Monoprice Monolith 7-Channel Amplifier Review

[lovinthehd]

Never saw geoffreythegeek's calculator before but it does say it builds in 3dB headroom so that's double the power right there over what the other calculator would indicate. I didn't play with it, tho.

Music spl can also be hard to judge by the master volume calibration, which is more geared to movies made with a standard in mind. Source device level can be part of it, too. Generally if you're getting good audio at the levels you use the Marantz at, sounds like you're fine without an external amp, but if you want that bit of extra capability.....

ps Now see your comments about sometimes more elevated levels and that you also use an spl meter....

 

[buckchester]

For the homestead calculator I always figure away from walls. You know how loud 96 db is? That's really freaking loud. If you think you need more spl a better approach would be more sensitive speakers.

I would agree that if I'm listening to music and the average volume is around 96db, that is very loud. I don't normally listen that loud (sometimes I do ). But it's not nearly as loud for dynamic peaks, especially in movies. During loud dynamic peaks in movies, I think I've measured around 105db at my listening position, which is very loud, but not over-bearing by any means. And I get the sense that a lot of that sound power is coming from the subs because the dbs really only rise to those levels when there is a TON of bass. Bass frequencies at those levels aren't as loud on the ears as midrange or treble peaks from the speakers.

I'm not really sure what my target spl should be for these speakers at my listening position, Like I've said, my Marantz seems to be able to drive the Revels to sound pretty loud, but at the loudest levels I sometimes like to listen to, it can sometimes sound harsh. And whether that's do to it simply being too loud, or due to my receiver running out of power and making the speakers should more shrill than they otherwise would with a better amp, I don't know.

 

[PENG]

The speaker that is close to the wall is about 2 feet from the side wall, and about 3 feet from the back wall. The speaker that is far from the wall is about 6 feet from the side wall, and about 4 feet from the back wall.

Can you elaborate on your second point? If the trim is at +2.5, why do you think it would sound harsh at -15? And why would you recommend below -20?

Based on everything I've said, do you have a sense as to whether or not you think I would benefit from the Monolith amp?

If you give me your distances from the F208s and I'll do a better calculation for you, instead of guessing.

 

[Pogre]

If you give me your distances from the F208s and I'll do a better calculations for you, instead of guessing.

Yes! I'm curious myself.

I understand wanting to turn it up sometimes and can get a little nutty with the volume. Depending on sensitivity, distance and impedance you might be a candidate for an amp. I think I've pushed volumes that would tax my avr with my Ultras.

 

[buckchester]

If you give me your distances from the F208s and I'll do a better calculation for you, instead of guessing.

My listening position is 10 feet from the speakers.

 

[lovinthehd]

There's also the idea of simply taking work away from the avr to an extent, and running things a bit cooler. Altho an external fan for an avr isn't a bad idea either....

 

[PENG]

My listening position is 10 feet from the speakers.

Thank you, given the information, based on a conservatively estimated room gain of 3 dB, if you are happy with 80 dB average, 100 dB maximum peak then you only need about 1.3 W average and 130 W for the maximum dynamic peaks found on THX movies.

Calculated results based on target SPL of 80 dB average and 105 dB peak:

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	88.50	dB
4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)	3.05	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	100.00	dB
Calculated values from the input data:	Calculated values
Sensitivity loss at seating distance (dB)	9.68	dB
SPL/W at seating distance calculated from the input data	81.82	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	65.80
Power increase in dB needed to achieve target SPL	18.18	dB
Calculated amplifier output power required:
For the target SPL at seating distance	131.75	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

For reference level, that is, 85 dB average, 105 dB peak, you would need 417 W, again that's with one speaker playing. For two speakers, and the same target SPL, the power required will be less than half, that is, the 200 W Monolith amp will be more than enough.

For THX movies such as many on BR discs, your volume position would be at around -5, but with trim at +2.5, it would effectively be at about -2.5 when listening to 80 dB average with peaks to 100 dB.

That is based on just one F208, no subwoofer. For stereo music it would feel more like 83-85 dB, that's almost reference level, when both speakers are playing practically simultaneously most of the time. Or for the same 80 dB SPL average the volume position could be lowered to about -8 to -10.

At such level, I don't expect audible distortions causing harshness except if the music media content has very high dynamic range, then you may hear distortions during those high peaks.

Here's a database if you are interested to know whether you have some of those albums.

Album list - Dynamic Range DB

It is quite possible that the harshness came from the media contents you listened to. Given what you have now, sound quality would likely be mostly determined by the recording quality, not your AVR and/or amps.

If you must listen to reference level, that is 105 dB peak without using subwoofers then you should get a Monolith 200WX5 and biamp the F208s, or just get a more powerful amp.

So the thing about whether you need an amp, and how powerful an amp you need, largely depends on your seating distance, desired SPL, nominal impedance of the speakers and most importantly, the sensitivity of the speakers.

Regarding the trim, I think I explained it, but let me know if that's still not clear.

 

[Pogre]

Okay Peng, now do mine!

Speakers 2' from front wall and 2' or more from side boundaries.
MLP 15'
87 db @ 2.83v for the Ultras (published 8 ohm, but gene found them to be 6 ohm speakers I think, if not 4 ohm...)
90 dB @ 2.83v for the Sierras (4 ohm)

And, if I'm not already being a pain, how much would I gain moving a foot or 2 closer?

 

[PENG]

Okay Peng, now do mine!

Speakers 2' from front wall and 2' or more from side boundaries.
MLP 15'
87 db @ 2.83v for the Ultras (published 8 ohm, but gene found them to be 6 ohm speakers I think, if not 4 ohm...)
90 dB @ 2.83v for the Sierras (4 ohm)

And, if I'm not already being a pain, how much would I gain moving a foot or 2 closer?

To find the room gain if you have do some measurements. I'll just assume the same conservative number of 3 dB and the result is, 883 W (663 W if 2 ft closer) based on 6 ohms for one single Ultra speaker to produce 105 dB at you mmp that is 15 ft from the speaker. That requirement would drop to only 70 W (52.7 W if 2 ft closer) if you based on target spl 100 dB, 6 dB room gain, and 2 speakers playing simultaneously. Now you know why I used the word "depend" so often.

Input data required:	Input data	Unit
1) Speaker nominal impedance (Ohms)	6.00	Ohm
2) Sensitivity in dB/W at 1 Meter		dB
3) Sensitivity in dB/2.83 V at 1 Meter	87.00	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	76.80	dB
Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter	1.33	Watt (W)
Power increase in multiples needed to achieve target SPL	661.36
Power increase in dB needed to achieve target SPL	28.20	dB
Calculated amplifier output power required:
For the target SPL at seating distance	882.79	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

You should be able to get the same results if you use that homestead myhometheater calculator, except as you know it is based on 8 ohm impedance, so you have to adjust the result one way or another, in order to match mine.

 

[buckchester]

Thank you, given the information, based on a conservatively estimated room gain of 3 dB, if you are happy with 80 dB average, 100 dB maximum peak then you only need about 1.3 W average and 130 W for the maximum dynamic peaks found on THX movies.

Calculated results based on target SPL of 80 dB average and 105 dB peak:

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	88.50	dB
4) Seating distance (1 foot = 0.3048 Meter, 1 Meter = 3.281 foot)	3.05	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	100.00	dB
Calculated values from the input data:	Calculated values
Sensitivity loss at seating distance (dB)	9.68	dB
SPL/W at seating distance calculated from the input data	81.82	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	65.80
Power increase in dB needed to achieve target SPL	18.18	dB
Calculated amplifier output power required:
For the target SPL at seating distance	131.75	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

For reference level, that is, 85 dB average, 105 dB peak, you would need 417 W, again that's with one speaker playing. For two speakers, and the same target SPL, the power required will be less than half, that is, the 200 W Monolith amp will be more than enough.

For THX movies such as many on BR discs, your volume position would be at around -5, but with trim at +2.5, it would effectively be at about -2.5 when listening to 80 dB average with peaks to 100 dB.

That is based on just one F208, no subwoofer. For stereo music it would feel more like 83-85 dB, that's almost reference level, when both speakers are playing practically simultaneously most of the time. Or for the same 80 dB SPL average the volume position could be lowered to about -8 to -10.

At such level, I don't expect audible distortions causing harshness except if the music media content has very high dynamic range, then you may hear distortions during those high peaks.

Here's a database if you are interested to know whether you have some of those albums.

Album list - Dynamic Range DB

It is quite possible that the harshness came from the media contents you listened to. Given what you have now, sound quality would likely be mostly determined by the recording quality, not your AVR and/or amps.

If you must listen to reference level, that is 105 dB peak without using subwoofers then you should get a Monolith 200WX5 and biamp the F208s, or just get a more powerful amp.

So the thing about whether you need an amp, and how powerful an amp you need, largely depends on your seating distance, desired SPL, nominal impedance of the speakers and most importantly, the sensitivity of the speakers.

Regarding the trim, I think I explained it, but let me know if that's still not clear.

Thank you so much for all this information. Please let me know if I am understanding you correctly:

I should be able to get approx. 80db average , 100db peak (content dependant) with my Marantz receiver alone and it would be set between -10 to -8 volume?

I should be able to get approx. 85db average, 105db peak with the Monolith amp and the volume would be set to -5?

Some other comments:

I rarely ever listen to the volume higher than -10, so does this mean that perhaps my Marantz receiver is more than adequate for my current listening levels.

I noted you mentioned a few times that the numbers you mentioned are without a sub. I actually have two PSA v1500 subs, and the speakers are crossed over at 80hz.

 

[Pogre]

To find the room gain if you have do some measurements. I'll just assume the same conservative number of 3 dB and the result is, 883 W (663 W if 2 ft closer) based on 6 ohms for one single Ultra speaker to produce 105 dB at you mmp that is 15 ft from the speaker. That requirement would drop to only 70 W (52.7 W if 2 ft closer) if you based on target spl 100 dB, 6 dB room gain, and 2 speakers playing simultaneously. Now you know why I used the word "depend" so often.

Input data required:	Input data	Unit
1) Speaker nominal impedance (Ohms)	6.00	Ohm
2) Sensitivity in dB/W at 1 Meter		dB
3) Sensitivity in dB/2.83 V at 1 Meter	87.00	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	76.80	dB
Amplifier power output based on 2.83 V and the assumed impedance at 1 Meter	1.33	Watt (W)
Power increase in multiples needed to achieve target SPL	661.36
Power increase in dB needed to achieve target SPL	28.20	dB
Calculated amplifier output power required:
For the target SPL at seating distance	882.79	Watt (W)
For the target SPL at seating distance, with the desired headroom included		Watt (W)

You should be able to get the same results if you use that homestead myhometheater calculator, except as you know it is based on 8 ohm impedance, so you have to adjust the result one way or another, in order to match mine.

Man, that 2' makes such a huge difference! I'm assuming the 3 dB higher sensitivity of my Sierras basically halves the requirement for the Ultras? I knew it would, and I know the homestead would get me close. Yours has more detail tho, and I was curious. You know how it is, it's just fun!

I've been putting off scooching closer to my front stage but now I think I'm doing it sooner rather than later. Hope it doesn't screw up my beautiful bass response.

 

[PENG]

Man, that 2' makes such a huge difference! I'm assuming the 3 dB higher sensitivity of my Sierras basically halves the requirement for the Ultras? I knew it would, and I know the homestead would get me close. Yours has more detail tho, and I was curious. You know how it is, it's just fun!

I've been putting off scooching closer to my front stage but now I think I'm doing it sooner rather than later. Hope it doesn't screw up my beautiful bass response.

12 ft would be nice. Even for 15 ft, keep in mind that very few people can tolerate reference level with just one speaker playing. I am running 7.1.4 so that's 11 speakers and 5 subwoofers and I still cannot tolerate any more than 80 dB average 100 dB occasional maximum dynamic peaks. I can't imagine how loud it would be with one speaker producing 85 dB average, as that would bring the spl up to potentially and frequently >>90 dB average when 2 or more speakers are playing simultaneously. So to me, 80 dB one speaker, or 84 to 85 dB with 2.1 playing, is already too loud. Under that condition, even your SR6012 should be able to hold its own without the power amp and without moving your seat. For action movies, a good part of the spl will be from the powered subwoofers anyway.

 

[PENG]

Thank you so much for all this information. Please let me know if I am understanding you correctly:

I should be able to get approx. 80db average , 100db peak (content dependant) with my Marantz receiver alone and it would be set between -10 to -8 volume?

I should be able to get approx. 85db average, 105db peak with the Monolith amp and the volume would be set to -5?

Some other comments:

I rarely ever listen to the volume higher than -10, so does this mean that perhaps my Marantz receiver is more than adequate for my current listening levels.

I noted you mentioned a few times that the numbers you mentioned are without a sub. I actually have two PSA v1500 subs, and the speakers are crossed over at 80hz.

Without knowing the actual measured room gain you are getting, and it is so much contents dependent, as well as the speaker's impedance curve dependent, those values should get you in the ball park but could be off by +/- a few dB.

I would say your Marantz can hold its own, but AVRs are not really designed for 4 ohm speakers so you should put one of those Infinity fan on top. Also, since you listen on the loud side, the SR5005 may be pushed to output higher than 1.2 V frequently. If you are one of those who can be bothered by THD+N as low as 0.1%, you really should upgrade the AVR. Again, the best deal now is the AVR-X3600H. I have been recommended it because of its specs, features and bench test measurements that beat the Marantz AV7705 in significant ways, and also beat the flagship AV8805 though only by very small margin. The X3700H should be even better because it has the full preamp mode. The X3600H is basically a SR6014 without the HDAM (likely the reason why it measures better than Marantz).

 

[Pogre]

12 ft would be nice. Even for 15 ft, keep in mind that very few people can tolerate reference level with just one speaker playing. I am running 7.1.4 so that's 11 speakers and 5 subwoofers and I still cannot tolerate any more than 80 dB average 100 dB occasional maximum dynamic peaks. I can't imagine how loud it would be with one speaker producing 85 dB average, as that would bring the spl up to potentially and frequently >>90 dB average when 2 or more speakers are playing simultaneously. So to me, 80 dB one speaker, or 84 to 85 dB with 2.1 playing, is already too loud. Under that condition, even your SR6012 should be able to hold its own without the power amp and without moving your seat. For action movies, a good part of the spl will be from the powered subwoofers anyway.

Part of my motivation too, is the couple of times I've taken my new speakers up to reference, all 3 drivers looked like they were gonna jump out of their baskets from the excursion and it made me a little nervous. I could see them bouncing from my MLP! I have more power on tap than they can handle so my goal is to take advantage of their sensitivity and not drive them so hard.

Altho earlier today I had them cranked up and they were handling it like champs. I've started thinking maybe I'm fussing over nothing and they're operating within their limits. I'm used to bigger drivers. Bigger drivers don't need to move as much and maybe just I'm not used to seeing it. The reverse of going from a sealed 12" sub to a ported 15". When I did that I didn't think the 15s were moving the way they were supposed to because I was used to seeing the 12s struggle to fill the room.

 

[PENG]

Part of my motivation too, is the couple of times I've taken my new speakers up to reference, all 3 drivers looked like they were gonna jump out of their baskets from the excursion and it made me a little nervous. I could see them bouncing from my MLP! I have more power on tap than they can handle so my goal is to take advantage of their sensitivity and not drive them so hard.

Altho earlier today I had them cranked up and they were handling it like champs. I've started thinking maybe I'm fussing over nothing and they're operating within their limits. I'm used to bigger drivers. Bigger drivers don't need to move as much and maybe just I'm not used to seeing it. The reverse of going from a sealed 12" sub to a ported 15". When I did that I didn't think the 15s were moving the way they were supposed to because I was used to seeing the 12s struggle to fill the room.

Excellent point about the speaker's limit!! You should ask Ed for the limit in terms of max spl at 1 meter, who will likely be open enough to tell you via email. I suspect it will be about 113 to 115 dB.

Let's assume it can do 115 dB at 1 meter, that means it can do 102 dB at 4 meters without room gain. 4 meter is a little over 13 ft. So if you sit 15 ft, you will get 101.8 dB. With 3 dB room gain, you can just make it to reference level. But then to hit reference level from 15 ft with 3 dB room gain, you need 883 W, can the Ultra handle 883 W, I doubt it, except for may be a few seconds. Specs say 300 W. So I guess you are right, the speakers are often the limit too, not just amp power.

 

[Pogre]

Excellent point about the speaker's limit!! You should ask Ed for the limit in terms of max spl at 1 meter, who will likely be open enough to tell you via email. I suspect it will be about 113 to 115 dB.

Let's assume it can do 115 dB at 1 meter, that means it can do 102 dB at 4 meters without room gain. 4 meter is a little over 13 ft. So if you sit 15 ft, you will get 101.8 dB. With 3 dB room gain, you can just make it to reference level. But then to hit reference level from 15 ft with 3 dB room gain, you need 883 W, can the Ultra handle 883 W, I doubt it, except for may be a few seconds. Specs say 300 W. So I guess you are right, the speakers are often the limit too, not just amp power.

Peng, I think you missed that I bought a pair of Ascend Acoustics Sierra ribbon towers and received them last week. They're the ones I'm concerned about over driving. They're 4 ohm speakers and well, here are the specs.

*Edit: They're rated for more than I realized! For some reason I was thinking it was 150w max continuous power.

SIERRA TOWER PAIR

Introducing our Flagship Loudspeaker "The midrange on the Towers...is a main event. Inner detail is fantastic even on large-ensemble recordings, and they are free from distortion and retain a hefty amount of dynamic headroom when played at spirited levels." -Enjoy the Music.com Combining...

www.ascendacoustics.com

That page is for the dome tweeter version of the Sierra. Here's a link to a pdf for measurements and specs for the ribbons.

http://www.ascendacoustics.com/pages/products/speakers/SRT/Ascend%20Sierra%20Ribbon%20Tower.pdf

 

[operamatt]

just ordered.

 

[Verdinut]

just ordered.

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!

 

[PENG]

Peng, I think you missed that I bought a pair of Ascend Acoustics Sierra ribbon towers and received them last week. They're the ones I'm concerned about over driving. They're 4 ohm speakers and well, here are the specs.

View attachment 37053
View attachment 37055

*Edit: They're rated for more than I realized! For some reason I was thinking it was 150w max continuous power.

SIERRA TOWER PAIR

Introducing our Flagship Loudspeaker "The midrange on the Towers...is a main event. Inner detail is fantastic even on large-ensemble recordings, and they are free from distortion and retain a hefty amount of dynamic headroom when played at spirited levels." -Enjoy the Music.com Combining...

www.ascendacoustics.com

That page is for the dome tweeter version of the Sierra. Here's a link to a pdf for measurements and specs for the ribbons.

http://www.ascendacoustics.com/pages/products/speakers/SRT/Ascend%20Sierra%20Ribbon%20Tower.pdf

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)

 

[PENG]

To be clear, as buckchester mentioned before, it is also my opinion that in practical term such potential concerns about "over driving" something... would likely be moot in most cases. For two channel music, one wouldn't likely be listening anywhere near the so called reference level without subwoofers as they most likely realize the speakers wouldn't be up to it unless they sit close.

For HT, again as buckchester alluded to, most of what contributed to the 85 dB average 105 dB peaks would came from the powered subwoofer(s).