What have you DIYed lately?

[Jim Williams]

[quote="dfurutaYes, the best test gear has limitations and sometimes you are right up against them. Someday there may be better tools but so far this is it.[/quote]

I'm obviously less knowledgeable about this stuff than you, but doesn't measuring with a shorted input understate the noise current contribution? Or, is that low enough at microphone impedance that it can be ignored?

Either way, the NF at 50 ohms of <2dB is rather nice![/quote]

Noise is accumulative. Any mic preamp that doesn't lower it's self noise below a 150 ohm source contribution is adding that addtional noise to the mix. It also shows a lower noise floor at lower gains where many preamps fall short, they are dependent on high gain of +60 dbu to measure that 150 ohm noise spec when at +40 db gains, their background noise is proportionally higher.

If you use a very quiet condenser mic with high output, the signal to noise ratio is much improved at gains around 40 db or so compared to traditional transformer input mic preamps that offer that -128 dbu EIN only at +60 db of gain, it falls off below that. 50 ohm low output ribbon mics also benefit from this technology as you can obtain that extra gain needed without that extra noise contribution.

To obtain what I call "digital black" I use these specially built mics with extremely low noise rf transistors. There is also only one very high quality film cap in the signal path, far less that any other condenser mics I know of. That feeds those preamps idealized for that 50 ohm source impedance.

With this system there is no hiss heard nor printed. Crank up the gain on a track and all you hear is room air noise, that random air noise in a quiet room. Pull the faders back (I use an analog console with similar design perameters) and no noise is ever heard, there are black spaces between the notes. When using this stuff in other rooms I usually have problems hearing the air conditioning, for acoustic recording that usually must also be shut off during recording.

40 years ago I had crappy recording gear and fantastic artists to record.

Now I have fantastic recording gear and crappy artists to record.

[getreel]

40 years ago I had crappy recording gear and fantastic artists to record.

Now I have fantastic recording gear and crappy artists to record.

You know what..I totally believe you.

[germaniac]

Recently went through my Sound Workshop 242A and replaced all the electrolytic caps, upgraded mylar caps with polypropylene, added PS de-coupling caps to all op amps, bypassed PS caps with film caps, replaced 4558 op amps with better. Sounds very nice now, but still must be mounted four spaces away from anything else in the rack due to the spring pan xfrmr hum. When is somebody going to start making spring pans with humbucking xfrmrs?

Also been cleaning a lot of vinyl record with Elmer's Glue-all. Results are really incredible, especially if the record is otherwise free of scratches.

Joe

[dfuruta]

Also been cleaning a lot of vinyl record with Elmer's Glue-all. Results are really incredible, especially if the record is free of scratches.

http://aurisapothecary.org/AAX-019.html

[germaniac]

http://aurisapothecary.org/AAX-019.html

Yeah, we used to do that all the time. . . .











( )

[Jim Williams]

When is somebody going to start making spring pans with humbucking xfrmrs?

Also been cleaning a lot of vinyl record with Elmer's Glue-all. Results are really incredible, especially if the record is otherwise free of scratches.

Joe

Just don't leave those coated records on a piece of furnature or that will also be picked up.

Over 30 years ago I had Accutronics, the spring reverb folks custom make me a set of reverb springs with counter polarized coils on one unit. I would use 2 tanks, wired in series. The drive coils were wired reversed polarity on one coil. That cancelled much of the fundemental tones that cause the "sprong" sounds.

The recovery coils were wired in series, out of phase to create a humcancelling pickup design. Accutronics reversed the magnet polarity so that would work. I got an 80 db S/N ratio out of that design back in 1981. If you contact them they will still do this for low cost. I used the type 9 3 spring models, good results can also be had with the smaller 3 spring type 8 tanks.

That design then fed a custom one knob expander/compressor circuit. With that I could "adjust" the reverb times. The whole rig worked so well many though I used plates. Even Doug Sax, my mastering guy in those days was extremely impressed by it and all the custom recorded stuff I brought to his room.

[Jim Williams]

40 years ago I had crappy recording gear and fantastic artists to record.

Now I have fantastic recording gear and crappy artists to record.

You know what..I totally believe you.

You know, I suspect I'm not the only one with this problem.

[dfuruta]

Hey, a lot of us have crappy gear and crappy artists (ourselves, even)!

[Glory_Morris]

For some sessions out of town, I DIY'ed a Mic Preamp with Tone-Balance and Low Order Harmonic Distortion generator and an Optical Compressor:

http://glorytron.com/2012/12/vocal-sess ... -diy-gear/


Also, I built a thing called the Sync-Mode Monitor to deal with monitoring latency, but I've started a separate thread about that:

http://glorytron.com/2012/12/a-bit-abou ... e-monitor/

[germaniac]

When is somebody going to start making spring pans with humbucking xfrmrs?

Also been cleaning a lot of vinyl record with Elmer's Glue-all. Results are really incredible, especially if the record is otherwise free of scratches.

Joe

Just don't leave those coated records on a piece of furnature or that will also be picked up.

Interior Innovations Incorporated. But seriously folks, for anybody who enjoys listening to vinyl at all, it's like restoring the record to brand new, notwithstanding scratches or wear. Lots of vids on YouTube. BTW, plain old Elmer's works best IMO.

Over 30 years ago I had Accutronics, the spring reverb folks custom make me a set of reverb springs with counter polarized coils on one unit. I would use 2 tanks, wired in series. The drive coils were wired reversed polarity on one coil. That cancelled much of the fundemental tones that cause the "sprong" sounds.

The recovery coils were wired in series, out of phase to create a humcancelling pickup design. Accutronics reversed the magnet polarity so that would work. I got an 80 db S/N ratio out of that design back in 1981. If you contact them they will still do this for low cost. I used the type 9 3 spring models, good results can also be had with the smaller 3 spring type 8 tanks.

Thanks for this Jim. I'm familiar with that approach from previous posts of yours and some other sources, but haven't worked up the head of steam to tackle it yet. It still leaves me wondering though, why doesn't Accutronics (or somebody) make humbucking input/output coils as standard by now? Maybe the answer is because the market for most springs is guitar amps, where the performance isn't exactly critical. . . .

Joe

[Jim Williams]

Residual noise in a guitar amp usually masks the reverb return coil hum pickup as the reverb mix is usually below the dry signal by quite a bit.

The coil forms are molded mylar. They are already pretty small so fitting a pair in there would be tough and would require an entire re-design of the drive/pickup coil, magnet rods and core. So there is really no economical way or reason for them to do that, folks that want quiet, quality reverbs buy Bricasti's, not spring reverbs. 99% are sold to guitar amp makers anyway, so they don't care much about pro audio. At least they will do custom work for you, most will not.

Personally, I would rip it out and wire in some send and return jacks and patch in a low cost Lexicon. I have no more springs around here, not in my old Fender amps nor the control room. All the amps have tube loops in them too so I can still patch a spring reverb in if I want to. Usually it's a lexicon patched in.

[Brett Siler]

The big project I've been working on rewiring and reorganizing my patchbays and rack gear. Man what a man in the ass.. ha! I'm almost done, tonight should be the last night of it. I'm taking a break right now from it.

Earlier tonight with the help from my lovely girlfriend we re-ribboned a two MXL R40 ribbon mics. I got it on sale for $70 bucks each! I figured, why not? When I first got the mics I was just checking for ribbon sag and accitdentally ripped the ribbon! So I found a sheet of 2.5u aluminum foil, and a crimper thingie on ebay and got to work. After several stressful failed attepts we finally reribboned them! The foil is sooo delicate it which made for a very stressful 30 minutes or hour or however long it took.
Other mods I did to it were put some RVT caulking inside the body too damping the bodying ringing and ripped out a layer of mesh in the head basket for less resonance. I may swap out the tranny in the near future when I have more money.

All in all it sounds pretty cool! Very dark. I'm looking forward to putting it through it's paces

[dfuruta]

Earlier tonight with the help from my lovely girlfriend we re-ribboned a two MXL R40 ribbon mics. I got it on sale for $70 bucks each! I figured, why not? When I first got the mics I was just checking for ribbon sag and accitdentally ripped the ribbon! So I found a sheet of 2.5u aluminum foil, and a crimper thingie on ebay and got to work. After several stressful failed attepts we finally reribboned them! The foil is sooo delicate it which made for a very stressful 30 minutes or hour or however long it took.

Very cool! Any chance you could share more details about the process (how you corrugated it, where you got the material, any problems you had to solve to install the ribbon)?

This is one of those things I've been curious about but haven't worked up the gumption yet to try.

[getreel]

Still working on the little Alice 828 mixer. It turned out to be such a simple design, it was fairly easy to get it going even though it had been butchered a lot over the years. All channels, power supply, and master section rebuilt and recapped. Just need to finish installing the new copper bus bars and then give it a good run through. Wish me luck!

[Brett Siler]

Earlier tonight with the help from my lovely girlfriend we re-ribboned a two MXL R40 ribbon mics. I got it on sale for $70 bucks each! I figured, why not? When I first got the mics I was just checking for ribbon sag and accitdentally ripped the ribbon! So I found a sheet of 2.5u aluminum foil, and a crimper thingie on ebay and got to work. After several stressful failed attepts we finally reribboned them! The foil is sooo delicate it which made for a very stressful 30 minutes or hour or however long it took.

Very cool! Any chance you could share more details about the process (how you corrugated it, where you got the material, any problems you had to solve to install the ribbon)?

This is one of those things I've been curious about but haven't worked up the gumption yet to try.

Yeah of course! Maybe I should start a thread for it...