My first DIY

[b3groover]

First off, I'd like to say that this forum is downright invaluable and everyone here is as nice as can be. I have not contributed much since I am an electronics novice, but I really appreciate everyone's knowledge and helpfullness here.

Now for my project:

I bought some MAP preamp cards from fellow Group DIY member Tungstengruvsten. From what I've read (on here I believe), MAP or Modular Audio Projects eventually became Melcor and then API through various ways and means.

Anyway, the case is an old Carvin power amp that blew up several years ago. I always intended to fix it but then found that the mosfets were fried and they are expensive. It was actually more cost effective for me to buy another, non-fan cooled amp, but I held on to the Carvin thinking I might be able to use it. Lo and behold, here 'tis!

I plan on painting the face some wacky color (suggestions?) and using those rub on letters for the switches and dials. Here's the real cool part: The knobs and pots are from the Carvin amp and just happened to be 40-step 10k audio taper pots!! They work perfectly with the MAP cards.

I used JLMAudio's JLML5RPSPCB power supply kit, which gives two rails of +/- 5vdc-30vdc and 48vdc for phantom. It's a real nice little kit. Highly recommended... and Joe is very nice.

The reason I put the XLR inputs so close to the power supply is that unfortunately that's where holes already were on the Carvin and I don't have the tools yet to drill large holes in metal. So far I don't have any hum, so I consider myself lucky!

I just bought some of rlauy's Phantom/Phase/Pad PCBs since these MAPs definately need pads. They have plenty of gain!

Anyway, it's whisper quiet (no hum) and sounds great. I've already used it to track harmonica using a Rode NTK and the track sat in the mix perfectly without any EQ.

This gives me confidence to start populating Peter's Green PCBs I just got and the SSL clone PCBs I got from Gustav awhile ago! Woo hoo!

Little Zora gives her approval!!

 

[soundguy]

hey dude-

looks cool! Do you have a power drill? A great trick I picked up along the way is using a power drill to wind the loose wire pairs in the chasis, just put the wires in the chuck and twist and you get a really professional looking and easy to dress cable assembly coming off your edge connectors, try it for your next project!

Box looks great, you'll have to let us know how your snare drums sound through those!

dave

 

[b3groover]

Dave,

The drill idea is a good one, thanks! I'll definately do that next time around. See, you guys have all the tricks!

I will try snare drum when I get the pads installed. I've heard these are really good on drums. In fact, the first thing I tried after getting them up and running was using them on drum overheads with a pair of MXL 603s (which have hot outputs to begin with) and quickly realized that pads are a must!

What color should I paint the face? I was thinking red.

 

[owel]

Congrats on your new preamp!

And I bet that cute baby girl is the best DIY project you've ever had

 

[b3groover]

[quote author="owel"]Congrats on your new preamp!

And I bet that cute baby girl is the best DIY project you've ever had [/quote]

She is a dream, but she wasn't exactly DIY....

 

[jrmintz]

Very nice job b3groover. I have a couple of Shure inline switchable pads. They're very handy for this sort of use.

And that's a lovely kid. Enjoy her - they really do grow up too quickly.

:thumb: :thumb:

 

[PRR]

> A great trick I picked up along the way is using a power drill to wind the loose wire pairs in the chassis, just put the wires in the chuck and twist

POWER drill??? All my life I've done it (both wires and DIY rope) with hand-drills. Rope-making begs for power, but I've never wanted power-help for twisting wires. I just re-did my doorbell with hand-twisted-pair, and the winding is quicker than plugging-in a power drill.

Or do some of you guys not even own a hand-drill? What's the world coming to?

One thing the power-drill is good for is faking XLR holes in Aluminum without the proper tool. Clamp a hardwood block on both sides. Use a low-price spade-bit of the right size. Assuming everybody has a power drill, a cheapo spade-bit is only $5, and while made for wood will drill a couple dozen holes in aluminum before it goes sour. Just go REAL easy as it breaks-through the metal: it will want to break your wrist when it grabs. The harder the wood in the back-up block, the less it grabs.

B3: very sweet synergy. What's wrong with business-like black?

And BTW: if you have any more dead power-amps, National's "OverTure" power-amp chips can replace dead-discrete output stages up to +/-40V and about 60 Watts for under $10.

 

[alk509]

[quote author="PRR"]Or do some of you guys not even own a hand-drill?[/quote]

Since I don't own a hand drill, I thought the above was funny, so I read it to my wife... Her answer:

- Own one??? I don't think I've ever even seen one!

So that right there implies at least 20-something years of obsolescence, PRR... step into the 80's, man!!!

:green:

Peace,
Al.

 

[Kev]

Variable speed , variable clutch reversing BATTERY Drill

I have a few of them and they get used more than any other power tool ... including the Soldering Iron ... :shock:

 

[PRR]

> - Own one??? I don't think I've ever even seen one!

The USA classic hand-drill.

The Miller #2 and #5 (or no-name clones) were in EVERY craftsman's box.

While antique buyers snap them up for decorating, you can still find these drills in garage sales.

The #2 and #5 are frankly pre-electricity models. You can do heavy work with them, if you have to. But note the #4, which would be a great electronics tool for PCB and small Aluminum, even if you have the big-mutha power-drill (or a #2/#5) around.

I think Millers Falls got killed by cheap copies. You can buy chinese hand drills in most hardware stores. Some are pretty crappy, give hand-drilling a bad rap. One model I do like (though not for list price) is the Fiskars.

The bits that come with it are a joke. Use good bits, and don't use dull bits. Even in a power drill, the differences between a blunt bit, a cheap bit, and a good bit are large. By-hand, a good bit is a dream and a bad bit is a never-ending nightmare.

 

[MikoKensington]

I own a hand drill! But it's totally seized. Liquid wrench. WD-40. Dura Lube. Nothing can free it. It was my grandpa's. :grin: Perfect for old farts. :wink:

 

[tony dB]

Hi b3groover,

Big up for your first diy !
glad to see you've been bitten by the bug too :grin:

Good luck on future projects;

Tony.

 

[peter purpose]

Top job b3g..... :thumb: feels good hunh?

My trusty hand drill.... yes, I am a hundred.

 

[Guest]

Last person I saw use a handdrill was my grandad in the 1970s... - and he was born in 1890
Nice first project - your box is a lot neater than my first one...
Are you worried about the mains transformer inputs into the green terminals on your PSU PCB coming free?
I am for mine and wondering how you have done it....

(oh - lovely daughter )

 

[kent]

Big thumbs up on your first box. I like reusing old chassis too! Environmentally conscious audio!

cheers,
kent

 

[b3groover]

[quote author="uk03878"]
Are you worried about the mains transformer inputs into the green terminals on your PSU PCB coming free?
I am for mine and wondering how you have done it....

(oh - lovely daughter )[/quote]

Thanks for the compliments. Zora is a little sweetheart.

I am not too worried about the transformer leads coming loose. The screw terminals seem to hold them in very well. Just to make sure, I did tin the leads quite a bit, so that they were thicker.

I can't wait to get started on the Green pre's and the SSL. Gotta save up a little $$ for some nice Par Metal cases!

 

[fazeka]

Don't worry, Paul. I hear ya, brother.

Sometimes I need to drill something, not a big project, just a bleedin' little hole and I get lazy having to go into the house and pull out my ol' Milwaukee electric corded :shock: (soon that will be 'antiquated' too, I'm afraid) and *plug* it into the wall. My dad used to use one of those Stanley augers that you would push on to get the shaft to rotate and it would dig in and drill your hole... I miss that tool for quick and dirty holes.

I don't care *what* anyone says, the glory years of most hand tools are over. Y'all can take the new stuff, give me some ol' Craftsman and SnapOn tools anyday.

 

[soundguy]

omg PRR, you can shoot signal from your finger tips and you have a hand drill! My dad used to have one of those and one time I saw a drawing of one on the inside of a cave... I have a varispeed battery dewalt which has never been a problem. The nice thing about it, which maybe you could do with a hand drill, but it much easier with a faster speed- I'll put one end of the wires to be bundled in a vice, pull out maybe 20 feet of wire, stand across the room with the drill and twist it all and just keep that in a roll on the bench, that way I never have to twist them inside the chasis, always have some pretwised to go. Twisting 4 wires or more is definitely the stuff of power drill.

dave

 

[Nutts]

For god's sakes don't paint the thing!!! It looks too cool all beat up and dusty. Hope it sounds great and that you can hand it down to that budding engineer you've got there.

Tom

 

[b3groover]

No paint?! Hmmm.... see here's the rub... the front face is flipped. On the other side is all the Carvin silk-screening including numbers for the pots. My plan was to tape circles over the numbers so that they will be preserved, and then spray paint the rest of the face.

It does look kinda cool all beat up, though. Hey, it's "vintage"!