3 quick ?'s about SDA-1

[gkouvaras]

Hello everybody... I was wondering:

1. It says to hook up these speakers to common ground amps only. How can I tell if an amp is common ground without calling the manufactures? Are most amps common ground?

2. Has anyone every replaced the PR with a woofer or a sub? If so, which ones are reccommended and could I possibly damage the mid's or woofers currently in place by doing this? I know better than to hook it up to the crossover inside the speaker.

3. Can anyone reccomend a "vintage" amp to drive these speakers? I have been looking at the crown psa-2. But noone knows about the common ground issue on these older amps.

Thanks,
Greg

[VR3]

Do not replace the PR with a subwoofer.

The midbasses inside your SDAs are made to work with the PR, the midbasses move, the PR moves - they are like one ;)

[gkouvaras]

Thats what I thought... But I saw some 1.2's on ebay with the PR replaced with subs and the guy said it was great... I figured i'd ask the experts...

[VR3]

Yeah we made fun of that guy for a couple of weeks too ;)

[gkouvaras]

So since that issue is dead... What about the common ground thing?

[VR3]

I'm not sure how you 'check' that...

But you can call the manufactuer and they will/should know...

Ken at polk CS might have a method to check it or someone here might know, maybe do a search?

[Tour2ma]

Welcome, gkouvaras...

Yes, most amps out there are common ground. Many non-common ground amps are dual mono designs with twin power transfomers and maybe even two power cords.

Easy check is to take a resistance reading between your amp's two negative speaker terminals/ posts. If the resistance is 0, then common ground it be. If the resistance is >0, non-common.

In vintage models, Carvers are common ground amps as are Adcom and many more. Can't comment specifically on the Crown.

Which SDA 1's do you own?

[gkouvaras]

Thanks for the info... I don't know exactly which model they are... But I think they are the originals... the serial number on the right one is: RSDA2179... I didn't check the left one...
also... what exactly are these speakers rated at... I heard they could handle 500 watts... if so I think I am going to try to get a 500 watt amp... please let me know...
Thanks,
Greg

[F1nut]

Post a pic and/or describe the tweeters and drivers including how many of each. Also, does the interconnect cable have two spades or a pin and a spade at each end?

BTW, just because a speaker may be rated to handle 500 wpc doesn't mean you need a amp rated the same. Something around 200 wpc with high current will do the job nicely.

[Tour2ma]

... and, of course, it does not mean you are limited to 500... :D...

Seriously F1 is right, at some point added watts become superfluous ($0.50 word of the day) and peak to peak current capability rules the day (as in amperes). Many relatively "low power" amps, i.e., less that 200 wpc, have gobs of current in reserve, e.g., 40 amperes or more.

Also as F1 said, the first ID question is, "are the two tweeters each of your 1's have next to each other horizontally?"
If the answer is "yes", then they are the original 1's. If the answer is "no, they are arranged vertically", more questions to come...

[gkouvaras]

The interconnect cable has 2 pins and the tweeters are arranged horizontally above the 4 woofers...
The only reason I would get a 500 watt amp is because older used amps are so much cheaper than anything new... for example the crown psa-2 is 460 x 2 into 4 ohms with a THD 0.002%... I see them go on ebay all the time for around $300... anything like that new will cost well over $1000...

[gkouvaras]

also... I am currently using my Denon 3805 120 wpc to power the sda 1's. Is it really worth upgrading to a seperate amp?

[Tour2ma]

gkouvaras,

Probably, but there's only one way to find out...

If you have a friend with a 2 ch amp in the 100 wpc or more range, invite him and his amp over for a beer and try bi-amping with your Denon.

If not, shop the used market wisely and the most you will likely be out $$$-wise is shipping. Old Crowns are nice to be sure, but if you try a lesser Carver, e.g., M-400 or M-200, you'll get a test for $200 or less... and they're lighter, so shipping won't run you as much.

[gkouvaras]

Well I just won a Crown PSA-2 on ebay for $250 and I am going to pick it up to save on the S/H... I'll let you know how it works out...
Thanks for all the help.

[gkouvaras]

Well just to let everybody know... The PSA-2 is a kick ass amp... I recomend it to anyone who has a pair of SDA-1's or higher...

[Tour2ma]

Sweet... can you post a pic or two? (We love that stuff)

Rock on...

[gkouvaras]

I'll post some pics when I get back from vacation on monday... I hate getting new toys and not being able to play with them for a few days...

[gkouvaras]

Here is a pic of the amp... I just posted my system on the System Showcase... go and check it out... let me know what you think...

[gmorris]

Very cool showcase, good pics.

You say you live in an apartment? Your neighbors must hate you.;)

[gkouvaras]

amazingly they have never said anything... buy my old neighbors called the cops at least once a month... actually I built a sub a few years ago but I cannot use it because it vibrated one of my old neighbors vases off the shelf and it broke...