They Are 90k a pair?Someone told me that they’re $90k/pair. That’s more in line with their competition.
I wonder what the Ref 750 SE costs now.
Pre-Covid at an Paragon demonstration/education event I did enjoy some Audio Research paired with the elliptically shaped Sonus Faber's. First time for me actually enjoying the sound from either of them. Typically I'm not an Audio Research guy, but an old bias should never color opinions of a new product line in my opinion. I'm hoping to be wowed but not overwhelmed when I hear the 300M's.After researching extensively the 330M in preparation for interview with Dave Gordon yesterday, I think it is a very interesting amplifier!
It is a very interesting hybrid, with tube output stage, and tube input stage, and buffer and driver stages solid-state. Part of the power supply is tube regulated, and part of the power supply is solid-state regulated.
I look forward to professional reviews and to WBF members reporting on their experiences with this new amplifier!
Yes, tube input stage but buffered with "tube like" bipolar transistors. Last time I checked the transfer function of a bipolar transistor was radically different from a triode. Then to a differential tube stage and then to a JFET driver stage. That's a lot of stages. Then regulation. SS regulation for the small signal devices and tube regulation for the output stage! Normally, you would see it the other way around because to tube regulate such a high power amp means a lot of regulation devices and heat....not sure that this possible with 6 KT170s and only a single 6550 as a regulator tube. Something must be missing from this description.The circuit description indicates a pretty radically different design.
@morricab Astute you are... Indeed, you could read the literature by Audio research, it is described there, no 6550...Yes, tube input stage but buffered with "tube like" bipolar transistors. Last time I checked the transfer function of a bipolar transistor was radically different from a triode. Then to a differential tube stage and then to a JFET driver stage. That's a lot of stages. Then regulation. SS regulation for the small signal devices and tube regulation for the output stage! Normally, you would see it the other way around because to tube regulate such a high power amp means a lot of regulation devices and heat....not sure that this possible with 6 KT170s and only a single 6550 as a regulator tube. Something must be missing from this description.
Just looked at the specs:@morricab Astute you are... Indeed, you could read the literature by Audio research, it is described there, no 6550...
Silicon Carbide Jfets..They (AR) go on by saying...
"Using JFETs for drivers also allows each tube to be biased individually: each tube has its own servo."
Lets quote the whole thing, shall we...
"
The Reference 330M is unique, combining new thinking, new design, and new parts with the best concepts from other Reference amplifiers. The new front end is a hybrid, using an ECC83 tube rather than a JFET at the input. The ECC83 has a buffered output, the buffering accomplished with special bipolar transistors that have tubelike qualities.
The second stage is similar to the 610T and 250, with a differential pair loaded with a DMOS current source. Rather than using a 6550, the output tube drivers are new Silicon Carbide (SiC) JFETs, which give the driver stage more headroom. The output drivers are bootstrapped by the output (both in the drain and source), providing even more headroom during large signal swings, with reduced input capacitance.
Using JFETs for drivers also allows each tube to be biased individually: each tube has its own servo.
Output tubes are new KT170s, which have increased plate voltage margin, peak cathode current, and plate dissipation. They sound wonderful, with great musicality. In a properly designed circuit, the KT170 provides an elevated level of performance that is unequaled.
The power supply features solid state regulation for the front end and tube regulation (6H30 and 6550) for the output tube screens and driver stage. It also has a Pi filter using a large choke, reducing output stage supply ripple.
The 330M is a fully-balanced amplifier, from input to output. Operation is Pentode only because this offers the highest performance. The rear panel includes balanced XLR and single-ended RCA inputs, 8Ω and 4Ω output taps, 12V Triggers, RS-232 control, tube hour meter, 20A IEC, and fan speed adjustment.
In addition to the GhostMeter®, the front panel includes Power, Meter light adjustment, Tube Monitor, and a reduced voltage standby mode to preserve tube life while allowing quick startup.
The Reference 330M is not Audio Research’s largest amplifier, it is our best ever. The presentation is vivid, immediate, and relaxed at the same time, with a musical completeness. Bass extension, control and weight defy its topology. To experience music through the 330M is the only way to appreciate how it serves the performance."
Yup, that should do it ...
Yes...Just looked at the specs:
POWER OUTPUT
330 watts
TUBE BIASING
Auto-Bias
OUTPUT TAPS
4Ω, 8Ω
TUBE COMPLIMENT
(6) KT170 Power Output
(1) ECC83 & (1) 6H30 input
(1) 6550 & (1) 6H30 Power Supply
INPUTS
XLR & Single-Ended
CONTROLS
12V Triggers
RS-232 Remote Control
POWER SAVING
Standby Mode
WEIGHT
101 Ibs
Looks like it says there is a 6550 and a 6H30 in the power supply, no? Your bolded statement says something about the driver section. I only mentioned the 6550 as part of the power supply...
Just looked at the specs:
POWER OUTPUT
330 watts
TUBE BIASING
Auto-Bias
OUTPUT TAPS
4Ω, 8Ω
TUBE COMPLIMENT
(6) KT170 Power Output
(1) ECC83 & (1) 6H30 input
(1) 6550 & (1) 6H30 Power Supply
INPUTS
XLR & Single-Ended
CONTROLS
12V Triggers
RS-232 Remote Control
POWER SAVING
Standby Mode
WEIGHT
101 Ibs
Looks like it says there is a 6550 and a 6H30 in the power supply, no? Your bolded statement says something about the driver section. I only mentioned the 6550 as part of the power supply...
View attachment 133731View attachment 133732
The 330M's sounded real good, but so did the 160M MK2's for half the price. Going to depend on room size and speaker selection, and I suppose what you can afford.
No glaring shortcomings, strong bass and musical.
One observation or excuse for not having more praise is that I do NOT like box speakers in general, the Wilsons did their best in vain to convert me. However I know these speakers so gauging the amp's contribution is easier than with unfamiliar speakers - so there is that.
Good amps, Audio Research continues to improve and I admit that their products over a decade ago just didn't move me (flat & dry). Much has changed for the better, but the prices are well beyond my reach, and that falls on me I guess - gotta earn more.
One thing I do NOT know for sure is how to report the soundstage characteristics, or better known as; apparently nobody appreciates a strong center stage as much as I do, and they all want the stage as wide as possible no matter what.
With the loudspeakers so far apart I cannot tell you much about depth and imaging, and are confined to frequency response or just natural flow.
I was sitting in the first row of both rooms, just off center by one seat. No panning or phase issues.
Overall a better evening than with Octave Audio, bless their efforts but that mystery about "phase" or "out of phase" is an issue I'd like to see fairly resolved.
To be fair the Audio Research evening was plagued with two of the building's three A/C units going out on a hot evening, but everyone joked about it. And late in the Room-2 presentation some server sync issues kept Harry Belafonte from getting us on the Banana Boat (Day-O), but the good tunes kept playing.
People were in a good mood because good music can do that.
The 330M, going back to AR's roots with all 3-stages tube everywhere (no J-fets if I heard right), but with a 4-layer circuit board. Some discussion on tube swapping, sounded like you will want to stay with the Tung-Sol KT170's (long story).
EDIT: The pair of silver 330M monoblocks were heard at the event are now owned by Paragon and one would think are up for sale - someone asked if the rep's owned them. I have always thought of Audio Research products as a silver face, and these did not disappoint.
Ask Jeff Fischel about his 300 watt monoblocks (ART 300). He ships everything hard wired for 4 ohms. Having owned both CJ and ARC big monoblocks, I know that either 4 or 8 can be chosen, but one will sound more pleasing to most. Jeff will rewire on request.8/4ohm taps on such a powerful amp , Silly as they come ..!!!