'Perceive v2.0' Construction Diary

[ShinOBIWAN]

Originally posted by BlackCatSound
[B]

Hehe!! someones never used Volts

Power handling: double the quoted figures and you're in the right ball park. I've run the nuts of the R3823s in my PA rig without damage. At the end of the night the grille on the cab is too hot to touch and the whole cab itself is warm. The only time I've damaged a volt is by messing around with the clip limit on an amp and asymetrically clipping it into a pair of them, bent the voice coils against the backplate. Didn't stop them working but they scratched a bit.

X-max: the quoted figure is for the truly linear portion. x-mech is about 20mm each way for the 15". They will move until the cone hits the heatsink.

Yep, Volt rate their drivers fairly conservatively. I was laughing when Bill told me about you running the Volts so hard and they still came out untouched. I doubt many drivers would have stood that sort of punishment.

Its a bit odd they've never ventured into the sub 30Hz region. I'd like to know the specs of the 12" radial PMC use.

No doubt the Volt's PMC use are bespoke stuff.

They also use a 15" version in a rather large transmission line:

http://www.pmcloudspeaker.com/xb3.html

CRT Projectors had one of these in their demo room driven by a large Bryston amp alongside IB1 speakers all around and a Barco Cine 9 CRT projector. That was a very serious system but I felt the bass was a bit much for the room size, some EQ would have definitely benefitted it. It did seem to reach low though, easily to 20hz and probably lower than that.

Hell, the IB1's alone sounded like they didn't need a sub.

[ShinOBIWAN]

Originally posted by ScottG



NOT fair! .. that is your midrange you are talking about, correct?

You know BMS Pro has some astonishing technology in that "department" and unlike everyone else they are not charging the proverbial "arm and leg".

Yep, its the mid so it is a bit deceptive.

The BMS stuff has always looked good to me, unfortunately no one deals with it over here. I looked at the Planar Neo driver earlier this year, certainly interesting.

I've never heard one but apparently the Precision Devices line of drivers is very good too.

They've got a statement 21" driver that looks like it could offer a life changing experience if you can afford the room. Tony Gee is using a pair of these!

http://www.precisiondevices.co.uk/ShowDetails.asp?id=16

[ShinOBIWAN]

Scott,

Just a quick question:

Any particular preference for driver mounting? By that I mean should I place one to the front and one to the rear to cancel out some of the forces created by the drivers or should they be both forward firing?

I'm still pretty surprised by the predicted max SPL at 20hz when using 2 drivers in an 85ltr enclosure tuned to 20hz: 114dB. Then add the other sub for another +6dB and that's 120dB. Stick these two in my room and I've found I gain around another 5-6dB at 20hz from past experience.

That's a lot of SPL with plenty of headroom, I'm guessing a small amount of EQ will be needed but it shouldl only be slight.

I completely agree with you, this should be a very dynamic performer and the distortion will be extremely low at my usual listening level of 80-90dB thanks to the masses of headroom.

I'm looking forward to this

[ScottG]

2 drivers in a 85 ltr enclosure? Change the design?

Holy cr@p! ..did you purchased 4 drivers? I was only talking about 2 (total)!

Can you get hold of your supplier and cut the order in half before he ships?

(..and here I thought the 700+ was an exageration.. I'm such a dumb@ss )

If on the other hand you actually wanted that many - let me know. You could make 4 of the things and array them so that room modes are "swamped" at almost any position. (..that would be near the center of each wall in the room.)

Often driver coupling is used to reduce even order non-linear distortion. To make it really work well you need to actually couple the drivers together frame-to-frame, then 2nd order drops like a stone. It's not terribly usefull though unless the 2nd order spectrum dominates the response in the desired passband (i.e. is 10-15 db higher then 3rd). If its near the 3rd in level then it is kind'a pointless, after all - you would in effect simply have "exposed" 3rd order distortion. The problem here is that we don't know how the B&C driver operates distortion-wise.

[BlackCatSound]

Originally posted by ShinOBIWAN
The BMS stuff has always looked good to me, unfortunately no one deals with it over here. I looked at the Planar Neo driver earlier this year, certainly interesting.

I have a source.

I'll happily collect 2 of the B&Cs from Andy for you I'm down that way later today anyway.

[Puggie]

Originally posted by ShinOBIWAN

I've never heard one but apparently the Precision Devices line of drivers is very good too.

They've got a statement 21" driver that looks like it could offer a life changing experience if you can afford the room. Tony Gee is using a pair of these!

http://www.precisiondevices.co.uk/ShowDetails.asp?id=16

I have one of those preparing to be installed in the car, hopefully it will do the business, I could knock up a home box and compare it to the ATC if you want to know how it does

[Geenius]

I'm a bit short of time at the moment, but I have decided to go for two 110 litre closed boxes driven by two Ucd-700 class-D mono-blocks.

[ShinOBIWAN]

Originally posted by ScottG
2 drivers in a 85 ltr enclosure? Change the design?

Holy cr@p! ..did you purchased 4 drivers? I was only talking about 2 (total)!

LOL

No wonder I was so impressed with the figures.

Sorted it now.

I don't have room for 4 seperate 80-odd litre enclosures dotted around the room unfortunately. I thought you meant dual drivers in each of the stereo subs since you mention 2 drivers but obviously I mistook you. That's good anyway since I've just saved a fair amount of money.

What do you think to using 2 in a each sub anyway

[ShinOBIWAN]

Originally posted by BlackCatSound


I have a source.

I'll happily collect 2 of the B&Cs from Andy for you I'm down that way later today anyway.

Hi Tom

I was told that these were special order from manufacturer and weren't in stock. Not sure if I spoke to Andy or not when I placed the order.

If he has got them then feel free to take them and give them the same punishment you gave to the Radials

Originally posted by Puggie



I have one of those preparing to be installed in the car, hopefully it will do the business, I could knock up a home box and compare it to the ATC if you want to know how it does

Hi Bill

Bit unfair

The 15" ATC would simply die, its good but I'm sure it ain't no match for that 21".

[ShinOBIWAN]

Originally posted by Geenius
I'm a bit short of time at the moment, but I have decided to go for two 110 litre closed boxes driven by two Ucd-700 class-D mono-blocks.

Hi Tony

That's smaller than I expected, I'm guessing your using some EQ to get the extension down a little?

What do they sound like sealed?

Always impressed with your plan diagrams, what software do you use for that BTW? I use CorelDraw12 for the 2d stuff but its not really suited and the scale requires you to work in mm and then convert to cm for your cutting diagram, this means half your time is spent zooming in and messing around with nodes.