SDA-1B Think I found the problem!

wingzam

I started with a Soundcraftsman RA-7501,moved up to a Kenwood M2 and now am running a GFA-5800.From the day I got them the 1B's were going into protection mode what I thought was too early.I thought this was because the 1st two amps were clipping,but the GFA,which should have plenty of power,caused an early shut down also...
So i'm wringing my hands and beating my head against the wall..multi-tasking as I search the forums,when I find DarqueKnights 10-28-2008 thread on Nasty Polyswitches and lo and behold a ray of Darqueness shines into the former darkness!
I'm going to clip those little boogers outta there and see what happens...i'll probably blow some tweeters but what the hell,it will give me a reason to buy some 194's!
Any precautions or advice before I proceed?

Polkersince85

Either call Polk CS and get new ones or watch your volume.

Be sure the interconnect cable is connected.
.
.
.

wingzam

"My name is John and i'm a power Junkie"....I can't STOP!!!!
If anything i'll find out where the limit is!Actually,in that same thread one of the techs commented that the distortion level will give a good indication of when one approaches "Too Much" so I *think* I can work with that.

hearingimpared

wingzam wrote: »

"My name is John and i'm a power Junkie"....I can't STOP!!!!
If anything i'll find out where the limit is!Actually,in that same thread one of the techs commented that the distortion level will give a good indication of when one approaches "Too Much" so I *think* I can work with that.

I don't know if the Adcom is a common ground amp. If not you can damage both your speakers and/or your amp if its not. To check, take a VOM, with the power off the amp and speaker cables disconnected, check the resistance between the negative binding posts on the amp. It should read ZERO or near ZERO to be common ground.

Polkersince85

You will probably get what you deserve. Good luck.

hearingimpared

Polkersince85 wrote: »

You will probably get what you deserve. Good luck.

That's funny!

bigaltx24

If you're going to pull the HF crossover you might as well recap it while you have it out. I did mine a couple of weeks back, big improvement in sound quality. I used Dayton 1% films on the HF and Solens on the LF with Mills 12 watt resistors on both. I replaced the polyswitches with a .5 ohm Mills resistors. I've taken mine to some very high volume levels without the polyswitches and haven't hurt a tweeter yet.

george daniel

Careful with that volume control,,Eugene.

wingzam

bigaltx24 wrote: »

If you're going to pull the HF crossover you might as well recap it while you have it out. I did mine a couple of weeks back, big improvement in sound quality. I used Dayton 1% films on the HF and Solens on the LF with Mills 12 watt resistors on both. I replaced the polyswitches with a .5 ohm Mills resistors. I've taken mine to some very high volume levels without the polyswitches and haven't hurt a tweeter yet.

What is that .5 ohms resistor doing for the circuit?

And thanks to you guys for the feedback!

heiney9

The 5800 is NOT common ground, IIRC and depending on which Kenwood M2 you're running (the models with the Sigma Drive) might not be common ground either. Sigma Drive models have an extra set of speaker cables that are just hooked to either the pos or neg of each speaker, IIRC.

See link

http://www.drmaudioht.com/Kenwood_SigmaDrive.htm

H9

wingzam

"The 5800 is NOT common ground, IIRC and depending on which Kenwood M2 you're running (the models with the Sigma Drive) might not be common ground either. Sigma Drive models have an extra set of speaker cables that are just hooked to either the pos or neg of each speaker, IIRC."

Yes,that's the way I had the M2 with SigmaDrive hooked up.Glad you gave me the heads up on the 5800,whew!The fix for that is to tie the negative terminals together,right?

heiney9

wingzam wrote: »

"The 5800 is NOT common ground, IIRC and depending on which Kenwood M2 you're running (the models with the Sigma Drive) might not be common ground either. Sigma Drive models have an extra set of speaker cables that are just hooked to either the pos or neg of each speaker, IIRC."

Yes,that's the way I had the M2 with SigmaDrive hooked up.Glad you gave me the heads up on the 5800,whew!

Be sure to confirm my memory by measuring between the negative speaker terminals. I am going on memory, but I'm pretty sure the 5800 is not common ground.

wingzam

Yes,*hearingimpaired* addressed that procedure in his post above.If it's not common ground I should tie the negative terminals together then?

wingzam

bigaltx24 wrote: »

If you're going to pull the HF crossover you might as well recap it while you have it out. I did mine a couple of weeks back, big improvement in sound quality. I used Dayton 1% films on the HF and Solens on the LF with Mills 12 watt resistors on both. I replaced the polyswitches with a .5 ohm Mills resistors. I've taken mine to some very high volume levels without the polyswitches and haven't hurt a tweeter yet.

When I get into this thing i'll see what I dare do.I'd like to rebuild the whole thing but am kinda licking my wounds after buying the Adcom.Was going to sell my Pioneer SA-9500II and the M2 to pay for it...but,man it's hard to let go of those units now and I know i'd be sorry later!

heiney9

wingzam wrote: »

Yes,*hearingimpaired* addressed that procedure in his post above.If it's not common ground I should tie the negative terminals together then?

Yes, but measure first was what I was saying.

wingzam wrote: »

When I get into this thing i'll see what I dare do.I'd like to rebuild the whole thing but am kinda licking my wounds after buying the Adcom.Was going to sell my Pioneer SA-9500II and the M2 to pay for it...but,man it's hard to let go of those units now and I know i'd be sorry later!

Now that you have the Adcom you won't miss the Kenwood at all.........at all . I owned all the Kenwood Basic line in the mid 80's and I don;t miss it even a little bit.

H9

wingzam

"Now that you have the Adcom you won't miss the Kenwood at all.........at all . I owned all the Kenwood Basic line in the mid 80's and I don;t miss it even a little bit."

I was surprized to find it was a real toss-up between the two in this system.As I read in a few places on Audio Review the Adcom is "forward" with it's high frequencies,and a bit harsh.The bass is tighter but is lacking in depth.Understand that i've got it hooked up to a Sony HT STR DA90ESG and with the sound field set to just straight "Music" I can't change the bass or treble settings which is just outrageous with a unit of this price and flexibility!So I need to hook up the Pioneer to get adjustments back AND the Adcom may work better thru it otherwise.I look forward to that test!

heiney9

How it even functions properly with it being non-common ground w/the SDA's is beyond me. Also Audio Review is a horrible site to read reviews. The 5800 was the flagship before the 5802 and it's a Mosfet based amp and is anything but forward or lacking in bass depth. Your pre is definitely your weak link as well as the amp being run with SDA's while not being common ground. And with the issues you are having with the SDA's I wonder how you can even get a decent baseline for comparison

But, it's your rig and your gear.............go with whatever sounds best to you in the end.

H9

wingzam

Well,obviously I CAN'T get a decent baseline for comparison!That sir,is why i'm here!!And you sure know how to taunt a fellow Polkster - telling me that Audio Review is horrible and then NOT telling me where a good review site is!Do you enjoy feeding a hungry dog with an empty bowl??You are a twisted man H9 - I like that about you!:D

Schurkey

wingzam wrote: »

I'm going to clip those little boogers outta there and see what happens...i'll probably blow some tweeters but what the hell,it will give me a reason to buy some 194's!
Any precautions or advice before I proceed?

DON'T buy the 194s. Buy the SL3000/RDO 198s, and change the 4.4 uf capacitor on each high frequency circuit board to a 5.8 uf capacitor. Proven workable on the 1B, but not the 1C. (Thanks, inspiredsports!)

http://www.polkaudio.com/forums/showthread.php?t=74946

http://www.polkaudio.com/forums/showthread.php?t=91991

If your amps are not common ground, expect problems from the speakers, from the amps, or both. At minimum, expect really **** sound quality. Trust me, I know what a mere 20 ohms resistance on the ground between the channels sounds like; and it is VERY hateful on the 1B if not ALL the SDA speakers.

wingzam

Schurkey i'll keep that info in my folder.I'm excited to get these initial bugs corrected and see what i've got.I actually don't listen to *alot* of music so this set up has very little time on it,which may have saved it from damage,although I noticed the fans come on pretty quickly and they sound alittle rough,as if the bearings are worn,but this 5800 is in pristine condition and had a relatively small amount of dust inside.One thing though is when I blew the dust out I was blowing air in the wrong direction thru the fan tunnels and may have blown dust into the bearings..crap,there's always something!

heiney9

If the 5800 has one Achilles heal, its the auto fans. As they age they tend to fail either by not sensing temp soon enough or completely not working at all. Not every unit has this happen but it is kind of common.

H9

wingzam

With the fans coming on early lets hope it's just a matter of the aforementioned issues I need to straighten out,but thanks for the heads up on a possible issue.I should have done my check out,shakedown and clean-up alittle differently,but my time window was narrow and I have all this stuff to jockey around just to get the 5800 in it's place..too much stuff in a small place as a result of having to downsize!A rack with wheels will really help facilitate this hobby!

wingzam

hearingimpared wrote: »

I don't know if the Adcom is a common ground amp. If not you can damage both your speakers and/or your amp if its not. To check, take a VOM, with the power off the amp and speaker cables disconnected, check the resistance between the negative binding posts on the amp. It should read ZERO or near ZERO to be common ground.

OK on the 5800 there are 4 sets of speaker terminals:2 are labeled "Normal" and 2 are labaled "Bi-wire".
With the ohm scale set to 200 my readings across the neg. terminals (measuring in every variation of the 4 terminals) is 00.2 .With the scale set to 2K the reading is .000 .Do these readings show a Common Ground?

hearingimpared

wingzam wrote: »

OK on the 5800 there are 4 sets of speaker terminals:2 are labeled "Normal" and 2 are labaled "Bi-wire".
With the ohm scale set to 200 my readings across the neg. terminals (measuring in every variation of the 4 terminals) is 00.2 .With the scale set to 2K the reading is .000 .Do these readings show a Common Ground?

Yes indeed!

wingzam

OK thats out of the way,now it's on to the speakers!

Schurkey

wingzam wrote: »

With the ohm scale set to 200 my readings across the neg. terminals (measuring in every variation of the 4 terminals) is 00.2

I think you're all set in terms of "common-groundedness".

wingzam

Ok here's the crossover,i'm pointing at what I think is the polyswitch - I am right?

wingzam

Well,this is the first time i've posted a picture to this site and it doesn't enlarge so you can see anything.This is a round blue component at the very bottom of the lower crossover.The P/N is D-0905570,but the P/N on the schematic is RDE090A.


I'll start a new thread on this.

wingzam

bigaltx24 wrote: »

If you're going to pull the HF crossover you might as well recap it while you have it out. I did mine a couple of weeks back, big improvement in sound quality. I used Dayton 1% films on the HF and Solens on the LF with Mills 12 watt resistors on both. I replaced the polyswitches with a .5 ohm Mills resistors. I've taken mine to some very high volume levels without the polyswitches and haven't hurt a tweeter yet.

Big Al where did you get that resistor?

Schurkey

Judging by the location on the circuit board, YES that's the polyswitch.

When rebuilding the crossover, you could install a fresh and close-tolerance 2 ohm resistor in the same location as the existing 2-ohm resistor, and then install a second .5 ohm resistor where the polyswitch was. You could install a 2.5 ohm resistor where the 2-ohm used to be, (being careful to bridge the gap on the circuit board created by removing the polyswitch) and forget the separate .5 ohm.

You could simply delete that .5 ohm resistance entirely and have the treble increase in volume slightly. (my choice!) I suppose that would make the tweeters somewhat more susceptible to over-cooking at high volume or with an amp that clips. If you aren't going to run the speakers VERY loud or with the preamp/equalizer treble control cranked way up--it should never be a problem.

Schurkey

And by the way--if you happen to take a DC resistance measurement of the MW6509 drivers, I'd love to know the results. One of mine was 8 ohms; another was 9.5 ohms, and all the others were in-between but tended to be either below 8.5 or above 9.0.