February DIY Challenge!

  • Thread starter Thread starter mshilarious
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mshilarious

mshilarious

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OK, so I see on Songwriting that there is a challenge to record a CD in February. For many reasons (more than a few of them related to DIY), I won't be able to do that to any reasonable level of quality, so instead, a challenge just for us!

It's simple: complete one DIY project in February, post pictures, audio samples, schematics, whatever you got! :)

I have sketched out a list of projects I am hoping to finish:

- surround speakers using Fostex full-range drivers
- a couple of RCA - XLR baluns
- the first stage of my pending class A MOSFET guitar amp - this will be a little small amp using an 18VDC power supply, as a development project for a much more exciting TBA project :)
- a microphone meter/test box
- a new, internal PSU for my MIDI controller with a dead wall wart
- the LED flasher circuit for my Epi Airscreamer
- bottom heads for the toms on my Pearl Rhythm Traveler kit


Ambitious, yes . . . but if I can do even one project, then you can too! :)
 
Dude, I got tired just reading your list.:D I just finished organizing my cables today so I feel like I have one project in the bag. I also want to build a new rack that will be a little more road friendly and allow me to safely take my rig to gigs and record live.
 
resolder my alligator clip leads :D

try out some different capacitors in my ACM-900

somehow get in touch with ART support so they can sell me a replacement main board for my Digital MPA that I hosed on my last DIY project :D
 
I'm game. Here's my hit list:

1- Finish the console and tape machine stand plus a 2 bay rack
2- Build 7 mic pre's, power supply, and mod 2 rack cage's for them
3- Rack 2 more mic pre's
4- Biuld 2/3 active direct boxes
5- Build 2/3 passave direct boxes
6- Build 2 Paia kits
7- Wire 16 track analog project studio
8- Chill

I just got put on 12 hour work days. This should be real interesting.:o
 
Went like "gang busters" all week on the wood projects till Sunday night. Worked 15 hours Monday then it got to cold to work in the garage. I'm in the process of number 8 tonight but I should get off my duff and make a parts list for the pre's and get a little foward "indoor" motion.:rolleyes:
 
mshilarious said:
My list is easier than it sounds. gerard's list scares me :o I also have a preamp project, but there is a 0% chance I can get to it this month :(
Click to expand...


Yeah, you seem kind of lazy compared to gerard.:D
Compared to you it must seem like I'm in a coma. I have been working real hard on #8 from gerard's list.:o
 
shoot, forgot #9 & 10

9- Stereo splitter box for my bass
10- Simple headphone/cue system

When I really get board, I'll replace the power supply in my SPX 90II. It works fine but my friend has a update that makes it....well...gooder:D
 
You said "complete," so hopefully we can include things we started but left off on.....

1. Finish dual 1176revD clone.
2. Finish 2 BabyAnimal mic preamps, 1 API312-ish, and 1 Dual BA with Lundahl LL1538 input xfmr and FETBloke discrete opamps.
3. Finish Gyraf headphone amp.
4. Mod Blehringer ADA8000; bypass input balancing stage to ADC, possibly use single 2SK170BL FET as balancing stage (based on a DI design). Test OPA2134 and MC33078 in output driver stage.
5. Build DIY990 discrete opamps, install in mic preamps.

Weirdly, that doesn't seem like much. Listing it out like this made it look manageable.

This thread is motivational. Thanks!
 
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skipwave said:
4. Mod Blehringer ADA8000; bypass input balancing stage to ADC, possibly use single 2SK170BL FET as balancing stage (based on a DI design).
Click to expand...

You lost me there. Isn't the input stage differential? Is the AD chip? Why a FET? You'll need to get that biased properly while managing a fairly high signal level. AD inputs are supposed to want to see really low source impedances, I am not sure 2SK170 qualifies, although it might, you'd have to check the (Wavefront, I think?) datasheet. Overall, I think you will have a really tough time beating a good opamp, and even if you somehow do, you're still feeding an 8 year old AD converter chip with it.

Personally, I think the best ADA8000 mod is to buy an Alesis AI3 . . .
 
OK, I had a peek at the datasheet. I guess a single transistor as phase-splitter would work (the chip doesn't seem to care much about source impedance, I guess since it's not particularly low noise), but . . . at 8V peak to peak, I think you might not get the best distortion performance . . . but again, don't you want a balanced input :confused:
 
I'm wanting unbalanced input, since I intend to use all outboard preamps in front of it. I've built most of my mic preamps with switching jacks for unbalanced or transformer balanced output, and often times the unbalanced out sounds more appropriate to me.

The simplest approach is to bypass the input transistor pairs, and go straight to the differential inputs of the TL071. That got me thinking if I could accomplish the same with a single active element phase splitter, maybe that'd be something.

Interesting about the AI3, it looks awful similar.....

http://www.blacklionaudio.com/AI3.html

http://www.kellyindustries.com/computer/alesis_ai3.html
 
skipwave said:
I'm wanting unbalanced input, since I intend to use all outboard preamps in front of it. I've built most of my mic preamps with switching jacks for unbalanced or transformer balanced output, and often times the unbalanced out sounds more appropriate to me.

The simplest approach is to bypass the input transistor pairs, and go straight to the differential inputs of the TL071. That got me thinking if I could accomplish the same with a single active element phase splitter, maybe that'd be something.
Click to expand...

The input transistor pairs in front of TL071 would be to improve the noise performance of the front-end, but that only matters in a mic-amp application.

You can bypass the opamp, but by that token, you can also run the AD chip unbalanced by referencing its inverting input to its MOD pin. I just don't think you'll get the same low distortion out of a single FET vs. an opamp, and I don't think you'll gain much with 1" of a balanced circuit when the 10' before it is unbalanced.

Personally, I strive to make all connections balanced, but that is somewhat of a necessity in the EMI hell that is my house. Transformers are perfectly happy doing either one, so if you prefer unbalanced, maybe you just don't like the sound of that transformer :confused:

Interesting about the AI3, it looks awful similar.....
Click to expand...

Its uses the same AD chip, which is/was an Alesis product . . . I forgot if they spun off Wavefront, or what, but they are related. Does Black Lion want $300 to swap out a few opamps? Ouch.
 
My goal is to build a new pedalboard, but I need some help figuring out how to get what I want. I have a Whammy on one end and a talkbox on the other with three normal-sized pedals in the middle. I've noticed that they add some noise (hiss) to the guitar signal, so I would like to get around that if possible. I need two be able to plug in up to three different adapters (the talkbox and whammy both use AC, but I don't have a daisy chain, and the other use a 1-spot DC adapter). So I guess what I want is to attach an outlet strip hidden somewhere underneath or something and I need to have access to the Whammy and talkbox pedals, but the others could hide somewhere if bypass switches would help get rid of the noise. I'd still want to have access to the knobs, though. I also have a Vox Wah I'd like to put in the chain, so I'd need access to that, too. Although I never use it... maybe I should just sell it. Anyway... suggestions?
 
I'm new here. If I am recycling old threads, please forgive......But,
After reading a recent post on this "DIY" forum, I have been ....aaaahhhh, blown away with the fact that a Leslie style guitar speaker is buildable from materials found at your local Hardware store. (except for the speaker itself). After doing some research on this,
I accept the MSH February DIY Challenge! Hopefully, There will be at least a couple other members that can collaberate on this project. I found a very interesting site on the history of the "Leslie Style speaker" for guitar, that has some pictures for reference purposes. Way more info than I ever knew existed and some additional links.

http://www.nmia.com/~vrbass/vibratone/

First thing I gotta do is figure out ........Who borrowed my Table Saw........

This is gonna take some mechanical engineering.......and some insight!

Very Do-able! Thanks for the PUSH, MSH!
 
I just etched 8 PCB"s for my active guitar electronics design...I"m going to build a few and give them out to a few guitarist friends to see what they think and what improvements I can do as I was thinking if I get a good responce I might try selling them...I just need to get some stereo 1/4 jacks and try to find some small plastic cases about 1 in x 1.75in and 1/2 in tall to put the curcuit in.....
I have them installed in all my guitars and they sound freaking awesome especially if you have a tube amp and like heavey tones....

Cheers
 
thebigcheese said:
if bypass switches would help get rid of the noise.
Click to expand...

The Loop Switcher I mentioned in the post above is just that impedance converter in front of a DPDT stomp switch, for when I want to bypass all the pedals and go straight to the amp. Instantly eliminates any noise contributed by daisy chained, buffered pedals.
 
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