Which driver for 300Hz front loaded wood horn?

**theophile** · February 24th, 2011, 06:39 AM

atilsley,
I'm looking at the Azura AH 425 for mating with a pair of Altec 288-8Ks.There is a graph on the Azura website showing decent response down to 400Hz.

http://www.azurahorn.com/JA6681B%20o...%20%282%29.pdf

Just offering this as another factor for consideration.

**atilsley** · February 24th, 2011, 06:57 PM

Thanks theophile

How high would you run the 288's in that horn?

**theophile** · February 24th, 2011, 07:10 PM

Around 5Khz or so.Then cross to a smaller compression driver like the GPA 902(which I also have).Please remember that I am relatively a bumbling novice(with an active crossover,is there anything more dangerous?

).If I have given you poor advice,I would hope that the informed on the board will kick my arse.

That's what I like about the US censorship software programs;When you spell arse it doesn't delete it.Arse.Arse Arse.

Immature ain't I? :nosepicker:

**atilsley** · February 24th, 2011, 08:11 PM

Theophile, thanks.

You've helped me firm up in my mind that the two-inch format is the way to go for the 500-5,000 range, then use something else for HF.

That being the case, would the 902 act as a very good mid-high frequency driver vs, say, a dedicated tweeter horn, eg Beyma cp25 (2.5k-20,000Hz), or JBL copy Beyma CP21 (3.5k - 20,000hz)

I'd love to go with the Altec 390 (500hz-5,000), then the 902 (5,000-18,000 say).

Andrew

**SOOTSHE** · February 24th, 2011, 08:33 PM

Originally Posted by atilsley

Theophile, thanks.

You've helped me firm up in my mind that the two-inch format is the way to go for the 500-5,000 range, then use something else for HF.

That being the case, would the 902 act as a very good mid-high frequency driver vs, say, a dedicated tweeter horn, eg Beyma cp25 (2.5k-20,000Hz), or JBL copy Beyma CP21 (3.5k - 20,000hz)

I'd love to go with the Altec 390 (500hz-5,000), then the 902 (5,000-18,000 say).

Andrew

I think the 902 would be a great dedicated HF driver, but I think you'd need to use something like an 811 to achieve a better sound than with , say, a 2404 or a slot.
In other words, I think if you used the 902 on a very small horn you'd not be getting the full benefit of the 902 driver & would be better off using the JBL's.

From experience, I wouldn't use the Beyma copy of the JBL slot. I tried one & thought it was just terrible.
I've had great results with the 2404 & thought it was better than the JBL slot. Asmoother top end with less sizzle, but still great extension & airiness.

**atilsley** · February 24th, 2011, 08:59 PM

J, thanks.

To qualify -

I'm 'only' wanting to use new components...as I'm keen to try and develop a commercial product...hence the continual reference to GPA.

Can you kindly comment on the idea of the 390 GPA driver for 500-7000 range, then the 902 operating above...? (I note your comment already re the 902....but what about when paired with a 2-inch driver for the lower range....aka Avantgarde).

Andrew

GM · February 24th, 2011, 10:31 PM

It's a decent super tweeter by today's standards when terminated with a matching conic profile, but as I previously noted, its diaphragm and throat are way too large for a high SQ ~5-20 kHz BW. For this we need a ~3/16" dia. throat and proportionately sized diaphragm/VC. Since the ST horn will only need to be around 2.7" including the driver's stub, significant delay will be required.

GM

**theophile** · February 24th, 2011, 10:55 PM

I should say here that I also see the need for another driver to take-over from the 902 at about 12khz.

Ribbon?I'd love to hear the Pioneer beryllium ribbon supertweeter.

I'm slowly assembling the drivers and horns.No hurry.Nothing to prove(Some wank to be found in my posts.No data however

).

**SOOTSHE** · February 26th, 2011, 12:01 AM

Originally Posted by atilsley

J, thanks.

To qualify -

I'm 'only' wanting to use new components...as I'm keen to try and develop a commercial product...hence the continual reference to GPA.

Can you kindly comment on the idea of the 390 GPA driver for 500-7000 range, then the 902 operating above...? (I note your comment already re the 902....but what about when paired with a 2-inch driver for the lower range....aka Avantgarde).

Andrew

Andrew,
I think the 902 paired with the 390 would be a good combo, but I think your choices of horn for the 902 will be the limiting factor here. It would be much simpler to use the Beyma "baby cheeks" tweeter and very little, if any, loss of performance. Easier to build into the cabinets & much better aesthetically. I recommend the Beyma driver only because you want to use new components.....personally I would go with the JBL 2404....much better quality of sound.

**Ronald Lee** · February 26th, 2011, 03:44 AM

Originally Posted by atilsley

Theophile, thanks.

You've helped me firm up in my mind that the two-inch format is the way to go for the 500-5,000 range, then use something else for HF.

That being the case, would the 902 act as a very good mid-high frequency driver vs, say, a dedicated tweeter horn, eg Beyma cp25 (2.5k-20,000Hz), or JBL copy Beyma CP21 (3.5k - 20,000hz)

I'd love to go with the Altec 390 (500hz-5,000), then the 902 (5,000-18,000 say).

Andrew

I believe JBL recommends min xover 7KHz for their 077/2404 slot tweeter. The JBL 075/2402(sonically obosolete - IMO) min xover is 3.5KHz.

Personally, I would go with 500-7KHZ with GPA 390, and a JBL 077/2404 >7KHz, instead of a GPA 902 and Altec 811 horn.