Watkins Copicat Mods anyone?

[Paul Fury 161]

Hi all. I have an old Watkins copicat mk2 (5 heads, fixed tape speed),just wondering if it's possible to mod it for sound on sound(erase head disconnected), and to disconnect the input from the mixer stage to allow it to be used for mixing on an aux with no dry signal? Guessing i should just be able to drill the top, put two switches in to break the circuits at the approaproate points - anybody ever done this?Is there anything I should know on advance?

Sorry for yet more stupid q's, hope everybody's doing ok,
Cheers,
Thanks in advance,
Paul

p.s. everybody who clones any of the vintage british pre's, eq's and comps should lcheck to "Bowie at the Beeb" 2-CD set, if you're in the UK, I bought a copy from music Zone for £9.97, awesome late 60's radio session sound, those BBC
guys frickin ROCK!

 

[Bo Hansen]

Paul,

I don`t know if this Copicat are a mk1 or mk2,
http://web.telia.com/~u31641623/WEM%20Copicat%20tube%20echo.jpg
but if it is same that you have, it have a magnet as erase head, placed in the tape roller and tension arm, so it can be difficult to disconnect.

The direct/dry signal is more easy to fix, disconnect the two 1 mohm resistor from the wiper on the two 500 kohm input gain controls.

BTW, this machine have a very poor drive capasity to feed a line or a echo return input on a mixing console, it is a good idea to build in a tube cathode follower or a FET transistor buffer after the 500 kohm echo volume potentiometer (without 470 kohm resistor from the wiper)

--Bo

 

[Paul Fury 161]

Hi Bo, thanks for the reply. Mine is a solid state model, mark 2/3, I'm pretty sure that the erase head is a discrete head (mine has five;erase,record,and 3xplayback). They actually made some that look almost identical to mine that had the sound on sound feature, so i'm fairly confident i should be possible. Thanks for the good hints for disconeccting the dry sound, sounds like it shouldn't be too difficult even for a newbie like me.I'm basically looking to fit two switches on the top panel to make both things switchable, to allow me to use it on an aux with my mixer, or still as a straight through guitar effect like normal.

The FET follower is a good idea, I just wonder if it wouldn't make the output too hot for a conventional guitar amp? I'm definitely gonna have a think about that anyways.

Thanks all,

any more comments would be appreciated,

this board is great, and you guys and girls all rock it big style!

cheers,

Paul Fury 161

 

[Bo Hansen]

Paul,

Ok, it was a guess with the old tube Copicat, (I think there was a mk2 tube echo)

Any way, I try again,
Maybe your mk-2 are similar to this solid state mk-IV, that have a real erase head. (and total five heads)
http://web.telia.com/~u31641623/WEM%20Copicat%20mk-IV%20echo.jpg

Here is easy to disconnect both erase and record head.
The erase head is the head with a X on the schematic, and you can insert a switch on the upper head connection.
The record head is the head on left side of the erase head, and here you can also insert a switch in same way.

The direct/dry signal can be switch on/off if you insert a switch between the 2,5 uF capacitor and the 82k resistor, placed on the third (from left) BC108 transistor emitter leg.

The output on this Copicat have better drive capasity, but even here is a good idea to add a emitter follower on the output.

BTW,
A cathode follower, FET-buffer/source follower or a emitter follower have no gain, so it will not change anything when you use it to a guitar amp, but it will help when you use long cables and mixing console line inputs.

--Bo

 

[Paul Fury 161]

Hiya,
Thanks Bo, that's great stuff, exactly what I needed. Thank you for your patience and knowledge - the people on here make this board a great thing.

Take it easy all,

Cheers,

Paul Fury 161

 

[kevin thoms]

Is there anyway to make one of these units varispeed ie... slow or speed up the motor?

 

[abbey road d enfer]

Hi all. I have an old Watkins copicat mk2 (5 heads, fixed tape speed),just wondering if it's possible to mod it for sound on sound(erase head disconnected),

If you just disconnect the head, the oscillator will drift significantly, considerably changing the record performance. You should replace the head with a "dummy head", an inductance of similar value.

 

[tardishead]

I have a copicat MK4 - I did this erase head bypass modification - seems to work well. However the switch always "pops" and consequently the pop gets recorded onto the tape. How do I make the switch popless??

I presume this mod can be done on any tape machine with an erase head. All that is necessary is to find an inductor of similar value to the erase head?

Should the record head be bypassed in a similar manner??

 

[thomasdf]

I am interested in schematics of a fet driver for the output, if someone has it?
I have a '66 Custom Copicat (tube all the way except for the output stage where there is a AC136 (if my memory serves me well) transistor). Do I need an additional emitter / follower?

 

[Whoops]

I know this is an old thread but I'm performing this mods at the moment.

For a Wet signal only output no major mods are needed, just take that signal from the footswitch.
The signal that goes to the footswitch is just the wet signal, you can cut the footswitch cable and insert there a female jack plug, and then a male jack on the cable that goes to the footswitch.
This way you can use the female jack as a wet signal output, but you can also still use the footswitch if you want.

For the Sound on Sound feature, I have one machine that has that feature and I will see how it was performed on that unit and will publish it here once I open it.

For the Varispeed I think it's more difficult, probably it's a matter of dropping the voltage going to the motor, dont know how easy or feasible that would be.
Will check that also.

Some other good mods are also:
- adding a Earth plug to the copicat with proper ground connection to the case.
- Changing the Filter caps for New ones, can also increase the value of the Filter caps since new caps are much smaller.
- And also routing the Output cable signal and Footswitch out cable though a different place than the Power cable.

 

[thomasdf]

Hi all
I had mine checked a serviced by a tube technician. With a guitar and an amp it behaves delightfully, but inserted on converters or modern studio gear, there is a impedance / load problem I believe, and all the low end is gone, and it sounds gritty and distorted.
I tried DI / reamps and wasn't great either, so my last try will be a couple of isolation transformers to match the impedance of my converters -modern line level- (somewhere between 600 ohms and 10K, probably more 10K) and the copicat.
Do anybody know the ideal impedance the copicat would like to see at its input and output?
Thanks a lot
Thomas

 

[Tubetec]

I would say at least 1 M Ohm on the output of the copicat would be minimum ,signal stepdown  transformer wont really have a high enough impedence to do the job ,an active Di box preferably with an input impedence of several megaohms would be better .

 

[CJ]

just stuck a tape on one of these, blows the echoplex away IMHO,

got 10 loops for 20 bucks with fast and cheap shipping from here>

http://www.mytapeecho.com/

 

[Whoops]

Hi all
I had mine checked a serviced by a tube technician. With a guitar and an amp it behaves delightfully, but inserted on converters or modern studio gear, there is a impedance / load problem I believe, and all the low end is gone, and it sounds gritty and distorted.
I tried DI / reamps and wasn't great either, so my last try will be a couple of isolation transformers to match the impedance of my converters -modern line level- (somewhere between 600 ohms and 10K, probably more 10K) and the copicat.
Do anybody know the ideal impedance the copicat would like to see at its input and output?
Thanks a lot
Thomas

what unit do you have?

I have an MK IV solid state unit and never had the problem you are describing.
I use it with Protools and apogee converters, Reamp on the input and DI on the output, works great and sound really good.
Could it be because it's a tube unit and the impedance is different than solid state units?

 

[thomasdf]

Hello
It is a Custom Copicat (tube copicat from 1966 with a germanium transistor output buffer)
Dry signal is ok, but the echo is really distorted...
I had it recapped and checked but 200€ later it didnt change much after all 

 

[Whoops]

Hello
It is a Custom Copicat (tube copicat from 1966 with a germanium transistor output buffer)
Dry signal is ok, but the echo is really distorted...
I had it recapped and checked but 200€ later it didnt change much after all 

Could be worn heads.