Ribbon crossover at low Xover

[Tenson]

Hi,

I would like to build some speakers that use a ribbon for mid and HF range. I have a woofer in mind (the Volt B2500.1) which I want to use for bass and midrange up to about 800Hz-900Hz. I then want to switch to a ribbon to do the rest.

Now I know this is pushing both the woofer and the ribbon but I bet there are drivers out there which can do it!

The Raven R3.2MMX had been suggested to me but it is a bit expensive to experiment with if it doesn't work.

So another option I am considering is using two Fountek NeoPro 5i's in a vertical array per side.

I would like to know your opinion on whether this would help to extend their response low enough to 800Hz-900Hz without much compression and can still manage high SPL??

Also could anyone suggest a good line length and amount of stuffing for a transmission line (or as Thorsten calls it an acoustic labyrinth vented box) design for the Volt B2500.1?

Thanks a lot guys and gals! (not sure about the latter?)

[sreten]

Hi,


https://secure.wilmslow-audio.co.uk/...ssique_18.html

might be of some interest.

As would be digging out some info on the original DeccaVolt.

/sreten.

[inertial]

Hi Tenson,
IMO for 800Hz a good planar isodynamic is more "praticable".........
what do you think about B.G. Neo8PDR?
Cheers,
Inertial

[el`Ol]

Here is one from the professional sector, but I don`t know whether they sell drivers or just complete systems.
http://www.alconsaudio.com/site/technology/rbn401.html

[Tenson]

Originally posted by inertial
Hi Tenson,
IMO for 800Hz a good planar isodynamic is more "praticable".........
what do you think about B.G. Neo8PDR?
Cheers,
Inertial

I have been looking at this. I think with baffle loading and perhaps two or three in a small line array per side it could go down to 800Hz without too much compression or distortion. It would probably still need a little EQ if you look at the response charts though.

What is the sound quality of this driver like? My initial thought was to build something very high quality using the Raven R3.2MMX, but Thorsten also doesn't think this will go down to 800Hz-1KHz without noticeable negative effects.

I actually like the look of the Volt BM220.8 bass/midrange driver more than the B2500.1 having had a closer look. It goes much higher so gives more option on Xover but still has a low FS of 32Hz. The Radial PMC use in the MB2 has an FS of 29Hz so its not much different and they get 20Hz from it.

[ScottG]

at the extended low freq. extension you really only have large BG corp planar lines:

http://www.partsexpress.com/webpage....ctGroup_ID=577

though they are not true ribbons - inertial's suggestion is a good one (and you would have to spend a LOT more for something different but comparable)

the only comparable alternative to the Neo8s are the larger planars and heils from mundorf:

http://www.mundorf.com/english/index.htm

speaking of heils, you could also consider the original large heil (which I belive is selling at a rather modest cost direct from ESS/Heil or sometimes on ebay):

http://www.essspeakers.com/

another planar to consider is newform research:

http://www.newformresearch.com/us.htm

there are also the Hi-Vi's (planar):

http://www.partsexpress.com/pe/showd...number=297-413

finally - IF your a little more adventuresome:

Another DIY Ribbon thread

[ScottG]

Originally posted by Tenson



I have been looking at this. I think with baffle loading and perhaps two or three in a small line array per side it could go down to 800Hz without too much compression or distortion. It would probably still need a little EQ if you look at the response charts though.

What is the sound quality of this driver like? My initial thought was to build something very high quality using the Raven R3.2MMX, but Thorsten also doesn't think this will go down to 800Hz-1KHz without noticeable negative effects.

I actually like the look of the Volt BM220.8 bass/midrange driver more than the B2500.1 having had a closer look. It goes much higher so gives more option on Xover but still has a low FS of 32Hz. The Radial PMC use in the MB2 has an FS of 29Hz so its not much different and they get 20Hz from it.

http://www.diyaudio.com/forums/showt...3279#post63279

Sounds like what you really want is this though:

http://www.audio-consulting.ch/Hoogewoud.htm

I'd think you woiuld be FAR better off spending your cash on the Supravox 400/Exc/Ag (over the Volt) and then using the BG planars or something else less costly for the treble region. (..might see what Thorsten has to say about this idea.)

[Tenson]

Thanks ScottG!

Yes I was looking at the Neo8. It seems like two of them in a vertical array on a smallish closed baffle might Xover at 800Hz without much problem. A notch filter at 12KHz and a slight high cut to EQ out the rising HF. I'm not sure they will go high enough though. Some people report a response only up to 13KHz-15KHz?

Those Mundorf Magnetostatic drivers look ideal! It says on the PDF file about them that they are 'coming soon' Do you know if they are available yet? I have emailed them but not yet had any response.

Also, it shows distortion figures for the MagS 5 (the one I want) but I don't really know what is good, normal or bad. Any insight on this? 8% distortion actually sounds quite bad to me but I know speakers are a lot worse than we sometimes like to think!

The supervox looks like a nice driver and I am a fan of the field coil drivers but I don't really have room for such a large driver. I thought the B220.8 seemed good as Volt are known to make good drivers (they are British!) and it reaches low as well as quite high giving me a lot of room to play around with crossovers while still giving very extended bass. Being an 8" driver I suspect it has quite a fact punchy sound that would keep up better with a planar or ribbon?

I am going to see someone this weekend who has a PMC MB2/XBD set-up so I am hoping to take a look inside the PMC sub and see how they line their TL and the exact 'real' length of it. From there I will adapt it slightly to work with the B220.8 8" driver. At least I hope to! I'll post some pics of its internals if anyone is interested? There doesn't seem to be a lot of info on 'fake' transmission lines like PC and Medowlark use.

Also I am keen to build my own ribbon. Thorsten suggested making a 4" x 4" ribbon to reach low, but I don't see how to get the magnetic field to cover that distance equally. It seems like the edges would get pulled and the rest would follow, even if it was corrugated it would flex and distort over that large a surface area. Any suggestions?

I notice people place cross bars on the back of their ribbons to close the magnetic field, but why don’t they use a perforated plate to evenly spread the field right over the ribbon?

I downloaded Femm, but I have not got anywhere yet. I think a lot of it is going over my head.

Thanks everybody!

[el`Ol]

Originally posted by Tenson
The supervox looks like a nice driver and I am a fan of the field coil drivers but I don't really have room for such a large driver.

The FAL Flat C is small and has very good bass. Peter Daniel is using it with an Aurum Cantus ribbon and 2.7kHz crossover and he is very pleased.

[AnthonyPT]

Hi

For something that goes low without
strain maybe this will spawn some DIY
ideas. Francois claims it goes down
to 250hz and up to 20k in all its
wavebending dipole glory!

Regards

http://home.tele2.fr/mon-site-perso/index.htm