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post #7261 of 7282 Old Yesterday, 06:03 AM
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Originally Posted by stevekale View Post
Let me guess, you are still stuck on Class A as well?
More like AB, but sure, and so do 90% of exhibitors at the last Los Angeles high end audio show.

But I will be the last person to tell anyone my way is the right way. If someone is happy with class D I have no criticism whatsoever.

Regards, Can
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post #7262 of 7282 Old Yesterday, 07:19 AM
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As in Class AB is preferred to Class A or Class B or as in anything from Class A to B and between?

PS: you would enjoy the opening chapter of Douglas Self's "Audio Power Amplifier Design Handbook" 6th ed. Worth the cover price for that chapter alone.

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post #7263 of 7282 Old Yesterday, 07:49 AM
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Quote:
Originally Posted by stevekale View Post
1. As in Class AB is preferred to Class A or Class B or as in anything from Class A to B and between?

2. PS: you would enjoy the opening chapter of Douglas Self's "Audio Power Amplifier Design Handbook" 6th ed. Worth the cover price for that chapter alone.
1. Nothing complicated Steve, simply that the first few watts are class A, then amp switches to class AB. My Krell more than my Classe, because it is always steaming hot.

2. Quoting book and suggest reading? Are you kidding? No I wouldn't! One, my life is not that boring!!! Two, Holy Macaroni if you are implying (pardon me if you are not) reading book make you or me some expert at amp design or help to choose which amp, I am afraid not, at least not for me. I would just let the listening test be the arbitrator, but of course you already know this.

Are you switching to a class D amp? If so which one?

Regards, Can
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post #7264 of 7282 Old Yesterday, 08:50 AM
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Switching to class D - nope; not yet anyway. But I am learning a lot about amp design and I have been following a design/build that I'm tempted to build myself as it's specs are frankly awesome (and schematics etc freely available for non-commercial purposes). Might be a fun project for the winter months.

BTW I just read this passage in the book I referenced above:

Quote:
Misinformation also arises in the purely technical domain, I have also found some of the most enduring and widely held technical beliefs to be unfounded. For example, if you take a Class-B amplifier and increase its quiescent current so that it runs in Class-A at low levels, i.e. in Class-AB, most people will tell you that the distortion will be reduced as you have moved nearer to Class-A condition. This is untrue. A correctly configured amplifier gives more distortion in Class-AB, not less, because of the abrupt gain changes inherent in switching from A to B every cycle.

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Just comment about class D since this this is a Theta thread. I have been allergic to class d... With Hypex and the Prometheus it is completely different. They are much better than e.g. Jeff Rowland 301 class d monos. In direct comparison with Electrocompaniet Nemo class A the Prometheus are also noticeably better, not only more resolution and tighter bass as you could expect from this technology, but actually also more musical in the midrange where Nemos are quite good. The Prometheus are dead quiet and create a tremendous and precise room, like the real event. Better also than what I have heard from Burmester (911) and Accuphase (A65).
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post #7266 of 7282 Old Yesterday, 10:40 AM
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Originally Posted by Armand07 View Post
also more musical in the midrange
what on earth is meant by this?

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post #7267 of 7282 Old Yesterday, 11:16 AM
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Not harsh or cold, but liquid and delicate

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post #7268 of 7282 Old Yesterday, 11:20 AM
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Quote:
Originally Posted by stevekale View Post
Switching to class D - nope; not yet anyway. But I am learning a lot about amp design and I have been following a design/build that I'm tempted to build myself as it's specs are frankly awesome (and schematics etc freely available for non-commercial purposes). Might be a fun project for the winter months.

BTW I just read this passage in the book I referenced above:
Steve you are in another league compared to me then. The only thing I have soldered are interconnects and speaker drivers, and they are the nastiest solder joints I've ever seen.

What are the specs of the amp your are building? Power per channel, doubling of power with halving of resistance? Class?

The quote you gave: is author advocating class B? Doesn't that have crossover distortion? Nearly all amps that I've owned, or have read about, are A then A/B, not B; I've always thought that industry's accepted standard?

Regards, Can
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post #7269 of 7282 Old Yesterday, 11:24 AM
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Quote:
Originally Posted by Armand07 View Post
Just comment about class D since this this is a Theta thread. I have been allergic to class d... With Hypex and the Prometheus it is completely different. They are much better than e.g. Jeff Rowland 301 class d monos. In direct comparison with Electrocompaniet Nemo class A the Prometheus are also noticeably better, not only more resolution and tighter bass as you could expect from this technology, but actually also more musical in the midrange where Nemos are quite good. The Prometheus are dead quiet and create a tremendous and precise room, like the real event. Better also than what I have heard from Burmester (911) and Accuphase (A65).
Good review; you've certainly done your "homework" with the comparisons.

The Jeff Rowland class D does NOT use Hypex module?

Regards, Can
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post #7270 of 7282 Old Yesterday, 12:20 PM
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Question Cabling the Casablanca IV

While I like most everything about the CBIV, as a long-time audiophile one aspect of this new version of the Casablanca that does not delight me is its offering of non-HDMI inputs. To be specific, there aren't any AES/EBU audio inputs, nor are there any BNC digital ones.


I have, consequently, some "obsolete" very expensive interconnects, which leads to my question of retermination. Both of my CD transports have BNC outputs. Should I reterminate both ends of my currently useless digital cables to RCA, or should I keep the BNC connector on the end which connects to the transport and just "downgrade" the other end?


Obviously, my aim is to optimize the performance of those cables, and I appreciate feedback both scientifically- and aurally-based.


Thanks!

Jonathan
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post #7271 of 7282 Old Yesterday, 12:57 PM
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Quote:
Originally Posted by cannga View Post
Good review; you've certainly done your "homework" with the comparisons.

The Jeff Rowland class D does NOT use Hypex module?
No, they were the original, classic class D design, but among the best of these. Jeff Rowland has gone back to class a/b since then.
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post #7272 of 7282 Old Yesterday, 01:14 PM
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Originally Posted by jmeyers View Post
While I like most everything about the CBIV, as a long-time audiophile one aspect of this new version of the Casablanca that does not delight me is its offering of non-HDMI inputs. To be specific, there aren't any AES/EBU audio inputs, nor are there any BNC digital ones.


I have, consequently, some "obsolete" very expensive interconnects, which leads to my question of retermination. Both of my CD transports have BNC outputs. Should I reterminate both ends of my currently useless digital cables to RCA, or should I keep the BNC connector on the end which connects to the transport and just "downgrade" the other end?


Obviously, my aim is to optimize the performance of those cables, and I appreciate feedback both scientifically- and aurally-based.


Thanks!
Don't sweat it. Get a bunch of BNC to RCA adaptors for $1 a piece and be done. I know these sort of compromises cause the by nature anally retentive audiophiles (which include me) immense anxiety about performance degradation, but trust me, you wont hear it.
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post #7273 of 7282 Old Yesterday, 03:23 PM
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Originally Posted by cannga View Post
What are the specs of the amp your are building? Power per channel, doubling of power with halving of resistance? Class?
Thinking of building... I've a lot more to learn first (I'd like to understand things better rather than blindly assemble) and another project to finish. To be absolutely clear, I could not in any way design this amp but I do think I could build it.

"200W 8R / 400 4R Class AB

Real life THD+N performance is about 0.0015% at 20kHz@200W@8R (80kHz bandwidth).

SNR in reference to 1kHz@200W@8R output level:
>125 db - A-weighted
>121 db - BW 20kHz
>117 db - BW 80kHz
>111 db - Full bandwidth (~ 500kHz limit of VP-7723)"

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Originally Posted by cannga View Post
The quote you gave: is author advocating class B? Doesn't that have crossover distortion? Nearly all amps that I've owned, or have read about, are A then A/B, not B; I've always thought that industry's accepted standard?
From the same author (who is a giant in this field):

Quote:
It has proved possible to take the standard Class-B power amplifier configuration, and by minor modifications, reduce the distortion to below the noise floor at low frequencies. This represents approximately 0.0005 to 0.0008% THD, depending on the exact design of the circuitry, and the actual distortion can be shown to be substantially below this if spectrum analysis techniques are used to separate the harmonics from the noise.
Quote:
...Class-A amplifiers are not just inefficient; with musical signals they are hopelessly inefficient - somewhere around 1%. There is now really no need to resort to Class-A just to get low distortion, so their attraction is as much philosophical as anything else. I believe you should think hard before planning to build one with more output than about 20W / 8R.
But customers may expect something different....

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post #7274 of 7282 Old Yesterday, 03:27 PM
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Originally Posted by jmeyers View Post
To be specific, there aren't any AES/EBU audio inputs
Well there is one, not that it is any better than coaxial cable over short distances. BNC-phono converter will be fine for your BNC terminated cables. Don't let past gullibility worry you further.

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Originally Posted by Armand07 View Post
Not harsh or cold, but liquid and delicate
Ah, completely clear now

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Quote:
Originally Posted by Armand07 View Post
Just comment about class D since this this is a Theta thread. I have been allergic to class d... With Hypex and the Prometheus it is completely different. They are much better than e.g. Jeff Rowland 301 class d monos. In direct comparison with Electrocompaniet Nemo class A the Prometheus are also noticeably better, not only more resolution and tighter bass as you could expect from this technology, but actually also more musical in the midrange where Nemos are quite good. The Prometheus are dead quiet and create a tremendous and precise room, like the real event. Better also than what I have heard from Burmester (911) and Accuphase (A65).
I was the first person in the whole world to have the Prometheus outside of Theta Digital - got 5 of them. HA! Next you. Then a few others. Better than my prior Theta Citadel 1.5s. I luv 'em!

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post #7277 of 7282 Old Yesterday, 11:32 PM
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Originally Posted by jmeyers View Post
While I like most everything about the CBIV, as a long-time audiophile one aspect of this new version of the Casablanca that does not delight me is its offering of non-HDMI inputs. To be specific, there aren't any AES/EBU audio inputs, nor are there any BNC digital ones.

Thanks!
The CBIV has an AES/EBU input. I am using it...
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post #7278 of 7282 Old Today, 05:29 AM
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Originally Posted by jmeyers View Post
Should I reterminate both ends of my currently useless digital cables to RCA, or should I keep the BNC connector on the end which connects to the transport and just "downgrade" the other end?

Hi Jonathan, you are asking about BNC input, not XLR right? Theta IV does have one XLR dig input if I am not mistaken.

Regarding your BNC/BNC cable, IMHO, most definitely re-terminate one end only! My Illuminati digital cable actually was custom built this way: BNC at one end connected to my transport, RCA at the other end connected to my DA converter.

Alternatively, you could buy new cable that is built like mine; one place I could recommend is http://www.bluejeanscable.com/store/...udio/index.htm . They have both BNC-RCA digital cables and BNC-RCA adapters.

Regards, Can
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post #7279 of 7282 Old Today, 07:05 AM
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Quote:
Originally Posted by Armand07 View Post
The CBIV has an AES/EBU input. I am using it...
Armando,

I should have stated "no AES/EBU analog inputs." Like you, I am already using the digital one.

Jonathan
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Originally Posted by jmeyers View Post
Armando,

I should have stated "no AES/EBU analog inputs." Like you, I am already using the digital one.
AES/EBU is a digital protocol. I guess you mean XLR / Balanced.
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Quote:
Originally Posted by cannga View Post
More like AB, but sure, and so do 90% of exhibitors at the last Los Angeles high end audio show.

But I will be the last person to tell anyone my way is the right way. If someone is happy with class D I have no criticism whatsoever.
Most solid state power amps these days from the $399 Denon receiver to many high end brands are class B. Tube push pull amps are most always class AB. But a solid state class AB amp can be built, as some are.

Class A single ended? IMO, that's a cult following dead 1920s technology. Again JMO. I guess with horns it can work.

Douglass Self believes a well designed class B amp is superior to a class AB amp. He also thinks crossover distortion is not a significant issue anymore with modern matched transistors. There are other equally accomplished designers that disagree.

I run pure class A solid state amps on my LCR tweeters. 20 watts RMS per driver. In theory it's cleaner for tweeter duty. In practice I really can't hear much if any difference to class B.

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post #7282 of 7282 Old Today, 09:16 AM
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Quote:
Originally Posted by jmeyers View Post
While I like most everything about the CBIV, as a long-time audiophile one aspect of this new version of the Casablanca that does not delight me is its offering of non-HDMI inputs. To be specific, there aren't any AES/EBU audio inputs, nor are there any BNC digital ones.


I have, consequently, some "obsolete" very expensive interconnects, which leads to my question of retermination. Both of my CD transports have BNC outputs. Should I reterminate both ends of my currently useless digital cables to RCA, or should I keep the BNC connector on the end which connects to the transport and just "downgrade" the other end?


Obviously, my aim is to optimize the performance of those cables, and I appreciate feedback both scientifically- and aurally-based.


Thanks!
An BNC to RCA adaptor is not an issue at all for digital audio. I do agree an RCA to BNC cable is more elegant but one need not spend a lot here either. The BlueJeans cables mentioned above are indeed an excellent value and use raw cable stock from recognized professional wire manufactures. Most audiophile cables have no traceable origions of their raw materials. I would stay away from the Belden 1694 type cable for digital audio. It's just gross overkill, heavy, and thick. Belden 1505 is more than sufficient for home digital audio needs. In fact it's used for runs of hundreds of feet in broadcast and mastering facilities. 1694A is more suited to SDI video at 1.5 and 3gbs, quite a difference from the 3mbs rate of 48K AES/SPDIF.

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