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

TennMan

vintagchris wrote: »

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 ?

He's talking about cutting away a small section of rubber that would otherwise be between the screw head and the metal frame of the speaker (basket). If you tighten the screw down on the rubber it will start twisting with the screw and pull the rubber loose from the basket or at least distort it where it won't seal properly.

westmassguy

TennMan wrote: »

He's talking about cutting away a small section of rubber that would otherwise be between the screw head and the metal frame of the speaker (basket). If you tighten the screw down on the rubber it will start twisting with the screw and pull the rubber loose from the basket or at least distort it where it won't seal properly.

Correct. I found the easiest way to make the cut, is with an sharp exacto knife, scalpel, or utility knife blade, with 3/4s of the blade taped off. The old drivers have a squared off notch. You can try and duplicate that, or what I do, is find a round or pan head screw that fits snugly through the mounting hole. Then just run the knife around the edge of the screw head that overlaps the rubber surround. Try it on the old driver first, and see if it removes enough rubber. Try several different size screws/screw heads if you have to. You don't want to get too close to the roll, and the inner edge, you want to remove just enough rubber so the screw won't catch on it when your mounting the drivers. That's one of the weak points on the drivers. I've seen cracks starting right where the notch is on older drivers.

vintagchris

Oh ok thanks, a nylon or plastic washer should take care of that issue, I would like to lay eyes on these drivers and see how much different they look, theres nothing on ebay at the moment, if all else I might just order the four I need till I find origonals and then pass the replacements onto another member in need

Schurkey

vintagchris wrote: »

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

One-tenth of an ohm? I wouldn't expect that to be a problem. 20 ohms is a problem.

TennMan wrote: »

He's talking about cutting away a small section of rubber that would otherwise be between the screw head and the metal frame of the speaker (basket). If you tighten the screw down on the rubber it will start twisting with the screw and pull the rubber loose from the basket or at least distort it where it won't seal properly.

One wonders: why wouldn't Polk insist their supplier fix that?

westmassguy

Schurkey wrote: »

One wonders: why wouldn't Polk insist their supplier fix that?

True, but let's be thankful Polk cares enough to still supply the correct replacement drivers for us. Not many companies do.

vintagchris

Schurkey wrote: »

One-tenth of an ohm? I wouldn't expect that to be a problem. 20 ohms is a problem.


One wonders: why wouldn't Polk insist their supplier fix that?

I wondered the same thing on the tenth of an ohm on reading on my sherwoods, I do know mosfet outputs are very suseptical to damage if shorted, kinda weird though, when you first touch the probes to the grounds both amps zero out for a second than go to the 00.1 reading, I got the manual out and it doesn't say anything about them being common ground or not.

vintagchris

Alright sorry if I'm being dense but just to clarify, on the whole common ground amp thing, I am wanting my amp to read continuity across the grounds but show zero on my multimeter for it to be ok to use the sda cable?

vintagchris

I just sent an email to sherwoods support department to see if they could answer wether or not my am7040 amps are common ground amps, hopefully they will get back to me with an answer....

Schurkey

vintagchris wrote: »

I am wanting my amp to read continuity across the grounds but show zero on my multimeter for it to be ok to use the sda cable?

I'd have called them the negative speaker-wire terminals, but yes, I have every expectation that 0.1 ohms is close enough.

vintagchris wrote: »

I just sent an email to sherwoods support department to see if they could answer wether or not my am7040 amps are common ground amps, hopefully they will get back to me with an answer....

Far as I'm concerned, you've already answered that.

You want to absolutely, positively eliminate the possibility of problem? Stuff a jumper wire between the negative speaker-wire terminals of the two channels. Your amps aren't bridged/balanced, or you'd have more than 0.1 ohms between the negative terminals.

vintagchris

Well surprisingly sherwood already emailed back, this is excactly what they said let me know what you guys make of this

"I had a conversarion with polk audio support, they said this amp the am7040 should be compatible, our receiver is not common ground type, but they tell me all you need to do is extend the negative right and left speaker connection, you will need to contact polk for support"

vintagchris

Sorry you will have to forgive me if i seem overly concerned but these amps are my baby's and if I was to fry them I would be screwed as the only reputable repair tech is ro three hrs from me, and from past experience it would be a garrenteed minimum of 300 dollars for a repair

PolkieMan

You were concerned about the newer drivers looking different that the vintage there is a slight difference in the appearance of the cones texture and the voice coil wires are hidden on the new ones.
If you use the new ones for the dimensional drivers it will look fine.

here is what the new ones would look like
http://www.ebay.com/itm/2-NEW-Polk-Audio-Monitor-Series-5-1-4-woofer-MW6517-M5-M7-M10-RM100SPEAKERS-/350916731517?pt=Speakers_Subwoofers&hash=item51b444627d

Schurkey

vintagchris wrote: »

Well surprisingly sherwood already emailed back, this is excactly what they said let me know what you guys make of this

"I had a conversarion with polk audio support, they said this amp the am7040 should be compatible, our receiver is not common ground type, but they tell me all you need to do is extend the negative right and left speaker connection, you will need to contact polk for support"

Schurkey wrote: »

You want to absolutely, positively eliminate the possibility of problem? Stuff a jumper wire between the negative speaker-wire terminals of the two channels. Your amps aren't bridged/balanced, or you'd have more than 0.1 ohms between the negative terminals.

Your amp has common-ground or you'd have more than a tenth of an ohm between the negative terminals. Shove the jumper wire into position and enjoy.

One wonders why Sherwood is telling you the amp isn't common-ground. First Guess: Customer Service doesn't actually know, and they didn't bother to contact Engineering.

vintagchris

PolkieMan wrote: »

You were concerned about the newer drivers looking different that the vintage there is a slight difference in the appearance of the cones texture and the voice coil wires are hidden on the new ones.
If you use the new ones for the dimensional drivers it will look fine.

here is what the new ones would look like
http://www.ebay.com/itm/2-NEW-Polk-Audio-Monitor-Series-5-1-4-woofer-MW6517-M5-M7-M10-RM100SPEAKERS-/350916731517?pt=Speakers_Subwoofers&hash=item51b444627d

Thank you very much! somehow I missed those, that settles it for me on this issue, those look fine to me and as you mentioned I will just put those in the dimensional driver locations and call that done, same with the tweeters i need, personally I would rather have new anyway than used ones that may or may not be up to par, and the used ones would probably cost me close to what the new ones cost anyway.

PolkieMan

Remember those I showed you was just for the show pictures, your must get MW6510 for replacements

vintagchris wrote: »

Thank you very much! somehow I missed those, that settles it for me on this issue, those look fine to me and as you mentioned I will just put those in the dimensional driver locations and call that done, same with the tweeters i need, personally I would rather have new anyway than used ones that may or may not be up to par, and the used ones would probably cost me close to what the new ones cost anyway.

vintagchris

Schurkey wrote: »

Your amp has common-ground or you'd have more than a tenth of an ohm between the negative terminals. Shove the jumper wire into position and enjoy.

One wonders why Sherwood is telling you the amp isn't common-ground. First Guess: Customer Service doesn't actually know, and they didn't bother to contact Engineering.

Right i agree, was it just me though or was the way they worded their response although appreciated a bit confusing, they mention the amp specifically and say it "should be" compatible, but then go on to say their receivers (which i hadnt asked about) are not common ground and describe how to address it, thats what threw me, I understand what your telling me on the jumper wire, but I didnt understand what they meant by "extend the negative right and left speaker connection"

vintagchris

PolkieMan wrote: »

Remember those I showed you was just for the show pictures, your must get MW6510 for replacements

Right i understand, from what you guys had told me earlier I realized they were cheaper with the membership discount and free shipping directly from polk than those were listed for anyway

PolkieMan

If they were shorted out thus blowing the MW drivers have you looked at the crossovers yet?

vintagchris wrote: »

Right i understand, from what you guys had told me earlier I realized they were cheaper with the membership discount and free shipping directly from polk than those were listed for anyway

vintagchris

PolkieMan wrote: »

If they were shorted out thus blowing the MW drivers have you looked at the crossovers yet?

I have and I didn't see any signs of overheating on the coil resisters, or any dark spots on the caps, or anything else that looked suspicious, as i mentioned I temporarily swapped in my sl2500 tweeters and two midbass drivers from my model 7s which left me one tweeter and one midbass driver still bad but wires unhooked in each speaker, just so i could get an idea how they would sound and they sound very crisp and clean with no upper frequency siblence or noticeable distortion i have heard on other speakers i have owned that did have crossover issues, but a crossover rebuild is on my list to do, but will have to wait till i can swing it.

I am thinking the prior owner mentioning his neighbors complaining a half mile away when he cranked them up might possibly explain the bad drivers, but could have been the amps as well, when i tried one of the two adcom amps i got off him on them it didnt sound all that clean like my nad 2600 or my scs pro amp i tried on them did, so there could be a dc offset issue with the adcoms that could have been the cuprit,I googled how to check the dc offset but i haven't taken the time to check them for that yet as i really don't plan on using them on these anyway.

TennMan

vintagchris wrote: »

...
I am thinking the prior owner mentioning his neighbors complaining a half mile away when he cranked them up might possibly explain the bad drivers, but could have been the amps as well, when i tried one of the two adcom amps i got off him on them it didnt sound all that clean like my nad 2600 or my scs pro amp i tried on them did, so there could be a dc offset issue with the adcoms that could have been the cuprit,I googled how to check the dc offset but i haven't taken the time to check them for that yet as i really don't plan on using them on these anyway.

Please post the dc offset numbers when you test your Adcoms. I have a gfa555 and would like to see how your numbers compare to mine.

vintagchris

Well now its a waiting game, I have some of my audio collection listed locally to fund the repairs on these, its that time of year where works starting to slow down and i blew all my mad money just getting these and the amps, just gonna take my time and do them right as i have the funds.

I was reading the crossover rebuild thread in the do it yourself threads, this is something i would like to do as well, or rather i should say have the one member, and i apologize i should a wrote his name down, but would like to have the one member who was doing some stellar looking rebuilds in the thread i was reading do them for me.

But I have been spending some time listening to them at moderate levels, pink floyd last night sounded absolutely amazing! even in there current condition i really like these allot, that's a testament to the quality of these, I have some pretty nice speakers to compare them to.

gmcman

vintagchris wrote: »

I was reading the crossover rebuild thread in the do it yourself threads, this is something i would like to do as well, or rather i should say have the one member, and i apologize i should a wrote his name down, but would like to have the one member who was doing some stellar looking rebuilds in the thread i was reading do them for me.

When you get everything together for the crossover, I would absolutely add a pair of Gimpod's boards into the build if you can. No better way to start fresh and using a board setup for the Sonicaps is the way to go. I used these boards for my 2B and the layout was perfect. If you get all the parts with thise boards and ship them to me I would be happy to solder them up for you.

vintagchris wrote: »

But I have been spending some time listening to them at moderate levels, pink floyd last night sounded absolutely amazing! even in there current condition i really like these allot, that's a testament to the quality of these, I have some pretty nice speakers to compare them to.

Yeah, Floyd sounds great on SDA's for sure. Ironically before I read this post, my 5YO came into the room and shuffled through the CD's. Not knowing what any of them say, he grabbed Delicate Sound of Thunder and wanted to hear it...lol.

So needless to say that's what we're listening to right now.

vintagchris

gmcman wrote: »

When you get everything together for the crossover, I would absolutely add a pair of Gimpod's boards into the build if you can. No better way to start fresh and using a board setup for the Sonicaps is the way to go. I used these boards for my 2B and the layout was perfect. If you get all the parts with thise boards and ship them to me I would be happy to solder them up for you.




Yeah, Floyd sounds great on SDA's for sure. Ironically before I read this post, my 5YO came into the room and shuffled through the CD's. Not knowing what any of them say, he grabbed Delicate Sound of Thunder and wanted to hear it...lol.

So needless to say that's what we're listening to right now.

Ahhh, I sense you have a future audiophile there, thanks for the offer on the crossovers i appreciate that.

vintagchris

Alright took some time to check the DC offset on my two adcom gfa-555 amps

amp 1- right channel=11.8 left channel=33.7

amp 2- right channel=32.2 left channel=5.8

note- both amps when tested were hooked up at the same time to the main1 and main2 output from a carver C1 pre amp, tone controls on pre amp were defeated and volume all the way down, source set to aux 2 which has nothing tied into it at the moment.

What do you guys make of these readings, seems to be a substantial difference in both amps from one side to the other.

TennMan

I've tested mine with my preamp set to 0 volume and input set to aux which has nothing connected to it. All tone controls set flat.

From what I've read 10mv on both sides would be perfect. Anything below 40mv is OK. Readings near 50mv and higher need to be checked out. I hope some other gfa-555 owners will report their results for comparison.

LEFT: 37.7mv
RIGHT: 18.3mv

Schurkey

Instructions for Aragon amps say to run the amp for four hours, then short the amp input before measuring/adjusting the DC offset. I'd hate to see the amp being adjusted because there's an offset problem higher up the chain.

Spec for the Aragon is LESS THAN + or - 0.01v (10mv), therefore some of your results would be "way out"--but I don't know what the Adcom specs are.

gimpod

vintagchris wrote: »

Alright took some time to check the DC offset on my two adcom gfa-555 amps

amp 1- right channel=11.8 left channel=33.7

amp 2- right channel=32.2 left channel=5.8

note- both amps when tested were hooked up at the same time to the main1 and main2 output from a carver C1 pre amp, tone controls on pre amp were defeated and volume all the way down, source set to aux 2 which has nothing tied into it at the moment.

What do you guys make of these readings, seems to be a substantial difference in both amps from one side to the other.

TennMan wrote: »

I've tested mine with my preamp set to 0 volume and input set to aux which has nothing connected to it. All tone controls set flat.

From what I've read 10mv on both sides would be perfect. Anything below 40mv is OK. Readings near 50mv and higher need to be checked out. I hope some other gfa-555 owners will report their results for comparison.

LEFT: 37.7mv
RIGHT: 18.3mv

To began with to check the DC offset on those ADCOM GFA-555's it should be done cold with nothing connected to the input or output also there is no DC offset adjustment for these amps. FYI There is a whole bunch of info on these amps over at www.diyaudio.com do a search.

Schurkey wrote: »

Instructions for Aragon amps say to run the amp for four hours, then short the amp input before measuring/adjusting the DC offset. I'd hate to see the amp being adjusted because there's an offset problem higher up the chain.

Spec for the Aragon is LESS THAN + or - 0.01v (10mv), therefore some of your results would be "way out"--but I don't know what the Adcom specs are.

Sure your not talking bout DC Bias, I know each amp is different but that's what it sounds like to me.

Schurkey

Schurkey wrote: »

Instructions for Aragon amps say to run the amp for four hours, then short the amp input before measuring/adjusting the DC offset. I'd hate to see the amp being adjusted because there's an offset problem higher up the chain.

Spec for the Aragon is LESS THAN + or - 0.01v (10mv), therefore some of your results would be "way out"--but I don't know what the Adcom specs are.

gimpod wrote: »

Sure your not talking bout DC Bias, I know each amp is different but that's what it sounds like to me.

My info is for the Aragon 4004 or 2004.
Bias is set by measuring across one of the emitter resistors; bias adjustment pot is then set to achieve 10mv plus or minus 2mv.
DC offset is set by measuring at the output terminal, adjusting a different pot, 0.00 plus or minus 0.01 mv.

vintagchris

gimpod wrote: »

To began with to check the DC offset on those ADCOM GFA-555's it should be done cold with nothing connected to the input or output also there is no DC offset adjustment for these amps. FYI There is a whole bunch of info on these amps over at www.diyaudio.com do a search.




Sure your not talking bout DC Bias, I know each amp is different but that's what it sounds like to me.

Well I checked it the way you said to, cold, no pre amp, nothing tied into the inputs or outputs, gotta say I liked my way better, these readings are a little scarier than my earlier readings.

Amp 1- right channel 30.3 left channel 62.0
Amp 2- right channel 64.0 left chsnnel 25.6

And i assure you I had no intentions of trying to do any adjusting on these amps, I leave that type of work to somoene more qualified, I was just hoping that was not going to be neccessary, but its looking likely that's what needs to happen, and could explane the blown drivers

gimpod

Mine checked out at

Right Chanel = -65mv DC
Left Chanel = -42mv DC

And and was told that it was not too bad and has been running like that for over a year without a problem. Oh like I said before there is no adjusting the DC offset on these amps without parts matching and replacing.

Read this:

http://www.diyaudio.com/forums/solid...rements-4.html

You can backtrack the thread but the post by ostripper says what a normal offset is. And from his previous posts he sounds like he knows the 555., Warning I have not tried it.