Monoblocks for theater?

[Talley]

Just curious if anyone is running individual monoblocks for each channel on their theater?

My long term plan is to move to monoblocks for this setup. Only issue would be if I get my room turned the right way and move to the atmos setup of 7.2.4... thats 11 monoblocks.

 

[Tony V.]

Thats a lot of overkill, The idea with monoblocks is to give better channel separation but with todays receivers/amps this is far less a concern not to mention that with home theater you would be hard pressed to hear any difference given how much sound is sent to various channels at the same time.

 

[Matthew J Poes]

Just curious if anyone is running individual monoblocks for each channel on their theater?

My long term plan is to move to monoblocks for this setup. Only issue would be if I get my room turned the right way and move to the atmos setup of 7.2.4... thats 11 monoblocks.

In my mind the advantage of monoblocks comes from two things. The isolation of the amplifiers power supplies and modules maximizes channel separation. That's a good thing. The other is that the separate power supplies provides for more power reserves.

Taking those two advantages, I think that implies the real advantage is going to come largely from the mains being on monoblocks over the rest of the system. I think 3 monoblocks and your Krell amplifier is a good compromise that won't have a detrimental effect on sound. I imagine this would be a small advantage in the first place.

I don't run true monoblocks, but I do use a number of separate amps. My main amps and my center amp are separate from each other. My main amp has two completely separate channels with dedicated power supplies receiving separate feeds from the single toroidal transformer and initial large power supply caps. I believe your Krell takes that a step further with separate taps on the transformer for each channel and separate main caps. So where mine has local caps and a larger bank, I believe the Krell is completely separate. That means the only thing shared in your current amp is the toroidal core and the power cord, they are still fairly isolated from each other. I think both my setup and your current setup thus has as much channel separation as you are likely to see.

Out of curiosity, is this just something you want to try, or is there an issue with the sound you want to improve? Something you don't like that you are hoping this will address?

 

[Todd Anderson]

I’d have to agree that you’ll likely not hear the benefits. I like Matt’s suggestion of only going separates for the front 3 channels.

 

[Talley]

Mostly just headroom, power reserve... isolation... etc. I have only one complaint and thats I don't have matching full towers at every channel with matching subs for every channel. Why do I need that? I don't. Some people drive civics... others drive corvettes... some thing corvettes are lame so they drive twin turbo 1,000hp corvettes.

I'm the twin turbo corvette driver.

 

[Talley]

I’d have to agree that you’ll likely not hear the benefits. I like Matt’s suggestion of only going separates for the front 3 channels.

Then why does imax do monoblocks for every speaker?

 

[Matthew J Poes]

Mostly just headroom, power reserve... isolation... etc. I have only one complaint and thats I don't have matching full towers at every channel with matching subs for every channel. Why do I need that? I don't. Some people drive civics... others drive corvettes... some thing corvettes are lame so they drive twin turbo 1,000hp corvettes.

I'm the twin turbo corvette driver.

It might be that the best solution for you is to upgrade your speakers then. Your speakers are very good for what they are, but if you want a twin turbo corvette, well, maybe more efficient and higher power handling speakers will give you what you are looking for.

The SVS speakers are always going to be limited in maximum output by virtue of their design. Their own efficiency and power handling is a limitation. This is partly why I have the speakers I have. My speakers have a 95-96db efficiency rating and an RMS power handling of likely 1000 watts (I say likely because Earl Geddes didn't test them, but the crossover design and the way I built is allows for most of the power to be directed to the woofer, which handles 1000 watts RMS). That means I can get more than 120db's out of each speaker. I have 3 matched speakers up front.

Remember that to increase output by 3db's requires doubling the power. Your current speakers are rated for 87db's and the recommended power is up to 250 watts. I imagine they could handle more for peaks, but lets stick with that for now. If you had 125 watts RMS now then doubling that gains you just 3db's per speaker. A pair of these SVS speakers listened to at 12 feet with 250 watts peaks out at 102db's or so. Move to a speaker with 95 db efficiency and you are now looking at 110db's max rms output with the exact same amplifier. You would need 1500 watts per channel for the original SVS speaker to achieve that same output. Hence why at some point its better to upgrade the speakers than the amps. Your wall can't deliver 3000 watts to the mains and feed all the other channels and subs.

Again, this is not a knock on the SVS speakers. They are a tremendous value and provide great sound, great measured performance, and are something I would recommend to people. But if you want twin turbo corvette performance with monstrous output, I think a different tool is in order. High output and good sound is possible but the cost is higher than what you have now, unfortunately. Let me know if that idea interests you at all.

 

[Matthew J Poes]

Then why does imax do monoblocks for every speaker?

They don't do it for sound reasons. They have custom Bryston amplifiers with analogue low level crossovers. Each speaker has a dedicated amplifier because the amplifier is dedicated to the speaker. The filter is unique. They also need to hit very high SPL levels and it is not feasible to build Class AB amplifiers that can produce that amount of power, to biamp each speaker, given the number of channels they have. What we do in a home is very different. You would have to remove your crossovers, get 8 channels of amplification for just your left and right speaker, and replicate the crossovers in an active form to do what imax is doing. It's not really feasible for the average person (and the advantages would still be very small in a home).

 

[Todd Anderson]

Believe me, I get where you’re going. I have quad subs that could easily tackle a room three times bigger than mine... I’m a bass junkie. Headroom and limitless power are definitely desirable.

If you have to space to pull off a matching 7-Channel arrangement, I’d go for it. And depending on the speaker, you might reap benefits from monoblocks.

What kind of mains do you run?

I do wonder though, why not get a couple of Emotiva’s multichannel amplifiers... perhaps if you’re gear is good enough, you might find a hole in sound, but I’m not entirely sure my ears could hear it.

 

[Matthew J Poes]

Sorry I just realized you have the Ultra and not the prime. They are 88db efficient and 300 watts. The difference in peak SPL isn't great. The effect is scalable, it adds just one db to what I said earlier. You still need 1200 watts for two speakers at 12 feet to hit 110db's.

 

[AudioThesis]

Mostly just headroom, power reserve... isolation... etc. I have only one complaint and thats I don't have matching full towers at every channel with matching subs for every channel. Why do I need that? I don't. Some people drive civics... others drive corvettes... some thing corvettes are lame so they drive twin turbo 1,000hp corvettes.

I'm the twin turbo corvette driver.

The difference here is that the twin turbo corvette driver sees real gains from those upgrades. In this instance, upgrading to monoblocks is just an expense in futility. Getting monoblocks would be akin to separating a single 1000 HP engine into two 500 HP engines.

 

[Talley]

Both of you guys are right. I'll be spending the rest of my life upgrading so this isn't something I can achieve overnight. Eventually I'll have to move and build a home around a theater room itself. No joke. I'm still in infancy stage. Heck I have much more to do with the current room I'm in as far as acoustics.

Without a doubt I'll be able to get only so far in my current room. Speakers are without a doubt your #1 most important item and of course I have limitations with my ultras. Come with individual monoblocks will then need better speakers.... but I just don't need loud speakers. I need good sounding speakers. I've been eyeing the golden ear Triton ones for the main three up front then triton 3s for the surrounds and Aon 3's for the ceilings. Again space is limited.... would be hard to pull off in my room so I have to compromise.

Just seeing if anyone here has or known anyone who has done monoblocks.

 

[Talley]

Sorry I just realized you have the Ultra and not the prime. They are 88db efficient and 300 watts. The difference in peak SPL isn't great. The effect is scalable, it adds just one db to what I said earlier. You still need 1200 watts for two speakers at 12 feet to hit 110db's.

Yes, read my message above. Not about the max spl... heck I'd deaf.

 

[AudioThesis]

I have used a handful of monoblocks and I'd never dream of it for a home theater application - maybe a multi channel SACD setup, but never home theater. There are much more effective ways to use that money.

 

[Matthew J Poes]

Both of you guys are right. I'll be spending the rest of my life upgrading so this isn't something I can achieve overnight. Eventually I'll have to move and build a home around a theater room itself. No joke. I'm still in infancy stage. Heck I have much more to do with the current room I'm in as far as acoustics.

Without a doubt I'll be able to get only so far in my current room. Speakers are without a doubt your #1 most important item and of course I have limitations with my ultras. Come with individual monoblocks will then need better speakers.... but I just don't need loud speakers. I need good sounding speakers. I've been eyeing the golden ear Triton ones for the main three up front then triton 3s for the surrounds and Aon 3's for the ceilings. Again space is limited.... would be hard to pull off in my room so I have to compromise.

Just seeing if anyone here has or known anyone who has done monoblocks.

The tritons would be a lateral move in my opinion. http://jtrspeakers.com/home-audio.html this is a better example of what I mean by good sound and high output. Jeff uses a good waveguide design, very high quality drivers (some of which are custom) and good crossover design. The speakers have all the qualities of an audiophile speaker with a significant increase in output.

Unfortunately my own speakers are out of production, Dr. Geddes fully retired finally, but he designed them based on the optimal oblate spheroid waveguide which he had shown to provide the best sound and pattern control. Combined with very good and very expensive drivers I think of them as among the best speakers around.

There are also some really good DIY options these days. Some very talented and professional designers have helped bring some really good kits to market that again use very good drivers.

 

[Talley]

Funny you mention JTR as my ultimate LFE channel setup would be dual cap4000's. Not really that bad of a cost for what your getting too.

 

[Matthew J Poes]

Funny you mention JTR as my ultimate LFE channel setup would be dual cap4000's. Not really that bad of a cost for what your getting too.

Yes his subwoofers are a great value for what they are. Most of us with AV NIRVANA happen to know Jeff one way or another and know him to be a standup guy. I really like his products.

I heard a pair of his speakers in a shootout of sorts a few years back and it was by far the best sounding speaker of the bunch. There were also Triton Ones and Klipsch Reference speakers in the grouping. I don't believe anyone preferred either of those to the JTR's. They were all played in a level matched format back to back, so volume/dynamics were not the issue. The JTR just sounded better. I can also attest to it not being a bias due to cost, most of the people in attendance didn't want the JTR to sound better because they were more expensive than most of the other speakers. Unfortunately for all of us, the performance gap was undeniable.

I've heard lots of great speakers of different design ilk. Skip (Audiothesis) carries a line of audiophile speakers of fairly conventional dynamic driver design approach. The bookshelf I heard sounded magnificent, with (to date) among the very best sound staging I've ever heard. I've heard top of the line McIntosh speakers (giant Line Arrays), Klipsch, Polk, SVS, Gedlees, JTR's, Magnepan, Revel Ultima Salon's, Sonus Fabre Amati Homage, Focal Utopia's (I owned these), etc. I've heard many of these for fairly extended periods of time in good rooms with excellent equipment and familiar music. What I can say is that they all sounded different and each had their merits (at least among the better speakers). One reality came out of this though, if you want realistic dynamic range and headroom for things like cinema reference levels, high efficiency speakers are a must. That meant that when I looked for my ideal speaker, I wanted high efficiency, but not at the expense of good sound. There are a number of high efficiency speakers on the market that can achieve the high dynamic range, but I do not think they offer audiophile sound. I find them flawed and compromised. However, there are a handful that are not just good, I think they are the best sounding speakers on the market (weighing all these different criteria of accurate tonality, smooth response, high output, low distortion, good pattern control, etc.). The best speaker I've ever heard remains the Gedlee Summa (no longer in production as noted). I like my own Abbeys (a size smaller) quite a bit (let's call them the second best sounding speaker I've ever heard). In a similar ilk I have now also heard the JTR's and JBL M2's and find them to be similarly great sounding. We can call them 3rd best sounding, but admittedly we are talking about very small differences and the JTR and M2 have more bass and other advantages I like, they really are more like a different great speaker, rather than 3rd best. Next to that, my favorites are the Revel Ultima Salons.

I think speakers are where you should spend the most money, but I also think that speakers, because they make the biggest sound difference, are a very personal thing. You have to have something you love.

 

[Talley]

I would agree 100%. I just didn't know of any good high efficient speakers. I trust your experience as it far exceeds mine. My only solid reference I can lean on is my uncle who is a die hard 2ch guy.... which things are done slightly different in the multi channel realm.

I'd really need to listen to those JTR's because it's not out of my budget. I was thinking when that time comes around 10k for a 5 channel setup.... add in the ceilings maybe a few grand more. As far as monoblocks... well I have no issue doing a great 3 channel setup then running the 4 ceilings on a 5 channel amp and the remaining on a 7 channel. That is three amps and could all be managed with placement with ease with the way I prefer the rack to sit. Wouldn't utilize all those channels but individual monoblocks would indeed be a pain but a mild one... Still plausible. I'm not concerned with cross-talk... just headroom. Crazy dynamics and I never disputed better speakers.

First step is to get the SVS system to the best of my ability and that is getting my room setup to the best of it's ability. All gear compliment each other and the room. It's foolish to swap gear out without having each component the best you can for each other.

 

[Matthew J Poes]

I would agree 100%. I just didn't know of any good high efficient speakers. I trust your experience as it far exceeds mine. My only solid reference I can lean on is my uncle who is a die hard 2ch guy.... which things are done slightly different in the multi channel realm.

I'd really need to listen to those JTR's because it's not out of my budget. I was thinking when that time comes around 10k for a 5 channel setup.... add in the ceilings maybe a few grand more. As far as monoblocks... well I have no issue doing a great 3 channel setup then running the 4 ceilings on a 5 channel amp and the remaining on a 7 channel. That is three amps and could all be managed with placement with ease with the way I prefer the rack to sit. Wouldn't utilize all those channels but individual monoblocks would indeed be a pain but a mild one... Still plausible. I'm not concerned with cross-talk... just headroom. Crazy dynamics and I never disputed better speakers.

First step is to get the SVS system to the best of my ability and that is getting my room setup to the best of it's ability. All gear compliment each other and the room. It's foolish to swap gear out without having each component the best you can for each other.

You will want to listen to the speakers before buying them if possible. At least look for a 100% money back guarantee of sorts or an in home trial program.

There is no such thing as a perfect speaker. Every driver type and design has its benefits and pitfalls. Just some quick facts

1. Ribbon and Planar drivers (often touted as having lower distortion) often have greater efficiency and a more extended frequency response (well past 20khz) but high distortion, especially in their lower range. This distortion can be high enough to be a problem. They also have generally poor off-axis response in many designs and so are best used as super tweeters or in three way designs.
2. Dome tweeters have a very smooth response with very low distortion, but often have poor off-axis performance
3. Standard dynamic midbass drivers often have a very smooth response and very low distortion, but low power handling and low efficiency limiting their dynamics
4. High efficiency pro audio drivers have high power handling and high dynamic range but the response is often not as smooth and the bass extension is poor given their size
5. Poorly designed waveguides or horns can increase distortion, add response anomalies, and cause bad sound
6. Good waveguides don't add distortion or response anomalies, and offer the most practical way to provide off-axis pattern control
7. Speakers with controlled directivity ensure that the wall reflections have a similar response to the direct signal which is found to be optimal, but toe angle becomes critical to good sound
8. Direct radiators can be made to have a very smooth 180 degree dispersion (See Vivid Audio for an unusually good example), and while this provides a very wide sweet spot, it's also known to be detrimental to imaging if not setup well and the room isn't setup to handle it. Vivid Audio's chief speaker designer has actually talked about this himself, so while he considers this the ideal speaker design, he recognizes the problem's it can create.

Because of the above issues, it's hard to make one speaker that does everything well. Two properties have been shown to be the most important for the average listener. Smooth/flat frequency response and a smooth decaying polar response. I consider these two properties to be unequivocally important. If we use high efficiency drivers and cheap horns, we get controlled off axis response, so a smooth decaying axial response, but...it won't be a smooth flat response without aggressive EQ. That isn't a good thing. If we use more standard audiophile drivers like those from SEAS, Scan Speak, Morel, etc. we get a really smooth response, but without a waveguide, we won't have a smooth axial response. Neither is good. If the pattern of the tweeter and midbass isn't accounted for in the crossover design we get a discontinuity off axis. It's sad and amazing how many commercial speakers fall into this category.

 

[Talley]

Good info. Thanks for taking the time to write that.

I've spent hours listening to these Apogee Duetta Signatures that have been completely overhauled. My uncle uses the Audio Research Ref-600 monoblocks to power them. These speakers are without a doubt the best I have ever listened to...

...but I think it's more about the entire system perhaps.

 

[AudiocRaver]

My take is similar to Matt's. Not true monoblocks, but separate amps for L, R, and C (if I had one, I'm running phantom center for now), rears not as critical. It matters to me because my room handles two-channel as well as theater, and the difference with two-channel was noticeable when I made the change.

Tony, you certainly know AVRs 1000x better than I do, but from what I have seen, very few spec channel separation (crosstalk) above 1 kHz. Stellar channel separation at 10 kHz is easy in a preamp with little current flow, but in an AVR or multi-channel power amp with big current flows through common grounds, soundstage and imaging can be affected. Agree that it matters much less for theater than for two-channel.

 

[Matthew J Poes]

Good info. Thanks for taking the time to write that.

I've spent hours listening to these Apogee Duetta Signatures that have been completely overhauled. My uncle uses the Audio Research Ref-600 monoblocks to power them. These speakers are without a doubt the best I have ever listened to...

...but I think it's more about the entire system perhaps.
View attachment 5715

Very cool! Is the baskets and bricks a new kind of acoustic treatment to reduce floor bounce?

I've heard those Apogee's before, but only in an audio shop and I was a teenager at the time.

Please don't take my ribbon comment as a damming comment, the other side of the distortion issue is that if of low order, high levels of distortion don't tend to be audible. Also Apogee's were a whole different kind of ribbon setup, they were much larger. I've never seen measurements for Apogee's so I have no idea how they measure or what their distortion is like. My comment was really based on the measurements that exist for smaller ribbons used in more conventional speakers.

I have seen measurements of Magnepan's (Planar and Ribbon) and while I always enjoyed them, they've always sounded colored to me. Add that they are exceedingly inefficient, very difficult to drive, and you don't have a speaker I can live with. Still, I know many audiophiles who swear by them.

I love the Audio Research amplifiers you have there, great stuff. I've never been lucky enough to own any of that caliber, but I did own the lower end D76s which I rebuilt while in high school/college. They were great amps and I had a lot of fun rebuilding them.

I do think that monoblock tube amps are a good idea. Channel separation on tube gear was not historically great due to the common power supply design. Newer gear is better, but I also think that is due to better power supply designs as well as the use of internally dual mono designs.

 

[Matthew J Poes]

My take is similar to Matt's. Not true monoblocks, but separate amps for L, R, and C (if I had one, I'm running phantom center for now), rears not as critical. It matters to me because my room handles two-channel as well as theater, and the difference with two-channel was noticeable when I made the change.

Tony, you certainly know AVRs 1000x better than I do, but from what I have seen, very few spec channel separation (crosstalk) above 1 kHz. Stellar channel separation at 10 kHz is easy in a preamp with little current flow, but in an AVR or multi-channel power amp with big current flows through common grounds, soundstage and imaging can be affected. Agree that it matters much less for theater than for two-channel.

I could measure that! Do you think anyone besides you and I would even care? It's pretty easy to do. You connect your measurement device (even REW can do it, but a 2 channel device like ARTA is better) to the output of the device in question (for an amplifier you need to add a speaker load). You short the input of one channel (say the left channel) while connecting the input for the other channel (say the right channel) to your signal source. Then you take a measurement of both channels. The difference in Db's between channels is the channel separation response.

Channel separation of the preamplifier section tends to be really good, well over 100db's in modern receivers (I've seen some that measured as high as 130db's near 1khz!). As you know, all devices have less channel seperation as frequency increases unless they are physically separated by a good distance. Amplifiers are a different story, while most receivers use separate "monoblock" amplifier modules on the higher end models, they are VERY close together physically, with the traces even running next to each other or cables bundled together. They pretty much always have a common power supply (Some better designs from NAD, Arcam, and Rotel are exceptions). This is why I generally prefer external amps with a receiver. I think the research into channel separation shows that it doesn't really need to be all that good to be at the limit of audibility, but I think we have already established that sometimes I do things for their technical superiority, audibility be damned!

 

[Talley]

Very cool! Is the baskets and bricks a new kind of acoustic treatment to reduce floor bounce?

I've heard those Apogee's before, but only in an audio shop and I was a teenager at the time.

Please don't take my ribbon comment as a damming comment, the other side of the distortion issue is that if of low order, high levels of distortion don't tend to be audible. Also Apogee's were a whole different kind of ribbon setup, they were much larger. I've never seen measurements for Apogee's so I have no idea how they measure or what their distortion is like. My comment was really based on the measurements that exist for smaller ribbons used in more conventional speakers.

I have seen measurements of Magnepan's (Planar and Ribbon) and while I always enjoyed them, they've always sounded colored to me. Add that they are exceedingly inefficient, very difficult to drive, and you don't have a speaker I can live with. Still, I know many audiophiles who swear by them.

I love the Audio Research amplifiers you have there, great stuff. I've never been lucky enough to own any of that caliber, but I did own the lower end D76s which I rebuilt while in high school/college. They were great amps and I had a lot of fun rebuilding them.

I do think that monoblock tube amps are a good idea. Channel separation on tube gear was not historically great due to the common power supply design. Newer gear is better, but I also think that is due to better power supply designs as well as the use of internally dual mono designs.

Ironically yes the baskets/bricks help break the sound up. I laughed at my uncle and then he cleared the floor and I listened... he then put them down and I was actually amazed how well it did. Nobody ever thinks to treat the floor but if you think about it it's a reflection point too. He has Krell FPB 300 monoblocks, Ref-600's II, Ref-100s, some other kind of tube monoblock pairs.... multitudes of pre-amps, about 27 tuners total...all old stuff. His analog table and such... everything vinyl on the equipment is north of 80k worth.

When I say I've heard the best system of my life... I mean it. Every sort of tweak/trick he has tried... he has demo'd very expensive items. $4k power cables for amps to $6k interconnects... he's tried a ton of gear. In the end he's using 300 dollar balanced interconnects and a mix of various other cables. He has alot... but he said the uber expensive stuff just doesn't do much and most have negative effects. What he has taught me is that no two systems will ever sound the same... he claims that location on earth has an effect due to magnetic fields... atmosphere conditions has an effect on sound... all sorts of stuff. He does swear by morrow audio cables and mapleshades maple isolation blocks. If you notice he has them under everything w/ brass. All his power delivery is through an isolation transformer... all 120v wiring is #8awg. He has some 20 circuits total into his room. He is friends with some of the smartest people in the recording business that deal with equipment.

My uncle is a valuable resource. I've heard his system and until I hear better it's the king for what I've heard. He has since added dual REL subs and some super tweeters. I'll be traveling back to visit him this summer in June and will get some updated photos.

The apogees and his room in general is very flat free of any nulls/modes and his apogee's were -3db at 30hz. He said they were definately good for music but the subs added a solid extension and he said the overall presence of space improved a ton... he said the subs added ambiance that was lacking before. How it can I'm not sure but the guy has been a hifi nut for the past 45 years. He is 63 now. Literally added onto his house for a dedicated room.

 

[AudioThesis]

Your uncle has experience. I like stories like that, especially when real world experience like he showed you is involved. Us 2 channel enthusiasts are not placebo-sucking guys. We work with what works and sometimes what works is unexpected or against our own beliefs, much less those of other audiophiles.