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Problem integrating Pro audio with home gear.

6K views 49 replies 5 participants last post by  Rudy81 
#1 ·
I am having problems trying to integrate home audio system with pro gear. I am trying to use an EV DC-ONE to actively filter my Klipschorns. Here is the situation.


Goal: Be able to actively cross my Khorns with an EV DC-ONE.


Setup: Integra DHC 9.9 pre/pro source ( balanced), to EV DC-ONE (balanced), to Parasound HALO A23 and A52 amps (balanced), to Khorn drivers. Two in six out setup.



Problem: It all works, but I get loud hissing from the mid and tweeters when the system powers on and can be heard anywhere in the room without music playing.


The system is very quiet when amps are on and nothing else if I take the EV out. When I turn on the EV, the hissing starts. If I mute the EV channels, the hiss is still there. I have guessed this is a gain matching problem. The A23 has gain knobs and when I lower the gain a little on the amps, the hiss goes away. Problem is the A52 doesn't have gain knobs.


So, I decided to try going XLR to RCA on the EV output so I can use a Parasound HCA-1205 5 channel amp that has gain knobs, but no XLR inputs. I got the cables, but they are picking up some wicked RFI. These XLR to RCA cables have pins 1,3 and the XLR case hooked together going to the RCA shield. Pin 2 is going to the center RCA pin.


Bottom line is I'm between a rock and a hard place. If I go all balanced, I get noise floor hissing. If I go XLR to RCA, I get terrible RFI.


Any ideas on how to solve this?
 
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#2 ·
Ignoring the hissing for the time being: With the loudest volume level you would ever listen at, where is the Integra’s volume control set? For instance, with 100% being all the way up, is the Integra set at 25% at your maximum listening level, 40%, or what?


Regards,

Wayne A. Pflughaupt
 
#3 ·

Quote:
Originally Posted by Wayne A. Pflughaupt /forum/post/17956817

Ignoring the hissing for the time being: With the loudest volume level you would ever listen at, where is the Integra's volume control set? For instance, with 100% being all the way up, is the Integra set at 25% at your maximum listening level, 40%, or what?


Regards,

Wayne A. Pflughaupt

Wayne: The Integra sets the volume for 75dB at "0". on the digital volume display. I can go to the 0 point no problem. It does not matter what the volume level or muting is set at, the hiss is always there.
 
#5 ·
Wayne, sorry I didn't answer the actual question. The loudest I listen to is about 65% of the maximum the Integra volume control will go. I rarely listen that loud though.
 
#6 ·
Hmm - not the answer I expected, but I’ll go with my gut feeling anyway.


Let’s start with your speakers. The Klipshorns are extremely efficient. Even with their stock passive crossovers, they have a 105 dB efficiency rating. Keep in mind that passive crossovers rob power; eliminating the passive crossover and going fully active like you’re doing, I can’t imagine what the Klipschorn’s efficiency would become – maybe 110 dB or even higher.


All that means, it doesn’t take a lot of power to make these speakers “go.” They can probably do with 10 watts what other speakers would need 80-100 for.


Next the electronics. As you may know, pro gear and home gear is designed to operate at different signal levels. The nominal operating level of pro gear is +4 dBu, while a -10 dBV signal level is the norm for home audio gear.


Looking at the Integra and Parasound specs, they “read” like typical home audio equipment specs, not like pro audio specs. Based on that, I’m going to hazard an educated guess that even though they accept and output balanced signals, they are nevertheless low-level -10 dBV “home audio” signals.


Basically, I think your issue is poor gain settings in the EV crossover, coupled with the highly efficient Klipsch speakers. More specifically, I expect that the EV’s gains are set too high.


I can’t find a manual for the DC-ONE, but if it’s like a typical analog crossover, it will have for each channel a master level control, as well as individual level controls for high, mid, low etc. outputs. A common scenario that would generate hiss would be if say, the master was full open while the filtered outputs were very low. Or vice versa. Pro audio gear in general tends to be somewhat noisier than home audio gear, because of the higher nominal operating range. So running any gains full-up in a pro processor is only going to aggravate the problem.


I suggest trying the follow gain-matching exercise. You’ll need an SPL meter and a pink noise signal source.


Hook up one of your midrange drivers as such:

Integra -> Parasound A52 Amp -> midrange speaker.


Hook up the other midrange driver as such:

Integra -> EV -> Parasound A52 Amp -> midrange speaker.


(You’ll note for this that I’m recommending using the amp that doesn’t have gain controls.)


The speaker w/o the EV in the signal chain, keep in mind that you’re sending a full-range signal to a midrange driver, so be very carefull!


We’ll begin with the channel w/o the EV. Pan the Integra’s balance control over to that channel, start the pink noise, and bring the Integra’s volume up to the point where the sound from the speaker measures something in the 70-75 dB-SPL range, or whatever you feel is a safe level for the driver.


Now, the channel with the EV in the signal chain. Switch the Integra’s balance control over this channel, but don’t change the Integra’s volume setting. Go through the EV’s menus and make sure all equalizer filters are turned off, or at least set for zero gain. Also, turn off all compression and limiters, and any other processing as well.


Start with the EV’s gain controls very low, and slowly bring them up (both master and midrange) until the SPL level matches what you had with the other channel.


This should level-match the EV to the rest of the system, and you should now be able to interchange the A52 with the A23, with the latter’s gains all the way up. Hopefully you also now have a quiet system. You might try tweaking the EV’s master vs. midrange gains to see if having one higher than the other gets quieter results. Once you’re happy with your settings, go into the EV menu and duplicate the midrange gain settings for the high (tweeter) and low (woofer) outputs.


I expect that the Klipschorn’s compression horns (mids and highs) will be more efficient than the woofer, which means that with low/mid/high signal levels matched, the mids and highs will be louder. If this is the case, don’t increase the EV’s woofer level, but decrease the mid and high level.


If you’re using EQ, you may have to re-adjust your levels after equalizing.


If none of this helps with the noise problems, then I suspect that the EV is simply not compatible with a home audio system.


Regards,

Wayne A. Pflughaupt
 
#7 ·
Wayne, thank you. I will tinker with this when I have a chance. For the time being, I have gotten so frustrated working on it for the last month and not getting past the setup stage that I have given up for the time being.


BTW, the DC-ONE manual can be downloaded from here: http://www.electro-voice.com/downloads.php


Do you think that if I went with a pro amp that I woud be able to control the problem using the amp gain? Or is that no better?


Thank you again.
 
#8 ·
Wayne: In re-reading your post, I realized that either I'm not familiar enough with the DC1, or it does not have input gain control. It does have a -6dB input attenuation button on the back, but that is it. There is no way to attenuate the incoming signal. All I have found is the gain for each output channel. If I bring the gains of the 6 output channels all the way down, the hiss is still there, at the same 'volume'. I can even mute the EV and it still has the hiss.


Edit: I wanted to add the following observation. The DC1 has input and output level LCDs on the front. Depending on how I set up the Integra channel attenuation, I can get the input LCD's to light up to +3 when playing very loud. However, no matter what I do, I can never get the output LCD's off the floor. I'm sure this is all part of the gain issue. I need to learn about gain matching equiment etc.
 
#9 ·

Quote:
Wayne: In re-reading your post, I realized that either I'm not familiar enough with the DC1, or it does not have input gain control.
Yeah, the manual says it does not have one.
Quote:
Do you think that if I went with a pro amp that I woud be able to control the problem using the amp gain? Or is that no better?
Hard to say at this point. You'd need a pro amp with a sensitivity rating comparable to the Parasounds anyway, so I'm thinking it would be no better.
Quote:
It does have a -6dB input attenuation button on the back, but that is it. There is no way to attenuate the incoming signal.
The input signal doesn't need to be attenuated, it's low enough already. Maybe too low .



What about any on-board equalization, compression etc.? Is all that stuff disabled?


Does the noise level change when you change the Integra's volume setting?


If you disconnect the Integra from the signal chain, do you still get noise just with the EV and Parasound amps?



Regards,

Wayne A. Pflughaupt
 
#10 ·
I'm beginning to understand your comment about the input signal being too low. As best I can tell, I have disabled everything, the PEQ, GEQ, etc. The noise level is constant no matter what I do. If I mute the Integra, same noise level. If I remove the Integra from the chain, same noise level. What I have found is the following.


Amps only to speakers. No noise, unless I stick my head inside a horn.


Amps and EV only, noise comes on as soon as EV finishes booting. Nothing I do on the EV control makes the hiss level decrease or increase. Same noise, regardless of controls or muting or anything else.


The only way I was ever able to lower the hiss level was to connect the EV to the A23, which has gain attenuation. I can reduce the gain know about 1/4 and get the his so it is not audible at the listening position. This is why I was considering pro amps that do have gain attenuation and balanced connections.
 
#11 ·
Looking through the manual I don’t seem to be able to find an EQ bypass function. If there is not one, you should go through each filter setting to make sure they are all zero’d. This would be necessary for both the parametric and graphic equalization. I notice that this unit has both input and output equalization, so check out both of them.


Also, make sure you aren’t using any of the factory presets, as they may be designed for specific PA systems and most likely include equalization, limiting, etc.


Regards,

Wayne A. Pflughaupt
 
#12 ·
Wayne: Thank you for looking into this. The owners manual is rather sketchy on what the unit can really do. The pc based software is really nice and provides many abilities not listed in the manual. The PEQ and GEQ all have their won interface and have a master button to enable or disable those functions.


My setup began from scratch, no presets. I am 99.9% sure that the issue is simply a gain problem created by super efficient speakers and mixing home and pro audio. For the time being, I'm taking a break from working on this but plan to visit the issue later. For the time being I'm going to start looking at pro amps that I could use for the project. I know next to nothing about pro amps, so need to research an amp that doesn't cost an arm and a leg and has reasonably good sound character. I know many guys who use Klipschorns and Jubilees use the Crown XTi and similar amps.
 
#13 ·

Quote:
For the time being I'm going to start looking at pro amps that I could use for the project.
Well, that seems like an extreme waste. Keep in mind that the signal from a home audio pre amp is about as low a signal as a pro amplifier can ever expect to receive, and as such it’s going to require the amp’s gains to be set near max. Reducing the gains from there can only mean that the amp will never be driven to its maximum power output. Sure, the power remaining might be sufficient to drive your speakers, but it’s a real waste to have an amp capable of 200, 400 watts or whatever, if you’re only going to use 50 watts.


Personally, I’m leaning towards the conclusion that either your particular DC-One is defective, or the product as a whole is problematic and unsuitable for use in a home theater.


For instance, something caught my eye in the owner’s manual that I found unsettling. Page 20 says, “Optimal signal-to-noise performance is obtained when the nominal (average), input level consistently lights the +3dBu (green) and / or +6dBu (yellow) LED indicators.” Looking at the picture of the DC-One’s input meters shows that these are the maximum-level LED elements before clipping. Maxing out the signal levels like that is contrary to accepted pro-audio gain structure protocol, which typically recommends 12-20 dB headroom.


I’ve been doing research for several months on the topic of gain structure and level setting when trying to integrate home and pro gear into a cohesive system, and have pored over numerous manuals of digital equalizers and speaker processors like the DC-One. It’s interesting to note that, by and far, you never see any mention of level-setting in the manuals of these products. This is because the 24-bit A/D converters commonly used these days should be capable of over 140 dB dynamic range. Real world realities (such as power supplies and other circuitry in the components) typically limits bottom-line noise specs to at best 115 dB, but the capabilities of 24-bit converters should mean that you have at least 30-40 dB “slop factor” before inadequate signal levels will begin to have an effect on background noise levels.


I have found one exception to “no mention of input signal levels,” however: The low-end Behringer DSP1124 Feedback Destroyer that is popular in home theater circles as a subwoofer equalizer. The DSP1124 manual also recommends keeping signal levels high, but even so it doesn’t go so far as to say “they should be kept just below clipping at all times,” as the DC-One recommends.


Big deal, you say? Well, I’ve connected the DSP1124 to my HT system, and guess what? It’s a noise machine, just like you’re describing with the DC-One, despite its 24-bit Sigma Delta converters (which by the way is the same kind the DC-One has). And I wasn’t even using ultra-high-efficiency speakers like your Klipsch. With more ordinary speakers, I could easily hear the noise a couple of feet away. I imagine it would have been considerably worse with highly efficient speakers like the Klipschorns. The BFD does have one benefit the DC-One doesn’t, -10 dBV / +4 dBu switchable operating ranges. Switching to the consumer -10 dBu range lowers noise considerably, but even then it’s far noisier than any other digital or analog EQ I’ve tried in my home system. Obviously, the BFD has some problems with its overall design and circuitry. It looks to me like the DC-One does too, or at least your particular unit.


The other thing that gives me pause about the DC-One is all the RF noise you said you got when trying to use it unbalanced with some RCA-XLR cables. It’s virtually impossible to get that kind of interference from a properly shielded unbalanced cable, especially if they’re as short as what you’re using. An easy way to double check if your cables are okay, unplug them from DC-One and connect the XLR ends together. If the RFI goes away, then you’ve isolated the problem to the DC-One.


Before springing for a rack full of new pro amps, I’d suggest trying some different speaker processors. I’m sure you probably cringe at the thought, but I know people who are using the lowly Behringer DCX-2496 with no complaints of noise. If that doesn’t float your boat, try another one where the manual doesn’t recommend maxing out signal levels. Based on both your EV unit and the BFD, "max out the input levels" advice seems to be an indicator of a potentially noisy unit.


Regards,

Wayne A. Pflughaupt
 
#14 ·
Wayne: I can't thank you enough for your research and for taking the time to help educate me. You make a lot of sense. I am cancelling my search for different amplifiers and will focus instead on a different DSP that can coexist better with home gear.


Excellent discussion on the reasons and science behind the gain thing. It has been a tough concept to grasp. Seems it should just plug in and work.


Thanks again,

Rudy
 
#17 ·

Quote:
Originally Posted by Rudy81 /forum/post/17983360


Wayne: I thought I would try the Behringer DCX-2496. Any problems you would anticipate with that unit?

Shouldn't be with pro gear and levels. I own three and they link up well with the big rack of pro amps I own and use.


However, some domestic gear will not provide enough level to the ADCs to reach 0dBFS.
 
#18 ·
I just caught your thread and I find it very interesting. (You're getting some great advice in this unfortunate glitch you are having.) I would have to agree that looking for new amps is going to be a waste of time and money (unless you're looking for serious power and db's). Now on the noise front I have an extremely powerful pro sound setup (10 pro amps) with home audio amps integrated as well (2) and there is no audible hiss at normal listening levels (70-115db's+). It sure sounds like the unit you are trying to integrate is of a quality that does not conform to your particular application. As far as home audio and pro audio are concerned they do blend and interact quite well together. I'll be checking this thread more closely and hope you find a solution. If I can think of something usefull I'll let you know.
 
#19 ·

Quote:
Originally Posted by A9X-308 /forum/post/17985382


Shouldn't be with pro gear and levels. I own three and they link up well with the big rack of pro amps I own and use.


However, some domestic gear will not provide enough level to the ADCs to reach 0dBFS.

That's my problem. I am using an Integra DHC 9.9 as the source and it is a consumer product, so probably provides a very low signal.
 
#20 ·

Quote:
Originally Posted by W.S. /forum/post/17985852


I just caught your thread and I find it very interesting. (You're getting some great advice in this unfortunate glitch you are having.) I would have to agree that looking for new amps is going to be a waste of time and money (unless you're looking for serious power and db's). Now on the noise front I have an extremely powerful pro sound setup (10 pro amps) with home audio amps integrated as well (2) and there is no audible hiss at normal listening levels (70-115db's+). It sure sounds like the unit you are trying to integrate is of a quality that does not conform to your particular application. As far as home audio and pro audio are concerned they do blend and interact quite well together. I'll be checking this thread more closely and hope you find a solution. If I can think of something usefull I'll let you know.

Thank you. This project all started as an experiment to actively filter my Klipschorns. I originally selected the EV DC-One due to its two in/three out setup. However, that unit, the mix with consumer gear, and the very high efficiency of the Khorns are a problem. The excellent advise here has steered me away from getting different amps just for this purpose, although I am looking for some Crown D-75's to power my tweeters and mid range JBL 2470's. I'm still trying to figure out if they have enough power for that application.


I may try the Behringer since it has input and output gain that is variable +/- 15dB.


This has been a lot of fun, at time frustrating, but certainly educational. I am pretty convinced after my first listening to the effect of going active, that it is the way to go. I have some very good passive crossovers, but the flexibility of the active system is very inviting.
 
#21 ·
I have forgotten to ask. Is there a commercially available 'box' that will convert my consumer audio -10dBV to +4dBu? I think making this conversion might solve a lot of dynamic range problems.
 
#22 ·

Quote:
Originally Posted by Rudy81 /forum/post/17987385


That's my problem. I am using an Integra DHC 9.9 as the source and it is a consumer product, so probably provides a very low signal.

Then you need something like this to get the levels up.

Quote:
Originally Posted by Rudy81 /forum/post/17987418


Thank you. This project all started as an experiment to actively filter my Klipschorns. I originally selected the EV DC-One due to its two in/three out setup. However, that unit, the mix with consumer gear, and the very high efficiency of the Khorns are a problem. The excellent advise here has steered me away from getting different amps just for this purpose, although I am looking for some Crown D-75's to power my tweeters and mid range JBL 2470's. I'm still trying to figure out if they have enough power for that application.

I ran active Khorns for ages, eventually modifying them to eliminate all their faults until no part of them was in use any more. Any audible noise in a hi eff system is far more often than not due to the gain structure, than faulty amps. Mine was dead silent.
 
#23 ·
A9X-308: Thanks for the link. I think that is exactly what I need to bump the line level signal to what the crossover needs. After weeks of working on this, it is definately coming down to a gain level issue.


When you had your Khorns, what crossover did you use and how did you handle the gain issue?
 
#24 ·

Quote:
Originally Posted by Rudy81 /forum/post/17988033


When you had your Khorns, what crossover did you use and how did you handle the gain issue?

Originally I built my own analogue unit, then used a pro digital model similar to the DCX, then two as it evolved past a 3 way. Later I moved and almost all of it was sold.


Levels were not an issue for me as I'm an EE and just measured and adjusted until I had it the way I wanted. There is a near 10dB difference in sensitivities of the two power amps I'm using in the current build for MF/HF and LF, but 4 resistors, 20c, solves it. I'm usually not sure what to suggest to other people, as individual products off the shelf are not what I use. The Samson I mentioned as I have seen it used by several here with reportedly good results.


You mention using a 2470 on your K's. What flare are they connected to?
 
#25 ·
A9X-308: The JBL 2470's are mounted on the ALK Trachorns. Found here: http://www.alkeng.com/trachorn.html


I am also using the Eminence APT-150 tweeter.


In your opinion. Can I use the Samson product to get the inputs matched to the pro crossover, then go from the crossover to consumer level amps? The amps, of course will be expecting -10dBV input, not +4dBu. Any potential issues there?
 
#26 ·

Quote:
Originally Posted by Rudy81 /forum/post/17988199


A9X-308: The JBL 2470's are mounted on the ALK Trachorns. Found here: http://www.alkeng.com/trachorn.html

Not heard the ALK but it's got to be better than the K400, which is the worst flare I have ever used.

I ended up with custom made round trax's similar to the Edgars using BMS4590.
Quote:
Originally Posted by Rudy81 /forum/post/17988199


In your opinion. Can I use the Samson product to get the inputs matched to the pro crossover, then go from the crossover to consumer level amps? The amps, of course will be expecting -10dBV input, not +4dBu. Any potential issues there?

It looks like it will do the job well to get the levels up to the ADC, but out of the DCX you will have too much level for consumer amps. This is part of the issue in my build I mention earlier; my MF/HF amp is a domestic unit, but the 15's are driver by a pro amp.


If you can solder leads and small components you could engineer a solution cheaply and simply, but I don't know what to suggest otherwise, and I don't use to DCX digital attenuation to know if that might have some issues or not.
 
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