Turtlerock Forum

I picked up a sick Eventide 910 pitch shifter on a whim.

I think (I could be wrong) it's the first ever pitch shifter and was circa 1977.

Any users out there? Past or present.
(I know it'll be very lo-fi compared to modern FX)

I'm awaiting for Eventide to mail me the service docs so I can (hopefully) fix it up..

For some reason I'm a sucker for pitch shifters.. Weird as they are often a bit of a one trick pony.

Mike, I used to have a 949... Loved that thing !
Try reseating the chips.

Cheers

NYMo wrote:Mike, I used to have a 949... Loved that thing !
Try reseating the chips.

Cheers

Unfortunately the IC's are mostly soldered in.
I've sussed around with a scope and the signal drops off early on before the ADC, which is promising (fingers crossed).. I think it may be one if the DBX compression/expansion cards.
And I found a fried resistor but can't make out it's value.. Still waiting for schems to arrive.

I listened to a few YouTube vids of the 949 and it sure sounds cool..

Yeah, that what they usually do with the ic's in the Eventides 910/949... Solder them in !
I hear some of the parts are unobtanium !

Cheers

I have had working versions of both , I tried and tried
To figure out why I had them
I could not find a real use for them tracking or mixing

There's a really nice effect on the end of an old Spooky Tooth album, where the last chord of the song repeats and then gradually speeds up until it disappears !( in a miasma of digital hash) That was the Eventide.
The feedback control on the 949 is the magic component .

Cheers

I think it may be one if the DBX compression/expansion cards.
And I found a fried resistor but can't make out it's value

Those old DBX cards used tantalum caps to bypass the supply rails so that's the first place I'd look on any gear of that vintage. Those tantalums are notorious for going short circuit and pulling down a supply rail.

My advice would be to check the supply rails before you do anything else.

If any of the supply rails don't meet spec then remove the DBX compander cards and check again. The cards are usually socketed with Molex connectors.

If the supply rails are OK after removing the DBX cards then you've found your problem.

The tant's are usually in close proximity to the opamps... replace all of them.

In any equipment of that vintage I always replace the the tantalum bypass caps as a form of preventative maintenance.

Note: Do not replace the tantalums with electrolytics in Neve gear. The tant's in the the old Neve modules are used as coupling caps and are integral to the Neve sound. It's very rare you'll find a faulty tantalum when they're used as a coupling cap.

Hope this helps

Cheers Greg.

The PS is within spec, even with the DBX cards attached.

I will be replacing all the tantalum caps regardless, but after scouring around GroupDIY it seems these have a reputation of being difficult to fix, I don't think because they have impossible to source parts (I searched around and a few of the odd IC's I was able to source online) but more from it's complicated design.

I think will be a bit clearer after I get hold of the schems.

(I doubt it, but anyone here have a copy?)

I think I have a manual for the 910 at home (along with a 910) Tricky little beasts , all gate logic. It's been some years since I worked on one , early 90s from memory.
The compander cards were popular with the 10 bit D/A to get the noise down. I think it used AD532 chips , near impossible to find these days, I have similar era profanity delays which use similar D/A in their delay lines
Classic device of the era

I think the H910 is a fantastic device as an fx. Not so much these days as an actual harmonizer - software probably does it just as well, if not more modern Eventide boxes.
The H910 has a nice short delay, great for stereo guitars with a bit of pitch shift.
It's a classic sound on snare with a bit of dipping lower pitch. Think David Bowie early 80's.
I have one, which was working perfectly until a few weeks ago.

Woot!

Fixed it! Very happy.

I seriously doubted I'd be able to fix it..A few times I was thinking "why did I buy something broken again?"

Among other things, a sick tri-state buffer had crippled it. ($2 IC) only took about 5 hours to find it!

I only had the shortest of plays with it, but it does what it says on the box.

Well done ! How good does it feel to fire it up after spending all that time tracking down the fault and hear it work again...

... I found a nice use for a harmoniser on single note xylophone tunes last time I played with one (er um 35 years ago) - pitch shift up 1 octave and all the delays on - turns single notes into a trilly roll that disappears into the heavens - sounds pretty ... the pitch knob sweeping can turn it into a spacy synth

Good work getting it fixed - these often appear on ebay in the "not working" category for fair $s ....

They'e highly prized by guitarists, you'd have no problems selling it on a guitar forum (...should you be so inclined).

Cheers.

Trust me, I was in shock when I fixed it. Then I did a happy dance for a while, Then I thanked my new digital scope with a little kiss!

I fixed it mainly for myself to keep.. But I can see why guitarists would want one. (Brian May used one?)
They don't have a blend control curiously, and only screw down connectors.. This may scare of the newbs.
Mine does have transformer coupled ins and outs, which is nice.

Next is to repair an Oscar synth and an Akai S612

Congrats on the 910 Mike
( and good luck with the Oscar !)

Cheers