Edirol R4 pro op amp replacement

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lamacchiacosta

New member
Joined
May 3, 2012
Messages
3
Hello,

I'm thinking to improve my Edirol R4 pro replacing its standard njm2068 op amp.
Reading around I found that the Texas Instrument LM4562 could be a very good option.

Does anyone have experience modding that recorder and also what caps should I replace if needed?

Many thanks.

Emanuele
 
Thanks for the warm welcome pucho812.
Please keep in mind that posts are not Nectar points, so if you have nothing to say just don't answer so not to waste anyone time.

I was just wondering if anyone has experience with that, if not is fine anyway.
Thanks.
 
What is the problem in the current situation? Do you have problems with a high noise level or is there an other problem?
Most of the time manufacturers have their circuits well designed.
Be careful if you replace OpAmps. In some cases you have to alter the frequency compensation as well.
By omitting this, you will end up with oscillation and other problems.
But I suppose (and hope!) that you will have a good reason to make changes to the original circuit and know what you are doing!
 
Do it!
Worst case scenario you ruin your edirol, best case is you getting sounding a little clearer. I think what some people fail to realize is that modding gear while won't turn your edirol into an apogee, it is a very valid and good way of getting more fidelity out of consumer, or pro gear.

There are lots of threads about "mods" so maybe that is why some people here aren't as eager to help as maybe threads about other stuff.

But that attitude probably comes from people thinking they CAN get 1000$ performance from a modded 100$ piece of gear. Which delusions aside ain't gonna happen.

Still I modded my M-audio Delta 1010 with some better opamps, and better electrolytic capacitors a couple years ago...no going on 5-6 years now, but compared it to a stock 1010 the other day, and the modded delta preformed better. Enough better to justify the 30+ hours and 300$+ dollars it took me? Maybe not, but it was well worth the learning experience!

So I would recommend replacing the electrolytic capacitors first, because I find cheap electrolytic distortion the most offensive. It "smears" and clouds the sound (again, very general assumptions) while bad opamps, don't seem to sound as bad as bad caps.

Anyway 2 cents worth, and dig a lot yourself, look at other mods, other pieces of equipment, if your lucky you can find someone that has done the mods and can help you out, otherwise maybe not.

Also, make sure the parts are actually crappy before you go replacing stuff. Might just be other limiting factors in the design/signal chain. Usually to increase performance you want to start at what the mic "sees" and then the mic, then the pre-amp, then the A/D...etc..

Anyway you probably know a lot of this stuff, but just want help.

Best,
Abe

Also is it all surface mount stuff?
 
I'm sorry guys, I'll be more friendly from now on. 

If you want to replace your opamps go ahead, it's the style these days. might as well be in fashion. ::)

However I will point out that originally I did ask

pucho812 said:
Is there any reason why you want to replace the opamps?

Now I  have yet to get an explain what you do not like about the edirol. not all op-amps are equal and you may or may not cause more harm then good.
 
Also with its 2K$ Plus price tag, I doubt they skimped *that* much on the design, that by replacing a few parts your going to get enough sonic benefits to justify the risk and time of taking it all apart. But you never know...
 
Thanks everyone for your answers.
First of all I'm very happy with that recorder and it worth the price.
At the moment I'm feeding the R4 pro through a Sound Devices 552 and is very quiet via Line level. Now.
I've never been happy with the noise of the original hard drive going to the recording, filling them up with "mechanical" noise.
After chasing the assistance asking if they knew about that issue and if they had any solution, I've always had negative answer from them.
Now that Edirol is completely transformed in Roland, all the Edirol products are unsupported.
At some point I managed to adapt SD cards working internally instead of the hard drive finally I got rid of the annoying noise and I can now use it for field recordings.
I now just would like to have the chance to plug my mics directly to the recorder (at the moment I find inputs at mic levels a bit too noisy for very quiet environments) without external mixers, so I can abandon it overnight in the wood and keep the signal path as short as possible and not to worry too much about my kit left alone in the dark.

So said, I would like to know if someone could help me with that.
Replacing the caps is a great idea but I don't know which are goods for my purposes.
Anyone has suggestions about brands and models and shops/online shops for small quantities of smd parts in UK?
I think I got wich is the preamp stage on the pcb and having access to caps I would like to replace them all.
In the meantime I found affordable LM4562 through eBay and I'll try to replace them. If not lucky I will put the original ones back in position.

I'm not trying to have an Apogee in an Edirol, just improving the mic input noise at mic level.
 
lamacchiacosta said:
I'm not trying to have an Apogee in an Edirol, just improving the mic input noise at mic level.
That's a much better reason for modding a R4.  Got a link to a schematic of the mike i/p?

Depending on the i/p circuit ..
  • changing OPAs may not give any improvement.
  • What WILL improve mike i/p noise is using transformers with about 1:3 ratio.  Look on the Jensen site for ideas and how to match to the OPAs/circuit.  But you have to get the P48V around it.
 
lamacchiacosta said:
I'm not trying to have an Apogee in an Edirol, just improving the mic input noise at mic level.

Ah that makes sense, in retrospect, i didn't meant to put words in your mouth, just as an example of what I wish changing a few parts around would do ::)

Sounds like a fun project, I've been interested in field recording lately, now that I have a decent shotgun mic (mkh804)

Im not in the UK but I know a lot of people that are around here use this place for electronic parts :

http://uk.rs-online.com/web/

Another solution that might work (I've been toying around the idea in my head) is to build a small portable preamp, that runs on 2 9v batteries and an ina217 preamp chip. It should work fine as long as you have a source of quite 48v phantom for mics.

Also I've noticed with my mic, running it off the battery supply vs. the p48 supply it is much quiter. Now I know this is just the design of the mic and the power supply, but I can't help but think that maybe filtering the power supply in your unit might help with noise (hiss) if its using a switching power supply. or not.

Anyway good luck

 
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