I'm looking at building an inexpensive power amp. It will be first electronic project. I've been recommended a LM3886 based design - based on National's example.
A kit site is offering a LM3875 based design. National's site is pushing the LM4780. Would anyone comment on these?
I'm looking for something 'musical' (pace, tune, timing). Anyone familiar with the 'Flat Earth' cult will know exactly what sort of sound I'm after.
I have a soldering iron and a $5 multi-meter. Not much gear, but it's all I can afford. My knowledge of electronics is very basic. I mean, I can follow a schematic, but that's it.
My current source is FLAC through a sound card (a little hissy, but okay for now). My current amp is an old Sansui receiver, which I found on the street. I managed to mod it into a power amp. It sounds quite tuneful, but the tone controls are annoying (bypassing them seems to be beyond my ability). So, that's why I'm looking at starting from scratch.
So, what do you think? Are any of the above mentioned parts suitable for me? Am I barking up the wrong tree completely? Would much appreciate your advice.
A kit site is offering a LM3875 based design. National's site is pushing the LM4780. Would anyone comment on these?
I'm looking for something 'musical' (pace, tune, timing). Anyone familiar with the 'Flat Earth' cult will know exactly what sort of sound I'm after.
I have a soldering iron and a $5 multi-meter. Not much gear, but it's all I can afford. My knowledge of electronics is very basic. I mean, I can follow a schematic, but that's it.
My current source is FLAC through a sound card (a little hissy, but okay for now). My current amp is an old Sansui receiver, which I found on the street. I managed to mod it into a power amp. It sounds quite tuneful, but the tone controls are annoying (bypassing them seems to be beyond my ability). So, that's why I'm looking at starting from scratch.
So, what do you think? Are any of the above mentioned parts suitable for me? Am I barking up the wrong tree completely? Would much appreciate your advice.
I think a 3875 or 3886 kit would be a great first project. I built a 3886 kit and really love the sound. You really don’t need to have any great understanding of electronics to build a kit from chipamp or audiosector, as long as you pay attention.
What kind of soldering iron do you have? A 30-40 watt fine tip iron would work best. Too much power or too large a tip and it will be tough to solder the pcb.
Don’t forget to include the cost of a transformer/Potentiometer/RCAs/Binding posts/case/wire/…. in your budget. About $100.
One word of warning, projects like this are like crack. Once you finish one it’s really hard to stop.
What kind of soldering iron do you have? A 30-40 watt fine tip iron would work best. Too much power or too large a tip and it will be tough to solder the pcb.
Don’t forget to include the cost of a transformer/Potentiometer/RCAs/Binding posts/case/wire/…. in your budget. About $100.
One word of warning, projects like this are like crack. Once you finish one it’s really hard to stop.
I'm in the same position Zoodle. I'm looking at doing two monoblocks, probably the LM4780 from audiosector.com. I can do crossovers, but that's the limit of my experience. From what I've gathered, construction for any of the chip kits at chipamp or audiosector require only basic skills.
I've been reading everything I can find comparing the chips, and it's all very subjective. My plan is to jump in and do it.
I'll also be doing FLAC through the sound card, though after the amps I'm considering a DAC/preamp combo.
I've been reading everything I can find comparing the chips, and it's all very subjective. My plan is to jump in and do it.
I'll also be doing FLAC through the sound card, though after the amps I'm considering a DAC/preamp combo.
For a first try I would also say go with a reputable well known kit as plenty have been built. That way if you have a problem with it, the answer will most likely be out there. You can get adventuous with the next if you want, but keep things simple for a first go.
If you are using a pc as source be aware that they can have a lot of DC on the output. If this means nothing to you, search on "DC offset" and "input capacitors". Also have a look for "lightbulb tester" and put one together before you start your amp build.
What enclosure are you thinking of using? If you are making your own this will be a bigger job than assembling the circuit boards. Read up on safety grounding, it's vital you don't electrocute your loved ones as they are seldom happy about it.
Have a browse at Decibel Dungeon for answers to many questions and maybe some inspiration in the gallery pages.
Netbug is right about it being an addictive hobby. If your first one works and sounds as it should it's very pleasing. If you take your time and be careful you are in for a very pleasant surprise, and a grin from ear to ear.
John
If you are using a pc as source be aware that they can have a lot of DC on the output. If this means nothing to you, search on "DC offset" and "input capacitors". Also have a look for "lightbulb tester" and put one together before you start your amp build.
What enclosure are you thinking of using? If you are making your own this will be a bigger job than assembling the circuit boards. Read up on safety grounding, it's vital you don't electrocute your loved ones as they are seldom happy about it.
Have a browse at Decibel Dungeon for answers to many questions and maybe some inspiration in the gallery pages.
Netbug is right about it being an addictive hobby. If your first one works and sounds as it should it's very pleasing. If you take your time and be careful you are in for a very pleasant surprise, and a grin from ear to ear.
John
Thanks everyone for the warm welcome and the info.
Netbug,
Fortunately, my S.Iron is a temp variable. I think it's fifty watts.
Mattmcl,
Looks like we're on the same road. I've realized I need a separate DAC, so I'll be looking at building one of those too. I was hoping that the vol control in my FLAC software (Rhythmbox) operated in the digital domain (prior to SPDIF). Wishful thinking?
John, Thanks for the advice (bulb tester), and I hear you on the safety issue. Luckily, I've got my pick of enclosures: the Sansui, plus two other amps (busted). I hope to cannibalize them for transformers and heat-sinks. I suppose using the P/S smoothing caps would be a false economy.
I may go with the 3886 because so many people have built amps using it, but I'm open to new ideas.
Netbug,
Fortunately, my S.Iron is a temp variable. I think it's fifty watts.
Mattmcl,
Looks like we're on the same road. I've realized I need a separate DAC, so I'll be looking at building one of those too. I was hoping that the vol control in my FLAC software (Rhythmbox) operated in the digital domain (prior to SPDIF). Wishful thinking?
John, Thanks for the advice (bulb tester), and I hear you on the safety issue. Luckily, I've got my pick of enclosures: the Sansui, plus two other amps (busted). I hope to cannibalize them for transformers and heat-sinks. I suppose using the P/S smoothing caps would be a false economy.
I may go with the 3886 because so many people have built amps using it, but I'm open to new ideas.
Zoodle said:
SPDIF is never scaled. It is always "full volume" so to speak. You really never shouod scale digital audio data. Volume control must be analog. The reason is simple, for every 6DB of volume reduction you in effect loose one bit of sample width. By the time you are down to soft, small room volume you have 68-bit sound that is "telephone quality" at best. Inside SPDIF the music is representy by a series a integers. When you divide (scale) integers you might get a fraction (3/2 = 1.5) but these get rounded back to integers so with digital audio 3/2=2. This leads to a 50% distortion which is unacceptable. So it's not done, volumes are analog.
It's odd how people say they are basing an amp on a "3886". Those parts sell for $5 and the amp cost $100 or more to build. Only 5% (or 10% if you build stereo) of the amp is "3886". When you listen to an amp what you are really listing to is the power supply. It's the PS that makes the big volume power, that "3886" is really a kind of throttle that sits between the PS and your speakers. Same applies to tube based amps. In all cases, tubes, transistors or chips that gbig exppensive parts are the PS and speakers.
If this is your first project, I'd suggest starting very small. Build two amps. make your first one very small. Maybe use a 12V power cube ("wall wort") as your power supply and build a 1/2 watt amp. Then later build the amp you really want. You can re-use the parts if need be.
OK, I'll be a bit more specific, this area of Rod's site is very informative:
http://sound.westhost.com/articles.htm
I use a lot of Rod Elliot's PCBs I find them really easy to build and they always do what is claimed. I haven't tried any of his amp projects though.
One good thing about the ESP projects is that if you are living in Australia the designs keep in mind what components are readily and cheaply available. All of the boards I have made up Iv'e been able to walk into one of the 3 main electronics stores that are in every town here and buy all the components needed.
My first amp build was a 41hz amp9-basic. It probably wasn't the easiest to start with but being able to just connect it to a battery instead of using a mains powered transformer was a big plus.
col.
Mattmcl,
Yeah, I thought it was too good to be true. So I'll be looking at some sort of minimalist DAC and Vol control. I've also had a good look at audiosector - it's tempting to buy a parts kit from there and assemble it as point-to-point.
Col
I'll take a look at those articles. Americans and Brits are lucky - they don't know what a desert Aus can be for the DIYer. I thought DSE would have everything I need (wrong!)
I like the idea of battery power for audio (cleaner?)
AndrewT
Thanks for reminding me: Decibel Dungeon.
Tekko,
I'll be on guard!
Chris,
That's something I didn't know - SPDIF vol issues.
P/S: When I worked in hi-fi retail I remember how the best sounding amps always had P.supplies that seemed 'too big' for the job.
Thanks again all. You've saved me making some mistakes and wasting time/money.
Yeah, I thought it was too good to be true. So I'll be looking at some sort of minimalist DAC and Vol control. I've also had a good look at audiosector - it's tempting to buy a parts kit from there and assemble it as point-to-point.
Col
I'll take a look at those articles. Americans and Brits are lucky - they don't know what a desert Aus can be for the DIYer. I thought DSE would have everything I need (wrong!)
I like the idea of battery power for audio (cleaner?)
AndrewT
Thanks for reminding me: Decibel Dungeon.
Tekko,
I'll be on guard!
Chris,
That's something I didn't know - SPDIF vol issues.
P/S: When I worked in hi-fi retail I remember how the best sounding amps always had P.supplies that seemed 'too big' for the job.
Thanks again all. You've saved me making some mistakes and wasting time/money.
There are a few simple bare board kits for sale on ebay using LM3886 chips. Some come with a power supply PC, some are just the amplifier boards. If you have some surplus bridge rectifiers you don't want the power supply PCB's (and if you can't build a power supply using point to point wiring you shouldn't be building anything anyway).
I just finished a stereo gain clone using two of the simple ebay LM3886 pcb's. It came out great, sounds real good. I soldered the feedback resistor directly to the LM3886 pins rather than to the pc board because I thought the traces to it were too long, but it probably would have worked OK on the pcb. I will post some pic's on here later.
I just finished a stereo gain clone using two of the simple ebay LM3886 pcb's. It came out great, sounds real good. I soldered the feedback resistor directly to the LM3886 pins rather than to the pc board because I thought the traces to it were too long, but it probably would have worked OK on the pcb. I will post some pic's on here later.
We all have to start somewhere and a kit gives the best chance of success for a first go.
I started with a 3875 kit, then a 3875 point to point, then a 1875 point to point with a couple of pre amps and a playstation in between. Not forgetting a couple of sets of speakers.....
Adictive? No I could stop anytime I want to, maybe just one more...........
John
john blackburn said:
My first gain clone built with ebay lm3886 amplifier pcb's sounds real good. The boards are not as nicely laid out as the BrianGT ones, but if you solder the feedback resistors directly to the chip, they'll do. Now I want to make a 3 channel amp for my HT, probably with 6 boards for 3 bridged channels. Later I'll add 2 or 4 more channels for the surrounds. (My Onkyo receiver is ok, but can't really drive all the speakers at once full bore.)
I like to build speakers too. I've built a pair with 6.5" woofers for my front channels, and later added a third for the center. Also a pair with 5.25" woofers for the surrounds. Also have an isobaric subwoofer almost finished (it still needs an active xover and a power amp ... another gain clone or two) for my PC.
Nothing wrong with kits for starters. Most PS boards are set up to use those T0-220 diodes intended for use in switching supplies (which are over priced IMHO). I have a load of common bridge rectifiers which are just as good if you add snubber caps. These won't fit the PC boards so I just point to point wire my PS. The PS circuit is so simple, a PCB simply isn't worth the cost. Guess if you have to cut your teeth on doing p-p wiring, the PS is the place to do it. (Just make sure the big caps and the rectifiers are not soldered in backwards!).
Iv'e been using these handy PCBs for power supplies:
http://www.altronics.com.au/index.asp?area=item&id=K3015
They have really fat tracks and are reasonably priced. Also, they look neat and tidy when mounted in the case, that and a chassis mounted KBPC3504 with some snubbers.
col.
http://www.altronics.com.au/index.asp?area=item&id=K3015
They have really fat tracks and are reasonably priced. Also, they look neat and tidy when mounted in the case, that and a chassis mounted KBPC3504 with some snubbers.
col.
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