2. amps-preamps
  3. 1042611447

If i had the money.....

I'd be ordering a set of the Parasound Halo JC-1 Monoblocks. I knew that these were going to be good, but i didn't know just HOW good. I've talked to a few people that have them and the "reviews" of these end users is just as strong as the recommendation that these amps receive in the February Stereophile.

Hard to imagine beating a product that was designed for optimum linearity / performance by an audio legend, laid out by an RF engineer in order to maintain consistent impedances throughout the entire circuit and then building the circuit with each part hand picked to "voice" the unit for optimum sonics by a "tweaker". The total approach to product building for $6K a pair !!! All of this with POWER to spare !!!

THD is predominantly all second harmonic i.e. not the typical odd order that most SS amps generate.

IMD of .0015 !!! Keep in mind that distortion typically goes up quite noticeably as power is raised and impedance lowered. This figure was taken at 4 ohms and at 600+ watts of output !!!

Output impedance of no higher than .06 ohms. This amp should keep the same "voice" and stability into just about any speaker. The power output verifies the stability and "robustness" of the circuit also....

Rated at 400 wpc @ 8 ohms

Power at clipping, broad band signal steady state:

8 ohms: 545 watts

Power at clipping, pulsed 1 KHz signal:

8 ohms: 586 watts

4 ohms: 1154 watts

2 ohms: 2255 watts

1 ohm: 4200 watts !!!

Any thougths / comments on this one ? Sean
>
sean
rcrump
427 posts
 
Voicing is easy, just parts choices based upon twenty-five years of playing with various parts....I keep a journal of what various parts do in various parts of a circuit as most resistors measure pretty much the same and they all sound different in use as do caps, wires, switches and connectors....You do it long enough and you can look at a piece and tell what it will sound like just looking at the parts used.....I come from the school of get your hands dirty, take notes and before long it will start making sense.....Voicing the Parasound amp took about a year and a half of work on the HCA-3500 I used as a prototype and then a few months with the JC-1 prototypes before the units went into production....The bulk of the time was in break-in as I rebuilt the HCA-3500 in several stages......I voice for complete break-in and complete warm-up, 60 days and 5 days.....
tok20000's avatar
tok20000
608 posts
 
Rcrump,

I was just stating that stats on amps are misleading. As you reinforced with your response to my previous post. Different types of distortion can mean different things to one's ears.

However, I will still maintain that stats can be very misleading while many times having little to do with how an amplifier sounds. I am sure you are familiar with the THD wars in the 80's when the theory was that the least Total Harmonic Distortion was BEST. This THD war was nonsense.

Anyway, I can look at stats all day in a magazine about amps and really have no idea on how those amps will sound in my system. Too many stats are misleading at best. For example the 'dampening factor' stat. This stat is touted by many amp designers; however, measuring dampening factor is something else entirely. The stat itself varies with the length of speaker cable you are running. Thus if you want more 'damping factor' you do the measurement with a shorter run of speaker cable.

KF
rcrump
427 posts
 
Tok2000, I certainly agree as, other than S/N, spectral analysis and shipping weight (for when it breaks) most of the specs don't mean much.....I don't deal with these, but my partner sure does going on about higher order odd harmonics big time.....I just deal in sound and hopefully some folks will like the way the JC-1 sounds....I do and guess that is what really matters in the long run as I am happy with the results.....
sean OP
6,231 posts
 
Once again Tok20000, one has to look at ALL the specs and know what they mean / how they are arrived at to know what to make of them.

As far as your comments go about damping factor, that is the ratio that compares the output impedance of the amplifier to the load impedance of the circuit. As such, one would have to run a LOT of speaker cable to drastically alter the load impedance that the amp sees. That, or use REALLY small gauge speaker cables. Otherwise, using twice the length of cable if using a "reasonable" gauge speaker cable ( like at least 16 or 14 gauge ) wouldn't make any "real" difference in damping factor at all.

As far as your comments about low THD and the "distortion wars" of yesteryear go, i agree. The designers sacrificed a lot of other important design criteria to concentrate on achieving good specs in the area of measurable distortions. They did this using high amounts of negative feedback. Having said that, if one knew about specs, you could look at the distortion measurements AND the amount of feedback used and draw conclusions by putting 2+2 together. It is not a matter of any one spec being more important than the other, but how the various specs affect each other and work as a whole.

Mr Crump: I had no idea as to what your email was talking about until i saw this thread. I kind of wondered how you ended up talking about the CD player project when we were discussing something else : ) Sean
>
rcrump
427 posts
 
Cdc asked about a smaller amp and I told him what we had in mind as our next project....Parasound wanted a preamp, but think I have them convinced that the world didn't need another 3-4K preamp, but needed a really good CDP with some preamp functions.....
More to discover