Home |
Search |
Today's Posts |
#1
|
|||
|
|||
Recommendations for 5 channel power amp
Hi Guys,
Looks like it's time for a new amp for the soundroom. I'll probably need to go 5 channels and will have to be under 3000 euro's. I'm on the east side of the pond nowadays. Any recommendations? Possibilities: NAD Silverline S250 Rotel RMB-1095 Thanks, Wessel |
#2
|
|||
|
|||
|
#3
|
|||
|
|||
Check out this Primare
http://www.primare.net/swwwing/app/c...81&PARENT=1055 "Wessel Dirksen" wrote in message ... Hi Guys, Looks like it's time for a new amp for the soundroom. I'll probably need to go 5 channels and will have to be under 3000 euro's. I'm on the east side of the pond nowadays. Any recommendations? Possibilities: NAD Silverline S250 Rotel RMB-1095 Thanks, Wessel |
#4
|
|||
|
|||
Outlaw Audio has a 100W and 200W 5 channel (& 7 channel) amps that are
highly regarded - and not super expensive. Plinius, and Cary make 5 channel amps for ~$4k, too. On 8/24/04 7:26 PM, in article , "Philip Meech" wrote: I would look at Aragon and Adcom (especially the preamp). Wessel Dirksen wrote: Hi Guys, Looks like it's time for a new amp for the soundroom. I'll probably need to go 5 channels and will have to be under 3000 euro's. I'm on the east side of the pond nowadays. Any recommendations? Possibilities: NAD Silverline S250 Rotel RMB-1095 Thanks, Wessel |
#5
|
|||
|
|||
The whole NAD silverline is zero negative feedback.
I doubt that... at least, not as it's written there. They may very well have no _global_ negative feedback. They almost certainly have _local_ negative feedback, in each individual stage. You need at least some local feedback in order to make each stage (e.g. input, driver, output) linear enough to deliver acceptable performance. Local feedback may be something as simple as an emitter or source resistor. Yup... I just checked their brochure, and they state that (e.g.) "[T]he S300's amplifier circuits avoid overall ('global') negative feedback altogether." Question: Is negative feedback a big deal or not? Depends on what kind, how you use it, and other details of the circuit. In general, in order to get either a tube or transistor (bipolar or MOSFET) to amplify without distortion, you need at least _some_ feedback in order to linearize the device's behavior. The feedback may be local (e.g. the output of the device is somehow fed back to the device's input, with appropriate phase inversion), or it may "reach back" to the beginning of an earlier stage in the amplifier (this is often referred to as "global" negative feedback). If you have no negative feedback at all, you're going to be very limited in both the distortion level you can achieve, and the amount of power you can deliver. Some designers prefer to use only local (single-stage) feedback - in effect, making each stage of the amplifier acceptably linear (low-enough distortion), and accepting that the remaining distortions are going to add up. This appears to be what NAD has done in the Silver series. Some designers prefer to use both local feedback, and some amount of global feedback. Done well, this can lower the total distortion level. Done badly, it can cause problems... in particular, "ringing" or other forms of instability. [The cause of these stability problems has been known for decades, and designers really shouldn't be making this sort of mistake today, but it's always possible...] Some designers prefer to use only local feedback to reduce distortion in the audio spectrum, but to include a low-speed global feedback loop to "null out" any DC offset created by any of the stages in the amp. I believe it's possible to produce excellent, audibly-transparent amplifiers with any of these approaches. It's also possible to yngvi up a design which uses any of these, and generate various sorts of distortion (some of which may be euphonic, and some of which may sound downright nasty). I once had a chance to compare 2 similar tube amps built by a local tube tweek in Holland, One was with some kind of config with a bit of negative feedback, and the other with absolutely none. The result: I really felt the one with no negative feedback was more detailed. (I was blinded later when I really wanted to know) The amps were identical outside and in. I could discern the difference reliably not only because of the detail, but also the bass sounded tighter with the neg feedback. But the clarity was noticable. This might indicate more accuracy in the amp without global feedback, or it might indicate that the amp without global feedback was actually introducing a slight high-frequency boost for some reason. Impossible to tell from your description, I'm afraid. |
#6
|
|||
|
|||
Looks like it's time for a new amp for the soundroom. I'll probably need to
go 5 channels and will have to be under 3000 euro's. I'm on the east side of the pond nowadays. Any recommendations? BRBR 5 ch? What is your application? If its home theater, its 7 channel these days, even Dolby has adapted 7 channel with IIx. Regards, Jay Bala. |
#7
|
|||
|
|||
|
#8
|
|||
|
|||
B&D wrote:
On 8/24/04 11:13 PM, in article , "Dave Platt" wrote: The whole NAD silverline is zero negative feedback. I doubt that... at least, not as it's written there. They may very well have no _global_ negative feedback. They almost certainly have _local_ negative feedback, in each individual stage. You need at least some local feedback in order to make each stage (e.g. input, driver, output) linear enough to deliver acceptable performance. Not to mention to maintain stability into all kinds of loads!! Uhh, a circuit with no feedback will be stable. Feedback is not used to provide stability. Instability is the result of incorrectly applying feedback. Local feedback may be something as simple as an emitter or source resistor. Yes - but I think they were talking about loop feedback, not ballasting resistors. Uhh, using emitter resistor or source resistor *is* applying feedback. You should be able to clearly visualize the feedback loop. |
#9
|
|||
|
|||
"Jay1Bala" wrote in message
... Looks like it's time for a new amp for the soundroom. I'll probably need to go 5 channels and will have to be under 3000 euro's. I'm on the east side of the pond nowadays. Any recommendations? BRBR 5 ch? What is your application? If its home theater, its 7 channel these days, even Dolby has adapted 7 channel with IIx. Regards, Jay Bala. Sorry, only en extremis. Most home theatre is still 5.1. 7.1 "capability" is now featured, but usually only practiced in the most expensive systems. |
#11
|
|||
|
|||
B&D wrote:
On 8/26/04 7:17 PM, in article , "chung" wrote: B&D wrote: On 8/24/04 11:13 PM, in article , "Dave Platt" wrote: The whole NAD silverline is zero negative feedback. I doubt that... at least, not as it's written there. They may very well have no _global_ negative feedback. They almost certainly have _local_ negative feedback, in each individual stage. You need at least some local feedback in order to make each stage (e.g. input, driver, output) linear enough to deliver acceptable performance. Not to mention to maintain stability into all kinds of loads!! Uhh, a circuit with no feedback will be stable. Feedback is not used to provide stability. Instability is the result of incorrectly applying feedback. Negative Feedback can and is used to stabilize amplifiers - if you apply it in some ways, it certainly can make an amplifier unstable (such as use of positive feedback in regenerative circuitry) - negative feedback properly applied does make amplifiers more stable. You failed to understand that an amplifier with no feedback cannot be unstable. You were saying feedback was used to maintain stability. Local feedback may be something as simple as an emitter or source resistor. Yes - but I think they were talking about loop feedback, not ballasting resistors. Uhh, using emitter resistor or source resistor *is* applying feedback. You should be able to clearly visualize the feedback loop. Chung - you misunderstood what I was saying - the folks claiming "Zero feedback" most certainly mean they are not feeding back signal from the output to the input, but applying things like what we were talking about (ballasting resistors - on the source, or emitter to provide localized negative feedback is not taking the output signal and applying it to the input of an amplifier) But then why were you arguing with Mr. Platt? Please re-read what he wrote. He already said that some of these amps may very well have no global feedback, but instead have local feedback. |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
FS: AMPS $25 SPEAKERS $19 PAIR - FREE SHIPPING | Audio Opinions | |||
A Couple of questions on audioquest power cords and CD-Rs | Tech | |||
System warm-up | Audio Opinions | |||
AC Power Conditioner (Cont.) | High End Audio | |||
Matching ohmage to the ohmage output of your power amp | Pro Audio |