I measured the impedance of the L||R network I use using an HP 4194A impedance analyzer. I used the analyzer to extract the L and R of the network. The measured L and R were within expected component tolerances of the design target values.
In the design documentation I specify the exact same resistor that I used for the impedance measurement. If you follow the design documentation, you'll be successful. If you colour outside the lines a bit, you will likely be successful as well. After all, the practice of putting the resistor inside the inductor has been used for decades with good results.
The performance measurements shown on my website were performed with the board as built according to the Mouser BOM and design documentation.
I do understand your concern. I have seen circuits where the output inductor was wound around a DC coupling capacitor (aluminum can electrolytic). While I don't have data to back up my concern, that approach did not sit well with me. In my case, however, there is very little metal inside the inductor and the amount that's there has been characterized during the design phase of the project.
Tom
In the design documentation I specify the exact same resistor that I used for the impedance measurement. If you follow the design documentation, you'll be successful. If you colour outside the lines a bit, you will likely be successful as well. After all, the practice of putting the resistor inside the inductor has been used for decades with good results.
The performance measurements shown on my website were performed with the board as built according to the Mouser BOM and design documentation.
I do understand your concern. I have seen circuits where the output inductor was wound around a DC coupling capacitor (aluminum can electrolytic). While I don't have data to back up my concern, that approach did not sit well with me. In my case, however, there is very little metal inside the inductor and the amount that's there has been characterized during the design phase of the project.
Tom
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The board order is now marked "ready to ship" by the manufacturer, so I expect the boards to arrive this coming week. I'll ship them as soon as they get in.
Of the few extra boards I ordered, I have 12 left.
Tom
Of the few extra boards I ordered, I have 12 left.
Tom
The boards arrived a few days early and the manufacturer included one more board than I ordered (nice folks!). For those who have ordered already: Your boards will be in the mail by tomorrow morning. Regular airmail will arrive in 2-3 weeks (1-2 weeks to the US). Tracked mail tends to be a bit faster.
I have 13 boards left.
Tom
I have 13 boards left.
Tom
Good to hear.
I have seven boards left. The LM4780 is playing hard to get, so with the help of a forum member I have a stick of them on the way from RS Components in the UK. I expect to have them here in about two weeks and will ship the remaining boards when they arrive.
Tom
I have seven boards left. The LM4780 is playing hard to get, so with the help of a forum member I have a stick of them on the way from RS Components in the UK. I expect to have them here in about two weeks and will ship the remaining boards when they arrive.
Tom
I ended up buying the metal canned versions, they look like something from war of the worlds sat up above the pcb on spindly legs.
Hi Tom,
Ill have 2 x pcbs and LM4780 chips as well.
do you want to send me a Paypal invoice?
Brad
Ill have 2 x pcbs and LM4780 chips as well.
do you want to send me a Paypal invoice?
Brad
Haha,
I've already had quite a few of these boards. Last project was for a 10ch amplifier with 6 Neurochrome modules for my LX521s
I've already had quite a few of these boards. Last project was for a 10ch amplifier with 6 Neurochrome modules for my LX521s
Builder Brad,
Smart move! Have you got the LX521 up and running?
I have a stereo Mod-86 and really like it - so any comments I make about the amp are likely to be biased. 😀
Smart move! Have you got the LX521 up and running?
I have a stereo Mod-86 and really like it - so any comments I make about the amp are likely to be biased. 😀
I've had the LX521s running for quite a while now, originally built AKSA amplifiers for them. The new amp has 2 x mod-86s 4 x Par-86s and 4 x UCD400s for the LX521s.
Using the Minidsp 2x8 at the moment, but have been working on a Minisharc based dsp and 4 x Buffalo III Dacs, which have perfect differential output for Toms amplifiers and the Hypex UCD modules.
Using the Minidsp 2x8 at the moment, but have been working on a Minisharc based dsp and 4 x Buffalo III Dacs, which have perfect differential output for Toms amplifiers and the Hypex UCD modules.
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