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SCA 35 success!

The saga is complete... for now. Got the new transformer from Triode and wired it back in the other day - still working like a charm and no more hummm. It's great to have a working phono section again so I can listen to yummy vinyl.

The SCA has a Tape Out channel so next I'm going to send that thru a pre-amp to my ST-35 and power some remote speakers. And so begins my quest for a fuse holder that will fit the ST-35...


Mon amour Monome?

I think I'm in love.

Currently hand-made and available only from moname.org, this USB powered control surface is a completely programmable device meant to be used with music control programs such as Max/MSP, Pd, and other MIDI, OSC etc music control languages. The website features free application software to run the device, as well, which does not require the purchase of Max/MSP, so there are no hidden costs until you start to get into really programming this as an interactive device. The website seems quite active and there are already quite a few OpenSource programs for the monome available there.

Downside is it's $500, and it's not standalone, it requires a computer (though the potential exists to build a microcontroller interface). Upside is the software allows you to program the lights independently of the the keypress reader - so they're not just toggles. It is also a multi-touch controller, which allows for much more sophisticated interaction than a touchscreen. The software could for instance wait for the third press of a key, a sequence or pattern, then draw a sequence somewhere else on the board, or start a loop, or a video. People are already writing interfaces to Abelton Live and other popular music software. The possibilities are truly limitless. The video hints at some these:



Dynaco SCA-35 update

I installed the new power transformer in the SCA-35 and got everything wired back up and at first was really psyched to listen to some vinyl again. After a couple of records, though, it became apparent that the new transformer was humming loudly, without too much detectable vibration. There was also a slightly softer hum through the speakers which sounded like maybe a little ground hum. But since everything else was the same but the transformer (previously raided to get my ST-35 power amp going), and I had triple-checked my wiring, the tech at Triode suggested I send it back for a replacement.

I pulled the new trans out and on a whim I installed the xformer that I'd originally pulled out of the ST-35 . Sure enough the fuse blew immediately. Oh, well.

I guess now I could pull the original one back out of the ST-35. The St-35 needs the PC boards re-done anyways - the plastic tube sockets have gotten melty over the years, and the boards are visibly darkened & warped from the tube heat over the years. I have a pair of new brand PC boards sitting in a drawer all ready to go - but I'll need to order new new ceramic sockets and components for that project.

Forced to use what I have on hand, I may just go ahead with the xformer transplant. I recently got my Hafler DH-220 going again so I guess I can spare the ST-35. If the result is being able to listen to some vinyl through the Dynaco's sweet phono section later today I guess it's worth it.

Also, my friend Dave gave me a sweet Bogen gold-face integrated the other day, model AP-30. The phono section is real thin for some reason. I did some tube rolling but no change. It sounds great through the Aux channel, though, very up-front and warm through my EPIs. Hard to adjust the volume at the lower end of the range, though - it begins to crackle and lose balance. This seems to be something that frequently goes wrong with the old amplifiers as the old pots age. It makes sense since the dirt probably builds up most at the end of the wiper face. These early stereo amps often use a ganged (dual) potentiometer which can be expensive to replace and usually involves some tricky soldering.



Dynaco SCA-35 resurrection

So I hauled out my Dynaco SCA-35 the other day. I had raided it for parts awhile back: stole the power transformer for my ST-35, and a couple of big resistors from the rectifier / filter circuit. Been gathering dust ever since.

I finally found a replacement transformer from Triode Electronics and now I'm putting it back together and am thankful I found these:




...which contain detailed wiring layouts, schematics, and an actual photo of the completed bottom of the circuit board which is what I really need to figure out how this goes back together.

Note: If the above links go away I archived them here:






Series vs. Parallel Wiring

A good article on wiring speakers by Wayne Harris



Clarion / c-bus / iPod / Saab NG900

This isn't really about tubes but it is definitely part of my quest for good sound on the cheap.

I went on my first real adventure in car audio when I installed a pair of vintage 12" tri-axial EV speakers into my '66 Barracuda last summer, but that's a story for another time...

Back to our hero:

My wife and I just purchased 2 used Saab 900's, and I have been busily pimping both rides on my lunch hour and after dinner.

Part of our buying spree (btw: just so no-one thinks we're rich or anything, we actually saved a bunch of money by buying 2 high-mile 90's Saabs - spending 1/2 of what we had budgeted for a new Mazda3, and I'm pretty sure we both got much better cars as a result plus lower payments and insurance...) involved the purchase of a pair of iPods.

The simplest in-car iPod solution is, of course, to go out and buy a $99-140 head unit with an Aux In jack in front, plus a 1/8" stereo cable to hook the iPod to the jack through it's headphone output. Which is what I did for my own car at first, while my wife used a cassette adapter with her factory radio.

I borrowed her car, and I really liked the sound and adjustability of her factory Clarion cassette/radio. It also integrates nicely with the dash (of course) and the SID (System Information Display). The sound is decent, with tight low end and reasonable highs with surprisingly good imaging even though the door speakers are not installed in her car. But the iPod via cassette adapter interface was significantly bad, and in examining the cassette adapter it was obvious the record head was worn and grungy and something was peeling off... also, it's possible the ipod's headphone output doesn't send a strong enough signal (argument towards the Belkin car-lighter adapter).

So she was getting alternately awesome sound when she listened to the radio and crappy tinny sound when she used her iPod. No wonder she kept leaving the ipod home!

I've never liked the whole cassette adapter thing - it seems like such a primitive way to transmit audio: e.g. send it through 2 sets of magnetic heads that are pressed together while a motor whirs away doing nothing. Assuming you get good contact between the tape heads and adapter you can get decent sound. But tape decks are finicky creatures at best. A lot of variables can affect the sound: the way the tape blank is inserted in the deck, are the play heads in the right place, is everything clean... lots of places to degrade the heck out of the signal. ... or maybe it'll add some of that "tape warmth" everyone's gotta have... I'll follow up on that tangent later.

Anyways, I went down the easy path and bought a mid-level Sony head-unit with Aux In on the face and off I went. Within a day I realized the sound in my car was somewhat anemic compared to my wife's car. So I added an Alpine amplifier and a 10" subwoofer in the trunk. Wow! Huge difference, but still something was missing. My door speakers weren't working, the amp to run them is gone. So I ordered a factory head unit off eBay and a slave amp for the door speakers.

Now, there is no Aux In on the factory Clarion cassette radio for 93-98 Saab 900's, but there IS a 13 pin DIN-type CD Changer jack in the rear of the Saab head unit.

It's called a "c-bus" interface and it looks like this (round one on the left - the rectangular ones are the main harness):

Here's the pinout:

(image from: http://www.mictronics.de/?page=cdc_proto#Clarion)

There's also a round output on the side to connect it to a booster amp for the door speakers. I found the amp on eBay but I still need to find (or make) the right cable to connect it to the head unit.

I've found it difficult to source the main head-unit after-market harness anywhere but the specific Saab aftermarket. This seems weird as I'm pretty sure it's the same thing that came in a lot of GM's at the time. Will investigate further (would be nice to have a handy nearby junkyard).

After 1998 they went with a new architecture called ceNet or something which has a square connector (also 13-pin I believe) and it does computer stuff.

Clarion makes an adapter for $100 which lets you run an old C-bus CD Changer with a new ceNet head-unit, but not vicey versy. There is surely some obscure legal or marketing or just plain ornery reason they're not making an adaptor that lets you just use your old c-bus head-unit with an iPod (or new CD-Changer - as-if) but for the life of me I can't figure it out. Just about every other auto maker in the Universe has a product available on the aftermarket for $59-$99. I think it has to do with the juggling leadership of of GM/Saab/Chrysler/Daimler/Benz - but somewhere in there the 1994-1998 head units got orphaned. I also suspect that "cbus" being a proprietary protocol has something to do with it.

I've searched the internet high and low, using the terms in the title of this post, and more, with very little luck. One guy soldered wires to the circuit board of his factory CD head unit but it requires you to have a blank CD running all the time (whirrrrr). He to0ok just the audio signal off the board, none of the control info. Various similar approaches here:


This guy here describes building a cable by taking apart a Belkin adapter:


The only good solution, as far as I am concerned, would be a cable with a c-bus DIN connector at one end, and an iPod data/power cable at the other. Switch the head unit to to CD changer mode, and you're listening tothe iPod. If necessary, stick a gronker in the middle to fake out the head unit - sending a certain voltage down a wire or whatever. How hard could it be?

Stay tuned to find out!!!

Update: Sunday, May 28, with actual sunshine

Okay, so now I have lots of wires and an extra head unit and a free afternoon...

let's see if I can cook something up...

http://www.mitt-eget.com/saab/faq_electrical.shtml (good info for fixing the SID's, later)

CD Changer NG900 FAQ

I went to Best Buy and picked up an adaptor for a Kenwood stereo, since it also uses a 13-pin din connector. Then I found this on the internet:


This guy is hooking up a Kenwood head unit to an iPod. He wires up the 3 audio leads to RCAs then puts a 10K resistor across pins 3 and 9 and this fools the Kenwood into thinking the CD changer is running. Then you send it iPod audio through the RCAs.

Here's some more info, from a VW :

Connect pins 5 and 9 together via a switch (on, means a logical +12V signal appears on the 'slave on' pin hence switching the head unit over to CBus input as it thinks a CD changer mag is present).Then simply connect the Left, right and gnd pins to the appropriate RCA's and you should have yourself one CBus - RCA converter for clarion.

So now I'm hoping a similar trick will work for my Clarion. But since a $20 adaptor already doesn't exist for this application, methinks there's maybe a reason: e.g. I'll need to send some sort of data down the wire and a little resistor magic just ain't gonna do the trick. Maybe it'll need to be a real extra-shiny gronker to be able to fake the Clarion out...


This guy is definitely onto something, but his solution seems to require you to have an actual CD changer running all the time:


Update 4/25/2007: Well it turns out the CBUS option won't work (for me anyways) because it requires data to be sent down the wire. I suppose if I had a CD changer available and TONS of spare time I could try to intercept the data, figure out what it is, and build a gronker to fake out the headunit... instead I am going this direction:


(very nice step-by-step instructions for adding a line input by soldering a connection internally to the tape connections, then using a switch on the tape door to enable/disable)


Crookes Y Tube:




2 cool sites





Warmth - what is it? How do you get it?

Interesting article by David Mellor that explains tube and tape "warmth" - fact or fiction?

His website has articles on a variety of topics of interest:




The more I closely I listen to sounds and music, the more I notice environmental noise. My house, especially, is very noisy. The fridge hums, the furnace rumbles, the TV hums, the electric heaters hum, the dishwasher sounds like two cats in a dryer, and most of all, the computers hum and bubble as drives are accessed repeatedly for no apparent reason, as update after update loads surreptitiously each night, hard drives busily grawing and nibbling their way full,. And hard-drives live dangerous lives, forever perched on the brink of sudden drive death, trembling with every clap of thunder and cringing from every brown-out. And the phone rings with spam calls all. day. long. I mean, it's not like I'm asking too much to be able to type into my sleek little gizmo where ithout listening to an orchestra of buzzing and chirping and ringing?




Tel-Ray fluid

I got this e-mail today:

You contacted me about obtaining oil for the Tel-Ray memory cans. It is called Ucon LB-65. My contact is Jim Rutledge. He can sell enough for two machines. It only takes about two tablespoons. He wants about $25 payable by check. Contact him for details: rutledge@fayelectric.com I hope this works out for you!

Slightly ironic as I just sold my Tel-Ray on eBay.






Good audio site

Has some good diy projects and illustrations of acoustic room treatments




Balance & Unbalance

Connecting balanced and unbalanced equipment:




How to wire an XLR to an RCA connector




It's Only Superposition

Superposition of Waves = cool animations and explanation of phase cancellation and harmonics.



Science and Subjectivism in Audio

Science and Subjectivism in Audio



Neve mods, tips, tricks

Phoenix Audio Technical Tips, Tricks and Secret Bits Pages




An Improved Method of Audio Level Control for Broadcasting and Recording

by James F Lawrence, jr.
(From the Journal of SMPTE Volume 73, August 1964)



How to build a tube Compressor/Limiter




Neve kits, info, links


Group DIY: http://recording.org/users/kev/Project1.htm

FET PreAmp: http://www.till.com/articles/GuitarPreamp/index.html


Neve Stories





Gain Control Devices, Detectors, Side Chains & Audio "make-up" Amplifiers
by Eddie Ciletti and David Hill


LA-4 mods

Simplified LA-4 Modification, Upgrade and Parts Options
by Eddie Ciletti

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