As someone who’s been involved in the engineering industry for may years, it’s hardly surprising that I’ve developed the annoying habit of wanting to tinker under the hood. Fortunately I know my limitations, and in most cases I manage to control my primitive urges to just ‘taking a peek’. However, in doing so I often find myself frustrated by what I see, particularly with high-end audio equipment. It’s frustrating to see equipment with a fairly hefty price tag assembled from components that don’t seem worthy of a place in such an expensive piece. It always leaves me wondering how the component might have sounded had better parts been used.
Well it seems that I’m not alone in my assumptions and a regular old cottage industry has appeared overnight, with the lofty ambition of modifying audio components and stretching their performance to higher levels.
For a year or more I’ve been going through a process of rebuilding my system around a set of Magnepan 3.6R’s. The poor Maggie’s haven’t escaped the knife either, internal rewire, custom XO’s and custom stands are projects I’ve undertaken and are documented elsewhere on this website. But it isn’t the Magnepan rework that I wanted to talk about here, the focus of my attention is on one of the “new breed” of digital amps to hit the market, the Carver Pro ZR1600.
The Carver Pro ZR1600 is a class T (Tripath) digital amp, and according to Carver themselves, the amp “has impressed audiences and system integrators for years and has introduced state of the art technology (in the new ZR Series amplifiers) utilizing Tripath™ Digital Power Processing™” Clearly, digital amp technology is relatively new to the audiophile community but has been around in the proaudio world for quite a while.
The name Carver is generally associated with legendary designer Bob Carver, indeed the name is his but the rights to manufacture this product and other pro-audio products have been sold to a non-associated company based out of Portland Oregon and operating as ‘Carver Professional’. The long and short of it is, regardless of what you think of Bob Carver and his products, this amp bears his name and nothing else.
Spending time at the Carver Pro website (www.carverpro.com) you’ll see that the marketing focus is on power and flexibility of use, with a smidgen of robustness thrown in for good measure. Given that the ZR is designed primarily for pro-audio use, the area of focus seems appropriate and more meaningful to its potential owners than ultimate sound quality.
The amp retails for a touch less than $1200, yet I was able to procure a pair of these for $725 each.
Now I’m not generally the gullible type, and I take reviews for what they are – one person’s opinion delivered with as much entertainment factor as the author can muster. However, I treat banter on the popular audio websites like AudiogoN, AudioCircle and the Asylum differently. I look for trends in opinion and I follow certain individuals who over time strike me as being knowledgeable and having a certain amount of common sense.
And so it came to be that sufficient positive comment on the audio forums drew me to take my chances with the Carver ZR and to see what the attractive power and efficiency specification could do for my power-hungry Magnepan 3.6R’s.
Based on this fairly consistent ‘forum-chatter’, I’d pretty much decided from the outset that one of the pair of Carvers would need to be modified to deliver the level of performance that I was looking for. Folklore had it that out of the box they were good for the price, but modified they were ‘giant killers’ and could compete with and beat such esteemed products as the Pass X600’s and Parasound JC1’s.
When the amps arrived I gave them an arbitrary period of break-in, perhaps 100 hours or so, then tried various configurations with the Magnepan’s, including monoblock, vertical bi-amp and as single stereo amps.
I was pleased in a sense that a single amp in stereo mode appeared to provide the same degree of control and sonic performance as using two amps as 1200w monoblocks. Rated at 600w into the 4-ohm speaker load, the single Carver seemed to have a fair grip on the 3.6R’s with a fairly taught and extended bottom end. The midrange was surprisingly liquid for a solid-state amp; the highs seemed rolled-off however and perhaps a bit dull and lifeless. On hand at the time was a pair of older Perreaux power amps that I’d used quite successfully bi-amped with the 3.6’s and a Krell FPB200.
And so at that stage in the proceedings the initial research that had lead me to the purchasing decision seemed to be quite sound. They came in at right around the performance level I’d expected, for $725 each, a fairly respectable sounding amp.
When the amps arrived (back in Fall 2004) I’d already researched my upgrade options and there were only two companies at the time listing ZR modifications on their respective websites, Empirical Audio (www.empiricalaudio.com and Reference Audio Mods (www.referenceaudiomods.com).
Having read reports online from individuals who’d had Carver Pro amps modified by both parties, and having spent time studying information at the Empirical and RAM websites, I finally decided to try my luck with Steve Nugent at Empirical Audio.
To borrow a quote from Steve’s website: “The Carver ZR1600 is a very powerful amp which can drive virtually any load. It is particularly good for driving electrostatics and magnetic planar speakers, however the stock amp lacks both dynamics in the mid/high-frequencies, is limited in high-frequency extension and lacks finesse. In it’s stock form, the fan is excessively noisy and the only inputs are balanced XLR and phone jacks.
The binding posts are unnacceptable(sic) for anything except bare-wire termination. Our mods correct all of the above deficiencies. The amp has slam in spades once the mods are in and the HF extension competes with the best amps on the market. It has that “sparkle” of magic that happens only in the very best amps. The detail rendering is unrivalled by any amp we have heard.”
That’s quite an enticing statement, one that might have you salivating in anticipation or running for cover, depending on your mood at the time.
The list of modifications was equally impressive, and again, taking the current list from Steve’s website, the amplifier mods include:
- New quiet Papst Fan
- New OFC copper RCA input jacks – Vampirewire
- New perfect crystal silver input wiring from the RCA’s with expanded Teflon insulation
- Replace final capacitor filter/resonators
- Replace coupling capacitors with Multicap polystyrenes
- Replace coupling resistors with Caddock
- Replace all op-amps with low-noise, high-performance Correct ground-loops
- Improve power decoupling
- Add Black Gate and large Nichicon caps to power supplies
- Delete output board
- Replace rectifiers with HEXFRED’s
- Redesign all of the op-amp circuitry and adjust the gain
- Add power wiring harnesses
- Replace primary output inductor with handmade low-loss versions
- Replace secondary power output inductors with handmade air-core versions
- Add low-inductance output signal wiring harnesses
- Replace binding posts with Superior Electric hex posts
- Replace series power resistors with low-inductance Caddock
- Replace op-amp filters with polystyrenes
- Tuning of the output filters to minimize RF output (stock amp typically has 5-9 Volts P-P RF energy)
The price that I agreed to pay Steve for this extensive work was $1600.
However, there was a misunderstanding on one aspect of the mod specification, resulting in the need for two trips via FedEx Express to Steve’s location, so the final bill for the modification stage of the project was almost $2300 with shipping costs.
This is what I found: The stock amps have pro-audio binding posts that do not accept spades without the use of an adapter. When the amp arrived back I was disappointed to find that the new binding posts Steve had fitted would not accept two sets of spades. I was using two runs of speaker wire and needed to pair-up two sets of spades on the amp end, but the small binding post screws wouldn’t open far enough to accept both spades. So I had to open up the amp and remove the posts and replace them with a set of Cardas posts that I had on hand for a pending cross-over modification. So two hours later I was finally ready to give the amp a spin.
The amp powered up with the blackest of black backgrounds, in fact, no sound emerged from my system at all, and after an hour of checking through the obvious, I finally called Steve.
Steve’s website wasn’t as clear and explicit as it is now and I’d seen no mention of the balanced circuitry being removed as part of the modification. So imagine my surprise when Steve informed me that the modified amp would now only work in single-ended mode and that despite the XLR sockets being physically present, the balanced operation was defunct. Being the balanced kinda guy that I am, I decided that I couldn’t live with this limitation, so the amp was promptly re-packed and shipped back so that Steve could restore balanced operation. Steve charged around $400 to restore the balanced circuitry and tweak it to the standard required by the upgrade.
I received an email from Steve on completion of the mods and just prior to the amp being shipped back to me the second time. He expressed his satisfaction over the performance, even with minimal burn-in time. It was ‘better in many respects than his ‘Turbo-Modified’ JC1 Monoblocks’, which were his reference amplifiers at that time (and I believe still are). So I was naturally quite excited and looking forward to hearing what this giant killer of an amplifier would sound like compared with the stock ZR1600 that I still had on hand.
With around 300hrs on the modified amp it seemed to have settled in and some meaningful comparisons could be made.
My first minor niggle was that the Papst silent running fan that Steve had fitted didn’t seem any more ‘silent running’ than the original, it could be heard churning away inside the chassis from the TV room 20′ away. I’d disabled the fan in the stock unit, since the case never seemed to get even lukewarm to the touch. The modified amp however was different, the case was quite hot and I wasn’t about to disconnect the fan and have my $3k investment go up in smoke!
Sonically, after many hours of critical evaluation, I have to say that the modified amp was a disappointment.
Maybe I was the victim of hype and my expectations were set too high, but I think not. The main weakness of the stock amp was its lack of extension in the higher frequencies, and the modified amps appeared little or no better than the stock amp in this regard. I don’t want to be accused of semantics, but there is a difference between HF roll-off and a lack of HF extension. An amp (or any component) can be rolled off and still be extended. Output might be several decibels down at the frequency extreme but there can still be sufficient energy to give the music the air and sparkle that comes from extended HF. Both stock and modified Carver in my system lacked extension and were unacceptably rolled-off. The result was a rather dull and lifeless presentation above perhaps 7-10khz. Listening to my usual reference discs, for example the Ali Farke Toure / Ry Cooder CD ‘Talking Timbuktu’, the attack and impact was present through the upper midrange and into the 4-6 khz region, but the subtle spatial information and ambient cues that reside in the higher frequency range, were altogether missing.
I have a number of older Jazz recordings, some of which are quite well recorded in certain ways but are generally a little too bright. Both stock and modified Carver amps seemed to deliver a pleasing presentation initially, by taming a little of the treble excess and removing some of the harshness from brass instruments that had come close to falling into the ‘glare’ category with the Krell. Initially, this seemed attractive, but after a while, I sensed that it was more than just a little HF ‘bite’ that was missing.
The midrange/upper midrange of both stock and modified amps is perhaps the one area where they perform with a fair degree of competence. In the modified unit there was a little more midrange presence and clarity, perhaps ‘focus’ is a better word. Where the stock unit sounded rich and tuneful but ever so slightly veiled, the modified unit provided a slightly clearer sound that just seemed to open the blinds a touch and allow a little more light into the room. Bass extension seemed slightly improved with the modified amp, but nothing more than subtly so. Both amps exhibited tight and tuneful bass, the modified unit unearthed tones and notes that were buried just a tad deeper down in the frequency range, but again, subtle at best.
My second big reservation, the first being the poor performance in the higher frequencies, came in the upper bass and lower midrange regions.
I find the best way to evaluate performance in this frequency region is to use material that has been recorded live. The excellent Eva Cassidy recording ‘Live at Blues Alley’ is the perfect CD to assess whether a component or system can retain and deliver the ‘live feel’ of a recording, with all of the ambience, low-level information, and dynamic impact intact. In the upper bass/lower midrange region, the music is either rendered as a poor facsimile of the original, without true to life impact, or it retains the impact, drive and essence of the original recording and gives the listener a sense of being present at a live event. The stock Carver performed quite poorly in this region and the modified unit only marginally better. Both suffered from a lack of weight and authority and appeared not to recreate the full dynamic impact through the upper bass and lower midrange. This is surprising given the power specification rating of the amps, but once again it tells us that paper specifications do not paint the full sonic picture.
I don’t care to dwell on the usual audiophile checks and balances at this point. If a component doesn’t deliver the essence of the music, with satisfactory weight and authority, who cares whether or not it’s a champion at imaging or soundstaging?
Overall, had I been in the market for a $1000 power amp, I may have been accepting, perhaps just slightly less than satisfied with the performance of the stock unit. However, with the modified unit costing close to $3,000 one must rightly set the expectation level higher, and in doing so one cannot help but be disappointed in the level of performance attained per dollar spent.
I’ve owned/demo’d amps in this price range that would clearly beat the modified Carver in a head-to-head. The little Belles 250i integrated, at $2995, was clearly a more musically refined performer, and though it didn’t match the Carver’s power rating on paper, I suspect it was every bit as able to handle a difficult 4 ohm load as the Carver.
My old CJ CAV 50 integrated amp at $2500 was clearly designed for a different application, but at $500 less than the modified Carver it delivered sweet music by the bucket load and had the benefit of a preamp too.
My old Krell KAV300i on the other hand, was just as disappointing as the Carver, perhaps even more so, with it’s lack of musicality through the midrange.
Let me try to make two important points in summary. First, my usual disclaimer is that this is provided from a point of reference that no one reading this has access to. It’s my system, my musical preferences/priorities and my ears.
Second, and even more subjective, be careful when considering modifications. Without a doubt, component modifications are the flavor of the month, but that doesn’t mean they’re going to work out well for everyone. I have absolute faith and trust in the integrity and skills of the people involved in the modifications to my amp. I trust implicitly the opinion of the modifier and have absolutely no qualms that what he described as being the expected benefit from the mods, and the positive results that he heard in his system post mods, were completely representative of the truth.
But for me, the exercise was fruitless and expensive to boot. In my opinion, this amp, with the modifications described, could not be considered alongside the best offerings from Krell or Pass Labs as various people had touted online. (including the owner of the company from whom I originally purchased them and who shall remain nameless).
Personally, I’ll be happier when this current trend of modifying perfectly good stock equipment blows over. For certain, there are some valid modifications that can be made to components, but buying a new component with the intention of modifying it from the outset, has left me with a slightly bitter taste.
I’m tired of reading comments from people suggesting that component A or component B is just average in stock form, but a ‘giant killer’ when modified. In the future, I’ll just go out and pay for the giant and feel much happier and more secure in the knowledge that my hard-earned money has been more wisely spent.
Rooze
Discover more from Audio Resurgence - High End Audio Reviews and Products
Subscribe to get the latest posts sent to your email.
