Need help w/ SDA A1-I Interface Cable

Kenf616

Specifically, I need to either locate one (buy it from someone), or learn how to make one. I did contact Polk, and someone was going to email me the list of materials required in .pdf format. But, that was last Thursday.....so I am beginning to wonder if that is going to happen.

Does anyone have this list of materials required, or know how to make this cable? This this needed for a pair of 1.2TLs. I have the regular pin/blade SDA cable.....but need the one with the Isolation Transformer on it.

This cable is for Non-Common Ground Amplifiers...which many of you already know.

Thank you for what ever help you can provide....

Ken

pjdami

Is this what you are looking for? Courtesy of polksda:

http://polksda.com/A1_Interconnect.pdf

pjdami

Oh yeah. Welcome to Club Polk and happy listening!:)

Kenf616

Thanks for the reply pjdami......when I clicked on the link you provided, it gave me an error message, and said I don't have permission to access the A1 Interconnect.pdf on this server...

?????

pjdami

try this:

http://polksda.com/

And click on "what would you like to see"

Kenf616

Okay, I was able to pull it up from that.....I'll have to study this for a bit.....I have the SDA cable, but I'm not sure I know enough about the things involved to tackle this....I sure don't want to ruin a perfectly good SDA cable. How many members out there have succeeded in doing this??

Thanks pjdami for the start....I appreciate it!

pjdami

You are welcome. I do own some SDA's but use a common ground amp so I have not performed that procedure.

You can make your own SDA cable too from oxygen free speaker wire. It's nothing special as I have read on the forum here that the frequency range is limited on the signal it has to carry.

Try a search for "sda and cable" and you will get a lot of interesting reading material and some tips for sure.

Hopefully, someone who has performed the above procedure can help.

Paul

F1nut

Here's a slew of AI-1 info for you to sort though.

http://clubpolk.polkaudio.com/forum/search.php?s=&action=showresults&searchid=280612&sortby=lastpost&sortorder=descending

Kenf616

Jesse,

Thanks for the link....Yes, I have been digging through those threads, and wonder if I can "get by" with "strapping the grounds or negative terminals together" as DK suggested. But, I have no idea how I do this....through the speaker terminals? or using the ground screw on the back middle of each amp. I'm hoping I would be able to use the "ground twist screw" on the back of each amp, and just connect them together....using the same type of cable, I am using for the speakers. The amps in question are Carver M500t (2) with the SRS 1.2TL.

Do you know the correct way to do this with the Carvers?

Ken

F1nut

Ken,

I don't know if the Carver's can be connected that way. Some amps can, some can't, so it's important to find out before trying it. If they can then either connecting the negative speaker terminals or the ground screws would work. In the end I think building the AI-1 is the best way to go.

The thread Reeltrouble did spells things out pretty well. I'd follow his suggestions and if you have any questions just ask him. He's a great guy and more than willing to help.

Kenf616

Thank you again, Jesse.......Yes, I saw that thread and discussion from Reeltrouble's post. A lot of good information there especially regarding chosing the right transformer for the best output. I just need to try and get all the facts regarding this cable and the amps - inverting/non-inverting design, etc. before I decide to cut a perfectly good SDA cable in half!! I am not adept with a soldering iron, actually I don't own one yet....I wanted to see if modifying this cable is something I could handle...

Ken

hoosier21

Originally posted by Kenf616
before I decide to cut a perfectly good SDA cable in half!! Ken

Agree 100%, if you are going to make an AI-1, save the original interconnect, and make a completely new one with the transformer in place.

Tour2ma

I do not believe that you can connect two bridged, Carver M-500t's as you are suggesting, but you can call customer service at Sunfire and ask. Sunfire is the place to go with questions on old Carvers.

Kenf616

Tour2ma,

Thanks for the info on Sunfire. As far as the connection of the 2 amps, I wasn't planning on bridging them I didn't think, just biamping ...horizontally? (someone described as such). Just to be clear......I want to use (1) M500t for the low freqs, and (1) M500t for the high frequencies. That is my intention, whatever it is termed.....I thought someone once said that was Horizontal Biamping, if I'm not mistaken.

Maybe someone can verify that for me?

Thanks.

P.S. I did get an email from Ken Swauger earlier this afternoon, that I am currently going over.....if you like I can post his reply here, and we can go over it.

Ken

F1nut

Ken,

You don't need a AI-1 for what you want to do. Both of your amps are common ground amps and when used in a bi-amp arrangement they will remain common ground amps.

Kenf616

Jesse,

I went with the strong possibility the M500t was a non-common ground amp based on (1) a Polk CS person who thought it was - he owned one long ago, and (2) From all of the past discussions with the 1.0t and 1.5t of the same era - damage being inflicted on one, I erred on the side of caution. I am still not sure about that, but from dissecting Ken's email and instructions just now.....and making the connections successfully, you are correct in that I now know I do not need the AI-1 cable for biamping the 2 amps. But, I don't think I ever would have figured out how to do it myself.....it is a really funky way straight from Carver's manual. I'm just glad I regurgitated the important parts in my email to Ken, to give him enough information to help solve this for me. Ken certainly saved me a lot of time and future frustration in trying to get this solved. He is the man !!

I want to ask a follow-up question or two, based on what I have learned so far from everyone here....

Let's assume I go with (2) M500t amps driving the 1.2TLs. One amp driving the highs, while the other drives the low freqs.

First, will this favorably impact sound quality vs. just using one amp to drive both speakers? Second, what is the BEST way to hook up these 2 amps to the 1.2TLs. FYI....each one is rated for 251 watts RMS into 8 ohms.

Thank you for your additional thoughts...

F1nut

Originally posted by Kenf616
Let's assume I go with (2) M500t amps driving the 1.2TLs. One amp driving the highs, while the other drives the low freqs.

First, will this favorably impact sound quality vs. just using one amp to drive both speakers? Second, what is the BEST way to hook up these 2 amps to the 1.2TLs. FYI....each one is rated for 251 watts RMS into 8 ohms.

1. I think only you can be the judge of that.
2. I'm not clear on what you're asking.

Kenf616

Jesse,

For the first question, it sounds like this will be a subjected answer based on any perceived benefits which may vary from person to person.

In the second question, I was referring to getting the most out these two amps, and the connecting options that I have....

1.) (Using just (1) M500t for the pair of 1.2TLs = 251 wpc, or...

2.) Biamping with (2) M500t - 1 for highs, 1 for lows, or.....

3.) IF it is POSSIBLE (50/50 chance?) of doing the monoblock thing using the AI-1 to achieve 500 watts into a single speaker. Which even if I had an AI-1 cable ready to go, I wouldn't know how to make the connections.


Assuming these 3 options are possible, WHICH one should I end up going with to reap the best possible sonic benefits/sound quality?


Ken

Tour2ma

Not bridging... got it...

I bought a M-500t new back in the 80's and returned it as I was told it was not a common ground design (and knew there were SDA's in my future). I ended up with a M-1.5t.... and a used pair of SRS's.

The info I have is that the 1.5t is a common ground amp, and a VOM check of one of mine shows 0 Ohms between negative outputs posts.

I do have a 500t as well and its neg to neg resistance is about 6 ohms... same as the positive to postive reading... i.e., non-common ground.

So in any case with the 500t's you are in AI-1 land...

To maximize the utilization of the 500t's, with their ability to share a pooled power reserve between the channels, I'd think:
- vertically bi-amping would be the way to go vs. horizontal; and
- bridging would be competitive with vertical bi-amping...

Since the AI-1 is required, all options are available for you to check out.

And you can throw in a mono vs. bi-wire test when bridged just for grins...

Have fun...

Kenf616

Tour2ma,

Great post, thank you for the details on the non-common ground issue.

How does vertical biamping work with these? I am interested in doing this if it provides further benefits from available power. Isn't vertical biamping when you connect (1) M500t to each speaker? Would I need the AI-1 cable to biamp vertically?

Since I've just tried Horizontal biamping following Ken's email, I should be able to vertical biamp without the need for the AI-1 .....correct??

Can't wait to hear more.....thankyou!

reeltrouble1

Interesting thread to say the least. I certainly would not cut the existing connect to build the AI-1, however, seeing how you like to move amps around into different configs I would build one so you have it to use, there are just so many combinations of amping, one mistake and your fried.

RT1

Tour2ma

Are you saying you are now horizontally bi-amping without the AI-1? Only using the standard SDA interconnect?

Kenf616

Reeltrouble,

I agree with you on building the AI-1 from scratch completely if I decide to go that route. Believe me, it is NOT my intention to change amp configurations at all. I'm trying to determine what are my best options sonically. The 1.2TLs have only just recently been completed......all new drivers, side panels, grills,etc...these were the ones trashed in the pictures posted a few weeks ago. I also have perfect 1.2s....from before....sorry its a loooong story...

Anyway, I'll be using the 1.2TLs for front mains and 1.2s for the rears....etc, etc.

Kenf616

Tour2ma,

Yes, as of last night, based on Ken's suggestions in an email I received yesterday......

Here is what he wrote.....

"Let's see if we can figure this out. Since you are allowing each amplifier to remain "stereo" I don't believe you will need the SDA1A cable.

However you will have to follow Carver's instructions for common ground connections. The negative terminal, on the Carver, that will be used for both the left and right channels is the one labeled "chassis". Also the left positive and negative need to be reversed for correct polarity.

So, the left speaker's red terminal gets connected to the Carver's black terminal marked "chassis", the left speaker's black terminal gets connected to one of the "outside terminals" on the Carver.

The right speaker's black terminal gets connected to the Carver black terminal marked "chassis". The remaining right speaker's red terminal gets connected to the other "outside terminal".

You would do the same thing with the second amplifier and it's upper speaker connections.

Carver is indicating that the left speaker needs to be wired opposite in polarity to the right speaker and that both of the negative terminals, on the speakers, get connected to the "chassis" terminal. Then the two "outside terminals" one red and one black, become the positive connections."

I did this late last night and only "tested" it to make sure everything at least worked. I still need to listen critically to it....but, it was so late when I finished.....

Ken

reeltrouble1

Originally posted by Kenf616
Anyway, I'll be using the 1.2TLs for front mains and 1.2s for the rears....etc, etc.

Holy Crap SRS as rears and 1.2's no less........talk about getting your SDA groove on, ok so back to the thread, where are you at now, I have read so much I am bug-eyed!!!

Kenf616

Reeltrouble,

LOL, yes, tell me about it!! Now you get the picture of what I have been going through flipping through tons and tons of old extremely technical (and awesome!) posts here. Everything from Bi-amping/Biwiring/SDA's/Monoblocks/AI-1 - including your great post on the subject!!....to Raife's doctoral thesis on the subj of SDAs....lol..incredible Raife!! Actually, everytime I think I am getting it down Raife throws me another curve from an excellent old post!! In fact, just read his post on Biamping the Adcoms....and, I am afraid that I may have found the same results he encountered....which I am bummed by.

I am just starting to listen carefully to the 2 M500ts biamped horizontally. That is one amp driving the high freqs, and one driving the lows. Just keep in mind, the drivers aren't completely broken in about 5 days or so.....all 16 drivers were new....I could only salvage 1 SL3000, so I "borrowed" them from 3.1tls, 15tls, and bought 4 from dorokusai. So, only the PRs were the same. This connection is based on what the Carver manual says, and what Ken retranslated to me!...lol

Anyway, I listened for quite a while yesterday to just the (1) M500t driving both left and right in stereo with the SDA cable in place, and it sounded really terrific....nice almost 3 dimensional soundstage with Holly Cole's "I've Just Seen a Face - Dark Dear Heart" just pounding me in the chest, and her voice soft and sultry as ever.

Likewise, Ann and Nancy Wilson (Back to Avalon - Desire Walks On - one of my favs by Heart !) were seducing me as usual...they were simply incredible!!

But, that was then...<sigh>...with one ampin stereo.....I'm afraid now after just reading Raife's post, and giving the Horizontal Biamp set up a first critical listen......I'm beginning to think the bass soundstage has narrowed and become thin....some parts sound 3 dimensional....but not like before....and Ann and Nancy arent whispering in my ear.....and Holly Cole doesnt like me anymore.....hmmmm..

I need to go back and relisten...

Kenf616

Something else I noticed while listening to the Horizontal Biamp connection.....possibly confirming my suspicion on the thinner and thicker(muddy) bass response....the drivers both SDA and Stereo were NOT "flexing" as much at the same volume level. This was apparent to me, because yesterday the drivers (SDA and Stereo) were clearly more "active" the bass was tight, defined, and quite literally pounding me.

True, I am not sure how close the actual output was between Stereo or Horizontal Biamp at the given level ..... the Sony EP9ES processor volume read -30.0 db which is about 11 o'clock on the dial. It starts at -100.0 db, I think. 0 equals -100.0 db. I'm not sure I now how to measure that. I do have a Radio Shack SPL meter, but I'm not sure that would help here.

Tour2ma

Ken,
What you are hearing sounds suspiciously like what another SDA owner reported as his non-common ground amp was sinking...

EDIT: Thought I had a 500 manual 'round here... I'm looking for it...

EDIT 2: Hope I'm ringing false alarm here.. just reread your post about the diminishing SDA being a product of the swap from one 500t to two in bi-amp mode...

Kenf616

Tour2ma,

What?? Are you sure? The amps are not even warm...there's no smell of any kind....etc.

I was thinking its what Raife may have run into when experimenting/testing different Adcom set ups. Its more of a sound difference effect. The output has not showed any signs of dropping off at all....

Tour2ma

Nope, not sure.. thus the edits...

Still researching...

Kenf616

I have a manual of course....FYI Do you need me to look something up??