Quick question: can LM4562 op-amps be installed straight to DCX in the place of old op-amps? Have somebody tried them? LM4562's specs look pretty damn good, definitely more capable op-amps than originals. I like the low input noise (only 2.7nV/ √ ^Hz (typ)) as it reduces the hiss(?).
Could someone write a little summary of desoldering/resoldering of SOIC op-amps? How it is done the most convenient way (is there such)?
I've upgraded a few units with the National LME49720 (LM4562) replacing NE5534s and JRC2068s so far. Not had any compatibility issues yet...
I'll be finding out the answer to this question in the next week or 2 when I start modding my brothers spare DCX2496. The plan is to re-work the input and output circuits to remove the electrolytic caps, replace the ICs, reset the gain to levels useful for home use, and add a motorized Alps 6 channel pot for volume control.
So far I've removed the electrolytic caps and replaced the NE5534 ICs with LME49720 ICs on 2 M-Audio audiophile 192 cards to good effect.
On the Layla 96/24 that currently is the DAC in my system I've removed the electrolytic caps, reset the gain, and replaced the JRC2068 ICs with LME49720 ICs. This was done in several stages. In my system I'm only using 4 of the 8 outputs of the Layla so far. First was removing the electrolytic caps on 4 output channels. I have the outputs duplicated so output 1 and 5 carry the same signal, 2 and 6, etc. This allows us to swap between the modded circuit and stock circuit on the fly. Removing the electrolytic caps provided an improvement that is pretty normal for that mod. After the verification of the success of the mod the output caps on the other 4 channels were removed. Next was reducing the gain so that not as much attenuation was needed. The gain of the balanced to SE converter stage was reduced so the maximum output was reduced from 9.5Vrms to 2.2Vrms. This was not done in 2 stages. After a couple of days the next mod was replacing half the output ICs. Once again we can listen to the outputs either through the National LME49720 ICs or the JRC2068 ICs with all the rest of the circuit the same. This mod made a large improvement in clairity and depth of presentation. Much larger improvement than replacing the NE5534 ICs with the LME49720 ICs in the M-Audiio cards.
So after I measure the stock BehringerDCX2496, measure my modded DCX2496 that has the alternate input circuit shown on my web page I'll mod up my brothers unit and re-measure it.
For changing SO8 SMT ICs without a proper hot air setup one way that works well and is pretty safe is to use a small pair of fine point flush cutting wire cutters to cut the legs off the body of the IC. After the body of the IC is gone you can use fine point tweezers and a fine point temp controlled soldering iron. Using the tweezers you can remove the leads of the IC from the pads. Clean the pads with fine solderwick. Place the new IC on the pads verifying direction, then re-solder with fine .5mm no wash solder. Needless to say, you must have a very delicate touch during all the steps listed above. We used this way during prototyping SMT circuits many years ago before we got all the nice hot air re-work tools.
I have an old hot air station at home now for the work I'm doing on the sound cards and CD players.
Gary
I'm lucky enough to have a hot air station. I would not be without it. Also works well for new SMD boards with paste solder.
The parts can be removed without the hot air, but it's a real pain.
I did some measuring today of stock vs modded outputs. At first glance it looks like the modded outputs are better - lower noise, lower distortion. But I'm having some FFT problems that need to be worked out before I can be sure. Gary, check your email.
The parts can be removed without the hot air, but it's a real pain.
I did some measuring today of stock vs modded outputs. At first glance it looks like the modded outputs are better - lower noise, lower distortion. But I'm having some FFT problems that need to be worked out before I can be sure. Gary, check your email.
Just to join the chorus - hot air gun is a ticket for the job. Desoldering is a breeze with it. Without hot air gun it is almost given that you might destroy the tinny PC board traces. All what it takes is small push when not all legs are desoldered enough and your trace is history.
But on the other hand I had just a pain using hot air gun for soldering. Pano, I had very little success soldering with the hot air gun because very often, after heating, my solder paste would melt to the places not easily seen like underneath the chip and would create shorts. I tried and tried and in my case it never worked well. What works really well for me is very thin solder, I mean the thinest you could fine and liquid flux. Liquid flux is the key player here because it keeps the chip in place before the first leg is soldered, almost like a glue, besides its originally intended purpose.
Important fact not mentioned here is - do not even try doing it without a proper viewing magnifier. There are microscopes made for this purpose, but for the home use I would recommend binocular magnifier with LED lights and something with stronger magnification - like 8x magnification. Without that ... do not even bother doing it.
But on the other hand I had just a pain using hot air gun for soldering. Pano, I had very little success soldering with the hot air gun because very often, after heating, my solder paste would melt to the places not easily seen like underneath the chip and would create shorts. I tried and tried and in my case it never worked well. What works really well for me is very thin solder, I mean the thinest you could fine and liquid flux. Liquid flux is the key player here because it keeps the chip in place before the first leg is soldered, almost like a glue, besides its originally intended purpose.
Important fact not mentioned here is - do not even try doing it without a proper viewing magnifier. There are microscopes made for this purpose, but for the home use I would recommend binocular magnifier with LED lights and something with stronger magnification - like 8x magnification. Without that ... do not even bother doing it.
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Thanks. How many should I order? If I remember correctly there are 3 visible DACs on DCX, are there any on the other side of the digital board?
3 dacs
There are 3 dac chips. They have very small pitch legs and are easily damaged from heat if you decide to try it. The AK4396 will drop in and sound much better with a deeper, more transparent soundstage. The AK4395 is slightly better still but requires lifting the leg of pin 2 to connect an additional 5v supply as the 4393 and 4396 run on 3.3v. I haven't auditioned the comparisons with the stock output circuits but when listening direct out from the chips it is easy to hear that the newer dacs have much better resolution and their lower ultrasonic noise spectra is better suited to running with no filtering.
I decided to give it a try. I also ordered some chinese hot air station from ebay for easier removal
Can you recommend any straight fit 47µf audio capasitors for DCX? I can't find any same sized with originals.
Thanks for all replies.
Does anybody know a cheaper source for LM4562s than future electronics? Shipping fee is quite big to Finland, 33% of the total price.
What capasitors would you recommed to be used in I/O board?
Also AK4396 DACs would be nice but I cannot find a source for them.
Digikey is a National dealer. Not sure if they're cheaper than Future, but you might want to check. They definitely do ship internationally.
Now im very bad a maths and sure electronics, but the AK4393 output is 2.5V
do the 1K load loose that much?
I run my dcx with passive mod out to Tripath TA3020 with 50k input impedance.
Does it matter?
Is there any formula for output-input impedance?
Main drawback of the JRCxxx opamps of DCX is not their sonics IMO, but their low PSRR making decoupling and (power line) trace layout crucial – also look here :
http://www.diyaudio.com/forums/multi-way/15943-behringer-dcx2496-digital-x-over-6.html#post597703
Its been a while that I've been hunting opamp data sheets - but boy ! – this LME49720 is a sports car !!!
Thanks for pointing there, Gary.
###########
Regarding de-soldering SMD I have another variant / trick to add
Use a standard iron and put a loooot of solder on each side, so that all pins each side are covered completely
Then melt both sides at once - which is fairly easy for a 8-pin device - and lift.
You will damage neither device nor traces if you have some experience in soldering.
Don't try with bigger IC's like the DAC....
As for SMD soldering, I had good luck with special SMD non wash flux (that's sold as injection) and 0.5 mm solder plus a extreme fine tip (all from ERSA) - being able to even successfully re-solder SO-DIMM socket on notebook mobo (roughly a 200 pins at 2" IIRC)
I wouldn't recommend for anyone to try unless you have a loooot of experience, tho (the SO-DIMM re-soldering meant only) !
Anyone who has succeeded to get that built in digital attenuation to work in DCX (AK4395 = full 127dB ! ) ?
Michael
http://www.diyaudio.com/forums/multi-way/15943-behringer-dcx2496-digital-x-over-6.html#post597703
Its been a while that I've been hunting opamp data sheets - but boy ! – this LME49720 is a sports car !!!
Thanks for pointing there, Gary.
###########
Regarding de-soldering SMD I have another variant / trick to add
Use a standard iron and put a loooot of solder on each side, so that all pins each side are covered completely
Then melt both sides at once - which is fairly easy for a 8-pin device - and lift.
You will damage neither device nor traces if you have some experience in soldering.
Don't try with bigger IC's like the DAC....
As for SMD soldering, I had good luck with special SMD non wash flux (that's sold as injection) and 0.5 mm solder plus a extreme fine tip (all from ERSA) - being able to even successfully re-solder SO-DIMM socket on notebook mobo (roughly a 200 pins at 2" IIRC)
I wouldn't recommend for anyone to try unless you have a loooot of experience, tho (the SO-DIMM re-soldering meant only) !
Anyone who has succeeded to get that built in digital attenuation to work in DCX (AK4395 = full 127dB ! ) ?
Michael
slow filter
We would need to change to a serial controller and could then also select the slow filter.
I decided to get Elna silmic IIs for capping. I will change the whole capasitor reserve on both I/O card and digital board with them.
For PSU I got some pretty basic Nichicon caps (NICHICON | UPJ1C122MHD | PJ Series 1200 uF 16 V 20 % Through Hole Radial Aluminum Electrolytic Capacitor - Future Electronics to replace the 1000µf caps in PSU and NICHICON | UPJ1E471MPD | PJ Series 470 uF 25 V 20 % Through Hole Radial Aluminum Electrolytic Capacitor - Future Electronics to replace the 470µf caps) that are optimized to use with switching power supplies.
As said, I decided to get also Ak4396 DACs to replace the stock DACs and LM4562s to replace the stock op-amps.
I will do the modding in phases and take measurements and listening impressions after every mod. The order in which the mods will be done has not yet clarified to me.
What other (and easy) mod besides ferrites and capping could one make to original PSU, suggestions?
For PSU I got some pretty basic Nichicon caps (NICHICON | UPJ1C122MHD | PJ Series 1200 uF 16 V 20 % Through Hole Radial Aluminum Electrolytic Capacitor - Future Electronics to replace the 1000µf caps in PSU and NICHICON | UPJ1E471MPD | PJ Series 470 uF 25 V 20 % Through Hole Radial Aluminum Electrolytic Capacitor - Future Electronics to replace the 470µf caps) that are optimized to use with switching power supplies.
As said, I decided to get also Ak4396 DACs to replace the stock DACs and LM4562s to replace the stock op-amps.
I will do the modding in phases and take measurements and listening impressions after every mod. The order in which the mods will be done has not yet clarified to me.
What other (and easy) mod besides ferrites and capping could one make to original PSU, suggestions?
I'm doing 4396's and LM49720's, but reconfiguring the output buffers with .1% resistors as differential amplifiers to remove the 2.5V offset. That way I can drop the coupling caps entirely.
Cheers,
Paul
I'm not sure about a digital volume control. Could it be done in the DSP? To do it in the DAC chips you'd have to put in the AKM4396 and probably rewire a good bit. The 4393 is in parallel mode, you'd probably want serial mode to control to control the volume, filter, etc.
I'll have to search back through the thread to see what has been done.
I've been trying some measuring of the DCX with transformer outputs vs stock output. It's still very difficult to do. Indications are that noise and distortion are lower with the transformer, but not thru the whole spectrum. 3rd order distortion increases at higher frequencies on the stock output, and increases at lower frequncies on the transformer outputs.
I'll keep trying to make sense out of it. I'm not having much luck with the Arta/Steps measurements. Too many glitches.
I'll have to search back through the thread to see what has been done.
I've been trying some measuring of the DCX with transformer outputs vs stock output. It's still very difficult to do. Indications are that noise and distortion are lower with the transformer, but not thru the whole spectrum. 3rd order distortion increases at higher frequencies on the stock output, and increases at lower frequncies on the transformer outputs.
I'll keep trying to make sense out of it. I'm not having much luck with the Arta/Steps measurements. Too many glitches.
I was thinking and comparing notes between the Behringer2496 and the Echo Layla 96/24 that I'm currently using as a DAC. Both circuits start off with the standard cookbook output stage as listed in the AKM data sheets. Echo uses just the balanced to single ended converter and configures the output as a single ended drive balanced output (is there a name for this configuration?). Very simple and sounds good. Behringer adds 2 more stages to create the virtual transformer output.
It would not be hard to remove a bunch of circuitry from the Behringer output stage and configure it like Echo does. With this output stage configuration the output can drive either balanced equipment or single ended equipment without the complexity of the Behringer output stage.
Here is what the output stage of the layla looks like including the stock version and the mods I've incorporated so far
I'm going to try this out on my brothers Behringer with a twist. We are going to add a 6 channel motorized alps 100K pot purchased from a vendor in Hong Kong. The pot includes a driver board and an infrared remote for ~$50.00. The 100K value is too high to be of use directly but we are going to use the second half of the output chip as a buffer to drive the newly created single ended driven balanced output.
Gary
It would not be hard to remove a bunch of circuitry from the Behringer output stage and configure it like Echo does. With this output stage configuration the output can drive either balanced equipment or single ended equipment without the complexity of the Behringer output stage.
Here is what the output stage of the layla looks like including the stock version and the mods I've incorporated so far
An externally hosted image should be here but it was not working when we last tested it.
I'm going to try this out on my brothers Behringer with a twist. We are going to add a 6 channel motorized alps 100K pot purchased from a vendor in Hong Kong. The pot includes a driver board and an infrared remote for ~$50.00. The 100K value is too high to be of use directly but we are going to use the second half of the output chip as a buffer to drive the newly created single ended driven balanced output.
Gary
never done
Nothing has ever been written anywhere that I know of regarding a conversion from parallel registers to serial control of the AKM dacs.
Hi AR2
When you have issues with the solder stringing under the parts it's generally caused by trying to melt the solder paste too fast and/or too much air flow. After the solder paste is applied and the new part has been placed on top of the paste start pre-heating the part and board with the air nozzle a couple of inches above the part. The usual string of events involves a slow pre-heat where the flux gets runny and the solder paste slumps a bit. Hold this heat level for awhile. The carrier in the flux will evaporate and the flux will thicken and the solder paste will start to look dry. This is the time to start moving the air nozzle closer to the part to do the final heating to melt the solder. When all the solder is molten you can gently tap the board and the part will center itself on the pads while it is floating on the molten solder. Taping the board to see the part move is also a good way to check to see that the solder on all the leads has melted.
I could not agree more! Old age and SMT don't mix... I've got magnifier lamps on all my work benches, and a B&L binocular microscope that does 10x to 25x magnification.
Gary