On Saturday night I'd just started playing Mark Ronson when it stopped after about 20 seconds. I quickly started another song and played it again in my headphones and it stopped again. A little later on the other deck, Free - Alright Now started jumping and skipping. Both were on my USB drive. I switched to the internal drive and although I had to use the USB for the odd track later on (with great trepidation), everything else went ok. Now I'm guessing the fault lies with the USB drive or the link between it and the Denon. I was thinking of running chkdisk on the said drive but would welcome any suggestions before I start tinkering.

It is possible that both tracks did not rip correctly to the hard drive.

Have you tried playing them via a PC or laptop? If you do and the same problem occurs you'll know the answer.

Doesn't hurt to defrag external HDDs especially if you've edited files or tags when using HD2500s. I had some issues with playback, all of which were cured by a defrag. I'm not saying it will cure your problem , but it won't make it worse.

Your own quick testing of trying the internal drive of the DN-HD2500 and find that it played tunes perfectly from there almost definately shows that the DN-HD2500 wasn't causing the problem - more likely the external drive, or something inbetween...

If you use an external USB hub to run the external drive and say...a USB keyboard (for even faster track searching), check that the power supply for the USB hub hadn't worked loose from the hub (making it an unpowered hub). Also, check that the external hard disk drive power supply hadn't worked loose from the back of the external hard drive either. Some hard drives, and hubs claim that external power is optional...for on-stage use, I wouldn't recommend relying on humble USB power.

Some hard drive makes/models occasionally go off and do their own agenda from time to time eg: "If external hard drive temperature is greater than xx'degrees then stop reading/writing data and just spin down until the temperature falls to just yy'degrees, then move all the heads from outside edge of data platters to inside edge of data platters and back again, recalibrate, then go back to doing any reading/writing thats being asked of you". Such recalibration sub-routines are often embedded into the external hard drives own in-built coding, same as "sleep mode" which some makes/models of hard drives coding has built-in (defeatable on some makes).

There are two sides to the "try defraging it" idea.

Firstly, some djs who use PCs or Lappys have reported that their external USB connected hard drives have become unusable/unreadable by Windows after lengthy de-fragging sessions. Indeed I recall a member of this forum reporting that they started de-fragging their lappys usb harddrive one new years eve afternoon and it was unusable that night.

However, I've been informed from Denon US that there have been no reported issues with de-fragged USB external hard drives when used on a DN-HD2500. Maybe its Windows that doesnt like external USB hard drives, maybe its the NTFS file system (The DN-HD2500 only uses the more established FAT/FAT32 file systems). The other variable is the de-fragging software being used. The original bog-standard Windows de-frag tool, with all the graphical blocks is unbelievably, incredibly slow - eg: over half a day to defrag a 500gb drive - other, Non-Microsoft de-fraggers do a much speedier job of it. The duration of the de-frag job could play a part in the overall success, bearing in mind that a drive thats spinning its way through say...30 minutes of defragging will heat up far less than a hard drive thats sweating its way through a 5 hour defrag.

Sorry to contradict but, in my experience you defrag external hard drives at your peril ... a Maxtor OneTouch II hard drive of mine was corrupted beyond repair following a casual defrag attempt, and I found several tech forum contributors had similar complaints. The theory - at that time - was that the USB drive interfaces on certain external hard drives aren't up to defrag operations. The alternative is to move/copy all files onto a separate drive (your backup drive ), clear the main drive and then copy them back to that main drive, which would effectively do the same job anyway.

Thanks to all for your comments. As with all good fault finding, I'll go through each suggestion.



Both tracks have been played before on several occasions without problem, so I would assume that they have been ripped correctly.




I don't have a powered hub, but I've managed over 50 discos without a problem and wasn't doing anything different when it happened.



It was plugged in at both ends and the LED was lit and flashing



The room wasn't any warmer than other venues I've played at and the drive sits on the table so has full ventilation.



With regard to defragging, I would tend to prefer the option of reformatting the drive and then reinstalling, as all the files on the drive are stored elsewhere.

Any other comments appreciated as I'll wait a couple of days before doing anything

I'm no expert here, but it sounds like you need to try a powered hub first, can you borrow one? The spec for USB power is quite low, not many ext hard disks work.

And surely, the OS on the hd2500 doesn't get affected by fragmented (if indeed they are) hard disks?

Do you need a special powered hub for the Denon?


If not - staples have one on offer - powered unit £7.99

Worth a punt.

Just to clarify, the external HDD has it's own power supply. The only thing attached to the hub that's unnpowered is the keyboard.

I aint that up with the denon stuff to be honest


I did have a play at bpm with the HD2500 but couldnt get on with it


Hope you get it sorted anyways

so it was working but now its showing signs of problems

Just out of interest, did you buy your ext hdd on price or quality?

the problem is with USB or the External drive not the HD2500...

I would be double checking the files on the dirve.. yes they have played before but if the dirve has a fault the files could be come damaged and then not play..

I doubt that you have anything seriously wrong with either the HDD or the controller. Of course, neither will be guaranteed to be faultless, so attempting to duplicate the circumstances again on the controller as well as a computer would seem a logical step. You may or may not be able to reproduce the 'fault', but please do keep us all posted on your progress - it sounds very intriguing!

Size and Price

interesting reading.

Anytime you use a hub with our system it MUST be powered.
To get by 50 times, I'd say you were just lucky.
We recommend using a Belkin brand powered hub for best performance.
All the best...

Don't know about you chaps, but to me gadgets that rely on external transformers don't look like they're fit for the trials of mobile work - especially ones with barrel power plugs - just another fiddly thing that rattles around in your kit, looking like they could break at any time.

Denon, can I suggest that the DN-HD2500 Mk II come with more than 2 USB peripheral sockets, so a hub isn't necessary? 4 sockets would be ideal - full time connected hard drive, pendrive + keyboard, plus an aux for random punter's mp3 player, etc.

Maybe in the meantime someone will produce a 1U rackmount integrally powered USB hub (with recessed USB sockets to help prevent accidental USB plug/pendrive breakage) and a couple of removable hard drive caddies. Anyone know the address of the patents office?

Well, for mobile guys, the transformers for a powered hub, and powered USB external drives etc, would normally be hidden (velco'd etc) inside the flightcase. On my own DN-HD2500 rig, theres a 6 way mains socket, which has the usual 19inch rack ears with which it's bolts to the inside of the flightcase. Into that plugs the transformers for the drives and such, keeping them in place.

On the plus side for external Wall-Warts (power supplies) the heat that a transformer would create is kept external to the device which they're powering, rather than adding to any internal temp. (but, I agree with you about the barrel/coaxial type power plugs - especially the interchangable ones...