shaped to reduce tape hiss. That equalization should probably be retained.
Strongly suggest you get this thing working on the bench first where it is easy to test, troubleshoot, and modify until it works properly. Trying to do those things with a tape recorder inside a guitar may not be very practical.
Yes, there will be a lot of testing on the way, for sure...
Found about the hartley oscilator, that would be able to generate an adjustable bias from 50khz to 150kh, that would be a good fit. Also i'm considering the possibility of building a bias circuit with crystal oscilators, but i was able to find just 32k crystals here in brazil, the others are too high (mhz and above).
Found about the hartley oscilator, that would be able to generate an adjustable bias from 50khz to 150kh, that would be a good fit. Also i'm considering the possibility of building a bias circuit with crystal oscilators, but i was able to find just 32k crystals here in brazil, the others are too high (mhz and above).
Far as getting the guitar signal to the recorder as easily as possible.
Would be one non inverting op amp stage with whatever gain is necessary.
As mentioned as far as getting a hard slap back
you increase delay time by moving the playback head.
or slowing the tape speed.
Far as a more conventional " Delay" with regeneration or feedback.
you need a more elaborate mixer. to feedback the signal
and a adjustable level.
Again a basic mixer or adder is done with a opamp stage.
quality is issue cause your voltage is low.
with regen or feedback the extra signal quickly gets distortion.
A issue with even normal " analog" delay pedals or older bucket brigades.
was they brigade doesnt use pedal 9 volts its closer to 3 volts so distorts
horrible.
All the typical guitar pedals use a compandor chip to compress the regen
then use a expander to bring signal back to normal.
so the signal doesnt distort so bad at low levels.
AKA " analog delay" otherwise known as garbage resolution
and garbage amounts of noise.
your basically looking at typical older delay pedal circuit.
and the usual all in one compandor / expander chips
pre in pre out etc etc.
Your just replacing the bucket brigade with a tape.
and likely whatever signal level the tape head needs.
I would have to look at classic tape delays.
Bias oscillator is common for high quality tape recording.
far as I know , I doubt tape delays used bias. but could be wrong
bias is super high frequency recorded , and just aligns the tape magnetic
particles to more likely align and sound better.
if the original tape player/recorder has bias the circuit is already done.
if it doesnt have bias...then who cares lol. its delay
a erase head would have bias, many cheap recorders no erase head
so bias is not possible anyways.
Would be one non inverting op amp stage with whatever gain is necessary.
As mentioned as far as getting a hard slap back
you increase delay time by moving the playback head.
or slowing the tape speed.
Far as a more conventional " Delay" with regeneration or feedback.
you need a more elaborate mixer. to feedback the signal
and a adjustable level.
Again a basic mixer or adder is done with a opamp stage.
quality is issue cause your voltage is low.
with regen or feedback the extra signal quickly gets distortion.
A issue with even normal " analog" delay pedals or older bucket brigades.
was they brigade doesnt use pedal 9 volts its closer to 3 volts so distorts
horrible.
All the typical guitar pedals use a compandor chip to compress the regen
then use a expander to bring signal back to normal.
so the signal doesnt distort so bad at low levels.
AKA " analog delay" otherwise known as garbage resolution
and garbage amounts of noise.
your basically looking at typical older delay pedal circuit.
and the usual all in one compandor / expander chips
pre in pre out etc etc.
Your just replacing the bucket brigade with a tape.
and likely whatever signal level the tape head needs.
I would have to look at classic tape delays.
Bias oscillator is common for high quality tape recording.
far as I know , I doubt tape delays used bias. but could be wrong
bias is super high frequency recorded , and just aligns the tape magnetic
particles to more likely align and sound better.
if the original tape player/recorder has bias the circuit is already done.
if it doesnt have bias...then who cares lol. its delay
a erase head would have bias, many cheap recorders no erase head
so bias is not possible anyways.
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Compander/expander chip. This ask for a NE570 or571 ( or modern equivalent - V571, SA571,...)..
Food for thoughts:
Food for thoughts:
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Is there a single IC that could do the job of taking the signal and writing it? I’m sure back in the day there must have been. Anyone build those circuits in the 80s/90s?
The recorder your using should have everything there.
Your just getting a guitar signal to the pre already there.
As you know a guitar pickup is 8 to 12k output impedance.
So you just need a buffer with typical 1 meg input.
If the recorder needs gain you just make a gain stage.
instead of a unity gain buffer.
For the most part everybody loves to bag on " buffered" bypass
effect pedals and the true pop bypass is cooler.
Otherwise in this case if you have a " buffered" bypass pedal.
if the pedal effect is just off. it is still a active buffer only unity gain.
it would be 1 meg input impedance, no gain but atleast a impedance
match for a guitar. I dont know what gain a tape head needs.
Guitar is around 200 to 400 mV and " line level"
for most is considered the standard 1 volt.
so you need a gain of 2 or 3 at the most to be at line level
Your just getting a guitar signal to the pre already there.
As you know a guitar pickup is 8 to 12k output impedance.
So you just need a buffer with typical 1 meg input.
If the recorder needs gain you just make a gain stage.
instead of a unity gain buffer.
For the most part everybody loves to bag on " buffered" bypass
effect pedals and the true pop bypass is cooler.
Otherwise in this case if you have a " buffered" bypass pedal.
if the pedal effect is just off. it is still a active buffer only unity gain.
it would be 1 meg input impedance, no gain but atleast a impedance
match for a guitar. I dont know what gain a tape head needs.
Guitar is around 200 to 400 mV and " line level"
for most is considered the standard 1 volt.
so you need a gain of 2 or 3 at the most to be at line level
A single IC that does it is a opamp.
hundreds to chose from.
Very common is the good old low noise Fet opamps.
TL0*** series
depends if you need 1 2 or 4 opamp stages.
TL071 or TL072 or TL074
if you dont need gain and just need to match the guitar
impedance to the tape input.
The circuit is called unity gain buffer. If you need gain
Non inverting Gain stage.
Your not using dual supply your using single supply.
So there is a few need to knows.
LOL welcome to the pedal effect rabbit hole
Or as mentioned those horrible buffer bypass pedals are helpful now.
if you have a buffer bypass style pedal. just with the effect off but powered up
it is a unity gain buffer. with the correct impedance match for a guitar.
no gain, but wont be muddy. since a tape input is 10k or 100k
and your guitar wants 1 Meg.
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That’s does not do all the ultrasonic bias stuff - that’s what I was really intending.
Oh... does your tape player have a erase head.
otherwise it can be ignored.
if the tape recorder has a erase head, assume it already has bias
circuit included
I dont really think tape delay needs bias. likely left out intentionally
otherwise it can be ignored.
if the tape recorder has a erase head, assume it already has bias
circuit included
I dont really think tape delay needs bias. likely left out intentionally
Im sure there is
I dont know off hand.
I did a quick search and sanyo did a lot of all in one chips for tape recorders.
All seemed to be pre in pre out, didnt catch anything for bias.
I played around with tape loopers and delays
but just used the included circuits from the machine.
many had no erase head, so bias not needed.
I dont know off hand.
I did a quick search and sanyo did a lot of all in one chips for tape recorders.
All seemed to be pre in pre out, didnt catch anything for bias.
I played around with tape loopers and delays
but just used the included circuits from the machine.
many had no erase head, so bias not needed.
If you look at the linked manual for an EchoPlex in #5, V3 appears to be the bias oscillator.
Ahh ok, cool cool.
That would have been a good one to look at.
they did use a erase head
Either way the existing unit your trying to modify should
already have all the circuits for bias.
You just interested in getting guitar signal to a tape recorder.
As far as the ideas with speed control and cables going to your guitar.
Those are thing we all thought off.
Butt realized a good delay you can manipulate live or when playing.
You just want treadle pedal / foot control.
Minimum of course delay time.
The best as you know being a delay master LOL
would be a pedal for delay time.
and pedal for feedback/ regen
just do that with anything with expression pedal.
like boss. Or find endless used rack effects cheap
with expression pedals. basically roland/boss
makes the treadle pedals and effect since 80's.
50 years of used stuff everywhere. specially old racks
nobody uses.
That would have been a good one to look at.
they did use a erase head
Either way the existing unit your trying to modify should
already have all the circuits for bias.
You just interested in getting guitar signal to a tape recorder.
As far as the ideas with speed control and cables going to your guitar.
Those are thing we all thought off.
Butt realized a good delay you can manipulate live or when playing.
You just want treadle pedal / foot control.
Minimum of course delay time.
The best as you know being a delay master LOL
would be a pedal for delay time.
and pedal for feedback/ regen
just do that with anything with expression pedal.
like boss. Or find endless used rack effects cheap
with expression pedals. basically roland/boss
makes the treadle pedals and effect since 80's.
50 years of used stuff everywhere. specially old racks
nobody uses.
One likely problem is the motor makes a lot of "magnetic" noise that will surely be picked up by the pickup. Stopping that from happening is the biggest challenge with the mechanism mounted in the guitar, and is a good a reason as any to have this thing be a pedal or something that's well away from the guitar pickups.