B&C Compression Driver and Horns

[gedlee]

Tractrix horns aren't CD.

A point often forgotten in these threads.

 

[Yaho]

Where can I buy those cheap chinese drivers?

Hi Earl


Thanks

Drivers are a commodity, I can make a good system out of any of them - as long as they meet some minimum standards. I have done systems with drivers over a range of about 10:1 in price and found that none of them made much difference. I evaluated a compression driver from China that was a virtual copy of the DE250, worked pretty well - it was $15

Since the drivers are not the most important factor, I would love to try those cheap drivers. Where can I find them?

Thanks

 

[gedlee]

From a company in Guahzhou called Boke Audio. I think that you would have to buy a lot of them though as they don't distribute outside of China.

 

[Yaho]

Thanks

Thanks Earl

Guangzhou is a place where many OEM stuffs are manufactured at. It makes sense.

To my eyes, they look just like Pyle drivers.

Your wave guides look pretty.

 

[gedlee]

Thanks, I've tested them they work pretty good, but build was inconsistant.

 

[col]

Iv'e recently completed the speaker project Iv'e been reporting on here, using the B&C DE10-8 Mylar compression driver, Dayton HR10RW "waveguide", Selenium ADM25-25 adapter, Gedlee foam plug and Eminence Beta 10a.

Just putting up a photo:

http://pix.minirig.org.au/main.php?g2_itemId=762

col.

 

[JoshK]

Col,

How did you xo the speakers?

 

[CLS]

Hi,

I'm also very interested in details of that WG + adaptor. Is it possible to see the throat now?

Thanks a lot,
CLS

 

[col]

I'm using a active ESP P09b and crossing over at 2.2khz, all my equalization is done via a Behringer DEQ2496 (only using digital in/out). I don't think the DE10 will go much lower than 2.2k. The amp is a 4 channel 41hz amp9-basic.

To see the waveguide throat look at the previous photos.

http://pix.minirig.org.au/main.php?g2_itemId=588&g2_page=1

 

[CLS]

Ah! I remember these pictures. Thanks.

So, I see that "step" from adaptor to WG's throat. It looks not being smoothed by any means and left as is.

By this contour step and the short cylindrical section of adaptor, is there any audible inferior effects?

 

[col]

I smoothed out the step using some clay/putty and by sanding it down. The active EQ of the DEQ2496 dealt with the rest.

 

[pos]

very nice!!
2.2khz is quite high, at that frequency the 10" woofer must be very directive. But it makes sense: the Dayton waveguide is 75°, compared to 90° for Gedlee's waveguides. Still, maybe 1.5khz would be a better match?...
Do you have a mesurement mic ?

Where did you find/cut the foam?

 

[gedlee]

He bought the foam plug from me. Col - I think that the foam looks better if you sand a spherical surface in it.

And as to the throat correction you said "The active EQ of the DEQ2496 dealt with the rest." - EQ cannot correct the problems created by a poor throat as these are time, frequency and spatially dependent issues which no EQ can correct.

 

[col]

I don't think the Dayton "waveguide" is very correct. I'm surprised how different they sounded when I put the foam plug in and re-EQ'd. Also, I built the backs up with car filler to stop them ringing.

I don't mind the foam plugs sticking out a little bit, sanding seemed to be a bit awkward and I didn't want to damage them. I think if I tried to remove them now the glue would rip big chunks out of them.

I'm quite happy with how the speakers sound and they have worked out to cost around AU$750 for the pair, which I think is very reasonable for what Iv'e got.

They play very loud and clear. The best thing I like about them is that you don't have to be sitting directly in front of them for the sweet spot. I can pretty much be anywhere in my listening room and it all sounds sweet

Would be good to do some measurements, with something other than the DEQ2496. Anyone have any suggestions software wise? I have a ECM8000 and a phantom powered pre-amp/mixer I can use. Plus, I have either a Linux or a XP computer I can hook up via a USB soundcard.

col.

 

[gedlee]

I don't think the Dayton "waveguide" is very correct. I'm surprised how different they sounded when I put the foam plug in and re-EQ'd.

People keep talking the waveguide contours as if the shapes are something magical. To me at least 1/2 of the improvment in the more modern approach to waveguides IS the foam plug. Many people are using horn/waveguides now, but very few are using foam and I just find that without the foam "your not quite there".

 

[col]

I read in another thread somewhere that if the waveguides are not correct the effect that the foam plugs has is even more pronounced than with a correct waveguide. I have no evidence to back that up but I think in my case with the Daytons it may be right.

 

[CLS]

Does that mean the foam make a significant change to your Dayton WG?

 

[col]

yes, I think so. I have no idea how you would measure the improvement though, especially seeing you have to re-EQ after fitting them.

 

[gedlee]

I read in another thread somewhere that if the waveguides are not correct the effect that the foam plugs has is even more pronounced than with a correct waveguide. I have no evidence to back that up but I think in my case with the Daytons it may be right.

I'm just guessing at how the foam will affect "other" waveguides, its likely different in every case. My point is that its a profound effect on any good waveguide. Most people seem to be missing this fact.

Last night I went to a freinds house who has an old set of JBL SR8's. I found the horn intolerably harsh and suggest that maybe some foam might help. We cut a piece and stuffed it down the horn. Better! We put a block of it on the outside where the acoustic lens was. Better yet! But there was still some residual harshness that I did not like. So, yes, foam always seems to help, but can it fix a disaster - sorry no.

 

[pos]

yes, I think so. I have no idea how you would measure the improvement though, especially seeing you have to re-EQ after fitting them.

How much eq did you had to add (at each frequency, if you have th data)?
How does this setup compare to your previous one (the one with the cheap JBL PT waveguide) ?

I am thinking about trying to add some of this foam in the diffraction slot (the part where the wall are parallel) of my H9800 clones (the horns of the JBL K2 S9800).

Here is its profile, side view :

Earl, do you think it would be beneficial? Is the diffraction slot the better place for this plug? I am a little afraid of adding too much foram, because I already need more than 20dB compensation to get flat to 15khz without any foam. This horn is basically an improved version the one in the 4430.