Monolith 7x200 amp vs ... competition? (Looking for experienced amp advice)

[Landmonster]

....

I seem to remember you get as much power supply in the 5 as the 7 Monoliths but it's been a while....search for the review/thread here on Audioholics, think that's where I saw it. Getting the 7channels if eventually needed tho, it seems a slightly better deal than just the 5.

I think that was a false rumor. From Monoprice's website:

"We needed to adjust our specs; The 7 channel has transformers of 1230VA and 1040VA and the 5 channel has transformers of 1040VA and 800VA."

 

[lovinthehd]

I think that was a false rumor. From Monoprice's website:

"We needed to adjust our specs; The 7 channel has transformers of 1230VA and 1040VA and the 5 channel has transformers of 1040VA and 800VA."

Seems the math still works out slightly better for the 5 channel.....

 

[Landmonster]

Seems the math still works out slightly better for the 5 channel.....

For whatever that is worth:

• The Rotel RMB-1095’s power supply is built around two Rotel made 1.2 kVa toroidal transformers.
• The Monolith 5x has a 1.02 kVa, and 0.8 kVA toroidal transformers. .

• The Rotel has 8x15,000uF = 120,000uF total capacitance.
• The Monolith 5x has 5x 22,000 = 112,000µF total capacitance.

I'm not sure as to how the rest of the amps compare to one another, but the Rotel 1095 was a fairly well-respected 5 channel theater amp for many years.

 

[Verdinut]

Did you verify how much power you need to get the SPL you want to obtain using the Polk 707's based on theit 88dB sensivity, at your listening distance from them? I strongly presume that you would have enough power output with one Monolith amp , and wouldn't need to bi-amplify the front L & R channels. You could just get the Monolith 5 amp and truly enjoy your HT system.
EDIT: The voltage gain for the Monolith amp is 28dB

Peak SPL Calculator

 

[Landmonster]

Did you verify how much power you need to get the SPL you want to obtain using the Polk 707's based on theit 88dB sensivity, at your listening distance from them? I strongly presume that you would have enough power output with one Monolith amp , and wouldn't need to bi-amplify the front L & R channels. You could just get the Monolith 5 amp and truly enjoy your HT system.
EDIT: The voltage gain for the Monolith amp is 28dB

Peak SPL Calculator

I have not done any calculations

 

[PENG]

Its 2.8 ohms at 66hz with a 32 degree angle. It is pretty reactive, but I doubt the ATI amps would have an issue, some AVRs definitely.

I'm pretty much convinced that I'm sticking with QSC cinema series for amps here on out. They don't break a sweat with the Salks, not that difficult to drive, full range with high spl.

I cannot understand why Polk Audio never seem to bother telling potential buys the truth, that those speakers are not nominal 8 ohms, but closer to 4 ohms based on the common understanding of "nominal".

They can sound right with AVR at low to moderated low spl, say 75 dB listening near field, say from 8-10 ft. So yeah most AVR are not going to cut it.

By the way, if their nominal impedance spec seemed wrong, why would people believe their sensitivity spec, their advertised spec claimed: "Sensitivity (1 watt @ 1 meter)88 dB", they could well be closer to 88 dB/2.83 V@1m, and the 1 watt thing might have been a printing error??

 

[PENG]

Did you verify how much power you need to get the SPL you want to obtain using the Polk 707's based on theit 88dB sensivity, at your listening distance from them? I strongly presume that you would have enough power output with one Monolith amp , and wouldn't need to bi-amplify the front L & R channels. You could just get the Monolith 5 amp and truly enjoy your HT system.
EDIT: The voltage gain for the Monolith amp is 28dB

Peak SPL Calculator

I would normally agree but I am not sure in this case because:

- the price difference is $300, that's $150 for each 200 W amp, very cost efficient.
- the 707 appears to have the 6.5" mid woofer grouped with the tweeter and midrange.

So I think even passive bi-amp can help both groups of drivers to get cleaning signal under certain conditions and the improvement in the mid and especially high range could be audible.

 

[PENG]

Generally the passive bi-amping thing is "solved" by simply using a more powerful amp in the first place. I certainly wouldn't buy the wire for passive bi-amping let alone amp channels for it. Active bi-amping with a diy speaker project might be well worthwhile, tho.

I seem to remember you get as much power supply in the 5 as the 7 Monoliths but it's been a while....search for the review/thread here on Audioholics, think that's where I saw it. Getting the 7channels if eventually needed tho, it seems a slightly better deal than just the 5.

Have no idea about the Rotel other than it seems similarly spec'd but here's the AH review if you haven't seen it....https://www.audioholics.com/amplifier-reviews/rotel-rmb-1095

You remember right, I was the one who pointed out the better transformer VA to Watt ratio for the 5 channel version. It turned out to be "too good to be true" as Monolith clarified that it was a typo of some kind in the VA spec that has since been "corrected", though I lost faith in their transformer VA specs. Two transformers specified, with different VA rating and no information provided for how they are connected to the amps.

It is good that they published them, as very few (if any) disclosed this important spec for class AB amps but only really good if they are accurate.

 

[PENG]

I think that was a false rumor. From Monoprice's website:

"We needed to adjust our specs; The 7 channel has transformers of 1230VA and 1040VA and the 5 channel has transformers of 1040VA and 800VA."

That wasn't a rumor, it was a mistake by Monolith, until they corrected it. If not raised/questioned by some, they might or might not have corrected it. That error was there for a long time.

 

[Landmonster]

That wasn't a rumor, it was a mistake by Monolith, until they corrected it. If not raised/questioned by some, they might or might not have corrected it. That error was there for a long time.

Okay so what is the definitive answer here?

If you were buying the monolith amp for a 5- channel system, with the LSiM 707 Polk speakers as your main towers... Would you choose the monolith 5 or 7 and why?

Bonus question, how does a used Rotel 1095 stack up against these?

 

[Pogre]

I bought the 7 channel version with future proofing in mind, but I think the 5 will work great for your application. Don't let bi amping be the determining factor for the extra channels if you otherwise don't need them.

 

[CajunLB]

I’d get the 5 channel Monoprice, not worry about bi-amping. And enjoy my nice system. But that’s only my opinion.

 

[Landmonster]

I bought the 7 channel version with future proofing in mind, but I think the 5 will work great for your application. Don't let bi amping be the determining factor for the extra channels if you otherwise don't need them.

My living room can truly only hold five of these speakers. Without looking very tacky...

So if I got the 7 channel version, the only possible reason would be to buy amp the 707 towers. Otherwise, the extra two channels will be sitting unused for several years until I move to a different home which may or may not have a real media room.

But that's also why I was asking is there any kind of power supply or other unknown specification difference, which would cause an acoustic advantage for either the five channel or the 7 channel amplifier. Better parts, cooling, power supplies, etc?

 

[Pogre]

My living room can truly only hold five of these speakers. Without looking very tacky...

So if I got the 7 channel version, the only possible reason would be to buy amp the 707 towers. Otherwise, the extra two channels will be sitting unused for several years until I move to a different home which may or may not have a real media room.

But that's also why I was asking is there any kind of power supply or other unknown specification difference, which would cause an acoustic advantage for either the five channel or the 7 channel amplifier. Better parts, cooling, power supplies, etc?

I'm gonna go out on a limb here and say there would be absolutely no audible advantage going from 5 to 7 channels or vice versa. Just go with what you need for the job. I've had 2 channels sitting unused since I got the damned thing, lol.

However, I have plenty of room, don't find speakers to be tacky (I actually like the way my speakers look, they're gorgeous) and have plenty of flexibility if I wanna add channels or end up with some difficult to drive speakers. I've even been considering putting a nice stereo pair of indoor/outdoor speakers on the patio.

 

[PENG]

I

My living room can truly only hold five of these speakers. Without looking very tacky...

So if I got the 7 channel version, the only possible reason would be to buy amp the 707 towers. Otherwise, the extra two channels will be sitting unused for several years until I move to a different home which may or may not have a real media room.

But that's also why I was asking is there any kind of power supply or other unknown specification difference, which would cause an acoustic advantage for either the five channel or the 7 channel amplifier. Better parts, cooling, power supplies, etc?

Thought your reason was to passive biamp the L/R.

 

[Pogre]

I think he's way over-thinking it. Any differences are going to be more cosmetic than audible. Any well built amp is going to sound good as long as you're not pushing it past its limits. Get the Monolith 5 and call it a day.

 

[CajunLB]

I think he's way over-thinking it. Any differences are going to be more cosmetic than audible. Any well built amp is going to sound good as long as you're not pushing it past its limits. Get the Monolith 5 and call it a day.

Totally agree. I think you are way over thinking and just need the 5 channel also. The 7 channel is only more money and also starting to become very heavy and awkward because of the weight.

 

[Landmonster]

Just an update. To all you guys who input ideas

I hope I didn't do something stupid. I might have... or might have made a good deal. Let me know what you think.

I ended up purchasing a very clean (supposedly) used Emotiva XPA-7 gen3 from Audiogon for about $1500. It is being shipped to my house as we speak. (The new price on these is around ~$2100 + tax and shipping)

It provides 300watts into 2 channels, or 250x5, or 200x7 with a shared switch-mode power supply. The power delivered varies based on the number of channels you are driving at the time, so that seems like an interesting design, which would be good for me.

After further research on the Emotivas, it seems like if you are going to purchase a Gen3 XPA series, then it makes the most sense to purchase the XPA-7, because all the amplifier cards are "modules", and exactly the same as each-other. So, given that the chassis size are all the same, you'd rather have 7 of the modules in the same size chassis instead fewer of them. The XPA-7 gives you the flexibility to run 2, 3, 5, or 7 channels with no loss of power as compared to buying a XPA-2, or XPA-3, etc.

This seems like this should have plenty of power for the Polk LSiM series. I am not really concerned about lack of power with this design. However, I just wonder if the Emotiva sound quality will be up to par with more fancy brands. I also wonder if this design style will hold up to the test of time over a 5, 10, or 15 year period.


It is good that this thing conserves power when it's not being used, and outputs less heat, so that should result in some cost savings over time.

I could not locate exact a long list of detailed specifications on the amp. I'm not an electrical engineer, so I wouldn't even be quite sure what I am looking at, either. However, most of the other amps don't publish a full list of specs besides the Monoprice.


It seems that very nice 200w+ 5-channel amps are hard to find around $1,500, especially if you include shipping and taxes.


If this particular XPA-7 has poor sound quality, or it has reliability problems, or if there is some other noteworthy problem, I will have to dispute the transaction, or sell the amp and find something else. Sadly, I don't have other amps on hand to to an A/B comparison with.

 

[Pogre]

Personally I would have gone with a brand new Monolith with a full warranty over used for that kind of money. I think you spent more and you're not really gaining anything. One is going to sound just as good as the other and if your speakers are lower impedance you're not even gaining a lot in power (Monolith is rated at 300 wpc at 4 ohms and exceeded that in gene's review)...

That said, the XPA-7 is a great amp and as long as it doesn't crap out on you I'm sure you'll be happy with it.

 

[everettT]

Just an update. To all you guys who input ideas

I hope I didn't do something stupid. I might have... or might have made a good deal. Let me know what you think.

I ended up purchasing a very clean (supposedly) used Emotiva XPA-7 gen3 from Audiogon for about $1500. It is being shipped to my house as we speak. (The new price on these is around ~$2100 + tax and shipping)

It provides 300watts into 2 channels, or 250x5, or 200x7 with a shared switch-mode power supply. The power delivered varies based on the number of channels you are driving at the time, so that seems like an interesting design, which would be good for me.

After further research on the Emotivas, it seems like if you are going to purchase a Gen3 XPA series, then it makes the most sense to purchase the XPA-7, because all the amplifier cards are "modules", and exactly the same as each-other. So, given that the chassis size are all the same, you'd rather have 7 of the modules in the same size chassis instead fewer of them. The XPA-7 gives you the flexibility to run 2, 3, 5, or 7 channels with no loss of power as compared to buying a XPA-2, or XPA-3, etc.

This seems like this should have plenty of power for the Polk LSiM series. I am not really concerned about lack of power with this design. However, I just wonder if the Emotiva sound quality will be up to par with more fancy brands. I also wonder if this design style will hold up to the test of time over a 5, 10, or 15 year period.


It is good that this thing conserves power when it's not being used, and outputs less heat, so that should result in some cost savings over time.

I could not locate exact a long list of detailed specifications on the amp. I'm not an electrical engineer, so I wouldn't even be quite sure what I am looking at, either. However, most of the other amps don't publish a full list of specs besides the Monoprice.


It seems that very nice 200w+ 5-channel amps are hard to find around $1,500, especially if you include shipping and taxes.


If this particular XPA-7 has poor sound quality, or it has reliability problems, or if there is some other noteworthy problem, I will have to dispute the transaction, or sell the amp and find something else. Sadly, I don't have other amps on hand to to an A/B comparison with.

Pretty sure some linked a reason not to go with them, and it seemed like a very compelling one.