SDA with Interconnect with Carver M 400
VSAT88
Posts: 1,257
Would someone please answer a question. I have two M 400A Carver amps, from what I can tell the M 400A is a common ground amp and can be used with the SDA 2b speaker with the interconnect..Yes..No ?? What about using two as Mono blocks one for the left SDA and one for the right..With the interconnect..Can this be done ? Please tell me, Thanks !
Comments
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Use a multi-meter to test for common ground between the negative binding posts....wait, those are spring clips.
The only way to use mono blocks is with the AI-1 or Dreadnought isolation transformer, assuming your 2B's are pin/blade. But wait, bridged amps don't like anything below 8 ohms and the 2B's are 6 nominal and dip lower.
Personally, I think that is Carver's worst sounding SS amp. Use the Pioneer SPEC or Fisher instead.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Use a multi-meter to test for common ground between the negative binding posts....wait, those are spring clips.
The only way to use mono blocks is with the AI-1 or Dreadnought isolation transformer, assuming your 2B's are pin/blade. But wait, bridged amps don't like anything below 8 ohms and the 2B's are 6 nominal and dip lower.
Personally, I think that is Carver's worst sounding SS amp. Use the Pioneer SPEC or Fisher instead.
F1 I appreciate you more than you know. You are crafty. You know this business inside and out. I have been on a lot of different forums and I really like this one best. I always double check my "logic" here. I have a problem with my thinker so I like a double check..Getting old and a lot of meds didn't help...I really do appreciate you Guys/Gals here at Club Polk. -
This is a problem I had a quarter century ago with a pair of SDA-1B's and a pair of M-400t's (*same amp cube,just transfer function calibrated to some other amp and darker gray in color.Not sure which amp though*)I kept getting all kinds of confusing information from all over the place about whether or not that amp could drive Polk SDA's. I was SO confused that I wrote a letter to Bob Carver and MUCH TO MY SURPRISE,HE ACTUALLY WROTE ME BACK!!!
By shear coincidence (*and for your shopping convenience*) I happen to still have that letter dated August 20 1987 RIGHT HERE.
To give you a synopsis of what he said.
Only the left channel of each cube is common grounded. So use one cube per channel using only the left channel of each cube to get the common grounding. Also use a heavy wire between the two black chassis terminals of the two amps to lock the grounds together.
The unused power from the right channels with largely be available to kind of be borrowed by the left channels. Granted it won't be the full 500 watts per channel bridged.It will be about 300 to 350 watts per channel.
He advised against bridging the amps,because then it makes the grounding issue impossible to deal with.
The only SDA-2's that could use the AI-1 non common ground interface are the last generation ones that looked like Vandersteens if memory serves (*Check with Polk to be sure*) So this solution is really about the only one you can use for now.It worked for me 23 years ago with the SDA-1B's even before the non common ground interface was available.
Good luck!
Carlton
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honestaquarian wrote: »This is a problem I had a quarter century ago with a pair of SDA-1B's and a pair of M-400t's (*same amp cube,just transfer function calibrated to some other amp and darker gray in color.Not sure which amp though*)I kept getting all kinds of confusing information from all over the place about whether or not that amp could drive Polk SDA's. I was SO confused that I wrote a letter to Bob Carver and MUCH TO MY SURPRISE,HE ACTUALLY WROTE ME BACK!!!
By shear coincidence (*and for your shopping convenience*) I happen to still have that letter dated August 20 1987 RIGHT HERE.
To give you a synopsis of what he said.
Only the left channel of each cube is common grounded. So use one cube per channel using only the left channel of each cube to get the common grounding. Also use a heavy wire between the two black chassis terminals of the two amps to lock the grounds together.
The unused power from the right channels with largely be available to kind of be borrowed by the left channels. Granted it won't be the full 500 watts per channel bridged.It will be about 300 to 350 watts per channel.
He advised against bridging the amps,because then it makes the grounding issue impossible to deal with.
The only SDA-2's that could use the AI-1 non common ground interface are the last generation ones that looked like Vandersteens if memory serves (*Check with Polk to be sure*) So this solution is really about the only one you can use for now.It worked for me 23 years ago with the SDA-1B's even before the non common ground interface was available.
Good luck!
Carlton
That my friend is just awesome. It seems as if we pulled a similar trick with a car stereo amp back in the day..Just to make sure I understand..On both amps I should use a heavy wire from both black terminals connected to the other amps two black terminals and wire the speakers to the left terminals only off each amp..Right ? -
NO. Your ground strap goes from the LEFT negative terminal of one amplifier to the LEFT negative terminal of the other amplifier. DO NOT connect to the RIGHT negative terminal of either amplifier.
You could also connect your jumper cable directly to a well-grounded chassis screw or somesuch on each amplifier, but the LEFT negative terminal is far more convenient.
A third option would be to connect your input and output cables to the LEFT channels of the two amplifiers, route the SDA cable between the two speakers, then connect the negative terminals of the SPEAKERS together with your jumper wire. Depending on where you locate the amplifiers, this may require a much longer jumper as the speakers will be many feet apart, while the amplifiers could potentially be right next to each other. -
NO. Your ground strap goes from the LEFT negative terminal of one amplifier to the LEFT negative terminal of the other amplifier. DO NOT connect to the RIGHT negative terminal of either amplifier.
You could also connect your jumper cable directly to a well-grounded chassis screw or somesuch on each amplifier, but the LEFT negative terminal is far more convenient.
A third option would be to connect your input and output cables to the LEFT channels of the two amplifiers, route the SDA cable between the two speakers, then connect the negative terminals of the SPEAKERS together with your jumper wire. Depending on where you locate the amplifiers, this may require a much longer jumper as the speakers will be many feet apart, while the amplifiers could potentially be right next to each other.
Got ya, I just have to try this and see what it sounds like. I will get back with you all to let you know what happens. Thanks all. -
Well seems as if I got the wagon before the horse. I bought a great deal of equipment in one lot and the person told me I was getting three M 400s and that two worked the third did not. Now I find that two do not work and the third does so I am unable to try the above fix. Thanks for all your help and I will continue till I get an amp that can do these speakers justice.
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Oy vey!!
Well you COULD use that one amp to drive the SDA's.Just NOT with the interconnect cable hooked up!!!!
Or how about that Parasound amp? -
Yes, the Parasound. I am using it right now . I have posted another thread today about how to wire my SDA IIb speakers to an isolation transformer as I want to build one however I am clueless as of how to wire it. My SDAs are blade blade and only one wire is active..Thanks !
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Yes, the Parasound. I am using it right now . I have posted another thread today about how to wire my SDA IIb speakers to an isolation transformer as I want to build one however I am clueless as of how to wire it. My SDAs are blade blade and only one wire is active..Thanks !
That is the case with pretty much all of the SDA's having only one wire active.The other blade or pin was to keep the cable in place. As for the non common grounding interface,you can ONLY use that on the last generation SDA's as Polk made changes to the crossovers to allow for that and make them easier to drive. I could be wrong,but my understanding for the SDA-2's is the only ones which could accomodate the non common ground interface were the last ones which had the new cabinets that made them look like Vandersteens and had a Pin/blade crossfeed cable. -
There's some incorrect info above, but I don't have time right now to straighten it out.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Ok, VSAT88 please use the proper model, which would be SDA 2B. So, all blade/blade models use two wires, both the large and small blades carried a signal. In the later pin/blade models only the pin carried a signal except if you were using the AI-1 in which case both carried a signal. With the exception of the early blade /blade 2B's none of the other blade/blade models can be configured to use non-common ground amps.Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
Jesse, correct me if I'm wrong: I believe that on the Blade/blade 2B's the large blade just 'floated', and had no electrical connection.
Posted this in another thread tonight:
Jay
SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0 -
Yeah Jay, that's correct, but I do not consider the 2B's to be blade/blade models.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk -
You are really correct--all designed as pin/blade, just happened to have the blade/blade hardware.
Jay
SDA 2BTL * Musical Fidelity A5cr amp * Oppo BDP-93 * Modded Adcom GDA-600 DAC * Rythmik F8 (x2)
Micro Seiki DQ-50 * Hagerman Cornet 2 Phono * A hodgepodge of cabling * Belkin PF60
Preamp rotation: Krell KSL (SCompRacer recapped) * Manley Shrimp * PS Audio 5.0 -
http://forum.polkaudio.com/discussion/131691/2b-and-early-1c-ai-1-modifications#latestI have posted another thread today about how to wire my SDA IIb speakers to an isolation transformer as I want to build one however I am clueless as of how to wire it. My SDAs are blade blade and only one wire is active..Thanks !
The SDA 2 blade/blade and the SDA 1C blade/blade are easily configured to work with an isolation transformer. There are many ways to do this, all of them depending on what style of connector you want to use to hook-up the two wires per cabinet needed by the transformer.
A "SpeakOn" connector seems to be the favored method, but it would be possible to use other connectors just as successfully--if not as aesthetically pleasing.
The "ground" wire from the isolation transformer can be connected directly to the negative binding post. The "hot" wire from the isolation transformer would go to the wire that is currently connected to the "pin" of your pin/blade connector.
