Topic: TASCAM DR-680 portable 8-track #6

[H₂O]

Anybody use metal film caps instead of electrolytic caps?

[florian.ardelean]

So if I understand correctly...the capacitor mod is to reduce noise when using phantom power? Can somebody indicate when the noise occurs? Only with certain mics? True condensers? Electrets? Dynamics?

The extra noise occurs only with *some* condenser mics. I saved the article describing which (I thing it was just older mic models? Or mics that take more current? can't recall. Will edit the post if and when I find the link)

EDIT: Here is the original post: http://www.audiomastersforum.net/amforum/index.php/topic,8551.0.html

Dynamics don't care much about P48 if they're properly wired so it wouldn't make a dfference. You can fry electrets if you apply P48 without going through a step-down PIP adapter. But you can use the internal preamps And if you would, then the P48 problem would likely turn up.

Here's a nice tech review of the noise floor of the original "stock" DR680:
http://www.lindos.co.uk/index.php?page=test_and_measurement&subpage=SOURCE=Results&subsubpage=/FlexiData/Results/files/filename/399/res.html


By the way, does anybody still have the service manual and schematic? Would love a drobox link if possible.. There is something uploaded in the "manuals" sections but due to size constaints it is cut into small pieces and it seems to be missing some parts.

[fsulloway]

Where does everyone set there mix levels for independent channels and stereo mix too??

Todd

I never record the stereo mix. Chances that I get the mix perfect at the show is close to none so I just mix at home.

[Gutbucket]

I typically  leave the stereo mix at 100% and adjust the individual channel mix levels to where ever they need to be.

[florian.ardelean]

Also about battery power i build a power supply myself. Can say that its checked for more than a 6 months of use and its very good and stable. No problem with overheating and its very efficent.

Hello

Did you put the module inside the 680? Did it fit OK? Did you do any other modifications to the existing power supply?

Thank you.

[tomuo]

So if I understand correctly...the capacitor mod is to reduce noise when using phantom power? Can somebody indicate when the noise occurs? Only with certain mics? True condensers? Electrets? Dynamics?

The extra noise occurs only with *some* condenser mics. I saved the article describing which (I thing it was just older mic models? Or mics that take more current? can't recall. Will edit the post if and when I find the link)

EDIT: Here is the original post: http://www.audiomastersforum.net/amforum/index.php/topic,8551.0.html

Dynamics don't care much about P48 if they're properly wired so it wouldn't make a dfference. You can fry electrets if you apply P48 without going through a step-down PIP adapter. But you can use the internal preamps And if you would, then the P48 problem would likely turn up.

mkII has larger caps for 48V smoothing. (4.7uF instead of 1uF)

By the way, does anybody still have the service manual and schematic? Would love a drobox link if possible.. There is something uploaded in the "manuals" sections but due to size constaints it is cut into small pieces and it seems to be missing some parts.

mkI Service Manual 3493KB, Schematics 808KB.    PM me your email address.

Tom.

[lukpac]

The extra noise occurs only with *some* condenser mics. I saved the article describing which (I thing it was just older mic models? Or mics that take more current? can't recall. Will edit the post if and when I find the link)

EDIT: Here is the original post: http://www.audiomastersforum.net/amforum/index.php/topic,8551.0.html

Dynamics don't care much about P48 if they're properly wired so it wouldn't make a dfference. You can fry electrets if you apply P48 without going through a step-down PIP adapter. But you can use the internal preamps And if you would, then the P48 problem would likely turn up.

Here's a nice tech review of the noise floor of the original "stock" DR680:
http://www.lindos.co.uk/index.php?page=test_and_measurement&subpage=SOURCE=Results&subsubpage=/FlexiData/Results/files/filename/399/res.html


By the way, does anybody still have the service manual and schematic? Would love a drobox link if possible.. There is something uploaded in the "manuals" sections but due to size constaints it is cut into small pieces and it seems to be missing some parts.

Thanks for the link. Seems to be a quirk with the 680 combined with quirks in certain mics.

BTW, by "electret" I meant mics that are marketed as standard condensers but are permanently charged and require phantom. Of course some of those can be run via PIP if the phantom adapter is separate and can be removed.

Also, while I haven't experienced the noise issue with my 680, I *did* notice a quirk. I got a pair of Rode M5s, and I was having issues with hum when the 680 was plugged in to AC. Touch the grille on the M5s and there would be tons of hum, unless you also touched a grounding point on the 680. It turned out the grille wasn't grounded. But that was *not* an issue with any of my other interfaces. Clearly there was some difference with how the 680 handled grounding. Regardless, I sent my mics back and got new ones that have the grilles properly grounded, and hum is no longer an issue.

[Chuck]

So if I understand correctly...the capacitor mod is to reduce noise when using phantom power? Can somebody indicate when the noise occurs? Only with certain mics? True condensers? Electrets? Dynamics?

The extra noise occurs only with *some* condenser mics. I saved the article describing which (I thing it was just older mic models? Or mics that take more current? can't recall. Will edit the post if and when I find the link)

EDIT: Here is the original post: http://www.audiomastersforum.net/amforum/index.php/topic,8551.0.html

Dynamics don't care much about P48 if they're properly wired so it wouldn't make a dfference. You can fry electrets if you apply P48 without going through a step-down PIP adapter. But you can use the internal preamps And if you would, then the P48 problem would likely turn up.

mkII has larger caps for 48V smoothing. (4.7uF instead of 1uF)

By the way, does anybody still have the service manual and schematic? Would love a drobox link if possible.. There is something uploaded in the "manuals" sections but due to size constaints it is cut into small pieces and it seems to be missing some parts.

mkI Service Manual 3493KB, Schematics 808KB.    PM me your email address.

Tom.

Tom:

That's so cool that you'll provide schematics! PM sent!

I wonder if you guys have figured out why some of the first gen DR-680's overheated and killed the power supply. I've had three of them and mine is out of warranty. But, I'd like to make a circuit change to fix that overheating problem. Other than that, I love mine. I stuck with the DR-680 even though my first two died. It has all the features I need. I haven't found anything i like better for 6-8 channel recording in the field yet.

[2manyrocks]

Why not buy a MKii that is already factory modded and use the 680 for those instances where more channels are needed via the cascade function? 

[Chuck]

Why not buy a MKii that is already factory modded and use the 680 for those instances where more channels are needed via the cascade function?

I will probably do that.

[Life In Rewind]

So what are the prospects for repair of broken 680s?

I BO'ed that broken one from ebay last week - should be here before the weekend.

[PiotrSzmidt]

Also about battery power i build a power supply myself. Can say that its checked for more than a 6 months of use and its very good and stable. No problem with overheating and its very efficent.

Hello

Did you put the module inside the 680? Did it fit OK? Did you do any other modifications to the existing power supply?

Thank you.

nope, i didn't put battery inside. A did a battery pack external, connected by plug to the 12v connector on the side. This way I also made another cable plug to powet up my Saffire Focusrite 26 PRO for additional preamps that im sending to Tascam 7-8 track by SPDIF if needed.

[PiotrSzmidt]

mkII has larger caps for 48V smoothing. (4.7uF instead of 1uF)

That is exacly what i did.

[connloyalist]

I did some testing tonight with phantom power noise and difference between hi-lo gain.

Test setup was this:
mic -> Radial ProMS2 "direct 1" -> DR680 channel 1 +P48.
Radial ProMS2 "direct 2" -> DR680 channel 4.
Channel 1+4 = left and right of stereo mix. Direct 2 on the ProMS2 is transformer isolated from the direct 1 that carries the phantom power.

The idea was that if there is a difference between a channel with and without phantom power in terms of noise this test ought to show it. If I am making a mistake in my reasoning, feel free to let me know.

Mics tested: Shure KSM141 cardioid and omni, Rode NT5 omni capsule, Rode NT4 MJE-384K capsule, AT4081, Advanced Audio CM1084 (cardioid) in Bright and Vintage settings.

Result: I could not prove that there is any noise difference between the phantom and non-phantom channels. I did see on most mics a distinct hump around 100Hz on all mics except the AT4081. Perhaps due to environmental noise that the figure 8 ribbon blocks out.

Perhaps when one channel has phantom power all channels suffer the same amount of noise? Or none of the tested mics suffer from this problem, as I understand it varies from one mic to the next.

A second thing I tested was the suggestion that switching from low +15 to high -8 (for example) would make a difference in noise. Here I can say that yes, there is a noticeable difference. On most mics the dfference started around 1000Hz and widened to around 2~4 dB at 10KHz. So in a quiet section of the recording (me not saying anything in my quiet living room) the low +15 channel might be at -114 dB, the high -8 channel would be at -116dB at 10KHz.

The biggest difference was with the CM1084 in vintage setting, Low +20 and High -3. There the difference at 10Khz widened out to around 8dB.

Regards, Christine

[lukpac]

Thanks for that Christine. I've never done a measurement of the LOW/HIGH noise difference, but it was very audible, to the point that I'm slightly embarrassed at the (thankfully one) recording I made with the switches set to LOW. I wonder if that will still be an issue with the mkII.