B&C DE250 comparison on XT1086

[D OB G]

ttan98,

Thanks for the advice.

David

[augerpro]

Originally posted by ttan98
I use the combo(DE50 and RCF)

Is the bolt pattern the same for the CD and horn? What is the RCF horn made of?

[ttan98]

Originally posted by augerpro


Is the bolt pattern the same for the CD and horn?
don't know most likely it is a horn


What is the RCF horn made of?

high density plastic, much heavier than the cheap Dayton or JBL plastic.

[hasselbaink]

I went ahead and ordered a pair of stereolab 1000Hz tractrix horns. These are milled from a stone compound. I will most likely use them with the B&C DE400 1" driver with neo magnet and mylar dome crossed somewhere between 2kHz and 3kHz.

I'm looking forward to hearing the combo. Wonder how much beaming is an issue with tractrix at 10 feet listening distance.

best
Kris

[Jmmlc]

Hello,

I confirm the excellent results that one can obtain using the B&C DE250 river mounted on the RCF H100 horn.


You'll find some additional
informations measurements and simulations about the B&C DE250 + HF100 horn on my friend Francis Brooke webstite at:

http://pagesperso-orange.fr/francis....I100_DE250.pdf

with a quite accurate method to optimize a crossover for a 2 ways enclosure comprising the DE250 and


Also you can find on the same website a comparison (frequency response, distortion curves H2 and H3, waterfall, impedance...) between several 1" compression drivers (including the B&C DE250) measured on the same horn (a Le Cléac'h horn J500 build by Marco Henry, with Fc = 500Hz)
http://pagesperso-orange.fr/francis....son_1pouce.pdf

Finally, you can see the results of a comparison (frequency response, distortion curves H3, spectrograms, pulse reponse, group delay curve ...) between several horns including the H100 mounted with the DE250 compression driver.


http://pagesperso-orange.fr/francis....co500_H320.pdf

Those documents are in French bust the graphs are easily understandable.

They are a good illustration of the "French touch" when it comes to audio optimization.

Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally posted by ttan98
Also I used horn from RCF, model: H100, this combo is very good, very under rated, I am using the combo now. Cheap and very good performance really believe me, I made measurements myself as well.Sounds good too, very dynamic.

[ttan98]

Thanks Jean-Michel.

[kstrain]

Today I had a chance to measure a BMS 4548 PLUS (sometimes sold as BMS 4548 OEM - label gives both names). I tried it on the XT1086 and RCF H100 horns; the first might be termed a gentle diffraction horn while the second has a bigger slope discontinuity on one axis. Measurements were made with the horns naked and then stuffed with quite a lot of wadding to ensure strong suppression of any "cavity modes" there may be (HOMs, perhaps, though I've neither measured nor modelled enough to be sure.).

Again I'm not going to include plots, as they only really make sense relative to each other and may mislead if taken as absolute. The first and main thing to say is that the BMS is much closer in smoothness of response to the DE250 than the ND1060 (and that is good).

The DE250 is probably still easiest to equalise, the minor differences with the BMS were: slightly less damped at the low frequency resonances (700Hz and just over 2kHz -but these are no problem), and two slightly sharper peaks at the top end of the band (above 15 kHz), whereas the B&C had one little peak before the sharp drop. I doubt I could hear the difference (with or without changing the EQ).

The BMS 4550 datasheet would give a reasonable guide as to what to expect from the 4548 PLUS - I guess they are not very different - perhaps the 4550 has tightened tolerances or different materials for a claimed 5% increase in gap flux at 2T(!).

Now why would I need a single BMS 4548?

Ken

[Horizons]

Does anyone have a design for the high pass (passive) xover for the DE250 in a WG?

[kstrain]

Originally posted by Horizons
Does anyone have a design for the high pass (passive) xover for the DE250 in a WG?

If you read a little French there is some info in the links in post 30 of this thread (if you mean WG to exclude horns that may not help).

Ken

edit typo - not sure if the info will be in post 50 but it is in post 30.

[gedlee]

Originally posted by Horizons
Does anyone have a design for the high pass (passive) xover for the DE250 in a WG?

The thing is that the crossover differs (or at least all of mine do) with the waveguide. Different waveguides have different loading and resonances and lead to different crossover designs. If you use one of my waveguides I can provide the crossover design for it, but it won't work on an arbitrary horn/waveguide.

[JoshK]

Hi Dr. Geddes,

I bought one of your 12" waveguides. I am using the B&C DE250. I wouldn't mind seeing the crossover if you don't mind sharing it with those who bought your WG. I am as interested in learning from the master as anything else.

Josh

[gedlee]

Josh

E-mail me and I'll get it to you. I don't want to post it as "public domain".

[Horizons]

Originally posted by gedlee

The thing is that the crossover differs (or at least all of mine do) with the waveguide. Different waveguides have different loading and resonances and lead to different crossover designs. If you use one of my waveguides I can provide the crossover design for it, but it won't work on an arbitrary horn/waveguide.

I understand completely. I am moving away from active and going passive so I am starting from scratch.

Are these prices for your waveguides per pair (I hope)?

http://www.gedlee.com/waveguides.htm

[a007udio]

How low can i use the B&C DE250 on XT-1086 ?

I would like to cross them with B&C 12PLB76. Any help?

http://www.bcspeakers.com/product.php?id=0000000044

[kstrain]

Originally posted by a007udio
How low can i use the B&C DE250 on XT-1086 ?

I would like to cross them with B&C 12PLB76. Any help?

\\

I was think to use allocator for the begining.

So there is no problem with the use of RME as a premaplifier like in DCX case?

I have EMC8000 microphone and TrueRTA and i can get Behringer DEQ.

PS: Thanks for link.

From the XO thread (which I also quoted), I see you seem to have measurement gear, etc. and likely the means to generate a crossover. In that case I'd say get measuring!

I think, though I couldn't prove it, that inserting some sound absorbing material in the horn helps (a la Geddes).

You'll need to equalise the DE250, of course, but that is pretty easy if you are driving it direct from an amp and know how to make good crossover functions in a PC.

I'd start around 1.4 kHz crossover, as the XT1086 is a bit small to go lower with directivity control. A bigger waveguide say 12" would be easier and better, if you can get one. I only tried the XT1086 due to lack of alternatives.

I've not used the 12PLB76, so have nothing to say about it.

Hope I interpreted your question correctly.

Ken

[gedlee]

Originally posted by Horizons


Are these prices for your waveguides per pair (I hope)?

http://www.gedlee.com/waveguides.htm

Sorry, no, thats each.

Originally posted by kstrain

A bigger waveguide say 12" would be easier and better, if you can get one. I only tried the XT1086 due to lack of alternatives.

Ken

Ken - I sell 12" waveguides and 15" ones per above. They are not as cheap as the injection molded XT1086, but they are much better devices.

[kstrain]

Originally posted by gedlee

Ken - I sell 12" waveguides and 15" ones per above. They are not as cheap as the injection molded XT1086, but they are much better devices.

Thanks Earl, I know you sell them, and am sure they are better, for at least 3 reasons, though how much better in each respect is hard to judge. I have been tempted to buy a pair of 12" waveguides since before you first offered the poly version for sale. I got the XT1086s before those were available.

Unfortunately the cost of your waveguides (to the UK) is currently prohibitive (though I do not rule out a future purchase).

Ken

[Wayne Parham]

There are differences between various horns, to be sure. But in general, a CD horn should provide the power response of the driver within the pattern. What you're really doing is to compensate the power response of the driver, which is flat to about 4kHz and then falls off at 6dB/octave.

Horns tend to modify response most at the low end, where they start having fairly well defined pipe modes and directivity gets weird. I would not use a horn that low. They also sometimes have differences at higher frequencies, usually as a result of some kind of discontinuity. This causes internal reflections which modify the impedance, response and directivity. But in general, as long as a horn is used at a high enough frequency and it is CD, it will deliver the power response of the driver throughout its coverage pattern.

The biggest differences are in compression drivers. Some have relatively high amplitude breakup modes at high frequency, and this causes them to sound shrill when used with a full 6dB/octave augmentation. They tend to sound better with a little less.

The crossover at the link below works very well with drivers that have reasonably behaved breakup. I use it with the DE250. It provides flat response up to 4kHz and 6dB/octave augmentation above that.

• Pi Crossover schematic
• R1/R2/C1 values for matching various sensitivity levels
• A few useful documents: Crossover Electronics 101, etc.