Author Topic: Heads - What to look for?  (Read 1933 times)

Offline ozmillsy

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Heads - What to look for?
« on: November 15, 2012, 08:41:37 PM »
Hey Guys,  I've just received a pic of the heads of the PR99 I bought.  

Q for those who are knowledgable with R2R decks,   what do we look for in this pic?  

There are what looks like some wear tracks, where it looks like the tape runs (yellow arrow) , seems to look normal/round/good.

Or where I've put the pink arrows,  is this a flat spot? 



Any advise would be really appreciated.

It would be great if this thread can start to capture pictures of heads that have problems (flat spots, cracks, anything else we should look for?).    No cheeky head comments please.   :P
« Last Edit: November 16, 2012, 12:08:47 AM by ozmillsy »
It's all about the music,, not the equipment.

Offline ozmillsy

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Re: Heads - What to look for?
« Reply #1 on: November 16, 2012, 12:09:39 AM »
Oh, and they both look shiny like mirrors.   I assume this is a good thing??   8)
It's all about the music,, not the equipment.

Offline vitavoxdude

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Re: Heads - What to look for?
« Reply #2 on: November 16, 2012, 01:20:22 AM »
Yes they look fine.  What happens is the curved profile becomes flat at the apex and it is the width of the flat that determines if the heads can be 'relaped' or not.  If not then figure on a couple of hundred dollars to have the replay head replaced and realigned.   Relapping is a physical fine re grind to return the head to the curved profile the best I can make out.  The flat extends across the face of the heads not the tiny nich at the base of your images ( this may well be a wear guide to replacement)  Its pretty hard with the reflective image of the magnetic shield being shown on the head face to easily see the exact status.  :D I purchased a brand new head block at considerable expence and had the old heads relapped as spares, the machine was then realigned with test tones from a setup and alignment tape and then the bias was set for the tape formulation I could still buy!

Oh what fun, hope your bearings and brake bands are good.  The electronics in the PR99 are a bit sad with el cheapo opamps but the signal can be taken directly from the tape heads to an external valve head amp - so much better than the fairly nasty silicone.  That's the next stage for me after Graham get's the TP tapes sorted.  I note there is a chap over East who is offering a great service for replacing all those 30 plus year old capacitors etc in the Revox range, price looks very reasonable too, to be commended and recommended.

There is plenty of information available on the web, just type in Studer or revox into Google and way you go.  ;D
V
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline vitavoxdude

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Re: Heads - What to look for?
« Reply #3 on: November 16, 2012, 01:27:28 AM »
Oh, and they both look shiny like mirrors.   I assume this is a good thing??   8)
Yes they are nice and clean and smooth which is exactly what you need for constant tape contact and no tape drop outs.  Try some Nufinish car polish (ebay ref Item number: 120758028195) on old tapes to remove oxide before it sheds all over the heads, it's a good thing to clean them each play before spooling, the polish can be used on the heads too and then buffed off, its what people on the forums reckon is effective. Your wifes makup removal pads make good pads to wipe the tape past and you can see the oxide / gunk dirtying the surface. Try to find a demagntiser too to periodically demag the heads, this will keep the machine in tip top record and replay shape.

Hope this helps
V
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline stevenvalve

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Re: Heads - What to look for?
« Reply #4 on: November 16, 2012, 01:35:22 AM »
but the signal can be taken directly from the tape heads to an external valve head amp - so much better than the fairly nasty silicone.  That's the next stage for me
Yes that's is my next move as well, Lets check out the external valve head amps around. I may get paul to make one with the right bits.

Offline stevenvalve

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Re: Heads - What to look for?
« Reply #5 on: November 16, 2012, 01:39:23 AM »
Oh, and they both look shiny like mirrors.   I assume this is a good thing??   8)
Yes they are nice and clean and smooth which is exactly what you need for constant tape contact and no tape drop outs.  Try some Nufinish car polish (ebay ref Item number: 120758028195) on old tapes to remove oxide before it sheds all over the heads, it's a good thing to clean them each play before spooling, the polish can be used on the heads too and then buffed off, its what people on the forums reckon is effective. Your wifes makup removal pads make good pads to wipe the tape past and you can see the oxide / gunk dirtying the surface. Try to find a demagntiser too to periodically demag the heads, this will keep the machine in tip top record and replay shape.

Hope this helps
V
V. I am glad you know your stuff, because i am new to this tape game, but i will learn fast.

Offline vitavoxdude

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Re: Heads - What to look for?
« Reply #6 on: November 16, 2012, 01:41:09 AM »
Yeah Steve, doctour bottlehead makes two units suitable and there is a DIY kit which is priced much more attractively.  ;D
V
We all like different things so lets all agree to disagree and if any common ground is found then worship it.  Mine is the KD hence being present on this forum.

Offline ozmillsy

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Re: Heads - What to look for?
« Reply #7 on: November 16, 2012, 02:56:18 AM »
Hey V, thanks for the feedback. 

Oh what fun, hope your bearings and brake bands are good. 

Hope so.  This unit was checked and any issues fixed around 8 months ago (current owner bought it from the tech, Zoran, mentioned in the other thread).  Seller says he has hardly used it since, and is selling off all his studio gear.   Fingers crossed it's technically "sound".
 
Quote
I note there is a chap over East who is offering a great service for replacing all those 30 plus year old capacitors etc in the Revox range, price looks very reasonable too, to be commended and recommended.

Which guy is that?  I'd like to look into that.

Cant wait to get it here.

I do have some old R2R major studio release tapes that are quite old, and thanks for the tip on cleaning them.   But I am not sure if they're suitable?   They're 7.5", and I am not sure about the EQ profile they were mastered with.  Is there any way to find out?   Is it relevant?    I'm not expecting high quality with these old tapes, but some of them I'd like to give a try after cleaning if possible (eg: High Society soundtrack is 1 of my old tapes)
It's all about the music,, not the equipment.

Offline zenelectro

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Re: Heads - What to look for?
« Reply #8 on: November 16, 2012, 09:41:56 AM »
but the signal can be taken directly from the tape heads to an external valve head amp - so much better than the fairly nasty silicone.  That's the next stage for me
Yes that's is my next move as well, Lets check out the external valve head amps around. I may get paul to make one with the right bits.

Making a good valve replay electronics is not trivial.

You need a whole lot of stuff like various EQ curves, bias traps and super low noise. You also need
adjustment of those EQ's which are set from calibration tapes. I have a friend who used to set up
a lot of the pro studio 2 inch machines in Sydney, optimal set up of the replay is a bit of an art.

WRT your player, the Tascam electronics are actually better than most give credit to. If the player you have is
similar to a (semi)pro 16 track 1 inch machine I had years ago, the electronics were all discrete, high slew very
low noise.

FWIW, I've seen Studer pro tape machine electronics with numerous opamps in the path.

If you want simple upgrade, a dedicated replay electronics power supply is not a bad place to start.

If you are really serious, cut to the chase and buy an Ampex ATR 102. Best non-custom 1/4" 1/2" R2R ever made.
There are quite a few around because every one knew this. You should be able to pick one up for around 3 grand.


Z
 

Offline micoz

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Re: Heads - What to look for?
« Reply #9 on: November 19, 2012, 05:41:36 PM »
Interesting page with pictures. 

http://www.analogrules.com/badheads.html

Offline gamve

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Re: Heads - What to look for?
« Reply #10 on: November 19, 2012, 07:18:43 PM »
Interesting page with pictures. 

http://www.analogrules.com/badheads.html

Good post.I was looking for this page to show some of the others :)