How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

[bullittstang]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

I read through that forum post (previously and again today), and as per the norm, half say it's the same while the other half say it's different. It gets so confusing sometimes. I can't find the referenced LME49720 in a DIP-8 format anyway (digikey, mouser), so it's a moot point. I went ahead and got some NE5532's some OPA2134's to try out and see what I think/hear. We will see in a couple weeks when the parts get here. My previous AMP 100 has the LM4562's, so I might be able to do a direct A/B comparison.

[tyger23]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

I'm freaking out right now.... The LM4562 in DIP has been EOL'd. EXPLETIVE, EXPLETIVE, EXPLETIVE. I have no idea what I'll be using now. It's still available in SOIC, so maybe I'll buy some of those SOIC to DIP adapters.

https://www.sparkfun.com/products/13655

The NE5532 is a good, budget option. It would be the safe choice, but it does NOT sound as good as the 4562. The OPA2134 is a very good op-amp, but it's JFET and I simply have never liked how they sounded when compared to my bipolar LM4562. Many people feel exactly the opposite as me (they prefer the OPA2134). Your mileage may vary. To each his own. Typically, you would want to design the circuits around a JFET and a BIPOLAR differently, but they can often drop in place of one another.

This might provide some other options:

http://nwavguy.blogspot.com/2011/08/op-amp-measurements.html

[johngalt47]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

While we are on this topic...https://m.youtube.com/watch?v=u8NZZP_DLWM

[dcibel]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

I'll consider myself lucky to have a couple DIP LM4562 in the drawer still. There's lots and lots of op-amps in the world to choose from. The NE5532 is the "industry standard" cheap op-amp used in lots and lots and lots of electronics, from inexpensive AVR's to high dollar pro-audio gear. It has a very "neutral" sound which is likely why its used everywhere, it doesn't really add any character of its own, but its not the ulitmate in hifi capability. The LM4562 is excellent and affordable, IMO a better option than some high dollar instrumentation parts some people use. I'd still want to use it everywhere I can, so get a handfull of the SOIC-DIP adapters and have fun! Or if you have money to burn the metal can version is still available.

[pfrakes]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

If a different brand is OK, Mouser has some through-hole 4562's:

http://www.mouser.com/ProductDetail/NJR/NJM4562D/?qs=sGAEpiMZZMuUbyQTl9BuV%252bWkQ1cVapN4EMkM9xjg2Ko%3d

In case that link doesn't work, the part number is NJM4562D.

I like the NE5532's myself.

[r1c0rtez]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

Glad I found this forum post ,I went and bought a broken amp 100 for cheap because someone cut the power cord and being someone new to the electronic repair scene I figured this would be a good place to start, so far there's no bulging caps or broken/burnt components but I replaced the cord and the fuse blew immediately with a wisp of smoke near the bottom side of the heatsink....I am planning to upload photos later ,but any initial thoughts on what is wrong with the amp?

[JRT]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

I'm freaking out right now.... The LM4562 in DIP has been EOL'd. EXPLETIVE, EXPLETIVE, EXPLETIVE...

Similar expletives, regarding loss of future availability. LM4562 may be available in SOIC, but some other magic beans such as the LME49990 are going away. Yesterday I ordered 100 of the LME49990 from Newark, and am considering ordering some of the others that are at lifetime buy, soon obsolete.

LM3875 is another one that is going away. That was the chip Junji Kimura used in the 47 Labs Gaincard Model 4706 after being pleased with the easy cheap results from a benchtop test amplifier he had cobbled together using the same chip. LM3875 has 3dB lower noise floor compared to LM3886.

A lot of the 44V operational amplifiers are going away.

I was disappointed back when TI killed National Semiconductor's LME49871. None were made after TI took over, and that was very shortly after National had brought that to market. I had wanted to use the LME49871 (44V current feedback) as a gainstage ahead of the LME49610 (44V unity gain buffer) inside the feedback loop of an LME49990 (36V). LME49871 could swing in excess of 36Vpp, was clean, and the speed would have been useful inside the feedback loop of the LME49990.

[drewdigs]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

Update: finally sat down and did most of the mods on Saturday night; finished up putting the heatsink back on, reconnecting speaker outputs and buttoned it all back up last night. I haven't had a chance to put a signal through it yet. It is sitting in my office right now powered up; I'll leave it this way for the day just to break it in thermally but not seeing any puff of magic smoke so far, so feeling pretty good.

I opted not to do the input-switching mod I had asked tyger23 about earlier; there would have been a clearance issue mounting a switch to the front panel that would have required drilling both the front panel and the chassis sub-panel right behind it. The sub-panel is not detachable from the rest of the chassis, and I felt like I would have had to yank the transformer, the switches and the speaker terminals out so I didn't throw some metal shavings into some unknown corner of the chassis and have it short something out later. I also really needed a better drill press; I had borrowed one I wanted to use for this project but it was in pretty rough shape and I couldn't get the belt changed to a lower speed. I could have mounted it to the back panel but it would have been inconvenient to have it there for my purposes. In the end I decided I'd see how the improved relay worked and let it be. Really, for the amount of input switching I need to do, I just need to spring for a true integrated.

I opted to get the heatsink off to get access to the resistors that are near the amp chips and didn't have too many issues putting all that back together either. It is extremely messy though so if you do decide to get that heatsink off, prepare a plastic bag or something to hold the heatsink and keep the compound off your hands/clothes/parts. That crap gets everywhere I swear. Be careful with the mica insulators; I would suggest grabbing them with a small tweezers so you don't crack them trying to lift them off/onto the heatsink. The compound can be cleaned off the insulator, the heatsink and the chips pretty easily with IPA. I used Arctic Silver on reassembly for compound but Dow Corning 340 looked like what was in there stock, so you could use that too.

In light of reading on the thread here that the LM4562 is EOL'd, I opted to put sockets in for the op amp locations so they could be swapped if I ever felt like it. Probably not necessary but I had them laying around, so why not.

By the way, was anyone else's board covered in some black heat-shrink liquidy goop crap? What the hell were they thinking using that stuff? I suppose they never expected anyone to want to remove some of that wiring but my goodness was that stuff awful to get up and out. Hit it with a heat gun and lightly scrape with a small screwdriver and it should pull up from the board.

I'll do some listening later and post some thoughts. Overall though this was a really fun project and worth a Saturday and $40 in parts for sure.

[drewdigs]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

It's pretty crazy how much of a difference this has made. I would describe it as being more opened up now. I haven't measured anything but I'd guess frequency response is better; I'm just going off what I'm hearing. The improvement in balance left and right is shocking. This is really impressive, its kinda hard to believe! Thank you tyger23 for taking your time to put this together. If you were on the fence don't be, it's totally worth it.

[tyger23]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

Glad you're enjoying it!

[bullittstang]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

Can someone tell me if this is an acceptable power supply capacitor substitution?
http://www.mouser.com/Search/Product...LPX682M050C7P3
It's a Cornell Dubilier SLPX series and I've never heard of them. I originally ordered a Nichicon LKG version, but it's was 30mm diameter and I can't get it to fit. The Panasonic ECO I used on the last upgrade is now NLA and can't find a suitable replacement from Panasonic that will fit.
The other option is a Vishay 256-PMG-SI series. http://www.mouser.com/ProductDetail/...PCnf4Bkg%3d%3d
Thoughts on which is a better choice?

[tyger23]

Re: How to turn your AudioSource AMP 100 into a real amp. (Paying it forward)

I used those Vishay caps on the Pyle amp mods. They'll do just fine.

[drewdigs]

Don't know if anyone else has seen this but AudioSource is releasing a V2 of the AMP-100. I've seen some pictures and it looks like they have added tone controls for treble/bass to the rear panel, a trigger in/out, as well as some minor cosmetic changes. Still no "true" input 1/input 2 switching, which drives me crazy! And why mount the tone controls in the back??? I guess they still consider this amp a "contractor" amp but it would have been great to have some knobs to twiddle on the front panel. It would be interesting to see what kind of changes were made to the boards and whether tyger23's mods are still applicable. Perhaps they implemented some of his improvements? We can only hope...

[marstedt]

Looking at picking up a few of these. Any comments on alternative opamps for the out-of-stock lm4562? I think there's still some stock on the NJM4562.

[tyger23]

OK, I would probably get the LM4562 in the Soic 8 package (which is still available), and then buy some SOIC to DIP adapters.

http://www.digikey.com/product-detail/en/aries-electronics/LCQT-SOIC8-8/A880AR-ND/4754588

If you don't feel comfortable with soldering those, then I would probably choose the NE5532 or the NJM4562.