What DIY sub to match with Maggies for music??? (1 Viewer)

[Stephen White]

So if you fill it the Q gets lower??? From looking at cabinet designs the Q gets lower as the volume gets bigger so why would fill make the Q lower???? It would be taking away the volume????

Wait, is "Qtc" the same as "Q"??????

If this is the case I guess I could use the .707 cabinet and just fill it to lower the Q......is that right

That doesnt make any sence to me....can someone explain how the "Q" works and give me a good link about it.

Thanks,
STEPHEN

 

[Jack Gilvey]

Link Removed

 

[Stephen White]

Jack, thanks for the info!!! One the last paragraph of that link he says stuffing becomes less effective the larger the box size. He also said to stuff boxes under 3 cubic feet, mine is going to be around 5 cubic feet so would stuffing be pointless???

Also he talked about the larger the box the more bass you get. Here is my question, what exactly is "Q" and how does it affect the sound? My understanding is the lower the Q(which from what I've seen means a bigger box) the more musical the sub is. The higher the Q the better it is for HT and SPL. Is this correct or is the box size really just going to change SPL???

Thanks for all the info guys, I'm soaking it all it.....or trying at least haha

 

[AndersP]

Hi Steven.
You´re showing all the signs of a very fast learner. It took me much longer to learn what you have so far.

Q for a closed box = box Q = Qtc is a way of describing the shape of the bass rolloff for different combinations of drivers and boxes. Qtc is driver specific meaning different driver in same box gives another Qtc. Vance Dickason explains this and other things very well in his " loudspeaker design cookbook ".

One thing bugs me reading this thread; What about those unused 15´drivers you had lying around? What was wrong with them? I remember you thought they played " slow " in the boxes they are in now. Maybe they are a " high Qtc " - alignment, explaining their slowliness or even worse: what if the Carver amp has a few pots that can be twisted for adjustment etc?

I´m just saying that I think there could just be good things coming out of playing around with what you´ve got for the moment.

OK - now you can kill me.
\Anders

 

[Jack Gilvey]

http://xsspl.tripod.com/Audio/SealHelp.htm
http://www.audiomobileinc.com/subs101.htm
http://www.nightstormer.com/def.htm#Q
http://www.nightstormer.com/dilemma.htm

 

[Stephen White]

Yea, after reading all this info on how the box and driver interact to create the sound I was kinda thinking about building a box for the 15" tempest but try using my 15" speakers that I already have laying around to see how they sound. They are currently mounted in a enclosure that is sealed and prob 18x18x5 which because of the depth isnt even a cubic foot!!!! No wonder they are so boomy sounding, surely that would make for a VERY high Q. I might actually make 2 of these end table boxes if the first one turns out real nice and I can use my current equip with good results. I can put one on each end of the couch.

Someone mentioned about possible bass boost or something being on my current amps....does anyone know how i can tell? Would I be able to tell just by looking at it? Is there something to look for???

If I end up using my current speakers and electronics that would be nice, I could make some damn nice cabinet/endtables for $400!!!!

STEPHEN

 

[Jack Gilvey]

Unless you can test the drivers/amp, using them is a crapshoot at best. I'd build the box you want, try the driver and amp in it. If it's great...great! If not, you can get a Tempest/Shiva. The driver was designed to do what it does in the box it's in.

 

[AndersP]

I will now have to respectfully object. My deal is:

1. Get someone to measure the drivers for TS - parameters and give you a box volume for a Qtc = 0.5 alignment. Maybe someone here at the forum lives near you and could do it for a warm meal or something

2. Try your new design with the Carver amp - what is there to lose? The problem is that the carver amp can have not to tamper with - internal filtering designed for the old box - driver design. You may get hard to imagine results with it, but you should not be able to brake anything.

We were referring to adjustmentknobs near the power intake. If therte are no such adjustment possibillities dont go further; next step being tweaking the inside of the amp and the danger of ruining it, or having someone doing it for you and get yourself a fat bill.

\Anders

 

[Stephen White]

Are there any other good drivers like the Shiva/Tempest that are designed for the diy guys in mind??? I might try mine out in the cabinet and if it doesnt sound good swap it for the Tempest.

I figured since mine is currently in a very small box and is boomy it might open up and sound better in a box like what the tempest would sound good in. I'm thinking that in a one foot box the Q of my sub is prob 1.0 or higher and if I was to put it in a larger box that would go down. If I build a box thats .577 with the tempest would it not be the same .577 with any driver.

I guess what your saying is that different drivers sound better or worse with different Q's...is that what your saying. Like maybe my speaker was designed for a Q of .9 - 1.2 and if I put it in a box with a Q of .577 its going to soud bad.....is that what you were saying???

Thanks

 

[Jack Gilvey]

I will now have to respectfully object. My deal is:

Object? I think we're in agreement, I said unless you can get the driver tested, it'd be a crapshoot...see? If you can get the specs for the driver, then you can get the "righ"t box for it (I can almost guarantee better results with a Tempest, though). Like I said, try the amp too just for fun.

 

[Stephen White]

AndersP - Yea my speakers that I might be using for parts had a 15" sub with the Carver amp and also a crossover with a knob for adjustment. It also had all the necessary inputs. I figured I could take all that out and mount it on the new sub. The filtering points and all that I have no idea about.

STEPHEN

 

[Jack Gilvey]

Stephen,
There's no way to tell what the Qtc of your sub is without the specs of the driver, specifically Qts and Vas.The small box itself tells nothing about the Qtc. There could also be circuitry in the amp to change the rolloff and hence the Qtc...there's too much not known to guess at (and why these "replacement box/driver" threads almost always end with "don't bother...")

 

[Stephen White]

If I were to pull the driver out of the box would the be anything on the back of the driver like some kind of specs or something that might give me a clue or starting point???

Thanks,

 

[Brian Bunge]

Stephen,

No, there wouldn't be any specs. At the most, it would say whether it was a 4 ohm or 8 ohm driver, but that would be it. You'd be better off just buying a Tempest (or Dayton DVC 15") and a plate amp and design for the Qtc that you want.

Brian

 

[AndersP]

Goddamm boys, hold your horses, I´m writing here!

Jack: sorry, I misunderstood you completely. English is not my first language........

Steven: Listen to Jack. The drivers must be measured ( or in worst case: you must get your hands on a spec sheet for this driver in hand ) This is for a. finding out the old Q ( as if you really wanted to know - it is to high!) and b. to find the new boxvolume ( targeted at say Q = 0.5 )

Now tell me what inputs and controls you have on the backpanel. With controls ( fex crossover ), what are the max and min settings?

 

[Brian Bunge]

Anders,

Jack: sorry, I misunderstood you completely. English is not my first language........

Nor Jack's as he's from Jersey!

 

[Jack Gilvey]

 

[AndersP]

Ha, ha, that was really funny to me, but if that is the case, I think he makes very much out of it!

 

[Stephen White]

AndersP - The back of the speaker has regualar speaker wire and interconnect type connections. It also has a on/off/auto switch and an adjustment knob. The only thing about the adjustment know is now that i think about it I dont think it changes the crossover point but rather the volume. I havent used the speakers in over a year so I could be worong.

So you guys pretty much think I should not worry about my stuff and just get the new Tempest and amp. Dan with Adire recommended the AVA250 plate amp ($179) for the Tempest.

I think it would still all fit in my budget, I'd have the $150 for the Tempest, $180 for the amp, that comes to $330 + shipping so I'll just say $350. That leaves $150 for the cabinet materials.

Is that pretty much what you guys think i should do??? have you listened to the tempest? How is it compared to the Shiva???

Thanks,

 

[Jack Gilvey]

I'll have you know, Anders, that I'm a proud 1/4 Norwegian.

I think it would still all fit in my budget, I'd have the $150 for the Tempest, $180 for the amp, that comes to $330 + shipping so I'll just say $350. That leaves $150 for the cabinet materials.
Is that pretty much what you guys think i should do??? have you listened to the tempest? How is it compared to the Shiva???

Back to square one. Yes, that's what I'd do. The Tempest sounds the same as Shiva, just louder.