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AM 833M New completely revised for 2021

Simply awesome integrated power supply version of the 833S.  Stunning sonics in a more manageable size.  130W/ch, Pure Class A, Single Ended. 

 

Price: Please contact us for world beating pricing on this special product.                  
                         

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The Silver version uses a square section pure silver, 24 carrot gold wiring in all crucial signal paths and in the umbilical cord from the power supply. The copper version is no longer available.

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Despite the towering performance of the 833S, the all conquering Flagship Model, there was a definite need for a model in between the 833S and the 805M. So he set to work to make a single chassis version of the 833S because the only drawbacks to this amplifier was that although a screaming bargain compared to its extraordinarily expensive competition, it was still relatively expensive (especially in any other market where the price is double here), it was large, and very heavy.
The result of this is the quite extraordinary 833M. The power supply is still quite mammoth, and is still huge compared to other amplifiers who attempt to compete. The amplifier design between the two is mainly the same. 
The performance between the two is surprisingly similar. They share the same awesome tonality, huge soundstage, dead silent background and incredible ambience. The bass control is exceptional, but the 833S has that little bit more and even better bass control and performance. But compare them to any other amp. The other amps become boring and unlistenable. 

 

 

* The AM 833M is an absolute state-of-the-art, no compromise designed originally to celebrate AM's 12th Anniversary.  This is a heavily revised version for 2021.

* Both the amplifier and the power supply sections are isolated to reduce magnetic field interference from the two massive double C HIB power transformers, thus ensuring that only pure power is supplied to the amplifier.

* The signal circuit is direct coupled and transformer coupled, eliminating capacitors from the signal path to avoid any compression of the dynamic range.

* The multiple independent power supplies use an effective ?-shaped filter circuit for exceptional noise isolation.

* All the tube heaters use silicone-diode rectification. The -shaped filter coke transformers are DC coupled to a large volume condenser to minimize hum.

* Both the drive and output transformers both use a very complicated winding technique and are constructed of special magnetic materials so that a bandwidth of 10Hz- 120KHz. is achieved.

* The 833 tube sockets are machined from Teflon, and use gold plated phosphor bronze round pins for an exceptional contact and improved sound quality.

* The internal wiring is either silver or a special customized rectangular OCC copper wire which was carefully chosen over a long period by extensive listening.

* The chassis is constructed of a very thick aluminum alloy, precisely machined by precision CNC machinery to ensure it is very strong, stable and reliable.

* It is this attention to detail and lack of compromises that result in an exceptionally musical and stunningly clear sound reproduction.
 

 

Data specifications:
 

 

 Power Tube: 833

 Tube complement: ECC88 as the drivers, KT150.  As the amplifiers . 833

 Frequency response: 20Hz-100KHz

 Input Impedance: 100k ohms

 Input Impedance: 100k ohms. 1.0Vrms

 S / N: > 95dB

 RCA single-ended ; balanced / XLR

 Power Output: 120w

 Load impedance: 4 & 8 ohms

 Power consumption: 400W(each)

 Power supply: 100,110,120,220,230,240 VAC 50-60Hz

 Dimensions: 289 X 487 X615  (mm)

 Weight: 63kg X 2

 

Customer feedback Review of Audio Music RT2 Pre-Amplifier and Audio Music 833M SET Mono Block Amplifiers.

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I have been into audio for over 45 years, starting with a Yamaha receiver in the 1970’s and an old set of satellite speakers from my parents with a cheap vinyl rig. I have owned solid state amplifiers from GAS (Ampzilla), David Halfer solid state kits, Parasound gear and Krell gear.

Speakers have included: Bose 901s (good party speaker for uni!), Cambridge Audio Transmission Lines, Rogers LS35A with Dahlquist Subwoofer, Allison AL125 Floorstanders, VAF Sig I66

My first foray into valves was a Chinese KT88 integrated that sound pretty good but soon failed. I loved the sound of valves so much that I then purchased my first big triode amplifier, a set of Jolida 211 mono-block amplifiers pushing 150 watts. They sounded fantastic but were unreliable. I rebuilt the Jolidas and sold them.

I then built a set of Dynaco clone KT88 mono-blocks, which sound really good, but missed the triode magic. This brings me to my current amplifiers from Audio Music, the RT2 Pre-Amplifier and 833M SET Mono Block Amplifiers.

I purchased the AM units from Greg at Osborn Loudspeakers after a lengthy telephone conversation. Greg is very knowledgeable and very easy to deal with. It has been a pleasure doing business with him.

After 125 hours of burn in of the Audio Music pre and mono blocks sound excellent. They do need burn in to sound their best – not sure if this is related to the coupling caps (Audio Music’s own manufacture – m Caps: beryllium copper foil / polyester film) in the pre-amp or the transformers (volume control, coupling and output).

My System:

  • Room (small - 3.1m x 3.5m x 2.4m) - Your room is one of the main components of your sound system – a great sounding system can sound terrible in a bad room. Acoustic Treatments in my room include:

    • DIY Bass Traps in the 4 corners.

    • DIY Quadratic Diffusers on ceiling .

    • DIY Argent Room Lenses (3 off with 5 pipes each rather than 3 as in the original design).

    • DIY Sound Adsorption Panels on the rear wall behind the listening position.

    • Thick wool carpet on floor.

    • CD Racks on side wall acting as diffractors.

 

  • Audio Music R-T2 preamp: Class A, two 6H6Pi valves as drivers, two 6H6Pi valves as amplifiers. Dual mono design - transformers, power supply and voltage regulation are completely separated. The AM R-T2 utilise 33 step transformers for volume attenuation plus another 2 transformers for the signal output and two more for power supplies. Silver wiring throughout.

 

  • Audio Music 833M mono block power amplifiers: 120 watt Class A SET. ECC88 as input / KT150 as driver / 833 C as amplifier. The signal circuit is direct coupled and transformer coupled.

 

Multiple independent power supplies use p-shaped filter circuits. All tube heaters use silicone-diode rectification. The internal wiring is either silver or a special customised rectangular OCC copper.

 

  • Oppo BD105 SACD Player.

 

  • VAF i66 Signature MKII speakers (3 way / 6 ohms nominal / 89dB @ 2.83V @ 1m).

 

  • Cables:

    • JungSon Balanced – SACD to pre-amp.

    • Transparent Music Link Plus single ended – pre-amp to power amps.

    • Origin Live Advance Bi-Wire Speaker Cables.

 

  • PneumaticPlus Anti Vibration Pads under Electronics.

 

  • Carroll & Meynell Variac + Consonance PW-1 mains filter .

 

  • Siesta-Lab OFC-029 Power Chords.

Build Quality:

Audio Music equipment is built like the proverbial Brick Outhouse. They are extremely well finished. Interior pictures show impressive wiring & assembly details. The pictures of the pre-amp interior show audiophile Japanese Nichicon Electrolytic Capacitors. Based on weight alone there is a lot of “iron” (transformers) in the components. (Pre-amp: 2 boxes @ 35kg total / Mono blocks: each @ 63kg)

The 2 modules in the pre-amp alone weigh more than my previous pre-amp (MingDa MC-7R) and mono-block power amps (Tubes4HiFi M125s) together.

The 833 transmitting triode valve is huge! When I first received the amps, I thought that I had red-plated the power tubes as they were glowing a dusty pink orange. I have found out since that this is perfectly normal operation.

The amps are rock steady – tube bias has changed ever so slightly in the two months that I have had the amplifiers.

Sound Quality:

Dynamics: The system can go from inky black silence to extreme levels and back without missing a beat. I have jumped due to the sudden increase in sound pressure levels with some recordings. When required, power is always on tap. I had my sound pressure meter out one day when the sound level jumped from 85 dB to 113 dB in an instant!

Bass: The bass response is phenomenal! It is “phat” and bass lines are very easy to follow in the mix. It reminds of when I had Krell amplification. The bass seemed to go down another half octave.

Mid-Range: Lush and sweat. Easy to follow lyrics and understand the words.

Highs: Detailed and airy. Cymbals shimmer.

Tone and Timbre: A piano sounds like a piano. Guitars sound like guitars. The Music Audio equipment faithfully reproduces what is on your source. I was listening to the Naim CD of the Antonio Forcione Quartet “Live in Concert.” Antonio changes between nylon and steel stringed guitars throughout the show. You can easily tell which guitar he is playing. The percussive nature of his playing shines through along with the resonance from the guitar body.

On Vanessa Fernadez’s SACD “Use Me” you can hear the thwack of the stick hitting the drum skin.

Transparency: Very transparent with lots of air – can pinpoint instruments in the sound stage when the recording dictates. I know it sounds cliché, but I am hearing things in recordings that I have not heard before. This could be due to listening more closely with the new setup and picking up these details.

Soundstage: Extends behind, in front, above and to the sides of the speakers when the recording dictates. There is an Opus 3 SACD of Tiny Island. When the Vaquero track starts there is a rain stick that can be heard directly to the right of the listening position that then moves to rejoin the mix between the speakers.

Tube Rolling:

Due to the transparency (and I think the quality of the small signal valves installed in the 833M) less than perfect recordings are less than perfect. There is small degree of upper register sibilance and harshness present.

But good recordings are unbelievably good. Listening to Patricia Barber’s MoFi SACD Companion you are in the audience at the Green Mill.

The mono blocks have W German made 6922 Amperex labelled valves which are not as sweet as the US or Dutch 6922 valves. (The W Germany indicates that the valves were later production.) Amperex made 6922s in Holland and the US, so not sure who made these valves. They were probably made as an OEM for Amperex when vavles were being replaced by transistors. They are not a bad valve, but my hearing is sensitive to sibilance and harshness. I prefer Dutch or American Amperex 6922 valves.

The RT2 has Russian NOS 6H6Pi valves installed, which are supposed to be excellent. And from my experiences they do seem to be very, very good valves.

http://www.lampizator.eu/UPGRADE/upgrade%20noval%20tubes%20to%206H6P.html

I have installed a matched, balanced pair of 1965 NOS US Amperex 6922 PQ, white label, gold pin valves in the 833Ms.

After 15 hours of burn of the new valves we are cooking with gas! The valves still have a way to go before they are fully cooked. But even without full burn in the sibilance and harshness has all but gone. The midrange is glorious, with just the right amount of warmth. The top end sparkles, and the sound is very detailed.

That triode magic is there!

Music decays into a black background when the recording has it present. There is no grain to the sound. Timbres and tones are natural and sweet.

I was listening to the Japanese blue spec CD of Janis Joplin “I Got Dem Ol' Kozmic Blues Again Mama!” On Little Girl Blue you hear and feel the anguish in Janis’ voice.

I have had a lot of high end equipment in my system over the years. Without a doubt the Music Audio equipment is the best I have ever heard in my system or in any other system for that matter. And the units that I purchased are middle of the line from Music Audio! These will be the last pre-amp and power amplifiers that I ever purchase. They are truly “Hi-End”.

Review by Peter G

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