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Old 14th August 2009, 06:49 PM   #1
PJPro is offline PJPro  England
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Default First LM3886.........

I mentioned in my other thread that I wanted to pull together all the bits and pieces to summarise the way forward. I also thought it would help me understand how I was going to wired all the components together. The picture is below.

Click the image to open in full size.

What do you think? Does it look alright? Grateful for any comments.

I've asked on the ESP Forum how I can power my loudspeaker protection circuit (ESP P39) from my soft start circuit (ESP P33). The secure notes makes reference to doing this but doesn't provide any detail.

Oh.....and it seems the loudspeaker protection circuit will operate with just a single output.

I am now in possession of all the boards for the P33, P39 and E24 so am in the process of identifying and ordering parts.
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Old 15th August 2009, 07:39 AM   #2
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So, I'll assume all looks well then.
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Old 15th August 2009, 12:14 PM   #3
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Don't assume This is upgrade ilsand after all, probably a lot less traffic than usual, and the people who would normally comment may not even be watching. I had a look at the block diagram, but I'm afraid I didn't understand it (probably largely due to not knowing what all of the blocks are).

I've never had anything more complex than a mains switch a fuse and a terminal block....

Tony.
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Old 15th August 2009, 01:06 PM   #4
Stuey is offline Stuey  Australia
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Hello Tony!

I'd been wondering about where you got to! Great photos.

BTW I've given up on Aussiefrogs; just got sick of it, really. This is my main haunt online now, I guess.

Good to see you're not ill or something.

Stuey
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Old 15th August 2009, 06:51 PM   #5
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The diconnection network can not only lift the input ground from the chassis. You can also use it to separate that clean input ground from the dirty power and speaker ground, if you connect amplifier power ground and speaker ground directly to the case. For your first tests you should leave the wires long enough to try both configurations.

If you put the RF filter for the speaker output directly behind the amplifier, you also have protection, when the relay is off.

You may need a second RF filter at the amplifier input or move the existing RF filter as close to the amplifier input pins as possible. That way it filters out any disturbances that still enter the wires and traces on the way from the RCA connector to the IC.

Heatsink in the center? Well, if you have enough holes in the case below and above it, and enough distance to the supply capacitors.

Can't you feed the soft start relays from the same transformer as the switch circuit? The soft-start relay should not draw 5 VA and the relay before it has the same function as the one that activates the 5 VA transformer, so you might as well skip it.

Is that drawing on scale?
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Old 15th August 2009, 10:40 PM   #6
PJPro is offline PJPro  England
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Quote:
Originally posted by pacificblue
The diconnection network can not only lift the input ground from the chassis. You can also use it to separate that clean input ground from the dirty power and speaker ground, if you connect amplifier power ground and speaker ground directly to the case. For your first tests you should leave the wires long enough to try both configurations.
OK. That's a cool idea. I'm liking this disconnecting network more and more.

Quote:
Originally posted by pacificblue

If you put the RF filter for the speaker output directly behind the amplifier, you also have protection, when the relay is off.
Am I worried about RF when the speakers are off? But yes. I can place the filtering either side of the relay.

Quote:
Originally posted by pacificblue

You may need a second RF filter at the amplifier input or move the existing RF filter as close to the amplifier input pins as possible. That way it filters out any disturbances that still enter the wires and traces on the way from the RCA connector to the IC.
OK. Yes.

Quote:
Originally posted by pacificblue

Heatsink in the center? Well, if you have enough holes in the case below and above it, and enough distance to the supply capacitors.
Well, I thought it might shield the amp from the PSU a little and keep the amp as close to the inputs/outputs as possible.

Quote:
Originally posted by pacificblue

Can't you feed the soft start relays from the same transformer as the switch circuit? The soft-start relay should not draw 5 VA and the relay before it has the same function as the one that activates the 5 VA transformer, so you might as well skip it.
Well, the ESP instructions require a 5VA transformer delivering 9VAC. The switch circuit delivers 12VAC from 1.5VA.

Quote:
Originally posted by pacificblue

Is that drawing on scale?
No. It's my mockup to attempt to understand where everything was going and how it was going to be wired up.

Thanks for the advice pacificblue. Very much appreciated.
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Old 16th August 2009, 01:40 AM   #7
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Hi Stuey, I've sent you an email. (it will come through with my email address, but don't feel obligated to reply if you don't want to give me your email address .

Back on topic PJPro, does the ESP article say you need the 5VA 9V for safety (or technical) reasons? Since you have a number of different modules it may be the case you can piggyback some stuff, I'm guessing that the reason is it assumes your main transformer will be providing say 25V (and may not be clean due to modulation from the main amp), so specifies a separate transformer. Rod could probably best answer the question of whether you can use your other transformer. The less transformers you have the better!!! I'm not feeling like reading all of the articles for the various projects I'f you are worried about the voltage you could just put in a voltage regulator to bring it down to whatever voltage (I'm assuming it ends up as DC) the 9V transformer ends up delivering.

I took a rather different approach to my LM3886 project I did a P2P. The thread of my (well most of it) journey is here --> Wintermute's Gainclone there were a few other threads where I asked specific questions before and after starting the build but that pretty much documents the build process.

cheers,

Tony.
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Old 16th August 2009, 06:39 AM   #8
Stuey is offline Stuey  Australia
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Cheers Tony.

PJ, here's a pretty good PDF about ground loops etc. if you have the time to read it!

http://www.jensen-transformers.com/a...%20seminar.pdf

Cheers

Stuey
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Old 16th August 2009, 06:52 AM   #9
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Quote:
Originally posted by PJPro
Am I worried about RF when the speakers are off?
Not you, but maybe the amplifier.
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Old 16th August 2009, 08:28 AM   #10
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Quote:
Originally posted by wintermute
PJPro, does the ESP article say you need the 5VA 9V for safety (or technical) reasons? Since you have a number of different modules it may be the case you can piggyback some stuff, I'm guessing that the reason is it assumes your main transformer will be providing say 25V (and may not be clean due to modulation from the main amp), so specifies a separate transformer.
It's safety. If you attach the soft start circuit to the main 25VDC transformer, you can arrive at a situation where the main fuse does not blow. Rod strongly recommends an auxillary transformer.

Quote:
Originally posted by wintermute
The thread of my (well most of it) journey is here --> Wintermute's Gainclone there were a few other threads where I asked specific questions before and after starting the build but that pretty much documents the build process.
Thanks, I'll take a read.
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