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I have a low-fi amplifier (Niles si-245) that I am currently using with good success. The sound is pretty good for a $400 amplifier. I am considering upgrading a few internal parts to improve the sound. I would like to smooth out some harshness in the upper mids and treble.
To this end, I was going to change a capacitor(s) and also upgrade the fuses. I can handle the fuses and do the soldering for the caps. My only challenge is determine which caps I should change.
The photos below show the internals. The existing caps are as follows:
4 large black caps: Rubycon 50v 3300uf
2 large blue caps by the rear and middle: 25v 2200uf (not sure which brand)
I have not determined the size (uf) or brand of the multiple remaining smaller blue caps.
So, based upon what you know / see, which caps would you recommend changing? If you think I should change something else (as well or in lieu of), please let me know.
Regards!
Follow Ups:
Are you willing to accept the fact that you could destroy it? In my experience the mass produced amps have thin boards and traces. It is very easy to destroy a part of the board removing and re-installing components. I would never start this type project without a understanding of the circuit, a good variable heat range soldering station, and solder removal aids. You could start by replacing internal and external fuses. Install better input and output connectors and wire going to them. That might be enough to get you where you want to be. Good luck
Ill agree with Mike:
The board looks like one of those Compressed Cardboard types I had trouble with when working as a tech. As soon as you 'char' the board, you're either all-in or need to start rebuilding traces AFTER scraping all the 'char' off.
Real Glass Epoxy boards are far easier and forgiving to properly repair.
If you want to go ahead with this project, get the 'right stuff' in the form of the right desoldering tools, temp control iron, and stuff like solder wick and flux remover. You'll need it and for Pete's Sake, take your TIME.
Too much is never enough
Another thing to consider:
If you upgrade the cheap stock binding posts with Cardas CCBP S short billet copper binding posts, you may be surprised by how much upper midrange and treble glare is eliminated, along with a more detailed and firmer sounding gestalt from top to bottom:
http://cardas.com/ccbp_s.php
On sale for less than $50 per stereo pair, here:
http://www.douglasconnection.com/Cardas-Audio-CCBP-S-Binding-Posts-CACCBPS.htm
While you're at it, upgrade the stock nickel plated IEC inlet with a direct gold plated Furutech INLET(G) IEC inlet for further glare reduction benefits:
https://www.takefiveaudio.com/mall/shopexd.asp?id=1300
The upgraded parts may be removed and perhaps relocated to another amplifier you might purchase someday as a component upgrade.
my 2 cents
upped the value of the coupling caps to say - around 8800uf? Adding reserve power for improved dynamics??
I'm OBVIOUSLY no expert, but wouldn't a schematic be the most important component? This way you can trace out the audio path and see if you have any "lower grade" parts in the audio signal.
Don't forget about cheap resistors as well! Something about 1/4 watt resistors I never cared for in the signal path.
charles
As others have mentioned it's sort of hard to really be helpful since it's somewhat of a guess what circuits have which parts.
None the less... I notice several green squarish capacitors, I think one is C15. Depending on where they are in the circuit they can cause problems. Their technology is wrapped Mylar film and they have quite bad dielectric absorption and fairly high ESR. You might want to consider replacing them with stacked polypropylene or polycarbonate parts which should be around the same case size (but more spendy). Again, properly used they are fine and I'm probably responsible for hundreds of thousands of them in the field. However, for hi-fi...
Nothing else jumps right out. Have fun and don't modify anything that you aren't willing to scrap if things go awry!
Rick
and it would seem to me that way too many components would have to be changed to make the project sonically and financially worthwhile. If you must, at least get a schematic diagram to identify the coupling caps. I did not notice any film caps on the board. If your coupling caps are in fact electrolytic, then you may notice an improvement by replacing with films. But then again, maybe not. I would go with a much simpler design (tubed perhaps) to notice the benefits of component upgrades. Hope this helps. Cheers.
unless they're bad, you won't achieve anything.
Wait for a better amp.
.....it looks to me like they are using small electrolytics as output coupling caps, though the four large caps are certainly power supply. In which case, replacing the coupling caps or bypassing them with film caps would be a cheap and nice upgrade.Now that I look at it a little closer, there are two small green drop style caps at the very back of the board that appear to be film caps. The frequency response of the amp is from 10HZ which would be consistant with a small output coupling caps. My money is that these are the ones to change out. I don't think that there is enough real estate for oil caps without getting very, very creative, but you could probably squeeze a couple of Auricaps or Sonicaps in there for a very cheap upgrade.
Edits: 03/22/13 03/22/13 03/22/13
investing time and money to make marginal improvements in what the OP considers a "low end" amplifier makes sense.
as a learning experience or a training excercise.Better to learn on a cheaper amp than a megabuck component.
......for some of us, that's what makes it a hobby. And I have no idea if it will be an improvment at all, so I think that "marginal" is highly speculative in this context. My sense is that it would address the issues cited in the OP to some extent, but that too is speculative.
Exactly.
Don't get me wrong. I'm not one who thinks all amps sound the same or passive parts don't matter. With my Sound Lab stats, I purchased the "Hot Rod" option using higher performance components.
I do, however, put such improvements in context with what's getting modified.
.
The power supply is the heart and soul of the amp. If it isn't right nothing can be right. The caps in the power supply are critical to achieving optimum performance.Going from electrolytics to a better cap or even a better electrolytic can transform an amplifier.
That said, I don't think I would invest any time or money in a low end amp.
.
I'm glad you agree as to the context of my answer. :)
believe me. Simply save for a better amplifier.
Sorry to grave dig but I landed on this thread google searching for a schematic for the Niles SI-245 and found a some bad information so I thought I would set the record a little straighter.
The output of this amp is DC coupled. There are no coupling capacitors in series with the output.
Those blue caps at the upper right of the picture are in the (separate) power supply for the protection circuitry. They have no connection to the signal path.
In response to "viridian": Those small green caps close to the rear panel are in the Zobel network (see https://www.trueaudio.com/st_zobel.htm if not familiar). That 10 Hz lower frequency limitation is by design and also because the input stage is not DC coupled.
It's a fine amp for its purpose, but it is what it is, a well constructed, medium performance amp and changing a few caps or gold plating the power connector isn't going to change that.
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