SDA SRS 1.2tls Best way to drive them

polkrt3000p

I have been running an Adcom 555II on the lows, and the Adcom 545II the highs biamped. I do have the option to run another Adcom 555II for the highs and run the Adcom 545 on the ceiling speakers instead of the 555. Would I gain much by switching the amps out, since they are only running the highs. Or should I do something else like Mono Bridge the 555s but risk running to hot or having the sound quality drop, plus I think there are issues trying to run mono with the 1.2tls. I do have the mono connnector cord that I can connect both speakers together for Mono. Just some thoughts when I rewire my HT rig.

Bottom line, is it worth switching out the 545 for the highs for a 555. It almost seems like overkill on the high end. I think it is just the tweeters that are being driven and I would think the 545 should run those pretty easy, but I could be wrong. Just trying to get the most out of the 1.2tls.

Oh yeah, I am running some very heavy duty speaker wire, similiar to the Monster Z series, if that matters.

Thanks,

F1nut

I do have the mono connnector cord that I can connect both speakers together for Mono.

Huh?

nspindel

If you want to run mono blocks you're much better off building yourself a dreadnought, the sound quality will be much better than the AI-1 cable that you have there. I'm in the middle of putting together a group buy for the transformer to build it:

http://www.polkaudio.com/forums/showthread.php?134643-Group-buy-Avel-Lindberg-1000VA-isolation-transformers-for-DreadNought

From there you'd need a case to mount it in (toolfan66 is the man to talk to there) some speaker binding posts, and some speaker cable.

polkrt3000p

The 1.2tls came with two cords one that is just a AI-1 and another that has the AI-1 connected to a Mono transformer of some kind, it almost looks like a power brick. About 3 inch long, not sure if it was common to get, but does say Polk Audio on it.

nooshinjohn

SDA SRS 1.2tls Best way to drive them

... to my place?

In the back of a well padded large SUV or pick-up truck.

F1nut

Ok, the straight cable is simply called the SDA interconnect cable, nothing AI-1 about it. The cable with the isolation transformer is the AI-1 and has to be used with non-common ground, mono block and dual mono amps. It does not make the speakers play in mono. Did you not get the owner's manual?

polkrt3000p

I don't think I have a owners manual on them. But back to the question at hand. 545 or 555 on the highs. Would it make that much difference or would my 555 be better used somewhere else. Just looking at what I have on hand that would not cost me anything to change out.

nspindel

Are you using either one of those cables right now? I can't give you any advice on those amps, but I can tell you that unless you're using the interconnect, you're not hearing the SDA. If you're using those Adcom amps, you should use the one without the transformer in the middle, the one with the transformer is the AI-1. It should make a very big difference. As for the Adcoms I'll let others chime in.

polkrt3000p

I am using the interconnect without the transformer in the middle.

parnold

no transformer = running with common ground amps

Phasewolf

I would set the gfa-555 to mono and use one per speaker and have it drive both the high and low and not worry about biamping and see how it sounds.

polkrt3000p

If I put the GFA-555s in Mono- would I need to use the tranfomer cable Ai-1 with the transformer or just the basic interconnect cable without the transformer. I would guess without the transformer. Has anyone tried it in mono the 555s that would be 600 watt per speaker with two 555s?

Phasewolf

I am not sure if you need to use the Al-1 but to be safe until you are told otherwise yes use it.

motorstereo

I ran a pair of 555's strapped on my 2.3s years ago. Egads of power at 800 wpc but the sound was less than stellar on those bridged adcoms. I went back to running them in stereo even though it was only 200 wpc but the sound quality was so much better.

pitdogg2

also some amps do not like the 4ohm load bridged.

nspindel

Funny you say that. I was going to chime in, but then I stopped myself. I try hard not to comment about things that I don't have personal experience with. But every review I've ever read about any bridgeable amp has been that the sound quality is not good in bridged mode, regardless of manufacturer. If you want monoblocks, do it right.

nspindel

And build a Dreadnought!

With a transformer from my group buy :biggrin:

Mr. Bubbles

I run mine on a 555II. I personally find them slightly mid heavy already and would definitely not put less power (545II) on the highs. The tweeter circuit/s are already attenuated internally with the factory crossover design so as to balance well with the mids. If you run the amps as you describe you have them now their would most certainly be an imbalance to the frequency response. You will hear very little difference (if any) in bi-amping these speakers without an electronic crossover. I would run them on a single 555II unless you just happen to have an extra 555II that would see no use unless using it to bi-amp these with a second 555II. Using 555II's to bi-amp these and having the same model amp running on the mids as you have on the highs will keep the tonal balance as it was designed. Though again bi-amping will offer little to no benefit without electronic crossovers, Even with electronic crossovers, the internal crossover would need to be modified in order to keep crossover slopes as designed originally for the speakers. I say stick with one 555II unless the other is sitting around collecting dust, then use 2 555II's to bi-amp.
Just my 2 cents.

Holy crap I just read what I wrote above. I can tell the Soma's are working. To tired to re-write. Sorry for the crazy rambling, but I think you can get my point.

polkrt3000p

So what I am hearing is having the 555 on the low end the 545 on the high end is not a good idea. I would be better off either running one 555 or biamp with two 555's (but with a minor difference in sound if any). I use to run the two mono blocks 565s on the 1.2tls. But I was getting a hum noise on the 565s and I moved them to the RT3000s and then no hum noise. Even with the A1-1 transfomer inline to protect the mono blocks. But maybe I have to look at doing that again. I have had the amps checked out and replaced the caps, but still got a low frequency hum with the 1.2tls. Therefore i switched and had the 555 and the 545 run the 1.2tls. I just think that 200w stereo is not enough power for the monster speakers therefore I tried to biamp them. I do have an extra 555 that I can switch out that is running the ceiling speakers to run the high end, just thought it maybe overkill or not notice a vast improvement. But I am open to options and this forum is the best when doing some tweeks. Any other ideas are welcome.

Mr. Bubbles

build a dreadnaught, use the 565's on a dedicated single outlet and be sure your source and pre are on the same circuit as the amps and use high quality interconnects and/ or take very good care to isolate ground loops. But without spending any extra money over what you already have, run the 2 555II's in bi-amp mode.

nspindel

The thing is, I remember when I first moved from using the stock sda cable to even a custom run of speaker wire, the speakers just opened up so much more. A better sda connection did wonders for me, albeit smaller speakers.