Amp is SST Son of Ampzilla by Bongiorno, not the latter all-new amp w/the same name and "II" suffix by Wyred4Sound/EJ Sarmento. Rated 100/200/400W @ 8/4/2-ohms, single 1k VA toroidal transformer, 100k uF PS filter, 55# net, a serious piece of kit by a person credited with creating the ubiquitous balanced differential circuit.
Can readers predict (say, within a range) the dB difference between using one SOA/Bongiorno in stereo vs. two SOA, one SOA p/c and one channel per each amp? One professional suggested 6 dB difference obviously favoring the latter, which sounds high to me.
I have a huge selection of power Rs. I have only one SOA. I considered listening to one channel of one SOA > one speaker channel and assembling a big bank of power Rs for the other unused channel, comparing the Rs to no Rs/no load. The speaker is 4-ohms nominal with a reasonable EPDR. If this is a good idea, please define the recommended R load and minimum power.
Thanks.
Can readers predict (say, within a range) the dB difference between using one SOA/Bongiorno in stereo vs. two SOA, one SOA p/c and one channel per each amp? One professional suggested 6 dB difference obviously favoring the latter, which sounds high to me.
I have a huge selection of power Rs. I have only one SOA. I considered listening to one channel of one SOA > one speaker channel and assembling a big bank of power Rs for the other unused channel, comparing the Rs to no Rs/no load. The speaker is 4-ohms nominal with a reasonable EPDR. If this is a good idea, please define the recommended R load and minimum power.
Thanks.
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Balanced output voltage using both channels with a phase inverter at one input would be twice the unbalanced, or +6dB.
20 x log 2 = 6.02dB
20 x log 2 = 6.02dB
Sorry, I may be confused, not the first time. I'm talking about using 1 ch vs. 2 chs of a stereo amp. I don't know how balanced vs. unbalanced figures into this. But for the record, the source is balanced as is the amp fully balanced differential from input to output.
The amp has floating grounds if that matters which I doubt.
The amp has floating grounds if that matters which I doubt.
Then you mean leaving one channel of each amplifier unused?
That would make no significant difference in the other channel.
If you do that, insert a shorting plug into the unused channel's input jack.
That would make no significant difference in the other channel.
If you do that, insert a shorting plug into the unused channel's input jack.
In both cases we measure maximum output of only the L ch alone.
A: The R channel is also in use, the same source feeds both L and R inputs, the L and R channels each have duplicate separate 4-ohm loads.
B: No input and no load on the R channel.
I am pretty sure I finally worded this correctly, sorry for my error above!
In case it matters, the speaker load is a satellite, dual sealed 8s with natural cutoff around 140 Hz and a horn/CD.
A: The R channel is also in use, the same source feeds both L and R inputs, the L and R channels each have duplicate separate 4-ohm loads.
B: No input and no load on the R channel.
I am pretty sure I finally worded this correctly, sorry for my error above!
In case it matters, the speaker load is a satellite, dual sealed 8s with natural cutoff around 140 Hz and a horn/CD.
Driving both channels, instead of just one, would tend to reduce the maximum output power at a given distortion level,
especially with 4 ohm loads. But it won't be enough difference to worry about, or notice.
Be careful if you decide to do any extended high power testing, since this can damage amplifiers.
Few audio amplifiers are truly intended to do that.
especially with 4 ohm loads. But it won't be enough difference to worry about, or notice.
Be careful if you decide to do any extended high power testing, since this can damage amplifiers.
Few audio amplifiers are truly intended to do that.
I knew two full time pros who liked the difference enough (1 amp vs. 2, 2 defined by my B choice above) that they both bought a 2nd amp to use as defined in B. Not arguing anything, just stating what happened.
Likely totally unrelated: IIRC there's only about 11 dB of separation between 2 human ears, defined by the skull, its shape and soft matter therein. I often wondered how or why a difference in channel separation much beyond 11 dB could or would be audible because of the above fact.
Likely totally unrelated: IIRC there's only about 11 dB of separation between 2 human ears, defined by the skull, its shape and soft matter therein. I often wondered how or why a difference in channel separation much beyond 11 dB could or would be audible because of the above fact.
This has been done in the past, even with preamps. It would make more sense though to just buy monoblocks.
You have a point about channel separation, although there are some more subtle points involved.
Separation may decrease at higher frequencies, which could be audible.
You have a point about channel separation, although there are some more subtle points involved.
Separation may decrease at higher frequencies, which could be audible.
Rayma: thanks. Just to confirm: you state my B scenario would measure about or almost the same as A?
SOA released 2001-2002; mono "Ampzilla" in 2000. The designer admitted the stereo SOA was more refined than Ampzilla while of course the mono version made twice as much power. SOA cannot be bridged because its output grounds float. Later came Ampzilla II mono with SOA's refinements. The 2 above mentioned pros preferred two SOA (using one channel in each) over Ampzilla, prior to Ampzilla II's release.
SOA released 2001-2002; mono "Ampzilla" in 2000. The designer admitted the stereo SOA was more refined than Ampzilla while of course the mono version made twice as much power. SOA cannot be bridged because its output grounds float. Later came Ampzilla II mono with SOA's refinements. The 2 above mentioned pros preferred two SOA (using one channel in each) over Ampzilla, prior to Ampzilla II's release.