Sunfire Load Invariant Stereo Amplifier Amplifiers

Load Invariant Stereo Amplifier

User Reviews (14)

Showing 1-10 of 14  
wayne nielson   AudioPhile [Feb 25, 2002]
Strength:

More power and dynamics than most will ever need.

Weakness:

No power switch.

The Sunfire Stereo amp is in use with: Sony TAE-9000es pre-amp. Martin-logan reQuest fronts. Sony TAN-220 rear channel amp. Difinitive Technologies BP2X surround speakers Sony CDP-XA20es CD player. Acoustic Research ARS300 Sunfire powered subwoofer. Results: Using "small hall" or "live room" on the Sony pre-amp, the Sunfire could play transients to lifelike levels. Any of Brian Setzer Orchestra albums became startling with realistic attack and decay. The word phrase "dynamic range" now can be uttered. Forget SACD, get all of the sound out of the regular cd''s. This is the BEST front end amp in the world, period

Similar Products Used: Soundcraftsmen 5002, class H
OVERALL
RATING
5
VALUE
RATING
5
C.J.   an Audiophile [Mar 15, 1999]

In my system:· Theta Data Basic II
· Adcom GDA 600
· Sonic Frontiers Line I
· Sunfire Load Invariant Amp (voltage outputs)
· Martin Logan Sequels I
· Sunfire Sub. Mark II
· Cables: various

The amp. has acquitted itself has a superbly natural piece of gear, and outperformed far more expensive amplifiers before finding a place in my home. I have been a musician and devoted listener for 36 years, and have a very good idea of how things sound given certain instruments and the recording acoustic. Everything through the Sunfire sounds immanently right (octave to octave balance, attack, decay, harmonics, soundstage, imaging, dynamics, etc ). As a matter of fact, I have heard my system outgun those costing 10 times as much.

Understanding that:
· The state of audio is edging ever closer to that of absolute reproduction
· The law of diminishing returns rears its ugly head logarithmically with (roughly) each doubling in cost
· There are those (manufacturers, sales people, and consumers alike) who foist ill-gotten opinions that become popular in certain circles with no basis in fact whatsoever. Given that, many sales people will be slighted about some of their own equipment and give you the wrong advice because of it
· Many audio shops do not have the wherewithal to properly setup and display all of their equipment, thereby, compromising performance
· The art of audio reproduction is the ability of putting together a complementary series of components that surpasses the sum of its parts
· A well chosen (using Stereophile as a point of reference) "Class B" system can outperform those based on poorly chosen "Class A" equipment.

It stands to reason that one should let a certain in-depth knowledge to the fundamentals of audio reproduction , open mindedness, curiosity, the ability to experiment, and reproducible experience (not tongue waging) over time be your guide.

With that, the Sunfire stands an overachiever in its price range; bearing witness to its review in the Absolute Sound and that it has sounded stellar in every system that I have heard it in. To that end, I would certainly buy another one, and recommend it to those looking to purchase anything near or greater than its asking price.


OVERALL
RATING
5
VALUE
RATING
Roger W. Stevens WA3FLE   an Audio Enthusiast [Sep 22, 1998]

I had to do this--I had to buy a godawful powerful amplifier to drive my PSB Goldi's in their far-field monitoring application in my 26'X 26' home-based studio, and my Hafler DH 500 (bless its heart) just could not quite deliver the goods. Always sounded great, mind you (to me, anyway), but would cut out due to its over-temperature protection circuit after 10 minutes of 105+ dB SPL (at one meter, average program material). Drove me nuts; I chased this problem for months--see my PSB Goldi review(s)--and finally decided it was a natural physical phenomenon: according to the Stereophile review (I don't measure these things myself), the Goldi's impedance drops to 2.87 ohms if I recall correctly at some fairly low-ish frequency, and that was pulling more power than the DH 500 could comfortably deliver. So be it.
Thus the search was on. Search--I watched an as-described mint Sunfire go without making reserve up on eBay and emailed the guy and offered him $50 over that reserve (after asking him what it was during bidding), if he would ship it from NC to PA. He went for it and then I had to decide if it was the right move. Sometimes the deal can get ahead of you.

Not this time. Problem solved. No more cutout, no noise, no graininess, no weak-kneed bass, no overly prominent nor recalcitrant mids or treble, and no overheating. In fact, it is the coolest-running amp I own, including (most especially) 12 wpc 6BQ5 integrateds by EICO and Dynaco. And at 2 ohms, it is rated at 1200 wpc! That's a factor of one hundred, or 20 dB. My hat is off to Bob Carver and this remarkable engineering accomplishment.

As a matter of note (no pun intended), I also have and love an Audio Note OTO SE Phono, so my ears are accustomed to many different approaches, and I did a lot of research (or rather pre-search) about this amp. I read every review up on Sunfire's website, and was impressed by those by The Absolute Sound, as mentioned in another review. And at barely 4 digits used, it was too good to not to try.

And try it I did. And glad I did, too. A local Sunfire dealer actually somewhat pooh-poohed the amp, though they are more of a car audio and home theater outlet and don't even stock it--their comment was that Bob Carver is a hell of an engineer, but not a great marketeer. What, is that supposed to deter me? They tried to interest me in a traded-in Parasound 2200 Mk II. for less than a grand, until I told them I had already sent the guy the money for the Sunfire. Dealers--they sell what they have (don't you love 'em?).

The balanced XLR inputs and the unbalanced Lab Direct and Normal RCA inputs as well as the Voltage and Current outputs make for an interesting tweak-friendly product--almost like having four different amplifiers in one. I've been swapping around--right now I have the Normal inputs and the Current outputs running in a BiWired configuration to the Goldi's. The Voltage outputs are noticeably faster and cleaner, but on some older CD's in particular maybe a little too fast on top, especially with the Lab Direct inputs, while the Current outputs at first seemed a bit prominent in the mids, but after further listening seem to just have a touch more bloom and a tad less sparkle. The Normal inputs allow me to sleep better, as I use an older tube preamp, as the amp does not have an on/off switch, if your preamp thumps when it comes on, look out for your speakers. It would be nice if the amp had an input signal detector and automatic turn-on/shutdown feature, but it's cool the way it is, as long as your preamp behaves.

The preamp I use is a factory version--not a user upgrade--of the Conrad Johnson PV2aR with hand-selected tubes, and it makes a great combination along with the Sunfire. It just seems that this amp loves a tube preamp, but I haven't tried it with, say my AGI 511A, to see how that works.

This is the kind of amp that sits on its factory-supplied "crystal" base under the operating console desk always at the ready, and just does its job day in and day out except that every time you turn it on and play something, you think, "Ah--that's the sound I was looking for". It's really hard to imagine another amp doing so much so right for so little money, comparatively speaking.

I only give 5 stars in my reviews because I try to only buy "5 Star" equipment.
And happily, that's the case here.

Please be an organ and tissue donor and tell your family about your intentions.

OVERALL
RATING
5
VALUE
RATING
Robert   Audio Enthusiast [Mar 04, 2001]
Strength:

Smooth Treble, natural harmonic balance, spacious sounding

Weakness:

background hum is sometimes audible

I had to respond to some of the erroneous statements in some of the reviews here. None of the Sunfire amps are Class D switching amplifiers. The Amplifier circuit is a rather conventional Class AB type; the are no switching devices in the audio amplifier channels. What makes these amps unique is their power supplies. The Power Supply IS a switching type supply but it is unique in that it tracks along with the music signal. The supply is essentially a regulated power supply but instead of using an immovable static voltage reference(almost impossible to achieve), it uses the music signal itself. The advantage to this is that the output transistors of the amplifier do not have to dissipate the heat produced by having fixed power supply rails that are significantly greater than the average signal level. At idle the output transistors see only about 8.5 volts across them. As the music signal increases, the supply rails continuously track the signal. At full power the supply rails approach 120 volts.As a result, the Sunfire amps have no heat dissipation devices and yet still run cool.Another advantage to thse amps is that they cope extremely well with low impedance loads. The Sunfire amp will double its wattage into 4 ohms, double it again into 2 ohms, and if your circuit breaker can stand it double it again into one ohm.
What I like about this amp is that Bob Carver took a lot of time to voice this amp according to his musical tastes. It has the least fatigueing treble of any amp I've heard since the Aragon2002. Ironically, it is also quite detailed without becoming edgy. The Bass isn't as huge as a Krell but its very nice. The amp gets the midrange very right and after all, that's where most of the music lives.
This amp can be tweaked if you know what you are doing. Some benefits can be made by improving the parts quality; Do not try and alter the circuits themselves- it took a very bright man 5 years to perfect them. Do not apply ferrite beads to the power supply grounds- you want a low impedance ground at RF frequencies. Try litz or some other finely stranded ground wire. Try lowZ electrolytic caps with .01 uf polypropylene bypasses. Try replacing the 150pf, the 470pf and the two 750pf ceramic capacitors on each channel near the input jacks with polystyrene or polypropylene types. Note this will change the apparent soundstage from midhall to close to front row.

Similar Products Used: Adcom GFA555, Audire, Dyna400,etc
OVERALL
RATING
4
VALUE
RATING
5
Dave   Audio Enthusiast [Oct 18, 2001]
Strength:

as everyone is saying: smooth presentation, not overly huge or heavy but with ample power reserves and good soundstaging. It's also an attractive piece of equipment with a better than usual array of input and output options, including balanced XLRs, and two sets of phono inputs, plus two sets of five-way binding posts for outputs.

Weakness:

if choosing the current output, highs may be perceived as slightly overly tamed

I must say that this amp is a pretty unconventional one when compared to its competition-- higher-end Parasounds, Brystons, used Krell, higher-end Rotels, etc.

Although the cabinet is only somewhat smaller than most amps of this power rating (300wpc@8ohms, 600@4, 1200@2!), its weight is the shocker-- only 42lbs! There are no massive heatsinks, and not even any cooling vents on the top of its black, brushed aluminum case. There are cooling vents to the sides and bottom, however.

When running for at least shorter periods of time, this amp runs amazingly cool (cooler than some preamps!), no matter what volume level is being played. The meter in front also doesn't vary much at all, and I presume it measures the power reserves in the tracking downconverter in joules. It certainly doesn't track the audio signal whatsoever. Based on all this I can see how many higher-end audiophiles would be very skeptical of this highly unconventional design.

Input and output options are quite varied, and should satisfy just about any setup. inputs include two sets of unbalanced phonos (lab-direct, and normal), and a set of balanced XLRs. Output is made via two sets of five-way gold plated binding posts. One set is for the voltage output (standard), one for the current output (for use with electrostatics, or for imparting a 'tube' like sound to your upper section mids/tweets in a biwire configuration).

On to the sound: Although I a still trying to sort this out, my findings do confirm that output via the current source does tame high frequency harshness tremendously. My amplification/speaker chain consists of an Adcom GFP-750 preamp running balanced to the Sunfire, which is biwired to a pair of NHT 2.9s. Voltage source for the woofers, current source to the mid/tweeter section.

Bass, while strong before, is possibly even more stupendous now. This amp can drive these speakers to very high sound levels without apparent strain. This, and the NHTs are known for being very power-hungry but with potent bass capability.

Part of this newfound bass, however, may be emerging at least partially because the high frequency output has been attenuated somewhat using the current output mode. The NHTs could sound somewhat tipped up, and even edgy and bright on certain source material. Now the tonal balance is much more to the laid-back side, and the sound is overall somewhat darker. Detail does not seem to be lost too much, but is certainly less prominent.

I could easily see how other users who have speakers that already err towards the laid-back side (Vandersteens, etc.) would think that the sound of this amp would be almost muffled. After all, it tamed the NHTs!

But then again, my old THX ultra amp was almost certainly on the bright side in terms of presentation.

Bass control of this amp, while not noticeably tighter or better than my previous amp, is certainly acceptable, and may indeed be better at higher volume levels. It has been said earlier that this does not seem like a 300w amp, and I have to agree with some reservations. It does not seem like it at lower volume levels, but I can fully believe it at high volume levels. It never loses control of the woofers, even at room-shaking levels. It's very disconcerting to hear and feel this power coming out of my speakers and feeling no heat whatsoever coming out of the amp's cabinet.

Overall: bass is juicy, plump, with possibly a slight bit of overhang but very good control at higher volume levels;
highs: presentation is relaxed, softened, and is best used in current output mode if the user's speakers are already on the bright side. An additionally heavily damped room could push this condition over the edge into unacceptability.

I got mine used on ebay for $1000, which I think is a fine value for a product of this quality. But at the SRP of $2500? Then I have to think again, because for that money you can get Parasound's HCA-2500A, Bryston's highly regarded 4b-ST, and a number of very high quality amps from other manufacturers. The competition is very tough at this price point, and a user should pre-audition all equipment in their home and think very hard about which amp would serve them and their system the best.

Similar Products Used: Kenwood KM-Z1 THX Ultra amp, various
OVERALL
RATING
4
VALUE
RATING
5
C.J.   an Audiophile [Mar 15, 1999]

In my system:· Theta Data Basic II
· Adcom GDA 600
· Sonic Frontiers Line I
· Sunfire Load Invariant Amp (voltage outputs)
· Martin Logan Sequels I
· Sunfire Sub. Mark II
· Cables: various

The amp. has acquitted itself has a superbly natural piece of gear, and outperformed far more expensive amplifiers before finding a place in my home. I have been a musician and devoted listener for 36 years, and have a very good idea of how things sound given certain instruments and the recording acoustic. Everything through the Sunfire sounds immanently right (octave to octave balance, attack, decay, harmonics, soundstage, imaging, dynamics, etc ). As a matter of fact, I have heard my system outgun those costing 10 times as much.

Understanding that:
· The state of audio is edging ever closer to that of absolute reproduction
· The law of diminishing returns rears its ugly head logarithmically with (roughly) each doubling in cost
· There are those (manufacturers, sales people, and consumers alike) who foist ill-gotten opinions that become popular in certain circles with no basis in fact whatsoever. Given that, many sales people will be slighted about some of their own equipment and give you the wrong advice because of it
· Many audio shops do not have the wherewithal to properly setup and display all of their equipment, thereby, compromising performance
· The art of audio reproduction is the ability of putting together a complementary series of components that surpasses the sum of its parts
· A well chosen (using Stereophile as a point of reference) "Class B" system can outperform those based on poorly chosen "Class A" equipment.

It stands to reason that one should let a certain in-depth knowledge to the fundamentals of audio reproduction , open mindedness, curiosity, the ability to experiment, and reproducible experience (not tongue waging) over time be your guide.

With that, the Sunfire stands an overachiever in its price range; bearing witness to its review in the Absolute Sound and that it has sounded stellar in every system that I have heard it in. To that end, I would certainly buy another one, and recommend it to those looking to purchase anything near or greater than its asking price.


OVERALL
RATING
5
VALUE
RATING
Jfrey   an Audio Enthusiast [Jul 01, 1999]

I read about the sunfire and found the articles interesting. I have allways liked the Carver products and feel that they have been given a bad rap. I finally found the Sunfire amp at a going out of business sale and got one at a bargain and what a buy it was. I have heard systems that cost many times hat the Sunfire cost and can say that I don't believe that it can be beaten atleast at an affordable price. I have some Magnepans that sing with the power.

OVERALL
RATING
5
VALUE
RATING
Pat   an Audio Enthusiast [Jul 05, 1999]

This amplifier has really opened my ears to "realism" in my home. I really excels in the midrange and higher frequencies. Cymabals and female vocals have never sounded so real. Although 300wpc may be hard to believe, it's the sound that I like.This drives my Mirage M3si's , closest to tubes that I have had.

Also had the Parasound, Adcom, Rotel at home for a face off- All sounded very different(to my surprise), and the Sunfire was the champ-

OVERALL
RATING
5
VALUE
RATING
jeff   an Audio Enthusiast [Aug 17, 1999]

I had the Sunfire in-house for about a week. It replaced my previous trial products Adcom 5400, 5500, and B&K 4420. Adcom's had no detail whatsoever. B&K sounded pretty good, but was lacking bass on my system. My initial listening to the Sunfire had me packing up the B&K immediately (something I sort of regret now). After 2 days, though, I tired very much of the Sunfire sound. Yes, it would play very loud, and if thats all you're after, go for it. I found everything but the bass to be muffled somehow. My speakers aren't awesome (15 year old Polk RT-12a's) but they remained a constant in my listenening tests, so I really can't blame them. For the price of this unit, you get alot of wattage, end of story. By the way, the reason I'm even looking is because my 15 year old Carver M-250 sadly died on me, so I've got nothing against Bob Carver equipment.

OVERALL
RATING
3
VALUE
RATING
MR.Purple   an Audio Enthusiast [Mar 02, 1999]

Im sorry about my past negative review of the sunfire. You see I work for Pass Labs, well I did, before they went
belly up. We were desperate to get rid of all those crappy
amps.So we tried to dethrone all the best amplifier makers
by writting ubsurd reviews about all there best products.
Products like Sunfire wich by the way I own and LOVE. I
felt like such a little bitc?!" writting in my past review
about how I wished for a restraining order agianst the
Sunfire amp. I know,I know that was such a stupid and
childish thing to write.Anyway I hope I didnt persuade
anybody into not buying the Sunfire. It really is one of
the best amps ever made(Way better than the crap we made at
Pass LAB).Happy listening!

My current front end
Sunfire Theater Grand
Sunfire Cinema Grand
Sunfire Signature Amp

OVERALL
RATING
5
VALUE
RATING
Showing 1-10 of 14  

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