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MBM's don't have much xmax to start with.
Furthermore ported and horned subs minimize excursion, unlike sealed or IB that maximizes it.
Additionally, mid-bass doesn't typically require a whole lot of excursion to be loud.
Where as 1-20hz requires all-your-xmax-are-belong.

The only thing that will really help is turning your bed channel trims to -10db and the LFE left at 0db, and then cranking the master volume. The loudness isn't a problem unless you are running out of master volume, it's all relativistic.

The reality is that XLR has a much higher average and peak voltage requirement. Therefore you need a sound processor like a 7705 or RMC-1 or whatever, something will real-XLR.

Now if the Crown's have unbalanced inputs and the AVR has unbalanced outputs and it still can't drive it then something is seriously wrong with either the AVR you are using or the Crown's are defective.

Perhaps the EQ in your AVR or minidsp or crown is doing something stupid to the signal strength. This is why I always run in direct-mode whenever possible, especially when troubleshooting.

One thing I like about the FP amps is that they have a wide range of adjustibility. Like 12db on the backpanel, and more on the front panel. They also have nice LED trees to see how stressed the amp is, clear even when viewed from 30ft away.
 

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I’m not expecting it to clip
With all the drivers disconnected you should be able to clip the crown without clipping the AVR.
If you can't then you'll never get the full clean power from the crown. (Which may or may not be a problem.)

You'll be able to tell if the Crown is clipping, the AVR will be much more difficult as they don't have indications of that (you can thank the consumer sheeple/eaters for accepting inadequacy as something acceptable. :p)
You'll need an o-scope or a voltage-divider and analog soundcard input + REW.
SMD also has some audio testing gear, no idea how good/bad it is.

Even 3db below clipping is still only 50% power so you really do have to be able to clip it

and on that note: it makes one wonder if you really need every-last-db that your gear has.
That's usually a sign that you need twice as many subwoofers and amps if you are pushing it to near the limits like that.
Amps and drivers don't like to be played at max-excursion and max output-power dude.
Bad things happen. Magic-smoke coming from the amps and coils etc.
(You last-db'ers know who you are!!! :D)

In a "perfect universe" your amps and drivers would be closer to ~25% output (-6db) below clipping/bottoming when you are
tapping-out from ear-pain. i.e. overkill headroom i.e. MOAR ;) :D :p
 

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Discussion Starter #23
MBM's don't have much xmax to start with.
Furthermore ported and horned subs minimize excursion, unlike sealed or IB that maximizes it.
Additionally, mid-bass doesn't typically require a whole lot of excursion to be loud.
Where as 1-20hz requires all-your-xmax-are-belong.

The only thing that will really help is turning your bed channel trims to -10db and the LFE left at 0db, and then cranking the master volume. The loudness isn't a problem unless you are running out of master volume, it's all relativistic.

The reality is that XLR has a much higher average and peak voltage requirement. Therefore you need a sound processor like a 7705 or RMC-1 or whatever, something will real-XLR.

Now if the Crown's have unbalanced inputs and the AVR has unbalanced outputs and it still can't drive it then something is seriously wrong with either the AVR you are using or the Crown's are defective.

Perhaps the EQ in your AVR or minidsp or crown is doing something stupid to the signal strength. This is why I always run in direct-mode whenever possible, especially when troubleshooting.

One thing I like about the FP amps is that they have a wide range of adjustibility. Like 12db on the backpanel, and more on the front panel. They also have nice LED trees to see how stressed the amp is, clear even when viewed from 30ft away.
When you see the results you'll realize something is deeply wrong. I can get more bass out of my 6" center channel at 60W.
 

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Where you at TJ? I think I've asked before but your profile doesnt say anything to give me an idea of if your close enough for one of us to swing by and check things out...
 

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If you can monitor the output level in the MiniDSP, see how high it is. If you're nowhere near clipping it, add some gain in the DSP.

Also keep in mind that a Cleanbox Pro provides a max of 21 dB gain, unbalanced to balanced. That's pretty significant. If it solves your issues I wouldn't feel bad about using it.
 

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Discussion Starter #26
Where you at TJ? I think I've asked before but your profile doesnt say anything to give me an idea of if your close enough for one of us to swing by and check things out...
Wow! That's a gracious thought! I'm in Madison Wisconsin.
 

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Discussion Starter #27
If you can monitor the output level in the MiniDSP, see how high it is. If you're nowhere near clipping it, add some gain in the DSP.

Also keep in mind that a Cleanbox Pro provides a max of 21 dB gain, unbalanced to balanced. That's pretty significant. If it solves your issues I wouldn't feel bad about using it.
Holy cats 21dB. I heard it was 4 or 6. That's insane.
 

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Wow! That's a gracious thought! I'm in Madison Wisconsin.

As a fellow Midwesterner I try it be as friendly as possible. That said your 5 1/2 hours from me one way lol. That’s a *bit* outside where I can go on a day trip lol.

That said I know there are guys in Chicago that might be up for a trip, or who you might be able to visit with gear in hand to troubleshoot...

Assuming you find one if em, Chicago’s got some good places to visit.... maybe let the wife shop after dropping you off, and send the kids to grandmas for the day lol....

Hopefully though your pictures tell us enough to get you sorted.


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When you see the results you'll realize something is deeply wrong. I can get more bass out of my 6" center channel at 60W.
Your gain structure must be horribly out of wack for a Crown 2k to be out-done by any AVR, ever made...

Or your sub is out of phase with everything else, or you're sitting in a room-null that is acting like a black-hole the size of antarctica.

You plug the RCA into the cleanbox and the XLR cable from the cleanbox to the crown, and it "should" in-theory be able to clip that amp with ease (and that power should either smoke the sub or push it to Mars and back.)

I've never owned a XLS 2k or a miniDSP or a 12" MBM so I can't help you debug this remotely. Your equipment is too vastly different than mine. I can only give you generic guidance. My cleanboxes are connected between the Oppo and Motu's, which are then connected to my amps, which are FP's. Apples and Oranges...
 

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Are the gain knobs on the crown turned up all the way? I need to run my inukes gain all the way up to work properly.
 

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Discussion Starter #31 (Edited)
Are the gain knobs on the crown turned up all the way? I need to run my inukes gain all the way up to work properly.
Yes and they still are insufficient without the cleanbox. I'll be posting some measurements when I get a chance but I have 2 young kids and work during the week so my free time is when they are in bed and running REW sweeps when they are sleeping is a no-go. Plus, we have family in town this weekend. Hopefully, by some miracle, I'll be able to get some time in to get this done next week...

I don't even have Dirac running and I'm just running no room correction and have been for months (in fairness, I was waiting for my wall treatments and MBM's to be completed). After I get this gain "issue" under control, I can use the MiniDSP to blend the subs with a digital crossover, time align them, and flatten them. Unfortunately, I don't think MSO will work because I have 2 sets of subs that don't use the same frequency spectrum.

Also, I have a Rotel 976 coming in the mail tomorrow for my Rears and tops and then have to send the NAD in for repair... It's coming to a close. So I'll send the NAD in for repair, re-cable EVERYTHING, get the NAD back, evaluate the subs, gain match/time-align/flatten, run Dirac. Wait a few years and get a 77" OLED and maybe DIY some 18" ULF speakers to replace the Rythmiks.
 

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Can you upload screenshots of the MiniDSP settings? You dont need to measure anything to do this, just open the MiniDSP program and take shots of the different screens so we can follow the signal path for each of the 4 outputs.

This is where I'd want to look at things too, and it can be done without pulling out anything but your computer. As a father of two I'd start there as its the easiest to do at any time :).
 

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Man, do I ever understand the "quiet house" problem. Once I build my insulated barn door, I might be able to run sweeps and measurements at home, but that is not happening yet lol.

Without all the info, I'm not 100% sure why you need both the Rythmik and MBM's on LFE duty. Unless the Rythmic subs have horrible response in their location, using them for a 20hz window seems like a waste since they show to be responsive all the way up to 200 hz. Of course, this is a different subject than having to max out gain knobs on the Crown, but might come in to play regarding overall in-room performance. This doesn't even take into account that you have very nice mains that should (depending on room response, etc) also be able to help with a summing room response in the crossover region. Keep us posted when you can show some more of the gain structure information. If you are in contact with NAD anyways, it would be a great opportunity to ask them directly what their unbalanced pre-out voltage numbers are.

I'm no multi-sub wizard, but you might see about having a conversation with one of the guys that is. I'm willing to bet you have substantial gains to be made with the equipment you already have. If you have a small area for your MLP, posting graphs of the sweeps from each individual component will give some of these room response geniuses a way to get you pointed the right direction.
 

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Discussion Starter #34
Man, do I ever understand the "quiet house" problem. Once I build my insulated barn door, I might be able to run sweeps and measurements at home, but that is not happening yet lol.

Without all the info, I'm not 100% sure why you need both the Rythmik and MBM's on LFE duty. Unless the Rythmic subs have horrible response in their location, using them for a 20hz window seems like a waste since they show to be responsive all the way up to 200 hz. Of course, this is a different subject than having to max out gain knobs on the Crown, but might come in to play regarding overall in-room performance. This doesn't even take into account that you have very nice mains that should (depending on room response, etc) also be able to help with a summing room response in the crossover region. Keep us posted when you can show some more of the gain structure information. If you are in contact with NAD anyways, it would be a great opportunity to ask them directly what their unbalanced pre-out voltage numbers are.

I'm no multi-sub wizard, but you might see about having a conversation with one of the guys that is. I'm willing to bet you have substantial gains to be made with the equipment you already have. If you have a small area for your MLP, posting graphs of the sweeps from each individual component will give some of these room response geniuses a way to get you pointed the right direction.
I have staggered studs, denim, double 3/4 drywall and green glue but something about the sweeps really bothers my wife.

Given that the MBM's can't really go below 35Hz, I need the Rythmiks to pick up the slack there. I suppose I could have the Rythmiks run 20 to 120 and supplement the midbass with the MBM's.

The room placement of the MBM's does not play a factor with this issue. They are laughably quiet. Like not even noticeable from 18" away.

QUESTION: wouldn't the voltage coming out of the NAD not matter because it's hitting a MiniDSP which is being used as a splitter? Wouldn't the output voltage be set by that? And if my Rythmiks were getting enough voltage on a 30' run and I switched the outputs to the crown at a 2' run, wouldn't it stand to reason that the voltage coming out of the miniDSP is not the issue?
I get all of this is speculative until measurements happen but given my inability to take them for a bit, I'm evaluating the logic.
These measurements can't come soon enough!
 

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I believe I had to bridge my XLS 1002 to get adequate output from my magnum-12s. my source (computer soundcard) was 3dB below other sources I tested with, +3 on my AVR to compensate.

Context: 99% music, replaygain enabled, AVR sometimes goes to -10dB, but able to stay at 0dB with the lights going without clipping. 24Hz tuning, Fusion-6 fronts. I keep the crown 3 ticks from full for casual listening, full when for fun.

edit: AVR's preout is 2V, can use either input voltage but .775 had a slight increase in volume.
 

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I'm running a 3000DSP to my two MBM's and its barely panting, I HAD to increase the voltage or run my sub out's really hot in order to get my amp to work right. I'm not sure if the MiniDSP is unable to feed your amp correctly or not but seeing as with the Cleanbox you are good on output and without you aren't that's a pretty clear indication the MiniDSP isn't feeding your amp well enough.


When I bridged my 3000DSP and ran both off the single channel in 4ohm mode they nearly broke me, the Mag12's are super loud.
 

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Discussion Starter #37
I'm running a 3000DSP to my two MBM's and its barely panting, I HAD to increase the voltage or run my sub out's really hot in order to get my amp to work right. I'm not sure if the MiniDSP is unable to feed your amp correctly or not but seeing as with the Cleanbox you are good on output and without you aren't that's a pretty clear indication the MiniDSP isn't feeding your amp well enough.


When I bridged my 3000DSP and ran both off the single channel in 4ohm mode they nearly broke me, the Mag12's are super loud.
The iNukes don’t offer a .775 option do they? Also, even if I bypass the miniDSP the amps aren’t fed. So both the AVR and the miniDSP can’t give the crown enough voltage even with the crown at .775 setting
 

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The iNukes don’t offer a .775 option do they? Also, even if I bypass the miniDSP the amps aren’t fed. So both the AVR and the miniDSP can’t give the crown enough voltage even with the crown at .775 setting

Why don't you just measure your sub output voltage from your receiver? You have a multimeter?
 

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Discussion Starter #39
The iNukes don’t offer a .775 option do they? Also, even if I bypass the miniDSP the amps aren’t fed. So both the AVR and the miniDSP can’t give the crown enough voltage even with the crown at .775 setting

Why don't you just measure your sub output voltage from your receiver? You have a multimeter?
I do have a mutlimeter
 

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The iNukes don’t offer a .775 option do they? Also, even if I bypass the miniDSP the amps aren’t fed. So both the AVR and the miniDSP can’t give the crown enough voltage even with the crown at .775 setting


Oh I wish they did, but sadly they don’t. To be honest I’m surprised you need the cleanbox for the crown though.


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