amp for my SDA-1A's

[g-man]

Hi,I know you'd read this F1nut,and I have a question.You said that I shouldn't use a non-common ground amp for my SDA-1A's,nor should I use mono blocks...why..? Is it because of the interconnect cabel between the speakers? I can't seem to find any other reason than that..

G-man

[Tour2ma]

Yup... the standard SDA interconnect establishes a circuit connecting the grounds of the left and right channels. To an amp (or amps) that cannot tolerate that, it's a short, and those are never good.

Most 2-ch amps are common ground designs, but not all are.

Some Mono-blocks can handle their negative (or ground) speaker terminals) being wired together, but not all can.

What amp(s) do you have in mind?

[g-man]

I've been looking at many different amps such as the Meridian 557,the Electrocompaniet AW120,Pas Lab,McIntosh, and a Carver amp..(F1nut recomended a carver,but I'm not sure where to get one here in Norway).But the one I'd like to have is the McIntosh or the Meridian.Theesa amps costs allot,so I'm looking for a used one..can't buy them from the US because of the voltage isn't the same..(240V here.)

G-man

[Tour2ma]

NAD should be avaialble to you. They're a good choice and an UK company.

Fair amount of used 2-ch availability, at least over here...
http://www.nadelectronics.com/index.htm

[g-man]

There's allot of used NAD's here,but do you think they have what it takes to reproduse a natural sound..? I have owned several NAD's thru the years,but I think that the SDA's could use a better amp..The only amp from NAD could be the Silverline S300.It delivers 2x100W in 8 ohms.Do you think that's enough..?
How about the Meridian 557..?
Or the McIntosh MC275..?

G-man

[F1nut]

Hey G-man, I recommended a Carver? I don't recall that....lol.

I think either one of your other choices would work well, especially the tubed Mac.

[g-man]

ooops..! sorry F1nut..my bad...Cary V12..missread.I'm Norwegian for crying out loud..!! :D but anyways..you think the Meridian is a good one..? I've listen to the Meridian on a pair of JMLab Electra and man did that sound great.! The Mac is just a wet dream actually...very hard to find a used one here and they cost alot,but I have the Meridian 557 power amp and the Meridian 501 (or the 861) pre-amp available at a store close by..going to visit the store monday morning when they open..with a fist full of cash..lol..

again..thanks guys.

G-man

PS..

what do you think of my home theatre system..had it for 3 years now..still going strong..:)

[reeltrouble1]

Let me add to Tour2ma suggestion for the NAD, I have used the 2600A and 2700 with excellent results on my 1C's. You want something that will push something around 200 wpc at high current into the 1A which are nominal 4 ohm speakers.

Many folks here use Carver and Parasound to drive their SDA and report excellent results.

RT1

[F1nut]

G-man,

Meridian makes great gear, but I think you're going to have a problem with the 557 because it's dual mono and might not be a common ground amp. You can not use a non-common ground amp with those SDA speakers. You should check with your dealer and/or Meridian about that situation.

Sorry, I should have mentioned this earlier.

[g-man]

I'm glad that some know more about amps than me...:D I've never had to check how they are built before,but since I now have a pair of "rare" loudspeakers,I should check this out from now on..
Got another amp suggestion: The Rotel RB990BX and the Rotel RA950RTC pre-amp..? The guy who's selling them wants $890 for them.Mint condition.

G-man

[Tour2ma]

Rotel amps have a good following around here. Nice, high current designs... At 200 wpc the 990 should be more than enough for the 1A's.

I have no knowledge, 2nd hand or otherwise, of the pre....

Stateside, looks like $875 would be on the high side for that combo. Mint, the amp looks to go in the $400 to $450 range, and the pre in the mid-200's.

[patwhite]

I am the owner of an nad 2200pe...plenty of power, but it can only be used with speakers that are non common ground since this amp can be bridged to become a mono amo....at one time, polk would swap out the connecting cable with one that could be used for non common ground amps.

[F1nut]

Hold on Pat, your NAD is a common ground amp and only becomes a non-common ground amp if it's bridged. The cable you're speaking of is called the AI-1, but it can't be used with G-man's speakers.

[patwhite]

my owners manual clearly says don't use the 2200 nad amp with speakers that share a common ground....case in point, a friend of mine years ago with the same amp bought a pair of sda 2b's hooked them up to the nad using the provided interconnect and promptly blew the tweeters...we went back to the store and the salesman who just happened to have sold NAD in the past had the lightbulb go off and said..wrong interconnect..got the right one, hooked em up...no problems...

[hoosier21]

Originally posted by patwhite
my owners manual clearly says don't use the 2200 nad amp with speakers that share a common ground....

That is very interesting, I have had Polk SDA's and about every NAD amp including the 2200, never had a problem, not 100% sure I used the 2200 with SDA's, but I can't imagine I didn't.

The later models, of NAD 2700, 2600, 2400, 2100 have all been used with SDA's with no problem.

Like I said interesting stuff on the 2200.

[F1nut]

Ok, a quick search around the net didn't give me much, so from what you're saying this NAD is a dual mono amp and that it can be bridged?

[hoosier21]

Inverted channels for powerful bass
The greatest power demands commonly occur at low frequencies. Bass signals are in phase (and virtually
monophonic) in most recordings; thus when the bass waveform is strongly positive in the left channel, it
usually is strongly positive in the right channel at the same time. As a result both channels draw current
simultaneously from the positive half of the power supply, while the negative half sits idle. During the
negative half of the waveform, both channels draw from the negative supply while the positive supply
sits idle. In the NAD 2200 the right channel is internally inverted in polarity. When a bass waveform
causes the left channel to draw current from the positive supply, the right channel draws its bass power
from the negative supply, and vice-versa. This efficient usage halves the instantaneous drain on either
supply, allowing much stronger bass to be reproduced without draining the supply.

Maybe this is the problem?????

[patwhite]

the 2200 has only one big power supply and the inverted bass feature...but I do believe it's the bridging issue that requires non common grounding. I also have a Proton d1200d which is dual mono but is not bridgeable...no common ground issues in the manual. however, on my smaller protons like the d940 and the d540, both bridgeable, it says not to use with common grounds.

[F1nut]

Hoosier has hit the nail on the head!

Just because you can bridge a amp shouldn't cause any problems unless you actually bridge it and it becomes a mono block. A dual mono amp is just like using two bridged amps, in a sense it would be two mono blocks in one chassis. You can not use a dual mono amp with the SDA's unless you use the AI-1 interconnect, the same goes for mono blocks or any non-common ground amp. So, in this case it's the inverted bass feature that's the issue, not that you can bridge it to a mono block.

[patwhite]

there you have it...use the right connector and you are good to go with that 2200. (I wonder if the inverted bass issue follows thru with my proton stuff as well? Both Nad and Proton used similar technology, though when comparing the nad 2200 with the proton d1200...both very powerful, the proton is more musical and detailed..in my humble opinion.

[F1nut]

From my knowledge of the two companies, I would say yes, same issue. They are basically the same with Proton being slightly better than NAD.

[patwhite]

slightly better and "prettier". I used the 2200 years ago to power a set of '86 monitor 10b's. now those 10b's are in my basement audio room being powered by a proton d540 integrated. Still have the 2200 and need to sell it I suppose. the d1200 is in the family room hooked to an nad preamp with b and w speakers. Just ther other day, a fella from my area had an ad in the paper to sell a pair of sda/srs for 35 hundred. thought that was way too high! would be nice to have!

[F1nut]

$3500.00......he's dreaming!

[german]

It seems,that the SDS 2-B eats a lot of power.So I'm too looking for some better solution,than my old Technics 7700k.In spite of its relativ high powerconsumption of 560 Watts,it seems that it works too hard for feeding the SDA.
So I´m thinking about buying an Accuphase,or a Luxman,or,what would be cheaper, a Yamaha.What do you think?What sounds best?

[F1nut]

You have a pair of SDA 2B's also?

[german]

@F1NUt
only SDA 2-B---not also (Polk Auidios)
German not G-man

Perhaps my posting in this thread confused .But I read these other postings,and searching for an Amp fitting to the SDA ,is just my momentary doing.

[F1nut]

Oops, my fault.

Ok, are you looking for a amp or a receiver?

[german]

searching an amp,but I don´t know the maximum allowed input of the sda2-B

[F1nut]

Max. rated at 350 wpc, but you could feed them more. Out of the 3 you listed I'd look into the Accuphase. What other choices do you have in Germany and what's your price range? The recommended minimum to drive the SDA's properly is about 200 wpc, but more important is a high current rating.

BTW, 560 watts maximum of power consumption is not very much really. A amp rated at 300 to 350 wpc draws about 1800 watts maximum.

[g-man]

Ok..so the real issue here is that I need to get that interconnect cable...the AI-1 and my amp problem should in theory be solved..?..So.wher can I get that cable.? does Polk have that one for sale..?

and I got the Meridian 557 power amp and theMeridian 501 pre-amp for $2700. only demo used.A bit more that I imagined I'd use on a amp rack,but heck..it's high-end amps..!..:)

PS.

The prices you opperate with in the States.can't be compared with
the Norwegian price range..so to clearify a few things,a Big Mac large menu costs $14 here..
Imagine the costs for greate sound..:rolleyes:

G-man

[F1nut]

G-man,

I mentioned this before, but I quess you didn't understand. You can not use a dual mono amp with your speakers, nor can you use the AI-1 either. The AI-1 only works with SDA models that have the pin/blade type interconnect cable, yours has the blade/blade.

You'll either have to return the amp and get something different or find some SDA's with the pin/blade type cable.

BTW, that MickyD food will kill you.....YUCK!

[german]

Not so easy to decide,which Amp it should be. Meanwhile Accuphase is my favorit.But yesterday I saw another very interresting amp :The ASR Emitter 1 (http://www.asraudio.de/info/asr-emitter1.pdf)
What I dobn`t know,is,if Ican run it with the sda.Also a call with ASR couldn´t answer my question.
If it doesnt work,i-is the AI-1 still available?

[F1nut]

Ok, let me make this as clear as I can. You CAN NOT use the AI-1 with your SDA 1A's.

You CAN NOT use a dual mono, mono blocks or a non-common ground amp with your SDA 1A's.

[german]

NOT SDA1---- ITS a SDA2-B not blade blade

[hoosier21]

You are still out of luck, the 2B's can't be used with the AI-1 interconnect either. The manual for the AI-1 states that the AI-1 can not be used with the 2B's without crossover modifications.

Find a nice common ground amplifier and be done with it.

Good luck

[F1nut]

Damn, I've done it again! I'm sorry, but I keep confusing you with g-man and his 1A's.

According to the info that I have you can use the AI-1 with 2B's if the serial numbers are higher than 14115 for the left channel and 14124 for the right channel. However, they may require a blade/blade adaptor (I've never seen one) be used.

The AI-1 is not available from Polk, however you can make one. Here's some info on how to do it, http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=23442&highlight=AI1

As Hoosier stated, it might be easier to get a common ground amp and be done with it.

[german]

thanks for reply--
meanwhile I had a further call with ASR and had the luck to speak with the Boss ,mr. Schäfer. He told me that the ASR -Emitter
has a common ground. So as the Accuphase I like to buy and the ASR-Emitter,have both common ground,that problem is solved for me.

[F1nut]

Excellent!

[german]

So at least my decision which Amp is good enough to feed my new ( for me) SDA2-B is the Accuphase E405.I bought it yesterday. What a great changing the sda2-b with the Accuphase and to weeks ago the Technics Loudspeakers with Technics Amp.The sound changed alot.-

[BobMcG]

G-man, Congrats on owning a pair of SDA-1As. It's true, you don't have to look for an AI-1 (Polk SDA Non-Common Ground Interface). There is no application for the SDA-1s; 1As; 1Bs; or even 1Cs with serial numbers below LC 5975, RC 6001. HOWEVER some of the earlier 1Cs could use an interface but would require plug adaptors and some modification to the crossover. These would fall in the following serial number range. RC 6001 thu 6310 & 6501 thru 6678 and LC 5975 thru 6370 & 6532 thru 6656.

German, Also congrats being the owner of a pair of SDA-2Bs. If needed, and your serial numbers are the following or above, you could make use of an AI-1. LC 14115, RC 14124. HOWEVER Polk states that all SDA-2Bs require plug adaptors and some internal modification to the crossover first.

The AI-1 has been out of production for years but you could make one yourself. You could find out about doing this at this link. Check the "files" and "photo" sections. (I know I'm being a bit selfish but I do have two POLK AI-1s. One I'm using and the other is NIB. For me it's a collector's piece and not for sale.)

http://groups.yahoo.com/group/mikespolkpage2/

You might find more interesting SDA stuff here too.

BTW: For those interested in DIY projects, you can also make your SDA-1Cs bi-wireable. I don't remember if the schematic for this is on the site or not but if not it's available and has been done.