$200 rcvr beats $11k separates

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James Romeyn

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$200 rcvr beats $11k separates
« on: 14 Jun 2009, 05:29 am »
I had a $7500 James Bongiorno-designed Spread Spectrum Technologies (SST) Ambrosia preamp w/ phono.  For reference, more widely distributed preamps in a similar performance category to the Ambrosia are the 1st-edition $17k VTL 7.5 & Krell Evo (estimate $15k).  Bongiorno invented the dual-differential full-complementary circuit in most high-end pre & power amps. 

The Plinius SA-50 Mk 3 power amp from New Zealand is often considered to be their best (50W pure class A, circa 2001, $3500 MSRP).  A music author/pro audio engineer told me the $19k Swiss darTZeel is an ultra-refined version of this Plinius circuit.  Plinius abandoned their lower-power pure class A designs when the 50 was discontinued in favor of higher powered & higher cost amps.  I am familiar w/ their popular SA250 Mk 4 & prefer the 50.  The 50 was probably the best SS I ever owned (till this).

After Dr. Earl Geddes became one of my favorite audio gurus I read one of his many posts at DIY wherein he mentions he owned costly high end separates.  After auditioning a Pioneer VSX-D912 receiver (pure analog power amp stage, 6x 105Wrms rated only for 8 Ohms, $450 new MSRP circa 2003-4) & after the 912 passed his rigorous proprietary tests Earl parked his separates in the closest.  He wrote he could hear no difference. 

Pioneer labels the power amp section a "hybrid" because it is a simple classic discreet circuit design shrunk & compressed into pure analog chip form-absolutely no digital technology.  I later learn the magic of the design is tolerance & consistency in parts values multiples beyond what is possible in a discrete circuit.  Think of discrete parts hand picked to the highest tolerance, then multiply that tolerance.  (The only known potential downside is the chip's low current capacity compared to its discrete forbear, meaning no pure class A & 8 Ohm load rating only: the farther the speaker load falls below 8 Ohms the less compatible is the 912.)

The techs at DIY were so favorably impressed w/ Earl's sketchy details of his proprietary test criteria that several enthusiasticaly promoted Earl publishing the specifics so they could employ it.  This fact coupled w/ the estimated $200 used value convinced me I had nothing to loose by purchasing a 912 & reselling it if it sounded like poop.

After audition in stereo, expecting the 912 not to compete w/ the separates described above, the separates were sold.  The 912 is preferred.  A second 912 was purchased for backup.   

The ONLY pure analog input is labeled "DVD 7.1".  Yes, it actually has 7.1 pure analog preamp inputs & pre outs, combined w/ six power amp channels (in the 912 7.1 sources have the two discreet rear surround channels internally mixed down to mono).  IIRC only so-called "True HD" is capable of 7.1 discrete; the 912 predates True HD but Pioneer apparently saw 7.1 coming & accomodated it in the preamp stage.  Only the fewest recent movies are recorded in 7.1...HT rooms less than about 13' width are too narrow to benefit from two discrete rear surrounds.  Meaning the sum total effect of the mono rear surround is virtually nothing (two mono rear surrounds are employed in my dual-use room though they are wired for 7.1 upgrade later).     

I can't recommend the 912 highly enough.  My music sources are unimpeachable so that's not a limiting factor in the comparison.  I first compared the 912 as a 2-ch preamp to the Ambrosia & heard no difference.  That was nuts enough all by itself: k'ching, a few thousand dollars dropped into my pocket.  As a preamp, no sonic deficit was heard w/ the 912's SE inputs/outputs vs. the Ambrosia employed w/ SE in/balanced out to the Plinius (Ambrosia is of course fully balanced throughout).  The same interconnect was employed except for balanced Ambrosia preout vs. SE 912 preout. 

The 912 employed as an integrated amp was preferred over the Ambrosia/Plinius combo & over the 912 preamp/Plinius combo (more pure & transparent above the upper midrange in both cases).   

What can I say?  Take a $200 chance.  You might be surprised.  I'd put the 912 up against anything.  The 912 was later preferred over a Pass Labs Aleph power amp by myself & several others; Jolida Music Envoys probably were preferred & probably costly custom 300B monos were preferred.  But the 912 wasn't humiliated by either.  It's that good. 

The best tubes probably are more textured & palpable, but my Trinaural system provides more of those qualities using the "lowly" 912 anyway, so this is of minimal consequence to me. 

SS wise I think you'd have to move into something like the darTZeel & wouldn't be surprised if it kept pace w/ even that. 

Again, unless you are an audio boutique snob concerning cosmetics, the only caveats are:
1. The farther your load falls below 8 Ohms the less compatible is the 912.
2. Overall performance bloomed, esp in the bass, after removing the 49c permanent AC line cord, installing an IEC socket from PE & employing a line cord made following Stan Warren's recipe from decades ago (low cost high performance).

The only change performed at the time of the IEC socket retrofit was to treat w/ Caig Pro Gold the only visible fuses & sockets, being two internal 10A.  After installing the IEC socket I compared a $1.99 generic line cord to the Stan Warren recipe: huge upgrade by my ears.  I'll post instructions for cutting the hole for the IEC socket if interested.  The only other mod planned is to apply Dynamat, Black Hole or similar to the bottom chassis & top case; the top case especially is rather flimsy.

Only a sum total once did the 912 shut down for apparently being overdriven (recovered & played normally after a few minutes of cool down) while playing a Ray Kimber Iso Mic full orchestra SACD at live levels.   

Let us know your results if you try a 912.  My 2 kopacks.         
« Last Edit: 10 May 2011, 10:16 pm by James Romeyn »

hoxuanduc

Re: $200 rcvr beats $11k separates
« Reply #1 on: 16 Jun 2009, 06:08 am »
Very interesting...

What you're saying is the Pioneer sounds so good because it's basically a chip amplifier ala Gainclone (well, maybe more advanced and more features).

Current Pioneer receiver ads also tout "Hybrid Direct Energy" amplification.  I wonder if the same technology is used in the current line up as it was with the 912.  The 912s are kind of hard to find, even on eBay.

It would be interesting to check the VSX 919 @ BestBuy to see if it is comparable...


BTW, is the Stan Warren recipe public domain? If so, can you share it?

Thanks,

Duc


James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #2 on: 16 Jun 2009, 04:59 pm »
What you're saying is the Pioneer sounds so good because it's basically a chip amplifier ala Gainclone (well, maybe more advanced and more features).

I'm no engineer.  I don't know why I like the Pioneer or exactly why it sounds like it does.  I don't know if the same vintage Pioneer rcvrs w/ advertised "hybrid" technology sound the same within their lower power envelope (the 912 is the highest power "hybrid" of that vintage series; who knows, the lower power "hybrids" might sound better, as is the case sometimes w/ power amps of the same make/vintage/technology). 

I have read prior raves about "Gainclone" amps but do not know exactly what it is & certainly have no idea of any similarities between Gainclone & the 912.  If you are stating the 912 is a Gainclone, why?  Are you a tech?  Have you compared the schematics?  This is more than academic to me because I considered building a tweaked mono version of one channel of the 912 for my center Trinaural channel.  But upon reflection I bet a tweaked custom version of one 912 ch would sound no better than the rcvr.  If I upgrade the center it will be via Atma-Sphere OTL & nothing else.     

Quote
Current Pioneer receiver ads also tout "Hybrid Direct Energy" amplification.  I wonder if the same technology is used in the current line up as it was with the 912. 

Great question.  I have absolutely no idea on earth the answer & doubt anyone except a tech could know.  Of course there's always the proverbial audition/comparison as I described above. 

Quote
The 912s are kind of hard to find, even on eBay.

That's interesting that you write that.  Both times I searched on Ebay I found & purchased one right away, though someone else searching for a 912 similarly reported the 912 was hard to find.  I made sure my backup was on the way before making the post.

Quote
It would be interesting to check the VSX 919 @ BestBuy to see if it is comparable...

I agree.  From a personal standpoint, I've got two 912s & Pioneer electronics are extremely reliabile, meaning I have no need for a third reciever & I seriously doubt the newer models sound better.  Also, my music sources are of such a rare caliber that I'd take another persons report of similar performance w/ a grain of salt, w/ all due respect.  Other readers can draw their own conclusions. 

The only potential advantages of a newer reciever would be True HD, full 7.1 capability & higher quality DA performance.  For video I have no complaints about the 912's DA performance.   

For music: my CDP & strain gauge phono are in the top percentile in music performance.  The CDP analog stereo output goes into the pure analog Trinaural Processor, which via algebraic forumla in the analog domain creates a 3.1 output (center is NOT summed mono; best described as an analog version of Meridian's famed Ambisonic DSP).  The Trinaural goes to the 912 which powers three front speakers (the 912's sub output goes to a sub amp powering four subs per LeJeune/Geddes multi-sub criteria: quasi-X pattern, one sub out of phase, etc, etc.)  The above 3-ch pure analog processing was compared to the 912 digital processing employed to achieve the same result (synthesize 3.1 channels from a 2-ch source).  To say the Trinaural ate the 912's lunch then kicked it up & down the street while eating said lunch is a pretty good description of the result.  (I went back & forth several times because I was anxious to put even more money back into my pocket by selling the Trinaural.....absolutely no way on earth). 

In passing here, I'd say the two most significant things I've learned in audio in my whole life were:
1. LeJeune/Geddes multi-sub technology to flatten modes & achieve commercial space bass performance in a domestic space.
2. Trinaural makes stereo sound like a caricature/cardboardy & saves thousands of dollars in achieving better performance.

Probably listed in order of significance above. 

Quote
BTW, is the Stan Warren recipe public domain? If so, can you share it?

I have a 4-page document covering Stan's IC, speaker & AC line cords, plugs, jacks, etc, etc.  I can't just take items out to make it shorter because, well I just wouldn't know how to edit it down.  BTW, I worked long & hard to make sure the recipe is accurate; there are/were a lot of cobbed together wrong & incorrectly modified recipes. 

Four pages is too long to post here; probably best in the DIY forum as a sticky or?  PM me your email & I'll attach it to an email.  Please just give Stan the credit for the recipe & me credit for the archiving. 



 

rahimlee54

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Re: $200 rcvr beats $11k separates
« Reply #3 on: 16 Jun 2009, 05:06 pm »
where did you read all the stuff on Gedes, I am looking for some more stuff he has done.  Very interesting though.

Thanks
Jared

vman71

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Re: $200 rcvr beats $11k separates
« Reply #4 on: 16 Jun 2009, 05:09 pm »
I just tried to PM you with my email address so I can also get a copy of the Stan Warren recipe.  Can you PM me and I'll provide my email address.

I'm extremely fortunate to have 2 of Stan Warren's custom chip amps and they are so good.  I prefer his chip amp to both a Plinius amp and a Musical Design amp.  Both of these amps are outstanding but the chip amps are better in a number of ways.

Niteshade

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Re: $200 rcvr beats $11k separates
« Reply #5 on: 16 Jun 2009, 05:17 pm »
Jim,

What sonic attributes do you like about the Pioneer? With something like this, the preamp section is the most important part of the receiver. Receivers typically have a decent amp section, but it's the preamp that provides most of the voice. Chip amps are not bad for the most part. I bet one of these Pioneer amp modules would be twice as good with a high end preamp driving it.

Blair

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #6 on: 16 Jun 2009, 05:29 pm »
Jim,

What sonic attributes do you like about the Pioneer?


As mentioned above: the 912 pre stage matched the Ambrosia; as an integrated the 912 performance above the upper midrange was more transparent, musical, less hashy & less noisy vs. the Ambrosia pre/Plinius power combo.

Quote
With something like this, the preamp section is the most important part of the receiver. Receivers typically have a decent amp section, but it's the preamp that provides most of the voice. Chip amps are not bad for the most part.

Audiophile generalizations should be kept from this discussion because they are irrelevent, w/ all due respect.  This is a direct AB against a world class preamp & a  very good power amp. 

Quote
I bet one of these Pioneer amp modules would be twice as good with a high end preamp driving it.

I'm not sure what part of the Ambrosia you are implying is not a high-end preamp?  You are highly mistaken, again, w/ all due respect.  Unless you have some personal experience w/ the Ambrosia above is a naive statement. 

The power amps in the 912 can not be isolated or heard w/o the internal preamp/volume control.  Hence, placing a second redundant preamp in front of it could hardly be expected to improve performance.

The comparison is only what it is.  The 912 pre outs are SE only while the Ambrosia is fully balanced.  The more difficult the load the more likely the Ambrosia would exceed the 912 performance as a preamp.  Bongo states the Ambrosia will drive 20 of his power amps w/o sweating & he's probably not exagerating (much). 

For a difficult load, I would recommend employing the 912 speaker outputs as a pre-out: at the load input the speaker output would be padded as follows to convert it to a line level: a 9k series resistor followed by 1k parallel resistor (1/8W OK).  The only potential downside is noise amplified, but it seems dead quiet so probably of little concern.

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #7 on: 16 Jun 2009, 06:00 pm »
where did you read all the stuff on Gedes, I am looking for some more stuff he has done.  Very interesting though.

Thanks
Jared

Search www.DIYAudio.com; also search Duke LeJeune, AudioKinesis here.  Duke's estimated $2500 SWARM 2.0 is the best sub system extant & I've heard just about any/all technology & products worth hearing.  The reeeeeeaaaaaal beauty of this sub technology is that it matches perfectly w/ small monitor speakers, which have a myriad of advantages over full range speakers.  Since adopting this technology it is my personal solid belief that there is really no such thing as a high-end full range speaker.  The only exception might be something w/ stereo sub towers filled w/ multiple bass drivers stretching from the floor to ceiling or thereabouts. 


bunnyma357

Re: $200 rcvr beats $11k separates
« Reply #8 on: 16 Jun 2009, 06:08 pm »
Is there something special about the 912, or is there a similar architecture/performance with newer Pioneer models?


Jim C

Tyson

Re: $200 rcvr beats $11k separates
« Reply #9 on: 16 Jun 2009, 06:09 pm »
I've been down this road myself, and my only advice is for people to live with both systems for a while before selling off the more expensive equipment.  For myself, I found that there were flaws with the "world beater" equipment that did not show up in an immediate A-B comparison, but rather revealed themselves over time.  Obviously all equipment has flaws, it's the nature of our hobby, I only caution people to listen over the long term and verify that you can actually live with it over time.  In my case, I could not, and sold off the "world beater" equipment and went back to separates. 

Having said all of that, I've not heard the gear mentioned here, so I can't comment directly on it's performances. 

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #10 on: 16 Jun 2009, 06:15 pm »
Is there something special about the 912, or is there a similar architecture/performance with newer Pioneer models?


Jim C

Unknown & apparently unknowable. 

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #11 on: 16 Jun 2009, 06:18 pm »
I've been down this road myself, and my only advice is for people to live with both systems for a while before selling off the more expensive equipment.  For myself, I found that there were flaws with the "world beater" equipment that did not show up in an immediate A-B comparison, but rather revealed themselves over time.  Obviously all equipment has flaws, it's the nature of our hobby, I only caution people to listen over the long term and verify that you can actually live with it over time.  In my case, I could not, and sold off the "world beater" equipment and went back to separates. 

Having said all of that, I've not heard the gear mentioned here, so I can't comment directly on it's performances.

Good advice, which I followed & recommend.  I sold the preamp after a few weeks & the power amp later.  I repeated the test several times, expecting to change my mind.  I also realize that the musical merits reveal over time.  I've never regretted the change for a minute.  I'm especially more & more convinced of the advantage over the Plinius.     

hoxuanduc

Re: $200 rcvr beats $11k separates
« Reply #12 on: 16 Jun 2009, 06:44 pm »

I have read prior raves about "Gainclone" amps but do not know exactly what it is & certainly have no idea of any similarities between Gainclone & the 912.  If you are stating the 912 is a Gainclone, why?  Are you a tech?  Have you compared the schematics? 

Of course I'm not saying it's a Gainclone.  Gainclones refer specifically to those using the 1875, 3875, 3886, 4780 or similar chips.  All I'm saying is they employ chip amplifiers rather transistors for the gain stage to ensure better matching and thermal management.

BTW after I read for post I searched for the 912 on eBay to see how easy it was to get.  None showed up!

I have a 4-page document covering Stan's IC, speaker & AC line cords, plugs, jacks, etc, etc.  I can't just take items out to make it shorter because, well I just wouldn't know how to edit it down.  BTW, I worked long & hard to make sure the recipe is accurate; there are/were a lot of cobbed together wrong & incorrectly modified recipes. 

Four pages is too long to post here; probably best in the DIY forum as a sticky or?  PM me your email & I'll attach it to an email.  Please just give Stan the credit for the recipe & me credit for the archiving.

Will do, thanks.

Duc

Niteshade

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Re: $200 rcvr beats $11k separates
« Reply #13 on: 16 Jun 2009, 06:59 pm »
I see you're comparing the 912 as a whole to the separates you once had. That didn't slip past me. My thoughts were leaning more towards dissecting the 912. When something like this comes up, it's fun to figure out ways to find out why something works as it does.

I still believe it would be interesting to see how well Pioneer's hybrid modules would operate in a stand-alone power amp configuration.  That way it would be possible to discern the module's performance by themselves and their contribution to the unit as a whole. There is allot of stuff going on inside a receiver. Must be the combination is a winner!


HT cOz

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Re: $200 rcvr beats $11k separates
« Reply #14 on: 16 Jun 2009, 07:10 pm »
So where can I buy this reciever for $200?

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #15 on: 16 Jun 2009, 07:18 pm »
Blair
Your job, should you decide to accept it, is to get a schematic of the 912 then send me a schematic for a standalone custom single channel amp tweaked to the max.  I'll pay for your time within reason (check w/ me first) & build the amp myself.  It would be fun to compare performance vs. the 912.

HTcoz
My second 912 should arrive in a few days, about $230 delivered.  Hope this thread doesn't make them too rare.  Everyone else is on their own.  Seriously, if I had to I'd pay a lot more than $200.   

Tyson
Believe me, till I heard the 912 to say I viewed the giant slayer threads w/ scepticism is an understatement.  In fact I disbelieved them all.  Regular folks (not that anyone in particular reading this is a regular folk) saying they liked something is different from Dr. Earl Geddes saying something met his proprietary & apparently well above industry norms lab test criteria & also matched the audio performance of his high end separates.
       

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #16 on: 16 Jun 2009, 07:26 pm »
That's a real interesting discovery. I wonder how much of this has to do with speakers as opposed to electronics, but I'm not qualified enough to be certain. All I know is that my first amp was a Pioneer Elite 47TX, and then later I tried some ATI amps. Based on my experience with those I would not recommend home theater amps or receivers (in general) for serious listening, but that's just my opinion, and obviously there are exceptions I'm unaware of.

These days I own a Plinius SA100MkIII, and it is clearly a major step up from where I started, at least to my ears. Perhaps if I had different speakers I would have a different reaction, but I won't know until I try that.

Great advice.  As posted my pure analog Trinaural main/center speaker is 8 Ohms nominal, its lowest impedance is 5.3 Ohms in a moderately narrow band; L/R Spica TC-60 are likely a moderate load. 

The further the load falls below 8 Ohms the less well matched is the 912, which is rated ONLY at 8 Ohms (no 4 Ohm rating & apparently not recommended).  I'll quote the manual upon request on the issue of load impedance.

It's very important to note that all A-B auditioning was done in purely stereo w/o subs, monitors only.     

zybar

Re: $200 rcvr beats $11k separates
« Reply #17 on: 17 Jun 2009, 12:15 pm »
I had a $7500 James Bongiorno-designed Spread Spectrum Technologies (SST) Ambrosia preamp w/ phono.  For reference, more widely distributed preamps in a similar performance category to the Ambrosia are the 1st-edition $17k VTL 7.5 & Krell Evo (estimate $15k).  Bongiorno invented the dual-differential full-complementary circuit in most high-end pre & power amps. 

The Plinius SA-50 Mk 3 power amp from New Zealand is often considered to be their best (50W pure class A, circa 2001, $3500 MSRP).  The $19k darTZeel (also from NZ) is an ultra-refined version of this Plinius circuit.  Plinius abandoned their lower-power pure class A designs when the 50 was discontinued in favor of higher powered & higher cost amps.  I am familiar w/ their popular SA250 Mk 4 & prefer the 50.  The 50 was probably the best ss I ever owned (till this).
     

Couple quick points...

darTZeel's amp is not based on any of the Plinius amps.

darTZeel is not from New Zealand, they are a Swiss company.

If you would like to read more about this amp, here is a good place to start:

http://www.dartzeel.com/index.php?option=com_content&task=view&id=47&Itemid=69

George

mgalusha

Re: $200 rcvr beats $11k separates
« Reply #18 on: 17 Jun 2009, 04:03 pm »
A few thoughts.

I am a firm believer that Dr. Geddes knows what he is talking about as I built a pair of the Abbeys and like them very much. I am also firmly convinced of his multiple sub approach and am using 3 of GR Research/Rythmik Direct Servo subs in 1.5cf sealed enclosures and have what I believe to be superb bass, certainly the best I've ever had in my home.

One of his points about the Pioneer is that is has very low crossover distortion, which is very important when using high sensitivity speakers, as much of the time the power level is low enough to make this important.

eServiceInfo has the service manual available for the Pioneer available for free download however it's a multipart RAR file and they have a download limit. For anyone who would like a copy of the PDF I've posted it here

The amplifier modules are listed as PAC011A IC and can be purchased here: http://www.pronto.com/product/pioneer-pac011a-ic-hybrid-p_1105181166

I didn't see a data sheet during my search. I suspect it's a pioneer proprietary piece and they have no real need to publish one.

I have not heard one of these but I have played with other chip amps and they can sound very good indeed, as long as they are not pushed to the limit. The National LM3886 for example is rated at 38W into 8R and 68W into 4R and is fully discrete in the chip and uses current sources to bias the transistors, a very good thing. But if pushed too hard the protection circuitry will step in and throttle down the output. From what I understand this can have audible consequences. No idea what type of protection the Pioneer uses but I imagine they do have something in there for protection.

As mentioned, Pioneer only rates it into a 8 ohm load, which of course almost no speaker is. The Abbey for instance would be considered an 8R load but it runs anywhere from 5.5 ohms at 150Hz to a bit over 25 ohms at the crossover frequency. It stays above 10 ohms from 300Hz to almost 20K, so a very friendly load for something like the Pioneer and I'm sure that is partly why it works so well for Earl. It sounds like your speakers are also fairly benign. Sadly many speakers are not so friendly and I doubt the Pioneer would perform nearly as well, which is too bad as lots of folks would undoubtedly like to put some $$ back in their pockets.

All that said, I've tried a half dozen amps with the Abbeys and have no trouble hearing a difference and all have strengths and weaknesses. I saw something by an amp designer somewhere, who I cannot remember, saying something to the effect that most of the differences people hear in amplifiers is related to how badly the amp misbehaves from interaction with the load. I'm sure this doesn't cover everything but it does cover a lot. Even speakers that don't drop real low in impedance usually present all kinds of phase angles which can play hell with the feedback circuits and this of course affects the linearity of the amplifier. IMO this is a big part of why proper speaker/amp/cable matching can be difficult and what keeps audiophiles trying for the combination that makes them happy.

Just my nickels worth. :)

mike

James Romeyn

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Re: $200 rcvr beats $11k separates
« Reply #19 on: 17 Jun 2009, 05:20 pm »
I had a $7500 James Bongiorno-designed Spread Spectrum Technologies (SST) Ambrosia preamp w/ phono.  For reference, more widely distributed preamps in a similar performance category to the Ambrosia are the 1st-edition $17k VTL 7.5 & Krell Evo (estimate $15k).  Bongiorno invented the dual-differential full-complementary circuit in most high-end pre & power amps. 

The Plinius SA-50 Mk 3 power amp from New Zealand is often considered to be their best (50W pure class A, circa 2001, $3500 MSRP).  The $19k darTZeel (also from NZ) is an ultra-refined version of this Plinius circuit.  Plinius abandoned their lower-power pure class A designs when the 50 was discontinued in favor of higher powered & higher cost amps.  I am familiar w/ their popular SA250 Mk 4 & prefer the 50.  The 50 was probably the best ss I ever owned (till this).
     

Couple quick points...

darTZeel's amp is not based on any of the Plinius amps.

darTZeel is not from New Zealand, they are a Swiss company.

If you would like to read more about this amp, here is a good place to start:

http://www.dartzeel.com/index.php?option=com_content&task=view&id=47&Itemid=69

George

Thanks for correcting the location of darTZeel.  I apparently came to this conclusion wrongly after hearing about the shared Plinius circuit.   

Till the schematics of both the Plinius SA-50 & the darTZeel are published & viewed side by side, readers are encouraged to make their own conclusions about similarity &/or disimilarity between them (someone denying similarity has no more or less evidence than someone who claims there is a similarity).  I'm thinking darTZeel has more to gain by denying any similarity (marketing reasons), while the source who mentioned the similarity has nothing to gain by making a false claim plus he's in a position to know.     

The person who mentioned that the darTZeel was a highly, highly refined version of the SA-50 circuit has been an industry professional for many decades including current position as a reviewer, professional singer of classical French music, an attorney, a record producer & recording engineer.  This person had no known reason to make up a similarity where none exists; also he would not likely make the statement w/o good evidence.  He's owned the SA50 & reviewed the darTZeel.  A close associate of his (I've talked several times to the same person) is tech who now works at one of the most respected digital audio companies (pro & consumer gear) & that same tech was associated w/ the Plinius importer at one time.  So.....I'm betting on the similarity in circuitry.  It may be noteworthy that, per darTZeel, the first NHB-108 arrived '99 (IIRC); the first SA-50 arrived a few years prior.  Again, readers can decide for themself based on these notes.  I haven't searched for an SA50 schematic but noticed dz has published some schematics.   

No one ever said dz copied anyone or anything BTW.  Maybe both companies arrived at the same circuit purely independently.  Maybe Plinius got their earlier while dz refined it & refined it to its current state of being apparently one of the best amps, period (something I would never imply about the SA50).           

But please be clear, I can't remember the exact words concerning the differences, but it was something like "very highly ultra refined" or even more emphatic that there were many areas cleaned up to provide the best SS performance & maybe the best amplifier source period (the darTZeel that is).   

Also, my own understanding is there are indeed obvious architecture similarities, such as a sum total two active devices per gain stage.  I'm thinking the SA50 has the same number of total active devices, being 6 per ch.  The following I'm less sure of but I believe both use dual NPN devices per gain stage vs. industry norm of one NPN paired w/ PNP.  IIRC Plinius was the first to claim the benefits of one pair active devices; several such as Gamut & another German company have copied this philosophy.
 
« Last Edit: 17 Jun 2009, 08:47 pm by ro7939 »