Let's Get Technical -- The Gemini SDJ-4000

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It's time for another in-depth technical review -- In this case, the Gemini SDJ-4000 Stand Alone DJ Player and Mixer.

First, some disclaimers apply:
1. My example of the Gemini SDJ-4000 was purchased from eBay as a non-working, for parts or repair. The seller clearly stated: "PLEASE DO NOT PURCHASE THIS ITEM in hopes of potentially receiving a fully functioning unit. This listing is meant for buyers knowledgeable in fixing this item or plans to use for parts." --- and that is exactly what I did. The unit has been repaired and updated to the latest firmware. I am 100% confident that what I am reporting in this thread is based on the correct functioning of this device, and not any previous problem (except as indicated) with the particular unit I now have.
2. I will compare this unit to a number of other devices, including what I call the Poor Man's Go DJ, which is a device I constructed from various components and modules. While it is mostly hobbled together from completed sub-assemblies that I neither built or designed, I do consider the completed Poor Man's Go DJ to be my own creation, and therefore I may harbor a bias toward it, when in reality, it is not a ready-for-market product. None the less specific details and functionality is accurate as I report it in this thread.


Overview:
The Gemini SDJ-4000 is (or was, as it now seems to be discontinued) a Stand Alone DJ player and mixer similar to numerous other devices mentioned in these forums -- Particularly in the Poor Man's Go DJ thread.

I am providing this thread as a Guide for those that may be considering purchasing a used or old stock one, or people like myself that find themselves repairing one.

I will note that Gemini does list their DJ equipment separately from "Professional" equipment; however, I do not know too many people that buy a device like the SDJ-4000, and then use alone in their bedrooms or living rooms. This device is made for Gigging, and I and others get paid for these gigs most of the time, and thus are professionals. By separating DJ Products from Professional Products, I wonder if Gemini is using "weasel words" or already trying to level set expectations.

To save innocent electrons (and time), I'll keep this review to simple Pro's and Con's (with a little narrative):

Cons:

• First off the Gemini SDJ-4000 is big -- Really big. It's over 26 inches wide. It's actually wider than my Samson 12 channel professional mixer. This wouldn't be so bad if I could have just the Gemini SDJ-4000 on my DJ table. It's clearly easier than taking/setting up the Samson mixer and a Media/DJ player, and with 4 line inputs, and 2 mic inputs, this should be possible for most for the types of gigs I do; however, as we will see, this leaves a whole lot of audio functionality behind.

  

  Size comparison of the SDJ-4000 -- Poor Mans Go DJ - Monster Go DJ.

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• So about those Microphone Inputs: Mic 1 input has only a 1/4" TRS (Phone) connector. Mic 2 has a combined TRS and XLR connector. How many cents did they save by not including another combined connector and the Op Amp to handle a second balanced input? I will admit that unless a customer/venue requests otherwise, this is exactly how I am normally set up. I have a condenser Mic (fortunately with an internal battery, since there is no Phantom Power) on Input 1 with a 1/4" plug as my "House" mike , and a balanced connection (XLR) from my wireless Mic receiver on Input 2; However, there are other problems with the Mic inputs.
• In addition to the "bare minimum" connectors, the functionality of the Mic inputs are extremely basic. There are only "Volume" and High and Low tone controls for each Mic. First off, I'm going to pick on Gemini for using the term "Volume" for what is actually a Gain. Volume refers essentially to Sound Pressure Level (the Volume of air moved by the speakers). I'm not sure if the designers at Gemini don't know this or they think their customers don't know this. In addition, High and Low tone controls alone are wholly inadequate for speech, which is primarily around the mid range of the audio spectrum. Asking for a compressor circuit may be unreasonable for a device like this, but I'd like 3 equalization bands at the bare minimum. None of the effects settings/controls can be applied to the Mics, and Mics can't be sent to the other 2 input channels. There are also no indicators at all on the Mic inputs -- Not even a peak clip LED.
  Taken together -- All this means that if you are doing any kind of professional live sound, you'll still need to take along a more capable mixer or sound processor.
• Here's a pretty serious and obvious software bug: I was actually surprised at the fact that it displayed a directory of songs with Cyrillic (Russian) characters correctly - Uh -- Until I selected that directory. I then got garbaged file names. Not even the numerical track numbers were correct, so selecting a specific song can only be done by counting files from the top of the directory. The bug was present in the Firmware version that was on the device when I received it (1.4.something as I recall) and in the latest 1.5, which I loaded to specifically see if this had been fixed.)

  

  Cyrillic File/Track Names display Correctly Here

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  Cyrillic File/Track Names do not display Correctly Here

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  I should say that the files do load and play, but on the main player screen the name of the track is also nothing but garbaged characters. I also want to say that the actual Monster Go DJ, which is at least a decade older, handles these same file/track names correctly in both the directory listing and on the player screen, as do the Chinese player modules that are installed in the Poor Man's Go DJ. Hey, Gemini... There's this thing called Software Testing.
• In the thread about the Poor Man's Go DJ, I test compatibility with lossless FLAC files. The Chinese player modules that are currently installed in the Poor Man's Go DJ support high bitrate Lossless FLAC files without difficulty. Those modules cost $18 each. The $1000 SDJ-4000 does not support FLAC files. (Neither does the Real Go DJ, or many other DJ Player/Mixers.) There is no information in the Users Manual about formats/bit rates are supported as music files.
• Again, I may be biased towards the Media Players and analog tone boards I selected for the Poor Man's Go DJ, but the SDJ-4000 just doesn't seem to sound all that great. Yes, it will send plenty of clean audio to an amplifier or powered speakers -- including plenty of bass if you crank on the "Low" pot -- but it just doesn't seem to have any remarkable depth/crispness. Want to refute me by showing the the frequency response specifications in the User Manual? -- Uh -- There are no specifications at all on the Gemini website or in the User Manual. If you can't say something nice...
• Here's another pretty significant issue -- It doesn't actually have a waveform display. The waveforms are generated by separate PC software (V-CASE), and copied to the USB drive used in the SDJ-4000. If the SDJ-4000 is truly used stand-alone, it will not display waveforms or album art when a track is playing. Buyer Beware. It still does seem to processes the files on it's own to some extent. In the browse mode, files that are not pre-processed with the V-CASE software are displayed in an almost unreadable dark red on black (as seen above). After some time, the filenames turn a far more readable white, and additional information is added such as BPM (Beets Per Minute). But wait -- there's more (Problems). The V-CASE software is only available for Windows and Mac. While I'm sure it will run fine under Linux/Wine, when I browse to https://geminisound.com/products/v-case using Firefox on Linux, there is no download link for any platform. See more about the V-CASE software below.
• I may discuss more of the internal circuitry of the SDJ-4000 in a subsequent reply, but the Main Power supply does not impress. It's very basic, but provides +/-18VDC, +5VDC, and +3.3VDC. It's not an enclosed module, but it is covered by a simple "tin" (steel) shield. The only circuit protection is from a small fuse soldered to the power supply board. The power switch is in the AC line, and fully shuts off all power when switched off.

Pros:

• Actual Finned Aluminum Heatsink on the processor board. This is (hopefully) indicative that this unit has a little more processor power than some units in it's segment of the market. While I have noticed hesitation and pauses while scrolling through directories, overall, it is responsive and smooth.
• Despite the above comments about the internal power supply being rather basic, the fact that it has an internal power supply is a very good feature. There are no batteries to worry about, and "wall warts", with their skinny wires and flimsy coaxial power plugs, have no place in professional audio. The SDJ-4000 uses a standard IEC power connector and the appropriate power cord for your country. Based on markings on the power supply, tt supports 100-240VAC operation.
• In my Technical review of the Mackie DLZ Creator, I mention that the unit has very little clearance between the bottom of the unit and the table or surface that it is placed on. Free airflow into the bottom of a convection/free air flow cooled unit is very important. Gemini at least gets this correct with large feet that elevate the unit sufficiently to allow ample air flow into numerous large cut-outs in the bottom. While there is no specific convection path (no exits near the top), at least they have allowed for some airflow.
• Separately settable output level range as High, Medium and Low -- While technically incorrect (all VU meters should be at least loosely indicate the actual level relative to nominal line level), being able to adjust the output level separately allows the Master VU Meters to indicate a relative level no mater the gain or power of the rest of the audio chain,
• In other threads, I have complained about very poor VU meters on similar equipment. The SDJ-4000 has 16 segment meters on each of the 4 input channels, and 10 segments on the stereo master VU meters.
• Balanced main outputs (in addition to RCA Master outputs) -- At least they didn't skimp on this. This is especially important for those using powered speakers, as the speakers may be quite a distance away, and RCA cables are wholly inadequate for sending Line Level audio any distance.
• All sliders/rotary pots and encoders feel as they should -- far better than, for example, my Stanton SCS.4DJ. The overall construction is also much better than the Stanton SCS.4DJ. The SDJ-4000 is still all plastic, but it is much thicker plastic than the very actually brittle feeling Stanton SCS.4DJ.

Up Next: SDJ-4000 internal pictures.

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Gemini SDJ-4000 Stand Alone DJ Player and Mixer

Part II -- Disassembly and Internal

So as mentioned at the top of this thread, the software on the Gemini SDJ-4000 isn't particularly elegant. The software on the decade-old Monster Go DJ is far more sophisticated and elegant looking. The Monster Go DJ (and Go DJ Plus) support Cyrillic filenames and they support waveform display without a PC or separate software (albeit with significant preprocessing time). The same can be said of the Hardware. Compared to the stylish partially metal chassis of the Monster Go DJ, the physical construction of the SDJ-4000, while not bad looking at all, is far more primitive. But a basic chassis design also makes for easy and straightforward disassembly.

To Disassemble the SDJ-4000, the first thing you will need is a large work area. I ended up disabling the SDJ-4000 on top of my Cerwin-Vega V-15B PA speakers. The 2 speakers pushed together provided a sufficiently large, carpeted work area. The second step is to start removing screws -- lots of them. All chassis bottom screws are the same, and all of them need to be removed, so there is no need to keep track of what screws go where. A sign of a good technician is not loosing screws, and already, effort needs to be made to achieve this. You'll definitely want a powered screwdriver for this beast. The Large feet do not need to be removed, and unscrewing (turning) them should not be attempted at this point.

Holding the unit by it's side lifting points, carefully flip the unit back over, and lift the top case half a little bit only. Be careful of several wire harnesses that connect between the 2 halves. Disconnect the Headphone cable near the front, and then lift the front a little more -- next are 2 very delicate ribbon cables -- the Display (TFT) connection, and a similarly delicate Top/bottom (actually marked as (Mixer and Rear) interconnect. Both of these cables can be released from the "Rear" board by carefully lifting the black locking feature on the connectors. Previous experience with these types of delicate cables/connectors is strongly recommended. Lastly, open the unit a little father, and disconnect the USB connection at the rear left. The top chassis can now be separated from the bottom.

SDJ-4000 Bottom Chassis and "Rear" PC board

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A few notes on the above Bottom Chassis or "Rear" PC Board --- Generally Left to Right:

• The Mic 1 1/4" TRS (Phone) connector and Mic 2 combined TRS and XLR connector, with associated input circuitry can be seen at the upper left of the board.
• Note the Analog 7805, 7815, and 7905, 7915 +/-5 and +/-15 regulators near the bottom of the board near where the foam covered power supply lead connects. Analog power supplies in audio equipment can be good, but I find the 1980's text book implementation of these regulators (Input capacitor, regulator, Output capacitor, and no heat sink or support) -- quaint. At least they bypass those cheap-looking electrolytic caps with chip capacitors.
• The mixer board connector is mostly blocked by the power supply in this picture.
• Note my repair of the broken Lithium battery holder. A 2032 cell is soldered in and double sided taped to the chassis near the incoming AC wires. The double sided tape zip tie holder was from the factory, and was found loose due to the mass of that torroidal choke. Design effort and implementation get pretty low scores here.
• Note the separate CPU module, and large heat sink. I actually have to give them a pretty high score for that. There is an additional USB or serial port (Debug?) connector just above the CPU. It wouldn't surprise me at all if there was a console running on that connector. Note also the I/O pads just below the Computer Board, and that the pads are labeled.

SDJ-4000 Top Chassis and with Players and Mixer board

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Notes on the Top Case half with Player Boards and Mixer Board.

• Note the Mixer Interconnect Cable (White) and the TFT (Display) interface ribbon cable (Yellow) near the top.
• Note the Cable With another large ferrite bead at the upper right. This connects the USB connectors to the main (Rear) board. Note that these cables are shielded, where as none of the cables carrying audio are. Headphone Jacks and cable are in the lower right.
• Note the large ARM Core Chips on each player board, apparently some of the Decoding and D to A is off loaded from the main Processor
• I find the connector arrangement on the Player boards interesting. It looks like they were thinking about having a single player board that could be installed in the right or left, but that ended up not being the case. The boards are different, and Marked as Player 1 and Player 2.
• Note the small board at the top center that interfaces the "TFT" cable to the actual display ribbon cable. This suggests to me 1.) That perhaps different versions of this device had screens from different suppliers, and 2.) Adapting different (Better/Larger) displays to this unit, or replacing a damaged screen with a "Generic" TFT display may be possible.

When reassembling the unit, care must be taken not to pinch that headphone cable between screw holes. Driving a screw through the headphone cable is -- bad. Note also that it may appear that the screw holes are metal due to the copper shielding paint -- they are not. These are not machine screws, and they go into plastic. Do not over tighten, as the plastic threads will be stripped.


Part III -- But Does it Run Linux?

I can't prove it at this point, but I am quite certain that the Gemini SDJ-4000 is running Linux. This is most evident when what looks like a Linux console is displayed briefly during a firmware update. The is no information about Linux or the GPL in the Settings Menu, the very minimal User Guide or on the Gemini Website. Note that the SDJ-4000 is apparently no longer a current product.

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Gemini SDJ-4000 Stand Alone DJ Player and Mixer

Part IV -- Running Gemini V-CASE software on Linux

So External Software running on a Windows or Macintosh computer is necessary for this "Standalone" DJ Console. I'll let that sink in for a while...

Some engineering problems really do need to be solved by lawyers -- But I digress. Let's help the situation as best as we can by at least getting the V-CASE software running on Linux.

First, they apparently don't really want you to download the software. My inability to find a download link wasn't an old man problem or a Linux problem... It's not there. A support request to Gemini was quickly answered with Windows and Mac download links -- to what appears to be just a dropbox. The answer also said that they are no longer supporting the development of V-CASE. I didn't ask for developer support, I just wanted my Gemini SDJ-4000 to display waveforms as advertised.

OK, So I now had a down load link, and I will also say that their support was very fast, and courteous.

I figured that a basic app like this should be well supported by Wine on Linux. After all the app does not interface with the SDJ-4000 directly.

Well after numerous struggles -- On a Wine installation that runs the included Internet Explorer without problem, I could not get V-CASE to run.

The installer ran fine, and I soon had a V-CASE.exe in my Wine C:\ drive, but I kept getting the following error on startup of the actual application:

Code: Select all

[JavaFX Application Thread] INFO  - Ip still is not set
Ip still is not set.

Interestingly, searching Google for this error message yielded no hits at all. Apparently, I am the only person in the known universe that has seen this particular error message. The error happens just as V-CASE is attempting to connect to the internet -- Which in itself is a problem -- There should be no reason to mandate that this app have a live internet connection. Apparently it is attempting to look up supported Gemini products --- Or just collecting user's IP address and who know what else.

Something I read suggested that Play On Linux might have better luck running apps like this that are trying to run a JRE within Windows.

That gave me another idea -- I already have an excellent and really capable Linux Windows environment -- My Valve Steam Deck.

As with basically everything I have tried on the Steam Deck, this actually worked with very little difficulty. Here's a short list of steps to install V-CASE on a Valve Steam Deck. Very similar steps should work for Steam/Proton on any Linux PC:

Note that I am not providing links to the V-CASE software -- It's pretty bad, I do not want it implied that I am recommending or advocating this software. I downloaded V-CASE-1.6.24, which Gemini Support said was the latest (last) stable version.
Update: The direct download links are in the description of this Gemini YouTube Video: https://www.youtube.com/watch?v=Rz3OzNYAw5c

• On the Steam Deck, Switch to Desktop Mode.
• Download the installer zip file. Using Dolphin, navigate to the downloads folder, Locate V-CASE-1.6.24.exe.zip, right click, and unzip it "here".
• The installer executable must be installed in Steam as a "Non-Steam Game": Open the Steam client, click "Add a Game", then "Add a Non-Steam Game to My Library," browse to the V-CASE-1.6.24.exe, and click "Add Selected Programs"
• The installer will appear in your library as a "Game" -- Launch it, and follow the prompts (without changes) in the infernal Windows installer.
• Now we must find the Proton Wine Prefix that was created for the actual V-CASE.exe (Note different name. This is the actual V-CASE application.) In the Dolphin file manager, select "View" and check "Show Hidden Files".
• Navigate from the Dolphin Home directory to .steam/steam/steamapps/compatdata/
• In this folder, there will be a random numbered folder for each Windows app installed. The one we just installed should be the largest (last) folder. Select that folder and navigate to ##############/pfx/drive_c/Program Files/
• In this folder should be (finally!) our installed V-CASE.exe (Note that there is also an uninstaller, but you can just delete the prefix by removing the "Game" from Steam.
• Again right click and select Add as Non-Steam Game
• Go back to your steam library and you should now have both the V-CASE-1.6.24.exe installer and the V-CASE.exe app. Launch the V-CASE.exe "Game", and it should load and run.
• A few other notes:
  • You will probably want the Steam Deck in a dock for this, You'll want a keyboard and mouse, and the USB drive that you will be using in the SDJ-4000 plugged into USB ports on the Dock. An external monitor would be nice, too, but not necessary.
  • The Steam Deck will not stay awake even when active processing of your files is taking place. Set the Steam Deck (or PC) so that it does not sleep.
  • On my unmodded Steam Deck, it was "Analyzing" files at approximately 60x, in other words, it took about 3 seconds to process a 3 - 4 minute song.
  • I am having some difficulty with fonts and colors on the Steam Deck -- This, and the small size of the Steam Deck screen, make reading menu and dialog text very difficult. Perhaps trying different Steam compatibility tools (i,e, Proton 9, 8, 6.3) may help. I was using Proton 9 for the above steps. (Update: Using Proton 8 seems to have helped somewhat with the issue of font colors (Including transparent fonts) in the PC V-CASE software.)

Another route to getting this running on Linux may be to simple run it natively -- It seems to be a Java App, and the installed V-CASE.exe can be opened as an archive. However, since I have it running on my Steam Deck, and I don't have the patience or the knowledge, I do not plan on making any attempt to do this.


Part V -- Comments on the V-CASE software

So obviously I would like V-CASE better if there was a native Linux version -- especially since it doesn't seem like it would take a lot of effort. It would be even better if the "Standalone" SDJ-4000 wasn't dependent on a separate PC. That said, It does work. It makes a very good MP3 file manager, Tag editor and Playlist creator. It also functions as an MP3 player with a Waveform Display.

As mentioned, V-CASE is also pretty fast. Importing, analyzing, and writing out over 1500 MP3 took a while, of course, but noting unreasonable at any step (you'll definately want a fast (USB 3.0 or better) USB Drive -- not that the SDJ-4000 requires it, but your patience will when you want to initially write all the files to the drive you'll use in the SDJ-4000.

I created a master playlist of the Files in my "DJ Master" folder, except of course the FLAC files. It also seemed to refuse to import a handful of other files (out of that 1500+). A few of the files it rejected may have VBR info issues due to a known LAME MP3 VBR bug, but all load and play, and others were not created by LAME, and do not have VBR issues.

Also, V-CASE processes files based on their ID3 tags. It does not make any attempt to look up songs in a music database or add or correct tags. You can't for example, tell V-CASE that all your filenames are in <tracknumber> - <artist> - <title> format, and then have it create the tags.

So in other words, It's garbage in - garbage out. This means that for these files, searching by artist, album, date, etc. won't work.

Before importing your files into V-CASE, you must first use something like MusicBrainz Picard (which is available for Linux) to fix/add your tags.

Remember my complaints about Cyrillic filenames? V-CASE replaces Cyrillic ID3 info with a long line of question marks, and then shows the ID3 instead of the filename. Before processing, I could at least navigate to the Folder (Album), and see the tracks in the 2 pane display, I could remember that the track I wanted was -- for example -- the 3rd track, and then select and play the correct file --- after processing, forget it --- finding selecting a track is impossible.

So, in short, I am back to where I was before all of this effort. I will use a USB drive with unprocessed files on it, and thus have no waveforms displayed.


Part IV -- Avoiding the V-CASE Software

So without the V-CASE software running on a Windows or MacOS PC, your "Standalone" SDJ-4000 won't create/display Waveforms on tis' own as both the Stanton SCS.4DJ and Monster Go DJ do. The other thing that will be missing is the Album Art -- Even if your MP3's have Album Art correctly encoded in the file, and/or there is a separate cover.jpg in the folder. (The Stanton SCS.4DJ even in pure standalone mode, does properly display album art.)

There than those features (which are both pretty basic and pretty critical), the SDJ-4000 can limp along in an actual Standalone configuration.

Here's some hints to get the most out of the SDJ-4000 in a true Standalone configuration"

• Make sure your files have standard ID3 tags, and that those tags do not include special characters (Unicode, foreign, etc.)
• The SDJ-4000 does seem to process files somewhat on it's own, but I don't understand how it picks which songs to process, or exactly when it does the processing. Select at least 1 song in each folder, and then press down on the Navigate encoder (Add to playlist). This will add the track to a playlist called "Track Prep". If you press Playlist, and navigate to the "Track Prep" folder (Track Prep without a date), you should see that the track is now listed by it's ID3 info, and has turned from Red text to White text. If you now navigate back to the folder, the track should have also turned to White text. I should also have any other info from the ID3 information, and be searchable accordingly.
• There are a few problems, however. Some tracks will never turn white. Others may or may not turn white after several attempts/power cycles. Different tracks from the same Album, download source, or even files obtained in the same downloaded .zip, may or may not process. Often selecting 1 file from a folder will result in the entire folder seeming to be processed at once. I've never actually seen a track turn from red to white in either Browse or Playlist. One possible explanation for what I have observed is that whatever process does the track processing crashes on certain files. Thus if you power cycle the unit, you can do some more files until the process fails again. It does not seem to process files without some action from the user -- i.e. loading a file into a playlist or one of the players.
• You can also create and load Samples without the V-CASE software. To do so (and assuming that the USB drive has already been used with the SDJ-4000) Create a folder called "Samples" (exact case and spelling) in the SDJ-4000 folder. Copy your samples to the Samples folder. So far, I have tried 48000 and 44100 samples/sec wave files. Next, append "_SAMPLE_1" to the end of the filename to have the sample load onto button (pad) 1. Leave the extension. So in other words Laughter.wav becomes Laughter_SAMPLE_1.wav. Bass_Beat_SAMPLE_2.wav would load onto button 2.
• In Settings, you must select USB 1 or USB 2 as the sample source for each player. As of right now, it would take 2 USB drives to support 8 samples, with each drive selected as the Sample source for each player. If you use only 1 drive, as of right now, I only know how to save 4 samples.
• There seems to be another bug with this. The buttons change color as if there were a sample associated with each one, but no sample will play until you load a track into each player. This isn't a big deal, since you'll probably want to play an actual track at some point, but this behavior seems like it fits in the "bug" category to me.
• These another "bug" with this -- Since the above does not use the V-CASE software, the SDJ-4000 database is not updated with our sample files. They do not appear in the Sample Playlist. There is no way to see the filenames or to know what file is associated with which key without either remembering them yourself, or actually playing them.
• Now before anyone (Gemini?) jumps on me for being too critical, I will admit that this is essentially the behavior of the Poor Man's Go DJ. The files must be named a certain way that forms the association between a sample file and a particular pad, and it is not possible to display the sample names or filenames. However, I do not have to load a track into a player first, and I can adjust the volume of the sample separately -- i.e. to play the sample louder or softer than a music track that is playing. This does not seem to be possible on the SDJ-4000.

Part V -- Conclusion

I have repaired my SDJ-4000, and it is now -- to the best of my knowledge -- working as it should. For now -- and again, I'll admit my bias toward a device that overall is of my creation -- I plan to continue to use the Poor Man's Go DJ.

I have a pretty important event, at a major and very prestigious venue this coming weekend, and the SDJ-4000 will stay in the shop. The Poor Man's Go DJ will be my prime player, with the Real (Monster) Go DJ in the truck as a backup. I have a less critical event the following Saturday, and I plan to give the SDJ-4000, with unanalyzed files, a shot -- with the Poor Man's Go DJ as a backup. After that, I will probably put the SDJ-4000 up for sale.

While I fully admit that the Poor Man's Go DJ is unusable for serious DJ work, I feel I would have to say the same thing for the SDJ-4000 in a purely standalone (as advertised) mode.

Thanks for reading this far. You now know more about the SDJ-4000 than anyone wants to, and I hope I have assisted with a repair or with a decision about purchasing a new or used SDJ-4000.

Please check out my other "Pro Audio" articles here.