VOLT 15" woofer PORTED OR TL BOX??

[domtweaker]

Is it worth building a TL box for my dual 15" Volt woofers ?

I have the ability to EQ the bass using my Marchand Bassis unit

I would like to get the most out of these great woofers

I will use them up to 400 hz

What benefits will I get from going to a TL design

The boxes for TL seem to be large


Pros and cons if anyone has used that driver or just any info please.

cheers

[bjorno]

? 3823 or 3853?

b

[Charles Darwin]

A bit like these?

http://www.pmc-speakers.com/docs/145ae357f281c6_XB3.pdf


I use a couple of 12" Volts in t/ls, work fine for me.
They go down to the low 20s without eq in room and never seem to run out of headroom, at nearly 300w they sound like with 3w only louder. I run mine up to 175Hz.

[domtweaker]

Mine are 3853 units


Ch Darwin what length and design did you use ?

Did you try them in a ported box ?

are you using the same model like mine ?

Ratio ? single or twin units per channel ?

How hard was the tuning ?

cheers

[Charles Darwin]

Mine are RV3143s.

The line is about 2m in length and narrows from about 2x Sd to Sd, single driver.
Never bothered to try them in a ported box, mostly because I had stumbled across a review of high $ subs and PMCs 15" t/l was the only one, alongside Genelecs, whose THD stayed below 10% at all times but they did not test ported Volts. I like PMCs though…

Tuning was surprisingly simple. I just lined the line around the driver with 50mm acoustic foam and filled the length with long-haired sheep wool (it was the cheapest I could find by far) at the density recommended by King which was something bizarre like 0.5lb per cubic ft or so (pain in the neck to convert that to sensible units).
Worked out fine and I never saw reason to fiddle with that.
The boxes have a volume of about 140L* and I folded the line so the terminus is more or less directly above the driver. The driver is 75cm above the floor, followed by the terminus and on top of that a 12" Tannoy DC in his own 46L cab.


*Somewhere in his work King mentions that ideally a t/l should encompass a volume very similar to a maximally extended, maximally flat ported box. This is roughly the case here.

[domtweaker]

You went with 2X sd that is a bit steep of a ratio .

Most sudgest 1.25 to sd ?

how is the bass quality and quantity ?

What slope xover are you using ?

Have you ever ran an impedance curve check ? Just to see how the speaker reacts ?

[Charles Darwin]

xover is 24dB L-R active.

Someone made off with my computer and its software so I used an old analog thingy to measure 1/3 oct and in room the speakers within 2dB from 24Hz to 20k.

[domtweaker]

I often wondered what ratio of TL PMC uses ?

Any ideas ???

[Charles Darwin]

I think it is mass loaded, judging by the size of the terminus (<Sd I seem to remember).
So far I could not convince anybody to let me open up their XB2 or 3s ;-(

Just checked and the ratio in mine is actually 1.5-1Sd.

[domtweaker]

No I dont think anyone will let us peak inside ha ha

I wonder if a sharper taper would sound better ?

1.25 - .5 SD maybe ? Any ideas ?

Is there any good sites to read about this issue ?