DIY Gobos between Bass Amp and Drums

[mikoo69]

I am looking for a construction plan to build my own portable/moveable gobos.

I am doing all live recording and I want to build some gobos to place between the drumset and the bass amp, to prevent bleed from the bass into the drum mics and overheads.

We are recording bands live, setup like they would on stage (bass amp to one side of the drums, rhythm guitar next to bass amp, lead guitar to the other side of the drums). I was thinking of building 2 large gobos to put on both sides of the drums to block bleed, as well as using U-Haul Packing Blankets to block the guitar amps as well (i hear the U-Haul blankets are great for Mid-HF isolation, such as guitar amps, as well as to use while cutting vocals, behind the vocalist).

I'm ready to build, I just need plans. Low budget so as cheap as possible, while still doing the job.

Thank you.

[nosebleedaudio]

Easy, I use 1 by 8 Or 1 by 10 to build a 4' by 4' square with a sheet of 3/4 plywood in the middle..703 on both sides, fabric on top of the 703..done..
Wheels on the bottom with outriggers for stability, say around 4" on both sides..

[mikoo69]

4x4 tall enough? we want to block the bass amp from the OHs (ampeg 8x10 cabinet). I was assuming the gobos would be at least as tall as the ampeg.

[Szejna]

Originally Posted by mikoo69

4x4 tall enough? we want to block the bass amp from the OHs (ampeg 8x10 cabinet). I was assuming the gobos would be at least as tall as the ampeg.

The classic ampeg svt 8X10 is exactly 4 feet tall so it should be sufficient.

[DanDan]

A Gobo will block very very little bass.
It takes masses of mass and huge dimensions to do that.
The Low E wavelength is about 25 feet long, it won't even see a 4 ft barrier.

I doubt very much that blankets will have any effect at MF, and only slight at HF.

Sorry, but isolation ain't easy.

Here's the plans for the Abbey Road Gobos which originated at the BBC.
http://lib.store.yahoo.net/lib/merce...udio/abbey.pdf

Try to minimise the gap at the floor, or even include a draft excluder or such.

DD

[mikoo69]

going to build some today. the plan is to build two 8' tall x 4' wide x 4" deep gobos to put on both sides of the drumset separating it from the bass amp and guitar amp on the other side. then to build another 4' tall x 2' wide x 4" deep gobo to put between the bass amp and the second guitar amp.

were gonna keep it simple...build the frames out of cheap ply/pine, get some cheap "breatheable" fabric, and then 20 sheets of 703 (2" thick 2'x'4').

then we are going to get 2 uhaul packing blankets to put behind the drums, and also will use them as a vocal booth with the 2 large gobos....for mixing we can put the large gobos behind the monitors, and the uhaul blankets at reflection points on the wall.

how does this plan sound? will the 4" thick gobos help keep some bass out of the drum mics and just help us get beter drum sounds with the entire band playing in the same room?

[DanDan]

Gobos can be absorping, blocking, even diffusing, depending on the construction. To make any attempt at blocking bass you need a heavy sheet of material. Sheetrock or MDF. 703 and fabric facing to absorb HF.
DD

[mikoo69]

so is there a way to use some MDF instead of 703? for instance, instead of 4" of 703, maybe 1" of MDF on either side and 2" thick 703 in the center?

[DanDan]

703 does not in itself block sound. You could easily hold a conversation through it. If you were a bit strange...;-)
The MDF or such is to block. Thicker the better. I am sure you can visualise a foot thick of MDF will block plenty.
4 inches of 703 on the surface will stop the MDF reflecting back nasty HF and MF extremely early reflections.

[mikoo69]

thanks dan. so how would you recommend altering my plans to include MDF? I don't need it to be completely dead sounding. Just trying to get a bit more separation in the room, mainly for the drum overhead image, as the amps sound really awesome and are close miked.

[DanDan]

Sheet of MDF or sandwich of ply and sheetrock. 703 attached to one side.
Face the 703 side in towards the drums, the hard side toward the amps.
Over vice versa if you like the sound the reflections add to the drum tone.
DD

[jwl]

Agreed completely with DanDan. Another thing you can add to the inside of the gobo is sheetrock/drywall, which gives you a lot of mass per dollar.

I once built some gobos that worked well, layered as follows:

cloth : fiberglass : drywall : MDF : drywall : fiberglass : cloth

[Rentzen]

Originally Posted by DanDan

703 does not in itself block sound. You could easily hold a conversation through it. If you were a bit strange...;-)

Funny that you should mention it. This is the ONLY kind of conversation I hold. It is especially useful when trying to pick up the ladies. In fact, I've now made a mask (youtube tutorial will follow soon)!

[DanDan]

I'll bet you get very absorbed in those conversations....

DD

[recordinghopkins]

I have so many questions for the OP!

Are you recording this way to make use of an empty nightclub during the day, or are you recording this way by design, as a matter of principle, to approximate the energy of a live performance as it would happen on stage?

Perhaps you just don't have room for isolated spaces, but you do have the channel count to track the whole band at once. How are you handling foldback?

How big is the room?

Is the goal a "Studio" or "Live" aesthetic?

Are you overdubbing vocals?



I'm a skeptic that you will be able to do much to control bass bleed with gobos. If it's a live aesthetic you're after, gobo for reflections and high freq bleed, and high pass the overheads. How much of the bottom two or three octaves do you really need overhead anyway? Or do what you can to make the room sound as good as possible, and embrace the bleed. Either way, make good use of the high pass all around. Instant tighter bass track.

If it's a more "studio" aesthetic you're after, DI the bass or move the speaker cabs into the next room to get the isolation you really want.

[mikoo69]

just an update. we did the sessions with no gobos and it came out great. there was a lot of HPF used in the mix, but overall, the bass wasn't really a problem for bleed. the worst problem was my guitar amp being too loud in the drum overheads, since I was using Coles 4038s in recorderman style, and the right shoulder OH picked up way too much of my guitar....however, we managed to get the mix sounding fine! the energy was great and everything can be heard, and that's all that matters for us at this stage...they were just demos we were recording.

we are going for a live feel, having the band playing with no-one using headphones. vocals overdubbed.

we'd like to record this way again, so next time I will want to focus a bit more on isolating the guitar amps, so they can still be cranked up, but not bleed so hard into the overheads.

the biggest mistake i made - i ran a 4x12 + a 2x12, when I could have used a single 12" combo to get just as good of a guitar sound....i thought that all the speakers would represent our live sound better, but when it comes down to it, the guitars were all close miked and the results were no "bigger" than the results i get when just miking my 1x12 Deluxe Reverb combo.

would the 4x12 (hiwatt) cabinet and 2x12 (orange) cabinet work as gobos if i placed them between the combo amp and the drumset?