Hello all,
Over the past several months, I've had 3 different amp projects in various stages (long, cold New England winter months. 🙂 ) going. Over the past couple of weeks I've finished up 2 of them, and the 3rd is waiting for its proper enclosure/chassis. The amps are; (1) SymAsym, (2) ICEpower, and (3) an LM4780. Due to my hectic schedule, I have not had the time to do any focused listening to any of them yet, over and above some burn-in with the little speakers (Auvio - RS closeout), I have at my bench for testing. However, I was surprised by the sound of he 4780 in particular.
I know the LM3886 chip-amp has somewhat of a cult-like following here on DIYAudio forums, but I was not aware until I heard with my own ears the sound it can produce. I used the twin brother of the LM3886, the LM4780 in my build - which is essentially the same chip in stereo packaging. I used the PA-03 (Pavel) version of the amp which is claimed to have an excellent layout and implementation of the chip. I kept pushing it to the rear of the line in my build queue, as I was trying to juggle effort on the other two amps first.
I was finally able to finish it up in a nice enclosure over the weekend, and hooked it up. The sound of this amp was just about as musical as it could get - and this was under simple, non-critical listening, and just a result of my audible memory after listening to the other two amps (SymAsym and ICEpower) under the same conditions (my bench). IOW, this little guy really shined in just about every aspect of what there is to like about an amp. The mid-ranges and highs were spot on with a clarity and attack on every note yet still very smooth. The bass was as solid as could be given my small bench speakers. I was impressed. 🙂
Last night I was able to give it a better listen on my Energy RC 50s and I was not disappointed. One of my favorite CDs to test my amps and speakers is the excellent and well-produced recording of Volume II of the Nitty Gritty Dirt Band's 'Will the Circle be Unbroken' - circa 1989. While this genre of music may not appeal to the more refined tastes, it is a great test for the wide dynamic range of every component in your system. This particular recording includes a lot, if not all acoustic instruments - and they are very well recorded and reproduced on this CD. Another good test for an amp. In short, I was simple blown away by the musicality of the amp and the ease at which it executed every track. The sound stage was wide, and the entire sound spectrum was produced with detail, clarity and an energy you could feel coming through the speakers. My Energies faithfully reproduced every track from the solid but not overwhelming punch of the bass, to the very listenable sparkle of the highs, and the smooth sound of the vocals. The more and more I go back and listen to CD produced in the 80's I'm more amazed at the overall quality of the sound of many of them. Even some stuff that's been re-recorded and pressed onto new vinyl sounds great. Much of Pop music today just doesn't sound good IMHO and has not been that well produced. There are exceptions though.
Overall, this is a nice little amp and will find a home in one of my stereo rigs in the house. And even after a couple solid hours of listening to this CD, I never felt fatigued by the music. I still have a lot of listening to do, as I want the amp (or my ears) to break-in for awhile. And I want to include a wider selection of the music I enjoy.
BTW, this implementation of the LM4780 uses a linear PSU built into the PCB itself. All you have to do is hook up a tranny and you're good to go. I'm using the stock, recommended voltage of about 35VDC after rectification and filtering. Build pictures and additional impressions will follow.
Rick
Over the past several months, I've had 3 different amp projects in various stages (long, cold New England winter months. 🙂 ) going. Over the past couple of weeks I've finished up 2 of them, and the 3rd is waiting for its proper enclosure/chassis. The amps are; (1) SymAsym, (2) ICEpower, and (3) an LM4780. Due to my hectic schedule, I have not had the time to do any focused listening to any of them yet, over and above some burn-in with the little speakers (Auvio - RS closeout), I have at my bench for testing. However, I was surprised by the sound of he 4780 in particular.
I know the LM3886 chip-amp has somewhat of a cult-like following here on DIYAudio forums, but I was not aware until I heard with my own ears the sound it can produce. I used the twin brother of the LM3886, the LM4780 in my build - which is essentially the same chip in stereo packaging. I used the PA-03 (Pavel) version of the amp which is claimed to have an excellent layout and implementation of the chip. I kept pushing it to the rear of the line in my build queue, as I was trying to juggle effort on the other two amps first.
I was finally able to finish it up in a nice enclosure over the weekend, and hooked it up. The sound of this amp was just about as musical as it could get - and this was under simple, non-critical listening, and just a result of my audible memory after listening to the other two amps (SymAsym and ICEpower) under the same conditions (my bench). IOW, this little guy really shined in just about every aspect of what there is to like about an amp. The mid-ranges and highs were spot on with a clarity and attack on every note yet still very smooth. The bass was as solid as could be given my small bench speakers. I was impressed. 🙂
Last night I was able to give it a better listen on my Energy RC 50s and I was not disappointed. One of my favorite CDs to test my amps and speakers is the excellent and well-produced recording of Volume II of the Nitty Gritty Dirt Band's 'Will the Circle be Unbroken' - circa 1989. While this genre of music may not appeal to the more refined tastes, it is a great test for the wide dynamic range of every component in your system. This particular recording includes a lot, if not all acoustic instruments - and they are very well recorded and reproduced on this CD. Another good test for an amp. In short, I was simple blown away by the musicality of the amp and the ease at which it executed every track. The sound stage was wide, and the entire sound spectrum was produced with detail, clarity and an energy you could feel coming through the speakers. My Energies faithfully reproduced every track from the solid but not overwhelming punch of the bass, to the very listenable sparkle of the highs, and the smooth sound of the vocals. The more and more I go back and listen to CD produced in the 80's I'm more amazed at the overall quality of the sound of many of them. Even some stuff that's been re-recorded and pressed onto new vinyl sounds great. Much of Pop music today just doesn't sound good IMHO and has not been that well produced. There are exceptions though.
Overall, this is a nice little amp and will find a home in one of my stereo rigs in the house. And even after a couple solid hours of listening to this CD, I never felt fatigued by the music. I still have a lot of listening to do, as I want the amp (or my ears) to break-in for awhile. And I want to include a wider selection of the music I enjoy.
BTW, this implementation of the LM4780 uses a linear PSU built into the PCB itself. All you have to do is hook up a tranny and you're good to go. I'm using the stock, recommended voltage of about 35VDC after rectification and filtering. Build pictures and additional impressions will follow.
Rick
Pictures of LM4780 Build
As promised here are a few pictures of my recent LM4780 build. I am very pleased with the sound of this amplifier - or better yet, lack of sound of the amp. Very musical indeed, especially on acoustic instruments. You know, those 'old fashion' instruments before electric guitars and keyboards. 🙂 Kudos to Pavel Dudek for producing a fine implementation of this gainclone.
Rick
As promised here are a few pictures of my recent LM4780 build. I am very pleased with the sound of this amplifier - or better yet, lack of sound of the amp. Very musical indeed, especially on acoustic instruments. You know, those 'old fashion' instruments before electric guitars and keyboards. 🙂 Kudos to Pavel Dudek for producing a fine implementation of this gainclone.
Rick
Attachments
Thanks lyrics. This little amp is phenomenal. The more I listen, the more I like. The clarity across the entire range is exceptional IMO. With full-range speakers the bass is very tight and solid, with the mids and highs spot-on. It never becomes fatiguing to listen to.
Rick
Do you connect the +- and gnd from the SMPS to the AC and center tap locations of the PSU? This just effectively bypasses the rectifier and applies the onboard filter caps to the SMPS?
Thx.
Sorry for delayed reply.
Do you have schematic?
You are right in your assumption of connecting +/- of SMPS to bridge rectifier AC input (~) & "0" to C.T..
The torroidal Tranny will need to be disconnected.You may require 2 SMPS if dual voltage SMPS is unavailable. Do not use PC or laptop SMPS as the "-" is usualy connected to earth. You can verify this using DMM.
Alt. (but risky for accidental reverse supply connection) the "+" of SMPS(1) will go to "+" of positive rail capacitor , similarly" -" of SMPS(2) will go to "-" of negative rail capacitor. The center common connecting point between the two capacitors will be "0" or Ground.
Do you have schematic?
You are right in your assumption of connecting +/- of SMPS to bridge rectifier AC input (~) & "0" to C.T..
The torroidal Tranny will need to be disconnected.You may require 2 SMPS if dual voltage SMPS is unavailable. Do not use PC or laptop SMPS as the "-" is usualy connected to earth. You can verify this using DMM.
Alt. (but risky for accidental reverse supply connection) the "+" of SMPS(1) will go to "+" of positive rail capacitor , similarly" -" of SMPS(2) will go to "-" of negative rail capacitor. The center common connecting point between the two capacitors will be "0" or Ground.
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How does it compare to your SymAsym? I planned to build the SymAsym before but decided to stop the project due to lacking of time. Quite happy with the PA-03 now, would love to hear your thoughts regarding the two amps.
Hi rol,
To be honest, I'm enjoying the PA-03 so much I haven't taken the time to do any lengthy critical listening of the SymAsym. I did do a little this morning, using my favorite CD, and while the sound of each is very close, I would give a slight edge to the PA-03. I wouldn't say one is better than the other, just that there's a slight difference I can hear, but it's difficult to express subjectively.
The PA-03 is IMO a very musical amp. If I had to say anything, it would be there's a bit more crispness to the attach of notes. I will say, I'm very biased towards acoustic instruments whether it's a banjo, or a harp. I believe the real test of any amp and speaker system is how it performs with live acoustic instruments. Whether it's the high tingly notes of a mandolin, or upper registers of a piano, to the solid punch of the bass line from an upright bass. The PA-03 just seem to bring it all out as clear as bell -with little effort I might add.
To be fair, I do owe the SymAsym more listening and 'breaking-in' before rendering my final judgement, but by no means it is a mediocre performer. The two amps just sound a little different, yet that difference is very hard to articulate.
The real test may come when I compare it to my latest class D build. B&O's icePower amp modules - 250A. 🙂
Hope this helps.
Thanks for your thought. Great to hear they are very close. The PA03 is a lot easier to build, without any adjustment required. I did get some troubles with the relay, but managed to fix it. Mine is pretty much maxed out, using PRP resistors, CDE and Nichicon KA caps, metal-can opamps. I even machined a solid block of aluminum to use as a heatsink. The only thing I could imagine to upgrade is to use a better volume pot, currently using the bog standard Alps RK27. 
Thanks for your thought. Great to hear they are very close. The PA03 is a lot easier to build, without any adjustment required. I did get some troubles with the relay, but managed to fix it. Mine is pretty much maxed out, using PRP resistors, CDE and Nichicon KA caps, metal-can opamps. I even machined a solid block of aluminum to use as a heatsink. The only thing I could imagine to upgrade is to use a better volume pot, currently using the bog standard Alps RK27.
I will say the Sym is very easy to build (not sure what ver. you have.) I had the Black Beauties. It took me awhile, but not because it was difficult. Just because I take so much time! I also had other projects going. Too many! 🙂 I'm glad I built it because I said in another thread, it helped restore my confidence in building and adjusting a discrete amp. I was very happy with the result and sound. I'm going to make it a point to only use the Sym amp this week when I listen, to help it break-in a bit more. And break my ears in. 😀
Rick
Rick, nice build and probably good sounding amplifier. I try to finalize my first one after few year of ... silence
Can you tell me what push button was used for your amplifier? Look fantastic for me. Same volume control knob too.
Can you tell me what push button was used for your amplifier? Look fantastic for me. Same volume control knob too.
Check with this supplier on ebay; along
along1986090 on eBay
He used to carry them a few years back. Not sure if he still does. I don't see them listed in his ebay store. You might try contacting him directly and see if he can still get them. I did see the knob although it was knurled.
Rick
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