source for record and playback heads? or.....

[no-fi]

OK.. so I'm slowly going through all by backlog of *stuff* that I have sitting about to one day do something with.

one of these projects from years ago is a few old cuemaster 77 MK IV amp chassis (with VUs and knobs stripped... poo) but all the electronics, pots, switches, transformers, etc still in them...

I don't know how good a cuemaster mk IV is meant to be - no valves, but it's all BJTs and FETS and discrete components... plus it has transformers for mic input, line input, and line output, and it was obviously built very well - very impressive mechanical assembly.. so I figure if they went to that much trouble with the metalwork, the electronics must be alright.

Anyway - I was originally just going to get the mic preamps out of them, but looking at what I have, and going through the schematics, it looks like I have everything I need to make them into tape simulator units, except the tape heads..... (and the tape, of course...)

Now, I know nothing about tape heads, apart from the fact that they generate and respond to moving magnetic fields..... :-) does anyone here know about where I might pick up some suitable heads to play with. or have any info on what kind of transformer I might want to look at using to simulate in some way a basic record to play head connection?

Also, has anyone here ever used a cuemaster 77 MK IV? any opinions on what to expect from the electronics?


PS - I doubt I'll need more than two for my own use, so if anyone else is also interested in playing with these, I have a few spares....

[chris p]

Might I suggest that you have a chat with Rick about tape simulation first? And then proceed with the preamp project.

[no-fi]

I don't expect it will sound exactly the same as if I had a full reel to reel deck with good tape on it (so I guess calling it a "tape simulator" is a bit wrong.....) but surely it could still do something interesting to the audio?


so - anyone got any sources for suitable heads, or know what kind of impedance range and basic ratings I should look for in a transformer?

for what I want to do, i can even use heads that are way too worn to work in an actual tape deck....

[rob]

oops...could be regret # 2 post the 4 cubic metres of audio crap i threw out in the big december clean up and workshop refurbish!

Rob

[no-fi]

d'oh!

aaah well..... so.... any other suggestions besides "the adelaide tip"?
:-)

[Futureman]

d'oh!

aaah well..... so.... any other suggestions besides "the adelaide tip"?
:-)

What about some old high end cassette player? Ta@#$% etc?

You could go nuts and build a high end tape echo? lol.

[no-fi]

I was hoping not to spend much money, given it's just an experiment - also I don't want to destroy something that might already be working fine as its own thing!!
:-)

I dunno - I COULD just grab 2 of those car tape player adapters.. but it looks like they went to a lot of trouble to design the tape drive electronics.. (there's more in the record and playback amps than all the rest of the circuitry combined!) and so it'd be nice to give the electronics the kind of transducers they were designed to take advantage of.... or at least the impedance and similar coupling levels in a transformer...

I guess I could start with a $4 600:600 transformer from jaycar, and hope that's about the right impedance range. issue is I have NO IDEA what range the drive circuitry is expecting. I have the tech manual for the deck (and most of the other aussie tape decks leading upto it) but have seen no info on the actual specs of the heads... so even if I chuck in random stuff and get it "working", I have no idea how close to optimal performance that is.

[Futureman]

Hey Julian, I've got some of those transformers from that LA audio stuff.. (Same stuff I got the THAT chips from)

One was going to be your christmas present.. each unit's got 2 nice massive (well, 50mmx50mmx50mm) audio transformers in em..

[rob]

I'm a bit confused about what it is you exactly want to try and do?

a tape simulator...how? Place the play and record heads ( if you had some ) face to face?

why the enquiry about transformers? How do these factor into the simulator?

mud map needed

Rob

[Alastair Reynolds]

Hi Julian, just saw your post about Cue masters.
2UE, like all the old AM stations were full of them, difference with us is I still have a bunch of them in the 2UE Dungeon along with Manuals and schematics and spare parts,etc. You're very welcome to have one. Give me a call or email and I'll get one out and dust it off for you.

areynolds@2ue.com.au or 02-9930-9954

[no-fi]

mud map needed

yeah...

well - I have all the electronics. So idea was to just connect the record and playback amps to a pair of heads, and position the heads together so they couple. I guess this would give everything you get from recording to the tapedeck with outputs set to repro mode minus wow & flutter and minus delay time of tape moving between heads (& minus the actual tape saturation... aaah well..)

and/or - I would also like to know what kind of transformer specs I could look at getting to replace the 2 tape heads with a transformer.....

[rob]

ok. Still confused as to the "what kind of transformer specs I could look at getting to replace the 2 tape heads with a transformer....." part. Do you want to couple the record stage into the playback stage via the primary and seconday windings of a transformer? If so, then you'd need a transformer that could handle something in the order of +10dBu on the primary side and with an impedance of around 1K. The primary to secondary ratio would need to be very small, like 50:1, unless you placed a pad between the secondary and the repro circuit. ( the output level of a repro head is very small when real tape is running past it at typical tape levels ). Or you could pad down the drive level to the primary side and use a 1:1 or so transformer. But essentially there is something in the order of 60dB difference in the level going to the record head compared to what will be coming off the play head.

These figures are all very ballpark but paint the general situation you'd be dealing with

Also, either with heads facing each other or a suitable or suitably set up transformer the frequency response will be all wrong. Moving tape has a " naturally" rising frequency response, something like 3dB per octave ( from memory ), so the repro EQ circuit would have to be extensively modified.

Rob

[rick]

err believe it or not i have a box of nos cuemaster 1/4 heads somewhere !
these cuemaster were an flow on from the byer/ rola machines , but solid state

i will dig you out the heads out in the fullness of time , meanwhile i am figuring you are really stuck for a project if your making tape delays out of cuemasters !

i think you could spend much less time and effort on better ideas :)

[no-fi]

I'm not making a tape delay!
:-)

Basically I have the amp chassis sections from some cuemaster MK IVB units (minus VUs and knobs) and I was going to pull them apart to make them into mike/line preamps. they have input and output transformers and seem solidly made, so I figured they might be OK electronics.

then I got thinking, as I examined the schematics, and wondered if I could also use the tape record/playback amps, coupled together with 2 face to face heads (or a transformer?) as an additional stage in the mic/line preamps. seeing as I already have the electronics? don't expect it to sound exactly like a tape machine, but figured it could be fun?? maybe? though seeing tape itself isn't flat frequency response, if I'm not going to use tape, then I need to modify record and playback amps to have a flat response.

anyway - sounds like you have experience with the MK IV - I get the impression you don't seem to think very much of it??

[rick]

oh hell i am probably just tainted from seeing scores of them go to the tip

should be an ok mike pre though