Tape Head Saturation - Just a quick sanity check...

[jBam]

Hi all,

Dreaming up another stupid idea; just interested in opinions /discussion here, and it's probably something that's simply not worth doing.

Tape Head to Tape Head (no actual tape) for generating saturation...  I've been dreaming this one up for years.  I (of course) searched here now prior to posting, and this is discussed here:

https://groupdiy.com/index.php?topic=39135.msg483020#msg483020

Particular focus on the following makes me realise it's a crap idea (most likely):

"Also know that you're not going to get soft saturation from the tape heads alone, more like hard clipping and ring modulation-like nasty artifacts. Tape saturation comes entirely from the media itself and the tape heads alone have more headroom above the actual media saturation point. But the head clip might still make a cool distortion effect." (from a member here "Kingston"- thanks !)

There's a few other good posts.

So I give up... start dreaming up more stupid ideas, and then get drawn back in by this site / article that claims good things come from the tape heads alone...

http://blog.dubspot.com/cassette-tape-saturation-technique/

Kinda obnoxious example in the 1st vid; but now not sure if I'm back on board with the idea.  2nd vid sounds horrid haha...

I guess my questions are:


- Has anyone messed around in this space further?
- Is nice saturation all in the tape media itself (as suggested in the quote above)?
- If so, could that perhaps be faked by placing tape (perhaps layered over and over a few times) between two heads?
- Seems clear from the vids that you can pump up some heavy distortion, but I wonder if that may even be the head amps distorting due to the overload?  Any further thoughts on head-to-head heavy distortion as a usable effect (i.e. distortion due to the head / magnetic limits, rather than other circuitry)?

 

[bluebird]

I tried messing around with the concept a long time ago. I think I used an old 1/4" reel to reel and basically just put the record head on the play head with some kind of plastic between them. Forgot the details. I kind of remember it sounding ok but not really cool enough to justify a big reel to reel sitting on my desk.

 

[Monte McGuire]

If you connect two tape heads together, isn't this the same as a transformer?

 

[jBam]

I tried messing around with the concept a long time ago. I think I used an old 1/4" reel to reel and basically just put the record head on the play head with some kind of plastic between them. Forgot the details. I kind of remember it sounding ok but not really cool enough to justify a big reel to reel sitting on my desk.

ok cool - thanks mate. I might touch base with you if I look further into it...!

 

[Tubetec]

I believe there are a number of quality units out there ,including at least one by his royal highniness Rupert that use a similar idea to what you have ,Empirical labs fatso is  another machine based around the same principle,my belief is that almost any iron in the signal path, nicely driven,  can have a similar effect sonically ,I did a blues tape with a buddy a few years ago ,a three head double speed cassette machine allowed me to dial in the required saturation ,really added alot of growl especially on the vocal peaks, your probably running into several % points THD ,but the result isnt like say an op-amp being driven ,which just turns to a brittle high harmonic mush .It was common back in the tube days to specify amps to 5% harmonic at full output ,your average op-amp will rip your ears appart when driven in this manner ,class A topologies sound sweeter when over driven than A\B and B which is what your getting from op amps  .You could try putting together a nice class A transformer coupled tube preamp ,pad down the output ,and drive the tits out of it ,its more like a compressor with a little added fizz or brightness on the peaks,attack and recovery are more or less instantainious .The Stooges have always been my reference point for heavy tape saturation in recording,really adds a bite to vocals in particular .Anyhow hope thats some help .

 

[jBam]

If you connect two tape heads together, isn't this the same as a transformer?

Yeah - kinda wondered the same thing myself. Windings and magnets... I might look back into the basic principles of a tape head... The more I think about it the more I feel like nice tape saturation most likely lies in... Yup: the tape haha...

Kinda points toward the notion of the second link in my original post being full of s#*t...

 

[jBam]

I believe there are a number of quality units out there ,including at least one by his royal highniness Rupert that use a similar idea to what you have ,Empirical labs fatso is  another machine based around the same principle,my belief is that almost any iron in the signal path, nicely driven,  can have a similar effect sonically...

Curious... OK cool...  Time for some more thinking then!  There may be something here worth dreaming up (although it appears to have already been dreamt of!)...

I was slightly under the impression that Fatso used PWM trickery in that space --> mind you; that's a completely unfounded opinion and one that someone here can probably clarify quickly~!?

Thanks for your insight though...  the mind continues to wander

 

[jBam]

Yes - ok... here's the neve stuff (I assume):

http://rupertneve.com/products/542/

So this does adopt an approach along the lines of physical tape head simulation - tidies up thoughts on transformer vs tape head too; noting that it uses a transformer as a fake record head...  Interesting...

 

[Tubetec]

Op amps in the same way a digital systems tend to turn to dirt when over driven ,old fashioned class A analogue tends to have a more forgiving  overload characteristic ,the more simplistic your circuit the more gracefull the overload,to this end circiuts involving large amounts of NFB tend to get ugly real quick when overdriven .The closer to pure second harmonic your circuit produces the better ,IMHO. its a bit like a built in limiter ,depending on how you set the gain

 

[abbey road d enfer]

If you connect two tape heads together, isn't this the same as a transformer?

Yes. But if a transformer was made with a low saturation/high coercivity magnetic material, such as the oxide coating of a magnetic tape, and a loose coupling coefficient, it is very likely to emulate rather well a tape recorder. After all, a tape recorder is a transformer in which the magnetic flux is displaced in time.

 

[pvision]

After all, a tape recorder is a transformer in which the magnetic flux is displaced in time.

It also has pre-emphasis & de-emphasis which will tend to change the nature of the distortion generated

Nick Froome

 

[Kingston]

Yes. But if a transformer was made with a low saturation/high coercivity magnetic material, such as the oxide coating of a magnetic tape, and a loose coupling coefficient, it is very likely to emulate rather well a tape recorder. After all, a tape recorder is a transformer in which the magnetic flux is displaced in time.

Wow, a quote for the ages. I wouldn't downplay the fact the media itself has very limited capability of carrying the flux. It's the primary source of distortion.

 

[abbey road d enfer]

Wow, a quote for the ages. I wouldn't downplay the fact the media itself has very limited capability of carrying the flux. It's the primary source of distortion.

That's what I meant by low saturation.

 

[Gene Pink]

Yes. But if a transformer was made with a low saturation/high coercivity magnetic material, such as the oxide coating of a magnetic tape,...

Hmmm...

 

[jBam]

Hmmm...

*thumbs-up* 

 

[jBam]

So the mind keeps wandering into how things reallllly work in the tape world.  Physically that is.  I realise I really don't understand a lot about it, which doesn't surprise me since I haven't really thought about it before!  There's also surprisingly very little on the net that I can find that really explains exactly what's going on at the tape side of things - good resources, yes; but not really a detailed explanation of how amplitude / storage is taking place a physics level on the tape that would aid in me realising "ahh - ok ---> I understand"...

That said, I've read a heap over the past day, and have formed an opinion on  tape and saturation that I've love someone to qualify or completely destroy~!

1) Tape reads / writes longitudinally along the tape. 

2) How does amplitude work then - ?  I'm assuming like this: the magnetic orientation of emulsion on blank tape is random (or more likely fixed side-to-side by an erase head?? something like that).  Low levels in recording cause a relatively small amount of the emulsion to reorient longitudinally (back and forth, presenting a + / - storage of amplitude), but not all reorient.  Large amplitudes cause more of the emulsion to reorient.  Peak amplitudes effectively makes all of the emulsion to reorient.  Is THAT correct to amplitude?  I'm having trouble understanding tape basics here, but that's what I've come up with!!

3) If I'm correct in 2 above, then high freq saturation starts to make sense - at loud volumes (amplitude), smaller variations in reorientation from high frequencies are competing with an overwhelming orientation from larger more dominant lower frequency reorientation.  It will still be present, but it is less able to reorient a significant portion of the emulsion - in fact, it's pretty much impractical to consider significant reorientation in this scenario, as that would introduce insane harmonics.

---

All that said, I've probably got the whole thing / concept wrong haha...  please debunk!!

At the end of the day, if I (others) can understand the process in detail, it might be reproduced in a static sense (i.e. without moving tape) - I mean ---> yes, others have done it anyway (EDIT: well not necessarily in full; but static tape simulation hardware exists); but just interested in the whole concept.  If not in a practical sense, then just theoretically...  It would be quite the thing if the tape medium itself could be physically replicated in a static gadget...

 

[bluebird]

Hey Gene, thats a cool idea! Id imagine the core would have to be pretty big to get it to pass 20hz with all the plastic in there. Try it with a reel of 2" tape...Lol.

Or try putting a couple tape heads on either side of one of these...

 

[bluebird]

Seriously though, I think plugins have come pretty far with the tape saturation thing. Seems like everyone is using the UAD tape machine plugin these days. I get a lot mixes that have been way over done with tape saturation.  Massey also makes a decent tape simulation plugin. Its cool to go down the road for educational purposes but even if you spend a bunch of time, money and effort building something, I can guarantee its not going to sound any better or be more convenient to use than all the offerings analog and digital that are already out there.

While on the road of tape saturation discovery, try messing with diode and transistor soft clipping. You can entertain yourself for months with a hand full of diodes...

 

[jBam]

Seriously though, I think plugins have come pretty far with the tape saturation thing. Seems like everyone is using the UAD tape machine plugin these days. I get a lot mixes that have been way over done with tape saturation.  Massey also makes a decent tape simulation plugin. Its cool to go down the road for educational purposes but even if you spend a bunch of time, money and effort building something, I can guarantee its not going to sound any better or be more convenient to use than all the offerings analog and digital that are already out there.

While on the road of tape saturation discovery, try messing with diode and transistor soft clipping. You can entertain yourself for months with a hand full of diodes...

Hey Bluebird - yes absolutely...  Mostly educational / abstract interest here...! 

I've developed up some interesting soft clipping schems / concepts in the past too ---> actually more VCA based, since there's a well founded world of other methods such as diodes as you suggest (while vca soft clipping is relatively un-touched from what I've seen).  Quite interesting with non-linear vca topo, as high frequencies get absorbed (or more-so soft clipped) more at higher levels; and very controllable in terms of depth (start point) and degree of soft clipping (particularly if you run a second soft-clipper OR hmmm... soft expander or whatever it is I've done, on the sidechain signal.  But meh - it's all just simulated at this stage anyway ... like I said - educational abstract thoughts and theories

It's that VCA soft clipper that led me to thinking more about tape saturation; and then the general topic here... etc.

Thanks for the diode party in your attachment too!  I actually haven't explored the options in this space much...

 

[bluebird]

But meh - it's all just simulated at this stage anyway ...

Well get some parts on a bread board young man!
I have a couple bread boards outfitted with a INA134 line reciver and an XLR pig tail at one end, and a DRV134 Line driver with XLR pigtail at the other end.  I can do anything in between them I want, whenever. Just hook it up too pro tools for messing around with different circuits. That setup would be perfect for a passive diode circuit. Throw an op amp in after the line receiver for gain into the diode network.