MBM12 & Delay

[E_M]

Hey

I currently have one HSU MBM12, and 2 x DIY subwoofers.

The HSU MBM play from 50-80hz.. and I have a lowpass on my DIY subs at 50hz.

Both the MBM and one of the DIY subs I have are placed nearfield. The DIY sub is like 1m away from the MBM. The second DIY sub is 5m away from the MBM.

On my DCX2496, should I set the distance on the NEARFIELD DIY sub to 1m (since it is 1m away from the MBM), and 5m on the other DIY sub? Is this the correct way of setting the delay ?

[bsoko]

Hey

I currently have one HSU MBM12, and 2 x DIY subwoofers.

The HSU MBM play from 50-80hz.. and I have a lowpass on my DIY subs at 50hz.

Both the MBM and one of the DIY subs I have are placed nearfield. The DIY sub is like 1m away from the MBM. The second DIY sub is 5m away from the MBM.

On my DCX2496, should I set the distance on the NEARFIELD DIY sub to 1m (since it is 1m away from the MBM), and 5m on the other DIY sub? Is this the correct way of setting the delay ?

Can't answer as I have a Anti Mode 8033 and more info about it and discussion here: http://www.avsforum.com/avs-vb/showthread.php?t=1028464.

It does the same thing that you are doing manually only it is full automatic and takes about 5 minutes to complete it's program. Then you're good to go. It does equal the BFD and is better than the SMS-1.

Bill

[E_M]

Im looking through threads at that forum quite often.. don't know how I missed this one! That little device seems to be an awesome subwoofer tool! Doing things automatically just makes everything so much easier :) I might try it out some day. But for now - I need to set the delay manually on the DCX2496, and I hope someone can give me some pinpoints there :)

[bsoko]

Im looking through threads at that forum quite often.. don't know how I missed this one! That little device seems to be an awesome subwoofer tool! Doing things automatically just makes everything so much easier :) I might try it out some day. But for now - I need to set the delay manually on the DCX2496, and I hope someone can give me some pinpoints there :)

See if yuou can PM John on that thread. He's the guy that ended up doing the comparing of the Anti Mode and BFD with the charts.

Bill

[mojave]

The delay is used to compensate for for all speakers/subwoofers that are closer than the furtherest speaker/subwoofer.

How are you connected to the DCX2496? Are you using the subwoofer output of a receiver? Did you set a delay in your receiver for the subwoofer output?

If you are using a receiver and all the subs/MBM-12 are closer than the mains, then I would recommend setting the subwoofer delay in the receiver to 0 ft (or 0 ms). Now use the delay setting in the DCX2496 to set your delay based on the difference of the subwoofers and MBM-12 from the main speakers minus 1 ft for the delay caused by routing through the DCX2496. For example, if your main speakers are 8 ft from your sitting position and the MBM-12 is 3 ft, then your delay is set to 4 ft (8ft - 3ft - 1ft).

If you have a sub that is further than the mains, then set the mains to their distance (8 ft.) and the subwoofer to the furthest sub minus 1 ft for the DCX2496 (11 ft - 1 ft = 10 ft) in your receiver. Now you need to enter in the delay in the DCX2496 for the other sub/MBM-12 based on the distance from the furthest sub minus 1 ft for the DCX2496's delay. If the MBM-12 is 6 ft closer than the furthest sub, then the delay would be 5 ft.

You should be able to use what I wrote to figure out other scenarios as well, but let me know if you need more help.

Are you also using your DCX2496 for parametric equalization and digital crossovers?

[E_M]

Yes im using the DCX2496 as an Xover/PEQ, but only for my subs (HP/LP and some EQ).

I run all the subs through the DCX2496, which is connected to my receivers subwoofer preout (Xover at 80hz).

It's not possible for me to adjust 'delay' with my current receiver.. but tomorrow I will get a new receiver (Yamaha RX-v1800) - maybe it is possible on that receiver.

Setup is something like this:
http://img29.picoodle.com/img/img29/4/6/24/f_stuem_30f58b5.png

Sub1 = DIY 15"
Sub2 = DIY 18"
MBM = MBM ;)

Sub1 is very close to the mains. I haven't done any exact measurements but it might be 20-30cm further away than the mains. So I should set delay on my receiver to 1ft ?

I gotta admit this is a bit confusing.. but if I got this right, I should set the delay on my MBM to: 16.4ft (5m) - 1ft (30.48cm) - 1ft (Delay from routing) = 14.4ft.

Sub2 should be set to: 16.4ft (5m) - 3ft (91.5cm) -1ft = 12.4ft

Sub1 should stay as it is ?

[mojave]

Your delay for the subs/MBM should be set according to their difference between the mains and the listening position and the subs and the listening position (probably the center of your 3man couch). You don't provide these distances in your nice drawing.

I'm going to assume that the listening position (measured from you ear to front speaker) is 15 ft from the mains. Sub1 is 15 ft from the listening position, Sub 2 is 5 ft from the listening position, and the MBM is 3 ft from the listening position. I measure from my ear location to the center of the sub's driver to get its distance. Try to use accurate measurement and don't round. The DCX2496 can handle precision.

Since Sub1 already gets a 1ft delay by routing through the DCX2496 it should not need a delay.

Sub2 - If it is 5 ft from the listening position it needs to be delayed by 9ft. 15 ft - 5 ft - 1ft = 9 ft

MBM - If it is 3 ft from the listening position it needs to be delayed by 11 ft. (15 ft - 3 ft - 1 ft = 11 ft).

Imagine if all your speakers and subs are in a straight line. You want to delay the sound of some of them so that the sound reaches your ear from all of them at the same time.

[E_M]

Thanks a lot for the help mojave :) I get it now!

I was also going to ask you where to measure from - but you already beat me to it! (I wasn't sure if it was from listening position to subwoofer driver or from listening position to the "port" opening on the subwoofer).

It's getting very late here, so I won't do any measurements before tomorrow.

A little offtopic: After playing with REW/DCX2496 today (It's not an easy task getting a decent FR in my room), a mysterious "pop" has come back. It happends like every 30minutes or something, and it's a very low "pop" coming from one of the subwoofers (it's not an over excursion or anything like that.. not a clack). I had this problem once before, but it just went away on its own. Just thought I could mention it - in case anyone know what is causing this.

[E_M]

Well, today I re-measured and put in the new values for delay on the DCX2496. When listening to music, it felt "right". This was on my "old" receiver though..

I just hooked up my new receiver (Yamaha RX-v1800), and I have mixed "feelings" with this unit (Need to play some more with it). First I tried "Ypao" and it set all my speakers to LARGE etc... not good... so I manually set everything to Small and Xovered at 80hz. The lowest I can set the "Subwoofer distance" to is "0.3m" (1ft).. I also set all my speakers to it's correct "distance" (Ypao measured the distance to 4.5m.. while my own measurements came to 4.2m). Sub1 now gets 2ft delay instead of 1ft.. And now im babbling ! I'll just experiment some more with it I guess!

[mojave]

Remember, the measurements are all relative to each other. If you use the same distance for the mains and Sub1, then there will actually be no delay since they are all the same distance from the listener. You can now add delay to Sub2 and the MBM using the DCX2496. Tell me your exact distances to all speakers/subs/mbm from the listening position and I'll tell you what to use for your settings.

[mojave]

Another thing to note is that subwoofers will sometimes need a smaller distance setting than their actual measurement to blend properly. If you feel that the MBM or Sub2 is localized, or you hear it behind you and to the side, then try reducing the distance setting in small increments. Read more here: Subwoofer Localization (http://forum.hsuresearch.com/showthread.php?t=3855). Also, you may want to add some attenuators to the ends of your cables before they go into the subwoofers/MBM. I purchased some -12 dB attenuators from Phil Bamberg at Bamburg Engineering Sound Labs (BESL) (http://www.bambergaudio.com/dcx2496.shtml). You can also get them at Parts Express (http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=266-244), but they are half the price from BESL.

[andyg]

you may want to add some attenuators to the ends of your cables before they go into the subwoofers/MBM.

Mojave,

What is the purpose of 12db attenuation?

[mojave]

There are two different output voltages that are used for devices and they are typically called "pro" and "consumer" output. The pro is a higher voltage than the consumer level. Most receivers will send out a consumer level on its sub out. The sub's input also expects to receive a consumer level input. When the DCX2496 sends a pro level signal to the sub with its consumer level input there are several problems:

1. There is less control available when using the volume knob on the sub. I could only use the about 1/8th of the volume knob. Just the slightest change would result in several dBs of volume change. Imagine if the volume control on your receiver went from 1-50, but 5 was already as loud as you could handle. You couldn't get the precision necessary from only 1-5 if that covered the entire volume range.

2. You have a reduced signal/noise ratio.

3. You have less dynamic range available.

I was noticing some distortion with my MBM-12 when using the DCX2496 and was trying to figure out why. I came across a few threads (http://www.diyaudio.com/forums/showthread.php?threadid=63547) about the DCX2496 and attenuation. I then found that Phil Bamberg sold the DCX2496 and attenuators so I talked to him and he recommended that I use them.