John Sayers' Recording Studio Design Forum Archive

I was relieved to see that other people have attempted to soffit mount their V8s with success.

So it's now my turn (until I can afford some MiniMain 12s )...

I have a picture of the back of the V8 which are here: http://www.pbase.com/riadanza/stage_5

What do I need to make these settings to get the best results?

Then, I'll need to get some specifics about the soffit design because even after reading all the threads I'm still a little uncertain.

Thank you much!
Robert

It's a front ported speaker, so you shouldn't have any big issues.

The two things I recommend are a Baffle Step Decompensation Filter and my decupled soffit design. Dbluefield has built a nice expel of it, posted on John's studios under construction page. http://www.johnlsayers.com/Studio/Pages/Bluefield1.htm

Thomas

Thomas,

Thanks for the reply... I'll decouple the speaker shelf from the outside frame, that's no problem since I'm just starting to work on the soffits now.

I don't have the energy or time to build the decompensation filter, how much do you sell them for?

Thanks again,
Rob

Thomas,

I have read a few debates on this board on whether or not to have the front soffits reflective or have 703 covered in cloth. I was thinking of slot resonating under the speakers - some reflective, some absorbing. Is this advisable?

Thanks again,
Robert

The SC2 hasn't been officially released yet, but the price will be around $1200-$1300.

As far as the soffit baffle goes, it should always be reflective below the "baffle step" frequency. This frequency, however, is a moving target depending on how far away from the speaker you get.

You can see the effect of flush mounting a nearfield with my Wall Bounce Calculator. Set D=0, L=any value, W=25, and F3=1. Notice the +6dB step in the low end response. This occurs because low frequency energy, that would have otherwise wrapped around and radiated toward the back of the speaker cabinet in a freestanding situation, is now forced towards the front the soffit baffle. We use the baffle step decompensation filter to flatten this response out. But this new response depends on the fact that the baffle is reflective.

However, we can see for our W=25cm example, if the soffit baffle is absorptive above about 4kHz, it will make little difference in the response. This is because the speaker baffle itself is doing all the work at those short wavelengths and the soffit has little impact. Now, let's image that the soffit baffle is just an extension of the speaker baffle (which it is). If we make W=50cm, we see that soffit baffle absorption above 2kHz will have little effect on the response. If we make W=100cm, we see that soffit baffle absorption above 1kHz will have little effect. And so on.

So the soffit baffle can get more absorptive at lower frequencies the further you radiate out from the center of the speaker; because the areas closer to the speaker have already done their job of forcing the bulk of the shorter wavelengths to radiate in the forward hemisphere. Make sense?

Having said all this, I still like John's design with a reflective soffit and high frequency absorption underneath to reduce secondary reflections from the desk.

Thomas

Yes, that makes sense.

.."Having said all this, I still like John's design with a reflective soffit and high frequency absorption underneath to reduce secondary reflections from the desk. "

I'm assuming you are referring to the opening at the bottom of the soffit and the hanging trap inside?

Do you have an expected date of release for the SC2?

Here are my results from the wall bounce calculator...
My values were: D=0, L=241.3, W=27.95, F=47Hz (this can be adusted +/- 3db but I'm using the nuetral setting here.)
Wall ab. Coef: .43, .78, .9, .97, .97, 1



-Rob

Thomas,

Would be able to help me understand what the graph in my above post represents and what I would do with that information?

Thank you!!
Rob

Yes, this is the baffle step I was referring to.

You've input the cabinet width of your V8's and set the wall distance to zero for flush mounting. Now the soffit wall is forcing all of the low frequency energy into the forward hemisphere; energy that would have otherwise radiated omni directionally in a freestanding situation. This causes a 6dB boost in the low end. If the speaker f3 were very low, let's say 1Hz, you would see a simple +6dB low-shelf curve (try plugging 1Hz in to see). However, the f3 of your speaker is 47Hz, so you don't see the full shelf curve. The rising shelf is convoluted with the falling speaker response. Nonetheless, you still need an appropriate -6dB low shelf filter to counteract the effect.

Thomas

Thomas thanks for the clarification it's much appreciated.