not at all. it is not a "pirate kit", but cviller F5 boards (the smaller first round of blue pcbs). also the cviller rectifier boards and psu board. i combined that with an antek 600va toroid, some of the large heatsinks from the guy on ebay, and other assorted bits. i purchased the fairchild parts kits from techdiy to populate the boards. everything is stock as can be.
as i mentioned, it is biased correctly and was holding very steady. tracking between the two devices was within .002V and the offset was around 1mv per channel. i just plugged it back in today with shorted inputs and everything was fine again. it definitely seems to be some problem from the environment or an upstream component.
the main problem is that i don't have test equipment (other than some multi-meters), and can't really track down any problems on the other components.
i was using my iPhone as a source run through the preamp. i know that creates a lot of RFI, but it was physically far enough away that i thought it wouldn't be a problem. likewise, the preamp rolls off low enough that it shouldn't be amplifying that and sending to the F5.
if adding some input caps and grounding the heat sinks will take care of my problems for sure, i'm tempted to do that. of course, if i could diagnose the actual problem and remove it from the equation...that would be even better!
as i mentioned, it is biased correctly and was holding very steady. tracking between the two devices was within .002V and the offset was around 1mv per channel. i just plugged it back in today with shorted inputs and everything was fine again. it definitely seems to be some problem from the environment or an upstream component.
the main problem is that i don't have test equipment (other than some multi-meters), and can't really track down any problems on the other components.
i was using my iPhone as a source run through the preamp. i know that creates a lot of RFI, but it was physically far enough away that i thought it wouldn't be a problem. likewise, the preamp rolls off low enough that it shouldn't be amplifying that and sending to the F5.
if adding some input caps and grounding the heat sinks will take care of my problems for sure, i'm tempted to do that. of course, if i could diagnose the actual problem and remove it from the equation...that would be even better!
ah, sorry, I had to ask
noise is a strange thing
I dont think F5 likes it very much
or maybe it triggers something in your preamp
but my
I see you are selling some very nice drivers like Raal and AE
surely you must have something better than an iphone
or maybe Im getting old
btw, I wouldnt turn on such like an iphone, with live amps
I think its especilly noisy on power up
and besides, it probably picks up all kinds of noise
actually, i listen to records 90% of the time. the other 10% is background music when cooking or the like. the iPhone works fine for that 
it is just easier to test something for the first time with the iPhone. i've experienced noise from it before, but never smoke! as a matter of fact, this is the first time ever in diy to experience smoke. it's a little unnerving
it is just easier to test something for the first time with the iPhone. i've experienced noise from it before, but never smoke! as a matter of fact, this is the first time ever in diy to experience smoke. it's a little unnerving
that's good to know. guess i won't try it directly connected! wouldn't the preamp isolate the amp from these nasties though?
Talking caps, has anybody tried Mundorf MLytics? Specially the AG variety.
AFAIK, electrolytics capacitors withstand at least 50% more voltage than the rated. That means that a 50v rated cap will work right up to 75v. Have in mind that its life will be reduced, you can't predict how much will it last.
mymindinside, that's why I doubt a 35v will fail with 37v. In fact, it will even work reliably for quite a long time.
Personally, I like the idea of long term functionality, so I use to get them rated at least 50% than the voltage they are going to see. That is 35v caps for 24v usage, 50v caps for 35v usage, etc...
i've experienced noise from it before, but never smoke! as a matter of fact, this is the first time ever in diy to experience smoke. it's a little unnerving
hehe, last week was the firt time I tripped my home breakers. This is not bad for 3 years of non-stop diying. I just slipped one of my probes when measuring at the AC sockets, so the breakers tripped and the fuses popped
I have tripped the breakers quite more times, but none of them was diy related.
What's your suggestion for the speaker protection circuit ?
What about what Frags recommended ?
2x Mono Speaker Protection Module - each for on Channel on eBay.ca (item 300498437584 end time 28-Dec-10 15:21:31 EST)
Thanks,
D.
eRoot, my gut reaction is no to the caps on the jfets...
a cap at the input to ground ought to be sufficient to get most RFI rolled off... beyond that the small caps that NP suggests around the FB loop are the next line of attack... per the design pdf suggestions, etc...
What blew up ur amp will forever remain a mystery until you either thwart it by some means and so draw some conclusion or else beg borrow or steal a 'scope - they're cheap enough these days on epay, so grab one?? You've probably spent more on the power supply for the amp than a decent scope will cost... even an indecent scope might work! AND, they are fun to look at!
_-_-bear
a cap at the input to ground ought to be sufficient to get most RFI rolled off... beyond that the small caps that NP suggests around the FB loop are the next line of attack... per the design pdf suggestions, etc...
What blew up ur amp will forever remain a mystery until you either thwart it by some means and so draw some conclusion or else beg borrow or steal a 'scope - they're cheap enough these days on epay, so grab one?? You've probably spent more on the power supply for the amp than a decent scope will cost... even an indecent scope might work!
AND, they are fun to look at! _-_-bear
Perhaps something you throw in/on during testing and beta tests? (a fuse is cheaper)
Personally, I'd never have a relay in series with the output of one of my power amps... and imo "protection circuits" usually close the barn door after the cattle have left? Ok, it could save a driver in the event of a cosmic melt down, and if you have scary expensive drivers, and a tight budget, perhaps... but not for moi.
YMMV, just my opinion.
_-_-bear
thanks bear. sounds like a plan as adding the cap on the input would be the easiest measure to start. and 2.2uF is ok for that value? how low will that roll off the amp given the 100k input impedance? also, would it be ok to position the cap on the rca jacks, or does it need to be on the board right next to the 100k resistor?
i checked it out again last night, and it was fine being powered on for several hours. it appears only one side smoked. that side's bias voltage was up around .62 - .64, so i re-biased. not sure if that is from the smoke out or what. both channels are now where they need to be. i haven't replaced those burnt resistors yet in case they smoke further on the next go. i figure i can swap those out once i've heard music and everything is working fine.
thanks everyone for your help, and sorry for all the questions!
oh, and as for the o-scope, it's a combination of cost and space really. i'm lacking a proper workshop here so my f-5 has been sprawled out on the dining room table for the past couple of weeks! hahaha. not sure adding another test instrument would help. one day though, i'd love to get one. i'd also love to get a distortion analyzer too so i can really see what's going on!
i checked it out again last night, and it was fine being powered on for several hours. it appears only one side smoked. that side's bias voltage was up around .62 - .64, so i re-biased. not sure if that is from the smoke out or what. both channels are now where they need to be. i haven't replaced those burnt resistors yet in case they smoke further on the next go. i figure i can swap those out once i've heard music and everything is working fine.
thanks everyone for your help, and sorry for all the questions!
oh, and as for the o-scope, it's a combination of cost and space really. i'm lacking a proper workshop here so my f-5 has been sprawled out on the dining room table for the past couple of weeks! hahaha. not sure adding another test instrument would help. one day though, i'd love to get one. i'd also love to get a distortion analyzer too so i can really see what's going on!
1. A good relay has contact resistance 0.001Ohm or so (not worse than speaker terminals contact resistance)
2. Such circuit provides no only protection but a startup delay and momentary shutdown. Yes, F5 is symmetrical and does not have spikes on startup/shutdown, but, for example, Aleph J does.
3. F5 has no input/output capacitors, so any DC on input will make amplified DC on output (somebody reported connecting iPhone made -15VDC at F5 output).
4. Turning on a preamp after F5 cam make significant spikes on the amp. output as well.
PS. I very doubt that somebody can hear any differences in sound with or without relay.
I disagree about the relay.
The contact resistance is not a constant, and will only get worse (for most contact systems) over time. Also it is a single point of contact.
There are better relay contact types, but at minimum I want several contacts in parallel.
Do you think that people - you? - can hear the difference in sound of one type/brand of resistor in the F5 circuit? Thinking here mainly of the larger power resistors... what do you think?
Everyone has to decide what is best for their system and their ears, my choice is no relay.
_-_-bear
The contact resistance is not a constant, and will only get worse (for most contact systems) over time. Also it is a single point of contact.
There are better relay contact types, but at minimum I want several contacts in parallel.
Do you think that people - you? - can hear the difference in sound of one type/brand of resistor in the F5 circuit? Thinking here mainly of the larger power resistors... what do you think?
Everyone has to decide what is best for their system and their ears, my choice is no relay.
_-_-bear
I think that it is an imagination. People believe if they have, for example, better wires the amp and speaker sound better, but with a double blind test they don't hear any difference. Same about resistors, capacitors etc.
Someone even believes in direction of wires and resistors. Someone thinks power cord does matter.
I think that it is an imagination. People believe if they have, for example, better wires the amp and speaker sound better, but with a double blind test they don't hear any difference. Same about resistors, capacitors etc. Someone even believes in direction of wires and resistors. Someone thinks power cord does matter.
Can't hear the difference, huh? I guess they don't exist ..........