Carver amp help

strider

When I first got my 2B's I learned my Carver M-500 wasn't completely compatible with the speakers. I built an AI-1 interface so I could use the speakers and amp together. After listening to this set up for a couple of months, fooling with the placement, I wasn't completely satisfied with the SDA affect. I ended up trying out my HK AVR520 for a bit. The SDA drivers are definitely at a higher level then with the AI-1, but the dynamics just aren't there with the internal amplification of the HK. I've searched for a bit for info on the Carver but haven't found what I'm looking for: is there a way to make this a common ground amp? If anybody has any info I'd appreciate it; I didn't find anything useful on carveraudio.com, and don't really want to ask such a newbie question in my first post! Thanks in advance,
Ben

BlueMDPicker

Have you put a VOM across the negative speaker terminals to check for common ground (probably a dumb question since you went to the trouble of building the AI-1)?

strider

BlueMDPicker wrote:

Have you put a VOM across the negative speaker terminals to check for common ground (probably a dumb question since you went to the trouble of building the AI-1)?

Actually, not a dumb question at all! I didn't try that, I just assumed what others were telling me was correct. I'll take home a voltmeter from work tonight, what exactly should I do?

BlueMDPicker

Common ground is indicated by closed, no resistance, between the two negative posts. I did some serching on your original threads, and it seems like some VERY knowledgable folks here told you it was NOT common ground. Won't hurt to throw a VOM on it for proof though. If there's no resistance, you can try strapping the grounds together. What sort of protection circuitry does the amp have (fuses, resettable breaker, etc)?

BlueMDPicker

BTW - I see you're close. If you want to try one of Polk's factory made AI-1's, you can borrow mine and see if there's any difference.

heiney9

DIYAUDIO.COM is a great resource for this type of question. Either search the archives or ask the question there. I know of a few long time members who used to do warranty work for Carver, Polk, Adcom, Nakamichi, Luxman etc., and we were just discussing the common ground issue with regards to certain Adcom amps.

One of his comments to me was "thank god your not using particular Carver amps". He goes on to say that both Polk didn't disclose this issue very well and that some amp manufacturer's weren't aware of the common ground issue at the time and Carver was one of the manufacturer's that made many models of non-common ground amps which can cause problems with some model SDA's.

Beyond that I don't know which models of Carver have issues. Post in the solid state forum and give it some time and someone will help you out.

BlueMDPicker

Luther (wardsweb) has probably owned that amp. You around Luther?

strider

BlueMDPicker wrote:

Common ground is indicated by closed, no resistance, between the two negative posts. I did some serching on your original threads, and it seems like some VERY knowledgable folks here told you it was NOT common ground. Won't hurt to throw a VOM on it for proof though. If there's no resistance, you can try strapping the grounds together. What sort of protection circuitry does the amp have (fuses, resettable breaker, etc)?

So I should have a zero in the display of the voltmeter when I put the probes on the negative terminals of the amp if it is common ground? If this is the case, and I strap the grounds together (would speaker cable be ok?), what does this do? As for the protection, I believe it has a fuse.

Thanks for the input; sorry for all the questions, as you may be able to tell my enthusiasm for things audio exceeds my knowledge by a factor of 10!

strider

BlueMDPicker wrote:

BTW - I see you're close. If you want to try one of Polk's factory made AI-1's, you can borrow mine and see if there's any difference.

I did some serching on your original threads, and it seems like some VERY knowledgable folks here told you it was NOT common ground

Man, this place is great!

heiney9

strider wrote:

So I should have a zero in the display of the voltmeter when I put the probes on the negative terminals of the amp if it is common ground? If this is the case, and I strap the grounds together (would speaker cable be ok?), what does this do? As for the protection, I believe it has a fuse.

Thanks for the input; sorry for all the questions, as you may be able to tell my enthusiasm for things audio exceeds my knowledge by a factor of 10!

Not all negative speaker terminals can be strapped. Like I said if you can have some patience at DIYAUDIO or if someone here know's 100% I wouldn't try anything until you are sure. What BlueMD states about checking the terminals with a volt meter is correct, beyond that........

BlueMDPicker

Set the VOM to ohms. You're looking for zero ohms. Strapping the negative terminals together creates a common ground on the output stage. Your AI-1 would, of course, not be required if the grounds can be strapped.

Offer still stands to try the Polk AI-1. IIRC, I've never seen anyone on the forum who was 100% satisfied with the DIY version.

strider

BlueMDPicker wrote:

Luther (wardsweb) has probably owned that amp. You around Luther?

I could be, but I'm kinda new around here and know people by screen name only. I got lucky off of Ebay on that amp, as well as a C-1 preamp.

strider

I remembered to bring a voltmeter home tonight. Touched the probes to each negative terminal and it showed an infinite resistance. Touched the probes together and it showed a negligible resistance which, to me, confirms the meters ok. I searched DIYAUDIO.COM and didn't find anything. There's a guy on the Carver Audio forum that sells owner's manuals, would it be worth it to buy one in the hopes it may have some helpful info?