does anybody know what 'multilayer' caps are made from btw? ceramic? film?
The guy at the store told me they were pretty good as small bypass caps in psu cap banks ...
i'm using 'dual' single stranded cat5 for speaker wire btw. one pair for +, one pair for -. the other two are used as a sort-of shield., connected to the chassis. capacitance shouldn;t be too high.
The guy at the store told me they were pretty good as small bypass caps in psu cap banks ...
i'm using 'dual' single stranded cat5 for speaker wire btw. one pair for +, one pair for -. the other two are used as a sort-of shield., connected to the chassis. capacitance shouldn;t be too high.
I *would* expect the speaker/cable load to be the most significant variable. Therefore, a zobel to compensate for that impedance would be quite logical. However, in that case I don't see why any particular network is recommended for a given IC.
Wouldn't the ideal situation simply (yeah, right!) be a conjugate load at the amplifier designed to flatten the impedance curve of the entire cable/crossover/speaker system as a whole?
I assume this *is* the actual function of the zobel as it is being discussed. Only implemented as a simpler, generalized form to help as it may?
Tim
The zobel network is there to protect the speaker from unnecessary amplified high frequency signals (which can fry your tweeters first). However, values of zobel network has to consider what speaker load is used, or else, you may attenuate usable audio frequency.
This is more true, but in conjunction with the snubber circuit (shunted RC network across the speaker out). Since the zobel coil will be presenting a high impedance to unwanted high frequency output, the zobel R will be functioning to limit the release of unwanted high freq output to certain extent (depends on speaker impedance).
The presence of snubber circuit, will enhance the zobel work, by presenting the shorting effect to this unwanted high frequency (again, the speaker output has to be considered in the values). Snubber will also kill any ringing that may occur in the amplifier system.
This is more true, but in conjunction with the snubber circuit (shunted RC network across the speaker out). Since the zobel coil will be presenting a high impedance to unwanted high frequency output, the zobel R will be functioning to limit the release of unwanted high freq output to certain extent (depends on speaker impedance).
The presence of snubber circuit, will enhance the zobel work, by presenting the shorting effect to this unwanted high frequency (again, the speaker output has to be considered in the values). Snubber will also kill any ringing that may occur in the amplifier system.
Finally found some time to build the amp (and just got my specialized kit casing) I need at least another evening to finalize as I use very thin coax for the low level signals (outer dia 1.5 mm silver coax) which is a nightmare to strip properly.
I want to try a zobel as wel and have on hand the following:
Audyn caps MKP QS 400V 0.1uF which seems fine
Intertechnik MOX 5w 3.3 ohm resistor which may be too high
Alternatively I have a couple of 1ohm 10W MOX resistors
Can I use the 3.3 ohm MOX? or is this not a good resistor to use for this application. (I normaly use these in loudspeaker crossover cirquits)
I will first put them accros the speaker terminals and when the amp is run in I can put them closer to the pcb if I like them
I want to try a zobel as wel and have on hand the following:
Audyn caps MKP QS 400V 0.1uF which seems fine
Intertechnik MOX 5w 3.3 ohm resistor which may be too high
Alternatively I have a couple of 1ohm 10W MOX resistors
Can I use the 3.3 ohm MOX? or is this not a good resistor to use for this application. (I normaly use these in loudspeaker crossover cirquits)
I will first put them accros the speaker terminals and when the amp is run in I can put them closer to the pcb if I like them
fedde: i guess you mean radio is being demodulated by the chip?
last week i added a 2nd order passive lowpass at 60kHz followed by a ad8620 with gain=3 close to the chipamps. i can now hook up any kind of cable, whatever length. before i had to use heavily shielded interconnects otherwise i had RTL FM (!). It didn;t pick anything up on the speakercable.
i can't really hear the difference with and without the buffer. Except that there's no more radio, of course...
last week i added a 2nd order passive lowpass at 60kHz followed by a ad8620 with gain=3 close to the chipamps. i can now hook up any kind of cable, whatever length. before i had to use heavily shielded interconnects otherwise i had RTL FM (!). It didn;t pick anything up on the speakercable.
i can't really hear the difference with and without the buffer. Except that there's no more radio, of course...
Good to hear. Than I don't need a source to get music out of my amp
It is the EM and all other RF pollution that made me decide to use shielded (mini-coax) cable for the inputs to switch to noble pot and to the boards. With this, the solid specialized kits casing and the Zobel I hope that I've take sufficient measures to prevent my amp from acting as a radio.
It is the EM and all other RF pollution that made me decide to use shielded (mini-coax) cable for the inputs to switch to noble pot and to the boards. With this, the solid specialized kits casing and the Zobel I hope that I've take sufficient measures to prevent my amp from acting as a radio.
Well, yes. Sometimes I can receive radio with my amp. But only if my volume is completely to zero (strange eh?). But I was talking about the HF noise in the air and on the mains. Luckily I now use battery for my DAC, so the noise of the mains only has influence on the amplifier (and the transport/PC). Still, the sound quality of the system varies quite a lot during the day. My house (student dorm) is stuffed with computers (>25 I'd guess) and other equipment. We have mobile transmitters nearby, radio transmitters, a wireless LAN network etc. You get my point? ;-)
Fedde
Fedde
Input filters and Zobels are not a luxury. They are essential for troublefree operation of gear and should be implemented. IMO this is standard design practice but I see more and more designs omitting essential parts. Never underestimate the fashion of minimalistic devices
The FTZ standard is another story though.
The FTZ standard is another story though.
fedde said:
Not only that (well... I don't have those interference problems), but, as Nuuk noticed (I was expecting someone to test it and say it), and the reason why I oppened this thread is that in my case the amp really seams to drive "any" speaker now.
Music with extreme dynamics and bass "slam" (I love this word
) is now tight as a rock, to the deepest notes.Oh, the source is good, of course, otherwise, trash-in-trash-out.
carlosfm said:
the reason why I oppened this thread is that in my case the amp really seams to drive "any" speaker now.
Music with extreme dynamics and bass "slam" (I love this word
Oh, the source is good, of course, otherwise, trash-in-trash-out.
I have added the zobel to my amp yesterday. Indeed the bass is much more controlled. Before I had no problems with most Jazz and Clasical music but with the "more modern music" the bass was quit often over the top. In the new situation the amp is driving my 4 ohm speakers much better.
There is something: else some months ago I made some new cables speaker based on TNT-Audio suggestions to use CAT5 twistedpair. However I used wirewrap wire that I twisted and twisted and twisted. The result was sounding awfull! No bass, no middle, infact it sounded like nothing. With the zobel I can use the DIY cable and it sounds great, even after a day.
Peter K.
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