... και τελικός ενισχυτής από τη Benchmark

[Costas Coyias]

Από τα πλέον ενδιαφέροντα email που έχω λάβει εφέτος. Μετά από 30ετή πορεία, η Benchmark λανσάρει τον πρώτο τελικό ενισχυτή της. Ως φαίνεται στις σχετικές φωτό, το πλάτος του σασί του είναι ακριβώς το ίδιο με τους dac της, ενώ ένθεν και ένθεν εξέχουν ευμεγέθη ψυγεία - άρα ο ενισχυτής είναι γραμμικός. Οι προδιαγραφές αναφέρουν ισχύ 100W και 340W σε γεφυρωμένη λειτουργία.

Το σχετικό άρθρο περιλαμβάνει και μια δυσάρεστη είδηση, καθώς ο Allen Burdick, ιδρυτής και ιθύνων νους της Benchmark έως το 2006, που συνταξιοδοτήθηκε, ξεκίνησε το μεγάλο ταξίδι στις 27 του περασμένου Σεπτεμβρίου.

http://www.benchmarkmedia.com/power-amplifier/ahb2

 

[ep4nder]

Τί είναι αυτές οι "νέες" τεχνολογίες δηλαδή που γράφει στο άρθρο? "...THX recently patented two new technologies that address crossover distortion, and Benchmark incorporated these innovations into the AHB2 design. These new innovations virtually eliminate crossover distortion while offering opportunities to improve efficiency, damping, and dynamic range. The licensed technology solves the crossover problem by combining a plurality of output stages such that one stage drives the output while another stage enters a crossover region. Distortion performance exceeds that of class A amplifiers, while the efficiency exceeds that of traditional class AB amplifier".

 

[Costas Coyias]

Έλα ντε...

 

[anemelos]

Όποιος επείγεται να καταλήξει σε συμπέρασμα, μπορεί να το εκλάβει σαν marketing innovation technology! Μέχρι να φανεί τι πσάργια πιάνει ο ενισχυτής στην πράξη, οπότε τα συμπεράσματα θα είναι πιο αντικειμενικά.

 

[VasilisM.]

Έλα ντε...

Δώσε πληροφορίες...!

 

[Yiannis_B]

http://www.stereophile.com/content/high-efficiency-non-switching-amp-thx

When playing a full-power sine wave, Class D amplifiers are more efficient, he noted, but in real-world conditions when playing even the loudest music, the average power of a Class D amp will only be about 10 percent of the maximum sine wave power, so the efficiency for both Class D and the THX amp technologies will be both closer to 30 percent, he explained. At lower listening levels, the THX technology becomes much more efficient because its standing dissipation is much lower, typically1/20th that of a Class D amplifier, Fincham said.

Standby power consumption is extremely low, he added. “When it does nothing, it takes nothing.”

The cool-running technology suffers “none of the radio-frequency emissions problems that plague most digital amplifiers,” making it especially suitable for automotive applications, the company added.

http://www.twice.com/news/thx-demos-high-efficiency-analog-amp-technology-0

http://www.stereophile.com/content/high-efficiency-non-switching-amp-thx

 

[Costas Coyias]

...άρα αυτά που αναφέρει η Benchmark εφαρμόζονται στην τροφοδοσία, που παράγει πλήρη ανόρθωση με ημίτονο + συνημίτονο. Όχι στο κύκλωμα ισχύος...

 

[Yiannis_B]

Μοιάζει να δουλεύει ως εξελιγμένος class H με μεταβλητό Vrail που ακολουθεί το σήμα εισόδου. Στην θετική ημιπερίοδο του σήματος, το αρνητικό Vrail = 0V. Το αντίστοιχο συμβαίνει στην αρνητική ημιπερίοδο. To basic voltage (σχήμα 2) σε αυτή την περίπτωση είναι 0. Χωρίς σήμα τα Vrail μηδενίζονται.

http://en.wikipedia.org/wiki/Amplifier#Class_C

Σχήμα 1: Class H

Σχήμα 2 : Class H:

 

[delamostre]

@ [URL='http://www.avsite.gr/forum/members/vasilism.4445/']VasilisM.[/URL]
Δηλαδή εσύ τι κατάλαβες τώρα κι έβαλες like?
Tην αρνητική ημιπερίοδο ή τη θετική?

 

[VasilisM.]

Καλά θα του το αφαιρέσω τότε .... (εσένα το μυαλό σου στην ημιπερίοδο...)

 

[deleted user 10898]

I will be at the AES 2013 show in NYC and would be happy to discuss the new technologies incorporated into this new amplifier. For those of you who will not be attending the AES show, I will attempt to outline the engineering decisions that went into the AHB2.

It was my goal to create a power amplifier that matched the performance of the DAC2 D/A converter. After all, the performance of the D/A converter is only useful if it can be delivered by the downstream power amplifier.

In many ways, the AHB2 is a radical departure from conventional class AB amplifier design:

1) Low gain (9 dB) - allows +22 dBu input at amplifier clip - essential for low noise
2) Patented feed-forward error correction - virtually eliminates crossover distortion
3) Feed-forward design makes bias currents unnecessary, and non-critical - class B operation is possible with very low distortion
4) Multiple output stages run in parallel to eliminate crossover distortion - one output stage is active while another is in the crossover region
5) Class AB output stage uses very low bias current
6) Due to low bias currents, idle power consumption is only 20 W
7) Feed-forward design makes class H or G operation possible - no rise in distortion at class H or G switch point
8) Class H (or G) rail switching at a 1/3 power threshold
9) Tightly regulated power supply
10) High-bandwidth control loop on switch-mode power supply responds to amplifier loading over the entire audio band, and at ultrasonic frequencies
11) Amplifier does not rely on capacitive energy storage
12) Switch-mode power supply eliminates AC line magnetic interference to levels that are not possible with a linear power supply
13) >200 kHz bandwidth to achieve excellent inter-channel phase at 20 kHz.
14) < 0.1 Hz low frequency cutoff to minimize low-frequency phase shift
15) Feed-forward design improves damping factor

The AHB2 design was optimized for low distortion and low noise. It was not optimized for the highest possible efficiency that can be achieved with this new topology. Nevertheless the AHB2 is much more efficient than a conventional class AB design. Peak power does not vary with AC line voltage (due to regulated supply). Power drawn on one channel does not influence the power available from the other channel.

The AHB2 is a linear amplifier, it is not a switcher. For this reason, it produces very little out-of-band noise. A-weighted noise is only 2 dB less than noise measured over an 80 kHz bandwidth. This was an important design goal because ultrasonic noise can be folded into the audio band by non-linearities in speaker transducers.

If you have more questions, talk to me at AES, or post questions here.
__________________
John Siau
Gear Builder

VP Engineering

Benchmark Media Systems, Inc.
www.benchmarkmedia.com
Gearbuilder(Answers | This Thread)

 

[Yiannis_B]

1) Low gain (9 dB) - allows +22 dBu input at amplifier clip - essential for low noise

= 10Vrms, ή 28Vp-p η έξοδος του pre...

As far as pricing, I have read that it is not yet finalized but they are trying to keep it as low as possible and it will be under $3,000.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1381788695&openflup&7&4#7

 

[Gkat]

μια αναφορα στον παραπανω ενισχυτη απο την εκθεση CES 2014 που γινεται τωρα εδω...

δεν ειναι κανονικο review...

πηγη ενα mac mini, Benchmark dac και ηχεια KEF...

οπως λεει ο τυπος, ο ενισχυτης ακουστηκε πολλα υποσχομενος...πολυ ησυχος, δυναμικος και μουσικος...

δε λεει βεβαια αλλα στοιχεια...διαφημιση ή review δε ξερω να σας πω...