'Perceive' Contruction Diary

[ShinOBIWAN]

Originally posted by ScottG
To me the real complexity isn't the cabinet build, but rather the cabinet finishing (..black laquer seems like such a simple yet elegant finish.. elegant it is, simple it isn't).

In any event, if Shin' wants to proceed with this design I'll try to be here to help-out. If he wants to dump-it in favor of somthing else, then thats cool too. Either way, I just hope that he gets the sound he is looking for (..or even better than what he presently "perceives" possible).

The finishing is by far the most time consuming but its the most rewarding and fun, Veneering is relativeily easy compared to a good spray job, prepping the cabinets takes weeks alone with MDF. Personally I find construction very easy. With each design I like to push the envelope of what I did last time around.

What Scott proposes is quite simple(in construction terms) but time consuming. Should be good fun!

I love just experimenting and playing around with different effects by mixing and matching paints.







Sometimes it does go wrong and cost you big:

[ScottG]

Originally posted by soongsc


How do the results of this "formula" show up in listening tests and measured data?

My test setup hasn't been what it was since I moved from normal computer to a laptop.. not really sure what is wrong - the nearfield measurements in particular are @@@@. (..and yes, I am using an outboard full duplex sound "card" - which seems to register fine after compensation.) So , there is no measured data. However if you go back and read what I've written you could probably guess how it will show-up on a CSD plot.

As for listening.. its sort of like having a dipole but with much better dynamics with better "tone" (i.e. its less "thin" sounding). And when comparing the two I was playing with a Behringer digital eq. - so for the most part level matching wasn't an issue, though output level was quite low. (But if you don't know what a dipole is like in this range.. then lets shift perspective.)

In comparison to either sealed or bass reflex - the sound is "free" from the box, or rather direct sound from instruments, singers, etc. - don't seem to "crowd-up" close the the speakers any more. Additionally, there is FAR greater "transparency" or "intellegibility". Lower midrange upper bass is subjectivly "bleedingly" fast. On the other hand though bass "slam" is considerably reduced, but tonally FAR superior (i.e. no one-note syndrom).

Now I will say that there IS a better method than I have described, but it isn't viable for Shin' - its a LOT more complex and a LOT larger

[ShinOBIWAN]

Hi Scott,

I'm interested to hear your thoughts on potential improvements to make to the mid treble enclosure.

Both the ATC and SS have no rear wave as such but is my cabinet actually doing them justice?

Would dipole be better? Any suggestions on decoupling both the ATC and SS from the baffle. Actually any advice you could offer would be appreciated.

Thanks

[ScottG]

Hey Shin',

I'm still partial to the multi-color, but have you considered a veneer with a french polish finish? Its something I think about now after looking at this thread:

Does anybody know how to get this finish?

I also like Jim Salk's finishes:

http://www.salksound.com/gallery-se.html

and Duevel's:

http://www.cd-konzert.com/Produkte/Ebellaluna.htm

http://www.cd-konzert.com/Produkte/Ejupiter.htm

I really like the combination of black laquer with that Mappa Burl. I could easily see your mid treble enclosure in black laquer with the mid-bass cabinet top's and bottoms in black laquer and the sides wraped in the Mappa Burl with a french polish finish. ..Well, thats just my taste (or lack thereof).

[ShinOBIWAN]

Cheers Scott,

I'm on the side of the more high tech and lets say lets wife friendly finishes. So nearly everything I build is sprayed. Veneering does look great when its done by a proper craftsman, so thats why I avoid it Its one of those things that's easy to do but hard to master.

Actually when I asked for your opinion on the sats, it was more from a SQ perspective rather than any aesthetic considerations.

I've grown to value your advice over the course of this project and would be interested to hear on any potential ways to extract more from the ATC and SS through cabinet design.

[ScottG]

Originally posted by ShinOBIWAN
Hi Scott,

I'm interested to hear your thoughts on potential improvements to make to the mid treble enclosure.

Both the ATC and SS have no rear wave as such but is my cabinet actually doing them justice?

Would dipole be better? Any suggestions on decoupling both the ATC and SS from the baffle. Actually any advice you could offer would be appreciated.

Thanks

(there was just a "time-lag" thing going there with posts)

I think your good there.. You could reap a minor gain from casting the whole thing in concrete - but I don't think it will be worth it (truely a diminishing return thing). If there are any hollow recesses just load them with the standard ultra fine sand and lead shot.

Now the coupling to the midbass cabinet could be improved, perhaps something like what Verity Audio does (i.e. micrsorb and granite) - but if we stick to a seperated double wall construction on the speaker (and the top panel in particular) and the mid-treble cab. is fairly massive, then you won't need it.

IF, I repeat IF the force of the midrange is causing cabinet vibrations that would disturb the tweeter AND the tweeter's force doesn't cause the tweeter any motion problems, then you could use some microsorb to decouple the tweeter from the cabinet. The best way to determine this is remove the tweeter from the cabinet and play some music with a punchy character in the midranges bandwidth while touching the cabinet where the tweeter normally resides. If you feel vibrations here then play some music with the tweeter in your hand - if you DON'T feel vibrations from the tweeter then consider using the microsorb. (ok that prob. sounds a little stupid.. LOL, make sure the pointy end is up when the tweeter is in your hand..)

Long story short - No (..prob.).

As for the midbass:

Actually a Dipole is inferior as long as you get a handle on room acoustic deviations (and you have a REALLY good enclosure).

[ShinOBIWAN]

As always Scott, thanks. Once the new sats are done I'll be sure to try out what you've suggested.

I actually started on contruction yesterday, so I'll post some pics tommorow.

I have some ideas floating arount for the baffle but I want to consider weight at this time so I'll try it out, see what it weighs like and if its doable I'll see what you think.

[soongsc]

Originally posted by ScottG


My test setup hasn't been what it was since I moved from normal computer to a laptop.. not really sure what is wrong - the nearfield measurements in particular are @@@@. (..and yes, I am using an outboard full duplex sound "card" - which seems to register fine after compensation.) So , there is no measured data. However if you go back and read what I've written you could probably guess how it will show-up on a CSD plot.

As for listening.. its sort of like having a dipole but with much better dynamics with better "tone" (i.e. its less "thin" sounding). And when comparing the two I was playing with a Behringer digital eq. - so for the most part level matching wasn't an issue, though output level was quite low. (But if you don't know what a dipole is like in this range.. then lets shift perspective.)

In comparison to either sealed or bass reflex - the sound is "free" from the box, or rather direct sound from instruments, singers, etc. - don't seem to "crowd-up" close the the speakers any more. Additionally, there is FAR greater "transparency" or "intellegibility". Lower midrange upper bass is subjectivly "bleedingly" fast. On the other hand though bass "slam" is considerably reduced, but tonally FAR superior (i.e. no one-note syndrom).

Now I will say that there IS a better method than I have described, but it isn't viable for Shin' - its a LOT more complex and a LOT larger

I already have openess of sound a freedom from speakers just in simple setups, but in measurements I see dips in many wide range drivers around 9K~14K range, which varies significantly from manufacturer data. I tend to think it's reflection from the frame where the spider is located.

For bass application, the "formula" seems like a valid application as long as the lenth of the straws are such that the driver is operating significantly lower than their resonant frequencies. I wonder whether paper honeycomb can be used.

The NASA coating sounds interesting, are there any technical specifications for this coating?

[ShinOBIWAN]

Starting to get the impetus again So pictures so far:







Not really much to show but I only spent a few hours on them, everything has to start somewhere I guess I've decided to keep the old cabinets and will maybe buy another set of ATC's and SS perhaps press them into surround or center channel service later on.

Scott what do you think of this:



What your looking at is the front baffle of the bass cabinet. 3" thick and I plan to bore the hole right the way through this and then create a further 6" lamination of MDF in the shape of a tube. So all in its 9" in depth. The irregular cabinet shape should help minimise standing waves.

This should explain better:



The only downside is that the bass cabinet is going to massively heavy. Double thickness walls throughout with extensive bracing. I'm guiessing at around 60kg each as a minimum.

Would you care to comment on the aperiodic vent placement in this shaped cabinet.

Trying to order the Supravox's from somewhere in Europe but no one wants to sell the damn things to an englishman

I've managed to track down a UK distributor but after numerous phone calls all I get is no answer - on holday?

For others interested in Supravox in the UK this is our distributor:

Real hi-fi
35 Water Drive
Standish
Lancashire
WN6 0EH
UK

Tel: +44 870 9096777
Fax: +44 870 9096776
e-mail: realhi-fi@blueyonder.co.uk
Net: www.realhi-fi.com

I've waited for 6 months already so the wait for a couple of drivers isn't going a problem. It will hold the construction up a little though since I don't have diameter (inner and outer) Does anyone know these or could measure them for me please?

Cheers
Ant

[ShinOBIWAN]

Scott I'm a little concerned about the mms on the 215 GMF - 10g! You sure that's right? According to the Supravox website, yes, but I'm wondering just how well defined the bass will be with such a low mass cone.
Surely the stiffness isn't upto the like of the Seas, so will I be looking at a loss in definition on the low bass(40-80hz) with an edge in transparency through the mid to upper bass?

And are you sure the 'vox will be good to go sealed with aperiodic? I'm somewhat weary of sealed after the Seas let down.

Cheers.