Topic: Tascam DR-70D 4-channel audio recorder (Part 6)

[voltronic]

If mine weren't so nicely encased in my new SOG Tactical 6 bag, I would grab one of those instantly. K-Tek makes great quality stuff IMO

Would you mind posting a picture of your 70D in that bag?  I'm looking to upgrade to a larger bag, and haven't found one I like yet.  I'm not a fan of all of the "sound guy" type bags with the clear flap since you can't totally enclose them.

[soundsinteresting]

Activity seems low on this thread, does that mean that all problems with DR70d  including "Write Timeout" errors has been solved with v1.13 upgrade or has noone tested it with "bad" cards yet?

Did anyone that made the upgrade with input amplifiers make some measurements to  the recorder output before and after changes saying that internal noise has improved or maybe not measurable?
DR701d seems to have different input amplifiers but maybe quality is related to discrete (HDDA) input components?

[Life In Rewind]

Activity seems low on this thread, does that mean that all problems with DR70d  including "Write Timeout" errors has been solved with v1.13 upgrade or has noone tested it with "bad" cards yet?

Did anyone that made the upgrade with input amplifiers make some measurements to  the recorder output before and after changes saying that internal noise has improved or maybe not measurable?
DR701d seems to have different input amplifiers but maybe quality is related to discrete (HDDA) input components?

No - it took almost 10 months a 50 sets before I started having issues...maybe this time next year...

[2manyrocks]

The details of the performance of the mod are discussed here:  http://taperssection.com/index.php?topic=174046.0

Generally, I believe the mod made a subtle improvement if you listen carefully to the piano notes before/after the mod.  It's not a light and day difference, but I hear a subtle improvement, IMO.

[voltronic]

I think my little piano demo is a little hard to hear the differences because of the background noise of my apartment.  What I have found over using my modified deck over the long term is that while the self-noise didn't really change audibly, the quality of the treble range improved significantly as did clarity overall.  I'm not sure how much if at all you'd hear this with an amplified rock show, but I hear it in all of the choral recordings I do.  When my 70D was stock, I would absolutely prefer my FP24 > M10 chain.  Now, straight into the modded 70D wins.

I hate to use a silly audiophile trope, but the difference in my recordings before and after the mod remind me a bit of the "veil being lifted."     In all seriousness, it's sort of like with and without heavy wind screens on the mics.

The specs on the opamps used in the 701D are close to those used in the JW mod.  Whether those opamp specs or the added caps amount to anything was the subject of much discussion in the mod thread linked above if you're curious.

Bottom line for me, I'm happy to have gotten the mod and the improvement makes it the best recording chain I own for the music I record.  As always, YMMV.

[soundsinteresting]

I did try to find some of the related files to the mod, but none of the files seems to be  present at dropbox so i cannot listen to examples.
i am not convinced that it would be worth the effort for me, but congratulations for those that did find some gain doing this.

i was maybe looking for some noise improvements as this is indicated in specs for DR70 compared to DR701 as DR701 seems to have slightly lower noise floor of -124dBu compared to -120dBu of DR70.
However it also looks as DR701 has better audio performance with better linearity and lower distortion, but whether this is obtained by better input amps is not obvious.

The noise floor of DR70d is not really a problem unless you go for low sens or low noise mics in low level recordings like ambience nature recordings with NT1A's or similar but at that point it is a matter of recording silence or very low sound levels and for this DR70 is maybe not the optimum choice.
If you clamp input amps with impedances of app 150ohms and listen to the output at max gain , noise is audible but in most cases superseeded by noisy mics or head phone amps as in real life.

[Life In Rewind]

I did try to find some of the related files to the mod, but none of the files seems to be  present at dropbox so i cannot listen to examples.
i am not convinced that it would be worth the effort for me, but congratulations for those that did find some gain doing this.

i was maybe looking for some noise improvements as this is indicated in specs for DR70 compared to DR701 as DR701 seems to have slightly lower noise floor of -124dBu compared to -120dBu of DR70.
However it also looks as DR701 has better audio performance with better linearity and lower distortion, but whether this is obtained by better input amps is not obvious.

The noise floor of DR70d is not really a problem unless you go for low sens or low noise mics in low level recordings like ambience nature recordings with NT1A's or similar but at that point it is a matter of recording silence or very low sound levels and for this DR70 is maybe not the optimum choice.
If you clamp input amps with impedances of app 150ohms and listen to the output at max gain , noise is audible but in most cases superseeded by noisy mics or head phone amps as in real life.

Mod Thread Here...

http://taperssection.com/index.php?topic=174046.0

[2manyrocks]

The 701d is $599 vs $249 for the 70d at list price.  The 70d was as low as $180 last year. 

Note that there is no list of approved media for the 702d currently.  Who is to say 701d owners may experience what some TS members experienced with glitches and then Tascam released a list of approved media and later revised firmware.  IMO, I would not be an early adopter of a 701d at $599. 

As for the mod, I don't think you'd notice if you are recording rock n roll in a bar, but you might very well notice if you were recording a choir with piano.

[soundsinteresting]

I did try to find some of the related files to the mod, but none of the files seems to be  present at dropbox so i cannot listen to examples.
i am not convinced that it would be worth the effort for me, but congratulations for those that did find some gain doing this.

i was maybe looking for some noise improvements as this is indicated in specs for DR70 compared to DR701 as DR701 seems to have slightly lower noise floor of -124dBu compared to -120dBu of DR70.
However it also looks as DR701 has better audio performance with better linearity and lower distortion, but whether this is obtained by better input amps is not obvious.

The noise floor of DR70d is not really a problem unless you go for low sens or low noise mics in low level recordings like ambience nature recordings with NT1A's or similar but at that point it is a matter of recording silence or very low sound levels and for this DR70 is maybe not the optimum choice.
If you clamp input amps with impedances of app 150ohms and listen to the output at max gain , noise is audible but in most cases superseeded by noisy mics or head phone amps as in real life.

Mod Thread Here...

http://taperssection.com/index.php?topic=174046.0

Yes i know as referenced above, but the referenced links at dropbox are reported missing (empty) at my PC, so no recordings found available, could be a local problem with dropbox?

2manyrocks:
I have  no ambitions for a 701d, just curious on the difference to 70d if some crazy idea should appear :-D

[voltronic]

They're no longer in my Dropbox, I had to make room for other things and deleted them a while ago.  I can post them again when I'm back at my computer but like I said it's a very flawed comparison.

While it's not a comp, here is the best recording I've made thus far with my modded 70D:
http://taperssection.com/index.php?topic=176244.msg2175055#msg2175055

[voltronic]

Files re-uploaded and dropbox link fixed in the mod thread:

http://taperssection.com/index.php?topic=174046.msg2152868

[soundsinteresting]

Files re-uploaded and dropbox link fixed in the mod thread:

http://taperssection.com/index.php?topic=174046.msg2152868

Thankyou for the opportunity to listen to your recordings of this setup.
I tried to listen to the "raw" files numerous times but maybe I am not experienced for this. i did not succeed to distinguish the two recordings and in a blindtest i would certainly fail.
However this does not mean that a difference does not exist just that i personally am not able to recognize it in conditions met.
Having the two recordings loaded to audition i find the spectrum scanned incredible equal for both recordings except from peaks mentioned at 21.7khz and a minor difference of playing probably in area from 7-10khz, but noise and general impression are incredible equal spectrum wise.
But most important is that you are happy with your mod :-).

[voltronic]

Files re-uploaded and dropbox link fixed in the mod thread:

http://taperssection.com/index.php?topic=174046.msg2152868

Thankyou for the opportunity to listen to your recordings of this setup.
I tried to listen to the "raw" files numerous times but maybe I am not experienced for this. i did not succeed to distinguish the two recordings and in a blindtest i would certainly fail.
However this does not mean that a difference does not exist just that i personally am not able to recognize it in conditions met.
Having the two recordings loaded to audition i find the spectrum scanned incredible equal for both recordings except from peaks mentioned at 21.7khz and a minor difference of playing probably in area from 7-10khz, but noise and general impression are incredible equal spectrum wise.
But most important is that you are happy with your mod :-).

Not surprised - like I said multiple times already, it's not a good comparison and I would fail a blind test also if this were the recording being tested - so many variables it's completely invalid; I was just putting the files back because you wanted to hear them.  I've found the improvement with the mod more revealing in live choral / instrumental acoustic recording such as in the other thread I linked above.

[soundsinteresting]

I have been tampering a bit with DR70d to get an understanding of the performance of this recorder, but i get stuck with some basic understanding af level definitions (dBu)
I made some basic measurement of selfnoise for the recorder and some of my mics attached that looked ok to me.
however i tried to compare results with the same setup on another recorder (SD702) which basically should have better figures, that did also work ok.
My problem showed when i tried to compare results in Audition to get an idea of how far DR70 is from SD702.
i could not get a valid result to trust as DR70 came out far worse than I expected and with some gain indications that did not look reliable.
If DR70 is set to max gain ir should be app 63dB and doing the same with SD702 it should be app 67 dB which is a difference of app 4 dB that could be corrected for.
i tested different capsules DPA/B&K but somehow I could not get the figures to match as i had a difference of app 10dB on result.
Is it possible to compare recorders with same gain and setup and VU set for dBu (I suppose) or is this not to expected being a valid measurement?
With same gain and same transducer should it be possible to have app the same result in figures to be displayed or have i interpreted this wrong.
I load the 2 files recorded in both recorders into audition and make a visual compare that does not look reliable (to me).
What am i doing wrong?

[voltronic]

Others will be much better equipped than I to explain how to do a proper test.  What I can say for sure is that is that the HIGH+ setting on this unit is so noisy it's almost useless.  Jim Williams told me that it's the input transformers which are to blame for the high noise at high gain.  The other 3 gain ranges are plenty quiet enough to use though.  I never really go beyond the MID setting.