Equalizer update

[mkmelt]

Regarding the BSR 3000 equalizer, I recently picked one up at Goodwill for $20. I did some research and found it was a decent 10 band equalizer that provides for +/- 15db at discrete frequencies, with the added benefit of having a built-in spectrum analyzer and pink noise generator. The pink noise generator can be used with the factory-supplied microphone * for positioning loudspeakers in a room for flattest bass response, equalizing each channel at a given listening position for flattest response, or even setting the recording bias adjustment on a cassette deck.

The BSR 3000 was also sold as the ADC model 315X after BSR was merged with ADC, or so I have read.

The BSR 3000 originally had a suggested retail price of $349, but I have an invoice for a second one I purchased off of eBay that shows that it was sold by DAK for $149. Anyon remember this mail order house that would advertise in audio and electronics magazines with closeout specials on electronics and other toys?

To my ear the BSR 3000 is a very clean sounding unit, so I was not surprised to read the specifications that it has a wide bandwith of 5 ~ 100,000 Hz. When it is switched out of the EQ mode, I can not detect that it is in the circuit of my tape monitor on my amplifier.

A couple of words of caution: First, the owner's manual warns against accidentally plugging in a headphone into the front panel microphone jack.

* Second, the only microphone that is safe to use with the BSR 3000 is the calibrated electret condenser microphone that came with the unit. Do not attempt to use a regular dynamic microphone with this equalizer. If you do, the owner's manual states that unit can be damaged.

Prices are all over the place for the BSR 3000. I paid $20 for a well used but working example at Goodwill, and $35 plus shipping for a very clean unit including the manual and the original microphone. I have seen these go on eBay for as little as $25 and as high as $155, so don't be fooled into paying too much.

[Jahn]

Hmm not a good sign when it ends up being found on a vintage site -

http://www.oaktreeent.com/Stereo_EQ'S_And_Signal_Processors.htm

[gsferrari]

I dont know if there is a way to make sure that left and right get the same EQ'd data...I can do separate L/R and combined L/R EQing with the Behringer.

This should not be a MAJOR issue with speakers but with headphones it can be frustrating to set each channel EQ just right...maybe even impossible.

For whatever it is worth $40.00 is not a big hit and I am being optimistic about the chances that this could do well in your setup. there is no reason why it should sound bad...balancing is the key point to take into consideration here...channel balancing.

[mkmelt]

Do you really think your ears have identical sensitivity at all frequencies? This is highly unlikely.

[gsferrari]

Originally Posted by mkmelt

Do you really think your ears have identical sensitivity at all frequencies? This is highly unlikely.

Exactly - which is why I am not so sure using the autoEQ is a good idea. better to use your ears right? What they can hear means more than what a microphone can hear.

But if you are saying that the Stereo EQ is a good idea because each ear might be different in sensitivity - THEN I AGREE...

Never thought about that...It would frustrate me psychologically to know that the EQ is pumping out different signals on each channel... I like everything to be perfect.

Cheers!

[jhenderson010759]

Even assuming an identical signal is sent to both speakers and the reproduction capabilities of each speaker is also identical, each would almost certainly need to synthesize a different output in order to properly reproduce that signal at your listening station. This is because the overall transfer function of each speaker is influenced by it's environment. For example a drapery may be nearer to one speaker than the other.

So, you should recoil in psychological horror at the prospect of identical signal processing from both equalizer channels.

OTOH, this effect should be substantially mitigated for headphones (except for Van Gough).

[jhenderson010759]

Two questions:
1) Which PC-based MIDI board(s) have been successfully used to interface with the Behringer DEQ 2496? Is software interoperability an issue with MIDI boards, or will any run-of-the-mill midi board do the trick? I'd like to upgrade the firmware on my DEQ and be able to transceive configuration info and equalization settings.

2) I'd like to connect the balanced differential analog outputs of the DEQ directly to my Stax 006t amp. However, I noticed that Stax and Behringer wire the differential hot and cold signals opposite polarity from one another (Behringer wires 2 hot, Stax 3 hot). If a stock, straight-through XLR cable is used, this would result in phase reversal (both channels). Is it worthwhile to rewire the cable/make one from scratch, or is this sonically insignificant? Seems like it wouldn't be a problem, since both channels would be phase-inverted, thus it would not be analogous to a loudspeaker phase incoherancy (which is readily discernable).

Thanks in advance.

[ooheadsoo]

I think the jury is out on that with re: to absolute phase because it's said that nearly all recordings are phase random. That said, some people say they can hear the difference. Go figure.

[ooheadsoo]

Originally Posted by mkmelt

Do you really think your ears have identical sensitivity at all frequencies? This is highly unlikely.

gsferrari, mkmelt's point is that the ear hears differently at each frequency, not from left ear to right ear. Fletcher-Munson curves describe an average of how average humans hear at different levels. For example, in practice, if I EQ the bass of my speakers to be the same level as the mids of my speakers using my ears and I play some music, the bass sounds way out of proportion, much louder than it should be. This is because the ear is less sensitive to bass. The sensitivity of the human ear changes at different volume levels as well. At low volumes, bass is even harder to hear compared to mids and highs, than at loud volumes, etc. A decent microphone with decent FR would be better in this case.

[gerG]

I have used an M-audio firewire interface, as well as a basic Edirol usb midi interface. I really like the latter solution because it is cheap, has built in midi cables, and is highly portable (fits in a back pocket). I use midi-ox as the interface software. The only real issue is getting the speed low enough for the Behringer to cope, since the PC will dump data too fast. The DEQ to DEQ direct trick works incredibly well, making it a snap to synchronize units.

I would not worry about absolute phase too much. Too many things in the system reverse the phase to keep track of it (even which way they put the drivers in the headphones). Since they are AC signals, + is only a phase reference, and it may have been reversed by the time it gets to the terminals anyway. My usual trick in a dynamic system is to feed a DC signal into the input, and see that the driver steps in the positive direction. Although this works like a charm on speakers and dynamic cans, I would not try it on electrostatics, unless you have a laser interferometer handy. If you do have a LI handy, then you have the complication of the signal, which we would prefer to keep digital. I would suggest generating a timed square wave of 1 second duration stepped from zero to positive with an amplitude well under digital clipping. If you don't have a LI, go with soldering up both sets of cables and see if you can hear the difference. Alternatively you can build a box with a phase reverse switch. Put one on each channel and you can even see what they sound like with a side to side phase mismatch (it is nothing like speakers).

I am not going into ears not matching (one of mine is lower than the other, but fortunately my brain is in crooked, so it all works out). It does not matter for my purposes. I am using the DEQ to compensate for defficiencies in the headphones, not in my ears.


gerG

[Jahn]

Thanks for the history on my equalizer by the way! Hmm, it can be used to even out the bias in a tape deck - i wonder if it can do the same for my turntable, which might pick up some odd stuff from its needle. Well in that case I won't have to get a mic for it, since i dont have speakers - I'll just use the pink noise to help even out the turntable signal.

good call on the mic - no dynamic mics eh? just a condenser. i wonder if a non-factory condenser mic can be used for recording purposes through the equalizer - not just to pick up signals for pink noise use.

[jhenderson010759]

Originally Posted by gerG

<excerpt>... If you do have a LI handy, then you have the complication of the signal, which we would prefer to keep digital. I would suggest generating a timed square wave of 1 second duration stepped from zero to positive with an amplitude well under digital clipping.
gerG

I guess I'll compromise and use some stock XLRs for now. But, I'll ask my wife for a laser interferometer for Christmas, so that I can resolve this issue once-and-for-all (www.lasermotion.com appears to have some good deals on used equipment). I'm sure one of the kids would be willing to sleep under the Mohave granite optical isolation table, instead of their bed, as their bedroom morphs into a suitable laboratory annex .

[mkmelt]

[I wonder if it can do the same for my turntable, which might pick up some odd stuff from its needle. I'll just use the pink noise to help even out the turntable signal.]

If you had a stereo test record that included a band of pink noise, you could see the playback response, but the resolution is fairly coarse because there are just 10 center frequency indicator bands for the entire audio spectrum, and the smallest increase or decrease that can be displayed is approx. 2db.

[good call on the mic - no dynamic mics eh? just a condenser.]

Here are the original microphone specs:
Element type: Electret condenser
Directivity: Omnidirectional
Impedance at 1Khz: 600 ohm
Sensitivity 0db = 1V/microbar, -70db
Frequency Response, Compensated: 50 - 13,000Hz
Bias: 1.5V DC supplied by EQ 3000

Note: Connect the supplied microphone only, use of other microphones, i.e. dynamic type etc., will damage your system.

[I wonder if a non-factory condenser mic can be used for recording purposes through the equalizer - not just to pick up signals for pink noise use.]

The mic is not stereo, but I don't see why you could not feed the output from the mic to a tape deck via your amplifier.

[gerG]

Jim, lol. Those granite tables are awfully cold. Do not annoy your wife.

Another thought, you could do the same square wave trick, but use a mic to pick up the pressure offset (with headphone coupled to something to seal the cup). Of course, now you have to figure out if your mic/preamp/AtoD invert the phase. For something that seems so simple at first, headphones can sure get complicated. Better to follow the advice of the guru and just enjoy the music. While you do that I will think up another absurd way of figuring out phase on ES cans

Jahn, good luck with your new toy. I haven't joined in the discussion because I am not familiar with that unit, so I have nothing useful to contribute (although that does not usually slow me down). You may also want to experiment with some of the PC based equalizers out there.

gerG

[ooheadsoo]

Hm, what good PC equalizers are there out there? If any are free, I'd like to check some out.