KVR Audio

Kriminal · Post by **Kriminal** » Wed Jul 30, 2014 6:13 am

Much respect...i could never do that....looking fwd to audio demos

whyterabbyt · Post by **whyterabbyt** » Wed Jul 30, 2014 9:05 am

That's some progress Justin. Kudos.

justin3am · Post by **justin3am** » Wed Jul 30, 2014 9:09 pm

Thanks guys. It's been a lot of fun to work on. It feels like the time just flew by.

Dave, I would have said the same thing 5-6 years ago. I think it was in 2008, I told Sickle that I didn't want to get involved with Reaktor because I was worried that it would affect my music output.

Building stuff like this is pretty easy, it's a lot of work but it's all like paint-by-numbers... Except the 'paint brush' can burn you and things can blow up if you use the wrong 'color' in the wrong place.

I'm working on learning to analyze filter topologies, so I can start building my own designs. This involves difficult maths and is much harder than building something from a kit.

robogone · Post by **robogone** » Wed Jul 30, 2014 9:15 pm

Looking good. I used to be able to do a lot of that, and at college did a ton of calculus involved in electronic design, but now I'm sure I barely remember any of it.

I think I would just lack the inclination to do so much work on it now, but it's awesome that you're making that kind of progress with it.

Can't wait to hear what it sounds like!

SJ_Digriz · Post by **SJ_Digriz** » Wed Jul 30, 2014 9:20 pm

Great work! I had a blast building an SEM variable state filter and a Buchla Source of Uncertainty clone, amongst other modules. It's a bit addictive ... I wonder how filter xxx works compared to filter y? The never ending question.

Hink · Post by **Hink** » Wed Jul 30, 2014 11:01 pm

justin3am wrote:Thanks guys. It's been a lot of fun to work on. It feels like the time just flew by.

Dave, I would have said the same thing 5-6 years ago. I think it was in 2008, I told Sickle that I didn't want to get involved with Reaktor because I was worried that it would affect my music output.
Building stuff like this is pretty easy, it's a lot of work but it's all like paint-by-numbers... Except the 'paint brush' can burn you and things can blow up if you use the wrong 'color' in the wrong place.

I'm working on learning to analyze filter topologies, so I can start building my own designs. This involves difficult maths and is much harder than building something from a kit.

I would love to build one, but I still have a pedal to finish out of the few I bought a year plus ago though

. Are you using any magnifiers when you work? I wear Bausch and laumb magnifying goggles when I am populating boards but tbh I have not done anything since getting my glasses a year ago, the glasses might make working easier

Hink · Post by **Hink** » Wed Jul 30, 2014 11:01 pm

SJ_Digriz wrote:Great work! I had a blast building an SEM variable state filter and a Buchla Source of Uncertainty clone, amongst other modules. It's a bit addictive ... I wonder how filter xxx works compared to filter y? The never ending question.

you built a nice amp too

SJ_Digriz · Post by **SJ_Digriz** » Thu Jul 31, 2014 12:04 am

Hink wrote:
SJ_Digriz wrote:Great work! I had a blast building an SEM variable state filter and a Buchla Source of Uncertainty clone, amongst other modules. It's a bit addictive ... I wonder how filter xxx works compared to filter y? The never ending question.
you built a nice amp too

true.. and it is a great amp at that.

thanks for the reminder

Sendy · Post by **Sendy** » Thu Jul 31, 2014 12:47 am

I envy you. I'd love to be able to build on of these. I did a bit of soldering at college, but it was a very long time ago, and we didn't get much taught to us. Basically, just like, ok, that thing with the smoke rising from it is hot, don't touch it.

We were already quite familiar with pointy things that are hot at one end with smoke rising from them, so this was no suprise.

SJ_Digriz · Post by **SJ_Digriz** » Thu Jul 31, 2014 12:54 am

Keep at it Justin. That stuff is way cool.

justin3am · Post by **justin3am** » Thu Jul 31, 2014 5:23 am

Hink wrote:Are you using any magnifiers when you work? I wear Bausch and laumb magnifying goggles when I am populating boards but tbh I have not done anything since getting my glasses a year ago, the glasses might make working easier

No magnifiers for this kind of thing, my vision is pretty good with small stuff in low light. At work, I use a stereo microscope when I'm soldering really small parts. I have a set of magnifier goggles but I don't use them much.

justin3am · Post by **justin3am** » Thu Jul 31, 2014 5:36 am

I finished the last voice card!

I hooked up my Beatstep and some headphones and rocked out for a bit. The filters sound fantastic!

It's tough to get very deep since I can only see what I'm controlling by referencing the manual. The different oscillator modes are really cool and with a little bit of modulation it can sound like a maniac.

I should be able to record some stuff tomorrow night. If not, definitely this weekend.

justin3am · Post by **justin3am** » Fri Aug 01, 2014 5:43 am

Tonight I found that voice 6 was much louder than the rest. I started to troubleshoot by replacing the second voice card in row three with the second voice in row two. The voice card that was originally louder now sounded fine and the card that was now in row three was louder. That means the problem was not in the voice card itself.

I then removed the second voice card in row three, so there was only one card in that row. When the jumpers on that voice card were set to 'A' there was no problem. When the jumpers were set to 'B' the problem occurred. I figured that there could be a problem with the header but it was more likely to be on the main board. I quickly checked the header for shorts but didn't find anything and when I swapped the voice card that was in row three for another, the problem persisted. I thought it was safe to assume that the problem was on the main board.

Luckily the analog signal path between the voices and the jacks is very short and there are just a handful of resistors. I started by measuring the impedance of the individual resistors that connect to the per-voice outputs. They all checked out. I then checked the resistor network next to the TL072. Oops, the lead that connects to voice 6 measured 10k but the others measured around 20k. After close inspection the problem was obvious… I had installed the the resistor network backwards.

I was able to get the part out without damaging it, but I replaced it with a new one, just in case.

After that everything is peachy. I need to tune the filters but other than that and the display, it's ready to play.

Here is the first sound I have recorded from the Ambika.
https://soundcloud.com/justin3am/ambika ... -and-stuff

I just held some chords, swept the lofi vowel wave, the sample rate reducer, and then played with the filter a bit. Nothing too crazy. It's really hard to tell what I'm doing without any feedback.

I think it sounds great! Yeah, tons of aliasing but if you haven't guessed already, I'm into that kind of thing.

There are some band-limited waves but those are pretty basic compared to all the fun wavetable, fm, phase distortion, etc. stuff it can do.

justin3am · Post by **justin3am** » Fri Aug 01, 2014 7:52 pm

FFFFUUUUCCCCKKKK!!!!
The display arrived today and in my excitement, I installed it without reading the build instructions carefully... I used a jumper where I should have used a 100 Ohm resistor for the display I'm using and I burned out the back-light. That's $40 down the drain and I'll have to wait for another display to be delivered.

Oh well, lesson learned.

SJ_Digriz · Post by **SJ_Digriz** » Fri Aug 01, 2014 7:54 pm

Welcome to DIY .. wait till you build off a half assed hand written and scanned quasi complete schematic, only to find out that many of the markings are incorrect because the author transcribed the from a different voltage... after getting about 90% through. If you survive that, you are doomed to DIY forever.

justin3am's Mutable Instruments Ambika build now w/sound!