Common Ground Question - Ampzilla or A-S801?
MATT0404
Posts: 7
I'll be picking up a pair of SDA SRS 2's (blade/blade) this weekend and I'm trying to figure out if I have an amp capable of driving them.
My go-to high power, high current amp is a GAS Ampzilla that's had Mike Bettinger's reference restoration with JFET input stage, but I'm not sure if it's a common ground amp. Has anyone used an Ampzilla to power their SDA's in the past?
Another amp choice would be a Yamaha A-S801 integrated with 100 wpc @ 8 ohms, and ~185 wpc @ 4 ohms. Again, though, I'm not sure if this is a common ground amp.
My last option would be a restored Sansui AU-999 integrated, but I'm almost certain it would run out of steam rather quick.
Can anyone here offer some insight into whether any of these amps are compatible with SDA's?
My go-to high power, high current amp is a GAS Ampzilla that's had Mike Bettinger's reference restoration with JFET input stage, but I'm not sure if it's a common ground amp. Has anyone used an Ampzilla to power their SDA's in the past?
Another amp choice would be a Yamaha A-S801 integrated with 100 wpc @ 8 ohms, and ~185 wpc @ 4 ohms. Again, though, I'm not sure if this is a common ground amp.
My last option would be a restored Sansui AU-999 integrated, but I'm almost certain it would run out of steam rather quick.
Can anyone here offer some insight into whether any of these amps are compatible with SDA's?
Comments
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Far as I know, ALL Ampzillas are balanced/bridged...therefore NOT common-ground.
The usual advice: Test with ohmmeter across the negative terminals of the two channels. You'll want LESS THAN one ohm. -
My mind just broke. It's kind of hard to imagine two more diametrically opposed amplifiers (if only philosophically) than an Ampzilla and a modern Yamaha
Nothing against either -- I loved the GAS stuff in those days and I have a Thoebe preamp, and I just may be a bit of a Yamaha fanboy -- but, what a pair from which to chose!
Sorry, no idea about ground topology, but, yeah, should be easily sussed out with a DMM, VOM or VTVM
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The schematic of the original Ampzilla shows it to be common ground.
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Am I wrong? I was certain that one of the "big deals" about Ampzilla was that it was among the first amplifiers to have a balanced output circuit. Fairly certain Jimmy B. was proud of that deal, and continued with it with Sumo and eventually Ampzilla 2000.The schematic of the original Ampzilla shows it to be common ground.
If it's balanced, it's not common-ground. If I'm wrong, it could be.
The ohmmeter will tell the tale.
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The original Ampzilla is a fully complementary symmetrical design ,the negative binding post is tied to ground.Thus common ground.Later units Ampzilla III and 2000 look to have balanced/bridged output stages so are not common ground.
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Am I wrong? I was certain that one of the "big deals" about Ampzilla was that it was among the first amplifiers to have a balanced output circuit. Fairly certain Jimmy B. was proud of that deal, and continued with it with Sumo and eventually Ampzilla 2000.The schematic of the original Ampzilla shows it to be common ground.
If it's balanced, it's not common-ground. If I'm wrong, it could be.
The ohmmeter will tell the tale.
The big deals about the Ampzilla, as I remember, were that it was powerful as heck, it was somewhat less likely to self-immolate than Carver's Flame Linear amplifiers of the day, and it was EVIL looking.
source: http://www.tnt-audio.com/edcorner/january13.html
In seriousness, the late Jim Bongiornio was a fine fellow who was responsible for a number of good sounding products (from Dynaco, SAE, GAS, Sumo and his "Ampzilla 2000".
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Bonzo was a clever fellow and apparently quite a character.
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Oh, yes, quite a character was James "Bongo" Bongiorno. Quite the fashion plate.
(edit: heh - I mistyped his name in my previous post; sorry!)
He was very active for a while on the FMtunerinfo forum (his GAS/Sumo "Charlie" tuner gave him ample cred in that domain!) -- but he tired of the morons there & vacated.
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Ah my bad "Bongo'' not "Bonzo".
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Really!Morons on an audio forum?mhardy6647 wrote: »...while on the FMtunerinfo forum (his GAS/Sumo "Charlie" tuner gave him ample cred in that domain!) -- but he tired of the morons there & vacated.
Quite the dresser. That pank suit is kind of ummmm... different.
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Really!Morons on an audio forum?mhardy6647 wrote: »...while on the FMtunerinfo forum (his GAS/Sumo "Charlie" tuner gave him ample cred in that domain!) -- but he tired of the morons there & vacated.
Quite the dresser. That pank suit is kind of ummmm... different.
After they made James, they broke the mold.
There's this thing on hifi forums (no, not that thing) -- if real, actual experts join & post, they get hounded by schlubs who insist that they (i.e., the aforementioned experts) are clueless. Usually the actual experts get tired of the plebians & move along. Sometimes it gets pretty ugly (oxymoronic a phrase though that be); in the FMtunerinfo/Bongiorno case, it got pretty ugly. Bongiorno didn't suffer fools graciously.
Ken Kantor (of NHT fame) was at AK for quite a while but finally got tired of the dweebs who in essence told him he didn't know what he was talking about -- and he faded into the background (which was a real shame, IMO).
Legendary creator/editor of Sound Practices, Joe Roberts, is active at AK, too. He's not quite from the same part of the food chain as the aforementioned designers, though, so folks actually treat him pretty well there -- and he's a great guy (and a hifi enabler, too), so he seems to sort of be a non-example of the usual phenomenon.
