Try to order through hi-fi tuning. They carry all the line and have the same prices.
Lgreen,
Well, I try not to answer questions that basically make no sense, such as 'those 1/4W resistors does it matter whether they are metal film or carbon'. I've mentioned it before and will mention it here again, this amplifier is not for the novice builder, if the BOM makes no sense to you then maybe you shouldn't attempt to build it.
But for other questions, or general inquiries, I'm certainly available, either by email or by PM through this forum. Just don't always expect a prompt reply as I'm not behind my PC 24/7, nor do I check email/PM on a daily basis.
Cheers,
Sander.
Well, I try not to answer questions that basically make no sense, such as 'those 1/4W resistors does it matter whether they are metal film or carbon'. I've mentioned it before and will mention it here again, this amplifier is not for the novice builder, if the BOM makes no sense to you then maybe you shouldn't attempt to build it.
But for other questions, or general inquiries, I'm certainly available, either by email or by PM through this forum. Just don't always expect a prompt reply as I'm not behind my PC 24/7, nor do I check email/PM on a daily basis.
Cheers,
Sander.
I think lgreen just want to make sure he gets the right part for the right sonic quality or outcome of the amplifier. I don't think he is a novice builder. If you visit his website, he already done a lot of amplifier projects.
Sure, but the pictures combined with the BOM and the detailed parts list I send with each PCB order should leave little or no head scratching.
As mentioned this amplifier is built using bog standard parts, 1/4W resistors, 2W resistors, BC550C/547C/BC557C, BD139/BD140, etc. These parts are available the world over. As for electrolytic capacitors and ceramics/film capacitors it is clear that for the former anything that matches the rating (100uF/50V for example) will fit the PCB, unless you pick some odd BG or Silmic or Muse capacitor which is 2x the size.
For the latter the film type has been mentioned in the parts list, i.e. PP = polypropylene, MKT = polyester, all other caps are ceramics, either COG or NPO.
Unless I go and find a reference for each individual part on Mouser/Digikey/etc. I don't know how much simpeler I can make things. Again, this is not an amplifier for the novice builder, if the below BOM makes you scratch your head you might want to reconsider building it.
Cheers,
Sander.
The parts list is less than clear.
L1 has no specs other than the mH value;
I have asked him whether a 5A relay FTR-F1CA024V (5A) (mouser) would be ok, or whether 8A is required. No answer.
For the zeners D9/D10 I asked whether 1/4W power rating (mouser 512-1N963B) would be ok. No answer. I see no power rating on the specified parts.
I admit I had trouble with the headers, but for everything else I have specified a link to a mouser part and asked if it was ok. No answer.
I admit some of the questions were kind of novice but I did generate an entire parts list with hyperlinks and asked specific questions as to whether the hyperlinked parts were ok. No answer in months, and this has cost a lot of money. A LOT of $$.
I mean there has been absolute silence. For example - what are the DC values across the schematic to check if its working properly (a prior post)? No answer. What is the startup sequence (a post) no answer.
I do not think it unreasonable to ask for DC values of the L/R boards and for the startup sequence (what to look for as variac goes up to line voltage) as I have completed the build and want to power it up and see if its working correctly. I don't think this is a novice question.
So rather than fighting how about a little more info? I have gotten emails from others who would like similar information.
L1 has no specs other than the mH value;
I have asked him whether a 5A relay FTR-F1CA024V (5A) (mouser) would be ok, or whether 8A is required. No answer.
For the zeners D9/D10 I asked whether 1/4W power rating (mouser 512-1N963B) would be ok. No answer. I see no power rating on the specified parts.
I admit I had trouble with the headers, but for everything else I have specified a link to a mouser part and asked if it was ok. No answer.
I admit some of the questions were kind of novice but I did generate an entire parts list with hyperlinks and asked specific questions as to whether the hyperlinked parts were ok. No answer in months, and this has cost a lot of money. A LOT of $$.
I mean there has been absolute silence. For example - what are the DC values across the schematic to check if its working properly (a prior post)? No answer. What is the startup sequence (a post) no answer.
I do not think it unreasonable to ask for DC values of the L/R boards and for the startup sequence (what to look for as variac goes up to line voltage) as I have completed the build and want to power it up and see if its working correctly. I don't think this is a novice question.
So rather than fighting how about a little more info? I have gotten emails from others who would like similar information.
Last edited:
questions
Just as a followup, I did get the impression early on that there would be no extra help on this project.
Not sure I got the same impression from this thread but I proceeded anyway.
So I accept responsibility for attempting the build; I do not fault him for failure to reply, heck we have schematics and some idea of parts. More than you get on most of the projects here. And this one is quite old so no guarantees.
Also - I was not asking about parts for the "right sonic quality", rather I was asking about parts for compatibility. Mostly it was about if the USA part is a substitute spec wise for the EU original; sonics and tweaking can be dealt with later. I just wanted to bake the cake with the right ingredients.
After my past sins I really would like a little cooperation; lets start over? We are knocking on the door to success....
At this point I believe my parts are OK and just need the DC steady state values for the schematic and startup sequence.
Just as a followup, I did get the impression early on that there would be no extra help on this project.
Not sure I got the same impression from this thread but I proceeded anyway.
So I accept responsibility for attempting the build; I do not fault him for failure to reply, heck we have schematics and some idea of parts. More than you get on most of the projects here. And this one is quite old so no guarantees.
Also - I was not asking about parts for the "right sonic quality", rather I was asking about parts for compatibility. Mostly it was about if the USA part is a substitute spec wise for the EU original; sonics and tweaking can be dealt with later. I just wanted to bake the cake with the right ingredients.
After my past sins I really would like a little cooperation; lets start over? We are knocking on the door to success....
At this point I believe my parts are OK and just need the DC steady state values for the schematic and startup sequence.
Last edited:
Lgreen,
Looking at the pictures you'll quickly realize that this is an axial type and probably any type/brand will do, if not, a precise type would've been specified.
I gave the exact type in the parts list, so it makes sense to look for a relay that matches that, will a 5A type do? Probably, as it is just used to disconnect the power supply from the amplifier in case of a DC error.
If you'd have bothered to check the BZX datasheet you'd have seen these are specified at 500mW, hence the exact type is specified.
Headers are run of the mill Molex types which are in abundance at Mouser/Digikey, however a normal 0.1" pitch header without the plastic shroud works just as well, again, this is all up to what the end user would like to use.
I'm sorry, but if I look at the questions I answered above you clearly have no experience with picking parts and are somewhat of a novice builder.
Startup sequence, c'mon, that's similar to any other DIY amp and common knowledge. I.e. replace fuses with 10R resistors, first test the power supply individually, check for shorts on power rails and output on the amplifier PCB and then hook the thing up. I see you used crocodile leads, that's *not* the way to do it, if one has a intermittent connection you could be generating smoke rather than a working amplifier.
DC values, hmm, let me think, the design calls for a 2x18V/22V transformer for the output stage, hence no load voltage on the power supply will be 18 x 1.41 = 25V or 22 x 1.41 = 31V, the power supply for the frontstage is regulated and will output 2x30V, provided you use the 2x25V transformer as described. Again this is common knowlegde, if you don't know how to calculate transformer primaries after rectification you clearly are a novice builder. The trimpot for the DC offset needs to be at center and DC offset needs to be adjusted after the amplifier has warmed up with the input shorted. But I already mentioned the above a few times in this thread.
Well, I'd be happy to provide info, but the above questions are soo typical for a novice builder and I've answered quite a few of your queries by email already. The moment somebody sends me a parts list as an Excel sheet with questions like 'is this metal film resistor rated at 1/4W and 1% the right type' I simply don't bother to answer. That might seem rude, put the pictures are pretty self explanatory, it uses 1/4W 1% resistors throughout the design, only the emitter resistors are a 2W type.
So I'd be happy to answer questions, but simple questions that just take a little effort (Google search, checking a datasheet for a specified part, looking at pictures and comparing, etc.) I'm going to leave unanswered, sorry, but I just don't have the spare time available to answer those type of queries.
Cheers,
Sander.
Looking at the pictures you'll quickly realize that this is an axial type and probably any type/brand will do, if not, a precise type would've been specified.
I gave the exact type in the parts list, so it makes sense to look for a relay that matches that, will a 5A type do? Probably, as it is just used to disconnect the power supply from the amplifier in case of a DC error.
If you'd have bothered to check the BZX datasheet you'd have seen these are specified at 500mW, hence the exact type is specified.
Headers are run of the mill Molex types which are in abundance at Mouser/Digikey, however a normal 0.1" pitch header without the plastic shroud works just as well, again, this is all up to what the end user would like to use.
I'm sorry, but if I look at the questions I answered above you clearly have no experience with picking parts and are somewhat of a novice builder.
Startup sequence, c'mon, that's similar to any other DIY amp and common knowledge. I.e. replace fuses with 10R resistors, first test the power supply individually, check for shorts on power rails and output on the amplifier PCB and then hook the thing up. I see you used crocodile leads, that's *not* the way to do it, if one has a intermittent connection you could be generating smoke rather than a working amplifier.
DC values, hmm, let me think, the design calls for a 2x18V/22V transformer for the output stage, hence no load voltage on the power supply will be 18 x 1.41 = 25V or 22 x 1.41 = 31V, the power supply for the frontstage is regulated and will output 2x30V, provided you use the 2x25V transformer as described. Again this is common knowlegde, if you don't know how to calculate transformer primaries after rectification you clearly are a novice builder. The trimpot for the DC offset needs to be at center and DC offset needs to be adjusted after the amplifier has warmed up with the input shorted. But I already mentioned the above a few times in this thread.
Well, I'd be happy to provide info, but the above questions are soo typical for a novice builder and I've answered quite a few of your queries by email already. The moment somebody sends me a parts list as an Excel sheet with questions like 'is this metal film resistor rated at 1/4W and 1% the right type' I simply don't bother to answer. That might seem rude, put the pictures are pretty self explanatory, it uses 1/4W 1% resistors throughout the design, only the emitter resistors are a 2W type.
So I'd be happy to answer questions, but simple questions that just take a little effort (Google search, checking a datasheet for a specified part, looking at pictures and comparing, etc.) I'm going to leave unanswered, sorry, but I just don't have the spare time available to answer those type of queries.
Cheers,
Sander.
Quoted below are the parts list for the amplifier and the power supply PCBs with parts values and types specified:
Cheers,
Sander.
Cheers,
Sander.
Sorry. Yes I get the PS voltages. I am not **that** bad. What I would like to see is the DC steady state voltage values on the L/R boards throughout the schematic.
I have checked and double checked every part I bought, measured with a vernier for lead spacing and size vs. the board, since no sizing is specified for majority of parts; provided hyperlinks for every part I asked about. Questions were mainly to confirm parts were ok I never asked for you to find a part for me. I don't think its valid to complain about the parts questions.
I have this completely built and I am getting the feeling that the + half of the circuit is not behaving like the - half, some DC steady state values on the the L/R boards would be helpful.
Startup - do all 4 LEDs light at the same time or do some go 1st and some follow at higher voltages? What Supply voltage causes each LED to illuminate? What DC voltage causes the outputs to begin to conduct? What should one look for in the behavior of the circuit as voltage increases from 0 to the standard values? I was not asking how to turn the thing on; I am able to manage that despite being a novice. DC values on L/R boards (not ps board)?
Again, I do not mean to be cricital or start arguments. I'd like to make sure this is working correctly as it is completely built and undergoing testing. I have not had much time recently (since last scope pic) so that is why there have been no posts.
Last edited:
Lgreen,
I'd be happy to debug your build, let me start by answering the questions in your previous reply:
Unless you ramp up the supply voltage slowly with a variac all LEDs should light at the same time. I don't know what will happen if you slowly ramp up the supply voltage, it could be that part of the design latches up as this isn't normal behaviour. What is critical though is that both frontstage and powerstage supply voltages are available.
I don't have a fully working ExtremA here at the moment, but I'm collecting parts for one and should have one up and running in a week or two. If you can wait that long I'd be happy to compare notes and give you DC voltages at any desired point.
Cheers,
Sander.
I'd be happy to debug your build, let me start by answering the questions in your previous reply:
Unless you ramp up the supply voltage slowly with a variac all LEDs should light at the same time. I don't know what will happen if you slowly ramp up the supply voltage, it could be that part of the design latches up as this isn't normal behaviour. What is critical though is that both frontstage and powerstage supply voltages are available.
I don't have a fully working ExtremA here at the moment, but I'm collecting parts for one and should have one up and running in a week or two. If you can wait that long I'd be happy to compare notes and give you DC voltages at any desired point.
Cheers,
Sander.
Weird Results
Its weird, sometimes when I power up the variac the voltage on the outputs will drift + or other times it will drift -, and you get DC on the output but no AC. In such a case only 2 of the 4 LEDs light.
Sometimes it works fine and all the LEDs light and there is no voltage drift and here it plays music fine. I even connected it to some small test speakers and it worked into them.
I can sit and try the variac and the first try the voltage will go up, the second it will go down and third it will work fine.
I figure it must have something to do with grounding but I cannot figure it out. I will try the 2nd channel and see if it behaves the same.
Its weird, sometimes when I power up the variac the voltage on the outputs will drift + or other times it will drift -, and you get DC on the output but no AC. In such a case only 2 of the 4 LEDs light.
Sometimes it works fine and all the LEDs light and there is no voltage drift and here it plays music fine. I even connected it to some small test speakers and it worked into them.
I can sit and try the variac and the first try the voltage will go up, the second it will go down and third it will work fine.
I figure it must have something to do with grounding but I cannot figure it out. I will try the 2nd channel and see if it behaves the same.
Are you ramping up the voltage slowly? I already mentioned I cannot predict what will happen in that case, as the circuit might latch up. Either way this seems like a wrong part stuffed someplace to me.
Cheers,
Sander.
Cheers,
Sander.
Ramping up slowly.
I've got rails at about 19.5 VDC (variac set to 120V), 1.3 ohm emitter resistors and measure a .65V drop across all 4 quadrants of resistors (4 resistors each). I trace the input all the way through (as best I can) and see nice sine waves; DC offset can be adjusted fine until it is essentially gone.
With a 4 ohm load I have observed the positive terminal swing of + and - 15 volts w/r to ground before clipping (the top of the clipped waveform oscillates a little). Negative is same w/r ground but out of phase.
Does this seem right?
I do get the latching behavior on both channels. Even when not ramping the variac it has happened. It happens now and again. If it does you just turn power off, wait a few seconds and turn on and hope for the best.
I've got rails at about 19.5 VDC (variac set to 120V), 1.3 ohm emitter resistors and measure a .65V drop across all 4 quadrants of resistors (4 resistors each). I trace the input all the way through (as best I can) and see nice sine waves; DC offset can be adjusted fine until it is essentially gone.
With a 4 ohm load I have observed the positive terminal swing of + and - 15 volts w/r to ground before clipping (the top of the clipped waveform oscillates a little). Negative is same w/r ground but out of phase.
Does this seem right?
I do get the latching behavior on both channels. Even when not ramping the variac it has happened. It happens now and again. If it does you just turn power off, wait a few seconds and turn on and hope for the best.
Last edited:
Something is amiss, how about you try powering the frontend up first, all LEDs should light at the same time and stay lit, then power the power stage. Don't ramp up slowly, as mentioned I can't predict the behaviour that way around and it might latch up.
Cheers,
Sander.
Cheers,
Sander.
hmmm....
OK, after further review the latch-up (where the circuit starts incorrectly) can be caused by 2 things: (1) it is dependent on how fast you start up with the variac, sometimes the variac works and sometimes it does not. Once the primary goes to about 30-40VAC if all 4 LEDs are lit you are all set, if only 2 are lit (Leds #1 and #2) the other 2 are not going to fire (#3, #4) or they will be very dim. (2) It can also happen on instant startup if you turn the amp on on within a few seconds of having turned it off.
I have been unable to cause the latch up if I don't use a variac but only if I wait about 10 seconds after turnoff to turn it back on. At this point I'm going to proceed with construction and watch for any further occurrences of this.
OK, after further review the latch-up (where the circuit starts incorrectly) can be caused by 2 things: (1) it is dependent on how fast you start up with the variac, sometimes the variac works and sometimes it does not. Once the primary goes to about 30-40VAC if all 4 LEDs are lit you are all set, if only 2 are lit (Leds #1 and #2) the other 2 are not going to fire (#3, #4) or they will be very dim. (2) It can also happen on instant startup if you turn the amp on on within a few seconds of having turned it off.
I have been unable to cause the latch up if I don't use a variac but only if I wait about 10 seconds after turnoff to turn it back on. At this point I'm going to proceed with construction and watch for any further occurrences of this.
Last edited:
Hello Sander
You may have answered this question already but on the output stage the emmiter resistors (eg R36) of the output devices you use 4 * 1R 1W instead of wire wound types is there a reason for this.
Regards
Arthur
You may have answered this question already but on the output stage the emmiter resistors (eg R36) of the output devices you use 4 * 1R 1W instead of wire wound types is there a reason for this.
Regards
Arthur
Arthur,
Yes, the power handling capacity of MOX (metal oxide film) resistors is far higher than wirewound resistors. Wirewound will degrade over time and are particularly not suited for pulsed operation as any weakness in the wire will result in a weak spot and eventually an open circuit. The MOX are immune to this, I'm using 4x to get to the power level I wanted to arrive at (~5W) which also makes it easier to build different values for scaling the ExtremA's output power (you can mix and match in pairs, i.e. 2x1R + 2x1R5).
Cheers,
Sander.
Yes, the power handling capacity of MOX (metal oxide film) resistors is far higher than wirewound resistors. Wirewound will degrade over time and are particularly not suited for pulsed operation as any weakness in the wire will result in a weak spot and eventually an open circuit. The MOX are immune to this, I'm using 4x to get to the power level I wanted to arrive at (~5W) which also makes it easier to build different values for scaling the ExtremA's output power (you can mix and match in pairs, i.e. 2x1R + 2x1R5).
Cheers,
Sander.
- Status
- Not open for further replies.