Hacking the Alesis Ineko

[drew]

So I popped open my Alesis Ineko this afternoon...

It's got two TL082 surface-mount opamps in there... and guess what else? An AL3102, AL3201, AL1101, and AL1201. It's got an LM339 (this is a comparator; I assume it's for the input/overload LED control) and microprocessor as well. The AL1101 looks to be an A/D and the AL1201 a D/A, based on their connections and placement.

Screenprinted on the top side of the board is the message, "We're glad you're interested in our designs. Alesis ICs are available at WWW.ALESIS-SEMI.COM". I think that's great

I might dead-bug some burr browns in there, but before I do, d'you think there'd be enough of a difference between a TL082 and a BB2134 or similar to make a difference? (In the original thread, Peter Snowberg suggested an op-amp replacement to clean up the sound a little.)


drew
toothpastefordinner.com

[drew]

And right away I notice on the spec sheet (for the application kit) that the AL1101 is hooked up to 5532's instead of TL082s. Well, that'd make a difference, huh?!


drew
toothpastefordinner.com

[Peter Snowberg]

Screenprinted on the top side of the board is the message, "We're glad you're interested in our designs. Alesis ICs are available at WWW.ALESIS-SEMI.COM". I think that's great

That's too cool!

There is a message in several of the early Macintosh ROMs that says, "Hey! What are you looking at?"

I would go beyond just replacing the opamps and replace the whole analog end of the circuit because of the cheap ceramic caps with the cheap op-amps. I picked up a PicoVerb and the Alesis Semi app notes have much better filtering in them. The A/D and D/A take differential signals and are easy to interface with.

Good luck! I'm really curious about what you come up with.

-Peter

[Dan N]

I might dead-bug some burr browns in there

Cool expression! What the hell does it mean???

Dan


edit-- dead bug= upsidedown chips
        burr browns= a high falooting chip maker?

Damn, I wanna dead bug some burr browns too!

[drew]

"Dead bug" refers to the technique of hot-gluing a DIP IC on its back (it looks like a dead bug- feet in the air!) and wiring the pins, using wire-wrap wire, to a surface-mount circuit, or a circuit where the original chip had a different pinout.


drew
toothpastefordinner.com

[ExpAnonColin]

There is a message in several of the early Macintosh ROMs that says, "Hey! What are you looking at?"

I would go beyond just replacing the opamps and replace the whole analog end of the circuit because of the cheap ceramic caps with the cheap op-amps. I picked up a PicoVerb and the Alesis Semi app notes have much better filtering in them. The A/D and D/A take differential signals and are easy to interface with.

That's so cool.  If I ever make designs, I'm putting something witty on them as well.

Replacing the cheap SMT things is not a good idea! (I'm just assuming they're SMT)

And drew, I just went to your website, I love your work.

-Colin

[Peter Snowberg]

Replacing the cheap SMT things is not a good idea! (I'm just assuming they're SMT)

Not a good idea?  :?

It's pretty easy really.... You can make up new filtering stage on perfboard and solder a couple of jumpers down to the A/D and D/A pins. From there it's easy to jumper to the jacks too.

There isn't much to see in the PicoVerb, but if you look in the Alesis Semi datasheets you'll see a much more complete set of filters. I assume other products are similar.... just my assumption.

I build as much as I can with SMDs these days. I find it's faster and easier than dealing with regular leaded components when you're talking about resistor, caps, and transistors. SOIC chips are easy to deal with too. When you hit QFP packages it mandates making a PCB, but until then you can easily work with double sided, plated, pad-per-hole perf board.

-Peter

[drew]

A magnifying glass, a steady hand, and ain't no problem to change out some SMT parts! I was staring at it on my desk this morning and realizing I could order a couple of SMT NE5532 chips to make things easier.

Peter, what kind of filtering are you talking about for the A/D-D/A? My schematic for the app kit shows a 4700pF cap between the differential inputs to the A/D, and the rest of the caps just look like 0.1uF bypass caps going to gnd or +V. However, there's an RC pair on each input and output; these were the caps I was going to replace.

Oh, also I forgot, there's a pair of larger SMT caps in the signal path between the opamp (which acts as a buffer/balancer to drive the A/D, and the other works in reverse on the output) and the A/D which show up on the app notes as 10uF electrolytic caps... I'll probably replace those with film caps since I know better than to leave 'em there.

Now here's something interesting, possibly of future use to people: I found a SMT cap marking guide here: http://www.nerdvest.com/elec/Capacitor_Values.html and here: http://www.netcentral.co.uk/satcure/hobby/smdlist.htm

The large caps I mentioned before are marked "VS5".... not sure what's going on here since that list doesn't mention three-letter markings except for electrolytics, and then it doesn't mention the V part! Regardless, it looks like S = 4.7, 5 = 10,000 pF, so this is 47,000 pF, or 47n, or 0.047uF, however you like to write cap values. Someone please correct me if I'm wrong!

At any rate, these look like DC blocking caps in the signal path, so I should be able to replace them with something that's not quite the same value. Maybe something bigger, if there's room, to let more bass through.


drew
toothpastefordinner.com

(PS. Thanks colin, you should grab some of the music, a lot of the synth and guitar parts on it were run thru homemade fuzz-tortion-overdrive boxes...)

[drew]

I'm not the world's best photographer, but here's a pic I took of the inside (warning- it's quite large- 200k and 1600x1200!)

http://www.toothpastefordinner.com/ineko-inside.jpg

From the upper left, going right: TL082, AL1101, TL082 on top of AL1201.

drew
toothpastefordinner.com

[Peter Snowberg]

Thanks for the pic!

I'll analyze the circuit and get back to you with more info later tonight.

One quick note: Notice the labeled pad below (SEND) and the three pads above the 87C52 micrcocontroller. (TXD, RXD, RESET) The PicoVerb has the same pads, but they're not marked. I have not looked for activity there (I don't want to get into any hot water for reverse engineering their code, so I'm staying away from that).

-Peter

[Peter Snowberg]

double posting strikes again, oh well... might as well replace it something

Take a look at the circuit board and then look at the D/A eval schematic. The Eval board uses differential outputs from the D/A; combinig them in the filter where as the above Ineko is just taking single ended outs from the D/A. One more hint... They're filtering and buffering with a single opamp. If you use two 5532s to filter and then buffer.....

Funny... now that I look at it more, I don't see ANY filtering (other than a simple cap to ground) on the outputs.  :twisted: That could explain a LOT.

Are there any parts on the bottom of the board?

-Peter

[drew]

Here's part 2, which has comments on my mods, a picture of them, and a post-mod audio sample:

http://diystompboxes.com/sboxforum/viewtopic.php?t=15742


drew
toothpastefordinner.com