compilerbitch: That's me, that is! (Default)

Hi folks.

Tonight I had a bit of determination come upon me, so I decided to have a go at a couple of fixes on two newly acquired pieces of studio gear: an Ensoniq DP Pro and a Yamaha SPX 900. Both are digital reverb/multi-effects processors at the middle-end of the market for their time. Both are long obsolete, but they (now) work great and I’m happy to have them.

OK, so first up was the SPX 900. This was an easy one — just a dead battery. Like most pieces of studio gear from that era, this device uses battery backed static RAM to store user configuration information and patches, so when that battery dies, usually after about 15-20 years, it’s time for a new one.

Yamaha SPX 900

Popping the lid off shows some admittedly fairly old technology, but this thing is built like a tank. Surprisingly, the power supply on the left appears to be linear — no switching regulators in sight! Badass. Anyway, it just took a couple of minutes to desolder the battery (you can see it as an orange ring with a silver center on the bottom right) and solder in a replacement.

SPX 900 Display

On power-up, the first time I got a message saying that memory corruption had been detected (well, duh), then on a second power cycle it just came up fine straight to patch 1, like it’s supposed to. Before the battery swap, it was giving a battery low warning on power up. It didn’t have any user patches in it that I cared about, so I didn’t bother saving them (e.g. via MIDI sysex) or doing something heroic with a lab power supply.

Next up was an Ensoniq DP Pro. I just got it a couple of days ago — it was seemingly working, but the LEDs on the left of the front panel didn’t seem to be doing anything, nor did the 4 digit 7 segment display. I did a minor gulp when the person who sold it to me mentioned that he’d had his tech replace the battery  — this always makes me worry, because I’ve had way more beyond-economic-repair situations caused by hamfisted repair attempts than actual failures. True to form, on investigation, someone had made like a gorilla with a couple of ribbon cables that normally go between the main board and a 2 board stack that includes all the displays that weren’t working (bottom left on the disassembled view). Not only had they ripped them out, they just tucked the damned things in so it looked like they were connected. ‘Ere, it just came off in me ‘and, Guv. Anyway, after a bit of faffy taking the front panel assembly apart so I could get at the connectors, it seemed that the fine pitch ribbon connectors did look slightly damaged, but they did still work. Similarly, the cables had seen better days, but did work fine once I reassembled everything.

Ensoniq DP Pro internals

Yaay, lighty up blinkenlightythings!

DPPro display fix

Anyway, a quick word about these two processors. I must say, they both punch above their weight. The SPX-900 really does feel like the classic SPX-90 on steroids — a much cleaner sound, though not quite as buttery smooth as a REV-5. Many more algorithms, though, including a couple that are heading toward Eventide’s Black Hole algorithm. The reverbs are typically Yamaha, not as colored as those from something like a Lexicon or quite as weird as an Eventide, but very usable indeed. The DP Pro was a bit of a surprise — it really is excellent. I’d put its sound as being somewhere between a Lexicon and an Eventide, in the sense that it sounds good and dense, but it’s capable of plenty of batshit. It has a dual algorithm structure, where the algorithms can be set up to work in series or in parallel, rather like an Eventide Eclipse. I think this thing is an unheard-of classic waiting to happen, so I’m glad I got my hands on one before someone famous decides they are cool.

Fixing things always cheers me up — I’ve no idea why. :-)

Please note: this was cross-posted from my main blog at -- If you want me to definitely see your replies, please reply there rather than here.

#MoMBlog, #MusicGear, #Recording


compilerbitch: That's me, that is! (Default)

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