New member with Polk sda srs2.3tl speakers, good story and questions....

vintagchris

Hi folks, new member here with some questions on my latest acquisition, a pair of Polk srs2.3tl, These speakers sorta found me, I was answering an add for a pair of adcom amps, at one point while i was asking him about the amps, I asked him what speakers he had run the amps on, he said he had run them on a large pair of Polks but had blown some of the drivers in the speakers, and basically quit using the amps and speakers some years back, we settled on a price on the amps and set up a time to meet.

When I got to his place he met me out front of his home and had me fallow him around to the outside entrance to his basement, I expected him to have them hooked to something for me to audition them, but he just had them setting on his work bench covered in years of dust he had not even taken the time to wipe off, this type of thing still amazes me especially with what he was expecting to get out of them, I told him there was no way I was buying the amps without making sure they worked properly, he replied ok grab one of the amps and fallow me.

We walked out of the basement and around to the front door of his home and walked into the living room, it was not hard to miss the two elephants in the room, I then remembered our earlier conversation and him mentioning the large Polks he used the amps on, and hear they were! he told me he had not used them in some time and that although they had some bad drivers they should work well enough to be able to let me know if the amps worked ok, I hooked one amp up at a time to make sure they worked properly, but as I was testing them and listening to them I was thinking to myself, damn these speakers sound good, and deserve to be repaired and brought back to useable condition so someone could enjoy them, and that someone was me!!!

I asked him if by chance he was interested in selling the speakers as well, he told me make an offer, we haggled back and forth a bit and after some negotiation he reluctantly agreed to part with them and we shook hands, only to have his wife say you sure you want to sell those! he then started back peddling and said he couldn't sell them! I was disappointed to say the least, we had shook hands! but i understood, I was there for the amps not the speakers which he obviously hadn't thought of selling, so i told him not a problem that I understood, paid for the amps and said I was going to carry them out to the van, but if he changed his mind the offer stood, as I was loading the last amp in the van and getting ready to leave, he came out and told me if I wanted them for what we agreed on they were mine!

So I am now the very proud owner of these large and in charge pair of speakers, but as i mentioned earlier there are some issues with these-

four blown tweeters and four blown mid-bass drivers, the tweeters seem to be a common issue, but he midbass drivers are puzzling as they were the ones by themselves listed as the presence drivers that work with the sda feature, I am wondering if by chance they had been wired out of phase causing the damage, I have a local speaker repair guy that has a good reputation that is going to replace the voice coils on the mid-bass drivers, I am going to order the new recommended silk dome tweeters from polk in pairs as I can afford them.

I have a couple questions I am hoping the good folks on here might be able to answer-

1) I already have a nice pair of sl2500 silk dome tweeters from from a pair of polk model 7s, I swapped out two of the blown ones and put the sl2500 as the top set, and put the only working original pair as the 2nd set, unhooked and taped off the leads on the bottom ones for now, I was figuring I would add the new tweeters as I could afford them putting the new ones at the top, the sl2500 tweeters in the middle, and the two tired originals at the bottom till I pu a 2nd pair of the new replacements, then I will put the sl2500 on the bottom, are the sl2500 tweeters an ok alternative to the new ones polk is offering as replacements?

I would have used the two mid bass drivers but the ones from the model 7s are 3ohm and the ones from the 2.3 are basically 6 ohm

2)the prior owner ran the two adcom gfa555 amps in bridged mode, which from what info I can find has these amps putting out around 800 watts to each speaker at the 4ohms they are rated at, and might explain the blown drivers, on the other hand some of the stories he told me might indicate a heavy volume hand might have contributed as well, I am wondering if it would be best to do a vertical biamp instead, using one amp for the top end one amp for the bottom end, I have several pre amps that are designed to be able to do this, this would put the wattage from the amps in stereo mode at 350 wpc, putting 700 watts total to each speaker instead of 800 in bridged mode, and should be an easier load on the amps, one concern I have with the vertical biamp is that I will be putting 350 watts to the top end whereas in a horizontal bridged mode biamp, I am thinking the majority of the power would be taken up with the bottom end, if that makes sense.

I appreciate any help and info others with experience in this can help me with. Thanks Chris

F1nut

By running the Adcom's bridged they became mono blocks and without the AI-1 SDA cable bad juju happened. Do NOT run the amps with those speakers that way. The two dimensional SDA drivers per cabinet do not really work without the SDA cable, do you have the regular SDA cable?

While the SL2500 is similar, it's not the proper tweeter. Use the original SL3000 in the top position.

BTW, I know ya'll talk funny in Ohio, but it's follow and here.

heartystatue

Hey Chris, Welcome to CP. You just got yourself a pair of great sounding speakers. I dont know much about using different ohm replacement speakers temporarily will work but I know you came to the right place to get the answers you seek. If they were mine I would get originals replaced or repaired. The new tweeters are available from polk. RDO-198 is the one for the 2.3tl.. You also need to make sure the amps are common ground. Others will chime in and get you steered in right direction. Good luck!

F1nut

Where did he go???

vintagchris

He is still looking for the sda cable, but I made one out of an rca cable per a recommendation i saw in another thread on this site, to this point after unhooking and taping off the wires on the bad drivers, temporarily installing the two mid bass drivers and two tweeters from the model 7s i have only hooked them up to one amplifier in stereo mode and played them briefly at low volume just to get an idea of how they sound, not going to put big power to them till i get atleast one pair of new tweeters so i have 6 working tweeters and and have the four mid bass drivers repaired.

the reason i put the sl3000 in the middle is the top position seamed to get the most output by design and i think the sl3000 are a bit tired so i figured they would fair better in the middle, eventually i will more than likely end up replacing all six tweeters, but again this was just for a low volume test to see how they were going to perform and to see if they were going to be worth the time and money to restore, and ah...well yeah they definitely are worth the time and money to restore!

vintagchris

thanks guys for the reply's, I already did the common ground amp check, using my ohm meter to determine my amps are common ground style, so i should be good there.

vintagchris

To clarify i pulled all the drivers one at a time and tested them for continuity to determine if they were bad, i am aware the four dimensional drivers wont work without the sda cable, i wish it was as simple as a lack of the sda cable being the issue on those drivers, i am not sure if the prior owner switched drivers around putting all the bad mid bass drivers in the dimensional spot or if for some reason again poss wired out of phase? could have caused this,i was checking out the wiring diagram listed on this site but was having a hard time understanding it.

Nightfall

They're in better hands being with someone that intends to repair them than just sitting unused in somebodies living room anyway. Enjoy!

vintagchris

Amen to that nightfall! my sentiments exactly

F1nut

To clarify i pulled all the drivers one at a time and tested them for continuity to determine if they were bad

Very good, sir.

i was checking out the wiring diagram listed on this site but was having a hard time understanding it.

It's pretty basic. Black or blue is positive, white or green is negative. The red (+) binding posts should be on the left looking at the back.

vintagchris

Thank you very much F1nut, that's very helpful on the color codes on the wires, that is how they were wired, I just wanted to make sure, not knowing whatif any changes the prior owner may have done by accedent switching drivers around.

DarqueKnight

vintagchris wrote: »

2)the prior owner ran the two adcom gfa555 amps in bridged mode, which from what info I can find has these amps putting out around 800 watts to each speaker at the 4ohms they are rated at, and might explain the blown drivers, on the other hand some of the stories he told me might indicate a heavy volume hand might have contributed as well, I am wondering if it would be best to do a vertical biamp instead, using one amp for the top end one amp for the bottom end, I have several pre amps that are designed to be able to do this, this would put the wattage from the amps in stereo mode at 350 wpc, putting 700 watts total to each speaker instead of 800 in bridged mode, and should be an easier load on the amps, one concern I have with the vertical biamp is that I will be putting 350 watts to the top end whereas in a horizontal bridged mode biamp, I am thinking the majority of the power would be taken up with the bottom end, if that makes sense.

Hi Chris. Welcome to the forum.

Do you have the GFA-555, GFA-555 II (Mark II version) or GFA-555SE version? This is important because the original GFA-555 can only be used in bridged mode with 8 ohm speakers. The Mk. II and SE versions can be used with either 4 or 8 ohm speakers in bridged mode.

If you did not receive a manual with the amps, one can be downloaded from the Adcom website: http://www.adcom-usa.com/

The 2.3TL impedance spec says "compatible with 8 ohms", which means its impedance is similar to an 8 ohm speaker's for most of its frequency range, but it can dip low for some bass heavy content and be more like a 6 or 4 ohm speaker. If you have the Mk. II or SE version, this is not a concern.

Regarding your question of bridged mode or biamped, I found that the sound of my GFA-555 Mk IIs "hardened" and became less clear and detailed in bridged mode when used with my SDA 1Cs and SDA 1.2TLs. This was true whether I used the bridged 555 Mk IIs with the SDAs with or without the AI-I non common ground interface cable attached. The clarity and detail was better in bridged mode without the AI-I cable, but, of course, there was no SDA effect. I found that the standard AI-I cable causes some loss of clarity and detail.

I did not try biamping with the 555 Mk. II. I did try biamping with a pair of GFA-5500 amps on my SDA 1.2TLs and there was an improvement:

My-SDA-SRS-1.2TL-Bi-Amp-Adventure

motorstereo

Another thing you might want to check is for dc coming out of those amps. I had a 555 send 6 volts directly to the speaker since there's no protection circuit to stop it. Those drivers are robust and can take lots of abuse but I know I'd be wondering what happened given the amount of damage.
Congrats on picking up one of Polks finest and good luck to you getting them up to snuff.

Mike Reeter

Welcome Chris, Congrats on having a pair of the Polk Audio Classics in your possession, all the mid-drivers in the 2.3TL models are MW-6510, they come up on ebay occasionally. Polk offers replacement drivers that are voiced very close to the original, but have a slightly different appearance.

Good luck on the restoration, you will be rewarded for your efforts.

Mr. Bubbles

welcome to the forum and congrats on the purchase. along the lines of what DK posted; bi-amping would be a better route with those amps and speakers. good luck with the repairs and upgrades that i am sure you will want to do once you get fully involved in the speakers. Enjoy the ride, it can be very addictive.

vintagchris

Thanks guys I appreciate the kind warm welcome and tips.

motorstereo I as well am wondering why the blown drivers, I am going to have to google how to check the dc offset as that is not something I have done before, but I do have a good multimeter to check it with, I am thinking (hoping) that it was more of a heavy volume hand and possibly a little to much power to the speakers in the way he was using the amps that was the culprit, but checking the dc output on the amps is definitely on my tado list.

Mike reeter thanks for the midbass driver info, I was wondering if polk had a replacement available, I'm gonna give my local speaker tech a crack at replacing the voice coils in the originals first if that doesn't work out to my satisfaction its good to know there's new compatible replacements available.

vintagchris

Oh almost forgot, my amps are unfortunately the earlier adcom gfa555 not the later II or se models, later this evening when I get home from work, I will post some other amp options I own that might be a better option and get your guys opinions, when I went to look at these amps and stumbled onto the speakers, my intentions for the amps were not to drive my main speakers but to use with a pair of custom subwoofers I was wanting to build.

Polkie2009

Congrats on the SDA's vintagchris, and welcome to CP. Those older Adcom GFA-555 can hold their own, just may need caps replaced when they go bad. Let us know what other amps you have available.

westmassguy

vintagchris wrote: »

Thanks guys I appreciate the kind warm welcome and tips.

motorstereo I as well am wondering why the blown drivers, I am going to have to google how to check the dc offset as that is not something I have done before, but I do have a good multimeter to check it with, I am thinking (hoping) that it was more of a heavy volume hand and possibly a little to much power to the speakers in the way he was using the amps that was the culprit, but checking the dc output on the amps is definitely on my tado list.

Mike reeter thanks for the midbass driver info, I was wondering if polk had a replacement available, I'm gonna give my local speaker tech a crack at replacing the voice coils in the originals first if that doesn't work out to my satisfaction its good to know there's new compatible replacements available.

Hi Chris and welcome to Club Polk. Very doubtful your local guy will be able to change the voice coils. Polk woofers are rather unique. There are several different 8 ohm models. Although they may have the same 8 ohm nominal rating, they have very different T/S parameters. You can't put a generic 8 ohm voice coil in there and expect it to perform as original. In addition, the rubber surrounds alone will be difficult to remove to gain access to the spider. As Mike pointed out, eBay, or direct from Polk Customer Service. If you do go with eBay, be sure to work with the seller on packing them properly, as the vintage woofers do not like being thrown around during shipping. You may end up with "Magnet Shift", which makes them into nice paper weights.

vintagchris

westmassguy wrote: »

Hi Chris and welcome to Club Polk. Very doubtful your local guy will be able to change the voice coils. Polk woofers are rather unique. There are several different 8 ohm models. Although they may have the same 8 ohm nominal rating, they have very different T/S parameters. You can't put a generic 8 ohm voice coil in there and expect it to perform as original. In addition, the rubber surrounds alone will be difficult to remove to gain access to the spider. As Mike pointed out, eBay, or direct from Polk Customer Service. If you do go with eBay, be sure to work with the seller on packing them properly, as the vintage woofers do not like being thrown around during shipping. You may end up with "Magnet Shift", which makes them into nice paper weights.

I would tend to agree with you but this guy isn't your normal speaker repair guy, in our area hes well known and has a a very good reputation for driver repairs and rebuilding, and when i talked to him he said he had done a good many polk drivers like these, but having said that I have been thinking about it some today, and admittedly I am a little worried I could be throwing good money after bad, he wants 40 dollars apiece to repair them, I need to see what the new replacements cost is, I seen the new replacement tweeters are around 50 bucks apiece, if the midbass drivers are close to that price range it would seem a no brainer to go with new.

westmassguy

DSkip wrote: »

They are, go new.

^^^^^^^^^^^ This!
I re-cone and re-foam for living. There's no way they'd be a match for used replacements, or the new replacements. $48.00 plus tax with free shipping. Be sure to tell them you're a member of Club Polk

PolkieMan

Welcome!
I would go with all new MW 6510 drivers from Polk to replace the four bad ones
since they are all dimensional drivers. Last time I checked they were only
$48 free shipping +tax. Since the tweeters are are bad I would go ahead and replace all 6 of them
$48 free shipping +tax, tell them that you are a "Club Polk" member for the discount pricing. I have
a set of these new in July 1990.
BTW you really won't need a subwoofer anymore.

vintagchris

48 bucks I'm sold! new it is

Nightfall

Another vote for buying new. No sense in repairing them and they wouldn't be the same with a replacement voice coil anyway.

PolkieMan

Yea of course I don't know what their stock is so don't get mad at me if you have to wait a while.
I always keep a spare too the beauty of these in that they are all 6510 drivers most SDA's use 2 different models.

Sda Handbook http://vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf

vintagchris wrote: »

48 bucks I'm sold! new it is

F1nut

vintagchris wrote: »

48 bucks I'm sold! new it is

Be aware that the new drivers look a bit different and you will have to cut a notch in the rubber surrounds at each screw hole. Check eBay for used original MW6510's, they usually run about $30 to $35 each.

vintagchris

PolkieMan wrote: »

Yea of course I don't know what their stock is so don't get mad at me if you have to wait a while.
I always keep a spare too the beauty of these in that they are all 6510 drivers most SDA's use 2 different models.

Sda Handbook http://vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf

All good Polkieman, and everyone else who weighed in on whether or not to rebuild the origonal drivers, I value your opinions and appreciate the heads up on the price of the new drivers.

And thanks to Darquenight for the linc to your thread on biamping and bridging, and everyone else who weighed in on my question as to biamp or bridge, the last couple days I have been running the adcom amps in my test rig and both amps are working fine and sound good, but the lack of gain control is one issue I have with these amps, as others suggested i am going to test the DC offset on the adcoms, I am a member over at audiokarma and I checked out echowars sticky thread on checking dc offset and seems pretty strait forward and something I can do.

As I mentioned earlier today I have other amp options that might be a better fit for these speakers, my main reason for buying the adcoms was to use them bridged on a pair of custom subwoofers i was wanting to build, here are two other options i could use.

option 1- is the adcoms vertical biamped with one amp powering the the top end one amp powering the bottom end, this should show a safer ohm load to the amps and a more speaker friendly power output, as compared to bridged as the original owner had used them, more than likely though these amps are going to be ebayed to fund the polk speaker restoration.

option 2- is my pair of sherwood am-7040 duel mono block, mosfet amps, this is more than likely they way i will go, again with a vertical biamp as these are not bridgeable anyways, these are the same power output as the adcoms 200 watts per channel at 8ohms and 350 at 4ohms, very clean smooth sounding amps, i did a side by side comparison to one of the adcoms last night in my main rig and it was no contest the sherwoods are just a better quality and sounding amp, which they should be they were ro double the price the price of the adcoms new.

option 3- is my single yamaha p-2200 amp, again same watts as the adcom and sherwoods, very clean uncolored sounding amp with loads of headroom,this amp is capable of running tough loads with ease, this amp has run some tough to drive inefficient speakers for me (dahlquist dq10s, maganapans) like no other single amp I have owned, sherwoods included.

heres some pictures of the candidates-

vintagchris

Well houston we may have a problem, I figured I better check if my sherwoods and yamaha amps are common ground amps, the yamaha amp read zero accross the grounds on the ohm meter, but the sherwoods read 00.1, I checked both sherwood amps and they read the same

PolkieMan

B safe use the Yamaha, at least for now.

Did you download this?

Sda Handbook http://vr3mods.com/uploads/SDA_Handbook_2011_Rev2.pdf

gmcman

Late welcome but congrats on the 2.3's, they are on my wish list for sure. Hope you get them all fixed up, lots of great people here to help.

vintagchris

F1nut wrote: »

Be aware that the new drivers look a bit different and you will have to cut a notch in the rubber surrounds at each screw hole. Check eBay for used original MW6510's, they usually run about $30 to $35 each.

F1nut can you elaborate on the notching the surround, are you just talking the outer edge of the surround that's glued to the basket, surely your not talking the actuall role itself right ?