Classé Sigma Series

[BWLover]

Has anyone heard anything from this new series? Just wondering how it stacks up with it being class D amplifiers and all...


Bowers & Wilkins 683S1 Speakers
Rotel RB-1090 2 Channel Amp
Rotel RC-1082 Stereo Pre Amp
Rotel RCD-1072 CD Player
Pro-Ject Debut Carbon w/ Ortofon 2M Red (sitting on a piece of slate supported by 3 "solid tech feet of silence" isolation feet)
Rotel RLC-1040 Power Conditioner
Shynyata Research SR-Z1 Power Outlet & Venom 3 Power Cords x 4
Tara Labs RSC Vector 1 Speaker Cables & Interconnects
Primacoustic Room Treatments

[Patrick Butler]

Hi BW Lover,

I've heard my fair share of Class D based amplifiers. Some are horrible (my car stereo comes to mind) and some just sound like really good amplifiers that happen to be small, efficient and Class D (Classé Sigma and Devialet spring to mind.) The only issues around Class D and sound quality are the ones that many companies don't bother to address. This is understandable. Unlike most amplifier designs, you can't build a Class D amp on a kitchen table. They are inherently complicated and a solid background in DSP engineering is a requirement.

Sigma doesn't really sound like anything. I understand that this might seem strange to say, especially considering my affiliation with Classé. That said, electronics that don't have an identifiable "sound" is the goal of engineering high performance audio. Unless you have a specific sound in mind that you are chosen after, I think you'd like listening to this series.

Best Regards,

Patrick Butler
B&W Group North America

[bauhaus]

Patrick, I'm currently using the Classé SSP 800 with the Rotel RMB-1585 power amp. Do you think I will get overall significant improvement sonically if upgrading to either the Classé Sigma Amp5 or the Classé CA-5300 amp with the SSP 800? My speakers are : B&W CM10 (front), B&W CMC2 S2 center channel, B&W CM6 (surrounds).

[Kal Rubinson]

The only issues around Class D and sound quality are the ones that many companies don't bother to address. This is understandable.

Can you elaborate on what those issues are?

[bauhaus]

I have heard the Sigma series combo and they sounded phenomenal for stereo music. QUOTE=BWLover;611117]Has anyone heard anything from this new series? Just wondering how it stacks up with it being class D amplifiers and all...


Bowers & Wilkins 683S1 Speakers
Rotel RB-1090 2 Channel Amp
Rotel RC-1082 Stereo Pre Amp
Rotel RCD-1072 CD Player
Pro-Ject Debut Carbon w/ Ortofon 2M Red (sitting on a piece of slate supported by 3 "solid tech feet of silence" isolation feet)
Rotel RLC-1040 Power Conditioner
Shynyata Research SR-Z1 Power Outlet & Venom 3 Power Cords x 4
Tara Labs RSC Vector 1 Speaker Cables & Interconnects
Primacoustic Room Treatments[/QUOTE]

[Kal Rubinson]

I have 3 of the Sigma Monos now, so I was hoping to get more insight into why they sound as they do.

[bauhaus]

Hi Kal,
I remembered reading your review on the Classe Sigma SSP last year and I thought that you amplified the Sigma SSP with the Sigma Amp5.
By the way, what preamp or av preamp processor did you use when reviewing the Rotel RMB-1585 amp? What would you say performance wise of the Rotel RMB-1585 amp against the Classe Sigma Amp5 and other multi-channel amps from McIntosh and your beloved older Bryston amp? Would you say that the Classe Sigma Amp5 or other multi-channel amps from McIntosh & Bryston would be a significant step up sonically from the Rotel RMB-1585 amp?
I currently own the Classe SSP 800 with the Rotel RMB-1585 amp. Source component includes the Oppo bdp-105.
My front speakers : B&W CM10 floorstanders. Center channel : B&W CMC2 S2. Surrounds : B&W CM6 bookshelf speakers.
Much appreciated and thank you.

[Kal Rubinson]

Off the top of my head, I cannot answer you but the identity of the processor in use is, I am certain, in the review. I cannot say more about the RMB-1585 since I have not heard it since the review. I think the Amps5 was a step up from the Bryston at the time. All this was in CT.

As for the Mac, it lives in NYC and has not been compared with the others mentioned (because I cannot move it).

[Patrick Butler]

Hi Kal,

Three particular issues:

1. Dead-band time. The output devices in Class D designs need to be turned completely off as the amp transitions from + to -. If they are not completely off, the resultant dead short leads to catastrophic failure of the amplifier. Dead-band time leads to high amounts of THD, which requires lots of global negative feedback, which results in greater Transient Intermodulation Distortion. Not pleasant to listen to. The more dead-band time you add, the more reliable your design will be over time, but the worse it will sound.

2. Many Class D designs switch at relatively low frequencies, and the output filter then needs to operate near the audio band which results in high frequencies being rolled off, which results in a lack of air and a sense of space in recordings.

3. The switch mode power supplies used in many Class D amplifier designs inject large amounts of noise into the amplifier and the AC supply, negatively impacting both. This is part of the reason why there is a community of people building linear power supply upgrades for products that come with wall warts (which are usually switch mode power supplies.) However, those linear supplies aren't without their downsides. As always, there are no free lunches.

If anyone is interested, I might be able to involve Dave Nauber from Classé in a deeper discussion of Class D (he's the engineer- I'm not.)

Regards,

Patrick
B&W Group North America

Can you elaborate on what those issues are?

[Patrick Butler]

Hi bauhaus,

Nice setup!

The Sigma AMP 5 and the CA-5300 are noticeably clearer sounding designs. Clarity brings greater resolution, and dynamic range. I've compared the stereo versions of the RMB-1585 and the AMP5 with CM10, and it took no effort to discern the differences. If you have the budget and the space- CA-5300. For roughly half the price and a much smaller commitment in physical real estate, the AMP5 is pretty awesome.

Regards,

Patrick
B&W Group North America

Patrick, I'm currently using the Classé SSP 800 with the Rotel RMB-1585 power amp. Do you think I will get overall significant improvement sonically if upgrading to either the Classé Sigma Amp5 or the Classé CA-5300 amp with the SSP 800? My speakers are : B&W CM10 (front), B&W CMC2 S2 center channel, B&W CM6 (surrounds).

[bauhaus]

Thanks Patrick. Did you mean the Rotel RB-1582 Mkll when you said the stereo version of the Rotel RMB-1585?
So, the Classe Sigma Amp5 is a step up sonically over the Rotel RMB-1585? Ok. I will probably upgrade to the Classe Sigma Amp5 then.
Is the Classe CA-5300 a step up sonically over the Sigma Amp5? If it is, I might go for the CA-5300 then. Aesthetically it will match my SSP 800 too. The CA-5300 puts out 300 wpc @ 8 ohms whereas the Sigma Amp5 & the Rotel RMB-1585 both put out 200 wpc @ 8 ohms.
Do you think that the CA-5300 amp will be overkill for my CM10?
Thanks.

[Alaric]

If anyone is interested, I might be able to involve Dave Nauber from Classé in a deeper discussion of Class D (he's the engineer- I'm not.)

Speaking for myself (and likely a few others) knowledge is always welcome. I know I've had multiple debates in other places regarding Class D. Some love anything Class D because "Digital is better/newer/trendier, etc.." Some hate it because it's "Digital and music is analog!". Both extremes seem to lack a solid foundation of the basics of what it takes to produce a good Class D amp or how good they can really be when done right. If you can corral an eng-i-neer who can get some of us (ok, me) up to speed on the fundamentals that would be great. I'd love to have more ammo than "Because Patrick and Kal said so!". Although both are valid proofs in my book. I don't expect an online ee degree, but I'm fair certain my head will hold a few more facts before it fills up.

[Patrick Butler]

Hi bauhaus,

Yes, I was referring to the RB-1582MkII.

In order of preference:

1. CA-5300- not overkill.
2. AMP5
3. RMB-1585

Regards,

Patrick
B&W Group North America

Thanks Patrick. Did you mean the Rotel RB-1582 Mkll when you said the stereo version of the Rotel RMB-1585?
So, the Classe Sigma Amp5 is a step up sonically over the Rotel RMB-1585? Ok. I will probably upgrade to the Classe Sigma Amp5 then.
Is the Classe CA-5300 a step up sonically over the Sigma Amp5? If it is, I might go for the CA-5300 then. Aesthetically it will match my SSP 800 too. The CA-5300 puts out 300 wpc @ 8 ohms whereas the Sigma Amp5 & the Rotel RMB-1585 both put out 200 wpc @ 8 ohms.
Do you think that the CA-5300 amp will be overkill for my CM10?
Thanks.

[Patrick Butler]

Hi Alaric,

I'm happy to each out to Dave Nauber, but the forum members and whomever is the moderator should give the ok ahead of time.

Yes, there is a general lack of clarity around amplification technologies. Class D has been rightly bashed for being sub-optimal when it comes to high-fidelity applications. As one of my colleagues pointed out recently, transistors in general were once viewed as solid step backwards when they were new on the scene. That is no longer the case, as the technology improved and the fidelity along with it. The same is equally true for Class D, but the technology is decidedly more complicated and difficult to implement.

Regards,

Patrick
B&W Group North America

Speaking for myself (and likely a few others) knowledge is always welcome. I know I've had multiple debates in other places regarding Class D. Some love anything Class D because "Digital is better/newer/trendier, etc.." Some hate it because it's "Digital and music is analog!". Both extremes seem to lack a solid foundation of the basics of what it takes to produce a good Class D amp or how good they can really be when done right. If you can corral an eng-i-neer who can get some of us (ok, me) up to speed on the fundamentals that would be great. I'd love to have more ammo than "Because Patrick and Kal said so!". Although both are valid proofs in my book. I don't expect an online ee degree, but I'm fair certain my head will hold a few more facts before it fills up.

[Alaric]

It's my understanding that the only digital in Class D is the switching, and that the op amps are right where they've always been, and it's the filtering (as you said) of the switch noise that makes or breaks the sound quality along with the quality of the op amps. I'll check with some higher ups here and see if we can't generate an invite.

edit: I made inquiries last night regarding the opportunity to have a real, live Classe engineer stop by. That would be a great opportunity for us. :T

[Audio_ElF]

It's my understanding that the only digital in Class D is the switching,

As I recall switching amplifiers are only called "Class D" as it was the next convinience class name after Class A, Class B and Class C. Because of the switching nature people assumed D was for Digital.

[wkhanna]

I'm happy to reach out to Dave Nauber, but the forum members and whomever is the moderator should give the ok ahead of time.


Regards,

Patrick
B&W Group North America

i see no reason that Mr. Dave Nauber should not be allowed to participate in any discussions.
we are all here to learn.

[Patrick Butler]

I'll reach out to Dave and see when he might have time to participate.

Best Regards,

Patrick
B&W Group North America

i see no reason that Mr. Dave Nauber should not be allowed to participate in any discussions.
we are all here to learn.