SDA SRS's and the Adcom 5802...

jcmccorm

I happily hooked up my new eBay purchase, an Adcom 5802, to my SDA SRS's and as soon as I flicked on the power to the amp, I heard a LOUD horn-like sound. I quickly turned off the power. I checked my wiring and tried it again with my hand on the switch and the same thing happened.

I switched back to the 555II amp and I think my drivers and tweets are all ok.

I searched the forum here and discovered that perhaps the 5802 is not a common ground amp, which the SRS's require. I measured the resistance between the negative speaker output terminals and it's low at 20ohms, but not common ground. Furthermore, I believe that my SRS's (blade/blade) will not work with an isolation transformer in the IC cable.

Am I screwed?

The amp was not cheap (well, less than a lot of you have probably spent on amps)

Worse, if all higher powered amps are not common ground, I'm severely limited to the amplifier upgrades I can do for me SRS's.

Please someone tell me how to make this work! Can I connect the output grounds together on the amp? (probably a good question for Adcom. Wish I had a service manual for it).

Cary

VR3

Adcom has service manuals on their website, look around...

www.adcom.com

F1nut

Most amps are common ground. Sell the Adcom and do some homework before you buy a replacement.

jcmccorm

Thanks F1nut, sounds like good advice and I've resigned myself to having to sell it. Fortunately, it's likely that I'll be able to recover most if not all of the cost (except for shipping). The Adcoms seem to hold their value well.

When you say most amps are common ground, do you also mean amps with higher output (>200W/ch)?

Assuming that it's impossible to convert the Adcom, do you have any recommendations for a nice amp costing less than $1500? Thanks!

Cary

F1nut

No, it's got nothing to do with the wpc rating, just the design. You have mono block amps (non-common ground), dual mono amps (non-common ground), regular common ground amps and then you will find a few "odd ball" amps that for whatever reason are not common ground amps. If you're ever in doubt, contact the manufacturer first before buying.

I'll work on a few ideas for you.

hoosier21

you may want to have the amp checked out. At least try it on the SRS's without the IC connected to see if it sounds ok.

jcmccorm

Thank you F1nut!

Hoosier, yes, I'm planning on putting it back in (It's a PITA though to swap out with my 555II) and trying it without the IC cable. If it works in that scenario, then there's no doubt what the problem is.

Cary

BlueMDPicker

Cary,

Did you, perhaps, change IC's at the same time as adding the new amp? I had an identical experience with my PS Audio Delta 200, the SRS's, and new Audioquest interconnects. The AQ Diamondbacks were the culprit. In combination with the rather unique power supply isolation design of the amp, the "bleed wire" in the IC design (terminated at ground on one end only) was instantaneous HORN BLOWING followed by fuse blowing in the amp.

I could take the AQ Diamondbacks out and substitute with anything else, no more problem. The AQ's work wonderfully with my Dynaco ST-70.

Mike

Edit: DarqueKnight uses that amp with the SRS 1.2's - so I don't think it's the amp.

BigJim

I bought a GFA-5800 before checking, and luckily found out (from the forum) that it was not common ground before hooking it up... I called Adcom and they stated that both the 5800 and 5802 are not common ground.. I was able to get the A1 cable from a fellow member and it works great, but I don't think it works with the blade/blade connection...

jcmccorm

Hmmm, interesting!

I'm using some pretty run-in-the-mill Acoustic Research interconnects. The same that I was using with the 555II. I'd be really surprised if they didn't ground on both ends but I'll check it. Thanks.

Cary

F1nut

Cary,

Slightly over budget, but a nice amp (much nicer than the Adcom)with plenty of power. I'm not sure if it's common ground or not, so you should check with Classe first.

http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1114739983

Under budget, but not as powerful, http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1113132298

F1nut

Nice Halo amp, http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1114861966

DarqueKnight

Originally posted by jcmccorm
I happily hooked up my new eBay purchase, an Adcom 5802, to my SDA SRS's and as soon as I flicked on the power to the amp, I heard a LOUD horn-like sound. I quickly turned off the power. I checked my wiring and tried it again with my hand on the switch and the same thing happened.

Please someone tell me how to make this work! Can I connect the output grounds together on the amp? (probably a good question for Adcom. Wish I had a service manual for it).

Cary

Cary,

The howling, horn like sound is caused by the amp seeing a short when the SDA cable is connected.

Connecting the output grounds of the left and right channels will solve the problem.

Following is an exerpt from an email response I received from Adcom in November of 2000:

"From: Scott Yeaton <syeaton@adcom.com>

There are 2 options for you to do. You can get a cable from Polk for those speakers, the AI-1 cable. This connects the 2 speakers and deals with the common ground problem. The other option is to take a piece of speaker wire and run it between the 2 negative terminals of the amplifier that you are using. This will not hurt the amp at all so dont worry about that. This a problem that has been common with the 5800, 5802, and 5500, all our newer amps and those model speakers.

Thanks and good listening

Scott"

DarqueKnight

Originally posted by BlueMDPicker


Edit: DarqueKnight uses that amp with the SRS 1.2's - so I don't think it's the amp.

When using Adcom 5000 series amps with my SDA 1B's or SDA SRS's, the negative speaker terminals must be connected.

When using Adcom 5000 series amps with my SDA 1C's, CRS +'s, or 1.2TL's, the negative speaker terminals do not have to be connected.

F1nut

Well, there ya go, no need to sell your amp.

jcmccorm

Excellent!!!!

Thank you Raife! I was hoping that I could just bridge the negative terminals together but I didn't want to try it without schematics or a note from Adcom (I shot them an email last night).

Thank you very very much! I hope to enjoy the amp this evening.

Cary

jcmccorm

But shame on you F1nut. You had me drooling over that Classe CA-300 amp last night....

Thank you for taking the time to find those for me. I've started trying to learn more about the Classe and Parasound so they're on the short list for the next upgrade cycle (which unfortunately seems to be getting quicker lately)

Cary

F1nut

LOL.......you should be drooling, I was. IMO and for the money, it's in a whole different league.

jcmccorm

That CA300 and the Parasound A21 are both beatiful to look at. I'll probably have to go to Atlanta to hear them.

Off topic for the thread, but related anyway, at what point, if ever, does improved amplifier performance get lost when using the SDA SRS's? I dearly love these speakers, but wonder if newer designs would allow me to discern improvements in amplifiers better. Keep in mind that the question is somewhat ignorant as I haven't auditioned any new speakers lately, but I'm sure a lot of SDA owners have and I'm curious how the SDA's stack against newer stuff.

My next upgrade will be the preamp. I've had my Outlaw 950 for two years and it's a great value for the money, but I think I prefer the sound of the Adcom GTP 740 that it replaced.

Cary

nadams

Around these parts, I think that the only speakers that can come close to the SDA's are the Lsi series, but even then, you don't have the SDA effect. SDA's are unique, and they are still high-end. They probably always will be (unless Polk brings back the SDA's, like they did the Monitor series :P).

Enjoy what you've got!

And, I think that the more power these speakers have available to them, the better. But... quality power can be more beneficial than gobs of low-quality crappy power

BlueMDPicker

Originally posted by jcmccorm
Off topic for the thread, but related anyway, at what point, if ever, does improved amplifier performance get lost when using the SDA SRS's?

Cary,

Did you do the Xover upgrades yet?

F1nut

That's a very good question and one which I hope some others chime in about. IMO, the SDA's are still top notch performers not easily bested by much out there today. With the new style tweeters installed they are even better and overall are a well rounded speaker.

Just a suggestion since you seem to be interested in improving your gear, check out tube pre amps. It's the opinion of many including myself that a tube pre amp mated with a good SS amp really brings out the best of both worlds.

jcmccorm

Part Connection had backordered two of the resistors and they just came in yesterday so I'll be doing that this weekend (and referring back to your's and Raife's threads on the subject!)

I've already replaced the tweeters and will do the crossovers this weekend so I definitely want to hang on to these speakers. I'm just wondering what else is out there....

Cary

BlueMDPicker

A world of great things. There have been some great posts lately (one by George Grand sticks in my mind) about various speaker strengths and weaknesses. F1, Doro, Russ, Sid, Zero, Early and many others regularly post excellent remarks on various speaker designs.

I'm almost certain you will have a new found amazement in your SRS's when you do the upgrade. They can hold their own with a ported bass design and horn loaded tweeters with the better Xover components (using my component lineup) - and that's where they were "lacking" IMO with my equipment.

IMO, it boils down to the sound you're after. And, only you will know it when you hear it.

DarqueKnight

Originally posted by jcmccorm
Off topic for the thread, but related anyway, at what point, if ever, does improved amplifier performance get lost when using the SDA SRS's? I dearly love these speakers, but wonder if newer designs would allow me to discern improvements in amplifiers better. .......I'm curious how the SDA's stack against newer stuff.

I used to have the same curiosity. I spent an afternoon at Dunlavy Audio Labs auditioning their highly regarded speakers, one of which was a model that cost $32,000/pair. I posted a comparison of my listening impressions of the differences between the Dunlavy SC 4 and the SDA 1C back in January of 2001. I was not impressed with any of the Dunlavys to the point of wanting to own them, although I thought they were great speakers.

For the type of music I prefer (acoustic jazz) I have not been able to find a more accurate and sonically satisfying speaker. When I say accurate, I mean the reproduction of the natural sound of what I hear during a live performance.

The point of diminishing returns is reached much more quickly with source material than with amplifiers.

TroyD

I'd say that over the years that there are some speakers that have consistently performed well beyond their price point and have, as a result, culitvated quite a following: Vandersteen's, AR-9's, Carver Amazings, SDA's, Dahlquist DQ-10's, Maggies...to name a few. One of the benefits to these types of speakers, IMO, is that they aren't constricted to a certain level of gear. Whatever level your electronics are at, they will give you the performance you expect.

Just the way I look at it.

BDT

Tour2ma

Originally posted by jcmccorm
Off topic for the thread, but related anyway, at what point, if ever, does improved amplifier performance get lost when using the SDA SRS's? I dearly love these speakers, but wonder if newer designs would allow me to discern improvements in amplifiers better. Keep in mind that the question is somewhat ignorant as I haven't auditioned any new speakers lately, but I'm sure a lot of SDA owners have and I'm curious how the SDA's stack against newer stuff. Cary

Cary, it's your thread so you're allowed to take it wherever you want to...

I never really have thought about searching for a speaker that let's me hear amps. I'm more along the lines of looking for amps that bring out all a given speaker has to offer. Once the need for clean power/ high current are satisfied, it seems the amplifier search is for synergy. Some amps just "fit" the SRS's better, and price is not a determining factor.

As for other speakers (be they new or old) vs. the SRS's and other SDA's, I think it pretty much depends on what music you are listening to and what you value in the reproduction of that music, e.g., depth of soundstage vs. width, pinpoint placement of instruments, etc.

SDA's do some things great, and many things well. Other speakers can be great in an area where the SDA's just do a good job.

But bottom line... in over 15 years nothing has nudged my SRS's from the top of my pyramid.

jcmccorm

Hey guys, thanks for sharing your experience in this thread.

Just to complete the original topic, for the benefit of any future Polkies in the same situation, bridging the grounds of the 5802 works like a champ.

The 5802 replaces two 555II's that were horizontally bi-amping the SDA SRS's.

After bridging the ground, I replaced the "bottom" (supplied the low frequency terminals) 555II with te 5802. The first thing I noticed was that the imaging was "wierd". No better way to describe it. I listened to several 2 channel recordings and although I have not ever claimed to have golden ears, the imaging difference was obvious. Some stuff was focused in the center, some stuff was spread out to the individual speakers (it sounded like the instruments were coming right from the speakers, not spread out further via SDA or in between). There was very little information spaced between the center and the individual left and right speakers.

I popped in Avia and checked phase and also checked my connections. It was all good.

Without a line-level crossover, biamping probably has dubious benefits anyway, so I got rid of the other 555II (supplying the high frequency terminals) and just bi-wired the 5802 to the SDA SRS's. At 300W/ch and the levels I typically listen at, I don't think I need to worry about running out of headroom in the amp.

Now it was right. Once again, I've never considered myself able to discern differences that someone with more audio listening experience might, but the imaging difference was very obvious to me. Much more focused and tighter placement within the soundfield. Nothing against the 555II's because they've been faithfull beasts for years, but the 5802 improved the stereo imaging.

As for other aspects, they are much more subtle. As several members have mentioned to me on this forum, the MOSFET design of the 5802 is smoother than the bipolar 555II. It's not that obvious however and I had to pick certain tracks where I knew I'd experienced some "edgyness" (for lack of a better term). The difference is noticable, but only slightly.

I like to listen to movies and music a little loud, but way below ear-splitting. Therefore I don't think I'm reaping big benefits from the extra power. One scene in a movie features a toilet being thrown through a large window. The crash is loud and there's lots of little pieces of glass hitting the floor. After the very initial "attack" of the sound you can hear individual pieces of glass tinkling within the wall of sound. My aural memory isn't that good (better to do a quick A-B comparison) but the 5802 might be a little more detailed with this sound. If it is, it's very subtle though compared to the 555II.

Anyway, the 5802 works great with the SDA SRS's if you short the output grounds together.

The quest for audio nirvana continues. Next stop is the pre/pro....

Cary

Tour2ma

Cary,

Does sound like an absolute phasing issue when you were bi-amping.

When you ran the AVIA, did you phase check the HF and LF drivers individually, i.e., disconnecting one and then the other?

Just thinking the test tone(s) may have been in one of the FR's and led you to believe all was in phase...

Glad to read you're able to pair the Adcom with the SDA's...

engtaz

What did you do with 555's?

engtaz

engtaz

No, you still connect the speakers the normal way but you also have a jumper connecting both speaker grounds on the back of the amp.

engtaz

What did you do with retired CRS+???