[amb]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif When I was building my M^3, I remember AMB being very adamant that even if they claim to be non-inductive, they always are........

The difference is that in an M³, we have opamps with bandwidth up in the MHz region. Inductance wreak havoc in a wideband feedback amplifier (so does capacitive coupling and leakage). In fact you can't get rid of inductance entirely, even a short piece of wire has some. This is why careful layout and proper parts selection is important in such an amp, in order to minimize undesirable inductive/capacitive effects.

I received a report from someone who built a Mini³ and was experiencing oscillations. It turns out he ignored the instructions and used larger "boutique" resistors on the board, mounted vertically tombstone-style. Yes, just a few extra millimeters of resistor leads here and there (with the associated additional inductance) was enough to upset the circuit. The builder swapped back to the default miniature resistors and the problem was fixed.

In the starving student amp, however, the bandwidth is nowhere nearly as wide and the circuit is non-feedback, so some resistor or wire inductance is probably inconsequential.

 

[Beefy]

Quote:

Originally Posted by Jelle Schrijver /img/forum/go_quote.gif It's nice to see that you are so open minded....

Look buddy, I'm a postdoc research scientist. If a person makes such outlandish claims like undetectable vibrations causing capacitance changes and generate a signal, it is their burden of proof to provide something scientific that supports it.

Quote:

One last advice: Look up respect in the dictionary

My respect is reserved for those who earn it. Charlatans who use emotive/social arguments to try and sell highly questionable products don't nearly come close.

 

[Beefy]

Quote:

Originally Posted by amb /img/forum/go_quote.gif The difference is that in an M³, we have opamps with bandwidth up in the MHz region.

Oh, absolutely...... I'm not questioning you at all - just using your info as a reference

 

[Solan]

Inductance is the magnetic effect moving electrons have on one another, so if your electrons are moving, you have inductance.

We wind coils when we want to maximize this effect, but make our wires as short and straight as possible when we want to minimize it. Why? Because the effect depends on length of wire.

Which frequency you get from a coil does of course depend on the rest of the circuit, i.e. on its interaction with the capacitors. In a simple closed circuit, it's proportional to the square root of (inductance divided by capacitance).

 

[gurusan]

ignore

 

[digger945]

Quote:

Originally Posted by SiBurning /img/forum/go_quote.gif Now before you decide to omit those capacitors, read the second paragraph of post 18 from this head-fi thread: http://www.head-fi.org/forums/f6/byp...81/index2.html

You are speaking to the use of these caps with OPAMPs only, right?
Not any problems if used in a PS, bypassing the rectifier diodes, right?

 

[qusp]

has anyone got an updated email for michael percy? i've just tried to make an order but my email bounced back. his prices are quite good so would prefer to get from him.

thanks in advance

 

[digger945]

Maybe with the upcoming miniMAX builds, he is swamped with orders. I have read a lot of HFers here who are also ordering parts from him, me too.

 

[Pars]

Quote:

Originally Posted by digger945 /img/forum/go_quote.gif You are speaking to the use of these caps with OPAMPs only, right? Not any problems if used in a PS, bypassing the rectifier diodes, right?

The caps across rectifier diodes are normally called snubbers, and are there to try to remove the spikes that occur with the switching on/off the diodes do to rectify. This is why many will use Schottky diodes as they do not spike, but these can be hard to find in suitable ratings, particularly for power amps, etc. 31DQ10 is one I use sometimes. The HexFred and other soft recovery diodes reduce this alot, but do not completely eliminate it. For a good read on snubbers: http://www.hagtech.com/pdf/snubber.pdf

 

[digger945]

Thanks Pars, the reason I asked was for a Dynahi PS with MUR860's bypassed with a Kemet 100pF Ceramic. This is on Ti Kan's recommendation from a thread here somewhere.
Thanks again.

 

[luvdunhill]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif The caps across rectifier diodes are normally called snubbers, and are there to try to remove the spikes that occur with the switching on/off the diodes do to rectify. This is why many will use Schottky diodes as they do not spike, but these can be hard to find in suitable ratings, particularly for power amps, etc. 31DQ10 is one I use sometimes. The HexFred and other soft recovery diodes reduce this alot, but do not completely eliminate it. For a good read on snubbers: http://www.hagtech.com/pdf/snubber.pdf

I noticed yesterday that there is a 1.2kV PIV Schottky diode for sale at Digikey. Pretty insane...

 

[Uncle Erik]

Quote:

Originally Posted by qusp /img/forum/go_quote.gif has anyone got an updated email for michael percy? i've just tried to make an order but my email bounced back. his prices are quite good so would prefer to get from him. thanks in advance

Try again and keep after him. I usually include "second (third, etc.) attempt to order" in the title of my emails. It eventually gets through.

Once he issues an invoice, he always ships fast and the orders are accurate. I really wish he had a site set up with a cart, etc., so you could order online. However, he has great stuff, fair prices and the orders are accurate. I think it's worth doing business with him.

 

[-=Germania=-]

I recently tried out Percy audio mainly to get some more sleeving and heat shrink stuffs. It does take a while....so be prepared....

 

[luvdunhill]

meh, I get same week service from Percy... e-mail on Monday, parts on Friday.

 

[qusp]

well I haven't got a reply yet, but the email I sent yesterday to a new email address didn't bounce back like the link from his catalogue which has obviously been shut down, so I assume it got through. Can anyone confirm that michael@percyaudio.com is the right account I found it after googling his name. I don't mind waiting a little because its a decent size order so I save a bit. BTW has anyone tried the XLO minis that he has in stock there? also considering getting the eichmann chassis mounted RCA to go with my silver bullets, anyone use them? i've only used the bullet plugs i'm looking to get a female connector that matches the silver bullet in quality. this will be my first attempt at building a case; plenty of experience with making cables and modding ipods etc. but never made an amp or in this case a VCAP dock, also making the bantam dac and going a little BG crazy in it.