Mic'ing a Mitchell-Doughnut equipped cab?

joegold

Fractal Fanatic
Hi

Does anybody out there have any experience with mic'ing a Mitchell-Doughnut equipped 1 X 12" cab (preferably open back)?

Please don't respond if you don't know what a Mitchell-Doughnut is or what it's for.
Preferably you've also got some experience mic'ing such a cab.

All comments from experienced users greatly appreciated.

Thanks
 
No comments?
Hmm.

Well I just did two gigs with Mitchell Doughnut equipped cabs (but I don't really have the most efficient type of foam yet) mic'd up and the sound guys didn't seem to even notice.
But they weren't being overly attentive anyway.

Still, it would be nice to hear from some folks with some experience at doing this themselves.

Anybody?
 
I have no experience, but some understanding of the maths
The doughnut is to stop near-parallel sound waves cancelling each other out or reinforcing each other at some distance from the driver, with a mic near the speaker you should probably work as usual, but expect that pointing a mic at the doughnut will pick up less treble than usual (unless you turned up the treble because of the doughnut!). If you are pointing the mic through the hole, I would expect little difference (again, if you turned up the treble, it will sound more trebly), if my understanding is correct, then I can understand why the sound engineer would be unaware, it would be a minor EQ tweak, same as for any different player's amp
 
You could head over to thegearpage forum and ask the doughnut man himself

Do so at your own risk. Jay will probably ridicule you for simply asking the question. He reminds me of my college organic chemistry professor who would throw something (pen, chalk, eraser, etc) at anyone who asked a question in class.
 
This would be my approach. You'll need a friend to help. Set up a mixing board and headphones or studio monitors in one room, and put your speaker cabinet in another room. Have your friend hold a mic that runs into mixing board. Then have your friend methodically move the mic in different positions in front of the cabinet while you listen in the other room while playing guitar. Tell your friend to stop moving the mic when you get a sound you like. This method works on all cabinets, doughnut or no.
 
My 1x12 is equipped with a doughnut. I found the 3/4 inch foam to take off too much top end so now I'm using 1/2 inch foam which I find to be the sweet spot - takes off some of the nasty top but doesn't cut into the presence too much.

How you would go about micing it obviously depends on a whole load of variables, the cabinet, the speaker, the kind of tone you're recording, etc. With the doughnut you can obviously get the mic quite a bit closer to the cabinet than without one, which is good if you're using a dynamic, but apart from that, my mic positioning techniques w/ a doughnutted cab aren't any different to those without.

Personally, I like to put a condenser about 4-5 feet away from the cabinet, facing the cabinet at an angle, and then for some sounds I'll also add an SM57 in the back of the cabinet and mix the two appropriately. When mic'd, the back of the cab gives you a lot of low end punch and quite a bit of presence, and can sound nice in the mix if you can sort out any phasing issues.

I really hate close micing on any kind of distorted sound, even with a doughnut it sounds so harsh and fizzy and thin its unbearable and sounds worse than going direct in, which defeats the point of going through the hassle of micing the cabinet. It's absolutely shocking to me when I watch gear demo videos and they slam an SM57 right on the grill cloth - you can't even hear the character of any equipment like that, it's just disgusting.
 
My 1x12 is equipped with a doughnut. I found the 3/4 inch foam to take off too much top end so now I'm using 1/2 inch foam which I find to be the sweet spot - takes off some of the nasty top but doesn't cut into the presence too much.

How you would go about micing it obviously depends on a whole load of variables, the cabinet, the speaker, the kind of tone you're recording, etc. With the doughnut you can obviously get the mic quite a bit closer to the cabinet than without one, which is good if you're using a dynamic, but apart from that, my mic positioning techniques w/ a doughnutted cab aren't any different to those without.

Personally, I like to put a condenser about 4-5 feet away from the cabinet, facing the cabinet at an angle, and then for some sounds I'll also add an SM57 in the back of the cabinet and mix the two appropriately. When mic'd, the back of the cab gives you a lot of low end punch and quite a bit of presence, and can sound nice in the mix if you can sort out any phasing issues.

I really hate close micing on any kind of distorted sound, even with a doughnut it sounds so harsh and fizzy and thin its unbearable and sounds worse than going direct in, which defeats the point of going through the hassle of micing the cabinet. It's absolutely shocking to me when I watch gear demo videos and they slam an SM57 right on the grill cloth - you can't even hear the character of any equipment like that, it's just disgusting.

I used to do some work for a guy that mic'd a 57 90* to the speaker, just hung it over the top of the cab. The first time I saw that I laughed and asked him why do you mic a cab like that? He replied it works fine I just shook my head and said ok. After listing to the mix I had to admit it sounded fine.
 
I used to do some work for a guy that mic'd a 57 90* to the speaker, just hung it over the top of the cab. The first time I saw that I laughed and asked him why do you mic a cab like that? He replied it works fine I just shook my head and said ok. After listing to the mix I had to admit it sounded fine.

I used to see a lot of old blues guys do that in the clubs. I thought they were just too lazy to set up a stand and do it right. I'm sure that's true.. but yeah, it actually sounds OK. Takes the ice-pick right off. Sounds kind of un-focused and 'wooly' but it works, specially for the blues :)

I used to go one better.. I left a rubbery mic clip permanently attached to a flange (like this) screwed right through the front baffle in just the right spot. With a 57 it was more like a 45 degree mic angle. I gigged that amp everywhere, just pop a 57 in the clip and the mic position was always consistent. Still lazy.. but beats hanging from the cord against the grill at 90 degrees.

flange%20mount.jpg
 
Thanks to everyone who's contributed to this tread thus far.

Assuming that some of you Mitchell Doughnut users out there are still subscribed to this thread I'd like to bounce a few more things off you guys.

How noticeable is the effect of the doughnuts with your cabs?

I've not been able to purchase the exact foam recommended by Jay from McMaster-Carr because they have some weird rules about not selling to people they don't already know in Canada.
My cabs can only take the 1/2" thick foam and I've found a couple of sources here for open-cell polyurethane foam with acoustically absorbent properties.
Both these foams do seem to have some effect with my 1 X 12" open back cabs loaded with EVM-12Ls.
But the effect is rather subtle, more subtle than I'd hoped for.
There's still a bit of ice-pick tone when you get right on-axis but it's less than w/o the doughnuts and the off-axis sound appears to be more or less unaffected.

Here's a link to the first type of foam I used that seemed to be effective:
<http://www.foambymail.com/CF/solid-charcoal-firm-foam.html>
I got them to tell me the density which they say is 1.7 lb/cu ft.

Here's a link to my most recent foam purchase:
<http://www.acoustiguard.com/conasorb-f/>
They say the density of the F-50 foam, which is what I bought, is 2 lb/cu ft.

Both products seem to do a similar job but the first one might actually sound just a bit better to me which surprised me because of its lower density.

So I'm trying to decide if I should continue to try to find a way to buy some foam with a higher density from McMaster-Carr or somewhere else.
I had a US friend on hold to buy it for me from McMaster-Carr (they won't even let me buy it with a US shipping address) but I really don't want to impose on him.
Thus far I've not been able to find any other suitable sources for foam that will sell to me here in Canada.
But if if what I've got now is more-or-less as good as it gets then I'll just move on and try to see if this will work out for me over the long run.

If anybody knows of another source besides McMaster-Carr for 1/2" open cell polyurethane foam that's acoustically absorbent and has a density of 3 lb/cu ft or more, please let me know.

Any other tips/advice/info, etc. appreciated.

[And I do plan on posting something real similar to this on TGP to see if I can get Jay himself to chime in.]
 
I place mine right at the cap edge about 1" off the cloth and have no noticeable difference from the same position as my non-donut cab.

I imagine the difference may be noticeable the further away you get from the cap.
 
The donut worked well for my 4x12. Same tone all around. I used the exact foam that was recommended. I usually mic it between the cone and the foam so that half of the mic is capturing the foamed part and half is capturing the sound coming from the cap. I sounds fine to me.
 
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