Hi guys.
I am currently building a fully active three way plus stereo sub system. This is my first real DIY audio adventure and quite a large undertaking – but I am learning a lot and loving it as a new hobby (it’s winter and rolling around under my car isn’t as much fun in the rain and cold!).
I have a MiniDSP 2x8 which will be acting as the pre-amp/crossover/EQ/time-alignment in the audio chain. I have also just ordered a Dayton EMM-6 calibrated mic to use with a newly purchased E-Mu 0404 USB sound card for measurement of room/speakers etc.
The speakers will have the following drivers:
Tweeters: SB Acoustics SB29RDNC-C000-4 [4 ohm neo ring radiator]
Mids: SB Acoustics SB15NRXC30-4 [4 ohm 5”]
Woofers: SB Acoustics SB29NRX75-6 [6 ohm 10”]
Subs: Peerless XLS [8 ohm 10” with 10” 400g passive radiators]
To power these I will need 8 channels of amplification. I originally started looking at HifimeDIY amps about a year ago because of the price and ease of use. I wanted to just plug a meanwell into them and get going. Now I have been lurking enough and reading up on matters I am braver and more proficient with a soldering iron I decided that I would like a kit so I can hand on heart say to people: I made this!
To this end I ordered 4 stereo pairs of ljm_ljm’s L25d. Why the L25d? Because I have only read good things about their sound quality, noise floor, distortion etc etc. Also because they can provide the sub-woofers power handling of 250w into 8 ohm when given high voltage, but have the current capability to drive my 4/6 ohm woofers when used with lower supply voltages. This makes the finished boards more flexible in the long run. It also means (hopefully) that I will be able to scale the power by selecting the power supply for each driver. Obviously the amps are capable of WAY over-powering the drivers but I think that a little self control with the volume knob and lots of extra head-room in terms of power can only be a good thing! I know I have ordered a LOT of power for the mids and tweeters but hope I can scale back by selecting lower voltage supplies and reduce the heat/distortion that comes from the high voltage supplies.
So: onto my question: Can you please help me choose power supplies for my amps? I am basically decided on Connexelectronics regulated SMPS line, but need to choose which exact ones are most suitable for my application.
I am thinking about an SMPS 800R at 70 volts for the sub-woofer amps, an SMPS 500R (voltage undecided) for the [6 ohm 200 watt handling] woofers and a shared SMPS 500 R (voltage un-decided) to power the boards for the tweeters and mids. Later on I could upgrade by buying an SMPS 300R for the tweeter amps maybe?
Can you please talk me through the descision process and choose the right power supplies?
Many thanks for taking the time to read this and I look forward to everyone’s input.
Kind regards,
Jai Stanley
I am currently building a fully active three way plus stereo sub system. This is my first real DIY audio adventure and quite a large undertaking – but I am learning a lot and loving it as a new hobby (it’s winter and rolling around under my car isn’t as much fun in the rain and cold!).
I have a MiniDSP 2x8 which will be acting as the pre-amp/crossover/EQ/time-alignment in the audio chain. I have also just ordered a Dayton EMM-6 calibrated mic to use with a newly purchased E-Mu 0404 USB sound card for measurement of room/speakers etc.
The speakers will have the following drivers:
Tweeters: SB Acoustics SB29RDNC-C000-4 [4 ohm neo ring radiator]
Mids: SB Acoustics SB15NRXC30-4 [4 ohm 5”]
Woofers: SB Acoustics SB29NRX75-6 [6 ohm 10”]
Subs: Peerless XLS [8 ohm 10” with 10” 400g passive radiators]
To power these I will need 8 channels of amplification. I originally started looking at HifimeDIY amps about a year ago because of the price and ease of use. I wanted to just plug a meanwell into them and get going. Now I have been lurking enough and reading up on matters I am braver and more proficient with a soldering iron I decided that I would like a kit so I can hand on heart say to people: I made this!
To this end I ordered 4 stereo pairs of ljm_ljm’s L25d. Why the L25d? Because I have only read good things about their sound quality, noise floor, distortion etc etc. Also because they can provide the sub-woofers power handling of 250w into 8 ohm when given high voltage, but have the current capability to drive my 4/6 ohm woofers when used with lower supply voltages. This makes the finished boards more flexible in the long run. It also means (hopefully) that I will be able to scale the power by selecting the power supply for each driver. Obviously the amps are capable of WAY over-powering the drivers but I think that a little self control with the volume knob and lots of extra head-room in terms of power can only be a good thing! I know I have ordered a LOT of power for the mids and tweeters but hope I can scale back by selecting lower voltage supplies and reduce the heat/distortion that comes from the high voltage supplies.
So: onto my question: Can you please help me choose power supplies for my amps? I am basically decided on Connexelectronics regulated SMPS line, but need to choose which exact ones are most suitable for my application.
I am thinking about an SMPS 800R at 70 volts for the sub-woofer amps, an SMPS 500R (voltage undecided) for the [6 ohm 200 watt handling] woofers and a shared SMPS 500 R (voltage un-decided) to power the boards for the tweeters and mids. Later on I could upgrade by buying an SMPS 300R for the tweeter amps maybe?
Can you please talk me through the descision process and choose the right power supplies?
Many thanks for taking the time to read this and I look forward to everyone’s input.
Kind regards,
Jai Stanley
Hi Jai,
I'd start with an SMPS for the subwoofers, and just one SMPS for the three-way (most power is required for the woofer).
IMO it does not make much sense to cut power for a mid-high; the amps will not clip during normal use (hard clipping is mostly responsible for blown mids and tweeters).
When not satisfied you might add power supplies, but with one power supply and some additional capacitive decoupling for every amp board you might easily get there.
I'd start with an SMPS for the subwoofers, and just one SMPS for the three-way (most power is required for the woofer).
IMO it does not make much sense to cut power for a mid-high; the amps will not clip during normal use (hard clipping is mostly responsible for blown mids and tweeters).
When not satisfied you might add power supplies, but with one power supply and some additional capacitive decoupling for every amp board you might easily get there.
Thank you for the replies. I am beginning to get a better picture of my requirements..
I sat and re-read the L20D thread last night. It appears I need to change a few resistors on the board according tho the IRAudio reference design in order to change the min/max voltage of the amp. I had previously assumed that as LJM didn't include under/over voltage protection in the amp, I could just use a lower supply voltage without doing anything else. Also, the L25D differs from the L15d/L20d in that it isn't an exact implementation of the IRS design. I would need to cross reference the IRS design with the reverse engineering other forum members have already done.
So I have two options:
1: Change these resistors and go with the power supplies I mentioned before.
2: Use the higher supply voltages and not worry about the power output.
As I mentioned I am not too worried about having too much power for my mids and tweeters. Just because an amp CAN supply too much power, I would run out of power to the woofers first and turn the volume down. My car has 320 horse-power and yet I am perfectly able to drive to the shops at 30 mph!
So: Am I right in the following thinking:
I should go for a high voltage amp to drive my subs as they are 8 ohm. This will mean the amp has to dissipate lots of heat and I should probably put larger heat-sinks on them. Possibly put them into a Hifi2000 case with heat-sinks and use copper slugs/heat-pipes to take the heat to the large sinks on the side of the case?
For the 4 ohm Mids and tweeters, and probably the 6 ohm woofers, I will need more current. From what I can gather the L25D will perform better and produce more power and less distortion into these with the lower voltage power supply. To this end I would need a PSU capable of supplying a lot of current.
So:
An SMPS800R +/- 72v, 230VAC, 12V acc for the subs.
An SMPS2000R +/- 60v, 230VAC, 12V acc for everything else.
Comes to $290 plus shipping.
How About:
An SMPS800R +/- 72v, 230VAC, 12V acc for the subs.
An SMPS800R +/- 60v (adjusted to 66v), 230VAC, 12V acc for the Woofers.
An SMPS800R +/- 60v, 230VAC, 12V acc for the Tweeters and Mids.
Comes to $300 plus shipping, so no real difference.
Will I be better off with more supplies to take the strain of the woofers from the power supply for the higher frequency amps?
Would I have noise/supply issues running four channels from one power supply? Would I need capacitive de-coupling that was mentioned, and how do I sec that?
Thank you all for your help!
Perhaps Christi could comment as I am reasonably confident I will be placing an order there soon.
Kind regards,
Jai Stanley
I sat and re-read the L20D thread last night. It appears I need to change a few resistors on the board according tho the IRAudio reference design in order to change the min/max voltage of the amp. I had previously assumed that as LJM didn't include under/over voltage protection in the amp, I could just use a lower supply voltage without doing anything else. Also, the L25D differs from the L15d/L20d in that it isn't an exact implementation of the IRS design. I would need to cross reference the IRS design with the reverse engineering other forum members have already done.
So I have two options:
1: Change these resistors and go with the power supplies I mentioned before.
2: Use the higher supply voltages and not worry about the power output.
As I mentioned I am not too worried about having too much power for my mids and tweeters. Just because an amp CAN supply too much power, I would run out of power to the woofers first and turn the volume down. My car has 320 horse-power and yet I am perfectly able to drive to the shops at 30 mph!
So: Am I right in the following thinking:
I should go for a high voltage amp to drive my subs as they are 8 ohm. This will mean the amp has to dissipate lots of heat and I should probably put larger heat-sinks on them. Possibly put them into a Hifi2000 case with heat-sinks and use copper slugs/heat-pipes to take the heat to the large sinks on the side of the case?
For the 4 ohm Mids and tweeters, and probably the 6 ohm woofers, I will need more current. From what I can gather the L25D will perform better and produce more power and less distortion into these with the lower voltage power supply. To this end I would need a PSU capable of supplying a lot of current.
So:
An SMPS800R +/- 72v, 230VAC, 12V acc for the subs.
An SMPS2000R +/- 60v, 230VAC, 12V acc for everything else.
Comes to $290 plus shipping.
How About:
An SMPS800R +/- 72v, 230VAC, 12V acc for the subs.
An SMPS800R +/- 60v (adjusted to 66v), 230VAC, 12V acc for the Woofers.
An SMPS800R +/- 60v, 230VAC, 12V acc for the Tweeters and Mids.
Comes to $300 plus shipping, so no real difference.
Will I be better off with more supplies to take the strain of the woofers from the power supply for the higher frequency amps?
Would I have noise/supply issues running four channels from one power supply? Would I need capacitive de-coupling that was mentioned, and how do I sec that?
Thank you all for your help!
Perhaps Christi could comment as I am reasonably confident I will be placing an order there soon.
Kind regards,
Jai Stanley
Peerless XLS 10" Passive Radiator (830481)
Parameter Value
Fs 13.7 Hz
Qms 11.4
Vas 80 l
Rms 2 Kg/s
Mms 265g
Cms 0.508 mm/N
Sd 333 cm2
xmax 22 mm
i would like to suggest SMPS800R with L25D for the sub. as for the speaker 8 ohm, amp will not produce too much heat i think, because amp running in class D mode. I have with me Iraudump 7D original from international rectifier also run with irs2092 chips. They sound good. mosfet output not produce much heat, but aux supply for +12v will produce more heat than mosfet.
and smps1kw + 2 L15D for the woofer + mid and Tweeter.
we should not choose amp rated more than 70% of the speaker power rms. can cause damage to the speaker . This is my suggestion only i think its enough power for them.
Parameter Value
Fs 13.7 Hz
Qms 11.4
Vas 80 l
Rms 2 Kg/s
Mms 265g
Cms 0.508 mm/N
Sd 333 cm2
xmax 22 mm
i would like to suggest SMPS800R with L25D for the sub. as for the speaker 8 ohm, amp will not produce too much heat i think, because amp running in class D mode. I have with me Iraudump 7D original from international rectifier also run with irs2092 chips. They sound good. mosfet output not produce much heat, but aux supply for +12v will produce more heat than mosfet.
and smps1kw + 2 L15D for the woofer + mid and Tweeter.
we should not choose amp rated more than 70% of the speaker power rms. can cause damage to the speaker . This is my suggestion only i think its enough power for them.
I can't imagine the mids/tweets demanding the current; as you said the woofers and/or their amps will run out of gas sooner.
And if that current were to flow in the mids/tweets it would fry them in short order.
My personal opinion is to drive all channels equally with identical supplies to isolate the pairs from noise and possible damage. Probably not the cheapest solution either, sorry. Might get a price break though. If one large SMPS bit the dust, it could smoke the entire setup. Not to mention smaller SMPS's keep them each loaded in the higher effieciency zone.
I would prefer to make something with equal capabilities across the board, even if you don't need it. Imagine an emotiva / outlaw amp or other brand that had 8 channels of different nameplate powers? They don't really exist. I am the kind to pay extra today for what I might need tommorrow. This is my opinion.
I would do either the 800R or 600R's across the board for each pair. I would make a remote adjustment of the SMPS output voltage for each, kind of like a gain knob for the SMPS. Also install manual volume knobs to limit each output too. You are doing it all digitally, in my past experience with my PC, weird crap happens with the audio when codecs do not work resulting in loud noise / static. Without limits in place it can destroy speakers.
I would prefer to make something with equal capabilities across the board, even if you don't need it. Imagine an emotiva / outlaw amp or other brand that had 8 channels of different nameplate powers? They don't really exist. I am the kind to pay extra today for what I might need tommorrow. This is my opinion.
I would do either the 800R or 600R's across the board for each pair. I would make a remote adjustment of the SMPS output voltage for each, kind of like a gain knob for the SMPS. Also install manual volume knobs to limit each output too. You are doing it all digitally, in my past experience with my PC, weird crap happens with the audio when codecs do not work resulting in loud noise / static. Without limits in place it can destroy speakers.
Last edited:
Presumably every amp channel has a protection circuit.
And what higher efficiency zone?
At normal listening levels most of the power is idle power, and that increases for every extra PS.
That's exactly what you get with a common PS, which also has much higher reserves to supply the woofer channels than individual supplies.
A compromise would be separate PS's with appropriate ratings for the woofers and mid/tweets.
I am assuming any one component failure in a SMPS can casue uncontrolled UV or OV output. In this case the amplifier protection is a mute point as the L25D has no speaker protection on board. Only UV and OV protection on the front end. My point to make is, there is substantially higher voltages present in a SMPS and the amplifier shutting down prior serves no purpose when the fets smoke due to OV. I am sure with SMPS electronics do fail. Ever head of one failing?
http://www.diyaudio.com/forums/power-supplies/201468-faulty-connexelectronic-smps2000r.html
http://www.diyaudio.com/forums/power-supplies/198228-smps-blown-when-connected-mains.html
My assumption is that there is better efficiency when loaded higher? am I wrong? I assumed most electronics power supplies got better % with load? Maybe I'm wrong? I'll check my books
Ok, since there are almost no idle power specs stated. It does make sense, at some point there is a cross over on 1 large vs ?? small SMPS idle currents.
Next time I will keep my opinion to myself. I was trying to offer my opinion to the OP, which is incorrect in your eyes. My bad. i wil keep my opinion to myself along with my plans and projects.
Last edited:
Does a common power supply introduce intermodular distortion or noise in any way in these circuits? I've always thought (sorry, assumed) that using a common power source wasn't as good for distortion or noise. Having a single power supply would certainly help with packaging in a single case, but I admit it does reduce redundancy, dafety and (possibly in the long term) flexibility. Looks like it would be about half the price of four SMPS800R too. How do the 'QR' supplies fair against the 'R'? At 75 volts, it probably wouldn't matter if the supply voltage sagged by the 5% Connexelectronics quote in the documentation..
Jai
Jai
My fault for not being clear; I meant an outboard speaker protection circuit like this one recommended by LJM:
Stereo speaker protection board-sc | eBay
Correct, so the more PS the less,load each and the lower the efficiency.
I don't know about the ones you're looking at, but IIRC the 1000 W Connex SMPS is 4 or 5 W.
help with PS voltage for L25D
I have a similar question to the o/p...
I would like to build two 4-channel amps with around 100W per channel output into 8 ohms. The L15D and L25D designs by LJM look very nice and I am leaning in that direction.
My problem concerns the power supply - I'd like to use a linear PS. I currently have a 40-0-40V 1kVA transformer and can get another one (the amps will be in separate enclosures), but this would result in rail voltages around +/-55V. The primary is spec'd at 115V, so I might get a tiny bit more voltage if the AC main is at 120V. But I am afraid it will still be below the minimum recommended rail voltages of +/- 60V for the L25D. I'd like to use it because it has two output devices.
Will these rail voltages cause UV protection to kick in (I believe that the L25D has that)?
Any other ideas that would allow me to use a 40-0-40 transformer with four L25D amps?
-Charlie
I have a similar question to the o/p...
I would like to build two 4-channel amps with around 100W per channel output into 8 ohms. The L15D and L25D designs by LJM look very nice and I am leaning in that direction.
My problem concerns the power supply - I'd like to use a linear PS. I currently have a 40-0-40V 1kVA transformer and can get another one (the amps will be in separate enclosures), but this would result in rail voltages around +/-55V. The primary is spec'd at 115V, so I might get a tiny bit more voltage if the AC main is at 120V. But I am afraid it will still be below the minimum recommended rail voltages of +/- 60V for the L25D. I'd like to use it because it has two output devices.
Will these rail voltages cause UV protection to kick in (I believe that the L25D has that)?
Any other ideas that would allow me to use a 40-0-40 transformer with four L25D amps?
-Charlie
Thanks for the replies.
Confusion over what PS to buy, then some other stuff that came up at home put my whole audio project on hold for quite some time: So unfortunately the amps have sat in a box, all soldered up with nothing to play!
I will be looking at this again soon in order that I can get myself a nice hifi case and some power supplies ordered. Unfortunately the coffers are dry at the moment because I spent lots of money building a silent PC to deliver all my media (except for Vinyl). I'm very happy with it but itching to try out the two way speakers that I built for active drivers. I still even have the MDF and drivers to make matching subs in the garage....
Kind regards,
Jai
Confusion over what PS to buy, then some other stuff that came up at home put my whole audio project on hold for quite some time: So unfortunately the amps have sat in a box, all soldered up with nothing to play!
I will be looking at this again soon in order that I can get myself a nice hifi case and some power supplies ordered. Unfortunately the coffers are dry at the moment because I spent lots of money building a silent PC to deliver all my media (except for Vinyl). I'm very happy with it but itching to try out the two way speakers that I built for active drivers. I still even have the MDF and drivers to make matching subs in the garage....
Kind regards,
Jai
Well, to revive an old thread: I've just bought two SMPS800RE power supplies.
First step is to get one board working, power a sub and use my integrated to power a pair of standmounters.
Second step is to run two boards from one 800RE and one from the second. Powering the two stand-mounters and a sub.
Third step will be to run my DIY 2-ways with the sub. This requires four channels for the 2-ways and one for the sub.
I also have two car subs. An Infinity Kappa 12.1 in a small sealed enclosure (4ohm); and an Alpine 12" Dual 4ohm voice call affair. I'm tempted to have two sub channels...
All of this depends on finding a cheap case.
First step is to get one board working, power a sub and use my integrated to power a pair of standmounters.
Second step is to run two boards from one 800RE and one from the second. Powering the two stand-mounters and a sub.
Third step will be to run my DIY 2-ways with the sub. This requires four channels for the 2-ways and one for the sub.
I also have two car subs. An Infinity Kappa 12.1 in a small sealed enclosure (4ohm); and an Alpine 12" Dual 4ohm voice call affair. I'm tempted to have two sub channels...
All of this depends on finding a cheap case.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.