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Old 14th August 2012, 12:21 AM   #111
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Default ERO KP 1834 soldering

Dario,

You had suggested that we leave the KP1834 caps to solder last, to avoid extra heat. If I wait until last, then the caps are surrounded by other parts and it may be difficult to heatsink them on the top of the board. Did you solder them in last and did you use heatsinks?

Also, I'm surprised that you soldered in C1 and C2 before the LM317s, MP915s, and the power supply diodes. R3 as well. C1 and C2 are taller. Is there a reason to solder C1 and C2 first?

Thanks in advance.

Jac
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Old 14th August 2012, 01:12 AM   #112
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Originally Posted by lehmanhill View Post
If I wait until last, then the caps are surrounded by other parts and it may be difficult to heatsink them on the top of the board. Did you solder them in last and did you use heatsinks?
I can't see how you can heatsink them if you mount them correctly (you would leave some lead exposed on the upper side to heatsink... no good IMHO)...

I didn't use any heatsink on them.

Simply, as suggested also by AndrewT, I've used a pretty high temperature (say 330C) but applied tip for no more than 1-2 seconds so to not overheat them.

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Originally Posted by lehmanhill View Post
Also, I'm surprised that you soldered in C1 and C2 before the LM317s, MP915s, and the power supply diodes. R3 as well. C1 and C2 are taller. Is there a reason to solder C1 and C2 first?
Yes, probably C1 and C2 should have been mounted after all positions you mentioned.

When I've mounted C1 and C2 I was a bit tired and inverted order.

Nevertheless I've had no problems with the order depicted on the tutorial.
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Old 14th August 2012, 10:55 AM   #113
AndrewT is offline AndrewT  Scotland
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............... I've simply used the most used topology in gainclones .
the single bridge rectifier is according to reports the most commonly used. The dual bridge rectifier is relatively rarely used in comparison.
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Old 14th August 2012, 04:53 PM   #114
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Where should be connected HSGND and PGND? Should connect PGND to chassis ?
My RCA-in connectors are isolated from chassis.

For connection between RCA socket and the pcb connector would be good a shielded coax cable or simply twisted cables ?

Last edited by atupi; 14th August 2012 at 05:17 PM.
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Old 14th August 2012, 05:27 PM   #115
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Where should be connected HSGND and PGND? Should connect PGND to chassis ?
It depends on what grounding scheme you want to implement.

HSGND should be connected to a heatsink but only if it's insulated from chassis.

PGND can be connected to chassis (and thus safety-earth) or not.

I prefer (soundwise) PGND not connected.

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Originally Posted by atupi View Post
For connection between RCA socket and the pcb connector would be good a shielded coax cable or simply twisted cables ?
Both are good options.
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Old 14th August 2012, 05:40 PM   #116
AndrewT is offline AndrewT  Scotland
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I find that twisted pair are good enough. But then the only RF transmitter I have in my home is one mobile phone.

I can't hear interference from mobile to amp in any of the amps I have built even though they are all extensively tested when completely without any screening case/chassis.
Whereas a table alarm clock goes scatty when I turn off my mobile before I go to sleep. Same for a computer speakers that happen to be powered up.
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Old 14th August 2012, 06:05 PM   #117
atupi is offline atupi  Romania
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To me is a bit strange to have that nice metal enclosure and not to benefit of a goos shielding. A will test to see how it sounds with PGNG connected to the enclosure.
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Old 14th August 2012, 10:01 PM   #118
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Quote:
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the single bridge rectifier is according to reports the most commonly used. The dual bridge rectifier is relatively rarely used in comparison.
Hi Andrew,

Like you, I have seen a lot of single bridge amps in the gainclone and MyRef designs.

Here is my theory on why a two diode bridge might sound better. I would love feedback from all.

Simply, when two bridges are used, the current through each bridge is half of a single bridge for a given load. I have read that the diode switching noise is a function of current, so lower current per diode means lower power supply noise. I am assuming that the noise spikes from the two bridges don't add up to a high amplitude.

I think this also means that the advantage of two bridges will depend on how much load the amp is driving. For example, a full range speaker with medium efficiency, may be using a lot of current and gain a big advantage from the two bridges. An amp used only to drive a high efficiency, high impedance tweeter is likely to use much less current and have less benefit from two bridges.

Any thoughts?

Jac
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Old 14th August 2012, 10:04 PM   #119
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Default Andrew's Vacation - Off Topic

We heard you were off on vacation. I wondered where someone from Scotland would go on vacation? Your country is so beautiful, I would think most other places would be a disappointment.

Jac
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Old 14th August 2012, 11:31 PM   #120
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Default C14 Question

Dario,

I just found something interesting. The caps I ordered from Mouser for C14 turned out to be 35 V. The BOM says they should be 50 V. When I put the part number from the BOM into the Mouser website, it comes up as a 35 V cap. As this is a speaker protection cap and is working against 24V, my guess is that the 35 V cap will work OK.

Just checking, are these OK at 35 volts?

Jac
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