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A stupid question...

78.29.224.52
Posted on June 2, 2017 at 18:03:13
KanedaK
Audiophile

Posts: 2519
Location: Brussels
Joined: April 27, 2010
 I wanna equalize the bass (40hz - 400hz) section of my bi amped system.
I wanna put the equalizer between the active cover and the bass amplifier.
Is there any problem resulting from the fact that the signal for the bass goes trough some added circuitry vs the signal to the high pass? Like, could there be some unwanted delay trough the equalizer?...

 

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RE: A stupid question..., posted on June 3, 2017 at 05:39:04
Scott L
Audiophile

Posts: 353
Location: Knoxville
Joined: February 2, 2001
 I have been doing exactly what you propose to do, for several years now. The results with EQ are a dramatic improvement in sound quality.

 

Analog ?, posted on June 3, 2017 at 13:23:25
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 Analog or digital EQ?

I used to do just that with an analog EQ that sounded a bit noisy and opaque in full-range use.

Digital will have some latency issues (delay) to deal with.

 

RE: A stupid question..., posted on June 3, 2017 at 15:09:06
Coytee
Audiophile

Posts: 95
Location: Knoxville, TN
Joined: May 19, 2010
 I don't get it...(but then, I'm not the sharpest knife in the drawer)...

If you have an active crossover, why don't you just put your EQ changes in there?

 

RE: A stupid question..., posted on June 3, 2017 at 15:24:43
merdy
Audiophile

Posts: 1626
Location: New paltz,ny
Joined: July 25, 2001
 Yes yo can do it although you might have to adjust gain and also the signal might invert phase ,then you're adding another component that might have crappy op amps etc,this all shows up with hi eff speakers ,
In the past I used a audio control Richter scale which had a crossover and bass eq ,it was fantastic with some of my bass horns to tame room nodes ,using all digital is workable crossover solutions with some eq although I don't like it on vintage drivers.
But you have really not explained as to what you are planning to do or why.?
Hope this helps
Silence is golden duct tape is silver

 

Not a stupid question., posted on June 3, 2017 at 20:34:58
Inmate51
 Asking questions is a fundamental way to learn. :)

Filters do add delay to a signal. In your case, it's extremely small, and, for practical purposes, irrelevant.

What you are doing is accepting a tiny imperceptible flaw in order to resolve an obvious glaring flaw. I'd take that deal.

Just be aware: If the problem is, in fact, a speaker issue, you're on a good track. But, if the problem is actually a room acoustics issue, EQ will not fix it - EQ can only make it less noticeable, at the expense of the quality of the speaker output. If it's a room acoustics problem, you have to fix the room.

:)

 

RE: Analog ?, posted on June 4, 2017 at 09:48:09
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 DJK is correct about latency issues of digital crossovers. However it happens to both the bass and treble sections equally, so the net effect is inconsequential.

If the operating frequency is 96 Khz vs. only 48 Khz., then the latency will be half as much with the 96 Khz. filter.

 

RE: A stupid question..., posted on June 4, 2017 at 11:18:42
Scott L
Audiophile

Posts: 353
Location: Knoxville
Joined: February 2, 2001
I may have incorrectly assumed it was an analogue based crossover. I guess i still don't think in terms of digital. I declare, I have now lived long enough to consider myself old-fashioned. drats !

p.s. placing the e.q. unit in the low pass leg, keeps any artifacts out of the upper range, where to me, they are much more noticeable.

 

RE: Analog ?, posted on June 4, 2017 at 14:35:37
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 Matters nothing what latency the crossover has, he is talking about adding an EQ into the low-pass output, and if it's digital it will have its own latency issue.

 

RE: Analog ?, posted on June 5, 2017 at 01:53:40
KanedaK
Audiophile

Posts: 2519
Location: Brussels
Joined: April 27, 2010
 I'm using an analog active crossover on the low pass only.
The high pass is fed from the full range signal straight from the preamp to the power amp: I've created a first order high pass filter inside the power amp by changing the value of the input capacitors. The -3dB corner frequency is 100Hz. It's only purpose is to avoid amplifying unnecessary low frequencies. The power amp feeds the mid-high section of my preamp trough the original 3 way crossover. Passive high-pass at speaker level is 400Hz. Therés a 6 ohms resistor connected to the woofer outputs on the 3 way crossover.
The preamps second output goes trough an analog crossover and feeds the bass amplifier driving the bass horns.
That's where i wanna insert an analog equalizer.
Reason I use this "half passive / half active" bi-amp setup is that I really can't stand the sound of my active crossover in the midrange and high frequencies. Doing like I do gives me maximum transparency and with the low bass filtered from the mid-high amp I don't have any headroom problem.

Problem I'm trying to fix is a peak centered around 125Hz (150?) that's due to the bass horns and most likely worsened by the room acoustics.

That Audio Control Richter scale looks like a great product: I could have crossover and equalizer in the same box, would be ideal!

 

RE: Analog ?, posted on June 5, 2017 at 08:08:41
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 Assuming the delay/distance/latence/whatever is withing 1/4 wave, I don't see much of an issue, do you?

 

RE: Analog ?, posted on June 5, 2017 at 08:22:52
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 The problem you are trying to fix is inherent in the FH-1 and LaScala SHORT HORN bins. It's at about 140 Hz. with a 7 db peak.

You can get a 2 channel mini DSP at a little over $100 to take care of that problem, which we all have had.

I'm assuming you are using a subwoofer below 100 Hz. Which is the best way to go, especially if it's a horn.

How I got rid of that 140 Hz. peak, is I designed a Quarter Pie bass horn and uploaded it on the Klipsch forum to help others do the same. But I still ended up with subs below 50 Hz. (twin Danley DTS-10's)

You get an extra octave of bass for free (flat to 50 Hz. with K-33)and a much flatter response and it only sticks out an extra foot from the corner.

 

RE: Analog ?, posted on June 5, 2017 at 13:10:27
Head_Unit
Audiophile

Posts: 269
Location: Los Angeles
Joined: February 5, 2004
 Huh? And what speakers are these?
"The power amp feeds the mid-high section of my preamp trough the original 3 way crossover..."
I think this is a typo? I presumed your preamp was feeding two power amps:
- 1st with active lowpass (what frequency/slope/etc?) feeding the woofer horn.
- 2nd running quasi-fullrange (actually with 1st order highpass @ 100 Hz) feeding the original speaker passive crossover which then highpasses the mid at 400 Hz and whatever for the tweeter.
Or did you actually pull out the crossover and put it in series with the...preamp??

As for "Therés a 6 ohms resistor connected to the woofer outputs on the 3 way crossover"
- Is that to not have the crossover leg "open"?
That resistor is just wasting power and reducing headroom, if you could specify/sketch the crossover we could help you disconnect the woofer lowpass section entirely.

As a loudspeaker design engineer, yes, I agree sometimes it can be hard or not really possible to replicate a passive crossover actively, whether via analog or digital.

Howver, I wonder what your 400 Hz highpass network looks like-and if you couldn't simply change your capacitor to 400 Hz and adjust the lowpass for blending. If the mid really needs 12 dB/octave, you could additionally put a capacitor across the input and get a shallow 12 dB (unless the internal capacitor is essentially at the input, unbuffered)

 

RE: Analog ?, posted on June 6, 2017 at 01:02:29
KanedaK
Audiophile

Posts: 2519
Location: Brussels
Joined: April 27, 2010
 Yup of course it's a typo. I'm writing from my phone, sometimes while I'm in the public transports :) sorry about that. Of course I meant that my preamp has two outputs, one that feeds the mid/high amp full range, the second feeds the bass amp trough an active crossover.
I appreciate your concern, however I believe I have found a very decent compromise here. The only thing I might wanna do is play with a steeper crossover on the low pass, to hear the difference, but driver integration isn't really an issue so far (probably due to the lowish 400Hz xover frequency.
At some point I might wanna try the HD version of the miniDSP but somehow going digital freaks me out.
I chose a 100hz corner frequency on the high pass (capacitor) to not mess with the passive crossover slope + natural horn/driver roll-off.
I put the 6ohm resistor on the woofer crossover leg as recommended by the designer of the network I'm using (ALK engineering "universal", original version)
Apparently doing so allows the crossover to keep presenting a flat 8ohm load to the amplifier. I'm no crossover specialist so cannot comment on that, however those were expensive networks and I don't wanna take them apart or mess with them.
If there is a loss of headroom I really can't hear it (especially since I filtered the <<100Hz frequencies out). I would have the police at my door before my 8watts driving the mids-high starts clipping!
Now I understand, it's all compromise and a work in progress. But it sounds great. Just have a 150Hz bump that is due to the bass horns used (peavey FH1) and that I would like to tame down - subject of this post.
One day I will go for fully active - "the right way" when funds allow me to get something that sounds as good as my preamp does. Anything that makes the sound grainy, hazy, grey - like a lot of cheaper opamp based designs- is a big no-no to my ears. :)

 

Well said~nT, posted on June 6, 2017 at 01:13:52
Cleantimestream
Audiophile

Posts: 7551
Location: Kentucky
Joined: June 30, 2005
 ~!
The Mind has No Firewall~ U.S. Army War College.

 

Thanks!, posted on June 6, 2017 at 07:24:19
Inmate51
 I've been studying and working this stuff for a long time, and am starting to figure it out. ;)

 

One More Thought, posted on June 6, 2017 at 07:38:35
Inmate51
 Having the crossover at 400 Hz isn't the best place to put it. That's right in the middle of many musical instruments' fundamental range (tenor sax, clarinet, trumpet, viola, etc.) I know, I know - who cares about the viola? ;)

If it works for your speakers capability-wise, I'd recommend moving it down at least an octave to maybe 150-200 Hz, preferably to more like 125-150 Hz.

Of course, driver directivity comes into play here as well, so there's that to consider.

:)

 

RE: Analog ?, posted on June 6, 2017 at 09:20:35
Don Reid
Audiophile

Posts: 890
Location: Rural NW Georgia
Joined: February 2, 2001
Contributor
  Since: April 1, 2010
 KanedaK wrote: "At some point I might wanna try the HD version of the miniDSP but somehow going digital freaks me out. "

I went digital with a DSP from DEQX. I have never regretted it. Some folks such as Jonathan Valin of the Absolute Sound claim to hear distortions introduced by digital circuits. I don't. My speaker rig is an all horn loaded triamplified system capable of very high resolution. Everything digital DSP does right far outweighs any possible problems.
I dream of an America where a chicken can cross the road without having it's motives questioned.

 

RE: One More Thought, posted on June 6, 2017 at 10:29:21
KanedaK
Audiophile

Posts: 2519
Location: Brussels
Joined: April 27, 2010
 Well, you gotta put the xover SOMEWHERE... :) these are three way speakers. Think Klipsch LaScala with better everything. I think having a single driver (compression driver covering 400-6KHz is a good thing. Then ther

 

RE: Analog ?, posted on June 6, 2017 at 10:55:25
Head_Unit
Audiophile

Posts: 269
Location: Los Angeles
Joined: February 5, 2004
 I'm not sure how you are measuring the 150 Hz bump, but I wonder if it is the horn (as someone else said) or the room. Is there still a bump if you measure right in the horn throat? Well, it can be hard to separate horn vs. room since the room loads the horn and walls can act like an extension. I guess I'd be curious if there is a bump at 150 Hz out in a free field. But maybe that is so much trouble to move everything that EQ is easier!

 

RE: Analog ?, posted on June 6, 2017 at 16:04:15
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 I agree with you Don.

Modern digital processing from Microphone input to DACs is in 32 bit/96 Khz. MINIMUM these days.

135 db dynamic range with 24 bit resolution is a million time better than any analog device at both ends of the chain.

Those that proclaim otherwise are afraid of the ABX box that would prove them so totally misguided.

 

RE: Analog ?, posted on June 6, 2017 at 16:44:32
djk
Manufacturer

Posts: 6135
Joined: June 17, 2000
 " I guess I'd be curious if there is a bump at 150 Hz out in a free field"

photo LaScala.gif

A simulation of a LaSala type box with two different drivers, both showing peaking around 140hz or so.

 

RE: Well said, posted on June 8, 2017 at 06:31:46
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 Very well said. Acoustical problems need to be fixed acoustially for best results.

Taming the inherent +7db 140 Hz. (annoying) midbass peak in the short horns like the FH1/LaScala just requires the opposite "pull down" in an affordable device like the Behringer 24/96 DCX.

Tiny delay with great improvement in sound= best trade=off.

 

RE: One More Thought, posted on June 9, 2017 at 08:33:26
Inmate51
 Ah, I see. Yes, taking a compression driver down to 150 Hz is not a good idea, unless you enjoy replacing diaphragms.

This actually gets to one of the basic problems with such speaker systems. A 12" or 15" woofer should not be running up to 500 or 1000 Hz. Too much mass, and, the transition from it to the midrange driver doesn't match well dispersion-wise, resulting in acoustical problems with the reverberant sound field.

:)

 

RE: One More Thought, posted on June 9, 2017 at 19:45:23
claudej1@aol.com
Audiophile

Posts: 817
Location: Detroit
Joined: August 17, 2007
 It depends on the woofer and the horn. A pretty good assumption, generally, but there are exceptions that can be measured and simulated.

 

RE: One More Thought, posted on July 12, 2017 at 17:11:04
Arya
Audiophile

Posts: 16331
Joined: July 30, 2000
 I have Altec 9846-a. Horn is 511-b and the woofer is 411b crossed over at 500Hz. Beautiful integration of both. Horn and the woofer are so close to each other, 9846 is considered a point source acoustically.
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