Pass vs. Pass
heiney9
Posts: 25,395
I have been having so much fun with the Pass ACA (Amp Camp Amp) in my office rig. Running a few different pre's and dac's. It really performs at a level it shouldn't considering it's a basic DIY circuit. The highest expense is the case. Need something robust to dissipate the heat of single ended class A.
It has excellent bass, better than the other 2 amps I use in my office rig. I ended up having to do add some upgraded parts to the dac and pre I use to keep up. I installed discrete op-amps in a couple pieces which yielded even better sound.
This is an 8-9 wpc single ended class A amp using a 24V 5A switching power supply.
I decided to put it in the main rig to see how it would do. It blew me away. Drove the L600's to higher spl than I thought possible and didn't seem to break a sweat. Bass was plentiful, mids were excellent w/little coloration and the highs were present in spades. On it's own it sound like a really great amplifier. (within the constraints of the power output)
But then I hooked the XA25 up and well...........not really fair to compare a $5500 amp to a $359 amp.
I will say the differences while noticeable and the XA25 being sublime in every category the similarities were eye opening.
The ACA as a stereo amp has a damping factor of 10 the XA25 100. But the quality and quantity of the bass was closer than the numbers would suggest.
The highs of the ACA were less precise and more smeared than the XA25. Lower mid the XA25 had more bloom and substance.
Had I not compared the ACA directly with the XA25...........the ACA, especially as mono's, could have been a main rig contender.
The conclusion is the ACA is a superb amp by any standard (unless you are needing high spl or have a very large room).
This Fall/Winter I'll be building a mono pair and I've heard the mono's are better than the stereo version.
Some pics for fun.
H9
P.s. the above was for fun. Scale and dynamics were a bit lower than one might want, but I was listening at normal to mid level output and it filled the room with rich, open sound. Is the amp going to recreate the canon shot on the Telarc disc? No.
It has excellent bass, better than the other 2 amps I use in my office rig. I ended up having to do add some upgraded parts to the dac and pre I use to keep up. I installed discrete op-amps in a couple pieces which yielded even better sound.
This is an 8-9 wpc single ended class A amp using a 24V 5A switching power supply.
I decided to put it in the main rig to see how it would do. It blew me away. Drove the L600's to higher spl than I thought possible and didn't seem to break a sweat. Bass was plentiful, mids were excellent w/little coloration and the highs were present in spades. On it's own it sound like a really great amplifier. (within the constraints of the power output)
But then I hooked the XA25 up and well...........not really fair to compare a $5500 amp to a $359 amp.
I will say the differences while noticeable and the XA25 being sublime in every category the similarities were eye opening.
The ACA as a stereo amp has a damping factor of 10 the XA25 100. But the quality and quantity of the bass was closer than the numbers would suggest.
The highs of the ACA were less precise and more smeared than the XA25. Lower mid the XA25 had more bloom and substance.
Had I not compared the ACA directly with the XA25...........the ACA, especially as mono's, could have been a main rig contender.
The conclusion is the ACA is a superb amp by any standard (unless you are needing high spl or have a very large room).
This Fall/Winter I'll be building a mono pair and I've heard the mono's are better than the stereo version.
Some pics for fun.
H9
P.s. the above was for fun. Scale and dynamics were a bit lower than one might want, but I was listening at normal to mid level output and it filled the room with rich, open sound. Is the amp going to recreate the canon shot on the Telarc disc? No.
"Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass Pass Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Puritan Audio PSM136 Pwr Condtioner & Classic PC's | Legend L600 | Roon Nucleus 1 w/LPS - Tubes add soul!
Comments
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Hard to beat Class A amps for sound quality.
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Good insight! I've been entertaining the idea of running mono ACAs with a pair of high efficiency speakers for a while now.2ch rig: Speakers: Magnepan LRS w/Magna Riser stands Preamplifier: Parasound P5 Amplifier: Parasound A23 CDP: Pioneer DV-563A Cables: Wireworld Equinox 7 XLR ICs, Wireworld Ultraviolet 7 USB, AudioQuest Q2s, AudioQuest NRG X(preamp)
Standby: LSi9s with VR3's Fortress mods -
Good insight! I've been entertaining the idea of running mono ACAs with a pair of high efficiency speakers for a while now.
They're not bad at all (compared to SE 2A3) IME (and for whatever my experience is worth).
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I just checked the specs on the L600s: 4ohm, sensitivity 86db. Sounds like one ACA should be able to drive something like the Klipsch RP-600Ms just fine.2ch rig: Speakers: Magnepan LRS w/Magna Riser stands Preamplifier: Parasound P5 Amplifier: Parasound A23 CDP: Pioneer DV-563A Cables: Wireworld Equinox 7 XLR ICs, Wireworld Ultraviolet 7 USB, AudioQuest Q2s, AudioQuest NRG X(preamp)
Standby: LSi9s with VR3's Fortress mods -
We're about 104 dB per watt at 1 meter here (albeit at nominally 16 ohm impedance).
