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macaroonie
10-07-2010, 06:12 PM
Does this unit do what it says on the tin ? :dont-know:

JBL 4645
10-08-2010, 12:31 AM
Does this unit do what it says on the tin ? :dont-know:

Can you, be more specific about “on the tin”?

http://www.dbxpro.com/images/product_pgs/product_images/PA+_front.jpg
http://www.dbxpro.com/images/product_pgs/product_images/PA+_rear.jpg
http://www.dbxpro.com/PA+/

Well if this, unit doesn’t do what you require from it, you could always buy “magic lamp” just rub it a few times and you’re crossovers and EQ is sorted!:D I don’t think you’ll be disappointed with it, ;) besides the sheer cost!:eek::D

You can throw away those primate dinosaur passive crossovers and use the electronic active crossover, selection and its wide variety of features to custom tailor you’re JBL till you’re blue in the face.:p

With passive they just sit there idle! With active there more alive up and running and do a whole lot more for experimentation.

richluvsound
10-08-2010, 01:01 AM
Mac,

I have not heard DBX ..... but ,I have heard XTA ... You seen Jungle Book , the snake Sir Hiss ? well they used the XTA for his voice over !

Then again you have joined the PA set now ! traitor !



Rich

macaroonie
10-08-2010, 06:02 AM
Much more challenging old boy :D

Ash , I know what it does thanks the question should have read something like , is this unit up to snuff.

I can get a Driverack PA for £350. Discontinued model

Tim Rinkerman
10-08-2010, 06:47 AM
What comes out doesn't sound like what went in...I'm glad they discontinued it.

Andyoz
10-08-2010, 06:47 AM
Big differences sonically between the Driverack PA and 260 apparently. Save up for the 260...

cooky1257
10-08-2010, 07:45 AM
The dbx will do what it says on the tin but it wont do it as well or as sonically satisfying as the equiv XTA. That said the base level XTA will run you a cool £2500 but wont sound 8x better.

macaroonie
10-08-2010, 09:38 AM
Thanks for the replies fellahs. Thats the kind of info I was looking for. I'm guessing that the digital processing is not as tidy as it could be. It certainly does all the tricks as far as X/O EQ and Feedback supression but if it all comes out all spitty sounding then that is no use at all.
Any farther experiences most welcome thanks.

JBL 4645
10-08-2010, 10:19 AM
Much more challenging old boy :D

Ash , I know what it does thanks the question should have read something like , is this unit up to snuff.

I can get a Driverack PA for £350. Discontinued model

:eek:£350 is that a good price! I thought they where a grand?

What's the snuff? Mac, what you been drinking up there.:D That's tobacco! What you been smoking up there?:p

Two places I’d look around thou I’m sure you know one of them is fleabay, the other Google Shopping product might show a few great price deals. £350 is just an average £100 dearer over a DCX2496 which is average £250 thou some places sale it, for just over £200 new in the box.

dbx 4800 as used in the Empire Leicester Square UK prices average £3 grand plus!
http://www.google.co.uk/products?hl=en&biw=1152&bih=745&q=dbx%204800&um=1&ie=UTF-8&sa=N&tab=wf

Fleabay has them going for £1.5garnd thou they are in the US so P&P might be £100 or so still its heck of saving over the UK price.
http://shop.ebay.co.uk/i.html?_nkw=dbx+4800&_sacat=0&_odkw=cinema+RTA&_osacat=0&_trksid=p3286.c0.m270.l1313

http://cgi.ebay.co.uk/DBX-4800-DriveRack-96kHz-driverack-4800-/290470759329?pt=LH_DefaultDomain_0&hash=item43a1680ba1#ht_3398wt_1057

Anyone got a few grand I can borrow. :p

Some cool pricing for dbx driverack pa on fleabay
http://shop.ebay.co.uk/i.html?_nkw=dbx+driverack+pa&_sacat=0&_odkw=cinema+RTA&_osacat=0&_trksid=p3286.c0.m270.l1313

UK Google product not bad prices thou I'd look for the lowest price! Some are around £300 new in the box.
http://www.google.co.uk/products?q=dbx+driverack+pa&hl=en&aq=0&oq=dbx+drive

millennium-music is doing it for £299.00 can't see on the site, but no doubt free P&P
http://www.millennium-music.co.uk/products/categories/subcategories/dbx%20DriveRack%20PX/brands/detail/key/p/ppp/

Some of the sites on Google product listing look a bit dodgy. Millennium-music site is okay, thou I’d be careful about some sites that look shifty looking. Saw one site selling for£292.82 new, but looks dodgy.

Most other sites are still flogging for near to £1grand.

I looked right though Google product and the lowest price is Millennium-music.com.

£244.01 US post worldwide not really worth it! I bet the P&P would be almost equal to £299.00 or just slightly over, plus it takes a few weeks when it could be a few days in the UK.
http://cgi.ebay.co.uk/DBX-Driverack-PA-PA-Plus-DRIVERACK-SYSTEM-/110594558653?pt=LH_DefaultDomain_0&hash=item19bff30abd

The only difference this has over DCX2496 is the twin 28 band EQ and auto lazy EQ for those who can’t be asked to do it manually. I’d need at least x5 for my set-up, with DCX2496 I’d only need x3 and less the cost! So that’s why I’d need a x4 DEQ2496 31 band EQ to add on to handle the EQ over LCRS LFE.1. Plus the DEQ2496 costs a bit more than DCX2496 and as auto EQ and bit more, so its weighing the pros and cons over these units.

You’d still save a bomb with Behringer over dbx.

If ASDA sold dbx drive rack the'd be going of £200.00 new! :p

cooky1257
10-08-2010, 11:08 AM
Mac, you may be able to pick up a s/h Tannoy TDX2 oop there-which is a rebadged XTA 226(minus the card slot).
I use one on xover/peq duties, it sounds great, transparent and flexible-it certainly isn't 'spitty or untidy..

richluvsound
10-08-2010, 11:20 AM
Mac ,

Talk to Tony Shallon at Opus in cornwall ..... He designed there entire system .... from scratch ...that is the cleanist ANALOG pa I have ever heard .... I may not have heard as much as some ,but I do know what sounds good .....

He's knows a bit .. I think its natural that being here on the JBL forum we tend to over look our own back yard ... MC2 is proof of that .... The Europeans know a bit too !

Why would anyone buy a thrashed 20 year JBL pro power amp when you can pick up something as agile and musical as the MC2 gear for pennies more .

Rich .... the usual disclaimer about opinion and all that mate !

JBL 4645
10-08-2010, 11:32 AM
Mac, you may be able to pick up a s/h Tannoy TDX2 oop there-which is a rebadged XTA 226(minus the card slot).
I use one on xover/peq duties, it sounds great, transparent and flexible-it certainly isn't 'spitty or untidy..

Yeah right, does it look like Mac, has £2grand :p
http://www.soundmastersdirect.co.uk/xta-speaker-management-sys-19-1u-2-inputs-and-6-outputs?source=googleps
http://www.www.xta.uk.com/discontd-dp226.jpg

Nice link to JBL set-up using XTA 226
http://www.4xaudio.com/jblshowphotos.html

http://www.dbxpro.com/images/product_pgs/product_images/4800front.jpg


4 channel input with 8 channel outputs so you can use it for straight forward stereo 2channel use the 8channel outputs or

1Sub bass low
2Bass
3 mid range
4 high range

5Sub bass low
6Bass
7 mid range
8high range

Or LCR input with one channel for LFE.1

1 left low
2 left high
3 centre low
4 centre high
5 right low
6 right high
7 LFE.1
8 left low surround

x2 dbx4800

1 left high surround
2 right low surround
3 right high surround
4 centre back left low
5 centre back left high
6 centre back right low
7 centre back high
8

So there are multiple choices of designing the layout, all depends how many channels you want to custom tailor for independent amplification?

If that doesn't satisfy you, you can always use it as glorified paperweight.:D

cooky1257
10-08-2010, 11:42 AM
Yeah Rich, I heard an Opus club system http://www.opuspocus.co.uk/blog-news-events/truth-about-pa-sound-system-k.htm that was the biggest hifi I've ever heard, equaled only by a Funktion1 dance stack http://www.funktion-one.com/home.htm set up with the meanest subs I've ever come across.

JBL 4645
10-08-2010, 12:09 PM
Yeah Rich, I heard an Opus club system http://www.opuspocus.co.uk/blog-news-events/truth-about-pa-sound-system-k.htm that was the biggest hifi I've ever heard, equaled only by a Funktion1 dance stack set up with the meanest subs I've ever come across.

That was good link on the “K” and makes since about power heaters being on full at 1KW over a sound system that would never be pushing to its fullest, would overheat and shut down.

richluvsound
10-08-2010, 12:22 PM
Cooky,

the Funktion 1 rig I heard, the one and only time, was down here at the above venue , Bryston, Clear Audio, XTA ..... what else do you need ....

I still don't understand why Keith from Matter @ 02 went with Martin . You would think that when you are rated The best club in the world, you would atleast go with the best sound in the UK ... I guess after getting the contract for Fabric the deal was too good to refuse !

uF

boputnam
10-17-2010, 04:05 AM
What comes out doesn't sound like what went in...I'm glad they discontinued it.+1 Actually, stuff comes out that was not sent in... :p


Big differences sonically between the Driverack PA and 260 apparently. Save up for the 260...+1, that is, if you must have a Driverack...


The dbx will do what it says on the tin but it wont do it as well or as sonically satisfying as the equiv XTA. That said the base level XTA will run you a cool £2500 but wont sound 8x better.Make the 10x, and I agree. :)


Thanks for the replies fellahs. Thats the kind of info I was looking for. I'm guessing that the digital processing is not as tidy as it could be..Yup and in the digital realm it's all about the A/D and D/A converters. Cutting costs there is like cheapo head-amps on mixing consoles... :banghead:


Mac, you may be able to pick up a s/h Tannoy TDX2 oop there-which is a rebadged XTA 226 (minus the card slot). I use one on xover/peq duties, it sounds great, transparent and flexible-it certainly isn't 'spitty or untidy..A great plan, if true - news to me.

I've used xta for many, many years. I own 3 of them, and always hand-carry one 448 when on a fly-dates tour. It is the most powerful tool in my arsenal. I nightly am re-building PA systems on-the-fly, quickly, and invariably always get a result vastly improved on the install. Time-alignment, good control over the band passes, and phase, coupled with those powerful PEQ's is a wonderful experience.

Plus, the AudioCore software (free) is incredible. Conversely, I've owned one KT DN9848 for over 5-years and have never, ever been able to get it to handshake with my laptop.

cooky1257
10-17-2010, 09:19 AM
http://www.audiocore.co.uk/tech-support-docs/Fitting%20New%20AES%20to%20DP226.pdf
Though not on that list the Funktion X01 is also a rebadged 226.

Steve71
10-19-2010, 12:56 PM
Not a lot of love for the old PA eh...

Well while I don't have anything to compare it to, I will say I'm very satisfied with mine, for the price I payed - $230 USD (used) with a behringer measurement mike.

My only complaint thus far is that it'll send a whopping massive pop through you drivers if you accidentally turn it off first. I leave mine on 24/7 connected to a UPS just in case the power goes out.

Honestly I have this thing connected to some mighty fine amps and drivers, and it sounds really freaking good. I bet a more expensive processor might give a little better resolution. I'd like to compare it to the deqx one day.

Drivers are: Gauss 1502 HF horns above 7.2Khz, Altec 288 RWB CD on 1003 tar filled horns (300-7Khz) and Altec 515G's in DIY 80hz bass horn.

Some pics of my speakers in their current form.
http://www.audioheritage.org/vbulletin/showthread.php?24800-Which-Altec-compression-drivers-are-these/page2

boputnam
10-26-2010, 05:32 PM
Not a lot of love for the old PA eh...:no: :)


My only complaint thus far is that it'll send a whopping massive pop through you drivers if you accidentally turn it off first. Yeah, that is a really bad idea. Not bragging, but the xta does not do that - and, when it comes back up, it restarts with the latest settings, even if you haven't saved them. Those features have saved me from a few unintended disconnects!


Honestly I have this thing connected to some mighty fine amps and drivers, and it sounds really freaking good. I bet a more expensive processor might give a little better resolution. I'd like to compare it to the deqx one day.Yes, it does. Just realize none of these were intended for HiFi - they are not audiophile quality, but are damned good. All of these give increased control over the system response - control not possible otherwise - which can really improve the matching/mating of system and room. Use can be very gratifying!

jerry_rig
10-26-2010, 06:58 PM
A friend let me borrow a Driverack PA recently to bi-amp my hi-fi setup. I was using it to test in concept my plan to run 2 JBL 2235s active with a low pass cutoff around 80Hz, essentially creating a subwoofer. (I'm running the top section full range since it naturally rolls off around 80Hz.) The concept worked brilliantly. But based partly on threads on this forum, I decided to buy an Ashly XR-1001. To my ear, the analogue Ashly sounded much better than the digital Driverack PA. Note I was only using it for low end pass band duties, but the bass was much deeper and tighter. Frankly, I was shocked. It also sounded more natural. The controls are of course much easier to use to boot. Brought a big smile to my face. :D

Steve71
11-05-2010, 09:08 AM
A friend let me borrow a Driverack PA recently to bi-amp my hi-fi setup. I was using it to test in concept my plan to run 2 JBL 2235s active with a low pass cutoff around 80Hz, essentially creating a subwoofer. (I'm running the top section full range since it naturally rolls off around 80Hz.) The concept worked brilliantly. But based partly on threads on this forum, I decided to buy an Ashly XR-1001. To my ear, the analogue Ashly sounded much better than the digital Driverack PA. Note I was only using it for low end pass band duties, but the bass was much deeper and tighter. Frankly, I was shocked. It also sounded more natural. The controls are of course much easier to use to boot. Brought a big smile to my face. :D

Just a thought, but did you have the gain structure set up correctly when using the dbx? In other words, when listening to music were you lighting up some/most of the input & output LEDS on the unit?

jerry_rig
11-05-2010, 11:09 AM
Just a thought, but did you have the gain structure set up correctly when using the dbx? In other words, when listening to music were you lighting up some/most of the input & output LEDS on the unit?

Please don't take my comments as a bonafide review of the DriveRack. I was simply noting what I perceived as cleaner deep bass from the Ashly. All lights on the dbx indicated very low operating levels. As I recall only the first level was lit up. Note that the crossover is being used to match a pair of 2235s to my other speakers. All are driven from the same pre-amp and the low-end power amp does not have attenuation, so I don't have much flexibility to push (or limit) signal strength at the crossover. It is what it is...

Steve71
11-05-2010, 05:04 PM
Please don't take my comments as a bonafide review of the DriveRack. I was simply noting what I perceived as cleaner deep bass from the Ashly. All lights on the dbx indicated very low operating levels. As I recall only the first level was lit up. Note that the crossover is being used to match a pair of 2235s to my other speakers. All are driven from the same pre-amp and the low-end power amp does not have attenuation, so I don't have much flexibility to push (or limit) signal strength at the crossover. It is what it is...

Yeah, it's impossible to set up correct gain structure on the dbx if your amp doesn't have gain controls. That might account for the poor performance.

Then again I cross to a sub at 80hz so I don't actually listen to <80hz bass through my unit.

boputnam
11-08-2010, 04:36 PM
...it's impossible to set up correct gain structure on the dbx if your amp doesn't have gain controls. Not so.

Each band pass you establish in the crossover has separate gain (output), so you can control each band pass gain relative to one-another.

While using Pink Noise on a system, I make coarse adjustments on band pass gains to get the system output as smooth as possible (and as desired...) before applying any PEQ's (or GEQ's). This often reduces the number of filters needed (and avoids their intrinsic phasing anomalies) for optimal response.

Mike Caldwell
11-09-2010, 05:56 AM
I think the DR PA has internal analog gain adjustment jumpers. I know the DR 260 does. Don't wast your time with "auto EQ".

boputnam
11-09-2010, 09:33 PM
Don't wast your time with "auto EQ".:no_wag:

Unless you're :homer:... lol

macaroonie
11-13-2010, 08:58 AM
Well in the end I could not find enough positives for the driverack PA and quite a few cons. The power up thump is a concern as is the audio quality , so I caved in and went for one of these :

48546

On the go here for all of £75 at that price I don't suppose I can go terribly wrong. Plusses are it has CD compensation and delay as well as the usual L/R filters.
On the minus side it is a little cheezy on build quality so fingers crossed.
My M553 stays firmly on the shelf in my lounge.:)

Thanks everyone for you input.

Steve71
11-18-2010, 02:24 PM
Not so.

Each band pass you establish in the crossover has separate gain (output), so you can control each band pass gain relative to one-another.

Sure you can, but since it's done in the digital domain, it's unless for setting up correct gain structure (unless you already happen to be in the ball park). IE it does nothing to reduce the noise the DRPA adds to the chain.

Steve71
11-18-2010, 02:31 PM
I think the DR PA has internal analog gain adjustment jumpers. I know the DR 260 does. Don't wast your time with "auto EQ".

Well if it does, there is no mention of it in the manual.

And while the auto EQ function is far from perfect, it's not a bad starting point. Of course if you have better measuring equipment, then I'd use it instead.

Mike Caldwell
11-18-2010, 02:54 PM
It would make sense that the 260 has the gain adjustment jumpers since that it is the next step up the DBX ladder.

boputnam
11-19-2010, 10:22 PM
Sure you can, but since it's done in the digital domain, it's unless for setting up correct gain structure (unless you already happen to be in the ball park). IE it does nothing to reduce the noise the DRPA adds to the chain.Obviously it's in the digital domain. And, there is nothing you can do about the unit "noise" - if you're using that unit, you accept it's offerings.

Dood - I don't have the manual in front of me, but memory serves there is +/-12 dB on each band pass, allowing a 24 dB relative gain differential between band passes. That should be plenty? I sincerely doubt few systems are so far "out of the ball park" that this would not be enough. dbx aren't dummies in this. I was merely pointing out that your comment was limited in it's scope - it did not acknowledge there is ample gain accommodation, by band pass, available on-board.


And while the auto EQ function is far from perfect, it's not a bad starting point. Bad starting point, and bad idea. If one is embarking into this arena, you are accepting the responsibility of needing a greater understanding of what is going on, and should learn how to work with the acoustic animal you are facing. Get some proper measurement equipment and knowledge - neither is too expensive nor arduous. You can get a LOT more out of this unit by limiting it's auto-functions. That said, I merely know how to run them - I run into them frequently, but own zero of these.

Steve71
11-20-2010, 08:35 AM
Obviously it's in the digital domain. And, there is nothing you can do about the unit "noise" - if you're using that unit, you accept it's offerings.

Dood - I don't have the manual in front of me, but memory serves there is +/-12 dB on each band pass, allowing a 24 dB relative gain differential between band passes. That should be plenty? I sincerely doubt few systems are so far "out of the ball park" that this would not be enough. dbx aren't dummies in this. I was merely pointing out that your comment was limited in it's scope - it did not acknowledge there is ample gain accommodation, by band pass, available on-board.


jerry_rig said he was using an amp without gain controls, which I assumed to be a consumer amp. If it was a pro amp, then my comments don't apply. However assuming JR was using a consumer amp, we have a potential problem which could well account for the sub par sound quality.

So in the context of JR setup, I'm talking about global gain, not relative gain between individual band passes. The outputs on the dbx (+4dbu) will overdrive the inputs on a consumer amp (-10dbu). To overcome this your only option, sans gain controls on the AMPS, is to use the dbx's digital gain controls. Now you've just reduced your s/n ratio by 14db. Not to mention the reduction in resolution on the d/a conversion. Another option would be to turn down your pre amp 14db, but that isn't going to change the s/n ratio as it's fixed in the case of the dbx. And now you've just messed up the a/d and the d/a conversion.



Bad starting point, and bad idea. If one is embarking into this arena, you are accepting the responsibility of needing a greater understanding of what is going on, and should learn how to work with the acoustic animal you are facing. Get some proper measurement equipment and knowledge - neither is too expensive nor arduous. You can get a LOT more out of this unit by limiting it's auto-functions. That said, I merely know how to run them - I run into them frequently, but own zero of these.

This is just a hobby for me, but I do have an Electrical Engineering Degree so I'm not exactly in the dark here. And I agree the auto eq is no free pass, you still have measure if you want to get the most out of the unit. However you can get good results with the auto eq and a little tweaking. Just don't do a single pink and expect it to be right. Don't forget you can also use the RTA monitor function with a PC as a white noise generator and move the mic around the room to get an idea of what's what.

boputnam
12-05-2010, 07:18 PM
jerry_rig said he was using an amp without gain controls, which I assumed to be a consumer amp. If it was a pro amp, then my comments don't apply. However assuming JR was using a consumer amp, we have a potential problem which could well account for the sub par sound quality.

So in the context of JR setup, I'm talking about global gain, not relative gain between individual band passes. The outputs on the dbx (+4dbu) will overdrive the inputs on a consumer amp (-10dbu). To overcome this your only option, sans gain controls on the AMPS, is to use the dbx's digital gain controls. Now you've just reduced your s/n ratio by 14db. Not to mention the reduction in resolution on the d/a conversion. Another option would be to turn down your pre amp 14db, but that isn't going to change the s/n ratio as it's fixed in the case of the dbx. And now you've just messed up the a/d and the d/a conversion.There is nothing in jerry_rig's post to suggest he was using "consumer" stuff - in fact he stated he was using a pre-amp, and he did not mention any issues of overdriving his amps. He seems plenty savvy, and made a good decision based on his sonic preferences.


This is just a hobby for me, but I do have an Electrical Engineering Degree so I'm not exactly in the dark here. And I agree the auto eq is no free pass, you still have measure if you want to get the most out of the unit. However you can get good results with the auto eq and a little tweaking. Just don't do a single pink and expect it to be right. Don't forget you can also use the RTA monitor function with a PC as a white noise generator and move the mic around the room to get an idea of what's what.Good for you. I have an MS in other stuff, but I haven't hung it on the wall in some time... Anyway, I stand by my experiences with this unit and reiterate what I said: Do not use the auto EQ, especially if you have no means to measure what it is doing and what it has done. Without those tools, you really shouldn't be using this level of gear anyway. If one is going to this level, get the requisite gear to measure what is happening in the acoustic (and time) domains, and how much, and how little, you can do about it. It's fun!


:)

Steve71
12-16-2010, 09:31 AM
There is nothing in jerry_rig's post to suggest he was using "consumer" stuff - in fact he stated he was using a pre-amp, and he did not mention any issues of overdriving his amps. He seems plenty savvy, and made a good decision based on his sonic preferences.

The issue is not over driving the power amp. This quote below from JR tells us all we need to know. IE gain structure was not set up correctly - end of story. Now without more details I can't if that's 100% to blame for the SQ issues JR was experiencing. Maybe it really does sound sub par compared to the other crossover, but until we setup both crossovesr correctly, we'll never know.


All lights on the dbx indicated very low operating levels. As I recall only the first level was lit up. Note that the crossover is being used to match a pair of 2235s to my other speakers. All are driven from the same pre-amp and the low-end power amp does not have attenuation, so I don't have much flexibility to push (or limit) signal strength at the crossover. It is what it is...





Good for you. I have an MS in other stuff, but I haven't hung it on the wall in some time...


No need to be patronizing. I mearly mention my degree since (1) it's very relavent to the subject at hand and (2) unlike you I don't have a career in the industry.

You work in the industry, that's enough for me to know where you're coming from. MS in 'other stuff' isn't relevant to the discussion. :)



Anyway, I stand by my experiences with this unit and reiterate what I said: Do not use the auto EQ, especially if you have no means to measure what it is doing and what it has done.

The auto EQ / RTA should be no better or worse than any other auto eq/rta. It's just a tool and is subject to the limitations of that tool. IE room modes and mic calibration. If there is some inherent fault in the dbx's RTA function, I'm all ears.



Without those tools, you really shouldn't be using this level of gear anyway. If one is going to this level, get the requisite gear to measure what is happening in the acoustic (and time) domains, and how much, and how little, you can do about it. It's fun!

No argument there and obviously there is much more to speaker design than slapping a bunch of drivers together and pushing the RTA button.

In your line of work, getting uniform response for the entire room is important so I'd imagine the RTA to be less than useful. But for the 'audiophile' sitting in the sweet spot I've found it to be very useful as a starting point. As I'm sure you know getting a good result for a single spot is a hell of a lot easier than for a whole room.

I've purchased an emu 0404 and will be getting my mic calibrated soon. So at some point in the future I'll be doing a bunch of measurements to fine tune the setup. I've also purchased a Beginner dcx (for use in a IB sub setup) so might even get the chance to compare the two.

jerry_rig
12-16-2010, 01:41 PM
Again, please do not take my comments as a serious review of the DriveRack PA. Just FYI, my "consumer amp" for bass duty is a Krell KSA 300s (recently refurbished at the Krell factory) and I seriously doubt it -- or an incorrect gain structure -- had anything to do with my experience. The system and front end are extremely revealing and I would certainly be aware of anything amiss, gain-wise.

Look, the DR could well be an excellent unit for many users. And in some ways I wish that I had its flexibility in an analogue x-over. Peace.

Steve71
12-16-2010, 02:32 PM
Again, please do not take my comments as a serious review of the DriveRack PA. Just FYI, my "consumer amp" for bass duty is a Krell KSA 300s (recently refurbished at the Krell factory) and I seriously doubt it -- or an incorrect gain structure -- had anything to do with my experience. The system and front end are extremely revealing and I would certainly be aware of anything amiss, gain-wise.

Look, the DR could well be an excellent unit for many users. And in some ways I wish that I had its flexibility in an analogue x-over. Peace.

Hey JR, thanks for chiming in with a bit of more info. :)

As for doubting the gain structure wasn't contributing to the degradation in sound quality... well all I can say is that the lights on the front of the dbx DR PA range from -30 to +20dbu. If you were only hitting the -30dbu light on peaks, then there was (potentially) 50db of signal range you weren't using.

So even if we were to ignore the potential degradation of quantization in the D/A process, you've just reduced the drive racks s/n ratio by 50db! That is significant especially since the the DR only has a s/n ratio of 95db to begin with.

In other words the DRPA you tested had a S/N ratio of 45db due to the way it was setup. I do understand that you're not touting your experience with the DRPA as all encompassing. However you can't say, in the same breath, that the krell and/or an incorrect gain structure had nothing to do with your experience. To say that is to not understand gain structure.

There is nothing wrong with the Krell amp I'm sure, but it's simply the wrong tool for the job (at least the way it was being used). The amp quality is really of no significance when it's fed a by a crossover with a s/n ratio of 45db.

Please don't take this as argumentative, or criticism of your equipment. It's simply just matter of fact. :) Get those lights dancing (without clipping) and then, and only then, we can make a fair comparison.

boputnam
12-18-2010, 05:16 PM
:dont-know: ...

Steve71
12-20-2010, 09:54 AM
From Rane's web site on setting sound system level controls.


Correctly setting a sound system's gain structure is one of the most important contributors to creating an excellent sounding system. Conversely, an improperly set gain structure is one of the leading contributors to bad sounding systems. The cost of the system is secondary to proper setup. The most expensive system set wrong never performs up to the level of a correctly set inexpensive system. Setting all the various level controls is not difficult; however, it remains a very misunderstood topic.http://www.rane.com/note135.html

Tim Rinkerman
12-23-2010, 08:57 AM
Rane....!?:banghead: you've dragged this piece of crap Driverack out to ad nauseum, and now you are quoting techspertise from RANE!!!? The poor man's Behringer?! There are very few "pro" devices of any sort than can corrupt the signal chain merely by pushing the "in" button without actually using the device's features...Rane makes most of them....

Steve71
12-23-2010, 11:00 AM
Rane....!?:banghead: you've dragged this piece of crap Driverack out to ad nauseum, and now you are quoting techspertise from RANE!!!? The poor man's Behringer?! There are very few "pro" devices of any sort than can corrupt the signal chain merely by pushing the "in" button without actually using the device's features...Rane makes most of them....

Are you suggesting that the quote from Rane is incorrect? If so please enlighten me. Lets avoid the straw-man argument please - correct what was said, don't just discredit who said it.

Can you honestly say that Jerry Rig had his gain structure set correctly? Did I make a mistake with my 45db s/n calculation?

I'm more than willing to eat my words, but I'll need some facts please, not just a 'because I said so'. :)

And once again, in case you missed it the first time, I'm not suggesting that the dbx is the be all, end all. I'm just pointing out that the comparison was invalid due to the incorrect implementation.

Mike Caldwell
12-23-2010, 12:08 PM
Rane....!?:banghead: you've dragged this piece of crap Driverack out to ad nauseum, and now you are quoting techspertise from RANE!!!? The poor man's Behringer?! There are very few "pro" devices of any sort than can corrupt the signal chain merely by pushing the "in" button without actually using the device's features...Rane makes most of them....


I would never consider Rane "the poor man's Behringer" Maybe not my first pick but still way better than Behringer.

SMKSoundPro
12-23-2010, 01:27 PM
I have read this thread, and although I have a dbx 260, software and serial cable for my laptop, I have not installed it anywhere. The more I read online from people that work in the pro audio world, the less I want to use it.

That being said, I am currently doing some service work for one the mom/pop pro sound and lighting companies here and have received a sound rig that they send out on raves and other dj gigs that uses a dbx 260 and two qsc mx1500 amps to power four EVSx500s atop four EV eliminator single "subs."

I viewed the settings programmed by the architect of this setup and while running pink noise through it and using the dbx condenser mic for it, have realized that the this unit is fine for its use, but not for me. My bar manager boss was looking over my shoulder and saw my laptop plugged into the rig and thought "ooooohhh coool!" then I reminded him that we come from the record groove analog world and this dbx device apparently is not "exactly" garbage in = garbage out. He asked why "we" don't have them installed on all of our sound systems to keep the dj's from chewing up gear, and I explained that with all of the different stuff we have going on, its easier to reach over and grab a knob and twist it like our fathers did. He instantly understood and left me alone to figure these settings out.

Bottom line.
Thank you to dbx and all of the designers of DSP products, but using these seems to go against my signature line posted below.

Merry Christmas and Happy Holidays to all!

Scotty.

1audiohack
12-23-2010, 02:22 PM
I have four of the DBX 260's and for the money I think they rock. The more capability you load into something the more chances you give someone to make a disaster. There is a lot you can do wrong with them, and a lot you can do right. To make a blanket statement like "they suck, are noisy, kill all the dynamics" and so on indicate to me that something in the setup/ configuration / system is wrong and the owner / operator does not have the knowledge or patience to figure it out. It's pretty amazing what a knowledgable person with some real measurment gear can do in a hurry with one of these. With out the above mentioned assets it's almost gauranteed to be trouble.

The statement that Rane is the poor mans Berhinger is just bullshit.

Mike Caldwell
12-23-2010, 02:29 PM
The statement that Rane is the poor mans Berhinger is just bullshit.

You said it in fewer words than I did and a more to the point!

As for the DBX 260, good units, a huge step up from the Drive Rack PA. The only thing I would not use on them is the auto eq.

1audiohack
12-23-2010, 02:53 PM
As for the DBX 260, good units, a huge step up from the Drive Rack PA. The only thing I would not use on them is the auto eq.

Yup! Auto EQ, trouble for the unknowing with the push of a button.

boputnam
12-24-2010, 08:18 AM
...now you are quoting techspertise from RANE!!!? The poor man's Behringer?! There are very few "pro" devices of any sort than can corrupt the signal chain merely by pushing the "in" button without actually using the device's features...Rane makes most of them....+1.


The statement that Rane is the poor mans Berhinger is just bullshit.Golly, you're right too! They're both all that - and less! Never met a piece of either I wouldn't bypass - physically!


...you've dragged this piece of crap Driverack out to ad nauseum...+100...:applaud:

boputnam
01-07-2011, 03:39 PM
Did I make a mistake with my ... calculation?Uh, yeah, it would seem so.


I'm more than willing to eat my words, but I'll need some facts please, not just a 'because I said so'. OK.


The outputs on the dbx (+4dbu) will overdrive the inputs on a consumer amp (-10dbu).See, that there is wrong - you've blurred the units. It is +4 dBu relative to -10 dBV. You are changing reference levels (units), the former to 0.775 volts the latter to 1.0 volts. Remember, we only have conventions so we can change them! :p


To overcome this your only option ... is to use the dbx's digital gain controls. Now you've just reduced your s/n ratio by 14db. :no: When adjusting for units, the gain difference is 12 dB.

:)

Eaulive
01-25-2011, 09:29 AM
Sure you can, but since it's done in the digital domain, it's unless for setting up correct gain structure (unless you already happen to be in the ball park). IE it does nothing to reduce the noise the DRPA adds to the chain.

Words of wisdom.

In some installations I had to set the levels on the PAs to prevent a bozo from cranking them up because he wanted more volume, effectively using very little output from the driverack but that's not the way to go.

If you use a sensitive amp (like a consumer amp or a pro amp with the levels set to max) and reduce the output on the driverack, you are NOT reducing the noise caused by the D/A converter!
The right way would be to use the processor up to its full output or let's say 12dB down, and to reduce the gain on the amp or with a attenuator or a pad.

Steve71
02-07-2011, 09:16 AM
Uh, yeah, it would seem so.

OK.

See, that there is wrong - you've blurred the units. It is +4 dBu relative to -10 dBV. You are changing reference levels (units), the former to 0.775 volts the latter to 1.0 volts. Remember, we only have conventions so we can change them! :p

:no: When adjusting for units, the gain difference is 12 dB.

:)

Red herring! JR's Krell amp has XLR inputs so the voltage difference (between the dbx and amp) was an incorrect assumption on my part (this was discussed earlier in this thread).

However this (as already discussed) does not alter the fact that the input led's on the dbx did not get above -30dbu, which of course tells us the DRPA was not setup correctly (by a wide margin) for whatever reason.

This is a really open and shut case of user error and no amount of wishful thinking can alter that.

jerry_rig
02-07-2011, 02:08 PM
Red herring! JR's Krell amp has XLR inputs so the voltage difference (between the dbx and amp) was an incorrect assumption on my part (this was discussed earlier in this thread).

However this (as already discussed) does not alter the fact that the input led's on the dbx did not get above -30dbu, which of course tells us the DRPA was not setup correctly (by a wide margin) for whatever reason.

This is a really open and shut case of user error and no amount of wishful thinking can alter that.

Not that I have to defend myself to you on this forum, but I never said that in my installation the dbx did not get above -30db. Please do not be so quick to assume "user error." It will not make you many friends here.

Peace.

Steve71
02-08-2011, 09:50 AM
Not that I have to defend myself to you on this forum, but I never said that in my installation the dbx did not get above -30db. Please do not be so quick to assume "user error." It will not make you many friends here.

Peace.

From post # 22


Please don't take my comments as a bonafide review of the DriveRack. I was simply noting what I perceived as cleaner deep bass from the Ashly. All lights on the dbx indicated very low operating levels. As I recall only the first level was lit up. Note that the crossover is being used to match a pair of 2235s to my other speakers. All are driven from the same pre-amp and the low-end power amp does not have attenuation, so I don't have much flexibility to push (or limit) signal strength at the crossover. It is what it is...

The first level is -30db (see pic below)

I come here to learn and, on rare occasion to debate something I see is in error. I try to do that in a somewhat diplomatic manner and to let the facts speak. I do not wish to offend you, but If the truth offends you, then so be it. From the facts you presented here the dbx was not set up correctly. And if you don't consider throwing away a potential 45db of s/n ratio as user error, I'd hate to see what you do consider user error.

To be fair to you though, you were just using what equipment you had on hand. And you have stated many times that you're not presenting your impressions as the be all end all. I would be interested to know (1) if your pre-amp has XLR outputs and if so did you use them? And (2) if your pre-amp doesn't have XLR outputs, did you use the +4dbu/-10dbu sensitivity switch on the back on the unit? It's entirely possible that you did the best with what you had to worth with, but it's also entirely possible that you could have improved the s/n ratio a bit. However without an amp with gain controls, you're behind the 8 ball to start with.

jerry_rig
02-08-2011, 04:03 PM
I would be interested to know (1) if your pre-amp has XLR outputs and if so did you use them? And (2) if your pre-amp doesn't have XLR outputs, did you use the +4dbu/-10dbu sensitivity switch on the back on the unit?

My preamp is a Pass Labs XP-20 and I used the balanced XLR outputs to drive the crossover (and XLRs to the Krell). My recall as to the level readings should not be taken as gospel. I'm certain it was working properly. Now let's move on, please. Thank you.

Jerry

Steve71
02-09-2011, 01:17 PM
My preamp is a Pass Labs XP-20 and I used the balanced XLR outputs to drive the crossover (and XLRs to the Krell). My recall as to the level readings should not be taken as gospel. I'm certain it was working properly. Now let's move on, please. Thank you.

Jerry

I'm sorry you've lost me. How can you be certain that it was working properly, but also be uncertain as to the levels? The latter determines the former.

JeffW
02-10-2011, 06:52 AM
I'm sorry you've lost me. How can you be certain that it was working properly, but also be uncertain as to the levels? The latter determines the former.

If you were using a preamp to drive the DBX, the input LEDs would probably not all be lit unless the preamp was turned up quite a bit-ie a very loud listening situation. If you set the inputs to be all lit up at a normal listening level, the inputs would clip if you ever wanted to crank it up via the preamp.

It seem plausible that he could have it set up correctly and have only the lower LED lit if the preamp wasn't cranked up to 11.

Steve71
02-10-2011, 07:45 AM
If you were using a preamp to drive the DBX, the input LEDs would probably not all be lit unless the preamp was turned up quite a bit-ie a very loud listening situation. If you set the inputs to be all lit up at a normal listening level, the inputs would clip if you ever wanted to crank it up via the preamp.

It seem plausible that he could have it set up correctly and have only the lower LED lit if the preamp wasn't cranked up to 11.

I have mine setup such that it doesn't clip when cranked, but at 55db (background levels) it still lights up the -30dbu lights. And it's only with fine gain controls on all the amps that I can get the volume range where it needs to be while keeping the input/output leds where they need to be.

Ideally you'd keep your pre-amp fixed and adjust for volume after the dbx with a multichannel volume control. However these are expensive and hard to come by.

Let's be clear though, there is a big difference in s/n ratio between a setup that lights up the -30dbu lights at high volume and one that does it at 55db. I've had my system setup both ways (before I bought the right amps for the job) and there is without a doubt a difference in sound quality.

Actually, if your amp doesn't have gain controls you can get around it by building custom XLR cables (between the dbx and power amps) with a simple voltage divider circuit to reduce the output after the dbx. I did this for a while but in the end gain controls offer more control.

boputnam
02-10-2011, 07:12 PM
This is a really open and shut case of user error and no amount of wishful thinking can alter that.Ouch! A spanking! Odd...


Please do not be so quick to assume "user error." It will not make you many friends here.Boy-howdy to that. Agreed. There are ways, and then there are better ways.

If one loses their inquiring students, they are no longer teaching as no-one is listening...

Steve71
02-11-2011, 01:40 PM
There are ways, and then there are better ways.

And there are wrong ways, and mostly wrong ways and partly, sometimes wrongs ways... ad nauseam.

Call it what you will, it is what it is - A system with a poor gain structure such that the s/n ratio off by a potential 45db or more depending on where the volume control is. Shall I email dbx's tech support and see if they think a max signal of -30dbu is acceptable?

From the dbx manual - second to last page of the appendix - link

http://www.proliveaudio.co.uk/Web%20Manuals/x%20overs/PA%20DriveRack%20Manual.pdf


One thing that is critical to system setup is maximizing gain structure. Gain structure refers to
aligning the gain of each device so that they all clip at the same point, and the noise floor of
the entire system is at its absolute minimum. Quite often PA systems are setup with the amplifier
input controls turned all the way up in the incorrect assumption that this is the only way
to get the maximum output level.Note that the Krell amp in JR's system does not have gain controls and as such falls into the incorrect 'input controls turned all the way up' category.

Notice too how they said, "Critical" and "maximizing gain structure" in the same sentence.



If one loses their inquiring students, they are no longer teaching as no-one is listening...

Regardless, the truth is the truth. If people want to stick their fingers in their ears, it's their loss, not mine.

Allanvh5150
02-11-2011, 09:39 PM
The last time I used one of these in a SR situation, I was having problems with trying to get the vocals to come through. I found myself pushing the hell out of 800 - 1400 on the desk. I asked the in house guy about the crossover frquencies he was using and he gell fully replied 200hz and 1600hz. The system consisted 2240's 2225's and 2445's. I was having doubts about the performance of his driverack and then it all became clear. I asked why he chose 1600 as a crossover point and he commented that it was the optimum for the gear he was using. He then asked what I would use and proceeded to roll around on the floor when I replied 800hz......he started rambling about feedback and blowing drivers.....oh well. each to thier own........
Many people confuse poor performance with poor setup. The driverack stuff is great when used as intended but as with most things, can sound like bum if the setup is poor.

Allan.

Mike Caldwell
02-13-2011, 11:12 AM
1600hz to go from a 2225 into a 2445, not so bad'ish! 800hz to go from a 2240 into a 2225 WAY off!!!!!!

Eaulive
02-13-2011, 02:06 PM
1600hz to go from a 2225 into a 2445, not so bad'ish! 800hz to go from a 2240 into a 2225 WAY off!!!!!!

I had the same reaction when I read this post, but after re-checking I think he meant 800 instead of 1600 from the 2225 to the 2445, keeping the 200Hz point between the 2240 to the 2225.

Allanvh5150
02-13-2011, 02:57 PM
ummmmmm yes. I would normally use 80, 800, 8000. 1600 crossover point creates a big hole considering the max usable frequency of 1200 for the 2225, I may be wrong. 800 hz is the norm and in fact many JBL systems crossover at 500.

Allan.

Mike Caldwell
02-13-2011, 03:25 PM
The system he described was a three way system. The low frequency point coming out of the 2240 going in to the 2225 give or take around a 100hz is a good starting point. The 2225 was rated out to 2000hz, granted out that high it's starting to beam. 1200hz to 1600hz would work and give the driver some extra power handling for a PA system use. The type of horn on the driver would also have a bearing on the crossover frequency used.
I''m also assuming that the 2240's and 2225's direct loaded reflex type cabinets.

My gut feeling is that that system also had other issues as well!!

boputnam
02-16-2011, 01:27 PM
The last time I used one of these in a SR situation...All too often they are deployed poorly in SR. I always go straight to the DSP and start paging through the settings to see what's "in my way". More often than not, like you say, Allan, common sense is not given enough credence.

Typically, I see well intentioned set-ups that the on-site system guy has no or little involvement in, or understanding of - there have been times an outdoor "program" is being used in a shed or tent. There was no measurement gear being used during system tuning. No, or wrong, group delay. Yikes... And they freak if I start editing. I explain my thoughts, save their settings one-more-time for good measure, and start editing - quickly - 'cause it's got to be done during our staging. Invariably, after our set, they ask me to save my config so they can use it in future.

Like you say, these are powerful devices, but the SR realm is a wasteland of bad execution. It's all about physics...

Mike Caldwell
02-16-2011, 01:39 PM
And lets not forget about "Auto EQ":crying:

Eaulive
02-16-2011, 04:05 PM
And lets not forget about "Auto EQ":crying:

Auto EQ is not bad but one has to check what its trying to do and confirm the results.
Sometimes at crossover points there are some disturbances created by uneven delays and trying to EQ this often gives worst results than letting them be.
If the auto EQ wants to give a sharp boost or cut near crossover frequencies, beware.

1audiohack
02-16-2011, 10:16 PM
And lets not forget about "Auto EQ":crying:

Oh but I think we should, in fact, I did. :p

Tim Rinkerman
02-18-2011, 04:40 AM
Have any of you worked with "engineers" who could quote the spec's of any piece of equipment from the last ten years from memory, then when it came down to mixing time produced a mix that sounded like a dog mixed it with earmuffs and mittens on?
I come back to this thread every once and a while.... just like picking a scab that's not ready to come off....
I'm just not getting how somebody could spend the money on Krell, and Passlabs...understanding their quality...then put a Driverack in between them....
The best audio paths have the fewest things in them.....if you're almost out of things to argue about gain wise, try measuring how long it takes for the original signal to make it through a Driverack....if you really pay attention to the details and get over this gain BS, you would realize what a piece of crap this unit is. Think "digital delay"...

1audiohack
02-18-2011, 06:44 AM
And if I know the answer to that question, what in your mind does that make me? A technogeek hamfisted mix masher with cloth ears? :)

I haven't had a DRPA for years, but if I remember correctly, the latency of that unit with all the programmable signal delay turned off is 1.4ms. I measured it myself.

Allanvh5150
02-18-2011, 11:53 AM
Have any of you worked with "engineers" who could quote the spec's of any piece of equipment from the last ten years from memory, then when it came down to mixing time produced a mix that sounded like a dog mixed it with earmuffs and mittens on?
I come back to this thread every once and a while.... just like picking a scab that's not ready to come off....
I'm just not getting how somebody could spend the money on Krell, and Passlabs...understanding their quality...then put a Driverack in between them....
The best audio paths have the fewest things in them.....if you're almost out of things to argue about gain wise, try measuring how long it takes for the original signal to make it through a Driverack....if you really pay attention to the details and get over this gain BS, you would realize what a piece of crap this unit is. Think "digital delay"...

The driverack is a piece of equipment with a purpose. If everyone went for the minimal length audio path, we would still be using Edisons original phonograph.

Allan.

MikeBrewster77
02-19-2011, 07:51 AM
...we would still be using Edisons original phonograph

Which would actually sound better than some of the crap systems people cobble together these days, but I digress...

Eaulive
04-27-2011, 01:52 PM
Got mine a couple of days ago, no noise problem so far and the pop/surge that was audible and destructive with the driverack PA is completely solved in the driverack PA+, and I got mute buttons to boot :D

I will report if any noise is heard when I connect my more sensitive speakers.