I'm interested in trying a Neurochrome amp to pair with 101db horns (Wayne Parham's 7pi) Can anyone help me with sonic differences between 186, 286 and 686 amps? I'm looking smooth, transparent, effortless sound and I want to get the most out of the build in terms of sound quality without overspending on unused power. Thanks so much for the help!
Are you planning to drive ONLY the horns with the Modulus 186? No woofer driver? If so, then the Modulus 186 will be more than enough, assuming that the 101db sensitivity is accurate. NOTE: I sent to the Parham sale site and there was NO information on sensitivity, so where did you get the 101 db figure?
Assuming that the horns are, in fact 101 db sensitivity (that seems high given that Klipschorns are not rated that high in efficiency), then 1 watt will drive to the horns to 101 db. at 3 ft. distance. Why you would want to go any higher in a living room is not clear to me, but assuming you want to go to 104 db, the power doubles to 2 watts. to go to 107 db (assuming that there is no power compression), then you need 4 watts. And so forth.
re you sure that the speaker system as a whole is rated for 101 db sensitivity?
Assuming that the horns are, in fact 101 db sensitivity (that seems high given that Klipschorns are not rated that high in efficiency), then 1 watt will drive to the horns to 101 db. at 3 ft. distance. Why you would want to go any higher in a living room is not clear to me, but assuming you want to go to 104 db, the power doubles to 2 watts. to go to 107 db (assuming that there is no power compression), then you need 4 watts. And so forth.
re you sure that the speaker system as a whole is rated for 101 db sensitivity?
How large is the room, and what is your average listening level? Even derating the sensitivity by 10dB, I’d suggest the 286. I’m using one to drive a pair of modest MTMs (probably 90dB @ 1 watt?) in a 400+sq ft open plan space, and it has more than enough “torque” for my listening at well below threshold of pain / “concert levels”.
As for sonic differences between models in the Modulus series, I suspect you’d be hard pressed to identify them in a blind listening test at average listening levels. The 3886DR, yes, but I think not any of the Modulus.
As for sonic differences between models in the Modulus series, I suspect you’d be hard pressed to identify them in a blind listening test at average listening levels. The 3886DR, yes, but I think not any of the Modulus.
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On a related note, my horns Really are high efficiency (Radian 475PB-8 at 111dB/1w/1m), used actively without passive crossover.
I have/had all kinds of tube amps (45, 2A3, 300B, EL84 SE), but I notice a lack of a really stupendous low-watt (3-5 watts) solid state amp options out there at less than First Watt money.
Actually, my Icepower 1200AS2 class D amps sound pretty good on the horn, but the 600 Watts is just way overkill if there is a low-power, better-sounding non-tube option.
I plan to drive the whole system including the 15" woofers. I guess it is actually 104 db 1w/1m per this list Pi Speakers - Prices, Dimensions and Specifications
A big part of my question lies in the sound quality differences between the amps. For example, does the 686 sound the same at 1 watt as the 186 or 286?
A big part of my question lies in the sound quality differences between the amps. For example, does the 686 sound the same at 1 watt as the 186 or 286?
Not gonna second guess those rather generous sensitivity ratings, but based on my recollections of the 4 different models of Tom’s amps I’ve heard, I’d say you’d be hard pressed to identify between any of the Modulus at that power level.
And it probably wouldn’t hurt to include smart speaker protection in such a system.
And it probably wouldn’t hurt to include smart speaker protection in such a system.
Ahh, evil Google sent me to a different page.
Assuming the 104 db sensitivity and the 129 db peak output are correct, there is no power compression, then:
1 watt amplifier output = 104 db
2 watt amplifier output = 107 db
4 watt amplifier output = 110 db
8 watt amplifier output = 113 db
16 watt amplifier output = 116 db
32 watt amplifier output = 119 db
64 watt amplifier output = 121 db
128 watt amplifier output = 124 db
254 watt amplifier = 127 db
502 watt amplifier = 129 db output with a bit of margin
I believe the rule of thumb that these numbers come from assume a free field anechoic response; actual loudness in a room would likely be higher.
Unless you are going to be doing sound reinforcement, I go not believe that even the Modulus 286 is needed - which would produce 121 watts at 3 ft. According to this sitehttps://audiology-web.s3.amazonaws.com/migrated/NoiseChart_Poster-%208.5x11.pdf_5399b289427535.32730330.pdf 120 db is equivalent to a jet plane taking off; rock music concerts are at 110 db.
It is your hearing, and your pleasure mode of listening, but I suggest that the Modulus 186 is perfectly acceptable for normal, living room listening.
Assuming the 104 db sensitivity and the 129 db peak output are correct, there is no power compression, then:
1 watt amplifier output = 104 db
2 watt amplifier output = 107 db
4 watt amplifier output = 110 db
8 watt amplifier output = 113 db
16 watt amplifier output = 116 db
32 watt amplifier output = 119 db
64 watt amplifier output = 121 db
128 watt amplifier output = 124 db
254 watt amplifier = 127 db
502 watt amplifier = 129 db output with a bit of margin
I believe the rule of thumb that these numbers come from assume a free field anechoic response; actual loudness in a room would likely be higher.
Unless you are going to be doing sound reinforcement, I go not believe that even the Modulus 286 is needed - which would produce 121 watts at 3 ft. According to this sitehttps://audiology-web.s3.amazonaws.com/migrated/NoiseChart_Poster-%208.5x11.pdf_5399b289427535.32730330.pdf 120 db is equivalent to a jet plane taking off; rock music concerts are at 110 db.
It is your hearing, and your pleasure mode of listening, but I suggest that the Modulus 186 is perfectly acceptable for normal, living room listening.
A lotta folks quite like the ACA. I’ve heard several iterations of it myself driving single driver and multiways of much lower sensitivity than the Pi’s, and while they were definitely targeted to have their own flavor - unlike the very neutral design goal of the Modulus - they weren’t at all hurtful, and the full zoot kit from the DIY Audio store costs way less than the sales tax on any of the “factory” FirstWatt products.
FWIW, I’ve owned more than a few class D amps, including currently 3 channels of ICEpower 200AS, and a very early Hypex UCD180 in a modest 7.1 surround rig. While both are more than sufficient power for the application, if cost was no impediment, I’d swap them out for the 686 for LFE channel, and 286 for the front row 3, and 186 for the surrounds.
I’m starting to have increasing occurrences of HDMI/ARC dropouts on the Onkyo receiver, and may yet need to replace it, and if so would seriously consider a “budget” processor - of which there are currently few options.
I have been looking at the ACA and it might be something I try down the road. For this build, I really want to stick to something more neutral. Most of my exposure has been to tube amps and old solid state - nothing truly neutral.
Sounds like the 186 or earlier Modulus 86 would be the logical option from the Neurochrome lineup. The newer series are available only as fully assembled boards, while the 3886DR and Modulus86 are “roll your own”. My own 286 was one of the limited edition complete kits that Tom offered a couple of years ago, and while a bit of a tighter fit assembly than say the ACA, it was less than a full afternoon’s work.
I mentioned earlier that I’ve owned a plethora of class D amps - going as far back as the original Kingrex Tripath, and while there’s now an embarrassment of riches at very affordable prices in this market segment, I’ve yet to hear one at a competitive price to the Modulus that has the combination of muscularity and neutrality. Not saying they don’t exist, but there’s simply too many to choose from these days.
I mentioned earlier that I’ve owned a plethora of class D amps - going as far back as the original Kingrex Tripath, and while there’s now an embarrassment of riches at very affordable prices in this market segment, I’ve yet to hear one at a competitive price to the Modulus that has the combination of muscularity and neutrality. Not saying they don’t exist, but there’s simply too many to choose from these days.
Member Suzyj did a stunning little amp in that power range using cheap off the shelf parts. Her aim was 1ppm distortion. This would be a much cheaper option than a 5W class A amplifier.
Here's the writeup from her webpage: Suzy's Blog: 2018
And:
Cascading diamond buffers - a cheap low THD 10W amp with TIP41C
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If you have owned and built the Modulus-86, the Parallel-86, the Modulus 286 and the Modulus 686, you know what choice to make. The Modulus 686 is a tremendous main 2ch amplifier irrespective of the sensitivity of the main 2ch speakers. Oh, and my mains are 96dB/2.83V/m, enough said.
And yes I own and build Pass inspired designs too. But the 686 always stays as a reference point of comparison.
It’s not about just the peak SPL or dynamics, the Modulus 686 does tremendously well at low level listening ie, < 1 watt.
Best,
Anand.
And yes I own and build Pass inspired designs too. But the 686 always stays as a reference point of comparison.
It’s not about just the peak SPL or dynamics, the Modulus 686 does tremendously well at low level listening ie, < 1 watt.
Best,
Anand.
So jgood, as you can see advice is far too easy when spending someone else’s money, and consensus is easily reached on a DIY forum. 
Anand, as you clearly have more experience with the entire Neurochrome line, can you attest to any sonic differences amongst the flock when operating at the 1 watt level? None of the speakers on which I auditioned any of them were near the sensitivities described above, and except for the 3886DR, I couldn’t discern any; but then in my late 60s at the time, and with damage from 25yrs of industrial noise, my hearing is not as acute as 40yrs ago, or much of the cohort here.
Anand, as you clearly have more experience with the entire Neurochrome line, can you attest to any sonic differences amongst the flock when operating at the 1 watt level? None of the speakers on which I auditioned any of them were near the sensitivities described above, and except for the 3886DR, I couldn’t discern any; but then in my late 60s at the time, and with damage from 25yrs of industrial noise, my hearing is not as acute as 40yrs ago, or much of the cohort here.
