Amp stands and mic placement etc.

[JeffB]

I made this short vid to see if there was any difference in sound because of cab placement.

 

http://www.youtube.com/watch?v=UReFaaIYXSU&feature=youtu.be

 

 

[H]

And what were your conclusions, Jeff?

 

I preferred the sound of the cab off the floor.

[pegleg32]

I agree with Howard. I was surprised when the third demo started that it sounded that much better. I can't imagine why it would make a bit of difference since you had the mike the same each time.

[yoslate]

Thanks, Jeff. You're always up to something interesting. I have nothing to add other than an observation. In the first two demos, the amp is in more or less (complete and lesser) contact with a carpeted floor. In the last, the amp is on a stand which appears to be made of wood. I thought it sounded best on the stand, as well.

[JeffB]

I design good amp stands. Taking orders now.

I dont know. It all sounds quite similar to me. Maybe my measurements were out a mm here and there. I thought I maintained a constant. I did think about how I would go about it.

At first I started designing and fabricating a bracket that attached to the amp and held the mic constant. But I ditched it when I considered that the cab may react differently and send different vibrations to the mic in the different positions of the cab.

Maybe 115mm is too far away from the speaker and means that some of the reflections in the room affect what the mic receives when the amp is in different positions.

When I was recording I liked the sound of the amp flat on the floor and away from my ears. I dislike guitar speakers pointed at my head.

In this vid the amp stand part of it does sound fuller and the tilted back on a DD-7 does sound less full.........I think.

Maybe the DD7 does suck tone after all.

[GuitArtMan]

I flet the biggest difference was from flat on the floor to tilted back (I preferred it tilted back) but agree it sounded best on the stand.

[koula901]

+4 on the stand - more bass response.

[JeffB]

Why is there more bass response when its on the stand?

I did design it around the same idea as a outdoor concert venue in my home town that I used to go to as a kid. "The Sound Shell". Beach side thing.

I did kind of assume there would be little to no difference between any position.

Maybe the mic should have been almost touching the grill or the grill removed and the mic set closer.

Would room reflections affect what the mic picked up even at 115mm(4.5inch's)

 

I should have gone with my original plan and also use a store bought amp stand and a plastic crate to see if there was a difference in amp stands.

 

Is the difference really that big between each sample?

[DetroitBlues]

You are using a wood stand? Would it act somewhat like a cab? Don't most production stands have rubber or foam on them absorbing some of the vibrations?

 

Think you can do another video that can demonstrate mic placement around the speaker and variance of distance?

[JeffB]

The point where the horizontal and vertical string lines intersect is the point where the mic is aimed at.

I placed a straight edge across the face of the amp and set a square on that to line up the center lines of the mic with each of the two string lines.

I checked the string lines measurements each time I moved the amp. The distance from the face of the amp to the face of the mic was 115mm.

 

I dont think that part is flawed. It seems a reasonable method....... No Im not making a video detailing that

 

The combo becomes sort of 1/3'ish closed back with that stand. Thats the flawed part. I didnt think that part through. A plastic crate or store bought stand would have been better. Not doing it again.

Stands aint stands at the end of it.

[fxdx99]

I found the comments at 0:38 and 1:14 to be most insightful.

 

I didn't really hear much difference in each demo, tho (chalk it up to old ears).

[yoslate]

 

Maybe 115mm is too far away from the speaker and means that some of the reflections in the room affect what the mic receives when the amp is in different positions.

 

 

Is that mic an SM 57, Jeff? If it is, given the 57 polar pattern, I don't think it'd be picking up much from the room even at 115mm.'s Although, putting it just at the grill cloth might give a little truer read...?

[111518]

Why is there more bass response when its on the stand?

I did design it around the same idea as a outdoor concert venue in my home town that I used to go to as a kid. "The Sound Shell". Beach side thing.

I did kind of assume there would be little to no difference between any position.

Maybe the mic should have been almost touching the grill or the grill removed and the mic set closer.

Would room reflections affect what the mic picked up even at 115mm(4.5inch's)

 

I should have gone with my original plan and also use a store bought amp stand and a plastic crate to see if there was a difference in amp stands.

 

Is the difference really that big between each sample?

Two ideas. Coupling of amp to floor increases bass when the floor resonates --if the floor is concrete, it probably dampens resonance of cab and lowers bass response. The stand might increase resonance of cab itself and thus lows.

 

Another possible factor might be the proximity of the brick wall behind the amp. The stand might increase lows by creating more space between the driver and the acoustic trap of the wall and floor. Would be interesting to try the same experiment with the amp pulled out five or six feet from the wall.

 

I absolutely could be wrong.

[slider313]

Why is there more bass response when its on the stand?

I did design it around the same idea as a outdoor concert venue in my home town that I used to go to as a kid. "The Sound Shell". Beach side thing.

I did kind of assume there would be little to no difference between any position.

Maybe the mic should have been almost touching the grill or the grill removed and the mic set closer.

Would room reflections affect what the mic picked up even at 115mm(4.5inch's)

 

I should have gone with my original plan and also use a store bought amp stand and a plastic crate to see if there was a difference in amp stands.

 

Is the difference really that big between each sample?

There's more audible bass response because of your "sound shell" design.

 

The point where the horizontal and vertical string lines intersect is the point where the mic is aimed at.

I placed a straight edge across the face of the amp and set a square on that to line up the center lines of the mic with each of the two string lines.

I checked the string lines measurements each time I moved the amp. The distance from the face of the amp to the face of the mic was 115mm.

 

I dont think that part is flawed. It seems a reasonable method....... No Im not making a video detailing that

 

The combo becomes sort of 1/3'ish closed back with that stand. Thats the flawed part. I didnt think that part through. A plastic crate or store bought stand would have been better. Not doing it again.

Stands aint stands at the end of it.

Being the combo sort of becomes a 1/3 closed back helps with loss of bass response.

[bolero]

I would agree with the wall proximity/angle to the open back combo being a factor

 

do you have a closed back cab you could try the same experiment with?

[JeffB]

I found the comments at 0:38 and 1:14 to be most insightful.

 

I didn't really hear much difference in each demo, tho (chalk it up to old ears).

I dont hear a lot of difference either. There is some but nothing that would send me adjusting tone controls or adjusting mic position if I was in a gig situation. I dont think I would even notice the difference.

I would hate to have the speaker pointing up like that. That could create some problems for me hearing other things going on and would have me driving home with ringing in my ears. Cymbals and snare are enough to contend with.

 

@Rob,

Yes it is a SM57. I thought it wouldnt pick up too much else but if I do this again I will set it 5-10mm off the grill.

 

 

I just cant remember why it seemed important to me to do this. Ive forgotten what I was trying to find. Maybe the results are so minimal it doesnt matter and its reduced the inspiration or motivation.

Seemed important while I was doing it. It was a flurry of activity.

[tulk1]

I could hear a slight difference between each position. And agreed, not enough to make me run back and change amp settings. Just as an observation, since you put this vid out: the amp stand seemed have a better overall balance, at least to my crappy headphones. Treb/Mid/Bass all seemed even. The amp on the floor certainly coupled the bass. The guys at Mesa told me once, if I really wanted my LS to boom, take it off the casters! I did, I put them back on. So, not surprised at the coupling effect. For the second vid, next time try using something besides a Boss pedal. You should have known better ...........

[111518]

This thread made me realize I didn't really understand the relationship between 1) when the amp makes other surfaces resonate, and 2) how sound waves interact when reflected in different ways by different surfaces. Found this ...

 

http://barefacedbass.com/technical-information/stage-or-floor-coupling.htm

[JeffB]

This thread made me realize I didn't really understand the relationship between 1) when the amp makes other surfaces resonate, and 2) how sound waves interact when reflected in different ways by different surfaces. Found this ...

 

http://barefacedbass.com/technical-information/stage-or-floor-coupling.htm

Thats a good read. Lots of stuff on that site is useful.

[JeffB]

I could hear a slight difference between each position. And agreed, not enough to make me run back and change amp settings. Just as an observation, since you put this vid out: the amp stand seemed have a better overall balance, at least to my crappy headphones. Treb/Mid/Bass all seemed even. The amp on the floor certainly coupled the bass. The guys at Mesa told me once, if I really wanted my LS to boom, take it off the casters! I did, I put them back on. So, not surprised at the coupling effect. For the second vid, next time try using something besides a Boss pedal. You should have known better ...........

Ive spent the last few days experimenting with different pedals. A lot of them are just repackaged clones of other things it turns out.

 

Ive also experimented with different blocks of wood at different sizes and shapes and different timbers.

I believe I have found the Grail block of wood to tilt the cab back with.

Its a precise size and shape. It enhances bottom end and sweetens the highs. the mids become more expressive. Im selling them at 59 bucks a pop

Also made some tweaks to my "Sound Shell" design amp stand. You could put a Line6 spider 15 on that sucker and have all the bloom and halo of a tube amp. Only 99 bucks.

Stop wearing your fingers out looking for the tone in them. Tone is in the amp stand. Problem solved.

[H]

Jeff knows tone.

[JeffB]

Jeff knows tone.

Yeah...I should have put some smilies in that last post

 

Ive been reading Mesa and PRS catalogs again.

[H]

Yeah...I should have put some smilies in that last post

 

Ive been reading Mesa and PRS catalogs again.

You should charge us for all this research

[tulk1]

Yeah...I should have put some smilies in that last post

 

Ive been reading Mesa and PRS catalogs again.

I got it, even without the smilies! And who would know better about repackaged pedals? ....... Hmmmmm.