@jwdevos
Awesome idea about active crossover and processing my surround sound I've looked at some of these standalone processors and they are ridiculous in price I have thought about using my PC the process this but this is going into a newly built addition that I'm working on and I want to keep things pretty user friend to the family which is not as technical as I am but then my new lab is right on the other side of the wall I could also experiment with some things having a Chase through the wall with patch cords power my amp I'm really loving all the input in this community thanks guys
Awesome idea about active crossover and processing my surround sound I've looked at some of these standalone processors and they are ridiculous in price I have thought about using my PC the process this but this is going into a newly built addition that I'm working on and I want to keep things pretty user friend to the family which is not as technical as I am but then my new lab is right on the other side of the wall I could also experiment with some things having a Chase through the wall with patch cords power my amp I'm really loving all the input in this community thanks guys
Not a bad idea. If you're going that route I highly recommend keeping an eye out for a used Mac mini. I've picked up a couple of the late 2012 models for about $40-50/each from my local electronics recycler. The minis are super quiet. They do have a fan, but Apple has a patent on how to shape the fan blades to make the fans virtually silent. That's important in an audio application.
... or get a fan-less PC. Intel NUC maybe? Raspberry Pi?
I had a Focusrite Saffire running as the XO for my LXmini for a while. I used Reaper and ReaEQ for the DSP work.
Tom
I am using a Dell optiplex mini fanless PC low power to power my home assistant smart home controls and it's been absolutely beautiful and 10 times more power than I actually need I could probably implement something like that for what you're talking about Tom. I don't have a very good understanding of preamps and the processing and of things but then most of that is all software and there's plenty of pre-written software out there to achieve this.
Mike H and Tom,
looping back to the Mean Well power supply question:
I dug back into my dusty archives for the investigation of the Mean Well RPS400 that I did in mid-2019. I believe I posted the results then, or passed them on to Tom to post. Long ago, BC - Before Covid.
At low current consumption, the MW supply goes into what I'll call a pulse mode (perhaps not the correct technical term in the switching supply world) . The supply can't run continuously as there's no load to dissipate the output generated. In this mode, the supply kicks on briefly until the output voltage gets roughly to the nominal Vout plus the Vout's tolerance spec and then turns off until the output voltage drops below the low end of the tolerance band. This pulsing on/off happens in the several kHz range depending on the exact setting of the output voltage trim potentiometer and load conditions.
The best (?) case is if you crank the Vout trim to the max, almost exactly 40V, but even there you need to draw about 400mA (i.e., ~100 Ohm load). If the quiescent consumption of your load (i.e., the Modulus amps or whatever), isn't sufficient to get the MW supplies out of pulse mode, then you'll need to add a bit of resistance across the supply outputs to tame it.
Curiously, I did not determine what resistance/load I needed to add to the supply at its nominal 36V output in order to get into continuous operation. I believe that's because at the time, having arrived at a solution and being not that concerned about running an LM3886-based amp at +/-40V (regulated), I didn't dig in further. I'm sure some additional quiescent current draw via the amplifier modules and/or extra resistor loading will solve the problem at Vout=36V. I note that Tom doesn't appear to spec the no-signal quiescent current consumption of his amps, though, admittedly, that is usually not something folks care about. You can get pretty close by looking at the nominal quiescent current of on the datasheet of the LM3886 and the other active components on the board and doing a little arithmetic.
I believe other folks have looked at other MW supplies in the RPS400 series (and lower-power series) and have found this behavior appears only in the RPS400-36, not RPS400-27 and others. I expect that all of the various RPS models can exhibit this behavior as I expect them to have almost-identical circuit topologies, differing only in the components that scale based on power output and output voltage. However, if the loading conditions are favorable relative to the supplies' thresholds for low-output pulse operation, then they will appear to not have issues.
looping back to the Mean Well power supply question:
I dug back into my dusty archives for the investigation of the Mean Well RPS400 that I did in mid-2019. I believe I posted the results then, or passed them on to Tom to post. Long ago, BC - Before Covid.
At low current consumption, the MW supply goes into what I'll call a pulse mode (perhaps not the correct technical term in the switching supply world) . The supply can't run continuously as there's no load to dissipate the output generated. In this mode, the supply kicks on briefly until the output voltage gets roughly to the nominal Vout plus the Vout's tolerance spec and then turns off until the output voltage drops below the low end of the tolerance band. This pulsing on/off happens in the several kHz range depending on the exact setting of the output voltage trim potentiometer and load conditions.
The best (?) case is if you crank the Vout trim to the max, almost exactly 40V, but even there you need to draw about 400mA (i.e., ~100 Ohm load). If the quiescent consumption of your load (i.e., the Modulus amps or whatever), isn't sufficient to get the MW supplies out of pulse mode, then you'll need to add a bit of resistance across the supply outputs to tame it.
Curiously, I did not determine what resistance/load I needed to add to the supply at its nominal 36V output in order to get into continuous operation. I believe that's because at the time, having arrived at a solution and being not that concerned about running an LM3886-based amp at +/-40V (regulated), I didn't dig in further. I'm sure some additional quiescent current draw via the amplifier modules and/or extra resistor loading will solve the problem at Vout=36V. I note that Tom doesn't appear to spec the no-signal quiescent current consumption of his amps, though, admittedly, that is usually not something folks care about. You can get pretty close by looking at the nominal quiescent current of on the datasheet of the LM3886 and the other active components on the board and doing a little arithmetic.
I believe other folks have looked at other MW supplies in the RPS400 series (and lower-power series) and have found this behavior appears only in the RPS400-36, not RPS400-27 and others. I expect that all of the various RPS models can exhibit this behavior as I expect them to have almost-identical circuit topologies, differing only in the components that scale based on power output and output voltage. However, if the loading conditions are favorable relative to the supplies' thresholds for low-output pulse operation, then they will appear to not have issues.
I believe @sledwards12375 did quite a bit of experimenting around that time too. If I recall correctly, he tried various load resistors, including some mounted on the heat sinks because the power dissipation was getting up there. We went back/forth on this for a while but never found a good solution that way.
Then you pointed out that if you increased the output voltage to 40 V the whining would stop. I suggested that to those who were having issues with whiny supplies and it solved their issue. So I think it's worked in 3-4 cases.
Oddly enough I never had issues with the RPS-400-36. I can't remember how many of them I tried, though. It could just have been one pair, so maybe I got lucky like the ~50% or so other folks who bought that supply. I've gone through 12-14 of the RPS-400-27 without issue.
I received a response from Mean Well regarding the LOP-600-36. It's the same topology as the RPS series so it may/may not whine. They didn't answer my question regarding minimum load but just said to try it... That doesn't give me a lot of confidence.
A single Modulus-686 draws about 350 mA so you'd think a stereo pair would load the supplies plenty.
Tom
Then you pointed out that if you increased the output voltage to 40 V the whining would stop. I suggested that to those who were having issues with whiny supplies and it solved their issue. So I think it's worked in 3-4 cases.
Oddly enough I never had issues with the RPS-400-36. I can't remember how many of them I tried, though. It could just have been one pair, so maybe I got lucky like the ~50% or so other folks who bought that supply. I've gone through 12-14 of the RPS-400-27 without issue.
I received a response from Mean Well regarding the LOP-600-36. It's the same topology as the RPS series so it may/may not whine. They didn't answer my question regarding minimum load but just said to try it... That doesn't give me a lot of confidence.
A single Modulus-686 draws about 350 mA so you'd think a stereo pair would load the supplies plenty.
Tom
Hey guys it's been a minute since I've posted on here I've been slowly working on my five channel amplifier just finishing up building my power modules. I may have asked this question in the past but I'll ask it again I have a dilemma if I go with five 686 modules I start to have a space and budget issue. Leaning more towards this being a space issue then cost. I'm also looking at the 286 modules as well which are about $150 cheaper. Here's my thoughts I am considering the 686 for front left and right and the remaining channels 286. My real question here is heaven substantial different amounts of power is this going to be an issue for my surround sound. Most of the power is driven from my front left and right when it comes to loud noises and most of the dialogue from my front center channel. With running room correction I would imagine my processor will make adjustments to balance out anything as far as my front speaker sounding louder than everything else. Mainly I just want that extra power for music not so much for the surround sound I want to be able to jam out and enjoy a rock concert in my living room lol. Just looking for any thoughts or input on going with two different wattages in the system. I've researched a little bit of off-the-shelf AVR systems and the wattage seems to be evenly distributed over all channels. I really like what Tom has to offer here with these modules but of course that comes with the price which I'm not upset about I understand the cost of building me all the components and everything cost money if you want quality.
I am making a 5 channel amp for my AV system. I haven't yet put the chassis together so I haven't yet determined how well it will work. I used all Mod86 boards. I have JBL Studio 530's in a medium sized room. They can get much louder than I would ever want to listen running off the AVR. If the AVR can power the speakers that much, 5 Mod86's are going to be fine.
It largely depends on the speaker you have. Always concider the center the most important one. If you use HIFI speaker, a good system would serve the 3 front speaker (L-C-R) with the large 686 amps. The other channels, ( for example in my case 6 of them), should play well with a single 286 if the speakers are not to power hungry.
I tried a single LM3886 with a typical, older ADS/Braun 3-way. For live sound reproduction this was clearly on the weak side. A good thing about the LM3886, they don't sound ugly if driven to the limit, it is more like they don't get louder. So for side, rear and top etc. they should work well.
Please do not compare an AVR 1:1 with an external amp!
The power of your AVR, for all 7 channels may be 50W each, but if you only use 1 or 2 cannels, the AVR will give you 150W or more. The AVR shares a small power supply with many amps. Something a good amp designer would not do. With home cinema use and separate subwoofer, this works quite well.
Now, if you got a "normal" high quality amp, it is good design practice to have a PS that can deliver the RMS output for a long time, even endless.
What is the point? With a 50W quality amp, you are limited by the PS voltage. The AVR on the opposite side, if the remaining channels don't ply too loud, is able to give a short burst to a demanding channel, sometimes 3-times the 7 channel power.
So if you replace a 7x50W AVR with seven conventional 50W amps, the separate amps may sound less dynamic.
Conlusion, if you want to replace the AVR amps with separate amps, they should have at least the power of the AVR in 1 or 2 channel mode.
Look at the 1 or 2 channel power of your AVR and you will understand better.
A good idea is to replace the 3 main channels of your AVR by high quality, high power amps. The remaining amps of the AVR will have much more power and sound better that way, so maybe no urgend need for the small amps.
Next to replace, IMO, are the rear speaker. The height stuff seems to draw very little power. Depends on your configuration, of course.
I tried a single LM3886 with a typical, older ADS/Braun 3-way. For live sound reproduction this was clearly on the weak side. A good thing about the LM3886, they don't sound ugly if driven to the limit, it is more like they don't get louder. So for side, rear and top etc. they should work well.
Please do not compare an AVR 1:1 with an external amp!
The power of your AVR, for all 7 channels may be 50W each, but if you only use 1 or 2 cannels, the AVR will give you 150W or more. The AVR shares a small power supply with many amps. Something a good amp designer would not do. With home cinema use and separate subwoofer, this works quite well.
Now, if you got a "normal" high quality amp, it is good design practice to have a PS that can deliver the RMS output for a long time, even endless.
What is the point? With a 50W quality amp, you are limited by the PS voltage. The AVR on the opposite side, if the remaining channels don't ply too loud, is able to give a short burst to a demanding channel, sometimes 3-times the 7 channel power.
So if you replace a 7x50W AVR with seven conventional 50W amps, the separate amps may sound less dynamic.
Conlusion, if you want to replace the AVR amps with separate amps, they should have at least the power of the AVR in 1 or 2 channel mode.
Look at the 1 or 2 channel power of your AVR and you will understand better.
A good idea is to replace the 3 main channels of your AVR by high quality, high power amps. The remaining amps of the AVR will have much more power and sound better that way, so maybe no urgend need for the small amps.
Next to replace, IMO, are the rear speaker. The height stuff seems to draw very little power. Depends on your configuration, of course.
If the primary use case is music reproduction, I would go with the Modulus-686 on the left and right channels. Modulus-286 on the centre channel for sure and maybe for the remaining surround channels as well. The Modulus-86 would likely work well for the surrounds as well. I don't think there's ever a lot of information in the surround channels.
I'd use the Modulus-686 on the subwoofer as well if you have one.
But as pointed out above, the amount of power needed depends a lot on the size of your listening space, your speakers, and your preferences around SPL. I had a larger listening space in my previous house. It was maybe 35 m^2 in an L shape. I did find that my somewhat inefficient KEF R700 speakers (8 Ω, 85 dB @ 1 W, 1 m AFAIR) sounded better with the Modulus-686 than with the Modulus-286, even though the 50-60 W afforded by the Modulus-286 should be plenty.
At my current place the listening room is smaller and I sit closer to the speakers, so I'm curious to see if I'll get any benefit of the Modulus-686. I need to build one as I sold the one I was using.
Tom
I'd use the Modulus-686 on the subwoofer as well if you have one.
But as pointed out above, the amount of power needed depends a lot on the size of your listening space, your speakers, and your preferences around SPL. I had a larger listening space in my previous house. It was maybe 35 m^2 in an L shape. I did find that my somewhat inefficient KEF R700 speakers (8 Ω, 85 dB @ 1 W, 1 m AFAIR) sounded better with the Modulus-686 than with the Modulus-286, even though the 50-60 W afforded by the Modulus-286 should be plenty.
At my current place the listening room is smaller and I sit closer to the speakers, so I'm curious to see if I'll get any benefit of the Modulus-686. I need to build one as I sold the one I was using.
Tom
As always thanks for your input everyone everyone kind of confirmed what I was thinking myself and I already have a powered subwoofer that I'm going to use which works out well for me. I'm out of town for work wife called me yesterday and said a big package showed up I'm excited cuz I know that's my chassis that I ordered and I believe my transformer is going to be here by the end of the week so things are moving along pretty well I'll post some pictures as I'm assembling things and laying things out
I finally got my chassis and transformer came in on the beginning of the week I was out of town for work all week and just counting the days to come home and start mocking everything up. As you can see I don't have the amp modules yet but I made cardboard for now in those dimensions just to see how things fit. I've got the 686 modules towards the bottom of the heat sink figured that would help dissipate heat better towards the bottom as heat rises and the smaller modules along the top. I started considering maybe this would be an issue causing the other modules to heat up and changing performance but then when I'm in five channel mode I'm watching movies and it's not a continuous output or working things very hard the only time I'm going to be really pushing the limits is into channel mode which wouldn't matter then. The transformer is a 1000 volt amp I had custom-made with a 12 volt tap as well just in case I want to add any sort of electronics inside . Transformer might be a tad undersize but once again when I'm using 5 channels I'm really not using a whole lot of power probably only 5 10 watts Max per module. Just to save room I'll have to stack some of my power supply modules that I built but it looks like they'll fit really nice I just need to get longer standoffs to make that happen. Once I finalize my layout I'm probably going to start permanently mounting some things in there or at least making more permanent decisions on placement and hopefully very soon I can order these modules
Attachments
Both the layout and the transformer power rating make sense to me. Here's a very similar amp: https://ncforo.com/index.php?threads/power-amp-picture-gallery.7/post-42
I've built a similar amp for a client, except the one I built had four channels of Modulus-686. Pretty sweet amp.
Tom
I've built a similar amp for a client, except the one I built had four channels of Modulus-686. Pretty sweet amp.
Tom
looks awesome tom. i tried to enlarge the pics but i need to sign up to that site to see closer up. i hope everyone is having a great holiday if you observe Easter. if not have a great Sunday!
I've got a question for you Tom so I built my own power modules use all high quality parts and all that just found the pre-printed circuit board and I made the decision to go with a lug type terminal to terminate my power feed in and feed out. Being an electrician 27 years I understand that those could be prone to fail and soldering the wiring in is the way to go obviously there's a trade off there if I wanted the service the unit it's going to be a more pain in the *** but I'm looking to go as solid as possible on this build. So I'm removing these terminals. My question is when I order the amp modules can I get those without the plug that is provided on the board or can I just order the harness separately solder my end plug your end in. Same question kind of goes for the balanced input and speaker output I bought some shielded balance cable that I've already soldered onto my back panel I'm starting to wonder how this is going to work me terminating the other end will I need to buy some tools to terminate that or could I just solder it right to the board. The way I see it it doesn't hurt to solder it eliminates problems especially on the preamp side amplifiers going to amplify everything even a week possible connection. I understand I'm totally overthinking this but I'm over engineering my dream app right now.