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iso cab ''ACOUSTIC'' Dynamic Microphones
Old 14th September 2011
  #1
Gear Maniac
 
Vince Latulippe's Avatar
 

iso cab ''ACOUSTIC''

Alright, i just built myself an iso cab made out of MDF 5/8''. i put two layer of 1'' SONOpan (go check out on youtube). one layer of sonopan is like 3'' of Roxul Sanf N' Sound. My problem is not with the inside of the the box (recording part) but with the ''outside'' when i play with the clean channel of my Rectifier Rectoverb, there is absolutely no problem. but when i play with the distortion, it gets really bassy.

here's my iso cab ImageShack Album - 17 images

the ''false bottom'' is for a air circulation so i have a positive pressure. i drilled two 1/4 holes on the bottoms of the iso cab.

what should i do to reduce the bass that i ear from outside the box.

the bass is so loud that i have to put the master at like 1.5.

oh and i almost forgot, in front of the speaker, i put two layer of SONOpan on the bottom where the mic will be places.

thanks

Vince
Old 15th September 2011
  #2
Gear Maniac
 
Vince Latulippe's Avatar
 

anyone ?? is there any way taht i could reduce significantly the ''outside'' bass that my Iso cab is doing?
Old 15th September 2011
  #3
b0b
Gear Maniac
 

Just a few thoughts... I have been thinking of building an isocab myself and I have researched different designs. I’m in no stretch of the word an expert on this so please keep that in mind.
As you mentioned, you have a ported box. To my knowledge these ports will work as bass reflex ports. That could be one reason for the bass you hear.
The other issue I would assume is that your over driven level is much louder than your clean level. That’s why when you play with the clean channel you don’t have a problem.
The only easy solution you could try would be to close the ports. Otherwise you just have to turn the amp down.

The next step is to build an additional box to put your isocab in to further reduce the sound level of the speaker.
Old 15th September 2011
  #4
Gear Maniac
 
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what do you mean buy ''ports'' sorry my main language is french. even i'm i'm pretty good with english, i dont know what that means
Old 16th September 2011
  #5
Old 16th September 2011
  #6
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gullfo's Avatar
 

agreed, you built yourself a bass reflex enclosure. you need to seal it and it needs more mass all around plus you should decouple it from the floor.
Old 16th September 2011
  #7
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so, the only thing i need to do is add more mass ?? i was thinking of putting plywood all over the SONOpan to make that kinda ''box inside a box''. the iso cab is already lifted from the floor with some casters. sorry if i misunderstood what you said but i'm just trying to learn loll.

whats is the spesific thing i need to do first
Old 17th September 2011
  #8
Gear Head
 
tonedimension's Avatar
 

My experience with tone-sucking iso-boxes and small booths has shown the problem to be the fact that they were sealed. This created a pressure issue that made for some very odd guitar tone at higher volume levels. I had reasonable success with lower volume clean tones, but that isn't really what I needed the box/booth for in the first place. Porting as you described is not the answer because, as others have pointed out, you create a bass-reflex enclosure. Check out Rivera: The Definition of Tone and read the description to get an idea what you might do to alleviate your pressure issue. The text doesn't tell you exactly how to do it, but describes his approach. Also check out Rivera Silent Sister Iso cab explained by Paul Rivera - YouTube for Paul talking about the box. The whole idea is to get something approaching more natural tone and you simply cannot do that in a completely sealed box.

Believe me, I've suffered my way down this road before and am just trying to help. Good luck with the box. It looks like you've done a really nice job on the construction, BTW.
Old 19th September 2011
  #9
Gear Maniac
 
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the thing is that the sound is really attenuated, it could be more but my main problem is bass taht we can hear/feel outside of the box taht gets a little bit annoying. tomorrow i'll go out and buy some plywood and put it everywhere inside so my SONOpan will be between a layer of mdf and plywood. i'll put some ''silicone sealant'' so that everything glues together. i'll put some screws too so nothing will move. is there something else appart from that that i should really do to ''Enchance'' the quality/sound proofing of my iso cab?

thanks
Old 19th September 2011
  #10
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you can try the sonopan and see if that does it. typically you need the mass and rigidity plus the decoupling to really prevent the LF from radiating. per the previous poster - the tone will definitely be different... could be why a lot of people either use plug-ins or rent some time in a studio to re-amp the tracks...
Old 19th September 2011
  #11
Gear Maniac
 
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i already have 2 layers of SONOpan (1 layers equals 3 inch of Roxul Safe N' Sound) so i doubled it. not i'll put some plywood screwed to the mdf with the SONOpan in between. i heard that i shouldn't put my ''walls'' inside the box like i dont know how to say it but ''straight''. sorry i dont know what's the right word for that lol. instead of putting each wall facing each other, i should put it in a different way so it's not sounding like a box
Old 19th September 2011
  #12
b0b
Gear Maniac
 

Again, I'm repeating stuff I have read but which make sense to me...

In such a small space, parallel walls aren't your main problem. To my knowledge walls are built at an angle to reduce flutter echo and the absorbing material should take care of that anyway.

I found some good info here

Guitar Speaker Isolation Cabinet Help - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com

According to the guy in that thread (who has built IsoCabs commercially) the main thing is to get as much absorption as possible. That would mean, do not cover your SONOpan (have SONOpan between MDF and polywood) if that means that there would be no bare SONOpan at the centre.

I have seen many builds where there was an extra larger box to fit the IsoCab in when more isolation was required.
Old 19th September 2011
  #13
Gear Head
 
tonedimension's Avatar
 

Are you happy with the overall recorded tone that you get from this cabinet? With a ported design you will have some significant sound level outside the box. If you get 20-30db reduction, with good tone, I think that would be great. For example, 100db inside may still leave you 70 to 80db on the outside. If that works for you then it's great.

Thoughts for improvement? Your box looks really well thought out and and built (I checked out all the pix. Again, very well done) but here goes. Eliminate the parallel walls, as in the Rivera cabinet, to help with standing waves. I realize this might not seem like such a big deal, but... Also, is the ported area lined with sonopan? If not, I think it should be. You might experiment with the baffle/port area to see if any improvements are possible. Things like size, shape, etc. can make a difference.

I read your comment about adding plywood and perhaps misinterprested your plan. I'm not sure I would sandwich the sonopan between mdf and plywood. I think I'd rather have the absorbent exposed directly to the sound. Introducing reflective surfaces might not give you what you want. If I misinterpreted your statement, please disregard my last one.

I agree with gullfo about the plugins and re-amping. I have had to work in a space where tracking with di and plugs were required and we re-amped later (in my studio) with excellent results. Many of my clients track this way and bring tracks to re-amp. I think this is becoming more commonplace as more people track at home or places where high volume levels are an issue. Booking some studio time to record guitar tracks also has some great benefits like room, amp and mic options.

As always, just my opinions and just meant to help. I wish you the very best of luck with the cabinet.
Old 19th September 2011
  #14
Gear Maniac
 
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thanks for all y our replies. i think i'm going to add the plywood outside of the mdf and construct like a box outside of my actual box. the only thing that i dont undersstand is the ''ported'' thing. sorry french's my main language. do you mean the kinda ''false bottom'' that i did with the two 1/4'' holes i did it the bottom ? this was made so the air can circulate a little bit better.
Old 20th September 2011
  #15
Gear Head
 
tonedimension's Avatar
 

Yes. BTW, the "false bottom" was an excellent idea and definitely relieves the pressure. I would definitely line that area with absorbent if it isn't already. I think that will also help some.

I think when we refer to ports, we are talking about the holes to the outside. I guess my comment was really directed to both of those so sorry for the confusion. I was thinking that length of the false bottom or baffle area combined with the actual size/shape of the holes might be something to consider. I'm not sure you need to construct a box-within-a-box unless you are really concerned with the sound level that still remains. Perhaps just a modification to the port area? Something like an additional baffle or just lengthen the existing baffle/false bottom? Or add some internals to the baffle similar to an acoustic muffler used in HVAC systems. Just thinking...
Old 20th September 2011
  #16
Gear Head
 
tonedimension's Avatar
 

Just thinking, is the area behind the speaker sealed or is it open to the ported area? I couldn't really tell from your pix.
Old 20th September 2011
  #17
Gear Maniac
 
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the area behind the spaeker is all closed and i didnt put sonopan on the bottom yet. and by the way, that false bottom is almost as long as the actual bottom. 1 or 2 inch i think shorter i think
Old 20th September 2011
  #18
Gear Head
 
tonedimension's Avatar
 

I'm not sure modifying the box to open the area behind the speaker would be worth doing. Perhaps a little sonopan in the bottom area might help. My concern there would be constricting the flow since it looks like the false bottom has a height of just a couple inches. With 1" material you'll be taking up half of the volume of that space. If you have a few pieces I think it would be worth a shot to put a piece on the bottom just to test the effect.

At some point, you will have to decide if the box meets your needs and whether or not you can live with any minor issues it may have. For me, if I'm getting a good sounding track and 20-30db reduction in volume, I think I'm pretty happy even with a little woof on the outside. As long as that woof doesn't make it to the track. Which begs the question, have you tried recording with it yet?
Old 20th September 2011
  #19
Gear Maniac
 
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yeah i tried and the funny part about it is that i need to put more bass on my Mesa head loll at least with an SM57. With a MD421 it sounds a little bit more bassy loll
Old 20th September 2011
  #20
Gear Head
 
tonedimension's Avatar
 

Where are you placing the mic?
Old 20th September 2011
  #21
Gear Maniac
 
Vince Latulippe's Avatar
 

a little bit to the right of the cone, not directly on the cone.
Old 21st September 2011
  #22
Gear Head
 
tonedimension's Avatar
 

I think at this point you are down to experimentation and minor tweaks (mic placement and maybe some additional cab treatment). Best of luck with the box. I hope you get the sounds you are after and use it to make lots of great music!
Old 21st September 2011
  #23
Gear Maniac
 
Vince Latulippe's Avatar
 

what do you meant by ''cab treatment''
Old 21st September 2011
  #24
Gear Head
 
tonedimension's Avatar
 

Just referring to the possibility of adding some absorbent to the baffle or false-bottom area. Nothing major.
Old 25th September 2011
  #25
Gear Maniac
 
Vince Latulippe's Avatar
 

i made a move all by myself lolll, i took off all the SONOpan (insulation) and decided to put a layer of 5/8'' plywood over the mdf (by the inside) and replace the insulation on the plywood. after some testing, it's still really bassy. but i came to the conclusion that all of the bass is coming from the back of the speaker cuz when i put my hand in the front part, i can barely feel the cab shaking. if i put it on the back part, it shakes like hell. and i found taht bass is coming from the bottom so i think that i'll either fill the holes that i drilled to let the air circulate OR add a plywood to the exterior of the mdf + some sonopan between the mdf and plywood.

any other ideas ??
Old 26th September 2011
  #26
Gear Head
 
tonedimension's Avatar
 

Like I said before, my experience with sealed boxes were completely unsatisfying and frustrating. I just couldn't get the tone I wanted. the amp and mic were not able to work the same way they did in a room. Given that, I'd never consider a sealed iso box as an option for getting tone. That's just me. I know there are folks that do it, but it has never worked for me.

So, what would I suggest? If I were determined to try and make the iso box work, I'd consider revisiting the description of the Rivera design on their site. From what I have heard, their box overcomes most (perhaps all) the shortcomings of the traditional, sealed iso box design. If it were me, I'd try and emulate (re: reverse engineer) their design. I think there are several discussions of iso boxes here on gearslutz as well. Basically, more R&D.

I did see another video with this cat comparing the Demeter box and the Rivera. Rivera Silent Sister Vs Demeter by Scott Whyte using Van Halen riffs - YouTube
To me, the Rivera box sounded pretty natural as far as I could tell. The Demeter wan't the worst I've heard, in fact it was better than most, but still demonstrated what I dislike about iso boxen in general. That is, they don't sound natural. The Rivera was much better to my ears. Take a listen and see what you think. Listen to the guys summary at the end.

If all else fails, consider tracking direct and using plugins and then re-amping later. It may not be your preferred solution, but it might be the most tonally gratifying.
Old 26th September 2011
  #27
Gear Maniac
 
Vince Latulippe's Avatar
 

i really don't know what i could do more. Should i drill a hole in the ''back part'' to the ''false bottom'' so the air can go out cuz as of right now, nothing in the back is coming out. tonight i'm gonna add the plywood to the back part since i only added some on the front. and maybe later i'll add plywood on all the exterior. so it'll be from the outside Plywood,Mdf,Plywood, SonoPAN (2 layers).
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