Altec 902-8B/511B Reunited!!!

[Deang]

"...there were some discussions earlier today with Al, and he introudced some really high ohms values that are involved in the autoformer in the way the autformer does its buisness."

I thought I did a decent job of explaining how that worked in the other thread. http://forums.klipsch.com/forums/3/749510/ShowThread.aspx

If one doesn't understand how an autoformer works, or how to scale the values based on the reflected impedance from the various taps -- they should probably refrain from building networks until they do. Use the link I provided for the calculators in my post from the link above, get out some paper and pencil, and start playing with the numbers. It's just something you have to do -- or you'll never understand what you're doing or why you're doing it!

Because of some of things being inferred around here as of late, I'm running extremely low on patience and quickly losing my desire to participate on this forum. I'll be happy to teach what you need to know Charles, but you're going to have to pick up the phone and call me to get it. Posting anything that I believe to have value has become an exercise in futility.

[chops]

"...there were some discussions earlier today with Al, and he introudced some really high ohms values that are involved in the autoformer in the way the autformer does its buisness."

I thought I did a decent job of explaining how that worked in the other thread. http://forums.klipsch.com/forums/3/749510/ShowThread.aspx

Because of some of things being inferred around here as of late, I'm running extremely low on patience and quickly losing my desire to participate on this forum. I'll be happy to teach what you need to know Charles, but you're going to have to pick up the phone and call me to get it. Posting anything that I believe to have value has become an exercise in futility.

I don't know... I thought you did a pretty good job of explaining it. I think I have a pretty good idea on how it works now. But I believe your comment above was directed towards someone else and not me.

I first learned about step-up and step-down transformers through my father when he was rebuilding and customising the rectifier for the pipe organ. Hey, you have to convert some of that 220V A/C to 15V D/C somehow! [] See, the only thing in the pipe organ that uses 220V is the 3/4 horse blower and main breaker box. Everything else on the organ runs off of 15V D/C.

Then, when I won my very first auction on eBay over 8 years ago, I learned about output autoformers on my new (to me) McIntosh MC250 amp. Actually, I guess those on the Mac amps would be considered "constant impedance" transformers, since they make the amplifier see only one impedance, no matter if you connect a 4, 8, or 16 ohm loudspeaker to it.

Dean, if you could PM me your phone #, I might give you a jingle on Tuesday. Just let me know when would be a good time to call.

Thanks,

Charles

[djk]

Basic principle of autoformer with swamping resistor and tap switch, allows constant impedance and frequency with tap changes:

http://www.jblproservice.com/pdf/Network%20Schematics/3115%20Network.pdf

Basic principle of high frequency boost by bypassing autoformer attenuation at higher frequencies:

http://www.jblproservice.com/pdf/Network%20Schematics/3115A%20Network.pdf

[Guest " "]

"Basic principle of high frequency boost by bypassing autoformer attenuation at higher frequencies:

http://www.jblproservice.com/pdf/Network%20Schematics/3115A%20Network.pdf"

Thats a good validation from an independent source of what response 754041 was trying to explain.

Two ways to compensate for the diiferent effects introduced by the autoformer.

The by pass approach is intresting implementation of using a by pass capacitor...uses a user selectable feature with different cap loads......kinda implies you can select the frequency point you wish to by pass the autoformer.

Thanks for expanding on this

[Deang]

Nevermind.

[chops]

Nevermind.

??

BTW, you have mail! []

[Macho Nacho]

tasty

[chops]

tasty

I don't understand the "need" for people to post stupid crap that's totally unrelated to the subject at hand. [:@]

Dean, Al, someone...

What would happen if I took one of these 2uF motor run caps to bypass the autoformer and connected it straight to the 902 driver (6.4 ohms - 8 ohms) from the main input while the 902 is still getting its main signal through the autoformer?

Would this give me the already 800Hz crossover point attenuated -9dB via the autoformer PLUS a 10kHz - 12kHz unattenuated secondary crossover point to help the 902's output above 10kHz?

If so, which lead on the 902 would I connect the 2uF cap to, + or - due to the phase reversal of the cap?

Here's a small diagram I just drew up to help explain what I'm getting at...

[Guest " "]

tasty

I don't understand the "need" for people to post stupid crap that's totally unrelated to the subject at hand. [:@]

Dean, Al, someone...

What would happen if I took one of these 2uF motor run caps to bypass the autoformer and connected it straight to the 902 driver (6.4 ohms - 8 ohms) from the main input while the 902 is still getting its main signal through the autoformer?

Would this give me the already 800Hz crossover point attenuated -9dB via the autoformer PLUS a 10kHz - 12kHz unattenuated secondary crossover point to help the 902's output above 10kHz?

If so, which lead on the 902 would I connect the 2uF cap to, + or - due to the phase reversal of the cap?

Here's a small diagram I just drew up to help explain what I'm getting at...

that basiclly what the attached schematic shows when the selector is in the medium position. only difference is the addtions of r4, r2, and r3.

So yes, someone has been there, done it, and put it into production.

I am sure it has it's pro's and con's.

BypassAutoformerAtHf.pdf