Need Electronic help

reeltrouble1

Ok guys, I am stuck, over the past few days I have been building an AI-1 interconnect. The idea being to run two amps mono to the SDA-1C. I have been in touch with Ken at Polk on a daily basis for the past few days, he has been most helpful, but just cant get this cable to work, tried everything he has suggested and some other things so I am out of ideas, first thing some pics.

The first is of a modified AR sub cable I am using for the pin connector and the blade connector I fashioned from some speaker wire and a metal disconnect blade.

reeltrouble1

Close up of the terminal block, the black wires coming from the transformer hooked to positions 1&2 are the primary side, the red wires hooked to 3&4 are the secondary side. The left speaker pin wire is hooked to position 1 the blade to position 2.
The right speaker pin is hooked to position 3 and the blade to position 4.

reeltrouble1

A picture for reference showing the cables and project box, transformer and terminal connector.

reeltrouble1

OK, so the problem is that when I plug everything in the SDA drivers have no sound coming from them, a bad thing. During the testing phase I am using a single stereo amplifier with the negative speaker wire cables unhooked, positive cable is connected to the amplifier and each respective speaker, with this config only the SDA drivers are active. I am using the DSOTM disc as the stereo source from the cd player. If I use my standard polk interconnect the SDA drivers work fine, if I use the homemade cable without the transformer the SDA drivers work fine. Seems the speaker terminals are fine.

So to begin I cut the sub/pin cable in half I find two 20 guage wires one red, one white, the braiding and insulation, using a multitester I determine the red wire is connected to the cable pin, I cut the white wire short of the red, strip the insulation from the red wire and add the spade connector you see in position 1 on the terminal block. I take a piece of speaker wire strip both ends twist the wires together and add the blade connector for the speaker to one end and the spade connector you see in position two to the other. I connect the black wires coming from the transformer to their side of the terminal block in positions 1 and 2, the schematic diagram sent with the transformer identifies which wire coming from the transformer is #1 and #2. This completes the primary side connections.

I test for continuity at both the terminal block and the speaker end connectors I get a positive tone indicating continuity at all connections.

I repeat the above process for the secondary side, again I get a postive tone on the meter showing continuity is present.

With everything hooked up and plugged in however the SDA drivers remain silent.

I check for continuity at the terminal connector from the primary side to the secondary side with the amplifier off there is no continuity with the amplifier energized I get continuity from primary 1 and 2 to the secondary side both 3 and 4.
This would seem to be correct.

I try moving the wires both transformer and interconnect, move 4 to 3 and 3 to 4, no luck still no sound from SDA. I do the same with 1 & 2, again negative results.

My understanding of the isolation transformer is that its job is to allow the circuit created on the primary side to pass to the secondary side without making a mechanical connection, this is done through electro magnetism, this transformer is desgned to pass even voltage from primary to secondary, the schematic indicates an iron core with a electrostatic shield between the windings.

One last thing I tried, instead of using the blade into the speaker terminal slot I used alligator clips from the connector to the negative binding post, again negative result. The transformer is the Stancor model indicated by Ken as being the correct. He has examined the attached pictures we have spoke and really he is also puzzled as to why the SDA drivers do not function.

If I have not confused you totally, anybody, got a clue.

RT1

F1nut

If you have 1C's with right channel serial numbers 6001 through 6310 and 6501 through 6678, left channel serial numbers 5975 through 6370 and 6532 through 6656 the AI-1 will not work, although I can't remember why. Has Ken mentioned any of this?

reeltrouble1

Yes, Jesse, am aware my speakers are right 8149 and left 8215 so they will work, would of been to simple to just fit into the forbidden group. Although I am thinking I am just missing some little thing here, so thought maybe someone would see it, like the serial numbers, thanks though.

disneyjoe7

Could transformer phase have anything to due with this?

Is the plus connected to the dot side of transformer, so the plus of the other speaker is connected to the dot of the other side?

I guest you could switch one side wiring at the transformer to check. + to - swapped to each other.

Not sure so if this is completely off base sorry.

reeltrouble1

Yes, Steve, the pin connector is connected from the speaker to the primary side dot(position one on the termianl connector) I have tried switching the secondary to change the phasing but no difference, I am not getting weak or hollow sound from the SDA drivers I am getting no sound at all.

F1nut

Ted,

I pulled my AI-1 and it doesn't look like yours, so I'm not sure this will apply. I measured Ohms with a digital VOM and got OL on the spades with about 6.50 Ohms on the pins. What that means to you I'm not sure, but to me it means I need to dust behind the he-man rig a little more often. :eek:





FWIW, I do remember someone commenting that one of the transformers on the list didn't work for this purpose, wish I could remember which one.

F1nut

Been digging around and it looks like the transformer from Newark Electronics works just fine.


Here's a bit more.......This can be any specific cable you wish to customize as a pin/blade cable to your SDA's and with the A1-1
(isolation transformer). It would be from each side of the transformer. It will be cut into 2.

........order a isolation transformer from NEWARK ELECTRONICS

F1nut

More digging...

"Thanks for the information. Now if I could only figure out why the volume is only about 1/3 of what it should be :-(

My guess is that I probably need a better isolation transformer. One that is more like in the original A1 interconnect cable. If somebody had a part number it would be greatly appreciated. I have tried 2 of the 3 on the list that Ken gave me, but both seem to have alot of signal loss. Ken had made a suggestion about trying to use an isolation transformer more designed for audio, but I am at a loss as to what one or where to get it."


***
"Here are 3 transfomers to try,

SPC Technology # 81N5406

Stancor # 01F043

Magnetek Triad # 03F1017"

***
"You can order those isolation transformers listed here:

http://canada.newark.com/

or in the U.S.
http://www.newark.com/"

***
"Hi Guys,

I have already tried SPC technology and the Stancor one. The only one I have not tried is the Magnetek. Maybe if I twist my brothers arm real hard, I could get him to sell me my Adcom GFA-555II back. He does have a Adcom GFA-545II that I could probably get him to sell me for $150. That might be cheaper in the long run. The last isolation transformer I ordered from Newark cost me more for shipping then the isolation transformer :-(

These are the 3 options I have:

1. Buy a third isolation transformer and hope it works.
2. Run the SDA2B's in the rear without the interconnect cable.
3. Purchase the Adcom 545II for the rears and use the B&K amp for the center and evenutally for 7.1 when I upgrade.

Another question regarding amps. This may seem stupid, but what exactly is the difference between a common ground amp and a floating ground amp like the B&K ST1430."

***
"Check the output impedance of the amp. The sda effect will be diminished if it is too high. Most tube amps usually have this problem. What is too high you ask. Check with Ken. He helped me out a couple years ago when I tried to use an Audio Electronics Superamp."

disneyjoe7

Have to agree, it's a transformer problem.

I think you're using a step down transformer (120vac to say 12vac) not an isolation transformer (12vac in 12vac out). Just ratio's more then anything 10 to 1 vs 1 to 1.

hoosier21

Ted

It is a 1 to 1 transformer right? Which model do you have?

I remember somebody on here making one of these and saying something about polarity "swapping", either the transformer was marked wrong or they had to hook it up opposite from normal??

Hope I don't muddy the water with this great information.

reeltrouble1

I am using the Stancor Transformer, purchased from Newark, #01F043 is the Newark Stock number, it is definetly marked as an isolation transformer not at step down, the Stancor number is p-6411. Schematic indicates input 115v, output 115v or as Russ asked yes it is a 1 to 1 transformer. Willl output 0.13 amps

I tend to believe the problem is with this transformer, however, my question is this:

With the amplifier turned on if I touch the meter's lead to primary 1 (black wire 1st screw on the terminal) and the other lead to either red 3 or 4 I get continuity. If I turn the amplifier off, then the continuity is gone when I do the test, to me this indicates the transformer is working correctly, If I was at least getting some weak sound then I would think it would be the phasing coming from the secondary side, but I get nothing at all.

I do not notice any heat coming from this transformer does this sound correct?

madmax

You should not get any heat. You could unhook the xformer, measure the resistance between leads 1 and 2. Whatever the resistance is should be about the same as leads 3 and 4. I'll measure my xformer tonite and let you know what it should be.
madmax

madmax

Originally posted by reeltrouble1
During the testing phase I am using a single stereo amplifier with the negative speaker wire cables unhooked, positive cable is connected to the amplifier and each respective speaker, with this config only the SDA drivers are active.
RT1

THIS is probably your problem.


This works for sure when you use a straight sda cable but with an xformer in line I don't think it should. I believe this works with the standard cable because there is a solid connection between the two grounds (through the cable) but when you put the xformer in you break this ground connection. (Breaking this ground connection is the PURPOSE of the xformer). With the xformer in line there is no longer any connetion between the two sets of drivers. Try the system with the transformer with the two amplifier grounds connected. If it sounds funny try switching leads 1&2 or leads 3&4. As hoosier pointed out there is a need to change polarity there.

madmax

reeltrouble1

Ah Ha, yes Max now that you say it, it does make sense, BTW, I did check the reading on the primary and secondary leads before I started, the reading was like 52 ko or something like that, more over the readings were identical which is what you want correct?

Now Ken's written instructions were specific in testing the polarity with the ground wires removed from the amp, maybe this is why the other fellow F1 mentioned was having a time of it.

I will give the system a try with the amp ground connected.

RT1

DAGLJAM6

I believe that's shown in the hand drawing for the DYI setup at the Yahoo groups site.
If you check that site you'll see a relatively comprehensive overview of the engineering behind the connector.
If you need the site info or the JPegs I can email them when I get
home this afternoon.

Dave

reeltrouble1

Thanks Dave I would love to have a look at it, please send me the link when you can.

RT1

DAGLJAM6

Here ya go:
http://groups.yahoo.com/group/mikespolkpage2/
You'll have to set up with Yahoo but once in go to the "picture"
link on the left side and once in that screen check for "DIY A-1..."
The picture is best looked at printed due to size.
But I saw that one specifically states "reversing phase" on one side of the transformer. Other pics in that series show the specific
transformer/s you can use.

Dave

reeltrouble1

Thanks for the link Dave.

Well it seems Madmax was correct, the negative speaker wires need to be hooked to the amp in order for the ground to be established, at least when I did the SDA drivers did come on, although they do not play as loud at the same volume as the stock cable does.

So now what, be happy with it as is? The Yahoo site recommends the Newark p6412, Ken at Polk instructions says the p6411, the 6412 is a little bigger with more capacity, or maybe a step up style transformer?

At least it is working, Newark does correctly identify the polarity on the schematic they send with the xformer, it is pretty easy to hear the difference though when you switch the wires and listen.

Thanks for the help everyone. Y'all just a bunch of Ga. peaches!!

:cool:

RT1

hoosier21

Originally posted by reeltrouble1
or maybe a step up style transformer?

A huge no

reeltrouble1

Yea, Russ, after I wrote that about a step up xtansformer I later realized it would be a very bad idea and would fry things, I was really meaning to say someway to boost the signal without increasing the voltage to the secondary, the next model up will output .30 amps as opposed to the .13 that the one I am using does at 115V, think this will make a significant difference? It is over twice as many little electrons dancing down the pipe.

The thing is only like 22.00 bucks, but got to order it, in the mean time the mono set up really does add some significant power at over 400 wpc, will have to spend some time kicking back and listening, next step I make will be the tweeter change, with all the added power I think it would be a good move.

Not that the NAD 2700 had a problem driving the speaks in stereo mode, when I checked today it easlily pushed 105-110 db at 10:00 on the volume both channels driving, this is already getting insanely loud, however, it was easy to listen to.

RT1

disneyjoe7

Originally posted by reeltrouble1
easlily pushed 105-110 db at 10:00 on the volume both channels driving, this is already getting insanely loud, however, it was easy to listen to.

RT1

Heck, I do 105-110 db at 7:30am (in my undee's :cool: )

BTW, yes I think a bigger transformer would help. I glad you got that setup to work.

madmax

Originally posted by reeltrouble1
the next model up will output .30 amps as opposed to the .13 that the one I am using does at 115V, think this will make a significant difference? It is over twice as many little electrons dancing down the pipe. RT1

Think about it this way. The peak voltages on most amps is about 70 volts. Power is voltage times current. At the most the xformer you are using would be 0.13x70=9.1 watts. Not very gutsy but then again the SDA drivers are fairly quiet anyway. A problem with the smaller xformer is you might be saturating it. Don't know much about where that happens and what it would cause exactly.

madmax

BTW, I forgot to measure my xformer but it looks like you have a handle on it now.

dbnh

Originally posted by reeltrouble1
Yea, Russ, after I wrote that about a step up xtansformer I later realized it would be a very bad idea and would fry things, I was really meaning to say someway to boost the signal without increasing the voltage to the secondary, the next model up will output .30 amps as opposed to the .13 that the one I am using does at 115V, think this will make a significant difference? It is over twice as many little electrons dancing down the pipe.

The thing is only like 22.00 bucks, but got to order it, in the mean time the mono set up really does add some significant power at over 400 wpc, will have to spend some time kicking back and listening, next step I make will be the tweeter change, with all the added power I think it would be a good move.

Not that the NAD 2700 had a problem driving the speaks in stereo mode, when I checked today it easlily pushed 105-110 db at 10:00 on the volume both channels driving, this is already getting insanely loud, however, it was easy to listen to.

RT1

I'm surprised your tweeter protection didn't kick in, I know mine would at that level.

Tour2ma

One possible reason:
Lesser power ===> clipping ===> tweeter protection

One other:
The thermal protection Polyswitches have weakened with age and cut out earlier than they were meant to.

Side note: Quotes can be edited...

reeltrouble1

Over the weekend I changed the smaller p6411 xformer out for the Stancor model p6412, their was a big difference in the sound volume and SDA effect coming from the SDA drivers, I believe the smaller windings in the original transformer just had to much resistance along with its rated low output, if you are going to build a cable save yourself the trouble and just get the p6412 xformer to begin with.

I am now pumping over 400 wpc at high current to the 1C's I am hearing deeper bass extension along with more detail, this was a good jump for me. I had some resevations about the NAD in the bridged mode turning harsh but I do not find this to be the case, they still have that same warm, I guess "british" sound , similiar to my vox guitar amp.

Newarkinone electronics company treated me very well, when I told them the original xformer was not working out for me they credited my account the full price and did not require me to return it, something about it having a value of under 25.00. Just told me to keep it or throw it away.

RT1

F1nut

Excellent news Ted.

dbnh

Originally posted by Tour2ma
One other:
The thermal protection Polyswitches have weakened with age and cut out earlier than they were meant to.

I agree, I need to develop some soldering skills and put in another pair.

Originally posted by Tour2ma
Snide mote: Quotes can be edied...

Tour2ma

That's the spirit, dbnh....

One other thing...

Time was when my SRS's tweeters would go away due to the poly's doing their thing, but since I went bi-amp on my Sunfire, it has not happened. No even at volume levels higher and for longer periods than before.

And previous amp was no weakling... It was Carver M-1.5t that I never saw exhaust its headroom...

Glad to read of your success Ted... and of another company that treats its customers right.

EDIT: This is them... yes?
http://www.newark.com/