[dewar]

Hi,

 I'm about to get a DEQ2496 to go with OB B200's. I know of the dangers of boosting the bottom end but was wondering how feasible it is to flatten the B200's response to say 15k?

thanks

bevan

[Dmason]

Active contouring is at its best when subtractive in nature. Avoid the inclination to be additive, it robs the amplifier of power, particularly below 250Hz, which requires something like 70% of an amplifier's power. The B200 is a whole other animal when using DEQ, and therefore avoiding passive filters, which negate the sort of 'by default' active amplification of using this type of driver, by virtue of the fact that one driver is being powered by one amp channel.

You can effectively raise the top end using very little amplifier power, and the B200 readily responds. Good luck with the Behringer. It is a well thought out machine, and represents great value. I believe active EQ is pretty much mandatory with open baffle speakers.

[dewar]

thanks Dan.

I take it then that there is no danger headroom or otherwise to bump up the top end. Even if its to 20k? That would be a ±20db boost, but as I dont listen over listen over 80db it would be like playing the original signal at 100db which should be o.k with a Signature 30 (provided the bottom end isn't being boosted anything like this).

I'm using a bsc now but would take that out of course.

Thanks again

Bevan

[JLM]

Dan makes a good point I hadn't considered, to keep the straight wire view the amp has of the single driver as unobstructed as possible for the best synergy. 

Someday I'd like to add the DEQ2496 (or just software if I can manage a PC based system) just to replace the BSC/zobel circuit I currently use with something in the digital realm, but need to go back to separate transport/DAC first.

I can't imagine a problem adding 20 dB to the top end at your listening levels and the B200's power handling specifications.

[Dmason]

Actually, I know you will have a good result because I have used extensively the combination of Signature 30 with B200, and I stated early on that T amps + B200 are a match made in heaven. The B200 really shines when using abit of juice into it; the best DEQ result can be had by using the SPDIF and this way the signal is tweaked only in the digital domain. Then later on you can consider using the high pass and run the B200 >200hz, relieving it of ALL lower register duty, for which the speaker will immediately thank you, and add active bass amplification, the newer BASH amps are very promising, and any of the bass drivers we have learned work well, the Hawthorne 15, and Eminence Delta 15LF, being among the cost effective choices. I have learned that a Ripol-loaded dual 15 inch per channel setting, behind the main baffle works very well. It also allows you to get away with a far narrower baffle of ~16-18"...

This M.O. was the basis of the DarkStar thang, which worked best as a bundled system, and is a truly great sounding speaker solution, if I may say so.

[JohninCR]

When I add a shelving boost EQ to the top end of my B200s, I hear very little difference, vs adding a tweeter which makes a clearly audible difference.  That's even when I apply +15-20db of EQ.  There must be something else happening related to phase as the EQ is applied making it not achieve the desired result.

[dewar]

Dan, I've got a sealed 'Critical Q' sub using Peerless 12" and two Peerless 10" on the way which I'll put each in an H-frame OB, but I have been wondering if there is anyway I can highpass the B200's. I'd do EQ in the digital domain and feed that to my Monica2 which then feeds the Sig 30, but both subs and B200's are getting their signal from the Sig 30 so I cant filter one and not the other if you know what I mean. Does the DEQ have both fullrange(digital) and filtered digital outputs? The DEQ would then have to be used as a volume control no?

JohninCR thanks for answering my question. It raises more though:)
I was thinking of getting  B&G Neo3 tweeters from Danny at GR Research. Originally the plan was to use them high passed at 10k and mounted on the back of the baffle, for added 'air' mainly, which apparently would not effect their measured FR. Danny said that to mount them on the front in an attempt to get measurable lift in the last octave would not be a good idea as it would cause large phase related dips in the FR. But now that I've got a DEQ the way, could this not be used to flatten the effects of that comb filtering?

I really value any advice and direction, I wouldnt be here without you guys.

Bevan

[Dmason]

The DEQ has full range SPDIF-out. I have only used it for mains in DarkStars. The Behringer DCX has a "Sub Out" as I recall. I recommend researching that one as well... I have a Rane RPM which has two sets of assignable outputs in two channel. Bi-amping otherwise would become the necessary way to go, which can as I suggested, be done pretty cost effectively. the Rane RPM line of DSP is pretty serious pro audio, and not all that cheap.

The sound of Monica2, Signature 30, and B200 I know well. Nice.

[JohninCR]

Bevan,

Unfortunately I don't have an answer for you.  The system I use has XO, EQ, and phase correction of XO's, so I know it would be a snap for me to integrate.  It's my understanding that EQ creates phase shift too, but I don't know how to predict it.  IOW maybe, or it could make the problem worse.  I generally use EQ to broadly boost bass to offset cancellation, so the effect on phase is very gradual.  I do use a narrow notch to correct a dip around 1khz with FE108's to good effect.  On the other hand when I tried to EQ out the high Q cone resonances of the FE206, I succeeded in flattening response, but the sound seemed over-processed.

Give it a try.  The DEQ may give you the ability to effectively implement a 1st order XO between the tweeter and B200, giving you the "air" you want without stressing either driver as long as you do it up high like you mentioned.  Thankfully OB test baffles are so easy to build that you can test a lot of different combinations to see what you like best, and have fun doing it.  My vote would be to make a front firing tweet work, but my music tastes may be different.

[konut]

The main problem with what you want to do is using only one amp to drive both the B200s and the sub. If there was any way you could find to drive the subs with a separate amp it would solve most of the difficulty involved. Adding the NEO3, facing backward, with a simple capacitor, of the correct value, shouldn't be a problem to get the 'air' you want, even with equalization. The DCX would work as its got multiple outs, but it requires some mods to make it work in a home setup(the output is way too hot and needs attenuation to get it to work happily with the Sig 30) but you really need another amp for the subs. That would also make the B200-Sig 30 combo more dynamic and cleaner.

[dewar]

Thanks Konut.

Should have said, my present sub has its own plate amp, and the two dipole subs will share another plate amp, of of the Partsexpress 350 watters. (either in series or parallel I havent decided yet).I'll run the subs from the Signature 30's pre outs.

So it seems no way to limit the bass going to the B200's without also depriving the subs. But I think I'll attenuate the bottom 2 octaves by say 12db on the DEQ and then put in the reverse filter on the BFD which will bring the subs back to normal. Might help the B200's out a bit.

I know less than it might seem about electronics so I'd better stay away from the DCX.

For the tweeter I thought of splitting the Sig 30's pre-outs(can this be done ad infinitum without degrading signal?) and running them to a T-amp. This way I can control the gain of the tweeter. Good idea you reckon?

John, the phase shift caused by EQ, what deleterious effect does this have?(other than to effect the FR, but then we're flattening that arent we?)

Sorry for all the questions. The music I hear now is just wonderful but I cant help feel that true perfection is almost within my grasp now. 
who am I kidding 

[konut]

The phase cancellation that Dannie Ritchie talked about in another thread was when he added them to the front baffle of one of his existing speakers. Since the extreme HF content is so attenuated on the B200 there should be little cancellation especially since the NEO3 would be facing rearward. You can't cancel whats not there.

[dewar]

Quick off topic question that I'm hoping you guys can help with,

I've just noticed the Behringer DEQ has square S/PDIF and XLR AES/EBU connections, but no coaxial digital out like I'm using at the moment between DVD player and DAC. Is there any way to make them play together?

cheers

Bevan