Bi-amplification or Bridged mode for SDA SRS

zagloba

I am assuming that the new current induced is an exact replica of the old. I am guessing that no differences in impedance would be inherant in this exchange.

I believe Polk knew this as fundamental but who has done this in this forum?

There is probably information already listed but there is a massive amount out there. I want to insure transparancy of electrical information and specifically sound.

I would like all three models. The SDA SRS's that I covet now as well as the 1.2 and 1.2TL's. It would be my pleasure in the future to know and hear the difference to influence Mr. Polk to resurrect a meaningful technology.

I choose this technology and the sound for a good reason like the rest of you. It is simply stunning. I chose this route independant of cost but rather for clarity of sound and a real experience of pleasure.

Who has played with bridged vs. bi-amping?

This maps to my original question and my involvement here.

John

Tour2ma

John,

Here's a current thread on a fellow member's efforts to build an AI-1:
http://clubpolk.polkaudio.com/forum/showthread.php?s=&postid=238651#post238651

The signal the transformer induces to be passed on has no choice but to be replicated. You will note in reading the thread that signal strength is a variable that makes choosing the right transformer essential.

I am not sure what "fundamental" you are referring to in your question.

As for bridged vs bi-amp... a number of members have played with both. George Grand is one solidly in the bridged camp for driving his Carver Amazings. I agree with him for the CA's. For other speakers, I've found the two to be indistinguishable.

zagloba

By "fundamental" I meant that polk would not offer this solution without understanding and designing a solution that did not change the sound. Your indication is that of a "transformer".

I need more.

I will read the thread and go from there.

Thank you.

I will post my results.

And yet,

Can someone please comment on their own personal experience related to what I am attempting? And my initial question and the origin of this thread?

John Capik

zagloba

I spoke with Ken at Polk today. He was great and confirmed everything you folks were telling me. He will send the Polyswitches out on Monday and maybe throw in a schematic.

Ken confirmed I could not run these speakers in bridged mode. And sadly, the transformer solution is not available with my SDA SRS model. The pin/blade vs blade/blade, was adopted to allow bridged mode and therefore crossovers were heavily modofied to accomidate this.

Ken did not know how I got away with trying a bridged configuration and I was almost ashamed to tell him I had. He had no explanation as to why. I believe it may be the procetive circuits in the Mac that allowed this questionable behavior at all.

I asked Ken to post his thought here as well.

Thank all of you very much. I feel a bit initiated to the goodness of this club. I will try to reciprocate sound information in the future.

John

F1nut

Originally posted by zagloba
II believe it may be the procetive circuits in the Mac that allowed this questionable behavior at all.

That seems like the most reasonable explanation. To get more power you could get a pair of mono blocks, then connect the negative posts together creating a common ground. That will allow you to use them with the SDA's.

Hope you stick around and have a Happy Thanksgiving.

Tour2ma

Now John knows to never, ever doubt our sage advice... that is until we're obviously wrong...

John,
Look at it this way... now you have full justification for your pursuit of the 1.2's.

And don't worry, we'll come up with something for the 1.2tl's as well...

Happy Holiday...

zagloba

Folks,

I just received my second McIntosh MC300 and realized these amps may also run in "mono parallel" mode. This takes the output down to between 4 and 8 ohms but the amps are capable of 1 ohm loads at full output(600 watts). I thought these speakers were about 5 ohms?

Both the - sides (common) are connected together as are the L and R +(positive) sides.

So even though the SDA SRS versions cannot use the interconnect transformer(confirmed by Polk), for bridged operation, I believe the mono parallel configuration should work without flames?

I still have a common ground and therefore?

What do you folks think. I hope I get a quick reply as I am panting to connect.

John

Tour2ma

z,

I have no idea what "mono parallel" means. I can't read anything into what you wrote that says "common ground established".

If you are running two separate amps, be they mono-blocks or bridged, and cannot create a common ground configuration by wiring each amp's negative speaker terminals together, you are endangering them, if you wire them to the SRS's.

I can only advise you to consult McIntosh and look in over at www.AudioKarma.org. AK is a great vintage forum with a whole section for McIntosh. There are a few posters over there that really know their Mac's...

The SRS's are nominal 5-ohm impedance speakers.

B3Nut

MC300's have autoformer-coupled outputs, and they do have the option of conventional bridging or paralleled-mono operation, similar to "strappable" tube amplifiers. One of the nifty features of the autoformer-output Mc amps.

TP

zagloba

Thanks for the responses. I hooked things up and all works. I am attaching the specs from McIntosh(several scans).

I was not that impressed with the response of 600 watts vs. 300 watts per side. But I believe there is a common ground. I want to compare a bi-amp configuration for output and sound quality. I do not expect much difference. I would just like the crossover network to distribute power to drivers rather than amps dissipating power.

I mentioned before that I was confused when I attempted bi-amping. 300 watts to the high end? Ken told me the crossover fq was 2000 hz. Could the high end consume 300 watts? With two amplifiers running this way, I was confused

The single Mac is impressive enough. But like all of us(I should speak for myself), I looked for more. The sound is stunning.

I have ventured deaply into SACD and DSD discs.

I will contact McIntosh today.

I may need to call Polk(Ken) as well as I have not yet received my polyswitches. And there is an issue with the crossover network regarding the distribution of power.

z

zagloba

second scan re McIntosh