Vista Woofer Parameters, Ideal Replacement plus Crossover Improvements

[InterMechanico]

Okie Doke, Here goes....

For the past 6 months or so, I have been wondering about improving upon the basic design of my Vistas.

The panels are fine as they are; obviously no improvements to be found there.

The Woofers, on the other hand, could probably be improved upon. Not for higher SPLs, but for definition and clarity at lower SPLs.
The parameters given to me by ML are as follows;



Rdc 4 ohms ±5%
BL 7.0tesla m ±10%
Sd 214 cm^2 ±5%
Vas 50liter to 80liter
Mms 28gm ± 5%

It is, of course, an 8 " woofer. I haven't removed one yet to measure the opening, but will do that in due time.

Of the parameters that have been provided, I think I know the following things:

Rdc must remain constant at 4 ohms
BL- Force Factor- Not sure of this one
Sd will be limited by woofer diameter; no changing that
Vas will have to do with the enclosure volume, Vista is roughly 30 litres;
- Vas has to do with how the woofer interacts with the enclosure volume
- Lower end of range or higher end of range- Not sure which is better and with what result, and what happens if I increase this figure.
Mms- I may be wrong, but if I can reduce the Moving Mass of the woofer without sacrificing cone rigidity, it should tighten up the lower frequencies.

I'm not sure what's in there now, but I'll try to figure it out before moving forward.

Possibilities:

http://www.madisoundspeakerstore.com/approx-8-woofers/accuton-s220-6-221-8-sandwich-cone-woofer/

http://www.madisoundspeakerstore.com/approx-8-woofers/scanspeak-revelator-22w/4851t-8-woofer-paper-cone-4-ohm/

The problem is, the VAS of these two options exceeds the spec given to me by ML. Any opinions?


As far as the crossovers go, I recall a member recommending a fellow who could make improvements to stock crossovers. Can anyone recall who performs these mods?

Thankie

Julian


Look forward to doing more :rocker:

 

[|Tch0rT|]

Unless you have the measurement tools for testing T/S parameters I wouldn't really mess with it. Passive Xovers take a lot of time in testing and tweaking over and over. If you want to go through with a better woofer I'd personally just go with active crossovers and separate power amps (active bi-amping). Once my 5 year warranty is up on my EM ESL's I may go that route myself.

 

[MPS]

Are you planning in designing a new crossover? If not I would stick to options (if any) which exactly match parameters of the original and you are missing some...
RDC is pretty meaningless, look for impedance, actually you should measure it in the current enclosure and then measure your replacement driver in the same enclosure if deviation return to the beginning of my answer.

 

[InterMechanico]

Are you planning in designing a new crossover? If not I would stick to options (if any) which exactly match parameters of the original and you are missing some...
RDC is pretty meaningless, look for impedance, actually you should measure it in the current enclosure and then measure your replacement driver in the same enclosure if deviation return to the beginning of my answer.

I am ok with designing a new crossover. I know that upgrading the woofer alone would be an incomplete upgrade, probably a downgrade. The specs given to me by ML are all they have available. I will remove a woofer in the next few days to have a look. Is there anyone commercially able to design the crossover, or can I do the math myself? A link rather than an explanation would be great; I don't want to take too much time from anyone's schedule. Thanks and wish me luck!

 

[InterMechanico]

Unless you have the measurement tools for testing T/S parameters I wouldn't really mess with it. Passive Xovers take a lot of time in testing and tweaking over and over. If you want to go through with a better woofer I'd personally just go with active crossovers and separate power amps (active bi-amping). Once my 5 year warranty is up on my EM ESL's I may go that route myself.

Bi-amping has been a consideration for me for awhile. I know nothing about active crossover, other than the introduce filters before amplification and are infinitely adjustable. I'd like to stay passive on the crossovers, but like you say, I'll need to find someone in Vancouver who can do the testing and tweaking, or get some measurement tools and spend a lot of time (well spent) testing and tweaking myself.

 

[InterMechanico]

Bi-amping has been a consideration for me for awhile. I know nothing about active crossover, other than the introduce filters before amplification and are infinitely adjustable. I'd like to stay passive on the crossovers, but like you say, I'll need to find someone in Vancouver who can do the testing and tweaking, or get some measurement tools and spend a lot of time (well spent) testing and tweaking myself.

Note: Not "Tweaking Myself", but Myself doing the tweaking on the crossovers

 

[Tosh]

Go active xo on just the bass, or don't bother doing anything. Especially with the high xo point on the Vista, the difference will be dramatic. Both your ESL amp and your bass amp will be so happy, and the bass will be so clean...