Which EQ to buy/use for IB cal

**IBorBox** · **01-19-08, 12:10 PM**

Hi folks! New to this forum. I have attached a graph of my system output taken at roughly my sitting position which is 10-12 feet from my IB (4 Tempest-X manifold) and located behind my TV. I used the test tones and spread sheet provided on this website (Thank you!). I used the test tones from 10 Hz on up. My original goal was flat to 15 Hz on the low end. I could barely hear the 20 Hz tone so I was satisfied with my unEQed results. Which EQ would best suit my needs as I am somewhere between a casual and critical listener (BFD, Rane,...). Thanks!!

**brucek** · **01-19-08, 12:54 PM**

The BFD is inexpensive and quite effective for sub equalization. I would go with the BFD.

It would be a good idea to switch to using REW. It makes it much easier to get the correct filters to use in the BFD.

brucek

**IBorBox** · **01-19-08, 01:09 PM**

Thanks Bruce. I probably should have done the graph with my sub alone which I will do now. The BFD looks like it may need a hum filter or something? What would you recommend to go along with the BFD to get up and running considering my equipment is not Pro "type" stuff (no XLR)? Which Behringer would you recommend?

**brucek** · **01-19-08, 02:54 PM**

Quote:

The BFD looks like it may need a hum filter or something?

Some people do experience a hum from a ground loop when they use a BFD, but most don't. I would install it first, and then see if you need to address that.

Quote:

What would you recommend to go along with the BFD to get up and running considering my equipment is not Pro "type" stuff (no XLR)?

The BFD adjusts automatically for both balanced and unbalanced input and output, depending on the type of connector used, so that's not an issue. You would use (RCA to 1/4" TS phone) cable.

The BFD also has a switch to go between pro and consumer level. Again, not an issue.

Quote:

Which Behringer would you recommend?

See here.

brucek

**IBorBox** · **01-19-08, 03:35 PM**

Thanks again Bruce!

**IBorBox** · **01-20-08, 04:26 PM**

So to use a BFD I would need a connector that connects rca to XLR or 1/4-inch (don't know what the differences are between these connections either physically or functionally) and another to reverse for output? In order to use REW I would need a mic (ECM8000?), a mic preamp (recommend?) and a cable to go from the mic (what connection is on the mic?) to the 3.5mm connector on my laptop sound card? Any suggestions as to what I would need would be appreciated. I am running my IB using a NAD 2200 amp. I've noticed that my power meters were not responding the same for the left and right channels. I noticed this years ago when I was using the amp to run my stereo speakers (Pre home theater). I have been driving my IB as a "stereo" sub. Two drivers each powered by one side of the amp (8 ohms nominal per side). I believe the amp is miscalibrated to where one side is putting out significantly more power than the other (4/5 db). So I bridged the amp so I could drive all 4 drivers off the same channel (4 ohm nominal). Now I can't lower the sub volume enough using the sub setup in my receiver. Does the BFD allow attenuation of the output to correct this situation? I would estimate the output is 6/7dB too hot. I saw there is a -4 and a +10 db compensation but is there an overall level matching capability within the BFD? Thanks!!!

**01-20-08, 05:09 PM**

Hi you could check out the Behringer cx-3400 that will let you lower the output to you sub amp no problem as the bfd will only let you choose between the two settings you mention, -4 and +10 db.

I 've used a cx-3400 for ages and find them pretty good, also it has delay which is helpfull, also available which is even better is the Behringer dcx-2496 it has auto phase setup which uses the Behringer test mic.

Both are quite cheap.

**brucek** · **01-20-08, 05:44 PM**

Quote:

So to use a BFD I would need a connector that connects rca to XLR or 1/4-inch (don't know what the differences are between these connections either physically or functionally) and another to reverse for output?

XLR and 1/4"phone plugs are only physically different, not functionally. You can simply use a simple RCA to RCA cable with an adapter like the one below, that can be had from Radio Shack.

Quote:

In order to use REW I would need a mic (ECM8000?), a mic preamp (recommend?) and a cable to go from the mic (what connection is on the mic?) to the 3.5mm connector on my laptop sound card? Any suggestions as to what I would need would be appreciated.

You can use a Radio Shack SPL meter or better, a Galaxy CM140 SPL meter, or the ECM8000 which uses the Behringer XENYX 802 preamp.

All these output line level signals, so the standard microphone input on a laptop is not suffice. It has to have a line-in. most don't, so an external USB soundcard is required. Very cheap to buy..

Quote:

Does the BFD allow attenuation of the output to correct this situation?

No, it's a unity gain device.

Quote:

I saw there is a -4 and a +10 db compensation

This is merely a selection of operating level. It has no effect on the level of the signal. It basically determines maximum level..

brucek

**IBorBox** · **01-20-08, 06:24 PM**

OK, it seems as though this will take quite a bit of misc "stuff" to better optimize my setup using REW. Since I will most likely only be doing this once (yeah right), maybe I should see what I can do just using the manual method I used to generate my first graph. Since I need to do some signal attenuation, I should probably look into another device which will allow attenuation and bandwidth adjustment (suggestions?). Unless I'm looking at this too simplistically, I can probably get much better than it is now and somewhat close to the REW approach. Thanks!

**brucek** · **01-20-08, 07:25 PM**

Quote:

Since I need to do some signal attenuation, I should probably look into another device which will allow attenuation

I'm a bit confused why you are experiencing this level problem. Bridging an amplifier caused the level to increase?

brucek

**IBorBox** · **01-20-08, 08:10 PM**

Yes, it increased. My sub level was previously at -18 and only goes to -20 in the receiver. What I think happened was since my channels on the amp are not equal, 2 of the drivers where getting less power and were not significantly contributing to the SPL. When I bridged, they all are seeing the same output. Also there might be a small delta in gain by reconfiguring the amp (2 channel --> bridged).

**IBorBox** · **01-21-08, 08:55 AM**

Maybe I could get a couple of these 6db inline attenuators http://www.partsexpress.com/pe/showd...number=266-234 to bring the levels down to within the range of my receiver so the behriger is again an option. Thoughts?

**brucek** · **01-21-08, 10:03 AM**

Yeah, that would work. With the small attenuation provided, it likely has poor output impedance, so place it at the sub amp and not at the receiver....

brucek

**IBorBox** · **01-21-08, 04:58 PM**

Thanks Bruce, is the version 1.4 firmware a good way to go with the 1124P? I'm not sure what the midi feature does so I wanted to find out if it was needed/nice to have/or what. I realize this may too specific of a question. Thanks

**brucek** · **01-21-08, 06:45 PM**

Quote:

is the version 1.4 firmware a good way to go with the 1124P?

The V1.4 firmware fixed a bug in the midi. REW can communicate with the BFD by passing the filters instead of entering the filters by hand. I've only ever entered by hand, since I think I can enter them faster than you can connect the midi cable. Some people seem to enjoy the midi connection method though..

New BFD's would come with the V1.4, but old stock in a music shop may not. It's easy enough to test at the store before leaving...

brucek

**IBorBox** · **01-21-08, 08:27 PM**

Thanks again! Seems as though the midi function is nice to have but not essential.

**IBorBox** · **01-25-08, 11:28 PM**

Just got my 1124 set up. The REW software is awesome, Nice job! My 1124 had a date code of 0706 which I assume is June of 07 (?). Is this version 1.4? I can see why entering using REW/MIDI would be nice. I used my Radio Shack meter tied into my sound card in a Dell semi-performance oriented desktop. Wasn't as straight forward initially as I thought it would be but made more sense once I got thru it. I used 12 filters to get within +/-2 dB. I still need to lower my input into my amp to the lowest setting in my receiver (-20). I was barely getting two LEDS flashing on the display for input level. My output of the sub was +6/7 dB of mains when testing with the built in test tones.

**Wayne A. Pflughaupt** · **01-28-08, 02:30 PM**

Highly doubtful that twelve filters are actually needed. You might want to take a look at this article.

Regards,
Wayne

**IBorBox** · **01-28-08, 08:49 PM**

Interesting article Wayne, thanks. I will look at it again. It was challenging getting 12 filters to work.

**IBorBox** · **01-28-08, 09:03 PM**

I'm still experiencing to high of a line level into my amp with the sub out level of my receiver set at the minimum level. I tried the 6-dB attenuators mentioned above but I got a significant hum (I put them on the amp input). So I'm looking for a variable volume control that will allow me to get a higher input into my BFD but allow me to control the BFD output into the amp without experiencing the same hum. I was looking at the Reckhorn B-1 or F-1 as the least expensive solutions for volume control. Any other options or these reasonable devices to accomplish volume control without the hum of the passive line attenuators I tried? Thanks all for your help.

**IBorBox** · **01-30-08, 08:17 PM**

Any opinions on the reckhorns or equivalants?

**Sonnie** · **01-31-08, 01:46 AM**

The ART Clean Box might do what you need. The ART Clean Box ll will eliminate the hum.

**01-31-08, 05:50 AM**

Hi
Did you check out the prices on the Behringer cx-3400 crossover i believe they are quite cheap in the US, there is one on e-bay at $1 at the minute,
it should eliminate the hum if you remove the ground pin on the xlr input side ( has for me ) also it will control the volume very easily.

They look much better quality than the reckorn ?

**brucek** · **01-31-08, 07:12 AM**

Quote:

Any opinions on the reckhorns

I did a small discussion here...

**WmAx** · **01-31-08, 11:05 AM**

Quote:

stephenb1 wrote:

Hi
Did you check out the prices on the Behringer cx-3400 crossover i believe they are quite cheap in the US, there is one on e-bay at $1 at the minute,
it should eliminate the hum if you remove the ground pin on the xlr input side ( has for me ) also it will control the volume very easily.

They look much better quality than the reckorn ?

I have at one time used a CX3400 Behringer. It performed transparently with no audible noise(unless you put your ear about 6" from the speaker, then you could hear a slight 60Hz hum - but keep in mind this was also used in unbalanced configuration in my case). As far as quality, what I saw inside was a larger than needed toroid transformer, high quality Alps potentiometers throughout, jrc 4556 op amps, and what appeared to be the standard good quality electronic components you would expect to find in a good piece of studio gear. The main PCB is very short and very wide, mounted to the back of the front panel, with two smaller PCBs hanging from this to hold some stacked pots. Primarily surface mount components, with the main part of the chassis empty for the most part. Ribbon cables connect the front PCB to the back PCB that contains the jacks/ports and power supply filter. The only issue I had was there was no muting circuit during power/on/off. There for a subtle to moderate 'thump' occurs.

-Chris

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