I'm not doubting you. I was just interested in the reasoning behind using said part. I'll be using a CL-60 then. Thanks as always.
Hey, I've actually got mostly everything complete now, and it's pretty much just wiring now.
I've added a few more boards you see...not just the LM3886 board. I now have another LM4780 board + a preamp board + some speaker protect boards + 2 small power supplies to run the other boards....
CL-60 is rated at 5A. What does this 5A mean? Will it be enough? I've calculated max power draw EVER to be around 9A or so. And that's seriously maxing out...
I've added a few more boards you see...not just the LM3886 board. I now have another LM4780 board + a preamp board + some speaker protect boards + 2 small power supplies to run the other boards....
CL-60 is rated at 5A. What does this 5A mean? Will it be enough? I've calculated max power draw EVER to be around 9A or so. And that's seriously maxing out...
9A max implies that your transformer is passing on a maximum of about 900W.
Either you have a transformer that is too big for powering chipamps or you have sufficient short term current capacity to drive an accidental short circuit at the speaker terminals.
Either you have a transformer that is too big for powering chipamps or you have sufficient short term current capacity to drive an accidental short circuit at the speaker terminals.
Okay 9A is a lie....
I don't understand transformer ratings. It's a 250VA 25V transformer. 2x LM3886 + 1x LM4780 is what is inside. I don't know how to really calculate it. =/
But since the CL-60 is inline with the protective ground, does it really need a very high rating?
I don't understand transformer ratings. It's a 250VA 25V transformer. 2x LM3886 + 1x LM4780 is what is inside. I don't know how to really calculate it. =/
But since the CL-60 is inline with the protective ground, does it really need a very high rating?
I haven't done anything yet....
I'm just going off what was reccomended before. This is the old diagram from the other page.
I'm just going off what was reccomended before. This is the old diagram from the other page.
The CL60 has nothing to do with required transformer rating.
VA is similar to power, except it takes into account that many loads do not have perfect power factors. You have 4 channels each capable of delivering ~5A on ~35V rails. Multiply volts x amps, you are looking at 175 VA peak per channel, or 700 VA peak total.
Here's where a bit of engineering/cost tradeoff comes in. Realistically, with music your peak to average ratio is at least two, so your average draw will likely be less than 350 VA. However, you don't want to run a transformer at its rating or it will get quite hot and shorten its life as well as surrounding parts. Remember also that capacitive input filters draw more average current than is delivered to the amp. For continuous high power duty, consider 800VA or better.
You are using this amp at home so you are unlikely to run anywhere near maximum power for any length of time. Subwoofer duty may be different, but you can generally use a much smaller transformer with a class AB amp, such as your chip amps. Some musical instrument amp makers intentionally undersize the transformer to provide some circuit protection, but you don't want to go there.
A rule of thumb for AB amps would be select a transformer rated at twice the rated output power. Since you have 4 60W channels, two 250 VA transformers are indicated. You may be able to use the one, but it will likely limit your output and you may notice some distortion on loud passages. It all depends on how efficient your speakers are and how loud you like to listen.
VA is similar to power, except it takes into account that many loads do not have perfect power factors. You have 4 channels each capable of delivering ~5A on ~35V rails. Multiply volts x amps, you are looking at 175 VA peak per channel, or 700 VA peak total.
Here's where a bit of engineering/cost tradeoff comes in. Realistically, with music your peak to average ratio is at least two, so your average draw will likely be less than 350 VA. However, you don't want to run a transformer at its rating or it will get quite hot and shorten its life as well as surrounding parts. Remember also that capacitive input filters draw more average current than is delivered to the amp. For continuous high power duty, consider 800VA or better.
You are using this amp at home so you are unlikely to run anywhere near maximum power for any length of time. Subwoofer duty may be different, but you can generally use a much smaller transformer with a class AB amp, such as your chip amps. Some musical instrument amp makers intentionally undersize the transformer to provide some circuit protection, but you don't want to go there.
A rule of thumb for AB amps would be select a transformer rated at twice the rated output power. Since you have 4 60W channels, two 250 VA transformers are indicated. You may be able to use the one, but it will likely limit your output and you may notice some distortion on loud passages. It all depends on how efficient your speakers are and how loud you like to listen.
The IEC green or green/yellow must be permanently connected direct to chassis. Nothing else needs to be connected here. This is the primary Protective Earth (PE). Never tamper with it. Never add or subtract anything from it. It is PERMANENT and must be mechanically secured.
The Main Audio Ground (Star Ground) can be anywhere between chassis and the other components that need to be Chassis Grounded. Do not use the PE connection.
The Main Audio Ground (Star Ground) can be anywhere between chassis and the other components that need to be Chassis Grounded. Do not use the PE connection.
For my DC input jack, with +, -, gnd, gnd needs to be permanently secured to chassis. All other grounds gets soldered to -? Am I interpreting this correctly?, just a newbie...
Hi,
the DC input jack comes from a source.
Is that source equipment to ClassI or ClassII standard?
If you don't know that you need this information then you are a danger to yourself and anyone else who touches your mains DIY builds.
Read more about mains voltage Safety & mains equipment Safety.
the DC input jack comes from a source.
Is that source equipment to ClassI or ClassII standard?
If you don't know that you need this information then you are a danger to yourself and anyone else who touches your mains DIY builds.
Read more about mains voltage Safety & mains equipment Safety.
Wrong, I am talking to you, Post49.
The proposal you show is unsafe.
That's why your earlier statement concerned me and why I asked you to show what you were doing.
Whereas post51 is addressed to G.
The proposal you show is unsafe.
That's why your earlier statement concerned me and why I asked you to show what you were doing.
Whereas post51 is addressed to G.
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sorry, my mistake, DC input is from the wallwart power supply in my case, don't know Class I or II.
Sorry?
The Chassis is wooden. How do I connect an electrical connection to wood?
Bob Ellis said that it was a good setup. All I'm doing is connecting the ground plane of the two boards to protective earth...which is correct.
Then go and find out.
If the DC supply meets double insulated standard, i.e. ClassII, then the receiver does not need to be Safety Earthed.
Connect the PE to the largest most exposed piece of metalwork, permanently.
Then connect all other exposed conductive parts to that same piece of Protected metalwork.
Consider connecting all other large pieces of internal conductive parts to the Protected metalwork.
What Andrew is saying is that since your heat sinks are the largest exposed pieces, connect them directly to the IEC - that makes them the "protected metalwork". The CL60 from the star ground should connect to one of the heat sinks rather than the IEC.
My heatsinks aren't going to be exposed, so I don't think I'm even going to hook them up to PE. Can I just ignore the two black lines coming from the heatsink and just use CL- 60 with the star ground.
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