OT: The fetzer valve blew up my amp! Questions about ruby.

[syndromet]

I breadboarded the fetzer valve last night, and hooked it up to my amp. I connected the output wire to the jack without the pot, and my amp made a weird cracking sound. I turned it off immediately. Now my amp hisses, and the volume is nowhere near what it used to be. It is a solid state amp. What could be wrong?

[wampcat1]

What kind of amp is it? When just plugging the guitar straight in is it still making these noises?
The Fetzer valve doesn't spit out *that* much signal, so I wouldn't think you would hurt your SS amp, though I'm just speculating.
Brian

[nelson]

I put a mosfet boost infront of a crappy 20w "soundking" bass amp last week.

It is now dead, blatty distortion at a really low volume.

Good news is, I now have an aluminium chassis to build a better bass head. Not worth repairing at all.

[Arn C.]

Syndromet,
   Follow the wiring from the input jack of your amp and look for fried components.  It "may" be the first component in line or maybe the first transistor or IC .  This will be the preamp section of your amp as you are still getting sound.  Give it a go!

Peace!
Arn C.

[syndromet]

The amp hisses, even if I turn all the knobs to zero. It's a cheap old Samic LA40R, but it's the only amp I have, and I can't afford a new one. I'll see if I can find some blown components. Thanx for all the help!

[syndromet]

I found a melted resistor in there!  Switched it, and the amp works again. It even stopped popping when I turn of the power.

[wampcat1]

I found a melted resistor in there!  Switched it, and the amp works again. It even stopped popping when I turn of the power.

While you have your amp apart you may want to tweak it a bit...you'll find that the SS amps tend to look like guitar pedal circuits in the preamp section so the same type of tweaks apply.

*make sure you check the psu caps to make sure they aren't storing DC while working on your amp. If in doubt, look through the archives either here or at ampage.org or geofex.com for how to discharge caps properly.

Take care,
Brian

[cx_deluxe]

Good to hear you've got it working again.  If you want another amp and can't afford to buy one, build a Ruby.  I built one and, for a practice amp, it sounds better and is way more useable than my 20 watt SS Peavey or my 15 watt SS Fender.  It's not fancy, it's still pretty loud (I can get the neighbours downstairs to complain), it's inexpensive, and it sounds great, espescially when you feed it with a Fetzer valve...

[Ge_Whiz]

I can't see how the Fetzer could cook a resistor, unless you hooked the 9V supply to the input of the amp by mistake. Even so...

[wampcat1]

I can't see how the Fetzer could cook a resistor, unless you hooked the 9V supply to the input of the amp by mistake. Even so...

I know what you mean... I was thinking maybe the resistor was getting ready to go anyway and maybe the booster put it over the edge. OR, maybe there wasn't an output cap on it? That would throw some DC on the input as well but it would buzz like a madman.

Brian

[syndromet]

The amp has been making a lot of noise lately, but it wasn't before plugging the fetzer in that it got realy bad. I guess the resistor was allready half gone...

I've been thinking of building a couple of ruby's or little gem's, since I use a preamp with stereo flanging, chorus and delay. How would you describe the differences between the two? how big is the differences between the Mk1 and Mk2 in sound and volume?? What speakers do you run them into?

Thanks a lot for the help. Both this forum and the DIY effect hobby is highly addictive. I didn't even need a fetzer valve, but since I'm waiting for parts for some other projects (the Norwegian customs takes ages), I had to build something from what I allready had. Guess I must have wired the fetzer up wrong yesterday, because today it sounds really good,without blowing my amp.

[cx_deluxe]

EVERYBODY needs a Fetzer...   

I haven't built the Little Gem.  IIRC the consensus is that the Mark II is superior, because of the input buffer.  If you've got a breadboard you can try just about anything... so build them all!  AS far as speakers go, people use all kinds of things, even 6x9s from their cars.  Once I tried a little 4" speaker I had lying around.  It worked ok, but then I tried the Ruby with the speaker in my Fender 15 and never looked back.  In fact I gutted that amp and stuck an EA tremolo> Ruby in the cabinet.  I'd say use a real speaker, but try whatever you have.  I will generally consider using anything old and/or free...

[syndromet]

EVERYBODY needs a Fetzer...   

I haven't built the Little Gem.  IIRC the consensus is that the Mark II is superior, because of the input buffer.  If you've got a breadboard you can try just about anything... so build them all!  AS far as speakers go, people use all kinds of things, even 6x9s from their cars.  Once I tried a little 4" speaker I had lying around.  It worked ok, but then I tried the Ruby with the speaker in my Fender 15 and never looked back.  In fact I gutted that amp and stuck an EA tremolo> Ruby in the cabinet.  I'd say use a real speaker, but try whatever you have.  I will generally consider using anything old and/or free...

The reason I don't need a Fetzer is because I'm running a Digitech GSP21 Pro, witch gates everything abowe a certain volume. This makes me have to run all my effects unboosted, and with volume turned way down. I guess a low-volume ruby is what I realy need, as I never turn the samick beyond 3 o'clock. If I do my girlfriend begs to stop practising my malmsteen and jason becker, and instead pick up the acoustic.

I'm wondering how loud the Ruby is before it starts breaking up? I don't want any clipping from my amp, as I have (almost) all the sounds needed on my pedalboard. Will the ruby sound good with any desent size speakers, even if they are not made for guitar? I'm planning a stereo ruby-head into two seperate 1*10 cabbinets. Do you guys beliwe this would be a good idea? How big is the differnce from guitar-speakers and hifi speakers?