811b/806a 16ohm with jbl 2226 or supravox 285 GMF

[ark]

to replace my recently hacksawed Ohm's...
(kidding, haven't done it yet)

I have a pair of Altec 811b with 806a 16 ohm drivers.

To mate with em I've narrowed down my options to two drivers and I cannot for the life of me decide which to go with.

the JBL 2226J
https://www.performanceaudio.com/med...0/007466_s.pdf

or

the supravox 285 GMF
http://www.supravox.fr/haut_parleurs/285_GMF.htm

no more alternatives. thanks though. its gonna be one of these.

But which?

I like the supravox for its efficiency, size and what i think is a lighter more dynamic cone? which i could pair with other speaker combos in the future if i tire of the 811s.. also, its a good candidate for OB if and went I want to do that..

the jbls are highly reccomended by users with the 811b 806a combo.. but with all of that high wattage support, something must be lost in musicality or detial right? for low wattage input?

I only plan to run 10 watts max thru them..

the cabinet design will follow once i decide and order these..
this week.

[Pano]

Thanks for the post, ARK.
I too, have a pair of 16 ohm 811/806A and have been looking for a bottom end driver.

These are 2 drivers that I have not looked at, so thanks for the idea.

The Supravox has a much lower moving mass than the JBL - 20g vs. 98g. But the Supravox is a 12" driver, so it makes sense. Or to look at it another way, the JBL has about 2.5X more mass per sq. cm of surface area.
Don't know what that does to the sound, but it makes you think.

For me, a 15" is likely out of the question because of space limitations. But maybe...

I'd love to know what you come up with.

[ark]

thanks.. i didn't look at the moving mass figures, that certainly reflects what I had "felt" the difference would be between the two..

though im still in a toss up over the two..

the jbls distortion curves, freq. resp. curves etc are very very nice.
plus they go to 30hz!

this is a tough one eh!

wait and see... i guess. = )

[GM]

Greets!

You choose components based on the app, with the XO point(s)/slope(s) typically being the primary criteria in a HIFI one. The JBL's high current capability has no bearing per se since it's going to be power limited, leaving only efficiency and inductance as secondary considerations. Since both have virtually the same eff. in the XO's passband, the JBL's higher Mms is a non-issue and it's higher inductance can be annulled if you don't mind the extra components.

A rule-of-thumb (ROT) is that you want a ~flat response for at least an octave on either side of a 2nd order XO, so the 'slower' the slope, the wider the woofer's ~flat BW must be and vice-versa. Then there's the issue of ~matching polar responses in the XO's BW as well as the distance between the driver's acoustic centers relative to the distance to the listener. Assuming an XO point/slope that gets the most out of the 811, the JBL or similar is better overall while the Supravox or similar would be the 'no-brainer' choice for either a relatively high XO point (> ~1200 Hz)and/or 'slow' slope.

GM

[Pano]

Hi GM, good to see you here.

Assuming an XO point/slope that gets the most out of the 811, the JBL or similar is better overall while the Supravox or similar would be the 'no-brainer' choice...

Can you expand on that a little? From the FR plots we can see that the Supravox goes up pretty high. Easy to cross. But what is it about the JBL that you like?

the JBL's higher Mms is a non-issue

Why? Doesn't a bigger mass mean more inertia? Sir Issac's 1st law and all that?
Of course, being of a much larger surface area, perhaps the JBL does not have to move as far as the smaller Supravox, so inertia is lower.

What is your thinking on this?

And perhaps we need to establish a XO point for the 811/806a.

[ark]

Thanks GM,
You mentioned one of the other reasons for considering the supravox, using a higher xover point on the 811s which im told will help eliminate
honk ... 1200-1600hz - the sup would pretty versitile for this an other speaker experiments. hmmm..
darn,

neil young. after the goldrush. the first time ive listened to this.. brilliant. i mean really brilliant!

[GM]

Originally posted by panomaniac
Hi GM, good to see you here.



Can you expand on that a little? From the FR plots we can see that the Supravox goes up pretty high. Easy to cross. But what is it about the JBL that you like?



Why? Doesn't a bigger mass mean more inertia? Sir Issac's 1st law and all that?
Of course, being of a much larger surface area, perhaps the JBL does not have to move as far as the smaller Supravox, so inertia is lower.

What is your thinking on this?

And perhaps we need to establish a XO point for the 811/806a.

Greets!

Thanks! Been really busy of late and probably will be for some time to come, so not much time to follow the forums.

What's not to like besides this model's VC coil's relatively high inductance? While I prefer the old Altecs, I've used the 8 ohm version of this driver (2226H) in both horns and MLTLs with excellent results.

High Mms only spells 'trouble' when the motor's not strong enough to get it going or the driver doesn't have enough HF BW to track the signal through the XO BW, a problem the JBL definitely doesn't have if the chosen XO point/slope is within the driver's limitations; and as you noted, its greater acoustic efficiency means it doesn't need as much HF BW to accelerate it.

GM

[GM]

Greets!

You're welcome! Well, you can eliminate the 511's & 811's 'honk' without resorting to high passing it, but it requires some tweaking along with CD horn compensation.

GM

[ark]

Thanks GM.

so... if I get the 2226j s 16 ohms

to go with the 800hz 16ohm altec 806's and 811 horns.

Roughly what xover design would you suggest to start with?

I was planning on a simple first order with a 12uf cap on the horn
and 1.3? mh inductor on the 2226... with resistors to pad the horn output down.. or an short term lpad.

sound about right?

aside from the jbl specfied bass reflex enclosure for this driver, any other alternative enclosures you think might work well? jensen cab? la scala? karlson?

mltl? you said you had good results with one. tuned to what freq?

with a mltl i might expect to stay pretty flat down to 30hz ?

thanks!

this is great.. im curious to see what panomaniac does too..

[GM]

Greets!

You're welcome!

Back when I used these it was common to just use the stock Altec XO, which was a textbook 2nd order Butterworth. These were originally voiced with matching impedance amps, so for tube p-p without tone controls or SS amps I typically used a matching impedance series resistance (either non-inductive power resistor, or better still, the right size magnet wire) with a HF bypass cap (PIO preferred) paralleled around the shelving pot to 'lift up' the extreme HF (CD EQ). Since this value is very room/person dependent, try cheap 0.1 and 1.0 uF to get a baseline.

With 1st order and 10 W available, at least a 16oo Hz XO point is required to protect the 806 if a loading cap isn't used. Also, if the JBL is used, then I imagine it will need reactance annulling impedance compensation for best results, which will affect the inductor's value. Unfortunately, this is too high an XO point to get the best off axis response, which may, may not be an issue depending on the room/system layout.

Anyway, check with the guys over on the pi speaker forum to see what XO design they're using with this driver combo: http://audioroundtable.com/PiSpeakers/

WRT cabs, this is dependent on a number of factors, such as room size/shape, speaker positioning, output impedance of the amp, etc.. For sure, to get to 30 Hz with any authority will require a fairly large cab with either a horn or corner loading and/or enough series resistance to balance the FR out, though of course efficiency will suffer. Since I used them during the era of LF BW limited vinyl and early CDs, I never tried tuning them much below Fs. Indeed, my 'standard' cab was based on a Vb = Vas, Fb = Fs alignment and in a 'tower' layout (aka MLTL), it wound up being naturally mass loaded to ~36 Hz, then fine tuned them in-room via vent damping and/or series resistance.

GM