Time for a PEQ

[Highlander]

Dear all,

In light of my (latest) living room's poor acoustics, a direct function of it's limited 12'x14' size, I've decided that action is needed to address the issue. My room treatment on its own is not enough and therefore I'm looking to buy a PEQ.

Right at the outset I'll declare that I'm leaning towards the Behringer DCX2496 as consistently recommended by WmAx. That said, I'm open to any recommendation that others feel can compete with the Behringer. Price is unlikely to be an issue. In addition, note that although I have a 7.2 system, I am principally looking to EQ music. In other words, 2-channel CDs.

I currently use the coaxial digital and i-link outputs from my Universal player as CD and DVD inputs respectively to the receiver. My Yamaha Z9 receiver has pre-outs for all channels though at present only the two sub-outs are used. The receiver also has pre-amp inputs for the Centre and two Front speakers.

How would a PEQ be connected into the hi-fi? Do I leave the player inputting into the receiver, take the receiver's Front pre-outs to the PEQ, feed the PEQ's output back into the receiver's pre-amp inputs, there to be amplified and sent out EQ'd to the Fronts and, also EQ'd as pre-outs to the subs?

Any help/advice would be appreciated.

 

[zumbo]

Wouldn't YPAO be easier? Don't you need a new receiver anyway?

 

[Highlander]

Wouldn't YPAO be easier? Don't you need a new receiver anyway?

I presume you're being funny?

YPAO is waaay too coarse and no, I love my Z9, more so than the new Z11 so no, I'll not be getting a new receiver thank you very much Zumbo.

 

[OttoMatic]

Hi there,

I use a Behringer BFD1124. The BFD2496 is very simiilar to the 1124, and has slightly better specs. However, I believe it only has one preset; if you are interested in applying different EQ for movies and music, you might want more than one preset. The 1124 has ten presets, and is widely used and supported for PEQ of subs.

I think the DCX2496 is crossover that has PEQ. If you don't need the crossover part, and you may well not, the BFDs may be better choices.

I use my 1124 for apply two different sets of filters: one for movies and one for music. The movie EQ path is the easiest: go from the sub out on your receiver to the BFD, and from the BFD to your sub. The BFD is a stereo PEQ, but you only really need one to EQ a sub; I use the "left." If you are using two sub outs, you can certanly EQ both the same (using the L and R channels of the BFD), or you can use a splitter at the output side of the BFD. Either way will work. Apply filters in the BFD using REW. REW is a great tool, and is very useful to determine your sub's and room's frequency response. It also interfaces with the Behringer products via MIDI.

My preamp does not offer a signal at the sub output when listening to two-channel stereo. Therefore, I have to use the L/R outputs from the preamp to apply bass PEQ for music listening. I had to do a little hoop-jumping to accomplish this. I send the preamp's L/R balanced signals to a little mixer that then generates a mono signal. That's then fed to the "right" channel, which has a different set of filters than the "left." I use a "house curve" on the "left" for movies, and keep a flatter curver on the "right" for music. Also, since the L/R signal coming from the preamp is full-range, I have to somehow apply a low-pass filter to it (I'm using an IB sub w/ a pro amp, so there's no LPF there). I simply made a LPF using some of the filters of the BFD; there are twelve filters per channel, and I certainly didn't need that many to get a very reasonable response for my bass.

One final nicety that I implemented is the ability to switch between "movie" and "music" EQ. I did this by using a little remote controlled preamp by Chase Technologies called the RLC-1. This just allows me to switch between the L and R outputs of the BFD. It also allows me to control volume after the BFD, which is what you want to do in order to keep the input to the BFD at a predetermined level (in order to maximize SNR and dynamic range capability).

Anyway, that's how I'm doing it for two different signal paths at the same time. I highly encourage anyone seeking bass frequency response improvements to try out the BFD.

 

[zumbo]

I presume you're being funny?

YPAO is waaay too coarse and no, I love my Z9, more so than the new Z11 so no, I'll not be getting a new receiver thank you very much Zumbo.

LOL! That was funny to me. Good luck!

 

[Highlander]

Firstly, thanks for the meaty reply OttoMatic.

I use a Behringer BFD1124. The BFD2496 is very simiilar to the 1124, and has slightly better specs. However, I believe it only has one preset; if you are interested in applying different EQ for movies and music, you might want more than one preset.

Probably not. After all, once I've sorted out the room's acoustic problem areas, I could just use Yamaha's numerous music/movie DSP effects to shape the sound to my liking.

I think the DCX2496 is crossover that has PEQ. If you don't need the crossover part, and you may well not, the BFDs may be better choices.

Good point. I have to admit that it's the PEQ part that I see being of greatest use to me. Unless I'm forgetting why a crossover part would be advantageous too...

I use my 1124 for apply two different sets of filters: one for movies and one for music. The movie EQ path is the easiest: go from the sub out on your receiver to the BFD, and from the BFD to your sub.

Gotcha, but if I use a PEQ in the way I described above, wouldn't I have the advantage of being able to EQ not only the sub, but the portion of sound coming out of the Fronts and, should I choose, the Centre, given that I have pre-amp inputs for these channels on the Z9?

Apply filters in the BFD using REW. REW is a great tool, and is very useful to determine your sub's and room's frequency response.

I already have ETF for measuring my room's response to 1Hz accuracy so I'm sorted in this respect.

One final nicety that I implemented is the ability to switch between "movie" and "music" EQ. It...allows me to control volume after the BFD, which is what you want to do in order to keep the input to the BFD at a predetermined level (in order to maximize SNR and dynamic range capability).

Why do you want to keep the BFD at a predetermined level? Surely you want the volume feeding into the BFD to change in line with the volume on the amp no?

Good luck!

Cheers.

 

[OttoMatic]

Firstly, thanks for the meaty reply OttoMatic.

Sure, man, my pleasure.

Probably not. After all, once I've sorted out the room's acoustic problem areas, I could just use Yamaha's numerous music/movie DSP effects to shape the sound to my liking.

OK, one preset is cool. The reason I brought it up was because many people will boost bass for movies (they sound kinda flat and boring when using a truly flat frequency response). But most music people want a flat response for music (myself included).

Good point. I have to admit that it's the PEQ part that I see being of greatest use to me. Unless I'm forgetting why a crossover part would be advantageous too...

Yeah, you probably won't need a crossover. A BFD will be fine.

Gotcha, but if I use a PEQ in the way I described above, wouldn't I have the advantage of being able to EQ not only the sub, but the portion of sound coming out of the Fronts and, should I choose, the Centre, given that I have pre-amp inputs for these channels on the Z9?

I had a quick look at your receiver. What you need to be able to do what you're describing is a "tape loop." I didn't see it called out in the specs, but it may be described somewhere in the manual.

You're talking about going into the receiver digitally (e.g., from a CD player), going out the analog preamp outputs, into the EQ, and then out of the EQ and back in the preamp inputs on the Z9. The problem is that you'd have to select the preamp inputs as the input to be used. Once you do that, you've no longer selected the CD as the input, and you'll have no sound.

If you have a tape loop, you can do it. Otherwise, you can't.

Other options -- use the CD player's analog outputs to feed the EQ and then go out of the EQ into any analog input on your Z9. That will definitely work, but will have the following drawbacks:

1. can't EQ other audio sources, only the CD player
2. can't EQ digital sources for movies, etc.

So, all that said, I'll also throw in this -- most people using EQ target it for sub-duty only, for these reasons:

1. difficult to measure room response as frequency increases. Once you get >200 or >500 Hz or so, the response gets really ragged. This is because there's just so much audio bouncing around the room that it becomes a mangled signal.
2. If the measured signal is ragged, then you can't create filters to "fix" the response
3. an added A/D/A stage
4. any other noise introduced to the "main" signal from the Behringer equipment. These devices have been cited to introduce "grain" and other noise into the system. Of course, that noise is much less audible in the sub range, and many people are happy to use this stuff for sub duty.

You noted that you're using room treatments already. I'm curious as to your current complaints about your sound. What don't you like? Also, can you post a frequency response plot?

Now, I'm not trying to tell you not to EQ your mains if you want to, and I'll be happy to keep chatting about general setup and measurements and such. Just noting that most people don't do it because of the downfalls.

I already have ETF for measuring my room's response to 1Hz accuracy so I'm sorted in this respect.

That's looks like a cool tool! The reason I brought up REW, though, is that it's so well-integrated with the BFD. It'll measure, calculate filters and then upload those filters to the BFD -- all in about 10 seconds. If you're a tweaker and measuring and setting filters in a loop, it's quite handy. OTOH, if you're happy with what you have, stick with it! You'll just have to enter the filters to the BFD by hand (as well as do the calculations for f, BW and gain).

Why do you want to keep the BFD at a predetermined level? Surely you want the volume feeding into the BFD to change in line with the volume on the amp no?

Yeah, sorry, I think I wasn't clear about that. What normally happens is that we set the input to the BFD (by using the output levels of the preamp) such that they're at their highest level that you would ever listen, just prior to where the inputs of the BFD will clip.

To do this, I usually take a real bass heavy movie (yeah, I'm sub-focused on this, but the concept will apply if you want to EQ full range) and crank it up to as loud as I would ever possibly listen. I can then adjust the output of my preamp until the loudest parts are just bumping into the red of the measured input to the BFD. I now have the greatest amount of dynamic range and the highest SNR at the BFD input. Of course, that statement applies only at that loudest point, but it's the best we can do.

You're right -- as you control your volume knob, the input level to the BFD will indeed change; it has to. The thing I don't want to do is say -- this movie is too bassy, and turn down the sub output level of my preamp to knock off some of the bass. You want to do that after the EQ's output. And that little RLC-1 allows me to do that.

If you've ever set up a device to record a live input, it's a very similar process. Think of setting up a tape recorder -- you have someone talk into the mic and you watch the meters. Then continue to adjust the input leve at the loudest level that's going to come into the mic. That way you're getting up to the higher end allowed by the recording device without clipping it. Then, when it's too loud at the speakers, you turn down the volume knob, and not the input level. Anyway, something like that.

All right! That's enough for now.

 

[Highlander]

Other options -- use the CD player's analog outputs to feed the EQ and then go out of the EQ into any analog input on your Z9. That will definitely work, but will have the following drawbacks:

1. can't EQ other audio sources, only the CD player
2. can't EQ digital sources for movies, etc.

On point 1; not a problem as I use my Universal player for both CD/DVD playback. The only other input I use is Tuner and that doesn't warrant EQing.

On point 2; I suppose I could simply keep the i-link feed to the Z9 for DVDs and have CDs EQ’d by taking the analogue-outs from the Universal player to a PEQ but this seems a poor way to do things when by inserting a PEQ between the Z9 and subs I get any and all bass content below the crossover (80Hz) from any source EQ’d.

You noted that you're using room treatments already. I'm curious as to your current complaints about your sound. What don't you like?

I can audibly hear a swell of bass at low frequencies, almost certainly the room’s modes, and a lack of bass that in my previous (larger) living room I heard. Placing my ear next to a sub confirms that they're there but are being cancelled out at the listening position.

Also, can you post a frequency response plot?

Actually, I've not yet finalised the acoustic absorption layout of the room so I can't provide a 'this is the best I can get at present' plot. Having said that, I’ve got a feel from various tests on the effect exerted by the room (here's a typical example!) and I'm in absolutely no doubt that I’ll be unable to achieve this, the response in my last living room.

Now, I'm not trying to tell you not to EQ your mains if you want to, and I'll be happy to keep chatting about general setup and measurements and such. Just noting that most people don't do it because of the downfalls.

I agree that the towers are less of an issue than the subs as a result of Bass Management. However, I would ideally like to be able to EQ my towers – whether the low frequencies above the crossover or any other region of the audible spectrum I choose.

The reason I brought up REW, though, is that it's so well-integrated with the BFD. It'll measure, calculate filters and then upload those filters to the BFD -- all in about 10 seconds. If you're a tweaker and measuring and setting filters in a loop, it's quite handy. OTOH, if you're happy with what you have, stick with it! You'll just have to enter the filters to the BFD by hand (as well as do the calculations for f, BW and gain).

So noted.

Generally speaking, how would you recommend I wire things up if I wish to EQ my towers and subs? Do I simply insert the PEQ between the Universal player and Z9? Also, I note that in the past WmAx has mentioned that the DCX (and presumably the BFD too) may need to be used in conjunction with a potentiometer because these are Pro bits of gear and the output signal is of greater magnitude than with consumer products. Do you have any recommendations for good consumer PEQs? Surely someone must make them.

 

[Highlander]

So nobody knows any consumer PEQs they'd recommend?

 

[OttoMatic]

Hey Robbie,

I meant to respond on Sunday, but I didn't find the time to make a good one.

Anyway, I'll offer a few quick comments here.

Personally, I'd go with one of the BFDs (either 1124 or 2496, your choice). You can definitely insert it in the path between CD player and receiver, and you will be able to apply EQ to the entire signal path, thereby affecting your mains as well as your sub.

The BFD1124 is frequently available on eBay for well under $100, so it's not much of an investment if you don't like it.

I see your frequency response plots, and I do agree that you can do better. You "old" one looks pretty decent.

If you're looking for options other than Behringer, I think Rane and TagMcLaren both make "better" devices. I have zero experience with either, but I believe they will have better audio quality. I believe they will also cost a lot more.

That's it for now.

 

[Highlander]

Cheers Otto. Seems like it's just you and I.

...I'd go with one of the BFDs (either 1124 or 2496, your choice).

I've taken a look at the back of both the BFD Pro1124P and BFD ProFBQ2496 and have a couple of questions:

1. Both units have "Operating Level" buttons to swith from "home recording level (-10dBV) to studio level (+4dBV)". Does this provide an easy means to get around the level difference between commercial and pro pieces of gear I noted at the end of my last post? In other words, does the switch mean that the BFD will send out a line level voltage my commercial gear will be happy with?

2. Don't you think it strange that, as far as I can see at least, only analogue inputs are provided (not sure if you can go from coaxial digital to MIDI)? I mean, presumably the first thing the BFD does is digitize the signal so as to shape it in the digital domain which, I understand is far easier to do than in the analogue domain. If so, why don't Behringer provide digital inputs?

I see your frequency response plots, and I do agree that you can do better. You "old" one looks pretty decent.

Decent?! Decent?! It's a miracle given the constraints I had!

If you're looking for options other than Behringer, I think Rane and TagMcLaren both make "better" devices. I have zero experience with either, but I believe they will have better audio quality. I believe they will also cost a lot more.

Time to do some fishing.

 

[OttoMatic]

Hey,

1. In general, yeah, the BFDs play pretty well in these situations where there's a mixture of home and pro gear. I'm going from a Cary Audio Cinema 11 to the BFD to a Behringer EP2500 and have no problems. I think my sub trim is only a few dB hot from 0, and the amp gain is at about 12 o'clock. There may be some corner cases where people run into problems, but many people use that device in this type of setup. I believe it's generally setting an input circuit to accommodate the levels coming from the particular piece of equipment. The BFD is a unity gain device, so if there are no filters applied, then there's no change at the output (i.e., input level of x = output level of x).

2. In general, you can't send a "normal" S/PDIF digital signal to a MIDI input; they're totally different. Yes, you are right that there are only analog inputs on the BFD. I do agree that the BFD should have digital inputs, and that it will almost immediately sample the analog signal. I'm not sure why it doesn't have digital inputs, especially if you were to use a number of these types of devices in series in a recording or pro-audio path (not necessarily a bunch of BFDs in series, but just a bunch of "devices" in series. It would be detrimental to have so many A/D/A stages). I do believe that some of the other Behringer products offer digital I/O, but I'm not sure which; perhaps the DCX2496.

 

[Highlander]

Some more questions if you don't mind:

1. Can one buy stock RCA to XLR/¼"TRS interconnects?

2. You wrote: "...The BFD is a unity gain device, so if there are no filters applied, then there's no change at the output...". Are you saying that there's no need for an external potentiometer in the event that the line level voltage from the BFD is too high for the Z9 (assuming the BFD is placed between the Universal player and Z9) and that a 'filter' feature of the BFD can reduce the voltage outputted from it (presumably the 'filter' is simply a form of gain)?

3. You wrote: "I do believe that some of the other Behringer products offer digital I/O, but I'm not sure which; perhaps the DCX2496." The BFD appears only to have two inputs whereas the DCX2496 has three, one of which can be used as a digital AES/EBU input. Does this mean that the DCX2496 can accept the coaxial digital signal from my Universal player using an interconnect with an RCA jack at the player end and XLR jack at the DCX2496 end?

Thanks for all your help thus far Otto.

 

[OttoMatic]

1. Yeah. I think Monoprice will have them, and probably RadioShack. The 1/4" variety will only be T-S (splitting hairs a bit).

2. Correct, unless you apply a lot of positive gain. If you only "cut" (reduce gain), then the input back to the Z9 will only be lower than it would be normally. If you apply positive gain, then the output of the BFD/input to the Z9 may (most likely, "will") be greater than normal. I think you'll be OK on this part.

3. Well, I believe that the AES/EBU signal is a S/PDIF signal. But, as you allude, it's an XLR connector. I'm not sure if it's actually balanced or not. I don't have a good answer, so I'll just say "maybe." You'd have to check out the spec for S/PDIF for the various types of connectors. I'd start with Wikipedia...

 

[Highlander]

Correct, unless you apply a lot of positive gain.

Ah, then I should be alright in this respect since it's generally advised, especially with regard to low frequencies, not to boost and only to cut.

...I believe that the AES/EBU signal is a S/PDIF signal. But, as you allude, it's an XLR connector. I'm not sure if it's actually balanced or not. You'd have to check out the spec for S/PDIF for the various types of connectors.

Hmm. Actually I hadn't considered that an XLR type connection would impede the digital signal, only whether an AES/EBU was the same as S/PDIF. I'll P.M. a man who'll hopefully know. If he doesn't, I'll P.M. another.

Will let you know of any developments. Cheers.

 

[WmAx]

I did not read this entire thread. I am replying to a PM from Highlander and posting it to this thread, as this is what Highlander specified to be preferential.

Can you help me out by answering the following, either in the thread (preferable so that others may also learn) or by P.M.?

1. Is the XLR AES/EBU input on the DCX2496 able, through an interconnect with an RCA jack at one end and XLR at the other able to carry coaxial digital from my Universal player to the DCX2496?

No. A matching circuit is required(easy to construct from a few parts; or you could buy a pre-made adapter) to send consumer level to professional balanced reciever AES3 input. The data component of the signal is compatible; the issue is matching impedance and voltage levels.

If you want to make your own adapter, refer to:

http://www.rane.com/note149.html

As for existing passive adapters - you'll have to do a search. For an active converter(that can cross connect almost anything or even change/modify sample rate/bit rate to increase compatibility), refer to the Behringer SRC2496.

2. Besides the Behringer DCX2496 and Feedback Destroyer (BFD), do you have any other recommendations for PEQs, especially commercial PEQs?

The Behringer DEQ2496 is another option. But so far as other manufacturers of DSP devices such as is the issue here, I am not aware of another manufacturer making comparable quality to Behringer for the same general price. I you want to go with another manufacturer, it looks as though you will generally pay substantially more money(2x or more) for comparable quality DSP devices.

3. Thinking for the future, are there any reasons that make it more advisable to get a DCX2496, which I understand is able to implement crossovers and a PEQ, than a BFD which I understand is a PEQ but unable to implement crossovers? In other words, if I'm looking for a PEQ to sort out my rooms frequency response principally in the low frequencies, is the DCX2496's ability to implement crossovers useful? Am I missing where this ability would come in handy?

The DCX2496 would be useful if you ever use components(instead of a receiver) to integrate speakers with subwoofers. Also, if you ever chose to go fully active (make your own speakers or remove the passive crossovers from existing speakers), it's got you covered.

-Chris

 

[Highlander]

Thank you very much WmAx.

I hadn't spotted the DEQ2496. This is looking very promising for the following reasons:

1. It facilitates S/PDIF for both input and output. This greatly appeals to me as I could take an optical (I take it the more robust coaxial type of digital connection wasn't used due to potential problems with cable run lengths?) digital signal from my Universal player to the DEQ2496 and then on to my Z9.

2. There's no messing about (or worrying ) with having to convert line level voltages (even if it is easy) or purchase interconnects with different terminals.

3. The DEQ2496 incorporates an RTA.

4. Although the DEQ2496 has less PEQ bands than the BFD FBQ2496 (10 vs 20), at least ten of the DEQ2496's GEQ bands are below 200Hz and so may well be of practical use.

It is possible that I may in the future feel the need for the DCX2496's crossover features, but it'll be many years at the earliest so I think I can probably rule it out.

Given the general advice from both Otto and yourself regarding significantly more expensive units for only comparable quality, it seems my choice has boiled down to either the BFD FBQ2496 or DEQ2496. I'll browse their manuals a bit further before deciding what to do.

Cheers,

 

[Highlander]

After reading the manual for the DEQ2496, I've a couple of questions for y'all:

1. The DEQ2496 allows the user to select either 'shelving filters' or PEQs as presets. Is a shelving filter the same as a crossover (it reads as though it is)?

2. If I take the (mono) RCA line level output from my RadioShack SPL meter as Mic Input to the DEQ2496 which, going by the manual I'm able to (would need to buy an RCA to XLR interconnect), what line level setting would I use? The permissible range is -14 to +22dBu.

Haven't yet decided (still to read the BFD's manual) but the DEQ is looking better and better all the time. For example, I could be wrong but using the DEQ's pink noise generator as its input I appear to be able to output it optically digitally to my Z9, let it play through the speakers to be picked up by my SPL meter feeding back into the Mic Input of the DEQ to be analyzed by its RTA. How cool is that?!

 

[Highlander]

All,

I'm trying to calculate frequencies from 20Hz upwards in 1/3rd octave steps. I calculate them to be 20Hz, 26.7Hz, 35.6Hz etc...yet this appears to be incorrect.

What am I doing wrong?

 

[Highlander]

Sussed it.