DCX2496 - Is it a good compromise vs a CX3400 + DEQ2496 pairing?
Marshall.
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DCX2496 - Is it a good compromise vs a CX3400 + DEQ2496 pairing?
Marshall.
Only vs the CX3400 IMO. The DEQ is a very versatile unit itself and for some of us can even function as a useful stand alone basic analysis tool.
The DCX while touting a parametric EQ function really only offers one band of EQ per output and input channel, and the extent to which you can push the parameters is very strictly limited by the amount of internal memory in use. Probably best to look at it as a crossover only, as it cannot really perform the function of a stand alone EQ, and certainly not one like the DEQ.
Another thing to consider is that the DEQ can be connected to the DCX in the digital domain maintaining the minimum in A/D-D/A conversions.
Just my .02....................
The DEQ/DCX combo is quite good however.
D/A is where quality generally degrades, so straight digital between the two.
Bear in mind the 96 kHz of the Behringer vs 48 for most units in that price range...
Very helpful, guys.
The DCX2496 is $AU230 more than the CX3400 at Downunder best prices. I guess I will have to look at the benefit of spending the extra amount, giving consideration to my ageing ears and whether they would benefit from the digital to digital transfer.
The Luddite in me likes the fact that the CX3400 has KNOBS.
Mmmm?, Marshall.
My goodness...this is not true!Quote:
Originally Posted by bowtie427ss
Page 3...the parameter "NR", when highlighted...simply rotate the adjustment knob and a brand new band of EQ is added.
I've had multiple bands, slopes and shelves on all outputs of a stereo three way setting and was able to do all required work to bring the multiple speakers/transducers into balance. This is why I have not had the need to add the DEQ.
I'm pretty sure you would be intrigued at how easy the dcx is to operate...Quote:
Originally Posted by mah
The DCX is an amazing bit of kit. It does so much for so little money. Nothing else comes close. I also use the DEQ.
The DCX is not without its problems, tho. A lot of that is the output circuits, they just don't sound great (and I have measurements to prove it). Fixing those is a whole cottage industry. The digital input and clock can be improved, as well as the power supply. All that will cost more than the DCX, maybe 3X more - but in the end you'll have a superb crossover/DAC that can do what no other can.
Highest priority IMO is the analog outputs.
The DCX works fine into pro type gear...
Worth a read here...
Why modify the Behringer DCX2496 ?
http://www.linearaudio.nl/6chan-1.htm
The second site you linked to is Jan Didden. A good and knowledgeable fellow. I think Jan will be in Austin next month when I'm there. It will be nice to meet him.
I have read comments elsewhere stating the DCX2496 is noisy when used in home-type equipment because of lower drive levels. Has anyone noticed this?
I am concerned that this may be an issue with a 802/511B combination.
Would this concern also apply to the CX3400?
I have an almost completed DIY analogue LR crossover but thought I would look at the Behringer units because they include time delay. I have to say that the possibility of audible noise is a worry.
Marshall.
This is a misnomer that has been generated around the web.
But there is an element of concern because of the very high efficiency of altec drivers.
Keep in mind the drivers I use are much more efficient than yours and noise
would be a bigger issue in my case.
Two important steps to succeed with a digital crossover like the dcx.
1) pump maximum signal into the crossover to ensure the signal is converted
to attain maximum resolution
2) attenuate the output signals from the behringer feeding the power amps.
If the amps you are using have an attenuator knob you are good to go.
The amps I purchased for my setup did not so I needed attenuators between the xo
and the power amps. I purchased these from Scott Endler and they work like a dream.
My system uses a stock behringer unit with the highest efficiency drivers altec
made and there is NO noise. Nothing. Dead silent. Which is creepy when the music
kicks ins. It's all about proper gain staging and listening to GM, bfish, old guy, pano and
all the other nut cases who visit here when you want to design a speaker system correctly. ;)
Thanks, Steve. My system will use domestic HiFi SS integrated amplifiers. One amps' 'pre-amp out' will connect to the crossover input. The crossover outputs will connect to the respective 'main amp in' of the 2 or 3 amps used.
Will this arrangement be OK? Would a simple boost stage between the pre-amp and crossover be necessary?
Marshall.
Do the power amps have a volume knob?
Yes means you have no worries.
No means you might have a bit of tweaking to do...maybe...maybe not.
Also you say you're going to use the pre out of an integrated amp to feed the crossover?
So you have no plan to use the power amp in the integrated amp?
It's all about gain structure, Marshal. If not used right, the DCX (and some other pro gear) can be noisy. But not if you do it right.
Here is a little something I wrote on the subject. Pano's Scribblings
Steve, I think the volume control on these integrated amps is in the pre-amp stage.
What would I need to do?
Marshall.
Pano,
Thanks for the gain-staging articles. I used to write policy, procedural and work instruction documents and I am impressed by their clarity of yours.
Flattery aside, here are the integrated amp specs. I have to work with:
Amp 1 - 'Pre-amp out' (1Volt) which would be the drive to the crossover.
Amp 1- 1Volt into the Main(power)-amp > 35W RMS per channel(8 Ohm)
Amp 2 -1Volt into the Main(power)-amp > 50W RMS per channel(8 Ohm)
Amp 3- if used, similar to Amp 1.
Do I need to provide boost for the input and attenuation for the output of the crossover or is there a way to make this all work in a home application using the crossover without add-ons.
Marshall.
Thanks Marshall. I used to translate user manuals into French and we always tried to make them better than the originals. Sometimes we actually succeed. :)
With a sensitivity like that it's not going to be easy to stay clean. These pro crossovers are really meant for power amps with a volume control up front. Even if you were to modify the DCX to bring the outputs down to the same level as the DAC chip output (about 1.7V RMS) you'd want to attenuate before the amp. I certainly need to in my rig.
On the older integrated amps I've owned, the volume seems to be the last thing in line. So for example coming in the tape monitor is subject to volume control. You think yours are not like that?
Of course you could build attenuation into your cables.
EDIT: Come to think of it, 1V out of the preamp seems low. A CD player is usually 2V out. Do you have a way to measure this?
With only the DCX spec sheet to go by...Quote:
Originally Posted by mah
+22dBu max input (and output) = ~9.7V, so disregarding EQ cut/boost, 1V in should produce 1V out. Both (really all 3) connections are low-to-high Z too, so no problems with loss or loading. Should be a smooth insert. You may have to tweak the gain a bit on the 2nd amp to balance the output for relative gain.
RE noise, I suspect you'll have some, but mostly from the amps. The common setup uses amps at full gain with adjustment at the pre level, which invariably leads to HF hiss (thermal noise) audible during quiet passages or between cuts. Your planned setup (may) beat that rap. If not, you can join the rest of us that learn to ignore it. ;)
Added
I'd check your amp 1 I/O loop to ensure the level varies with the volume control. I have an old (Kenwood) with that loop, and it doesn't...
Yep, 1 volt in will give you 1V out. If you don't change the gains inside, it is unity gain (no change)
Of course once you start dividing up the spectrum, each output is now a fraction of the full spectrum and thus lower in level. That will be very dependent on signal and crossover points, of course. Driving the DCX with a hot input helps keep the signal up out of the noise floor. The noise floor has been a big problem for folks using the DCX straight into power amps with no attenuation.
It really was not designed to be used that way - that's its major drawback for home Hi-Fi use.
Right, there's one thing that I just remembered any user should know:Quote:
Originally Posted by Panomaniac
Section 5: Audio Connections
The BEHRINGER ULTRADRIVE PRO DCX2496 has standard electronically balanced inputs and outputs. The circuit design has an automatic hum suppression with balanced signals and is able to operate, without problem, even at highest levels. Externally- induced mains hum etc. is thus efficiently suppressed. The servo- function, also automatic, recognizes the connection of unbalanced pin assignments and changes the nominal level internally so that there is no difference in level between the input and output signals (6 dB correction).
Feeding an unbalanced input on a power amp....well this means the behringer kicks up the signal when it recognizes an unbalanced connection. I forgot to note that the attenuators I purchased also presented a balanced load to the behringer, tricking it into thinking it is feeding a balanced input...thereby preventing the signal from being doubled. Easy to do with resistors....but necessary to get the best result possible.
The confusing part of behringer's documentation is the part in section 5, figure 5.1 where they say for unbalanced use pin 1 and pin 3 have to be bridged...which is simply not true...they should probably re-word that.
There is a lot of talk about how to wire the DCX for unbalanced. Tie 3 to ground, leave 3 open, tie 3 to ground via 10K, 20K, 50K and others. I've tried them all.
What actually worked by far the best for me was a transformer on the XLR output. But of course that was the biggest, heaviest and must expensive option.
Your balanced resistor attenuator should work well. Let us know!
Problem solver???
Pro Audio Gear: ARTcessories CLEANBox Pro Dual Channel Level Converter
Marshall.
Not if freq response/bandwidth is a concern. The posted specs are BS, many folks have measured the clean box and it has no business in a "hifi" system.Quote:
Originally Posted by mah
Just my .02......................... i'm sure someone here will think it's wonderful.
Is there something that does the conversions but of suitable performance?
Good question. The attenuation isn't a big deal, but the level shift up for the input is nice. It's what a preamp should do anyway.
Are you sure your preamps don't have enough gain and headroom to run a strong signal into the DCX? Can you measure? Or look at the input meters on the DCX? If you need a reference level tone, we can get you one.
I have found some relevant material on the net which I will post tomorrow for comment.
My amps, Sony 1120(made 1965-1968) and Sony Vfet Ta-4650(1974-1978), were both Hi-End, low-noise models in their day- definitely pre CD, definitely 1V out/in @ pre/main.
As I said, previously, I am a bit of a Luddite. Used Classic gear at budget prices also suits my level of disposable income. Buying a dcx3400 would be a big deal for me, so I want to get it right.
Until the morrow, Marshall.
Honestly, you don't want anything active between the XO and power amps.Quote:
Originally Posted by mah
It is extremely cheap to wire in your own resistors in an attenuator and wrap it up like the Endler attenuators do. You can use some cheap slider pots until you get the appropriate levels and then pull the pots and install fixed values for your application. I paid between...I think 65-75 for each attenuator but he custom made them, used top notch components, did very professional work. If I was interested in price, I could have done this easily...and I think so could everyone here with a little soldering skill. Transformers work...but I thought only attenuation was needed not isolation. Depending on the amp you feed...maybe this has merit. But resistors are the cheapest route.
Yeah, I like Steve's idea. Use pots to find were you need to be then replace them wit fixed resistors.
So you think the Sonys don't have any gain in the preamp circuit, yeah? Could be. Some of my vintage Pioneer and Sansui gear was like that, the pre outputs were really just after the selection switch. Volume, gain and tone were downstream. Too bad.
You kinda-sorta need a preamp to drive this rig. It would have input selection, gain, volume and any other gadgets. The output of that would go to the DCX. Or am I misunderstanding you signal flow?
OK Marshall, I went back and reread you posts in this thread.
Steve Summed it all up beautifully in post #11. Here is a good quote.
Quote:
Originally Posted by Steve Mac
What I'm not sure about is this:
OK, is the pre-amp out actually volume controlled on this amp? Have you checked? If it is, it probably also has gain, maybe 10dB, That's good and will help you with Steve's point #1. If the preamp outs are not variable, you'll need a preamp that has that.Quote:
Originally Posted by mah
Steve's point #2 will be taken care of with your other amps because they have a volume control. So you can run a hot signal thru the DCX and turn it down at the amp. That's ideal.
Click on this link then click the TA 4650 download link for the service manual. Pages 2,3 & 4 have the specs and cicuit block-diagram. There is only one volume control and it is in the pre-amp section.
I think it is worthwhile to proceed with purchasing one of the crossovers to place directly in the pre-main loop.
If it is noisy I can boost the input to the crossover with a matching-amplifier or matching-transformer and then attenuate the crossover output passively. Am I correct?
Marshall.
Steve, Are you using a consumer pre-amp direct to the DCX2496 input?
Could you give me schematic of a suitable output attenuator?
Marshall.
OK, got the manual. The preamp outs are indeed after the volume, balance and tone controls. Good!
Just wondering how much gain and headroom the "flat amp" section of the preamp has. That's Q201, Q202 on the left channel.
I run digital to the dcx.Quote:
Originally Posted by mah
For the attenuator...this might be wrong...just threw it together.
Maybe the guys here could review it but it should look something like this:
http://www.hostboard.com/forums/hbmc...2010/09/42.jpg
Yeah Steve, that will work and is pretty much what I've done in the past.
Fortunately Marshall dos not need the attenuation, as he is going into integrated amps with volume control. So he need only connect to pin 2 (hot) and pin 1 (earth). A 50K resistor could go from pin 3 to ground as a "courtesy" to the op amp that drives that pin. Might reduce noise a tiny bit - or not.
If Marshall can measure the gain of his Sony preamp, then we will be doing great!
Nice drawing Steve. Bal/unbal conversion and pad in it's simplest form.
The old Altec letter;
http://alteclansingunofficial.nlenet.net/publications/techletters/TL_133.pdf
gives the values and formulas for level pads. Note the use of dBm for reference. a power-referenced unit (expessed in mW) that assumes ~matched impedances for maximum power transfer. (That was the good ol' days where such things were important). Now, with the gear you encounter having I/O Z all over the map, we just throw extra power at it and burn off the waste. For that, the voltage referance units of dBv and dBu prevail.
Thanks, guys, for your help.
I am now happy to purchase a CX3400 or a DCX2496. Now to decide which one.
Regards, Marshall.
It basically simple (CX) vs flexible (DCX).
Agree. At a cost($s) of course. The DCX2496 is tempting.
By the way, I came across this. It may be of interest to DCX2496 users.
Expanded Soundstaging and 3D-Imaging
One man's overview of his DCX2495.
Balanced Three Way System
Great thread on active crossovers and the DCX2496, in particular. I was contemplating this same purchase so it's very timely.Quote:
Originally Posted by mah
I have been using the CX-3400, using a Yamaha C2a preamp, Pass F5 or other amps for highs, and a JBL/UREI power amp on the lows, driving Altec 802g and 416b. I was not experiencing any noise through the crossover at any listening levels. I was using combinations of balanced/unbalanced terminations. This has been my first go at using an active crossover and I see no reason to change, the active system delivers.
Besides the additional functions of the DCX2496, is there any difference in sound quality compared to the CX3400?