Tascam DR-70D - modification discussion

[voltronic]

Anyone want to take a stab at the before / after files I posted?  I know what I do and don't hear, but would like other opinions.

[groovon]

Anyone want to take a stab at the before / after files I posted?  I know what I do and don't hear, but would like other opinions.

I have only my Sony MDR-V6s right now, but I'll take a stab at it...

Dave

[voltronic]

SMT is actually easier to rework once you learn it.  You can simply blow away components with a hot air gun, much less risk of lifting traces.  But you do need a hot air gun and a good soldering iron with a reasonably small, temperature controlled tip.

That's surprising to hear - I was always told that SMT was much more difficult, and that it's harder to find people with the skills to do it by hand. 

I worked a summer job for a couple years in college at an ISO 9001 facility in Woodstock with a lot of military and aerospace contracts.  Out of about a dozen techs doing electronic assembly on the floor, only two were certified for SMT and they wound up working on the most sensitive equipment.  When I asked the supervisors why they didn't use the robotic SMT machines, the answer was that they found the reliability rate was much better with hand assembly which made it worth it for them to put people through the specialized training.

[groovon]

Anyone want to take a stab at the before / after files I posted?  I know what I do and don't hear, but would like other opinions.

OK, I went back and forth a few times. I wouldn't even make a small bet on it, but *just possibly* there's a slight increase in Mid/HF detail in 'B'. I really hesitate to say it though. I'll have another listen sometime.

To be honest I found that both sound somewhat 'veiled' for some reason (and of course there's that hum in the L channel(?) Nice playing though 

(edit) Had another listen. I suspect any audible difference between A and B is more likely subtle variations in playing technique than anything else.

Dave

[voltronic]

Anyone want to take a stab at the before / after files I posted?  I know what I do and don't hear, but would like other opinions.

OK, I went back and forth a few times. I wouldn't even make a small bet on it, but *just possibly* there's a slight increase in Mid/HF detail in 'B'. I really hesitate to say it though. I'll have another listen sometime.

To be honest I found that both sound somewhat 'veiled' for some reason (and of course there's that hum in the L channel(?) Nice playing though 

(edit) Had another listen. I suspect any audible difference between A and B is more likely subtle variations in playing technique than anything else.

Dave

FWIW, I had a hard time hearing the difference on my headphones, but on my monitors it's much easier.  The hum is the DVR hard drive - the mic mount was clamped to my steel TV stand.  Should have thought to unplug it in the first recording, but since I didn't, I left it going for the second recording also.  The "veiled" sound you're hearing in both is because it's an upright piano against a wall.  Again, I don't think this was a great test, but it's what people were asking for, and it's what I could control myself.

Not saying if you guessed right or not; I'll wait for more people to weigh in first.

[groovon]

Anyone want to take a stab at the before / after files I posted?  I know what I do and don't hear, but would like other opinions.

OK, I went back and forth a few times. I wouldn't even make a small bet on it, but *just possibly* there's a slight increase in Mid/HF detail in 'B'. I really hesitate to say it though. I'll have another listen sometime.

To be honest I found that both sound somewhat 'veiled' for some reason (and of course there's that hum in the L channel(?) Nice playing though 

(edit) Had another listen. I suspect any audible difference between A and B is more likely subtle variations in playing technique than anything else.

Dave

FWIW, I had a hard time hearing the difference on my headphones, but on my monitors it's much easier.  The hum is the DVR hard drive - the mic mount was clamped to my steel TV stand.  Should have thought to unplug it in the first recording, but since I didn't, I left it going for the second recording also.  The "veiled" sound you're hearing in both is because it's an upright piano against a wall.  Again, I don't think this was a great test, but it's what people were asking for, and it's what I could control myself.

Not saying if you guessed right or not; I'll wait for more people to weigh in first.

I'm also 'guessing' any difference between tracks detectable from this recording is from something other the electronics. Of course, I may be biased 

Dave

[aaronji]

(edit) Had another listen. I suspect any audible difference between A and B is more likely subtle variations in playing technique than anything else.

Me too.  Taking a wild stab, though, I'll guess B is the mod, based on the faster tempo (new gear excitement and all)...

[2manyrocks]

What kind of hot air gun is needed for this?  Or is it so expensive that it's not worth it for this mod?

[vwmule]

So, essentially, the mod is not worth the hassle? I've always been amused by the obsession with mods that have little to no real effect. That's not a slam on those who try; that's a cool part of this community.

[2manyrocks]

Is the chipquik smd removal kit a lesser cost option or is a hot air rework station like this essential?  Hate to spend $149 on a station but hate to wreck my recorder.

[voltronic]

Is the chipquik smd removal kit a lesser cost option or is a hot air rework station like this essential?  Hate to spend $149 on a station but hate to wreck my recorder.

If you're having to invest anywhere near that much in equipment, you're better off paying a professional who already has said equipment, regardless of how easy it may be do yourself.  I paid less than that for parts, labor, and shipping both ways.  Besides that, if you're not 100% confident in your ability to do this yourself, then you shouldn't do it.  Just my 2 cents.

Since my piano recordings aren't getting many listens it seems, I'd like to try the "pillow test" described by Jon a little while ago.  You've got a set of CM3s - would you mind being the "before" sample?  We can discuss specifics over PM to make this as close as possible.  I can confirm that gain levels are exactly the same post-mod.

[2manyrocks]

PM me with your plan. 

[2manyrocks]

Sort of reminds me of Clint Eastwood saying, ...."do you feel lucky, punk?"   

Jumping back to the question of measuring the stock v. modded unit, is there a way of accurately measuring them by inserting a 150 resistor in an xlr shell, recording to a SDHC card  and then using software like izotope, voxengo, bluecat frequency analyst or does this require an expensive spectrum analyzer? 

[voltronic]

Sort of reminds me of Clint Eastwood saying, ...."do you feel lucky, punk?"   

Jumping back to the question of measuring the stock v. modded unit, is there a way of accurately measuring them by inserting a 150 resistor in an xlr shell, recording to a SDHC card  and then using software like izotope, voxengo, bluecat frequency analyst or does this require an expensive spectrum analyzer?

I have RX, and if you look in my dropbox folder, I included screenshots of each file's spectrogram, along with the Waveform Statistics.  There's a Spectrum Analyzer function - I can post those as well.

[2manyrocks]

Folks... it's time to listen carefully on good headphones to the A v. B samples posted at the top of the thread if you're really interested in the results of the mod.