Strange AA crossover

[Deang]

I only build like that after I've been sober for a week. I'm careful not to let that happen.

[jimjimbo]

Nothing that can't be fixed with big dollar speaker cables.

[mark1101]

That is hilarious.  I guess some people still take LSD.

[babadono]

On 11/24/2018 at 4:44 AM, pzannucci said:

Am I seeing right?  Is there a wire also across the one cap (or I'm blind)?  How does that work?  Something special here!!  

Now we're ready to plug it in.

Didn't even notice that at first glance. And it looks like it has a smaller value "bypass" cap across it too..to make sure it is a short at super high frequencies

[jimjimbo]

And, I mean,  the nerve to mix 1% tolerance Dayton caps with 5% tolerance Dayton caps....

[Deang]

I think it's a Super AA.

 

It has the swamping resistor between taps 5 and 0. The two cans are probably from when he first decided to try something different. The can in the middle looks too big to be a 2uF, so I'm going to guess it's a 4uF. Looks like he might have started by converting them to Bob's A/4500, then wanted to try something else.

 

The big can is probably a 13uF, and I think that Dayton might be a 26uF. That's 39uF, which is the original value for that design. The smaller coil connected to the two point barrier strip running back to the autotransformer is probably soldered to tap 5 - should be .20mH. There is a small sticker face down on the board -- I wonder what it says.

 

The smaller Dayton's should be 2uF and 4uF, but it looks like he has them in the wrong order. The two caps in parallel look too big to be 1uF caps. At the end of that mess, you have a white wire, circling around the can that's in the middle of the board, and then connecting to that two point barrier strip. Another white wire on the other side of it goes to the variable l-pad. The black wire goes to common on the main barrier strip, and the red wire to tweeter positive. So there's his tweeter attenuation.

 

There is red wire coming from Tap 3 to another two point barrier strip at the front of the board. He must have a small jumper that he was using to connect it back to squawker positive. With the exception of the low pass coil, that completes the circuit for the Super AA.

 

Okay, this leaves us with the last white wire and the larger air core. The white wire runs from tap 4 to the barrier strip, and jumps to the resistor, and then to squawker positive on the barrier strip. I think he may have been trying to get an in between setting, because with the somewhat fixed design with the T2A, all you get is -3dB and -6dB.

 

It looks like the stock low pass coil is wired in, which means the larger air core is not - provided that it's a 2.5mH. If he compared, I'm sure he would have found the stock coil to sound better. The DCR of that air core is much too high for that position.

 

Oh yeah, the can in the middle. It's just there in case he decided to go back to the other design. Cute little bypass cap. 

 

That's my best guess, which means I'm probably waaaaay off.

 

[Dave A]

3 hours ago, jimjimbo said:

Nothing that can't be fixed with big dollar speaker cables.

Oh man I goofed up when I took those off???

 

2 hours ago, jimjimbo said:

And, I mean,  the nerve to mix 1% tolerance Dayton caps with 5% tolerance Dayton caps....

And the cute little .1uf box things on the motor caps. Don't forget those now.

2 hours ago, mark1101 said:

That is hilarious.  I guess some people still take LSD.

Or never recovered from it.

 

32 minutes ago, Deang said:

That's my best guess, which means I'm probably waaaaay off.

And that is why you need this in hand to delve into. Admit it you are hooked.

[Deang]

Pretty much figured it out without having to wear a hazmat suit. I’m good. 

[ClaudeJ1]

On 11/24/2018 at 7:50 PM, Dave A said:

 

Say I have two. One for each of you guys. I can wait for the schematics.

Ship it and I'll draw it up, no problem. I can even simulate a curve of it on Klipsch drivers.