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WANTED: 5,6,7 channel amp recommendations
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Old 26th January 2017, 07:24 PM   #1
CharlieLaub is offline CharlieLaub  United States
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Default WANTED: 5,6,7 channel amp recommendations

I am stuck. In the recent past I bought various amplifier parts (amp modules, transformers, caps, bridge rectifiers, etc.) only to discover that I have very little enthusiasm or motivation for building amplifiers! Oops. The problem seems to be that I can't decide how to proceed with the build. I have been trying to figure out how to do so for the last 3 months without being able to arrive at a solution that I am satisfied with. Part of the problem seems to be that I need construct at least 5 channels of amplification and putting this into a respectable physical form in a chassis (or two or three) with all the necessary accessories that a large power amp requires is seemingly not within a skill set that is familiar to me. I don't have the tools to machine metal except very basic drill press work and even that seems daunting (drill and tapping holes for example). I find myself scratching my head each day trying to come up with a different approach, a physical arrangement that makes sense, etc. and each day I go do bed without having made an inch of progress. This is holding up a couple of loudspeaker projects that I have started, which both require 5 channels of 100W or more into 8R, and at least same or greater (e.g. 150W) power into 4R. I am so frustrated that at this point that I am considering thinking of throwing in the DIY towel on this one and just buying a pair of multichannel amplifiers so that I can move on with things. I might return to amp building in the future, especially if the project goals are a bit easier to handle.

I started looking at multichannel amps (at least 5 channels are necessary) and came up with a couple of possibilities:
  • Emotiva A-500 ($499)
  • Outlaw 5000 ($599)
  • Outlaw 7140 ($1099)
I need an identical pair of these amps.

I got a recommendation for the Emotiva brand and at first the 5-channel A-500 looked interesting. But I noticed that the specs state full power only for two channels running concurrently and I found a picture inside that shows what looks to be a rather anemic power supply and undersized heat sink with two very cheap looking internal FANS blowing air sideways against the HS. This does not seem to be the kind of construction and level of quality that I want to invest in.

Next, I discovered the 5-channel Outlaw 5000. At $599 it's only $100 more than the A-500 yet you seem to be getting a lot more. Each channel is rated for 120W@8R, 180W@4R with all channels driven and has its own heatsink. The transformer is rated for 0.9kVA, which is about equal to total amp rated output power into 4R. On the downside the cap section has four 6800uF caps per channel but they are connected in series parallel (wha?) so that the total capacitance is only 6800uF per channel. It's barely OK my opinion, and this seems like a bit of a weak point. The lone review with testing seemed to indicate that the amp does meet and exceed its rated specs, however, so maybe this is not of much concern when new, but as the caps age any loss is capacitance may be problematic. Looking at a pic of the open chassis it seems like there is room for more or larger caps, so I am not sure why Outlaw chose this cap bank configuration. The amp is built in China but evidently at a reputable factory. For $599 it seems like a good deal and it is high on my list at this point.

Stepping up, and a bit of overkill for my application, there is the 7-channel Outlaw 7140. This amp has only very recently become available from Outlaw and is evidently a redesign of the 7125, which has a very good reputation and is another step up from the quality level of the 5000. Inputs now include both balanced (XLR) and unbalanced. Balanced inputs use THAT receiver ICs. The amp has a soft-start circuit and each channel is self contained on its own circuit board. Made in USA, and quality from top to bottom looks excellent. At $1100 each this is a bit more than I was hoping to spend, however, it would be a quality piece that I could rely on for years to come for just about any multiway loudspeaker project that I can dream up. I did already find one person who purportedly experienced a ground loop problem with his 7140 and was selling it. Evidently this was when he connected it to his "plasma TV" and I am sure this way via an unbalanced interconnect. Other than that there is little to go on but the reputation of Outlaw and this amp's predecessor.

So, at this point I am looking for some advice on how to choose, and whether I should consider other multichannel amps. Keep in mind that the price of EACH should not exceed about $1000 and this puts amps like the Emotiva XPA Gen3 5-channel ($1500) out of reach. Although I prefer a class-AB amp, perhaps there is a 5-channel class-D amp I should look at? There are some ncore offerings but they all seem to be much more than I am willing to spend.

Your thoughts and advice are appreciated!
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Old 26th January 2017, 08:12 PM   #2
cbdb is offline cbdb  Canada
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Do you just want the power amps, no multi channel decoding? ( the Dolby, DTS that most movie sound comes as). If you want processing Marantz uses quality power amps, due to economies of scale it may even be cheaper than just a 5 channel power amp of equal quality. And you get preamp (switching (audio and video), playback of USB devices, network, blue tooth, Audacy, etc) for free.
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Old 26th January 2017, 08:33 PM   #3
Michael Chua is offline Michael Chua  United States
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If you want to spend as little as possible, I have a used Rane MA6s that I'm willing to part.
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Old 26th January 2017, 08:49 PM   #4
CharlieLaub is offline CharlieLaub  United States
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I'm looking for two separate power amps (no additional decoding, etc.) of 5-or-more channels each. This is for active loudspeaker projects with outboard crossover(s) so I don't need any signal processing or decoding. Thanks for the offer (@Michael Chua) but I want to steer clear of fan-cooled (pro) amps.
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Old 26th January 2017, 08:50 PM   #5
rsavas is offline rsavas  Canada
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For Class "D" try tpa3251d2
Member "gmarsh" has been building them for a group buy. they are a smt design.
He has basically finished his first group buy for these set of modules. I think that he is tired of assembling them by hand but if you are able to solder them up I would think that it is a very economical approach. I have only used the TPA3100d2 and tpa3118, they are decent, not class AB sound quality, but I have not heard the improved TPA3251 yet.
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Old 26th January 2017, 08:59 PM   #6
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by rsavas View Post
For Class "D" try tpa3251d2
Member "gmarsh" has been building them for a group buy. they are a smt design.
He has basically finished his first group buy for these set of modules. I think that he is tired of assembling them by hand but if you are able to solder them up I would think that it is a very economical approach. I have only used the TPA3100d2 and tpa3118, they are decent, not class AB sound quality, but I have not heard the improved TPA3251 yet.
I outlined my struggles with (trying to) build something. I have lots of parts, just can't put it all together in a nice case, or cases, for this many channels.

At this point I'm looking for commercial product recommendations.
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Old 26th January 2017, 09:08 PM   #7
rsavas is offline rsavas  Canada
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Yes, I read your initial post but I think that you were assuming a DIY Class "AB" amp build. Yes for that power ratings it is massive
A class "D" build is going to be a lot simpler than a Class "AB" build IMO.
1) A AC/DC SMPS, ~meanwell or equiv.
2) Class "D" modules
3) case, connectors.
You are going to spend a lot more $ if you have to resort to buying something already made.
I guess you could by an old multi-channel A/V receiver, people are dumping them for cheap, when everything switched to HDMI. I do not think that they will deliver the power that you are asking for however.

Good Luck

Last edited by rsavas; 26th January 2017 at 09:13 PM.
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Old 26th January 2017, 09:22 PM   #8
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by rsavas View Post
Yes, I read your initial post but I think that you were assuming a DIY Class "AB" amp build. Yes for that power ratings it is massive
A class "D" build is going to be a lot simpler than a Class "AB" build IMO.
1) A AC/DC SMPS, ~meanwell or equiv.
2) Class "D" modules
3) case, connectors.
You are going to spend a lot more $ if you have to resort to buying something already made.
I guess you could by an old multi-channel A/V receiver, people are dumping them for cheap, when everything switched to HDMI. I do not think that they will deliver the power that you are asking for however.

Good Luck
I built a pair of 4-channel class-D amplifiers using switching power supplies a couple of years ago and one of them has suffered from interference that produces noises in the audio spectrum. That has made me a bit gun-shy about most of the class-D modules out there, including the ones you mentioned.

Maybe I should try again instead of spending $2k on commercial amps... I'm very torn on what to do, honestly. I like DIY but I don't want to make something crappy looking that doesn't perform well.
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Old 28th January 2017, 12:22 AM   #9
maiko is offline maiko  Finland
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Hi Charlie, how about telling what amplifier kits and parts you have left maybe people here can help and encourage you to finish your project.
Don't think if you are going into DIY mode you have to make every screw by yourself, there are lots of beautiful DIY audio cases on eBay and AliExpress, but if you want to get up an running quickly and cheap then I would suggest as Rsavas buying a used A/V multichannel amp dirt cheap, just anything and get on evaluating and modding your speaker project.
What's your project actually about, I visited your homepage which I think had some cool stuff regarding linux audio etc., I am thinking myself contemplating over a small 2 or 3 way active loudspeaker project, I guess that's what you are going to do too?
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Old 28th January 2017, 12:59 AM   #10
CharlieLaub is offline CharlieLaub  United States
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Quote:
Originally Posted by maiko View Post
Hi Charlie, how about telling what amplifier kits and parts you have left maybe people here can help and encourage you to finish your project.
Don't think if you are going into DIY mode you have to make every screw by yourself, there are lots of beautiful DIY audio cases on eBay and AliExpress, but if you want to get up an running quickly and cheap then I would suggest as Rsavas buying a used A/V multichannel amp dirt cheap, just anything and get on evaluating and modding your speaker project.
What's your project actually about, I visited your homepage which I think had some cool stuff regarding linux audio etc., I am thinking myself contemplating over a small 2 or 3 way active loudspeaker project, I guess that's what you are going to do too?
Thanks for the encouragement. The problem for me is the scope is too large.

I don't have experience building amplifiers, OK well I did build two 4-channel IRS2092 class-D amps and some LM3886 chip amps, PS, etc. But that was more like wiring it all together. Now I am faced with more construction challenges related to heat sink mounting, inrush limiting, chassis building, etc. I did look at some chassis from DIY audio but since I have 5 channels per side putting it in one case per side means a really large one. I could go to two chassis per side but then the costs are mounting up. And I still would need to do some fabrication work and all the assembly, and then start testing. The amp boards are L12-2 and L20se class-AB amps, the former for 4 ch into 8R and then one ch of the latter into 4R. I have some 400VA toroidal transformers with 33-0-33 secondaries and a gaggle of 50V, 46kuF caps for the PS. I have a bunch of heaksinks that the amp boards should fit on as well and I have some ideas about mounting. But putting all that together (physical assembly) takes time and I can really only work with wood and some basic drill/tap type metal working. I am afraid I will end up with some kind of ugly mess! I am also concerned that once I assemble everything I will not be able to test it out, will run into some problems, etc. That all find and good and I can move past that, but all of this stands in between me and loudspeaker building, which is what I really want to be doing. At this point I would rather buy some good quality multichannel commercial amps so that I can move on to the "fun stuff" and then I can return to amp building later or not be so worried if it starts out as a bunch of parts on a piece of plywood that I can play around with until I get the amp working well. At this point I am not really comfortable pulling the trigger on hundreds of dollars of chassis although I may do that at some point when I am more confident in what I am doing and the amp kits themselves. I wasn't originally intending to build stand alone amplifiers, but instead to build the amps into my loudspeakers. This makes sense when your loudspeaker is a BOX and you can put a heatsink on the back and the PS and amp board inside. But I am not building boxed loudspeakers currently, and this has kind of thrown a wrench into the amp plans.

To answer your question, I am (trying to) build two open baffle systems, each needing 5-channels per side. One has three 8" woofers in a planar baffle, plus mid, and tweeter. The other is larger with two 12" subwoofers in an H-frame, and a planar baffle with a 15" pro woofer, 6" mid and tweeter. These will require a lot of work to take measurements and then develop the crossover. I need for the amplifiers to remain constant throughout and the amplification requirements are the same for both systems. Thus I might just buy a pair of amps so that I can move ahead with the loudspeaker plans. I have some closed/vented speaker projects slated, but these will come later and need only 2- or 3- channels per speaker. I plan to build in the amps like I described, and may try to make a standalone amp after that.
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