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Monoprice Monolith 7-Channel Amplifier Review

by March 30, 2017
Monoprice Monolith 7 x 200 amplifier

Monoprice Monolith 7 x 200 amplifier

  • Product Name: Monolith 7-Channel Amplifier
  • Manufacturer: Monoprice
  • Performance Rating: StarStarStarStarhalf-star
  • Value Rating: StarStarStarStarStar
  • Review Date: March 30, 2017 00:00
  • MSRP: $ 1,499
  • Buy Now

Monoprice Monolith-7

  • Number of Channels: 7
  • EIA 1kHz Output Power at 8 Ohms:* 250 watts
  • EIA 1kHz Output Power at 4 Ohms:* 375 watts
  • FTC Full Bandwidth Output Power at 8 Ohms:** 200 watts
  • FTC Full Bandwidth Output Power at 4 Ohms:**     300 watts
  • Input Sensitivity for Full Rated Power: 1.6 volts
  • Frequency Response at Rated Output: 20Hz to 20kHz ±0.1dB
  • Phase Response: +5 to -15 degrees from 20Hz to 20kHz at 1 watt
  • Signal-to-Noise Ratio "A-Weighted": Greater than 120dB below rated FTC Full Bandwidth Power
  • Total Harmonic Distortion (THD): Less than 0.03% at full rated FTC power
  • Less than 0.005% at full EIA power at 1kHz
  • Intermodulation Distortion (IMD): Less than 0.03% at full rated FTC power
  • Less than 0.005% at full EIA power at 1kHz
  • Toroidal Transformers: 2 (1,230VA and 1,025VA)
  • Total Capacitance:156,800µF (22,400µF per channel)
  • Load Impedance: Safe with all types of loads
  • Rated for 4 to 16 ohms
  • Power Bandwidth: FTC +0, -3dB from 5Hz ~ 100kHz
  • Damping Factor: Greater than 400 from 10Hz ~ 100kHz
  • Crosstalk: Greater than 100dB from 20Hz ~ 20kHz
  • Gain: Voltage gain of 28dB
  • Slew Rate: > 50V / µS
  • Input Impedance: 28 kilohms (nominal)
  • Remote Trigger Voltage: 3.3 ~ 24.0 VDC at 5mA or greater
  • DC Output Offset: Less than ±5mV
  • Input Power: 120 VAC (nominal)
  • Chassis Dimensions: 17.0" x 7.0" x 16.5" (432 x 178 x 419 mm)
  • Net Weight: 93.2 lbs. (42.3kg)

All power ratings listed above and provided by Monoprice are measured with all channels driven.

* EIA 1kHz Power refers to maximum average power in watts at 1kHz with 0.005% THD and noise.

** FTC Full Bandwidth Power refers to maximum average power in watts from 20Hz to 20kHz with 0.03% THD and noise.

Pros

  • Astounding, real-world power that exceeds published specs
  • Incredible if not ridiculous value and price/performance ratio
  • Dual toroidal transformers ensure rated power with all channels driven
  • Truly tank-like build quality
  • Rigid binding posts and rear connectors
  • Trigger power on/off capability for integration with home automation

Cons

  • Really, really, really heavy
  • Confusing front power light
  • Front power light cannot be dimmed or defeated
  • + and - speaker terminals too closely spaced together
  • No balanced (XLR) inputs

 

Monolith-7 Introduction

We’ve all heard it before. “They don’t make amplifiers like they used to.” When someone utters those hallowed words, Krell’s name is inevitably invoked like a hallowed deity. The conversation then normally closes with a formulaic, “Big, heavy, and able to drive just about any speaker on the planet. Yeah, don’t make them like they used to.”

Well, if you’re nostalgic for those “good old days” of massive amps pumping out gobs of clean power then the time has come for deja vu all over again. I’m not talking about an amp costing upwards of $10K or $20K from a legendary audio company.  I’m talking about an upstart—a punk, for lack of a better word—that made its name selling HDMI cables (of all things) at a bargain basement price. That’s Monoprice.

Yes, Monoprice. Over the past year, Monoprice has made an immediate and aggressive move into the world of audiophile-grade equipment. In other words, audio that you’d use as part of a reference system.

Monoprice Monolith Amplifier YouTube Review

Designed & Engineered in the USA

I don’t know about you but I never would have thought about buying reference gear from Monoprice. It was exactly that notion that prompted this strategic focus.

Monoprice’s foray into high-end audio started as an idea towards the beginning of 2015. It was the brainchild of Hobie Sechrest, Monoprice’s Sr. Product Manager who convinced Monoprice’s then President Bernard Luthi, to bless the endeavor.

Monoprice Monolith-7 Front

Front view of the Monolith 7. When the Monolith 7 reaches full power, the front power button glows blue. 

There is no way to turn off the blue LED while the amp is activated.

It could have been easy for Monoprice to source its amplifiers from an overseas outfit, slap on their logo, and call it a day. However, Monoprice smartly realized that they needed some street cred for their amps if the were going to be taken seriously. To do so, they made (in my opinion) a brilliant move: they worked with US-based ATI.

ATI may not be a household name, but chances are you’ve either seen or heard an amplifier built by ATI.  Some of the most well-known companies (ie. Lexicon, Outlaw Audio, etc) in audio have either used ATI-designed amplifiers or had ATI build amplifiers to their specs.  Now you can add Monoprice to that list. According to Monoprice, ALL Monolith amplifiers are built in the same Montebello California based facility that ATI builds their other amplifiers too.

With ATI behind the scenes, it should come as no surprise that the Monolith is an absolute beast of an amplifier in size, weight, and power specs. In fact that’s what I nicknamed it shortly into my review period, “the beast.”

All Monolith amplifiers are Class AB topologies and share the same overall chassis, with the difference being the number of amplifier channels under the hood.  In my seven-channel review model there are two massive toroidal transformers capable of delivering 200 wpc with all channels driven into 8 ohms and 300 wpc with all channels driven into 4 ohms at full bandwidth.

What’s remarkable to me about all Monolith amplifiers (not just my seven-channel review unit) is the readiness and openness with which Monoprice provides specs.  With some companies you’re searching for certain measurements and they don’t provide them or you’ll find that they fudge some numbers by only driving the amp with two channels and measuring it at 1kHz. That’s not a completely accurate way to rate amp’s performance—regardless of what the so-called industry standard measurements are.

Monoprice Monolith 7 front LED light

The Monolith 7 front power button has a blue LED that illuminates once the amp is fully powered up. 

The light does not light up for the first 25 or so seconds while the amp is powering up, which can lead users to conclude incorrectly that the amp has malfunctioned.

Monoprice’s specs, on the other hand, are how we like to see them: with all channels driven and across the entire frequency band. Want to know the EIA 1kHz output power at 8 Ohms? 250 watts. How about 4 Ohms? 375 watts. Want to know the THD, intermodulation distortion, damping factor, crosstalk, capacitance, slew rate, phase response, signal-to-noise ratio, or the input sensitivity for full rated power? Monoprice gives you all that and more on their spec sheet. In other words, Monoprice hasn’t tried to hide a single number or measurement. Whether or not a manufacturer’s measurements can be corroborated is another discussion.

I was not privy to the results of our Audioholics measurements during my review period. Nevertheless, if my first-hand experience is any indication, I expect the Monolith to sail through all our tests in textbook style with flying colors and come right in line with their published specs. You can see Gene DellaSala’s notes and bench measurements, which he’ll be including later on in this review, for more info.

Build Quality Galore

If you have any doubts about the Monolith, cast them aside. Build quality is impeccable. The heat sinks on this amp are massive and integrated on the amplifier modules themselves inside the chassis.  There is no fan for cooling.

Even though the individual channels are on discrete amplifier modules, the Monolith models aren’t upgradable.  You cannot, for example, start with a two-channel model, and then ship it to Monoprice and add a few amplifier modules to upgrade to a five- or seven-channel version.

Top view of the Monoprice Monolith 7 Power Amplifier

Top view of the Monolith-7.  You can readily see each of the seven amplifier modules with their massive heat sinks.

To prevent tripping your breakers, the Monolith has a soft-start feature that gradually powers the amplifier up over a period of about 20-30 seconds. It’s a wonderful feature. My only complaint about this feature is that the Monolith’s front blue LED doesn’t light up immediately. When I first unpacked the amplifier and turned it on, I thought there was something wrong with it.  I don’t like the way this is implemented and I would suggest that Monoprice change the behavior of the LED from the factory so that it blinks when powering up and then turns solid when it reaches full operating power.

If Monoprice can’t make an adjustment to the LED, they would do well to include a tag on the amp or make a note in the user manual that the LED won’t light up until the amp has reached full power.  You can, however, play any source during that power up period without issue.

Editorial Note about Power LED

We didn't experience the delay in LED illumination for the Monolith-2 that we bench tested so this issue may only be limited to the 5 and 7 channel versions.

The Monolith has no current limiting circuitry so that if your speakers’ impedance drops, current won’t be limited like most AV receivers often do.  That’s not to imply that the amp will blow your speakers or get damaged if there’s a problem. There are monitoring circuits specially designed for this purpose. They are optically coupled and sit outside the circuit path. They’ll detect electrical shorts from your speaker wire or electrical outlet and disengage the amplifier’s output. The amp will then check the problem circuit every 10 seconds and restore power when things are clear.  Monoprice makes it a point to say that there’s no fuse or relay in the output, which can lower the damping factor and change the sound.

The five-way binding posts and RCA jacks aren’t fancy but they are incredibly rugged.  The RCA jacks are mounted directly to the chassis instead of a separate circuit board.  You can tell the difference immediately.  Plugging an RCA interconnect feels solid and stable. If you have stiff speaker cables, they also won’t start to bend the binding posts.

Monoprice Monolith 7x200 rear view

The Monolith 7 features unbalanced inputs and sturdy, high quality five way binding posts and a ground lug.  Channels are not bridgeable.

The only thing missing from this amp are unbalanced connections.


Oh, and legendary amps have heft, right? Well get ready for some serious exercise because the Monolith weighs in at a massive 93.2 pounds.  Yes, 93 pounds of solid, amplification muscle. To put that into perspective, the Monolith weighs more than my SVS Ultra Tower speakers. It weighs more than SVS’ SB13-Ultra subwoofer (by a hair).  So, if you have any intent of placing a Monolith amp in a rack or on an amp stand, double check to make sure they can hold this much weight.

Clarifying Compliance

The rear panel of the Monolith caused us some confusion that had to clarify directly with Monoprice. There are no compliance notices silk screened directly on the Monolith. The user manual (you can view a downloadable copy here) however, indicates that the Monolith 7 has FCC compliance. Moreover, the rear of the amp does not say it was built in the USA. It simply says designed and engineered in the USA. We confirmed with Monoprice that the amplifiers are made in Montebello, California. We can certainly understand cost savings and the like when building and branding a standard chassis.  However, in our opinion, we'd like to see Monoprice make both its FCC compliance and "Made in USA" silk screened onto the units themselves.

Set Up

The Monolith came impeccably packed. Due to its weight and especially its density, it’s very, very difficult to maneuver. Therefore, make sure you have help when you unpack it.

I tested the Monolith across a few different equipment configurations and it was an outstanding performer in each. I plugged the Monolith into a dedicated 20-amp circuit that is reserved solely for my home theater setup.

If you have dimmers in your house or the issue known as DC offset then the Monolith’s massive transformers may start to hum. They did in my case when the lights on my microwave were on and set to low.  To be clear, this isn’t a design problem with the Monolith. To fix the humming, I plugged the Monolith into Emotiva’s CM2 AC line restoration and common mode filter system. This two-outlet receptacle is specially designed to eliminate DC offset issues without limiting current or dynamics.

Detail view of the Monoprice Monolith's thick metal chassis.

Detail view of the Monoprice Monoltih-7's thick, vented, metal, chassis. You can see each amplifier through the generous vent holes.

When the amp first arrived at the tail end of 2016, I paired it with the superb-sounding Anthem AVM 60 preamp processor, our pre-pro of the year, where it powered the main channels of an 11.1.4 setup anchored by SVS Ultra speakers.

In the second setup, I paired the Monolith and Anthem with the RSL CG3 5.1 system that I reviewed

In the third pairing, I connected the Monolith to my Denon X7200WA AV receiver to drive the seven primary channels of my 11.1.4 Atmos and DTS:X setup.  I left the height channels to the Denon’s internal Class A/B Amplifier.  The speakers for this setup consisted of SVS Ultra Towers and Ultra Center. Ultra Bookshelves rounded out the surround and rear channels and Beale Street in-ceiling speakers served as height channels. An SVS SB13-Ultra subwoofer anchored the bass.

I used the Denon’s unified 11.1.4 layout with front and rear height assignments so that I could play Dolby Atmos, DTS:X, and Auro-3D titles interchangeably.

I’ve implicitly noted the Monolith’s performance as part of the Anthem AVM 60 and RSL CG3 reviews. Therefore, my comments below pertain to the Monolith, Denon, and SVS Ultra setup.

Confused about what AV Gear to buy or how to set it up? Join our Exclusive Audioholics E-Book Membership Program!

About the author:

Theo is a serious audiophile and home theater enthusiast—a passion he's enjoyed for over 20 years. He heads up many of our speaker system and receiver reviews as well as covering the latest in streaming technologies and Ultra HD video.

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Recent Forum Posts:

tparm posts on June 16, 2020 16:14
With Class D amplification being en vogue and ATI having success with their AT52XNC series, how long until there is a Class D Monolith variant? Thoughts? Insider info????
RichB posts on June 14, 2020 15:51
Pogre, post: 1397880, member: 79914
Boom! Thanks Peng!

I am going to conclude that scooting a little closer will definitely take a little heat off my speakers at high volumes. The folks over at Ascend have been a little bit hit and miss to contact lately, with everything going on but they always eventually get back to me. I think I'm gonna shoot Dave an email and ask him ask about max spl at 1 meter, like you suggested I do with Ed for my Ultras.

You know what's interesting, tho maybe not overly surprising? My Monolith runs MUCH cooler powering my 4 ohm Sierra towers than it does my “8 ohm” Ultra towers. It's gets good and warm with the Ultras, but barely more than lukewarm with the Sierras. Even after some some very spirited listening sessions.

In general, when you consider stereo and room gain the volume at the listening position can be surprisingly close to rating at 1 meter (when accurately specified).
Ascends are among the best manufacturers at accurate sensitivity specifications.

Here is recent article on Audio Science Review:
https://www.audiosciencereview.com/forum/index.php?threads/speaker-sensitivity-advertised-vs-measured.14072/

Adding power to speakers that perform will with power (with good distortion characteristics) can lead to listening at higher levels. A small radio can seem too loud because the distortion is makes it unpleasant. That said, I have found I enjoy my Salons for casual listening at less than one watt. Of course, I'd like a near perfect 1'st watt

THX specifications are for a single speaker but this is not representative of any realistic listening session.
To estimate my power usage I used the following procedure.

I played 250Hz, 1kHz, and 2kHz 0 DBFS (maximum volume) sine-wave tones and measured the voltage at the speaker adjusting the processor until it was as close as possible to 2.83 volts. The volume matches the speakers sensitivity rating. While playing the tone, I measured the SPL at my listening position of 11 feet.

The Salon2s are rates are 86 dB at 1 meter. The measured SPL was also 86 dB (with two speakers playing). The Salon2s are basically 4 ohm speakers that doubles to power. For my spreadsheet, this means -31 is 86 dB at 11 feet. From there I computed the attached power levels. Since I know my habits, the left column indicates those levels. Fortunately, the AHB2 amplifiers have accurate and clip meters per channel that illuminate for 1/4 seconds when the amp hits 1% distortion.
With music, they clip as expected with recording that peak at full scale (too many recording are maximized for volume).

Into 4 Ohms, the AHB2s deliver 180 WPC and they are not clipping at -10 so these numbers are conservative.
I also plugged in these numbers into the Crown power calculator: 3.5 meters, 101 dB, 83 dB sensitivity (for 4 ohms) and the required power is 773 watts.
My measurements and calculation show 64 watts stereo or 128 watts for a single speaker.

37113
37114

The Aquaman 4K BD has some formidable bass and I turned it up -15 (which is 3 dB louder than I found comfortable) and there is no clipping and the Salon2 3 8 inch woofers are really moving.

Unfortunately AVR amps are seldom measured as diligently as dedicated power amps and not going into protection is not a good indicator of distortion driving reactive loads. Those measurements don't really exist. We know a lot about how amps play 1 kHz sine-waves into reactive loads.

- Rich
operamatt posts on June 14, 2020 08:31
Verdinut, post: 1397824, member: 80194
Those Monolith amplifiers are really well designed affordable amplifiers. You won't regret your purchase.

Are you an opera nut too? Because of my user name, it's not hard to guess who is my preferred Italian composer. If that is the case, maybe we could exchange comments at some point. In my collection, I have the complete Verdi Parma Opera series on Blu-ray, apart from all his operas on CD. That's only part of my opera collection.

I know quite a bit about opera singers and I am very critical about them. I studied classical singing. As a lyric tenor, I used to sing solos with choirs, and also sung in restaurants as a hobby. It was indeed a passion.

Cheers!
very cool, i also trained as a classical musician. my mane instrument was voice but i was a pianist & director as well. i’ve chosen a different path for my life but the love for classical music is still there.
PENG posts on June 13, 2020 09:23
Pogre, post: 1397880, member: 79914
Boom! Thanks Peng!

I am going to conclude that scooting a little closer will definitely take a little heat off my speakers at high volumes. The folks over at Ascend have been a little bit hit and miss to contact lately, with everything going on but they always eventually get back to me. I think I'm gonna shoot Dave an email and ask him ask about max spl at 1 meter, like you suggested I do with Ed for my Ultras.

You know what's interesting, tho maybe not overly surprising? My Monolith runs MUCH cooler powering my 4 ohm Sierra towers than it does my “8 ohm” Ultra towers. It's gets good and warm with the Ultras, but barely more than lukewarm with the Sierras. Even after some some very spirited listening sessions.

I just clarified my comments a little, but we were typing at the same time.

The Ascends are likely more sensitive and have better phase angles than the Ultras. I discussed power requirements with Ed before, you (may be not you but people who think amps are always needed for 4 ohm speakers) will be shocked if you know what he said..
Pogre posts on June 13, 2020 09:18
PENG, post: 1397878, member: 6097
Okay then, the Ascends in your system will still be the bottleneck as it is only rated 500 W maximum short term peak. You will need about 660 W to hit reference level with one speaker from 15 feet.

The Monolith can output only a little more than 500 W average short term dynamic peak, that's 1,000 W peak, two channel driven into 4 ohms.

Calculated results based on Ascend specs, for one single speaker:



Input data required:
Input data
Unit


1) Speaker nominal impedance (Ohms)
4.00
Ohm


2) Sensitivity in dB/W at 1 Meter


dB


3) Sensitivity in dB/2.83 V at 1 Meter
90.00
dB


4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)
4.57
Meter


5) Room gain for speaker placement near walls/corners, enter 0 to 3 dB max., to err on the conservative side
3.00
dB


6) Desired additional amplifier headroom (dB) Recommended minimum is 3


dB


7) Target SPL - THX reference is 85 dB, with 20 dB of headroom
105.00
dB









Calculated values from the input data:
Calculated values



Sensitivity loss at seating distance (dB)
13.20
dB


SPL/W at seating distance calculated from the input data
79.80
dB


Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter
2.00
Watt (W)


Power increase in multiples needed to achieve target SPL
331.46



Power increase in dB needed to achieve target SPL
25.20
dB









Calculated amplifier output power required:





For the target SPL at seating distance
663.66
Watt (W)


For the target SPL at seating distance, with the desired headroom included


Watt (W)


Boom! Thanks Peng!

I am going to conclude that scooting a little closer will definitely take a little heat off my speakers at high volumes. The folks over at Ascend have been a little bit hit and miss to contact lately, with everything going on but they always eventually get back to me. I think I'm gonna shoot Dave an email and ask him ask about max spl at 1 meter, like you suggested I do with Ed for my Ultras.

You know what's interesting, tho maybe not overly surprising? My Monolith runs MUCH cooler powering my 4 ohm Sierra towers than it does my “8 ohm” Ultra towers. It's gets good and warm with the Ultras, but barely more than lukewarm with the Sierras. Even after some some very spirited listening sessions.
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