Parasound JC1's vs. Sim Audio W10

I am looking for amps to drive some MBL 101d's and wonder which of these two monoblocks would work the best. Or any other suggestions that you might have.
I look at the back of the Parasounds and see the cheapest plastic 5way binding posts and wonder what else is junk inside if thats the quality on the outside? the Sims are pure quality but you can do better musiclly. A McCormack DNA 500, Belles Ref.150 in mono,Ayre(the big one),BEL-Brown Electronics Labs mk5 in mono,Clayton mono's all will beat the Mark Levensons, Krells, Pass,Jeff Rowland Plinius,Classe etc,etc. I don't believe stereo or mono amps will effect the soundstaging nearly as much as the speakers output being exactly the same. And though I am fully ballanced with my system, I don't put any advantage or dissadvantage in going ballanced or single ended.
Before you start trashing a product, get your facts straight. The "cheap plastic" binding posts on the JC-1's are Superior Electric binding posts, and they are not cheap junk, and were chosen by co-designer Bob Crump as sounding superior over numerous other choices. I hardly think that the numerous massive Nichicon Gold Tune caps or the Vishay resistors inside qualify as anything other than parts among the highest quality and cost available today.
Mahandave, those binding posts on the Parasounds were chosen for a reason, that overall they sound better than anything else... Superior Electric binding posts are the original, much imitated with a lot of cheap lookalikes that don't sound anywhere close to the same... If you still can't get over the appearance then I suggest you take a look inside and you will be surprised... More importantly, find a dealer who has fully broken-in JC-1s that are available for home trial and listen for yourself... One of the nice things about the JC-1s is that they don't need to be hotrodded, as they come that way from the factory...

Brian Walsh
I don't believe the larger Ayre amp sounds as good as the V5x.
As a very satisfied owner of the exceptional JC-1 monoblock amps, I must defend them from the undeserving attack about the build quality, and parts quality by the first responder to this thread!
The JC-1's have no "junk" parts on the inside or outside!
They are built like a tank, and use some of the highest quality and best sounding parts currently available!
I have no problem at all with the Superior Electric binding posts. The JC-1's have received rave reviews from the audio press as well as audiophiles for their excellent sound, PARTS QUALITY, and build quality! As Brian Walsh said, they are factory hot rods!
And you MUST give them their required LONG break-in period, or you will never know just how exceptional they can sound!
I will also give the JC-1s my highest recommendation based on extensive listening to my best buddy's system which includes a pair of these amps. I certainly won't say they are the best amps available, but they certainly ARE among the very best available at ANY price, IMO. They are well built, with very high parts quality (just pop the lid on one of these puppies to see what I'm talking about).

Krevzeik: I think you should refrain from making such bold statements like you did in this thread without first, knowing all the facts and second, you better be able to back up what you say or you should specify that your statements are based on your opinion and not fact. You shouldn't trash a product without first knowing the facts. Please do your homework before typing.
In all due respect, I think you meant Mahandave instead of Krevzeik as the one criticizing the JC-1's.
Krevzeik defended the JC-1's.
Thanks Timo.
i had recently bought a pair of jc-1s and also had a negative experience. after hooking them up, noticed a low level buzz coming from one mono block when you were close to it. called parasound and was told this was "normal". when i told rep. the other was dead quiet, his response was,"well, that one is beyond spec." a second problem was one of the standby lights on the front panel did not function properly, and this prompted the dealer to take them back and get me a new pair. i hooked up the new pair, and played them for about 20mins, and heard a loud pop. one of the monoblocks had "blown" (not a fuse), and quit working. at this point, i had had enough. they went back to the dealer and i am currently waiting on a new amp from a different manufacturer. the parasounds may be great sounding amps, but my experience speaks to the overall build quality and quality assurance.
The JC-1s are good. On a demanding speaker, however, they must be run in low bias mode, which does sacrifice some sound quality.
My apologies Krevzeik. Daltonlanny, you are correct. I meant to direct my comments to MahanDave.
As an owner of a pair of JC1's which I run through a Moon P-5 pre, I would have to say that you have no idea about the JC1. Please open the top of one of these and see for yourself whats inside before rushing in to comment about them!

Since I already had the Moon P-5 pre before I bought the JC1, I naturally looked at Moon Power Amps. Having chosen the JC1 over the W6 should indicate the quality of the JC1's. In fact most magazines, including Stereophile who gave JC1's a fab review don't even have any ads endorsed by Parasound in their magazines. This should also be indicative to the build quality of these amps & their sound. Go ahead hear them have a look and then you are more than welcome to comment!!
Nothing wrong with the build quality of the JC-1! It is nothing short of amazing to get the parts quality inside that those bad boys (for the money or any other way you want to express that)exibit. I have seen a lot worse out of some much more expensive products.
I didn't warm up to the amps (but it could have been an issue with breakin, want deny that) but they were a couple of the best built amps I have seen.
Gladstone, I run my JC-1s in high bias 24/7 and have for a couple years for both my Rockports (an easy load) and my Sound Lab M-1s (tough load) and curious what speakers are a tougher load than the Sound Labs? I chose the parts in the units and will say that those cheap Superior Electric posts cost five times as much as what is normally used by Parasound, are the originals that everyone copied and eat things like the WBT, Edison Price and Cardas binding posts. They were chosen for their performance, not their pricing. The JC-1 is what it is, a very powerful amplifier that can be machine built in Taiwan using specified parts that also sounds very good.........Sure we could do better if the retail pricing was 25K/pr........

Bob Crump
CTC Builders
Cadougie - there are a couple of reliability things that could use improvement, mostly in older used JC-1's. Parasound is aware of these and some of these have been improved in the newer versions. I'm surprised that you had problems with a recent amp - perhaps it was from an older build lot.

I resolder all of the power transistor solder joints because some of these are not good in the older amps. The open-frame pots used for the bias adjustment seem to drift (or the other components drift), and finally, the inrush limiters do not have a lot of margin, so I use higher current versions. Once these things are changed, it is a very robust amp. I have had mine for several years and use it every day.
Bob. What is the difference between high and low bias on a practical and sound quality level?.

thanks Shane
Hi Shane,

In low bias the unit will go into AB mode at about 10w which is audible with my Rockport speakers and isn't in high bias which allows about 30w of class A. I normally run the amps 24/7 in low bias and flip the switches to high bias when I want to listen to anything above tuner level......This saves a bit on heat and electricity and is a useful feature on this large amp........

Is it ok to turn the JC-1's on and off every day or does it take to much of a toll on them? I prefer to do this but certainly do not want to hurt the amps. Thanks for your responce
Break in time. Bob I am going to have listen one more time to a pair of JC-1's in the next couple of weeks.

What is the minimum play time until these amps will show most of what they are worth and sound pretty nice.

I had a listen to a pair 6 months ago and frankly was underwelmed - they had about 100-150 hours on them and I ran them in for another 50 of so. The dealer in total has probably only put about 300 hours max even now. He much prefers the sound of the moon W5 and has dismissed the JC-1's as he believes the long play time as garbage.

Bear in mind that the dealer is not going to let me play these amps for 1500 hours, and I am not going to buy anything on the promise of fundamental changes in sound at a later stage.

I would appreciate your honest oipen opinion as always.

cheers Shane

I know a number of people who have these amps (including myslef), and I am pretty sure all of them will tell you that prior to about 1200 hours, they relly do not shine. After that initial 1200 to 1500 hours they are a totally different amp. Feel free to e-mail me if you want to discuss them over the phone.
I have no doubt these are fine amps when the breakin time is up, judging from the great endorsements I have read by so many folks. What bothers me is that should I buy a pair, and I am interested, I will have to play them on average 10 hours a day for 4-5 months before they deliver the performance I have paid for. That is a Hell of a long wait and if they sound lousy during that period, I don't think I would buy them, for that reason alone.

Can you please explain if there is a way to speed up the burn-in,and comment on the sound quality during this period. Will I enjoy my music during this time, or will I get discouraged?When I see these for sale on A-gon, I wonder if that is in fact the situation that has befallen the seller.
Thanks, Carl
Hi Shane,

Break-in time with the JC-1s is horrible as it takes right at 30 days for the thinness to go away and almost 60 days for units to open up. Why? Probably the huge Nichicon caps if I had to point a finger, but not certain........
Brrgrr, the amps go through ups and downs during break-in, but the worst is the first thirty days whilst they go between brilliant to thin......They settle down after thirty days and go dull and finally wake up at about 55-60 days and stay there........I just leave the tuner on and play the system at a low level 24/7.........
Bob, Just out of curiousity....what is the reason capacitors need so long to settle in? I have noticed the same thing in my VR4jr's recently.....suddenly, they are a changed speaker, and very much for the better.

Both the Nichicon and the Black Gate use an unusual electrolyte and there are some oil filled caps that take a while to break-in as well.........JC-1s go through a similar phenomenon as the VR4jrs as imagine they were dull as dirt from 35-55 days and then opened up big time........Had a similar problem with WBT binding posts so lord knows what is the cause, but Curl thinks he has tracked down the severe break-in problem on the JC-1s to the high current Nichicon caps.......Whatever it is on the VR4jrs the way to proceed is to talk to the manufacturer and get his take on break-in as some of the better parts take inordinate times to open up..........I would get the manufacturer's take on break-in times and run with it........Funny, but some of the cheapest parts break in easier than the fancy spreads.......
Thanks for your input, Bob! I own a pair of JC1's and love them with my Magnepan's.

It's usually reported that most high-end companies do extensive listening to select parts, design, etc. How do long breakin parts factor into this process? It seems it would take an enormous amount of time to settle upon the best mix if you had to wait for parts to breakin this long? Do you limit the parts to a select few based on circuit analysis and/or experience?

Hi Jordan......I spent a couple years updating the HCA-3500 before specifying parts for the JC-1s. I spent over ten years working out the passive parts for the CTC Blowtorch.......This included break-in of 30-60 days per change so lots of patience involved.......Circuit analysis is the job of the electrical engineer and voicing the circuit is a job for a listener........I have been taking notes for the past 25 years and keep a book of the changes I hear in parts, but, of course, have my favorites.......It is rare I run into trouble (going backwards) any longer, but I sure did twenty years ago.......It is an experience thing primarily and sure wish Curl could measure parts changes, but that is normally not the case........
I think that an amp that offers no feedback is far more accurate than one that doesn't. If your are seeking a very neutral amp that has the front end to support it, then I would strongly consider the Sim W-10's. I have heard that the Parasound is a good sounding amp, weather it has garnered the same International press as the Sim products is probably worth researching.I have had the pleasure of having a older W-5 in my system and was amazed at the sheer musicality that it offered.I also was shocked at the dynamics and the resolution it was capable of, it threw a soundstage that you could land the Enterprise on.The only concern is with the rest of your system, if it is on the hot side then you may not like what the Sim shows you.I hope that one day I may also own a powerhouse pair of monoblocks, since my speakers absorb quite readily. Hope this helps and good hunting-Dennis
Dennis - I have had and still own some NGF (no global feedback) amps, the CODA's. They are very sweet on the highs, but the JC-1's left them in the dust for detail, particularly with mods. The new Coda's are definitely better, because they are using better parts now (I heard them at CES). However, the Bass control of the JC-1's is hard to beat. NGF designs will never be capable of this. You really need NGF to get bass control and pristine, sweet highs are possible with it as well.
I think you maybe right on the bass control but the Sim would take the cake in detail and resolution.All the reviews by the press indicate that this is the most natural sounding amp.I know that these amps have been compared to 20 to 30,000 dollar Lamns and competed very well.As far as the Parasound is concerned, I don't have any experience with them.I did hear my friends Sim w-5 limited edition and it set a new standard for transistor amps as well as tubes. It had the liquidity of tubes and the slam and resolution of solid state.I think that it would be a horse race between the Parasound and the sim, however, the winner would probably be chosen according to ones personnel priorities( bass,detail,dynamics,resolution.That is was makes us all so special-Dennis
I would reactualize Drhst20’s question to Mr Crump - is it OK to turn the JC1 on/off daily, depending on listen or not listen? Does such a way of using could be harmful in any way for JC1’s status (in terms of, say, durability or stability of certain parts/circuits)? You Mr Crump keep your own JC1s “on” all the time. What is the purpose? Shortened warm-up period only, or maybe something else - for instance, preserving durability of inner circuits via avoiding so-called “cold start” occurence too frequently?

Stand-by option not being provided with JC1, unlike many similar big powerful amps such as Krell, Pass or many others, which are supplied with power-on breakers on rear panel (JC1 has not such breaker), supposed to be switched “on” all the time, except in cases of longer inactivity. Does it mean that JC1 is somehow “more resistant” to neccessity being “stand-by” while not “on”, compared to other heavyweights?

Generally speaking, what’s the reason for keeping power amps “stand by” while not “on”? Most manufacturers strogly recommend that in owner manuals (mentioned Krell and Pass Labs). Of course, we all know stand-by position keeps circuits ready for quick turning into amp’s full potential, shorting warming-up to only half an hour or so. But, I would consider that like minor benefit, IMHO.

My major dilema is, actually, does “stand-up” instead “off“ contributes longevity/stability/lifespan of amplifier? Vice versa - does “off” after “on” affects negatively some of amplifier’s parts/circuits??? Highly appreciate comments, due to frequent power failurs in my place.

Zoran, Macedonia
Another point,

Is it truth that JC1's retail price goes up to 7000USD per pair? I saw something like that on htguide forum.
If so - very dissapointing...
Yes, it is true.
I called a couple of dealers, and they confirmed it.
Wonder if there are any parts or circuit changes to justify the $1,000 increase?
Hi Dalton

I got opposite info from another forum. A dealer guarantee NOTHING has been changed with price. Tons of JC1s for 6000k pair...
The pricing of the JC-1 will go from 6K/pr to 7K/pr effective 5-1-05 due to increased parts costs.....

Bob Crump
CTC Builders
So if the Nichicon Caps are the result of the long break-in of the JC1, what can be used the has a shorter break-in time of same quality and cost? go smaller and have additional ones?
Lenght of breaking-in proccess should be not the crucial item. Why so much energy invested in week or two more or less waiting for optimisation? Final outcome is the issue, IMO. I love JC1 because of the final outcome performance (not owner yet, but will be one day if God say so...).
The sorry facts regarding the JC-1 is that they don't sound good unless you have 1200 - 1400 hours of play time on them. I heard a pair last year and frankly was underwelmed to say the least. They had a total of about 200 hours.
I would hope they sound great after 1400 hours, but me ( living in Australia) I am not going buy something I don't like the sound of, on the promise that it will dramtically change after 60 -90 days. If there was a money back guarantee - perhaps. I checked with the dealer today and the amps still only have 300 hours on them and they much prefer the W-5's. They thought I was mad stating that the designer asks you to put 90 days straight for it to sound decent.
To me Parasound should change the caps so anyone can hear 90% of what the amp is capable of after 200 hours of so.

Anyway I have given up on the JC-1 and will listen to a Pass X350.5 next week.

Anyway, my rant is over.
Uh oh. Ah...I hate to tell you this, but the Pass needs 2,000 hours to sound good.
I agree with Audioengr's comments about global feedback vs no global feedback. That is, the amps with global feedback will typically produce more "slam" and tighter bass than the designs that lack global feedback. Part of this has to do with the amps having global feedback having a lower effective output impedance. The drawback to this is that most amps with global feedback will lose midrange liquidity and tend to sound "closed in", "less spacious" and lack separation of notes in terms of midrange and high frequency response. The more global feedback that is used, the more noticeable this becomes.

This is why i've said that Pass amps ( new and old ) sound very nice but lack bass definition and oomph. Even though the newer X series have massive power supplies and great current capacity in the output stage, their circuit design i.e. non-global feedback and slightly higher output impedance is what limits their bass performance.

Too bad we can't get someone like Curl and Pass to work together on designing an amp and then have someone build it with good quality parts. I think that both of these guys are capable of stunning work and the end result would be a pretty fabulous product.

Sim Audio? Never heard any of it. Read some very nice things about their products, but nothing earth-shattering.

MBL 101's??? Good luck. Finding amps that are both good enough sounding and powerful enough to really throttle them as needed may be a life-long task. I wish you all the best and hope you enjoy the journey : ) Sean

What was the audition of Pass Labs X 350.5 like? Being underwhelmed of Halo JC1 performance after shorter break-in, you announced turning to Pass. I am deadly curious to know on first impressions!

Can anyone compare JC1 vs new Pass X 350.5?


Zoran, Macedonia
I am picking the Pass X350.5 up tommorrow and will have it over the weekend.
I will give an update after that
Yes, curious minds would like to know! I have been wondering how these two "Super Amps" would match up.

Also, after reading (3) seperate rave reviews, from (3) totally different types of reviewers/mags on the McCormack DNA500, I can't BELIEVE no one out there hasn't compared IT to either of these amps... (oh yes, I've posted the question)
I have posted the question too, Denf, but with NO RESPONSES whatsoever! I do not understand that either.
I would also like to know how Henry Ho's H2O ICE signature monoblocks compare to the above named amps?
Daltonlanny! Looks like it's up to one of us to buy the DNA500 (or H2o mono's) and find out for ourselves, eh?

Now, if someone will just loan us each $7k or so large...
Hey anyone out there, can Denf or myself borrow about 7 grand?? Pretty please? I promise we will pay it back sometime in our lifetimes! lol.
Denf, Zormi. For what it is worth I have now listended to the Pass X350.5's, JC1's one more time, bryston 7bsst and the cj premier 350.

In my system, the cj prem 350 sounds overall the best. It has the tightest (jc1 was pretty tight as well) and most natural bass out of all of the amps. the bass with the pass was just a little loose. mofsets vs bipolar??. The high end has a degree of dynamic top to bottom life that the others don't have. Musically they are the most satisfying.

The Pass X350.5 sounds good, but in my system the bass was a little overwelming and seemed not to have the speed in the top end the cj has.

Bryston sounded very controlled, but lacking a little dynamic life and extension in the high's.

JC-1's sounded a bit gray and lacking in dynamics unless you really cranked up the volume. Micro dynamics were not as good as the Pass of cj. My personal opinion is that sound wise it was on par with the Rotel 1090, which for its price sounded great.

anyway, I am buying the cj prem350 to mate with my Vienna mahlers.
Thanx Downunder,

Your judgement into such a strong competition have not been easy job obviously...
One of major advantages of Halo JC1 should be very affordable price, recently raised, unfortunately (plus recovered USD vs Euro). Almost reaching territory of giants like Pass, Krell FPB, Mac..., Parasound Halo JC1 is still OK, but stops being ultimate choice. That's why I gave up from upgrade my Halo A21 to JC1.
BDW, damn right that Rotel RB-1090 fights very well for money.

Congrats for choice. Enjoy.
Zormi. I really wanted to like the JC-1's. The bass was definately better the second time round, but it had no life in the upper mids and top end. Just plain boring. I really think parasound need to change there caps as no one in their right mind can expect to wait 1200 hours for the amp to sound better.
The Mac 501's and Pass 350.5 sounded good after 50 hours, Krell 300cx was starting to sound better after 150 hours but still a little strident in the highs for my taste. cj after 120 hours, still improving. All these amps sounded at 95% plus at these hours, which is what high end hi fi should be like.

Interesting the low or no feedback designs ( prem 350, Pass 350.5, Sim W5) were to my ear the better sounding amps compared to their high feedback cousins like Parasound, Mac and Bryston. It was if the high feedback amps had a limiter on the expressiveness and natural tones in the upper mids/and treble. The high feedback amps had arguably the bigger bass thou. But it is top to bottom conherence and musicality that rule the day with my listening biases.
Downunder: I would not have expected the Pass amp to be a good match with your speakers. Most Pass amps are a little "round" sounding in the bass, albeit in a pleasant manner. The problem is that, when you combine it with speakers that lack damping, suffer from ringing and are round sounding to begin with, you've got WAY too much of a good thing. The Vienna's definitely fall into that category, at least in my opinion.

As to the high feedback amps sounding "closed in", this is what i predicted that the JC-1 would sound like after learning that it used gobs of negative feedback. While i was initially eager to hear this amp, after finding out more about the technical aspects of the design, i knew that i would not like it sonically. Somewhere in the archives, you'll find those comments, along with what i posted above. That is, high negative feedback designs tend to sound less liquid and sterile. They measure good on the bench, but simply don't sound "magical" or "musical".

As such, i don't doubt your results at all. In fact, a couple of them simply confirm previous observations that i've already made, all without hearing the gear or combo of gear in question.

There is one thing i'd like to add though. That is, you guys really need to check into using low impedance speaker cabling ( 20 ohms at MAX ) with amps of this calibre. The benefits with amps of "marginal" build quality are noticeable, but when you've got a real "powerhouse" of an amp using good quality parts, the benefits become even more apparent. That last level of "musical accuracy" i.e. "detailed notes that float in the air, dripping liquidity and impact" become a reality. That's because the amp can finally "load up" into the speakers and the power transfer characteristics are improved. Better power transfer characteristics means increased control, reduced reflections and improved sonics.

In my Dad's system, i changed his preamp, power amp, DAC, modified his speakers, changed interconnects, etc... When i finally installed some low impedance speaker cabling, he told me that those speaker cables made more of a difference than all of the other changes combined. What he didn't seem to take into account was that the change in speaker cables simply allowed him to hear all the benefits of the upgrades that had already taken place, which his other speaker cables simply didn't let through. After all, the cables aren't doing anything magic, they are simply reducing losses in the system.

By minimizing the losses, you get to hear more of what the system is truly capable of. So long as you have a good system, you should like what you hear. If you don't have a good system, you'll get to hear just how bad certain aspects of the reproduction really are. Don't blame it on the low impedance speaker cable though, because it's not an active part of the reproductive chain. It's simply a conduit for the signal that already existed. Now you get to hear the system, warts and all. Sean