SMSL SA-60: battery vs. switcher
Meanwell NES-24-150 power supply vs. 12 volt battery
Meanwell set to its lowest adjustable output voltage, measured at 22.2 volts.
Fully charged 12 volt SLA battery, 7.5Ah
Pluses and minuses.
The higher voltage of the Meanwell (22.2 v) allows the sound to open up and become more dynamic and rythmic.
On the other hand, the pure DC voltage of the battery provides a slightly smoother, more musical sound, a little less edgy. The differnce would probably not be noticeable without direct comparison.
Despite its non-audiophile heritage, the Meanwell sounds good with this amp. For convenience of not having to worry about recharging and maintaining a battery, the Meanwell wins out.
But how to get both qualities? A higher voltage battery? 24 volt is too high a voltage for optimum sound, per other reports. I don't see a battery in the 21 volt range. Appears not advisable to place unmatched batteries (like a 9v and 12v) in series.
Pure analog supply at 21 v? Looking into this option.
Meanwell NES-24-150 power supply vs. 12 volt battery
Meanwell set to its lowest adjustable output voltage, measured at 22.2 volts.
Fully charged 12 volt SLA battery, 7.5Ah
Pluses and minuses.
The higher voltage of the Meanwell (22.2 v) allows the sound to open up and become more dynamic and rythmic.
On the other hand, the pure DC voltage of the battery provides a slightly smoother, more musical sound, a little less edgy. The differnce would probably not be noticeable without direct comparison.
Despite its non-audiophile heritage, the Meanwell sounds good with this amp. For convenience of not having to worry about recharging and maintaining a battery, the Meanwell wins out.
But how to get both qualities? A higher voltage battery? 24 volt is too high a voltage for optimum sound, per other reports. I don't see a battery in the 21 volt range. Appears not advisable to place unmatched batteries (like a 9v and 12v) in series.
Pure analog supply at 21 v? Looking into this option.
three charged 6V batteries give supply between 19V and 20V.
that's what i originally bought for a portable system.
but i'm using it at home, too, because it is so good (ahhh-yeah)
that's what i originally bought for a portable system.
but i'm using it at home, too, because it is so good (ahhh-yeah)
***
Great idea, thanks.
Do you constantly trickle charge the batteries? Or how do you handle the charging issue? What Ah batteries do you have?
they are rated for 7ah.
they discharge very slow with those class d amps.
i never had them at the absolute minimum - not even lower than 6V.
even after long long sessions outdoors with volumes that would kill my ears indoors they are not completely discharged.
i know i should charge them more often than i actually do.
but they work great for more than a year now with sporadic charging.
for 10€ each a really good investment imo.
they discharge very slow with those class d amps.
i never had them at the absolute minimum - not even lower than 6V.
even after long long sessions outdoors with volumes that would kill my ears indoors they are not completely discharged.
i know i should charge them more often than i actually do.
but they work great for more than a year now with sporadic charging.
for 10€ each a really good investment imo.
they are rated for 7ah.
they discharge very slow with those class d amps.
i never had them at the absolute minimum - not even lower than 6V.
even after long long sessions outdoors with volumes that would kill my ears indoors they are not completely discharged.
i know i should charge them more often than i actually do.
but they work great for more than a year now with sporadic charging.
for 10€ each a really good investment imo.
they discharge very slow with those class d amps.
i never had them at the absolute minimum - not even lower than 6V.
even after long long sessions outdoors with volumes that would kill my ears indoors they are not completely discharged.
i know i should charge them more often than i actually do.
but they work great for more than a year now with sporadic charging.
for 10€ each a really good investment imo.
Thanks for the info, Buehgemeiste.
I'll get some 6v SLA's and give them a try.
I do like the sound of the pure DC from the 12v battery even though the voltage is lower than optimum. No ripple, no AC, just purity. Like melted water off a glacier.
I'll get some 6v SLA's and give them a try.
I do like the sound of the pure DC from the 12v battery even though the voltage is lower than optimum. No ripple, no AC, just purity. Like melted water off a glacier.
I have a switching power supply coming my way that is 24V at 8A. But I had them debug it so the ripple/noise is 76mv.
This is likely because of the battery's inherent isolation and not being a source of switching noise.
Addressing the noise issues of the SMPSU. Either a common-mode choke (input or output side of the Meanwell works well) or input transformers to the amp, or both.
***
Thanks, I'll look into this further. Do you have a suggested choke or input transformer?
I suggest winding your own as then they'll be optimized for the particular application. In the realm of chokes, multi-segmented ones work best but I've yet to find any commercial source. For input trafos, I've wound them using ferrite cores and these are more than an order of magnitude cheaper than nickel-cored ones.
In case anyone is looking for a cheap enclosure: the Danzz version fits perfectly in a 125B style enclosure ($4.99 at Tayda). I'm going to try fitting a speakon socket in there and use it as a bass guitar amp.
Attachments
that´s awesome!!
i like tayda.
they have good prices and deliver incredibly fast.
my last two orders took only one week from thailand to germany.
please post a pic when have managed the sockets.
i imagine that wiring is not easy in that little space.
would those inductors fit on the danzz-board?
http://www.produktinfo.conrad.com/d...-WE_PD_SMD_SPEICHERDROSSEL_74477091_de_en.pdf
Nice tip on the Hammond 125B box. Look at all the colors they come in.
http://www.mammothelectronics.com/4S125B-p/500-1002.htm
http://www.mammothelectronics.com/4S125B-p/500-1002.htm
This one from Parts Express for $10 works good for the Blue/Black board if your
adding a pot/knob, and switch.
Aluminum Amplifier Case 1.93" H x 2.94" W x 4.72" D
The Meanwell NES-150-24 SMPS measured below 1 mv AC voltage on my Fluke 87 V meter both with no audio input to the amp and while running music through the amp at high levels. Perhaps the meter is understating the noise because it's intermittent or at a higher frequency, but even in peak hold mode the meter doesn't get above 1 mv.
So the Meanwell appears pretty clean. I also installed a ferrite core in the DC cable to the amp with about 8 turns of wire on it.
So the Meanwell appears pretty clean. I also installed a ferrite core in the DC cable to the amp with about 8 turns of wire on it.
Fluke 87:
AC bandwidth 20 kHz with low pass filter; 3 db @ 1 kHz
Fluke 87V Industrial Multimeter
So the meter will show a little more than you can hear.
That means the audio is not getting to the supply.
🙂
AC bandwidth 20 kHz with low pass filter; 3 db @ 1 kHz
Fluke 87V Industrial Multimeter
So the meter will show a little more than you can hear.
That means the audio is not getting to the supply.
🙂
Did you do the same for your 12V SLA? I think my smps is better than my linear, maybe because linear isn't blocking 3116 enough. It isn't just PSU that switches, amp too.
The 3116 met its match: the B&W Nautilus 805.
This speaker presents a difficult load for amplifiers. The speaker is also extremely revealing and lays bare the slightest deficiency in any upstream components. The speaker is in the "unforgiving" school, so that it takes a lot of work to get this speaker to sound good (unlike many inexpensive speakers which are "forgiving" and tend to romanticize and make anything sound good).
Even with 22 volts and 150 watts of DC input power available, the SA-60 had trouble driving the 805's. This was a stereo pair of 805's, and the amp was driving them in stereo mode. Dynamics were squashed even at moderate levels, with the speakers sounding flat and reticent, and increasing distortion levels audible on peaks.
So this amp by itself is not up to driving the 805's. Note, however, the same can be said of many amps, including some expensive ones, which have sounded worse than the 3116 based amp.
My plan is to get a pair of amps and drive the speakers in bi-amped mode, so that each amp is driving only one speaker, and each channel is driving only one driver. The B&W's like being bi-amped, and it also makes them an easier load for the amp. The SA-60 will likely do much better in this mode, and we'll see how it compares to other amps.
If that's still not enough, then the next option would be to use 4 of the amplifiers in PBTL mode, with each mono-mode amp driving a single driver. That should resolve the power deficiency issues. These amps are so inexpensive that the cost of 4 amplifiers is still way below the cost of most stereo or monoblock amps that I'd use with the speakers.
This speaker presents a difficult load for amplifiers. The speaker is also extremely revealing and lays bare the slightest deficiency in any upstream components. The speaker is in the "unforgiving" school, so that it takes a lot of work to get this speaker to sound good (unlike many inexpensive speakers which are "forgiving" and tend to romanticize and make anything sound good).
Even with 22 volts and 150 watts of DC input power available, the SA-60 had trouble driving the 805's. This was a stereo pair of 805's, and the amp was driving them in stereo mode. Dynamics were squashed even at moderate levels, with the speakers sounding flat and reticent, and increasing distortion levels audible on peaks.
So this amp by itself is not up to driving the 805's. Note, however, the same can be said of many amps, including some expensive ones, which have sounded worse than the 3116 based amp.
My plan is to get a pair of amps and drive the speakers in bi-amped mode, so that each amp is driving only one speaker, and each channel is driving only one driver. The B&W's like being bi-amped, and it also makes them an easier load for the amp. The SA-60 will likely do much better in this mode, and we'll see how it compares to other amps.
If that's still not enough, then the next option would be to use 4 of the amplifiers in PBTL mode, with each mono-mode amp driving a single driver. That should resolve the power deficiency issues. These amps are so inexpensive that the cost of 4 amplifiers is still way below the cost of most stereo or monoblock amps that I'd use with the speakers.
***
I didn't measure the 12v SLA battery input power. I assumed it would be pure DC with no AC noise at all. I was surprised how low the Meanwell SMPS AC noise is, yet I think the battery still sounds cleaner than the SMPS.
I've ordered three 6 volt SLA's, and will wire them in series to see how the amp responds to that higher voltage power source. Obviously keeping 3 batteries charged is not the lowest-maintenance approach to powering this amp - I don't readily find any 18 volt charger for sale, and having to charge each battery individually at 6v is a pain.