New amp

motorstereo
motorstereo Posts: 2,146
edited November 2006 in Vintage Speakers
Hi I have a pair of polk sda 2.3's which I love. I was running them with an adcom gfa 555 ll like quite a few folk do with their sda's. At first the adcom sounded wonderful but almost unnoticably the sound decayed over the past few months. No real nice sparkling highs, the sda effect was there but it wasn't as pronounced and the bass didn't have the slam it used to. I was also starting to listen to them less and less as it just wasn't enjoyable anymore. I changed out to an older bose 1800 and everything is back in full force. Sounds coming from everywhere, huge soundstage and wonderful highs. I wonder what happened? I checked the bridging switch on the back of the adcom and it was in the right place. The bose and adcom have similar power ratings and the only real big difference is in the damping factor; bose 40; adcom 800. I would think the higher damping factor on the adcom would be an advantage because of all the drivers involved. All I know is now I'm happier than ever with these speakers. Any thoughts anyone on why the adcom would "get tired"? Maybe the sda effect is tough duty on amp? I'm at a loss why a so-so amp should make these guys sing once again. An adcom getting beat up by a bose; oh the horror; but it's true. Now I'm wondering what an even better amp will sound like on the 2.3's. Thanks; Brian
Post edited by motorstereo on
· Share on FacebookShare on Twitter

Comments

  • F1nut
    F1nut Posts: 50,729
    edited November 2006
    Obviously your Adcom amp has a problem. Send in for service.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

    · Share on FacebookShare on Twitter
  • hearingimpared
    hearingimpared Posts: 21,136
    edited November 2006
    F1nut wrote:
    Obviously your Adcom amp has a problem. Send in for service.
    That is blatantly obvious. If you swapped the amp out with a crappy amp and it sounds good. . .the Adcom has a problem. . . basic troubleshooting 101:eek:
    · Share on FacebookShare on Twitter
  • DarqueKnight
    DarqueKnight Posts: 6,765
    edited November 2006
    motorstereo wrote:
    Any thoughts anyone on why the adcom would "get tired"?

    Let's see....

    1. Age maybe? GFA-555 Mk II's were made from 1991 to 1997. That means your amp is between 9 to 15 years old. Components (especially electrolytic capacitors) can change value and lose performance over time.

    2. Prior abuse maybe? Most folks acquire these on the used market where they are the second, third, or more owner. If you are not the original owner, there's no telling what kind of secrets your 555 Mk II is hiding.

    Taking the amp in for service was good advice. Good luck.
    Proud and loyal citizen of the Digital Domain and Solid State Country!
    · Share on FacebookShare on Twitter
  • motorstereo
    motorstereo Posts: 2,146
    edited November 2006
    I wouldn't call the bose "a crappy amp". But it's specs would suggest the adcom should sound better than the bose. "9 to 15 yrs old" hell that's like brand new to me. The ol bose is from 1973. The adcom is one of my newer pieces and I think I'll unload it as opposed to getting it updated. I had mentioned a while back that I was also running a pair of sp3500's on top of my 2.3's with tube monoblocks. I was ridiculed by some here but I was adamant that it sounded nice. I can't imagine now muddying up the sda sound with those sp3500's. I think I'm hearing the sda effect with all it has to offer for the first time and I'm very impressed. I honestly don't remember the adcom sounding this good even when I hooked it up for the first time. This old bose made a heck of difference almost like hitting a mono switch to the stereo position. Yup I think I'll retire the adcom.
    · Share on FacebookShare on Twitter
  • nadams
    nadams Posts: 5,877
    edited November 2006
    Make sure you're getting output on all channels of the Adcom. It's possible that one of your channels is dead, but with the SDA cable plugged in, you would still be getting some sound from both speakers. The GFA-555 is a fine amp... hell, I'm running an 80's GFA-535 on my SDA 2's and it's more than I could ask for with these speakers. That 555 deserves some respect...
    Ludicrous gibs!
    · Share on FacebookShare on Twitter
  • George Grand
    George Grand Posts: 12,258
    edited November 2006
    Those Bose 1800's are in fact pretty nice amps.
    · Share on FacebookShare on Twitter
  • hearingimpared
    hearingimpared Posts: 21,136
    edited November 2006
    motorstereo wrote:
    I wouldn't call the bose "a crappy amp".

    Sorry, poor choice of words.:o :D
    · Share on FacebookShare on Twitter
  • george daniel
    george daniel Posts: 12,096
    edited November 2006
    Did you check the fuses?
    JC approves....he told me so. (F-1 nut)
    · Share on FacebookShare on Twitter
  • motorstereo
    motorstereo Posts: 2,146
    edited November 2006
    Yup I checked and double checked all my connections on the adcom. I unplugged and replugged the sda cable and it did make a difference so I know that was working. Both channels are working and the amp has seen almost no abuse. Now the bose is very beat up looking. All the functions work but it looks like it toured with the rolling stones. I also thought the gfa555ll would be an excellent amp with the 2.3's. I'm not bashing the adcom by any means but I'm also not about to put it back in service with the polks ever again either. I still can't help but feel that the high damping factor on the adcom has something to do with the sterile lifeless sound. Glad to hear others are happy with their adcoms but me I'll just stick with my old beat up looking, war wagon bose. I was thinking I may have had a bad adcom amp but I actually have 2 of them. I tried running them bridged as a pair; lots of power but really a very poor quality sound. I also tried running one against the other and they both sounded similar. Could it be that I had 2 lemons? Yes I suppose I could be that lucky but it's highly unlikely. Looks as though my adcoms will be serving duty as paperweights for now.
    · Share on FacebookShare on Twitter
  • motorstereo
    motorstereo Posts: 2,146
    edited November 2006
    george daniel wrote:
    Did you check the fuses?
    Yes I did. They're all brand new ceramic fuses. Don't know if that made a difference or not changing them out but they're all good and all of the same value.
    · Share on FacebookShare on Twitter
  • motorstereo
    motorstereo Posts: 2,146
    edited November 2006
    Do believe I've discovered the problem. Just like a few members here suggested it appears that I have a lackluster adcom. Thinking back when I first got these polks back in March I was taken aback by their great sound with an adcom gfa 555ll. Couldn't leave well enough alone I had to try bi-amping them with the adcom for the bottoms and a proton d1200 for the tweets. Ended up touching both speaker outputs of both amps together while they were running for a milisecond and fryed both amps. I know it was a real dumbass move but I seem to excell at making those stupid human tricks. Anyway I put the other adcom gfa 555ll that I had into service right away and did notice the sound seemed to be a little off. Course I figured it had something to do with the stupid human trick. Didn't think to much more of the poor sound quality other than I planned on recapping the speaks. Seems as though now looking back I had one really good adcom and one that wasn't and still isn't so good. At least that's my interpetation of the problem and it probably isn't in the damping factor difference. I had a bud over this weekend and he remembered the 1st adcom sounding wonderful. I also tried to think back as auditory memory is so short but I had to agree that before the stupid human trick the adcom and the polks did sound great. I do know that I'm almost obscenely happy with the old bose driving the 2.3's now. Hey live and learn but I'm glad I did finally get to the root of the problem. Now to get those adcoms and the proton fixed. Lesson learned the hard way; always make connections with the equipment turned off.
    · Share on FacebookShare on Twitter