I don't check, used series-connected SMPSUs from various vendors over quite a few years and never shorted one out from this 'problem'.
@pacificblue - which vendors' models have you found this V- to PE connection in?
Thump Lump.
You are getting conflicting advice here.
Be very careful in what you wire up and how you test your assembly.
I believe that some of our Members are quite deliberately giving out dangerous advice.
TREAD CAREFULLY.
You are getting conflicting advice here.
Be very careful in what you wire up and how you test your assembly.
I believe that some of our Members are quite deliberately giving out dangerous advice.
TREAD CAREFULLY.
This would be rather a serious matter if found to be true. Do you have any evidence as a foundation for your belief Andrew?
Andrew I suggested you read the data sheet and now you falsely accuse of some dangerous instruction. If you don't understand it, ask.
I don't think you were asking me to read a datasheet on an SMPS I don't have and will never have access to.
You are telling a Newbie to wire it up and only rarely will it bite if he follows your dangerous advice.
the evidence comes out of what you type.
Many and maybe even all metal chassis SMPS are Ground linked to PE.
I believe you are suggesting he experiment with Safety. You are behaving like a fool.
post3 thanks me for some information I passed on.
It does not ask or tell me to use or build or inspect that SMPS.
Thump Lump is the one that must check it.
You are telling him otherwise.
The evidence of what you type is that you're imagining things Andrew. This is not the first time this has happened.
Yes, and 'Ground' is?
Hilarious - because its totally unrelated to what I've written on this thread. Meanwhile, outside of Andrew's fertile imagination I said, in post #10 :
abraxalito said:
well I'm not telling him to check all the specs on the data sheet or anything else. You are the one insisting on what the OP MUST do. I'm just saying there is nothing unsafe or even damaging if he ignores your advise. again IT'S A NON-ISSUE
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SMPS and 3886
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Hifimediy
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http://www.diyaudio.com/forums/class-d/164274-new-tk2050-board-110.html#post2368920
I just measured my MeanWell S-350-36. There is no connection between N or L of the AC input and V+ or V- of the DC output. There appears to be a capacitive connection only between the ground terminal of the AC input and either of the DC outputs. The resistance starts at 1 meg and very slowly drifts down. I have 3886, bridged 3875 running with a true balanced source, and TK2050 amps (and many others) and the Tripath amps sound way better. A single 3886 never was very high up on my list in my system. They sound much, much, better running bridged but now your 4 ohm speaker may give them some trouble. A BPA200 set up would be my minimum recommendation for the 3886/ 3875 amps for decent sonics. I haven't tried my MeanWells bridged since I gave up on all of my class AB amps and the T amps only require a single sided supply. If you don't want to mod the Sure amps, the Hifimediy or Helder 2050 amps are ok right out of the box.
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Hifimediy
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http://www.diyaudio.com/forums/class-d/164274-new-tk2050-board-110.html#post2368920
Nothing changed. I mentioned it later but I did forget to say that in my OP. STEREO pair. Whether V- is tied to ground or not is a non-issue. If it is, simple mod. If not, no mod. So, back to original questions. I am understanding that it can be done with two of the fore mention SMPSU, that I can get 24V+/V0/24V-. The other question is if it will be enough power for a STEREO pair of LM3886 chip amps? Each SMPS is 350w.
does your two channel amp have 4 chipamps inside it?
Then peak current demand could be anywhere between 28Apk and 46Apk.
350 to 550W SMPS has no hope of meeting this potential transient demand.
Then peak current demand could be anywhere between 28Apk and 46Apk.
350 to 550W SMPS has no hope of meeting this potential transient demand.
demand
If you follow that logic, what size transformer would you recommend for a linear supply? 1000 to 2000va? Good luck buying anything like that for less than a king's ransom. Average consumption will be way less than 1 amp per chip playing music. 700 watts will power four channels very nicely.
4 chipamps each with a maximum output of 60W will work well from a 240VA to 480VA transformer. Much easier to get right than attempting to use SMPS that were almost certainly not intended to power an analogue power amp.
The 4chipamps will work with a transformer outside that recommended range.
The 4chipamps will work with a transformer outside that recommended range.
Andrews answer is an attempt as a 1st approximate and is too simplistic IMO, it's doubtful all 4 chip amps will be asking the same current levels since 1) they are bi-amped ie frequency band limited and 2) the gains will most likely be adjusted differently based on each drivers voltage sensitivity and target acoustic levels. ( not even mentioning the typical program material ) The long duration transients will be within the SMPS loops control and the fast transients will be supplied via the supply rail caps and external decoupling caps close to the chip. So the most likely scenario is the 4 ohm mid bass drivers require the most long term current demands ie within the SMPS current limit and will clip before the tweeters amps. Once the onset of clipping occurs either in the HF section or the mid bass then the system is maxed out so to speak and further supply current demand will be pointless.
This one to answer properly would require much more speaker design details and making some other assumptions and still be off without measuring some things more carefully. I think the risk is rather low on having the SMPS being the weak link in your system. IMO the weak link is assuming the mid bass chip amp itself will be able to supply the SQ one would expect for a good mid bass 4 ohm driver whose lowest impedance and sensitivity may be lower than you think.
This one to answer properly would require much more speaker design details and making some other assumptions and still be off without measuring some things more carefully. I think the risk is rather low on having the SMPS being the weak link in your system. IMO the weak link is assuming the mid bass chip amp itself will be able to supply the SQ one would expect for a good mid bass 4 ohm driver whose lowest impedance and sensitivity may be lower than you think.
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Nonsense, demanded by what? the 5" or 6" speakers, the chip amps themselves can only put out 5-6A or so. What happens to a much larger BJT >7A, these chip amps are much less than that. certainly not better than some good old fashioned pair of discretes in current ability.
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Where I am drawing a good bit of my info from about using SMPSs powering chipamps from is from here. SMPS for the Gainclone chip amp In use are four Skynet 8080 SMPSs. Two to get 6amp V+ and V- rails and two more to go from 12v to 24v. Used on a LM3875 stereo chipamp. It would seem that two Meanwell 24v 14.6a supplies (one for V+ and the other for V-) would be able to handle two stereo LM3886 chipamps. And reading further, the setup I mention above that NUUK is using for his LM3875 chipamp has been in use for quite awhile and is used as his preferred amp source.
I just don't like to use a single source for info, hence the start of this thread.
I just don't like to use a single source for info, hence the start of this thread.
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At the risk of ******* some people off, the bickering over the last few pages are a real turn-off. As I mentioned before, it's a non issue. I will check the Meanwell SMPSs first hand and if the connection is there, it's an easy mod. If not, then all is good. Either way, it's covered and a NON-ISSUE.
On to more important things. According to the page linked to in the previous post, a 6amps of SMPS is enough for a LM3875 stereo chip amp, at least for the author. The wattage output between a LM3875 and a LM3886 are very similar so the loads should be similar, so it would seem to me that 14.6amps should be enough for a pair of stereo LM3886 chip amps.
As far as having Enough power to cover transients and peaks, it would really depend on the music. I know all of you have seen just how compressed modern music is. Dynamics are a thing of the past. If I were to listen to older music (I do) and play it loud (I don't) then I can see a potential problem.
On to more important things. According to the page linked to in the previous post, a 6amps of SMPS is enough for a LM3875 stereo chip amp, at least for the author. The wattage output between a LM3875 and a LM3886 are very similar so the loads should be similar, so it would seem to me that 14.6amps should be enough for a pair of stereo LM3886 chip amps.
As far as having Enough power to cover transients and peaks, it would really depend on the music. I know all of you have seen just how compressed modern music is. Dynamics are a thing of the past. If I were to listen to older music (I do) and play it loud (I don't) then I can see a potential problem.
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