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Using Alesis' HD24 as an A/D converter

Discussion in 'Pro Audio Equipment' started by Mickey S., Jan 23, 2011.

  1. Mickey S.

    Mickey S. Active Member

    Hi folks!

    Is it possible to use the HD24 just as an A/D converter and feed those optical signals into some kind of ADAT2FireWire-interface that is connected to a computer? Or will the HD24's ADAT outputs only deliver a signal when the respective track is in playback (playing back recorded stuff from the harddisk) mode?

    If this is possible what kind of ADAT2FireWire interface would you recommend? I'm looking for a 'box' that just converts from ADAT to FireWire. It doesn't have to comprise A/D or D/A converters and stuff on board.


    Thanks,

    -Mike
     
  2. TheJackAttack

    TheJackAttack Distinguished Member

    It is possible. The key is to make sure the sample rate and clock is set correctly for the destination interface. If this is an HD24 then it is not the best for conversion to 88.2k/96k. The HD24XR would be good for up to 96K though.

    Any firewire interface that accepts ADAT is almost certainly going to have AD/DA so that is a moot point. Where are you going with this idea? What is your signal path goal? The HD24XR is already a fine "field recorder" or redundant backup. I'm not sure you gain anything by trying to jack rig it into a pseudo interface.
     
  3. Mickey S.

    Mickey S. Active Member

    First, thanks a lot for this information.

    I'm only going for 24Trk/44.1kHz recordings.

    The thinking behind this is that it happened three times already that the recorder rendered the harddrive unreadable and broke that very recording ('invalid drive format' was the message that the recorder displayed the next time I used this harddisk with the same recoreder) after I did a 24-track, 44.1kHz recording session of about an hour or so. I just want to have a backup recording-'something' of the same live audio that comes from a 24 channel live console which has indeed 24 microphone XLR channels patched. So I just want to feed a PC's ADAT-I/F with the digital audio from the recorder.


    Thanks,

    -Mike
     
  4. RemyRAD

    RemyRAD Guest

    Yeah, sure, no problem using it as a 24 input A2D converter. But you're going to have to shove it into something if you're not going to record with the HD 24. So your choice is to take the optical outputs. Now, this there something else you should know, the HD 24 is not accurate at 44.1 kHz sampling but it is accurate at 48 kHz. Then there is the difference between the HD 24 & the HD 24xr. The HD 24xr which had the superior converters is no longer available. The upgrade that was available to the standard HD 24, that essentially made it the HD 24xr, are no longer available. So if you have a standard HD 24 it's certainly adequate.

    What to plug it into? The way I have mine configured, HD 24xr, the optical outputs are routed to the optical inputs to my MOTU 2408mkII/PCI 324 to a desktop computer. When I'm recording a music only project, I generally still track it 44.1 kHz but for video, I go at 48 kHz. If you want 44.1 kHz you may want to clock it from the 2408 since its 44.1 kHz clock is accurate. This will require the BNC clock output from 2408 to be sent to the BNC external clock input to the HD 24 for 44.1 kHz accuracy. Otherwise you might have timing, tuning & synchronization issues when using 44.1 kHz on the HD 24 because it's not 44.1 kHz. It's close but no cigar.

    I have numerous reasons for utilizing this kind of setup. First, because I specialize in live recording, with a network television background, I like to have redundancy. So that either means 2 HD 24's or the use of the single HD 24 with its own recording capability along with the simultaneous optical output, allows me to also record 24 tracks directly into the computer, directly to an external hard drive. The reason for this is that the HD 24 rights all of its data to a specially formatted disk drive utilizing their own "FST" disc format. Now this FST file drive must be converted either in real-time (a slow process) or by utilizing an external device that allows you to transfer one of its disk drives to your computer so that you can write your audio data to a fat 32 or NTFS formatted drive. And when you want to give your client a hard disk drive of the recording, if they don't have an HD 24, you really need to deliver to them a disk drive that is fat 32 or NTFS not FST. So taking the optical output in real time when recording & go into a computer allows me to have a 24 track back up to an NTFS hard drive already to give to the client with no further conversion necessary. Then I still have the FST-based master disk in the HD 24. That's redundancy man. But I say that was redundancy? Like I said though, the trick is to clock the HD 24 and 44.1 kHz from another clocking source if you want 44.1 kHz for CD projects. Frequently I'll just roll at 48 kHz since I know I can still obtain sample accuracy and since I frequently will do an analog mix through the old Neve. And then from the old Neve all I need is another external 2 channel USB converter to write 16 bit 44.1 kHz stereo mixes and that are also sample rate accurate to 44.1 kHz for standard CD release.

    No, you don't need to be recording anything on the machine to utilize it as a standalone 24 channel converter. The optical outputs are always active on the HD 24 so anything going into it from the analog side is immediately available at the optical outputs. You can choose whether to record on its internal drive or not. You'll have to have the machine on, in record ready with all 24 channels engaged as in ready to record. You just don't have to press the forward & record buttons which then rolls it to the HD 24 hard drive. Conversely, if your intention is to playback a 24 track recording from your computer hard drive to come out the 24 channels of analog output from the HD 24, you'll also have the utilize the HD 24's optical inputs. So using it for recording sessions & overdubs, etc., can get a little dicey in all of your optical & analog routing. You can end up with some pretty horrific feedback if you're not careful. If you're using headphones, you won't be able to hear much after that. If you're using speakers, you really didn't like those speakers anyhow did you?

    If you need further information on utilizing HD 24 you will find there is a Yahoo group devoted to that. You may also want to Google " HD 24 TOOLS ". You see, the included FST transfer software and is not as capable as the Dutch gentleman who created HD 24 tools. This is similar but much more capable software and software that can also rescue FST formatted drives that have had their headers corrupted and so can no longer be transferred to a computer since the FST software cannot read the drive any longer. HD 24 tools can! He is not associated with Alesis nor Newmark. I was fairly active on that group and I have been talking about creating a more modular off the shelf 24 track recorder. It wasn't long after discussing this possibility that the new JoeCo box was then released 2 years ago. Well, this is exactly what I was talking about and makes a lot of sense for live capture. Although the Joe Co box is not set up for any kind of overdubbed capabilities. Nope ain't going to do it. It's designed for live recording in a single 24 track pass. However, for most folks, you'll do your overdubbed sessions utilizing another interface with your computer and having already recorded 24 tracks to an external fat 32 or NTFS disk drive, whatever software you use will allow you to do the overdubs through another external interface.

    I have one of the most expensive consoles & the cheapest recorder. Where are my priorities? I think it's obvious? I'm sitting on my largest asset.
    Mx. Remy Ann David
     
  5. Mickey S.

    Mickey S. Active Member

    Wow, now that's what I call a reply to a question!!! Thank you very much! It clarifies pretty much what I still wanted to know about my HD24.

    Well, I didn't know the standard HD24 wasn't working accurately at 44.1kHz. But the 96kHz (which required the XR model or the add-on board) had never been an option to what I had in mind for this device. I just needed something to record my band's live gigs and rehearsals in order to come up with a demo CD and to rehearse where in a song might be some room for improvement so I just went for the standard model. ;o) And yes, I do know about the Yahoo group on the HD24; it wasn't until earlier this Sunday when I got to know that this existed. And, again: yes, I do know about and use the HD24 tools that the dutch gentleman wrote. It's actually my only option using my PC running Linux or Win64 (never got the FSTConnect to work with the latter one and I'm not willing using a virtual machine to run Win32 or so - that'll be overkill!!!).

    Next I was looking for a relatively cheap option that would allow me to continue using at least the HD24's A/D converters for recordings when I might run out of standard IDE/PATA harddisks and my existing ones brake (I do know MagicSound sells SATA caddies - I just ordered one the other day). An alternative solution would have been three MOTU/FireFace in order to record 24 channels simultaneously. But that would have tripled/quadroupled the price compared to getting a HD24 four years ago.

    Another option to record various channels directly would be using digital consoles like a Yamaha PM5D with those add-on cards (I belive MY16AUD DANTE) which enable for using, uhm, Dante in order to feed the data directly into a laptop's multitrack recording software. But solutions like this are way - and I do mean way - beyond my budget.

    Anyway, I think now I know where I'm at and just have to find a way how to deal with the situation.


    Thanks,

    -Mike
     
  6. TheJackAttack

    TheJackAttack Distinguished Member

    At 44.1k the FF800 will record 16 channels of ADAT and 10 channels of analog. Triple price not so much as long as you already had enough mic preamps to feed the line inputs.
     
  7. RemyRAD

    RemyRAD Guest

    The standard HD 24 is perfectly adequate as I've used my buddies, to record and mix his own band. And mostly, it's all rock 'n roll and I like it, like it, yes I do. You only need so much accuracy for rock 'n roll. After all we're all trying to get a certain kind of distortion cranking anyhow. Does it matter if it's coming from somebody else's converters which are not supposed to be as good as somebody else's converters? I think not. It's recording and mixing that really make the difference. Not equipment specifications. It doesn't matter if it sounds better to you initially. It only matters if you know how to record and mix. That's the art in the science. Science doesn't make good recordings art does.

    The bit about the parallel drives, yeah, that's an issue with the HD 24. Even though there are SATA adapters one can get for the HD 24, I don't think they have worked out all of the bugs yet on that modification. I also find issue with those removable Taiwanese hard drive trays. I've not only written extensively about that I have posted a YouTube video about permanently mounting a hard drive within the unit. This only gives you a single removable tray which I think works out better. The main drive is then a 400 GB Seagate which is more than adequate for any single project. Then you have your removable " work drive". This means the master drives integrity is never compromised by removal or re-connections. It's also silicone rubber isolated and is afforded more air circulating convection style cooling. Then all you really ever need is 2 parallel drives for the unit. 1 permanently mounted inside and 1 in the removable tray. You don't need any other parallel drives. All of your clients and/or 24 track backups are easily transferred to external USB/FireWire SATA storage & distribution drives. That's a beautiful way to go and now, you can even incorporate ProTools 9 with your HD 24. How cool is that?! Of course all of your DSP RTAS plug-ins are still dependent upon your CPU instead of dedicated DSP farm cards. Especially, if you want an overabundance of real-time functions.

    Hey! Have they solved that real-time play out function with ProTools 9? Will it render multitrack mixes faster than playing them in real time?? Like Adobe Audition 1.5 or better & Sony Vegas 4.0 or better, the rest?? I hate that about ProTools. I don't care of it is real time. I like faster than real-time. And that's what I want once I know that's what I want and I want it quickly. Quickly now! Schnell Schnell! Das boot. Some Hefe' beer maybe?

    I'm a Toneschiester Raven maven (since I also come from Baltimore. That's not supposed to make any sense)
    Mx. Remy Ann David
     
  8. Davedog

    Davedog Distinguished Member

    I run mine @24/48 and have never experienced a clock issue. You will need to pay strict attention to the monitoring position when youre doing it this way. It will kill ya when it loops....Analog in, digital out....
     
  9. Mickey S.

    Mickey S. Active Member

    Alright, one more time on the 44.1kHz-clock-thing: Could it be that screwing up an approx. 1-hour-worth-of-recording might be due to the not-so-accurate device's operation at 44.1kHz? Just an idea... If so I would immediately switch to 48kHz. I'd only had to resample stuff for bringing it onto a CD then. How much would I actually have to sacrifice when resampling from 48kHz down to 44.1kHz? I'm not talking about what lower sampling rates imply, this is all clear to me. I just mean, is resampled material far worse than stuff sampled directly at 44.1kHz?


    Thanks,

    -Mike
     
  10. Boswell

    Boswell Moderator Distinguished Member

    As others have indicated, just set the HD24 input monitoring to "Auto" and check that the channel mode list on Utility page 11 is all set to "Analog" and you will get 3 lightpipes of ADAT out comprising digital data from all the HD24 analog inputs. It does not need hard drives to be spun up or even inserted.

    This will work at 44.1KHz and 48KHz using a standard HD24. If you had an HD24XR, you would be able to run that combination, or alternatively 12 analog input channels at 88.2/96 KHz. Both modes of operation require 3 ADAT lightpipes to carry the digital output data. I would run the HD24/XR from external BNC wordclock at least at 44.1/88.2 KHz, as the internal clock is stable but slightly inaccurate, as the others have said. Be aware that the full-scale analog input level on the HD24 and HD24XR is +19dBu.

    For interfacing the HD24 ADAT outputs to FireWire, try the Presonus FireStudio Lightpipe or the M-Audio ProFire Lightbridge (both are 4 ADAT/32-channel units). If you only have the stock HD24 and not the HD24XR, I would suggest getting an RME FireFace800 and taking 2 lightpipes (16 channels) from the HD24 ADAT outputs to the FF800 ADAT inputs, and use the the FF800 for the main (important) analog input channels. This would be either via 4 external choice pre-amps and the 4 pre-amps in the FF800 or 8 via external pre-amps.
     
  11. Mickey S.

    Mickey S. Active Member

    Would it also be possible to combine two FF800 to appear as one 32 channel input to a multitrack software on the computer the FireFaces attach to? If I'm into spending on such a thing then why not going for a 100% solution anyway?


    Thanks,

    -Mike
     
  12. TheJackAttack

    TheJackAttack Distinguished Member

    Up to three FF800 can be daisy chained via firewire800 cables. That is what I utilize as my main interface and then run ADAT out to my HD24xr. For what it's worth, there are EC2 upgrade kits still available online with the better converters.

    You should not be having drive failures on the machine however. These things are pretty bulletproof providing the hard drive itself is in good shape and the caps providing the drive power are good. You may want to take it to someone like Boswell who can service the machine. It will cost money sure, but other than a Mackie SDR I've never found anything else as capable. I'm going to probably purchase a JoeCo w/ADAT in the future simply because I was stupid enough to sell my second HD24xr a few years ago and I hate not having redundancy.
     
  13. TheJackAttack

    TheJackAttack Distinguished Member

    Inre resampling, the best way in my opinion is to use two devices. When I am done mixing, I run each track out into a summing mixer from the Fireface and then redigitize in the HD24xr at my target sample rate.
     
  14. Boswell

    Boswell Moderator Distinguished Member

    Just to reinforce Jack's point: concurrent use of more than one FF800 needs a FireWire 800 port on the computer and not FireWire 400.

    Where is this HD24 located? I do carry out servicing on them in the EU area, but customs procedures make it a pain for units located outside the EU. Also, I'm usually careful not to advertise for business on a forum like this.
     
  15. Mickey S.

    Mickey S. Active Member

    Well it's not a drive failure like there are bad sectors and such. It happened three times so far all with different drives (which worked and still work fine), even the disk that shipped with the recorder (this 80GB one). Upon inspection using HD24Tools it seemed the data were all wrong recorded; it spit out noise as if you would listen to a CD ROM's data track on ancient CD players. I suspect that the error that falsified the audio data also impacted the drive's header data when they were updated after that very recording ended. I have been successful in recovering all the data that were on the drive before the bogus recording. Only the drive showed 'Invalid Format' and the broken recording was in fact 'digital' noise. Don't know how to put this in better words. It only happens to recordings that last about an hour.

    And, yes, I'm in the EU (Germany).


    Thanks,

    -Mike
     
  16. Boswell

    Boswell Moderator Distinguished Member

    The bad songs: (1) how many tracks in these songs? (2) do you mean you get a problem if a song lasts for an hour or more, or is there just a time period around 1 hour that gives this problem? (3) what version of firmware is in your HD24?
     
  17. RemyRAD

    RemyRAD Guest

    So Boswell, you consider the stock HD 24 to be so substandard that one shouldn't use its stock onboard converters? It's no worse than the converters in earlier generation digital multitrack recorders. They're perfectly adequate that are just about perfect enough to record just about anything. They probably don't offer their EC 2 upgrade anymore because everything has been improved upon and they know the stock HD 24 is perfectly adequate. Is it sonically brilliant? Probably not for 1500 US smackers and if one is going to blow the cash just to give it a better front end, why bother? In that respect, the TASCAM 48 track recorder might be equivalent in cost to an HD 24 with an RME interface. This all just to avoid the HD 24 converters? Sure, that PreSonus digital mixer is fine and with that, all you need is a laptop instead of an HD 24 since it is a combination mixer & recorder without the disk drive being internal. So just take the FireWire out to a FireWire input on a laptop and no need for an HD 24. And I thought my answers were strange. But knowing how good you are, I figured you just tossed back a couple of pints before your post? Or does the pursuit of sonic perfection transcend all engineering technique? I mean the guy just wants to make some demo rock 'n roll recordings and you need sonic perfection for that? I hope not. I'm just talking about making sure he can "Gitter Done".

    Yeah about that maximum input +19 DBu rating on the input side of the many permutations of the HD 24 recorder. Almost idiotic for me to use my Neve with it, given its headroom to almost +30 DBm output, into 600 ohms. So I guess I should just rewire my output transformers to step down or just use a cheap console that only has output capabilities to +18 DBu? Of course not. Of course the originating poster wasn't inquiring about input level capabilities or the lack thereof. Really, not sure why the dude doesn't want to use the internal disk drives on the HD 24?

    I mean how many parallel drives does anyone need these days? You don't take out the FST drive in HD 24's and hand them directly to clients. So you only need a minimum amount of drives to be used for your own purposes, for the life of the recorder. You do need, however, to transfer those FST drives through your computer, through their FireWire accessory adapter or utilizing the identical Taiwanese Brand tray, in your desktop running HD 24 TOOLS. But you still want to hand your clients compatible playback drives for their purposes. And that means not handing them your FST formatted drives. This means that you need to be handing them a fat 32 or NTFS drive. So you'll still have to hand them an external USB and/or FireWire hard drive in the fat 32 or NTFS, anyhow. Otherwise the whole argument about parallel drives, unavailability is really moot.

    You only need 2 parallel drives for the life of the machine.
    Mx. Remy Ann David
     
  18. Mickey S.

    Mickey S. Active Member

    @Boswell: The bad songs were all 44.1kHz, 24track. It doesn't happen all the times but when it happens it is 'triggered' by a recording that lasts about an hour or so (55 minutes to 63 minutes time, well, three times, so far). Not sure about the firmware version but it is the latest one available from Alesis' website; must be rev 1.20 then.

    @RemyRAD: I _do_ want to use the internal disk drives but as long as there is a minimum chance for the recorder to blow an important recording session (we usually have set lengths of about an hour time) I just wanna have redundancy in the setup. So, basically, an external USB or firewire 'soundcard' (one may call such a thing an audio-interface of some kind) just featuring 3 ADAT-I/O would be perfectly sufficient to have my laptop hooked up as a second recorder. This also gives me the chance to do a recording just in case the harddisks won't mount. I did experience this as well already: the HD24's mount progress indicator went up to 73% and then slooooowly up to 96% where it hovered for quite a while only to initiate unmount procedure right thereafter and telling me there was an error mounting the drive (it ranged from 'data integrity check'- to 'drive reset failed'-error or whatever it was). But a little later remounting the same drive seem to work fine. But I can't always wait for the device to warm up as it appears. And, yes, I made sure the caddy was fully inserted an its lid closed. ;o)

    I have also seen that one particular harddisk seems to work quite well in the left drive bay but it has problems being operated in the right bay. Another disk showed the other-way-'round behavior. I have also swapped drives around my caddies. Didn't change anything. For some disks these symptoms are persistant over the entire session time for others this depends on how far the recorder has come warming up.

    I'll also check on hints that folks have come up with like adding a washer to the caddy's connector screws so that it extends a little more out to the caddy's back in order to make sure the connection is well established. Maybe this is gonna fix all the problems. I only got to know about it just recently.

    I know this all must sound pretty strange but it is really the way I have described it. It's only about the harddisk operation (well, that's the device's main feature) everything else is just fine. No lock-ups and such, it pretty much runs all the time as soon as I power up my side rack... ;o)


    Thanks,

    -Mike
     
  19. Boswell

    Boswell Moderator Distinguished Member

    Well, this is posted in the Professional forum, and so contributers here should be striving for the best standards available within their budgets. There is a marked sonic difference between the analog converters in the Alesis HD24 and those in the HD24XR, and we should be guiding people to consider the better-sounding product. For users that already have the stock HD24, there are often ways of choosing and configuring the other system components to get the best advantage from it once the whole picture is clear.

    That said, the Wavefront converters in the standard HD24 (also used in the much-derided ADA8000) give a good account of themselves, and I certainly used them for a year or two when the HD24 first came out. It was not until later that I heard what a difference the XR version made, and upgraded my units. Sadly, Alesis has officially discontinued the EC-2 upgrade kit, although it's still featured on their website and various retailers such as Musician's Friend and Music123 claim to have them in stock.
     
  20. Mickey S.

    Mickey S. Active Member

    JFYI: I got my brand new unit in first half 2007. Don't think it was manufactured ages before I got it from my distributor and I don't know either if this says something about the quality of the converters used in this particular unit. Anyway, it's not that I don't like the quality that was recorded actually - it's just so that writing data to the disk obviously fails at times and renders the drive unusable the way I have outlined earlier.


    Thanks,

    -Mike
     

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