Adcom GFA-5503 common ground amp?

stoogefan00

Just bought a set of SDA-SRS that are in excellent cond. The gentlemen I purchased these from said they were the 1.2's but after delivery I noticed 13 screws in the crossover plate in front and a blade- blade connection leading me to believe I have SDA-SRS 4 ohm speakers. My question is my Adcom amp is a GFA-5503 is this amp common ground or non common ground and if it is non common ground can I run a piece of speaker wire to both neg. terminals? I checked past discussions on this but seem to find conflicting answers I'm hoping someone can help as I am a little excited to try my speakers out but at the same time I don't want to wreck them or the amp for that matter. Thank you for any time you can give me in regards to this matter.

gudnoyez

It is not a common ground amp I have 3 Adcoms & the 5503 is the one of the three that is not a common ground. I have heard you can strap the terminals but not sure if I would recommend it.

gudnoyez

http://www.users.interport.net/a/d/adcom/manuals/gfa5503.html

The 5503 is a Mosfet amp they are not common ground you could find out and strap your terminals and try it out, but like I say I would not recommend it.

F1nut

Strapping, if possible, affects the sound quality in a negative way.

ZLTFUL

@gudnoyez has my old GFA-5503 and I can tell you 100% without a doubt that, from the factory, the Adcom GFA-5503 is *not* a common ground amp.

The only way that you are going to be able to 100% verify that is to get a multimeter and check the resistance between the speaker ground terminals. If it reads 0 or just a hair above 0, you have either strapped grounds or the only 5503 to ever come out of the factory with a common ground.

I would also suggest building a dreadnought over strapping the grounds. It isolates, which will prevent the magical blue smoke. And it sounds WAY better than strapping the grounds.

boston1450

GFA-555 was a sweet match for my 2b's with a 565pre.

gudnoyez

Go on E-Bay I bet there are a few Adcom GFA- 555's or GFA- 555II ' s those would be the ones to get, I have read a few negative reviews on the new Adcoms.

stoogefan00

This seems strange it seems to me some time ago I had called Adcom and talked to a rep about this and he stated after looking the specs on my amp that it was common ground this coming right from Adcom. I called him because at the time I was going to buy a set of SDA2A speakers and needed clarification but that purchase did not work out. You say you would not recommend strapping neg terminals what is my other options at this point? other than buying another amp. Also could I take an ohm meter to each of the neg terminals to check continuity to see what if any reading i am getting to also help confirm common or non common ground?

stoogefan00

Thank you sir I will give that a try.

gudnoyez

Why second guess you obviously have your doubts but won't accept the adcoms reps answer nor mine. I have 3 pairs of SDA'S and they will only be hooked up to my 555II or my 545II the 5503 is used for my non SDA'S as it is not a common ground amp. I can say that 3 channel 5503 does an excellent job running my fronts and center channel nice amp plenty of power.

stoogefan00

Thanks gudnoyez not second guessing its just when you have a high end audio lab tech and an Adcom rep along with numerous others telling you to use the 5503 because its common ground and yet others state its not I just need to know because I don't want to wreck my speakers or my amp what exactly could happen if I strap my terminals that you say you would not recommend? Why would you not recommend this is what I'm asking?

gudnoyez

Strapping your terminals with speaker wire just don't sound like a good idea perhaps a solid pair of jumpers would be better.

stoogefan00

I understand and thank you gudnoyez

stoogefan00

Thanks guys, sounds like a new amp is in order. What model Adcom amp would you recommend that would be common ground. I would like to stay with Adcom I've kinda grown to like them over the years having several models in the past. Once all this is ironed out I will post pics, right now very happy with the speakers I'm sure I'll be happier once I send them a signal.

stoogefan00

Thanks boston1450. I was just on Adcoms sight and was looking at the GFA555SE wondering if this was a common ground amp, if so might be one to consider, what do you guys think?

stoogefan00

Also found Emotiva XPA-2 power amp that might fit the bill if it is common ground. Either Adcom GFA555SE or Emotiva, which one?

stoogefan00

I'll check E-bay out Thanks

GlennDog

I would stick with the 5503 and spring for a tyranny / Dreadnaught. IMHO, you already have the better amp, as I've had the 555II & the 5503 for years. ymmv

stoogefan00

Thank you GlennDog sorry I'm not quite sure what a tyranny/Dreadnaught is, do I have to make this or can I buy one. I love these SDA'S but all this is new to me when it comes to making this amp work. If I can buy one I would do that for sure. Thanks

ZLTFUL

The Dreadnought (Glenn meant Tranny) is an isolation transformer that is added to the SDA connection between the speakers.
It does exactly as it sounds...isolates one speaker from the other...so the ground becomes a moot point.
You can buy them already built as they show up from time to time but you can also build them as the wiring diagram, suggested parts and pictures exist all over this site.

stoogefan00

I understand, I'll do some research and see what I can find everyone has been so helpful thanks ZLTFUL and to everyone else here trying to help me resolve this matter.

GlennDog

stooge, where are you located?

stoogefan00

Illinois

leftwinger57

I have about 6 sets of speakers in my 18'x15' living room w/my 2Bs front and center w/an equilateral triangle from my couch which is 9' from the speakers. All other sets are over on the side and do work well for the room and available space. I usually never gof on or comment on someone's listening space but dude your borderline hoarder(no you are hoarding and I'm guessing you do not hear them all). Sell the ones these guys want, you'll have the cash to get the correct amp amp and as F-NUT says that still might not be enough room for
those to breathe.

Schurkey

C'mon, guys.

The original poster seems to have ORIGINAL BLADE/BLADE SDA-SRS. He CANNOT use an isolation transformer. Therefore, no dreadnaught.

Testing for continuity is NOT the same as testing for resistance. A mere 20 ohms (the result of two ten-ohm resistors) between the negative terminals of my Aragon made my 1Bs unlistenable. I was lucky, no harm done to the amp or speakers...but I lost out on considerable enjoyment until I got around to strapping the negative terminals.

The Adcom 5503 in question is similar to my Aragon in that it is a common-ground amp EXCEPT for a pair of resistors which must be bypassed to use with blade/blade SDA speakers. The original poster can buy or fabricate an eight-inch jumper wire to connect the negative terminals of the amp, and he'll be JUST FINE. Those who say it affects the sound quality in a negative way has never tried to do WITHOUT the strapping on an amp/speaker combination that requires it.

Aside from replacing the speakers, replacing the amp, or going inside the amp to do "solder surgery" to bypass the resistors, strapping is the ONLY OPTION. It is simple, dirt-cheap, and instantly "reverseable" by merely yanking the wire out of the negative binding posts. There's essentially no down-side.

GlennDog

Oops! Missed that B/B part . . . sorry

stoogefan00

Just got off the phone to Emotiva and ordered a XPA2 today should be here Thurs. so I have to wait a few more days to get my SDA SRS up and running. I guess getting these speakers was more reason to purchase a new amp and take all guess work out of the common ground problem. I did take a multi tester to both neg terminals and sure enough non common ground amp. So thanks to all for helping diagnose this problem, now I just need to find a new home for my GFA5503 and GFA5300 amps to help offset the cost of the new amp.

Schurkey

Sell the Communist emotiva, keep the Adcom, and put a five-dollar jumper wire between the Adcom's negative terminals. You could be enjoying those SRS speakers in an hour, and not contributing to the trade imbalance with the most hateful nation on Earth. (Less time than that, if you have some 16-gauge or heavier wire loitering around your home. You could scrape the paint off of the ends of a section of coat-hanger wire and be OK in the short-term.

ZLTFUL

I didn't know Emotiva was made in Iran and North Korea...learn something new every day.

F1nut

Ah, the lure of a cheap amp.

Nightfall

Schurkey wrote: »

...and not contributing to the trade imbalance with the most hateful nation on Earth.

I agree with you but it is nearly impossible to not buy anything from China.

OP for $200 less (which leaves room for shipping) you could have had this:

http://denver.craigslist.org/ele/4914352928.html