True, but it is on the bottom. When you show off your beautiful amp to your friends by removing the cover, they will never see it.
It is ironic. I ordered the wrong caps for C10 and got 33 pF SMD mica caps instead. No way to solder the little SMD caps to the TH, so I'm off to Mouser again. I wish these 33 pF SMD would help you, but they are the wrong value and I sense you are in a hurry.
Have fun.
Jac
Hurry but not so hurry as i discovered that my Lm318's that i already had and not ordered from Mouser is the TI version not National version so i will call tomorrow some stores to see if they stock the National version.
Also i wait for my Mlityc's Ag because i found it at a very good price 12,7EU/pc and ordered 4.
Also i wait for my Mlityc's Ag because i found it at a very good price 12,7EU/pc and ordered 4.
Power Supply Diodes
This only proves that I don't really pay attention to something until I try to build it.
Dario,
Please give me your thoughts. Why did you choose to use two AC inputs, each with their own diode bridge, but both feeding one pair of smoothing capacitors? What is the understood benefit of 2? Is there a load condition or frequency range that has a bigger advantage?
Thank you in advance. I'm sure this has been discussed before, but long before I arrived.
Jac
This only proves that I don't really pay attention to something until I try to build it.
Dario,
Please give me your thoughts. Why did you choose to use two AC inputs, each with their own diode bridge, but both feeding one pair of smoothing capacitors? What is the understood benefit of 2? Is there a load condition or frequency range that has a bigger advantage?
Thank you in advance. I'm sure this has been discussed before, but long before I arrived.
Jac
Does it matter that it is a TI version? I would have thought an lm318d is the same between National and TI.
Nice deal on the AGs.
Jac
I didn't any experiment, in this case I've simply used the most used topology in gainclones following Suburra's suggestion.
According Suburra the double rectifier gives a bigger soundstage and more refinement.
No, they're not the same.
Both works but Penasa optimized the compensation on the NS one and strongly suggests use of NS parts.
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
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
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 330°C) but applied tip for no more than 1-2 seconds so to not overheat them.
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.
the single bridge rectifier is according to reports the most commonly used. The dual bridge rectifier is relatively rarely used in comparison.
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.
Both are good options.
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.
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.
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
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
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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