All posts by Tom Virostek

I’ve had many people ask me about the DI-10 digital interface for the ASR-10. The most common questions are:

Is it still available, and what’s the price?

Yes it’s still available, it’s $179.00 plus shipping. The 20-pin interface cable is different for the rack version, so please let me know which version (keyboard or rack) you have.

You mentioned that there are issues related to heat buildup in the ASR-10 rack which prevents use with the DI-10. Have you come up with a solution?

I did originally believe that to be the case, but now I am convinced that that was a one-off problem with a particular ASR-10 rack. I have had several people install the DI-10 in their ASR-10 racks, and there hasn’t been any problems (that I’ve been made aware of, anyway).

Older ASR-10’s tend to have more issues due to component differences and age of the machine itself. So it’s possible that you could encounter issues with the DI-10 (similar to the 44.1kHz problem with the SCSI board). Unfortunately there’s no way to know if the DI-10 will function properly until you install it.

Happy 2023! Hopefully this year will be better than the last few years have been.

As you’ve probably gathered, there hasn’t been much going on here. COVID has impacted the supply chain so it’s become more difficult and expensive to produce PCB’s. Therefore, I won’t be doing anything new for a while.

The DSS-1 upgrade is essentially discontinued. Since I was building them myself, I found it took around 7 hours to assemble, test, program, modify existing boards, etc. per kit. And there are some outstanding software issues which I don’t expect to be fixed anytime soon. So I’ve opted to focus my efforts on a different approach to the upgrade. However, I don’t expect to make progress on this (or the DSM-1) anytime soon.

I do still have the following:

ASR-10 SCSI and digital I/O, EPS-16 SCSI and Flash Bank, and CEM5530 replacement modules

In addition I will no longer offer repair services to equipment (other than the boards that I have sold).

The latest batch of DSS-1 kits are now sold out. The next run won’t be until the end of the year.

There is no waiting list, preorder, or deposit. I’ll announce the availability of the kits right here.

There are still ASR-10 SCSI and Digital I/O, as well as EPS-16 SCSI and Flash Bank. I also have the CEM5530 modules in stock.

I have 25 kits available immediately, the price is 300.00 plus shipping, first come, first served.

Now the details:

  • I no longer offer the LCD upgrade or floppy/combo drives. The LCD upgrade is fairly simple to do for most users. The procedure is detailed in the installation guide (under Downloads).
  • The KLM780, KLM782 boards (with attached KLM-1061) must be sent to me for modification. I discourage most users from trying to do the modification themselves, unless you are an experienced technician. It becomes difficult and costly to try and solve post-installation problems, especially if you are outside of the continental US.
  • There is no discount if you decide to install yourself. I’m offering free installation as an incentive to avoid further problems down the line.
  • A Gotek drive can be used with the upgrade, though it’s really only useful for importing disk images to the ‘native’ file based format. The same goes for a regular floppy drive. Once your floppy disks are imported, it isn’t really necessary. A better solution might be a 3.5″ multi card reader with additional USB port.
  • Please allow 2-3 weeks for modification.
  • LCD modules are available from several sources: eBay, BuyDisplay, Newhaven Display, Crystalfontz, Focus LCD’s, Ali Express, etc. You will need to consult the data sheet for pinout information. Some displays have a current limiting resistor on the display module itself, others don’t. OLED displays currently don’t work properly, but this is being worked on. The module format is 20×2 characters, 116mm x 37mm module size.
  • You will need to run the memory test BEFORE sending the boards in. If there are errors, the boards will require additional repairs, the cost will depend on parts and time. The upgraded DSS-1 won’t boot if it detects memory errors.

Version 4.06 fixes some system exclusive bugs and adds a few features.

You can download it here

Unzip the file, and put the two .bin files on the root level of a USB drive. Boot the DSS-1 into test mode holding the DATA A up/down buttons until you are asked to upgrade the OS. You may have to disconnect the USB device in the other port in order for the upgrade to be recognized.

Change list is included in the .zip file

Huge thanks to Jim Babb for continuing to support and enhance the DSS-1 after almost 35 years. For those of you who don’t know, Jim is the creator and programmer of the upgrade from 1987 along with Paul Kreter.

I’ve now gotten confirmation that issues working at 44.1kHz are present on the original Ensoniq SCSI boards. At this point it seems that certain manufacturers, or possibly batches of IC’s are the source of the problem.

The SCSI board provides circuitry to isolate the signals to and from the DAC and ADC to eliminate noise and jitter. One of these signals is the 256Fs clock (256x sample rate) which is over 11 Mhz. Because of the design of the circuit, IC’s that are slightly out of spec won’t work properly. This isn’t the whole source of the problem, though. Some ASR-10’s exacerbate this situation, which I believe may be related to the revisions of the custom chips on the main board. So a SCSI board with an out-of-spec IC may work fine in one machine and have problems in another.

I have suggested a possible fix to a user who has this issue, if the fix is successful I’ll post it.

I’ve finally resolved the issue that was affecting some ASR-10’s from working properly with the SCSI board.

I’ll do another post with an in-depth discussion of the issue, but I’m almost certain that this issue affects the original Ensoniq SCSI boards as well. Unfortunately I sold the only genuine SP-3 board that I owned, however I’m building a few of the older generation of the SCSI board (which is 99% the same as the Ensoniq board) to verify this.

If you have an original Ensoniq SCSI board in your ASR-10, you can check for the problem by toggling between 30kHz and 44.1kHz. At 44.1kHz you will hear distortion or audio artifacts. It doesn’t happen every time you switch, and it will sound slightly different each time.

If it turns out the problem does exist on the original SCSI boards, I will be offering a solution to fix it.

I haven’t updated things in quite a while. I hope that you are all well and that the pandemic hasn’t impacted you too severly.

Personally I have had some substantial changes this year. I quit my day job back in July. Besides having to spend 3 hours each day in the worst traffic in North America, I absolutely hated the job. I’ve had more time to work on some of these projects (though, a lack of income has hampered that somewhat…)

Here’s the status of various projects at the moment:


Parts are becoming more scarce and the ones that are available have had an increasing defect rate. Nevertheless I have been making small quantities of the upgrade. Some very good news is that there will be a firmware update that fixes some major MIDI bugs with system exclusive transfers. I’m also working on a Midi Quest profile to handle the expanded sound and sample banks.

The DSS-1 upgrade will be $350.00 including installation once it’s available.


I stopped selling the SCSI board for the ASR-10 as an issue cropped up with some ASR’s when using a 44.1kHz sample rate. Frustratingly, my ASR-10 here didn’t have the problem, nor did a second unit that I purchased. Finally, I just received and ASR-10 that exhibits the issue and I have been able to trace the source of the problem. I’ll do a separate post about this. Hopefully the problem will be resolved and the boards will be available again in January 2021.

Once available the SCSI kit will be $199.00 plus shipping.

The DI-10 digital I/O board will be undergoing a redesign to make it all surface mount (as many companies won’t do through-hole assembly anymore, and through-hole components are disappearing from many suppliers’ inventories). Many of you have asked if the overheating problem with the rack ASR-10’s have been solved (as it relates to the sample rate of the interface). I now believe that it is not limited to the rack but the keyboard as well. It seems that the earliest revisions of mainboard (the ones with lots of wire jumpers) are prone to this issue. One of the ASR’s that I have has this issue, so I may be able to come up with a solution.

The DI-10 kit is $179.00 plus shipping.


Both the SP-2 SCSI kit and FB-2 Flash Bank are both available. I did have an issue with an incorrect resistor on the FB-2 which resulted in intermittent operation. This has now been corrected.

Both kits are available for $159.00 plus shipping.


The CEM5530 clone is still available.

The price is $75.00 each plus shipping.


I have both the I-627B adapter (for rev A machines) and the 4 MB memory expansion available. Rev. A machines require the I-627B voice chip upgrade to properly address additional memory. Unfortunately the only source for this chip was Wine Country Productions, who have stopped selling it due to a high defect rate. Those lucky few who have purchased and I-627B with hopes of upgrading can upgrade to the full 8 MB (4 Megaword).

Both the adapter and the memory expansion are $99 each plus shipping.


I have developed a memory expansion for the Prophet 2000. This will be going into production soon.

Price TBD.


I have the 2MB memory expansion available as well as the memory terminator.

The price is $129.00 plus shipping.


Though the OB-Mx voice board has been complete for some time, some of the IC’s are completely unavailable now, particularly the CEM3382. I have made an adapter board to use the SSI2162 VCA, which is undergoing testing. At this point it’s not economically viable to produce these boards but that may change in the future.

Price increase: Sharp-eyed readers will notice that prices have gone up. I’ve had to outsource most of the assembly and testing, and component prices have gone up, as well.

Shipping: I now ONLY use Parcel Monkey for international shipping. The rates are not much more than shipping through the post office and they are much more reliable, and faster. Generally, shipping outside of the lower 48 states will be $40-$50 (Canada is slightly cheaper).



Specifically, the older ASR-10 SCSI boards with a “WD” square SCSI chip need to have this chip replaced. Also, the Flash Banks that I have sold that have a 2.2k resistor in the R9 position need to have that resistor replaced with 100 Ohm. I will do either repair free of charge.

The ASR-10 SCSI boards are now back in stock. Featuring an all-new design using surface mount components, jumper-selectable active SCSI termination, and a new lower price of $199.00 USD (down from $249.00).

The board also supplies SCSI termination power and can power a SCSI2SD with it.

Use the Contact Form (not the comments) to order a kit. Shipping is 10.00 USD in the continental USA, 30.00 rest of the world. When ordering, let me know your PayPal email address and where you live.

I no longer ship USPS, as there have been too many lost packages and delays.

All new SMT design.