PD's novice amp challenge -- a twist
Peter,
I would like to be part of this chip amp "challenge" build, and plan to buy a 3874 kit from you - i.e., not asking you to send me the boards gratis.
I mostly want to participate in the documentation of the build, but add the perspective of a totally blind builder. Note that I do have experience as my training is as an EE and my days as a hobbyist go back to the late 60s. What I think I can contribute is a perspective that requires verbal explanations to supplement all the pictures and graphs. This greatly helps the verbal/auditory learners as well as the visual ones, and if my classroom experience from grad school is any indication, both modalities complement each other and people generally learn quicker and deeper.
What this will mean is that I will be prompting you and others for verbal descriptions of things like components, wire dressing, wire colors, PCB features and orientation, and whatever else might be needed to make the sconstruction steps perfectly clear from a written perspective. I will also attempt to interpret these descriptions and rewrite and/or edit for clarity.
If this sounds acceptable to you, just give me the word and I'm in. This may turn out to be the first guide of it's type.
-- Jim
P.S. -- Do I pay the international shipping rate in the U.S.?
Peter,
I would like to be part of this chip amp "challenge" build, and plan to buy a 3874 kit from you - i.e., not asking you to send me the boards gratis.
I mostly want to participate in the documentation of the build, but add the perspective of a totally blind builder. Note that I do have experience as my training is as an EE and my days as a hobbyist go back to the late 60s. What I think I can contribute is a perspective that requires verbal explanations to supplement all the pictures and graphs. This greatly helps the verbal/auditory learners as well as the visual ones, and if my classroom experience from grad school is any indication, both modalities complement each other and people generally learn quicker and deeper.
What this will mean is that I will be prompting you and others for verbal descriptions of things like components, wire dressing, wire colors, PCB features and orientation, and whatever else might be needed to make the sconstruction steps perfectly clear from a written perspective. I will also attempt to interpret these descriptions and rewrite and/or edit for clarity.
If this sounds acceptable to you, just give me the word and I'm in. This may turn out to be the first guide of it's type.
-- Jim
P.S. -- Do I pay the international shipping rate in the U.S.?
Peter,
Excellent! I've been wanting to do something like this for a long time, and I'll end up with a nice amp too. I've done this sort of thing working with an assistant to help me label things and orient and mark the PC board (which I will also do here), but I want to see how this works via a virtual medium.
Thanks,
Jim
Excellent! I've been wanting to do something like this for a long time, and I'll end up with a nice amp too. I've done this sort of thing working with an assistant to help me label things and orient and mark the PC board (which I will also do here), but I want to see how this works via a virtual medium.
Thanks,
Jim
A related, but more important safety concern, is personal safety.
Please look up the "light bulb test" unit. And please follow "safety earth" grounding discussions of Mr. AndrewT.
EDIT: Use the search feature here at diyaudio.com.
In the U.S., an unsafe home wiring situation is whenever a 20 amp circuit breaker (at your breaker box) is combined with 14ga wire. However, a similar scenerio is commonplace in other countries.
If you don't know, then assume its unsafe.
In this scenerio, the neutral can fail or falter, leaving the amplifier hott with voltage while the other nearby components are still grounded. When in doubt, its important to use the "safety earth" to ground the amplifier.
Also, look up "ground loop breaker" and its usage.
This scenerio is why I prefer wooden enclosures--not a substitute, but does decrease the risk of completing a circuit with your fingers.
EDIT: With a wooden amplifier enclosure, then the amplifier can be grounded, without grounding its owner.
EDIT2: Since the wooden enclosure helps avoid confusion, then my position is to use safety earth grounding, with the ground loop breaker, and do so inside a wooden enclosure.
Now, if you have absolutely no idea what any of this means, go and purchase a "carpenter's power stick with circuit breaker" from your local hardware store. This has the obvious little button circuit breaker (an additional little round button--not just a power switch). This type is for carpenters safety with power tools, and its from the hardware store. Also, its not a substitute, but it will help with safety. You can use one on your hifi system and use one at your workbench.
Things to look up:
Safety earth grounding
ground loop breaker
carpenter's power stick with onboard circuit breaker
light bulb based test unit
*all of the above
Please look up the "light bulb test" unit. And please follow "safety earth" grounding discussions of Mr. AndrewT.
EDIT: Use the search feature here at diyaudio.com.
In the U.S., an unsafe home wiring situation is whenever a 20 amp circuit breaker (at your breaker box) is combined with 14ga wire. However, a similar scenerio is commonplace in other countries.
If you don't know, then assume its unsafe.
In this scenerio, the neutral can fail or falter, leaving the amplifier hott with voltage while the other nearby components are still grounded. When in doubt, its important to use the "safety earth" to ground the amplifier.
Also, look up "ground loop breaker" and its usage.
This scenerio is why I prefer wooden enclosures--not a substitute, but does decrease the risk of completing a circuit with your fingers.
EDIT: With a wooden amplifier enclosure, then the amplifier can be grounded, without grounding its owner.
EDIT2: Since the wooden enclosure helps avoid confusion, then my position is to use safety earth grounding, with the ground loop breaker, and do so inside a wooden enclosure.
Now, if you have absolutely no idea what any of this means, go and purchase a "carpenter's power stick with circuit breaker" from your local hardware store. This has the obvious little button circuit breaker (an additional little round button--not just a power switch). This type is for carpenters safety with power tools, and its from the hardware store. Also, its not a substitute, but it will help with safety. You can use one on your hifi system and use one at your workbench.
Things to look up:
Safety earth grounding
ground loop breaker
carpenter's power stick with onboard circuit breaker
light bulb based test unit
*all of the above
There really would be very little point. If he knew the answer to that he would be nerdy enough to build his own chipamp. And what's the point of needless questioning? It only takes up valuable building time.
I trust CarlosFM not to steer me wrong. There are some people you don't need to question, just to trust their expertise.
John
Prevent speaker fires.
You can measure DC voltage output a the RCA jacks of each source (or preamp) used with the amplifier. It should be zero at the smallest scale.
If you don't know. . . or if you plan to plug in more than one source. . . then, the standard practice of a dc block (input filter cap) is indicated in order to prevent a loudspeaker fire.
Let's take the Audiosector board for example.
To install DC blocking:
1). Install a 15k resistor at the spot marked "R2"
2). Install a 4.7uF cap at the spot marked "R1"
A Sanchez said:
You can measure DC voltage output a the RCA jacks of each source (or preamp) used with the amplifier. It should be zero at the smallest scale.
If you don't know. . . or if you plan to plug in more than one source. . . then, the standard practice of a dc block (input filter cap) is indicated in order to prevent a loudspeaker fire.
Let's take the Audiosector board for example.
To install DC blocking:
1). Install a 15k resistor at the spot marked "R2"
2). Install a 4.7uF cap at the spot marked "R1"
A Sanchez
I went for a pre amp because I needed a few inputs and I had read conflicting opinions about whether they needed one or not. In fact I had read so many differering accounts of buffered, passive, pot only etc etc that I didn't know whether I was coming or going.
Then I came by Carlos FMs Uno on Decibel dungeon and the line that caught my eye was "will go with any kind of power amp" I guess there are late edwardian steam powered or pedal cranked topologies that it wouldn't suit but lets leave them out of the equation shall we?
It's simple enough to build on stripboard and uses no exotica type components But does have lovely big fat DC blocking capacitors on the outs. Mine worked first time but I should have built 2 of them. I made mistakes in the layout which I wouldn't do the second time. Simple things like just not giving myself enough space in the enclosure and then ending up with a dodgy joint because I couldn't get in with the iron without burning something else, usually me.
Just my own findings and in no way presented as advice!
John
I went for a pre amp because I needed a few inputs and I had read conflicting opinions about whether they needed one or not. In fact I had read so many differering accounts of buffered, passive, pot only etc etc that I didn't know whether I was coming or going.
Then I came by Carlos FMs Uno on Decibel dungeon and the line that caught my eye was "will go with any kind of power amp" I guess there are late edwardian steam powered or pedal cranked topologies that it wouldn't suit but lets leave them out of the equation shall we?
It's simple enough to build on stripboard and uses no exotica type components But does have lovely big fat DC blocking capacitors on the outs. Mine worked first time but I should have built 2 of them. I made mistakes in the layout which I wouldn't do the second time. Simple things like just not giving myself enough space in the enclosure and then ending up with a dodgy joint because I couldn't get in with the iron without burning something else, usually me.
Just my own findings and in no way presented as advice!
John
Hi Daniel.
No photos were taken as it was a super low budget build. The enclosure is an old VCR with the plastic front panel sawn off and galvanised steel plate front and back panels.
This is topped off with cheap and nasty skirted knobs for the volume and input source and volume markings in hand done marker pen on the finest quality masking tape. Finally a big and dodgy chrome toggle switch tops it off. It's sort of anti bling.
Theres a matching galvanised LM3875 power amp which is bigger (older all metal VCR) but with no masking tape. That brings me round to the comments on layout planning. I used the bigger all metal enclosure for the chipamp as I didn't know what the heat situation would be. Though it left me with more circuitry to get into a smaller enclosure for the pre amp. The power amp gets vaguely warm to the touch after 15 hours at nearfield volumes so I think the heatsink/transformer/speaker combo suit each other and it would have been fine in the smaller case.
Just to throw some numbers in it's a single shared 22v dual secondary 300va Airlink transformer with CSS FR125 (7 ohm?) speakers and heatsinks from our own Vikash at Mad about Sound
http://www.madaboutsound.com/
A belting honest bloke to do business with but he sadly no longer does the chipamp stuff.
As a final ramble on the subject of enclosures I would say if you value your time greatly bite the bullet and buy yourself an off the shelf enclosure. If you have plenty of free time and dont mind drilling countless holes and having metal shards embedded in every carpet in the house then make or modify your own.
If you want photos you can have them, it's coming out to give it some more inputs when I can bring myself to unplug it. But it means more drilling of holes and listening to a denon PMA250 whilst it's legged up.
John
No photos were taken as it was a super low budget build. The enclosure is an old VCR with the plastic front panel sawn off and galvanised steel plate front and back panels.
This is topped off with cheap and nasty skirted knobs for the volume and input source and volume markings in hand done marker pen on the finest quality masking tape. Finally a big and dodgy chrome toggle switch tops it off. It's sort of anti bling.
Theres a matching galvanised LM3875 power amp which is bigger (older all metal VCR) but with no masking tape. That brings me round to the comments on layout planning. I used the bigger all metal enclosure for the chipamp as I didn't know what the heat situation would be. Though it left me with more circuitry to get into a smaller enclosure for the pre amp. The power amp gets vaguely warm to the touch after 15 hours at nearfield volumes so I think the heatsink/transformer/speaker combo suit each other and it would have been fine in the smaller case.
Just to throw some numbers in it's a single shared 22v dual secondary 300va Airlink transformer with CSS FR125 (7 ohm?) speakers and heatsinks from our own Vikash at Mad about Sound
http://www.madaboutsound.com/
A belting honest bloke to do business with but he sadly no longer does the chipamp stuff.
As a final ramble on the subject of enclosures I would say if you value your time greatly bite the bullet and buy yourself an off the shelf enclosure. If you have plenty of free time and dont mind drilling countless holes and having metal shards embedded in every carpet in the house then make or modify your own.
If you want photos you can have them, it's coming out to give it some more inputs when I can bring myself to unplug it. But it means more drilling of holes and listening to a denon PMA250 whilst it's legged up.
John
john blackburn said:
I think I'd have some fun with the photo printer and transparency film to make some 1960's style labels for those knobs. Something like Lo, Medium, Hi, and "The Most."
Ooh, and then some yellowish orange LED's inside, which would shine the warm glow out through any vents. . .
Next up, I'd be tempted to put some wood down the sides, with some sort of crazy angle on the front, just like late 50's era Heathkit cases. And, howabout a jewled face "pilot" light to indicate the power is really, really on.
I'm not making fun, but just saying that the style of metal, knobs, and switches. . . can be pretty if its decorated on a matching theme.
EDIT: although that could be carrying "system symmetry" a bit too far. Still, I've just got to do up a volume knob that has "The Most" on it!
None of that would make it sound any better though and I built these to listen to rather than look at. As the saying used to go in the motorbike world "chrome wont get you home"
The agricultural styling started out through financial necessity but is now quite deliberate. Why would you steal something that the local second hand shop wouldn't buy from you?
I've got a MickF style playstation 1002 whos modifications have hinged around not having to remove the 10 Pound pawn shop price sticker stuck to the top of it for the same reason.
Sorry for the off topic ramblings to the original poster, I'm done.
John
The agricultural styling started out through financial necessity but is now quite deliberate. Why would you steal something that the local second hand shop wouldn't buy from you?
I've got a MickF style playstation 1002 whos modifications have hinged around not having to remove the 10 Pound pawn shop price sticker stuck to the top of it for the same reason.
Sorry for the off topic ramblings to the original poster, I'm done.
John
Forgot to mention there are a few articles on chipamps on Vikashs non commercial website which may be of interest to some on this thread.
http://www.vikash.info/audio/
Now I'm done
John
http://www.vikash.info/audio/
Now I'm done
John
I don't see anything off topic and I'm glad subjects came up.
Dan had said in an earlier post that hook-ups were more of a concern than building the amps. I saw things the same way. That, heat issues and newbee minimal soldering skills all come into play. You really almost need to think backwards in the assembly process when designing the amp unless you determine in advance that you want the amp to serve only a single purpose ie one source, one set of speaks, no pre-amp or possibilities of adding one. Nothing wrong with that either if a new designs sole purpose is to get a newbees feet wet to go on and build amps capable of serving more than one purpose.
Gainclones can serve a multitude of purposes based upon their design.
I've been hesitant to post anything here as it now appears there will be 2 threads once Peter gets his started on building a newbee amp. The subject has become to a degree muddied up. It's purpose, I hope, is to still meet the needs of a newbee wanting to build his own GC . Peter has said he wants newbee input on his thread to support elimination of confusion for that builder.
Eliminating confusion was what the whole subject was about to begin with.
So, Dan, that brings us to the question of how much input you still want in this thread regards your design?
Bluto
Dan had said in an earlier post that hook-ups were more of a concern than building the amps. I saw things the same way. That, heat issues and newbee minimal soldering skills all come into play. You really almost need to think backwards in the assembly process when designing the amp unless you determine in advance that you want the amp to serve only a single purpose ie one source, one set of speaks, no pre-amp or possibilities of adding one. Nothing wrong with that either if a new designs sole purpose is to get a newbees feet wet to go on and build amps capable of serving more than one purpose.
Gainclones can serve a multitude of purposes based upon their design.
I've been hesitant to post anything here as it now appears there will be 2 threads once Peter gets his started on building a newbee amp. The subject has become to a degree muddied up. It's purpose, I hope, is to still meet the needs of a newbee wanting to build his own GC . Peter has said he wants newbee input on his thread to support elimination of confusion for that builder.
Eliminating confusion was what the whole subject was about to begin with.
So, Dan, that brings us to the question of how much input you still want in this thread regards your design?
Bluto
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