SKX15R Mod for more clean headroom

[Kludgemaster]

I have on old red knob Fender SKX15R practice amp with an 8 inch speaker.
It's rated at 32W on the back not sure why it is called 15R.
Anyway, it has plenty of volume for my purposes but as I turn the gain up, distortion kicks in.
I think that's by design but I like clean tones.

Is there any way to eliminate distortion from this amp without sacrificing volume?
It sounds OK with gain at about 3 or 4 and volume cranked.

You can see a picture of one here.
http://www.google.com/imgres?imgurl=http://www.geocities.jp/tachang_0606/CA310014.jpg&imgrefurl=http://www.geocities.jp/tachang_0606/Other.html&h=480&w=640&sz=93&tbnid=keLvj3wvHbse-M:&tbnh=95&tbnw=126&zoom=1&usg=__w7_aatd4CHYhK4IpVmcFarvkxHY=&docid=n1nM6-XVgzQ0UM&sa=X&ei=o-lYUu0rtazgA5WMgagN&ved=0CFcQ9QEwCA


Thanks in advance for any replies.

[Enzo]

The amp is not rated 32 watts, the amp USES 32 watts at its heaviest draw from the wall outlet.   15 watts is all you get.


I think you are just running into the limits of the amp.  The power supply voltages inside are the limiting factors, and once the signal levels reach those, there is no place left to go.

It's like bouncing on your bed, once you hit the ceiling, there is no real way to bounce any higher.

[Roly]

Is there any way to eliminate distortion from this amp without sacrificing volume?

Not really.  Once the output stage is limiting, that's all there is.  This is a fine little amp as far as it goes, and it sounds like you have taken it as far as it will go.

This style of amp, around 15  watts (which is actually quite a bit of power), physically small around a 10-inch or 12-inch speaker, look promising, but it's the "physically small" that does all the damage.

To compress a great deal into a few words; to get a big sound you need a big speaker, and when it comes to speaker enclosures - "there ain't no substitute for cubic feet".

About the only thing you can do with a finite amount of power is improve the speaker efficiency in dB_SPL per Watt, dB/W.  Some guitar cabs are no cracking 100dB/W, but the 90's are a reasonable target, and the speaker that is in there is likely to be only making high 80's at best, so there is considerable scope for improvement.

Simple test; try coupling the entire output of this amp to a 2x12 open back (like a Fender Twin style, find, borrow the use of).  With one important caveat(*) you're likely to find the amp transformed with a much bigger open voice, better bottom end, and a "bigger" sound.

(* the caveat is the amplifier basic frequency response.  In at least one case the amp is internally crippled in the bass so that it doesn't make the speaker fart in the tiny box, the fundamental resonance of which will be pushed right up in frequency to where there is no bass performance anyway.  (detail here)

[Cpt. FixIt]

It's been a while since I came across a Sidekick, but as far as I remember they all had clipping diodes somewhere in the signalchain.
I don't know if the attached schematic matches your particular amp, but if it did, I would remove diodes D3 to D6 and maybe change the value of R20 to compensate for the higher signal level.

regards,
Toby