Who wants to help me figure these bad boys out?

[MikoKensington]

So I don't know if this was the most wise move. But Voila...

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3727252220&sspagename=STRK:MEWN:IT&rd=1

Anyone want to help? I'll send you a single and a dual. :thumb:


:guinness: :sam:

 

[CJ]

Holy crap Batman, thats 84 channels!
Thats only 5 bucks a channel!
Score!
Black Market, here I come!

Hey Miko, what kind of keyboard is that on those old Detroit acid house stuff, sounds kind of like a cross between a Rhodes and a Hammond?
They use the same box on just about everything back then.


Sorry for the OT.

Let us know when those get delivered!

cj

 

[MikoKensington]

Well, I'm not sure. I never really got into the electronic movement. I do have some friends that were really in Juan Atkins and company. I'll find out.

 

[hodad]

Miko
We may have covered some of this ground before. There was a great discussion/dissection of a Flickinger mic pre--PRR may have it available online. If not, I think I've got the bulk of it saved as a Word file. If you want, PM me an email addy & I'll send the info.

Tom

Edit--I just looked at the closeups of the boards--different circuit. I'll still send you the info if you want a look.

 

[hodad]

Miko
We may have covered some of this ground before. There was a great discussion/dissection of a Flickinger mic pre--PRR may have it available online. If not, I think I've got the bulk of it saved as a Word file. If you want, PM me an email addy & I'll send the info.

Tom

 

[rafafredd]

Here is PRR dissection. Right from my RO archives.

I hope PRR will not take me to court just because I´ve posted his drawing :razz: :razz: :grin: :grin: :razz: :razz: just kidding.

And here is some text by the professor:

That's what I would do any time I was bringing up a new (or not well understood) board.

An amplifier has to have reasonable DC voltages before there is any hope of it passing happy audio.

Since it is not passing audio well, I would certainly look at the DC voltages.

The most basic one is: does the output sit about mid-way between the supply rails?

For single-supply amps like tubes, say with 0v and +250V, I would expect/hope to see 60 to 200V at the output plate (and I would be dubious about anything beyond 100-180V).

That's for resistor-coupled; for transformer amps the voltage will be the supply voltage and you should check current.

In this case, the main reason to bother with a bi-polar supply is so the output DC voltage can be close to Zero. Which is another way to say "midway between rails". Perfectly-Zero for some DC amps; in an older audio-only amp I'd allow a fraction of a volt.

In further study, this circuit with these values is designed for +/-24V. It will starve below +/-21V, will be too hot over +/-27V. At +/-24V the DC voltages will be roughly as shown:

At lower supply voltages, if R2 is changed to suit the supply, the 19V-20V voltages above will drop along with the suply rails.

> I will have to build another PSU

What do you have, +/-15V? Change R2 10K to 5.7K (or tack a 13K or 15K resistor across the 10K). That will set it up for +/-15V.

If you are handy with pots, you could put a 10K pot and a 10K fixed resistor in series, that 10K-20K combination across R2. If you do that, be very careful: at one extreme the output transistors will be over their power rating.

Get a battery-powered DC voltmeter across R11 (or really any of the 10 ohm resistors) and don't go over 0.25V across the 10 ohm resistor. 0.1V (10mA) is probably a minimum current. 0.15V may be a good safe value.

With an R2 that suits the supply, no audio, measuring at the DC output (this board has both DC and AC output pins), and something like a 10K resistor from the DC output to the feedback input (the bottomost finger in my mirrored image), then you should see nearly-Zero volts at the output. Probing at random, you will find the supply rails, some voltages a few-tenths below the supply rails, some pins around 2/3 of the positive supply.

The two 600O resistors are the input transistors' Base pins. Both of these should very-very close to Zero (probably within a milliVolt).

 

[rafafredd]

And here are more comments that I saved as a TXT file with some inputs by Dan Kennedy:

Thanks PRR.I will give the valuesaccording to the mirrored image and values you kindly posted)
R1:10ohm
R2:10k
R3:600ohm
R4:10ohm
R5:100ohm
R6:3k
R7:5k1
R8:3k
R9:3k
R10:3k
R11:10ohm
R12:10ohm


Opps! Sorry! I flipped it to make more sense to my eye when going from topside to copperside view.

R3 is 600 ohms? That seems very odd. Either this is a mix-amp or someone was wedded to 600O systems (which were already going out of fashion). I would arbitrarily replace R3 with 10KO for now.

My best guess is that it starts to work right at +/- 22.8 volts. +/-24V therefore seems reasonable, but the current in the output stage goes up very fast as the supply voltage goes up. (The downside of the simple resistor in the input emitters.)

It is still starved at +/-18V. Even though it may "work", it will have crossover distortion.

Consider replacing R1 and R4 with 100O resistors. It gives a little more supply decoupling, and "softens" the tendency to run-away if the supply voltage is over +/-24V.

If you have a +/-18V supply, start with that. With the external resistor connected, the output should sit very close to 0 volts. More than a tenth volt off of zero means it isn't working. If you can sweep the power slowly up to +/-24V, it may "snap" to zero volts around +/-22 or 23V. Or just try it on +/-24V, but keep a finger on it in case the output transistors (furthest from the connector) want to overheat.

PRR


I had a chance to look at the 101 amp.

It is similar in some respects to the Flickinger, but I'd say the Flick is quite a bit better.

They both use the (2nd) diff amp to do the phase splitting to drive the quasi-comp output stage, but instead of having differential drive to it, the SS drives just the base of one half, the other base tied off to a voltage reference.

The input stage is just one transistor instead of a diff pair, which puts the feedback at the emitter of the input transistor rather than into another high impedance node as provided by the (1st) diff pair in the Flickenger design.

It's a lot easier to see it and go "a ha" then it is to describe it though. I don't have a scanner...

Dan Kennedy

I hope it´s not a problem to post this info...

 

[rafafredd]

Well, I´ll be doing a backup of all my RO archives that´s on my HD now!

 

[hodad]

I just remembered I have pictures up still of the board from the first discussion. Look here:

http://www.wee-scottie.com/tcr/flickinger.html

Tom

 

[rafafredd]

Unfortunetly I didn´t saved the entire thread in this case, but this info should help you. If not, let PRR know it and I´m sure he will be here sometime.

 

[Mundox]

Hey Hodad, this card is different than the one we have. Did you get yours to work? I got mine working at +- 18V for some reason. They sound cool (well actually warm )

 

[hodad]

mundox--
Not there yet--I've been trying to figure out what I might pair it with so that I don't have to burn a whole power supply on one pre. What did you end up wiring in for input attenuation?

 

[hitchhiker]

Hi folks, total newbie here.

I was looking at those Flikingers and thought it looked like 8 transistors,

where as the circuit PRR worked out had 6.

Am I misstaken about the 8 ? I'll bet there gonna be a very good sounding circuit.

good one Miko.

Lance

 

[MikoKensington]

As I have told a couple, I'm willing to donate some of these to some Mad Scientists here at The Lab. I can't possibly use all these by myself. But I'd like to see what others can come up with for applications. And help me figure out what the hell I'm going to do with them. :grin:

PM me, if you think you're up to it. If they're good maybe we can have our first Project at our new home. Maybe?

 

[Winston OBoogie]

...

 

[SSLtech]

Winston O'Boogie can be reached at:

Pooh towers,
Land's end Street,
John O'Groats,
Beatleville.

I'd love a couple, but honesty gets the better of me and I have to confess that I could only hoard them for now... I have too much else to get on with at the moment.

..That said, this is a cracking deal for an inquisitive tech with some free-time! (a bit of an oxymoron I fear... it's the truly interested techs who seem to be the best... and as a result, they never have any free time. -Or any cheap time, for that matter! :wink: )

Keef.

 

[nwsoundman]

Miko,

I PM'd you but don't see my message in my sent box. Can you let me know if you don't get it?

NWSM

 

[Winston OBoogie]

...

 

[MikoKensington]

I realize how long it takes to work on something. It takes even longer to finish something. Shoot, I've had some Quad Eight cards on my bench for over a year now.

I'd still be willing to send a few out to the group. I will be selling them shortly after I get them in the hands of the brave few. So, if you are REALLY interested in helping, let me know. I understand it could take a while, and that's fine. My only request is that your findings get posted for everyone to see.

I'm going to make a list for SINGLES and DUALS. Get in touch and I'll put you on a list. After that, the rest will be for sale on THE BLACK MARKET.

Rock On Fellas!