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T-Rex Replicator Analog Tape Echo Pedal Demo


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Guest Farnsbarns

I am in the process of designing my own tape echo machine. I thought long and hard about tap tempo and came to the conclusion it isn't possible without microprocessors so I canned it. I can see $600 all day with the R and D they must have put in.

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I am in the process of designing my own tape echo machine. I thought long and hard about tap tempo and came to the conclusion it isn't possible without microprocessors so I canned it. I can see $600 all day with the R and D they must have put in.

I wish it was $600. More like $900 though

 

I've never seen tap tempo done without a micro controller. The micro controllers is available in through-hole DIP packages and they're not too expensive. But yeah it would be a pain to set up.

 

What kind of tape transport are you designing? My maestro has a really badly designed system with foam pressing the tape up to the heads. I want to mod it with tension pulleys to ditch the foam

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Guest Farnsbarns

I wish it was $600. More like $900 though

 

I've never seen tap tempo done without a micro controller. The micro controllers is available in through-hole DIP packages and they're not too expensive. But yeah it would be a pain to set up.

 

What kind of tape transport are you designing? My maestro has a really badly designed system with foam pressing the tape up to the heads. I want to mod it with tension pulleys to ditch the foam

 

I saw those but then how do I translate the tapped tempo to tape speed?

 

I'm at the diagrammatic stage but tention pulleys with the heads arranged in a curve so that all the heads are covered by one sprung pulley and one freewheeling pulley. I also know I want to use 1 half of a 12au7 driving the input and the other half driving the output, allowing for a little gain/boost at the output.

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That is a very nice and impressive pedal but at that price? I'm sure it cost a lot to engineer and build but with a good digital delay, chorus and reverb pedal you can get the same effects. Just saying'...

Not really. The tape has some qualities that you don't get from a digital delay. Even a high end digital delay that specifically emulates tape echoes like the Strymon el Capistan doesn't fully capture the sound

 

It's like the difference between a tube amp and a modeling amp, though you could debate that endlessly too!

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That is a very nice and impressive pedal but at that price? I'm sure it cost a lot to engineer and build but with a good digital delay, chorus and reverb pedal you can get the same effects. Just saying'...

Just so happened to spot this one... £249

 

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I saw those but then how do I translate the tapped tempo to tape speed?

 

I'm at the diagrammatic stage but tention pulleys with the heads arranged in a curve so that all the heads are covered by one sprung pulley and one freewheeling pulley. I also know I want to use 1 half of a 12au7 driving the input and the other half driving the output, allowing for a little gain/boost at the output.

So kindof a similar transport to the WEM Copicat? That's how I've been thinking of modding my Maestro. Let me know if you have a source for the pulley hardware

 

I don't know what the tap tempo in the Trex unit is actually controlling. It could be controlling the motor speed or it could be controlling the distance between the record head and the play heads. I would think that it would be much easier to control the motor speed than create a machine to move the heads automatically/precisely.

 

So in that case you'd probably be using the microprocessor to control the voltage going to the motor, and you would need to make calculations to figure out the ratio of voltage to the motor and delay time

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...

 

I don't know what the tap tempo in the Trex unit is actually controlling. It could be controlling the motor speed or it could be controlling the distance between the record head and the play heads. I would think that it would be much easier to control the motor speed than create a machine to move the heads automatically/precisely.

 

...

As far as I got the presentation, the tap feature is accomplished by controlling the motor speed, as well as the delay times of both the playback heads in general. This will directly affect the effect's frequency response like the speed of analog tape always does.

 

The chorus function is also controlled through fast variations of tape speed.

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As far as I got the presentation, the tap feature is accomplished by controlling the motor speed, as well as the delay times of both the playback heads in general. This will directly affect the effect's frequency response like the speed of analog tape always does.

 

The chorus function is also controlled through fast variations of tape speed.

I would imagine that it is only the motor speed being affected. I didn't see anything to indicate that the play heads are movable, although obviously if you've played an Echoplex then you know that the motor speed is fixed and the playback heads are movable. I think this is a different concept that they created specifically for the tap tempo function. I could see the playback heads maybe having two positions, one closer to the record head for "slapback" settings and one position further away for longer delay time. Again I see nothing to indicate that here though, and my best guess is that the microcontroller is solely affecting the motor speed

 

And yes as you say the tape speed directly affects the fidelity. You can hear more slippage on the slower speeds in the demo.

 

I didn't know that the chorus function is actually modulating the motor speed. I would think that that would chew through tape, but maybe not

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Guest Farnsbarns

 

So in that case you'd probably be using the microprocessor to control the voltage going to the motor, and you would need to make calculations to figure out the ratio of voltage to the motor and delay time

 

And at that point I decided it was beyond the scope of practicality for DIY.

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Thanks for that Rabs. I enjoyed the Full Tone review most. My, that is a mighty machine!

 

However, there are two things I particularly like about the T rex: 1) the tap option and 2) expression pedal connection. I am sure Full Tone are more than capable of adding these options but the price is very high as it is.

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Guest Farnsbarns

So kindof a similar transport to the WEM Copicat? That's how I've been thinking of modding my Maestro. Let me know if you have a source for the pulley hardware

 

 

 

I do. I have access to lathes and machine tools. If you can get hold of Solid Edge you can design your own and send them off to a CNC shop who will load the file and can be churning them out in minutes. Shouldn't be too expensive either.

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