1.2tl sda diy interconnect question

[Reagan]

I am interested in upgrading the interconnect using cores from Belden 89248 cable. Probably three twisted pairs woven together for a total of 6 cores. The factory setup has a pin connection and a blade connection. The blade is jumped to the black binding post (see photo). If I install a separate binding post for the new DIY interconnect, would I still need to worry about the blade connection? If the blade is only for structural integrity, then why is it connected to the black binding post? Sorry for my newbieness.

[Ricardo]

If you are using a common ground amp (which you should), you don't need the blade connector. Not sure about the A1 interconnect for non common ground amps, but I suspect in that case the blade does have a function.

Many of us here have changed the interconnect and use only the pin.

[Reagan]

Thanks. I'm anxious to see improvements (although it's hard to imagine any).

BTW, if I use a total of 6 - 18 gauge conductors, what would the equivalent wire gauge be? Any capacitance issues? My amp is a B&K Reference 200.2.

[Auraka]

WBT SLEEVE SIZE SELECTOR will calculate combined awg.

[riglehart]

I just built an AI-1 so am pretty familiar with this. Hope I'm not "talking down" to you, but this was all news to me when I started this.

If you have a common ground amp, the blade connection is redundant with the "common ground" in the amp. Common Ground means that the negative terminals of the amp are actually connected with a short. You can actually connect them with a wire and you have changed nothing, since they already are connected inside. So, think about it. The blade connector goes to one negative terminal of your amp, from there it is directly connected to the other negative. This negative goes to the other speaker, which also connects to the blade. This blade then goes across to the other speaker through the SDA cable and you are back where you started. A big circle with everything connected. So you don't need it.

HOWEVER, if your amp is not common ground, putting the straight cable on effectively hooks the two ground connections on your seperate amp channels together, which is bad on a non-common ground amp. The AI-1 is just a cable with a 1-1 transformer in it that is energized from pin-blade on each side which induces a signal without actually connecting both sides.

With my DIY AI-1, I didn't use the blade (until f1nut fixed it when he had it. Thanks BTW.). I would just put that cable on the speaker ground nut, since they are the same thing.

[F1nut]

Ah, so that's what you were doing. I thought maybe you were just sticking the twisted wire ends into the slot, so I added the blades. Thanks again for the loan, it was fun.

[Reagan]

Thank you for the help with my SDA 1.2TL/Interconnect questions. From what I have read thus far, the pin/blade connector on the interconnect cable only conducts current through the pins. Two internal conductors are connected to each pin. I have a couple of questions.

Q1: If the blade is only used for support, then why is the female blade connecter in the speaker hooked up to the ground speaker terminal?

Q2: Why are there two separate conductors connected to the same pins? Is this simply to increase the effective wire guage? Are they a twisted pair for RFI reasons?

Q3: I am considering making the interconnect using 3 twisted pairs of 18 AWG teflon insulated (Belden) cable cores (6 cores). This would result in an effective wire guage of 11 AWG. Does this sound like a viable upgrade option?

Thanks for any insight.

[Ricardo]

There is one conductor connected to the pin and one to the blade; the blade connects negative posts; if you use a common ground amp, the blade is not required.
Not sure where the idea of the blade being "support" came from.

WRONG!!!! Confirmed that the pin/blade connector only has wires connected to the pin :o

[strider]

The connection between the negative binding post and the blade is used when an AI-1 interconnect is hooked up. I needed to add this connection when using the AI-1 with my 2B's which, as far as I know, are the only model that is missing this. There is a signal through the blade portion of that interconnect. Far as I know, you are correct that the blade in the regular pin/blade cable is just to add isupport to the connection.

[Reagan]

http://polksda.com/A1_Interconnect.pdf

[Ricardo]

I read those instructions and saw where it says that both wires are connected to the pin....what can I say...I know nothing
(Though I am so tempted to take mine apart just to confirm that ;))

[Reagan]

I broke down and put a multimeter across the blades...no current. I was dismayed by noting the resistance across the pins was about the same as my DIY cable. I'm not sure if I'll be able to improve the performance with my design. Maybe I should go with the monster cable instead. What have others used with success?