To mono or not to mono?

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  • 01-26-2006, 10:45 AM
    To mono or not to mono?
    There's a pair of PS Audio 250's available on eBay for a pittance right now, and while I tend to favor the convenience of stereo amps, I also find that in everything else I prefer seperates over integrated components. So I know this is probably a silly question, but what are the advantages of using dual mono amps? Is the difference really audible if everything from input to output to power is entirely seperate? And what about amps that have dual-mono channels but a single power supply? And does this also mean that I would benefit from seperate channels in the preamp (KAVD sells a preamp like that, the Kavent S-22 for a decent price)?
  • 01-26-2006, 11:06 AM
    Resident Loser
    Pretty much the same...
    ...as going from a receiver to separates IMO...two separate power supplies neither taxing the other...more power, perhaps better headroom, higher ouput current...

    jimHJJ(...no guarantees, but the possibility is there...)
  • 01-26-2006, 11:30 AM
    Sir Terrence the Terrible
    Just to add to Jim response, no crosstalk between channels and better imaging.
  • 01-26-2006, 12:41 PM
    Geoffcin
    Dual mono
    Quote:

    Originally Posted by nightflier
    There's a pair of PS Audio 250's available on eBay for a pittance right now, and while I tend to favor the convenience of stereo amps, I also find that in everything else I prefer seperates over integrated components. So I know this is probably a silly question, but what are the advantages of using dual mono amps? Is the difference really audible if everything from input to output to power is entirely seperate? And what about amps that have dual-mono channels but a single power supply? And does this also mean that I would benefit from seperate channels in the preamp (KAVD sells a preamp like that, the Kavent S-22 for a decent price)?

    True dual mono amps have two power supplies in the chassis. My Musical Fildelity amp sports this feature. The only thing better is monoblocks, like the PS Audio monsters your looking at. You can drive any speaker on earth with those two bruisers!
  • 01-26-2006, 02:49 PM
    WILLIAM C WALDECKER 3RD
    I am on my third pair of monoblocks and will never go back to a single stereo amplifier again. it offers yet another degree of seperation and a seperate power supply for each channel seems to make them perform more effortlessly with plenty of power in reserve. i am currently a BETA tester for a pair of Modified SS monoblocks and i am really loving life right now. i would buy the PS Audio 250 monoblocks in a heartbeat if i were you. thanks....WCW III
  • 01-27-2006, 10:27 AM
    Sir Terrence the Terrible
    I have also strayed away from multichannel amps where all channels share the same power supply. I have gone to the discrete dual mono design and I am pretty pleased at the sound of my amps.
  • 01-27-2006, 04:24 PM
    C'est la vie!
    Those monoblocks are already over $500 (maybe I shouldn't have mentioned them in this post).

    Ironically, I have two PS Audio HCA-2's and these are one of the few stereo amps that are not bridgeable. I would have liked to see what they could do by temselves.
  • 02-01-2006, 12:11 AM
    I have seen the light: Class A monoblocks!
    Quote:

    Originally Posted by Sir Terrence the Terrible
    I have also strayed away from multichannel amps where all channels share the same power supply. I have gone to the discrete dual mono design and I am pretty pleased at the sound of my amps.

    OK, I was not able to get the PS Audio 250 Deltas, but I asked a friend who scored a pair of Parasound Halo JC1 mono amps from GG when they were going out of business and he invited me over for a look-see-listen. I brought my HCA-2 to do some comparisons. Saying that I was overwhelmed would be modest. Now I know that the amps are entirely different and I also can't say if it was the 400W or the fact that they were monos that made the difference, but they were strikingly different. There was more detail, more bass, and more depth in the room when we were listeing to the monoblocks. It certainly made me rethink how good that HCA-2 really is. We were driving a pair of Dynaudio speakers which I know are hard to drive, too, so that may also play into it.

    But realistically, I just don't have deep pockets like that and those JC1's are probably not going to land in my living room anytime soon. So getting back to a down-to-earth mono vs stereo amp discussion, what are some dual mono amp make/models I could take a look at on the used market?

    Also, I've been reading a bit about Class A amps like the ones from Pass Labs. They have typically much lower wattage ratings and that worries me a bit. I have to believe that the high output of the JC1 and similar units from Adcom etc. are capable of a lot more bass & depth. How does a 300-400W class A/B amp stack up against a Class A amp?
  • 02-01-2006, 12:52 PM
    topspeed
    Wattage has nothing to do with it. What good are 400w monos with a 99dB/w/m hi-efficiency speaker? Pay attention to current and damping factors. This is what gives an amplifier the ability to control the speaker.

    Also, while Danes are usually 4 ohm nominal speakers, switching amps are load invariant so I doubt that had anything to do with it. Did you use an spl meter to make sure your comparisons were level matched? Gain differences in the JC1's (awesome amps btw) and HCA2 could have contributed to the perceived difference in detail and depth.

    Finally, there simply might have been better synergy between the JC1's and Danes than with the PSA. It doesn't necessarily mean the JC1's are always going to sound better, only that they sounded better on that rig. This is not to take anything away from the Halo's, btw. As mentioned, they are awesome amps, and at 4X the price of the HCA2, they damn well better be ;).

    Nelson Pass, as with John Curl, are legends in the audio world. These guys have forgotten more about good amp design than most will ever know. Pass Lab amps, like his previous Threshold offerings, are emminently listenable. Instead of worrying about lower watt ratings, just borrow one and plug it into your rig and see for yourself. Watts are overrated.

    You can do a search here for the difference between Class A and A/B amps. You'll find proponents for both. The class designation has nothing to do with quality and everything to do with topology. One thing is for sure, pure Class A designs tend to run as hot as a firecracker and consume LOTS of power, so consider yourself forewarned.
  • 02-01-2006, 03:34 PM
    SlumpBuster
    Quote:

    Originally Posted by topspeed
    You can do a search here for the difference between Class A and A/B amps. You'll find proponents for both. The class designation has nothing to do with quality and everything to do with topology. One thing is for sure, pure Class A designs tend to run as hot as a firecracker and consume LOTS of power, so consider yourself forewarned.

    Yeah, you may want to take a very close look at the A vs. A/B debate. Yamaha made a series of amps in the 80's with class A operation up to 10 to 20 watts depending on the model. I have one of these amps and love it. But interestingly it as a button on the front that allows the user to select A vs. A/B. Now I can't hear any difference, but can feel the difference. It gets wicked hot. It couldn't stay with other components in my rack, too hot. If you go with a class A design, make sure you have a dedicated place for it.

    Also, just because I can't hear a difference, it doesn't stop me from running class A for music, and A/B for movies. It is fun to fool around with it.
  • 02-02-2006, 01:48 PM
    I got lucky
    Well it turns out that I got a second-chance offer on the PS Audio Monoblocks. I can't wait to hear what these will do. They are rated at 400W (4 ohm) and although they are Class A/B (correct me if I'm wrong), they are capable of "over 150 Amps of instantaneous peak current" according to PS Audio.

    I can't wait to hook these up to my MB Quarts as I have always felt that those speakers required far more power than my HCA-2 was feeding them. They certainly had more detailed lows on a B&K Reference 4420 (350W) I had here, but that last amp wasn't mine to keep. Maybe they'll even hold up against the JC1's - wouldn't that be a kick in the pants!
  • 02-02-2006, 03:50 PM
    Geoffcin
    Be careful with the second chance offer on Ebay
    Quote:

    Originally Posted by nightflier
    Well it turns out that I got a second-chance offer on the PS Audio Monoblocks. I can't wait to hear what these will do. They are rated at 400W (4 ohm) and although they are Class A/B (correct me if I'm wrong), they are capable of "over 150 Amps of instantaneous peak current" according to PS Audio.

    I can't wait to hook these up to my MB Quarts as I have always felt that those speakers required far more power than my HCA-2 was feeding them. They certainly had more detailed lows on a B&K Reference 4420 (350W) I had here, but that last amp wasn't mine to keep. Maybe they'll even hold up against the JC1's - wouldn't that be a kick in the pants!

    There's a lot of scams running using this. I received an "offer" after I lost a bid on a PS Audio 200 preamp and it was phoney.
  • 02-03-2006, 10:52 AM
    Legit
    Quote:

    Originally Posted by Geoffcin
    There's a lot of scams running using this. I received an "offer" after I lost a bid on a PS Audio 200 preamp and it was phoney.

    Actually, this one was legit. The offer came from within eBay. I will be picking these up this weekend (the seller is local). Can't wait.