Ice Pick Root Cause?

Im not sure if its a low end type of thing. Probably more of a voicing issue. My cheapo Crate Stealth GT50 is impossible to make sound icepicky-trebly but not icepick. Then again my Rivera Chubster was pretty "icepicky" with certain speakers in it. My Palomino V32(399$) isnt icepicky at all--again with the right speaker in it. I think its a combination of voicing and the speaker mated to the amp not the cost involved. Bob

 

I don't think you can nail it down to one thing. I've spent a lot of time voicing amps and not that I would want to but I believe I could build an "ice picky" amp in a number of ways.

 

It's because you let a country player try your amp.Now there's no cure.

It's the voicing of the amp that causes it.The teble cap,the coupling cap choices,the tone stack,the cathode bypass caps on the preamp tubes.All dictate how much high end gets through.

 

Failure to use the tone control on the guitar.

 

I only have experiences with Fenders.

I noticed a massive improvement on ice-picky tones when I replace the 250pf treble tone cap from the original Ceramic to Silver Mica.

In fact, I actually like the tone of ceramics in all other pf value places, but that one 250pf cap is silver mica every time.

Now, to be honest, I've heard ceramics have a tendency to have a lot of "Bad" caps, so theres a good chance my experiences are with faulty cermic caps, but everytime i've replaced them with a silver mica, its improved.

Other areas to note are the Coupling Caps throughout the amp. If these are ceramic, then getting a Polyester or Polypropolyne cap in its place (I use Orange Drop PS series myself) will also improve the overall treble response.

Lastly, sorry to say, the guitar has a massive effect on this. I've had guitars that make an amp sound warm and smooth and i've had others that make it unbearibly icepicky... and it has nothing to do with the tone knob.

In the end, Ice-pick to the ears can be solved in every amp, imo. It just takes the time and effort to track down the culprit. I have no proof, but I have a feeling the overall icepick tone comes from leaky capacitors somewhere in the amps. Got any gut shots of your amp in question?

 

Don't forget speakers too.

 

i posted in the other thread

 

I had very picky DRRI, even with the bright cap cut it was harsh in the upper registers. I went silver mica for the 250 treble cap, but I saw most difference by slighty changing the value of the slope resisitor. After I experimented with some coupling caps (and trying some things that didn't work so well too) I was able to dial this DRRI into a very sweet sounding (I used Orange Drops 716p's).

 

Up front, try a 5751 or 12ay7 as the first triode and at the end, use a beam blocker. Of course, Albert Collins seemed to like the it that way...stop playing a tele with a capo.

 

An amp does not have to have ceramic disc caps to not be icepicky.I use silver mica in all my builds and they are not icepicky at all.There is something else causing this.
The basics need to be adressed here.One,a DRRI is not icepicky by nature,so it must be something amiss in the circuit to cause this.
Check things like output tube bias,drifted or incorrect resistors,bad grounds especially in the tonestack area and underfiltering in the power supply.Orange drop coupling caps are brighter than most so changing to orange drops is not a cure.

 

Hey Rick1114,
Which resistor is the one you refer to as the slope resistor?

Thanks!

P.

 

Actually my suggestion was to NOT use ceramic disk caps. They ARE the cause of a good amount of ice-picky tones. I think its a combination of leakage and inherent grainyness of ceramic caps that create the problem.

In my suggestion, though, its important to note i like the tone of ceramics in certain spots, but the treble tone cap and coupling caps are not one of them.

I have just recently taken a super reverb from a friend that had a metalic highend shrapnell and the first thing I did was replace the 250pf tone cap with a silver mica and it immediatly tamed down considerably. Do you have any gut shots of the amp in question?

 

Bright caps on certain amps / reissue amps. Certain speakers, certain pickups ...... easy to isolate and fix usually.

 

amp voicing and speaker choice...It's that simple..

 

I read once somewhere on an internet far far away that harshness or the ice pick effect stemmed from too much high order harmonics.

 

I changed the slope resitor (R18) to 90k from 100k - helped a lot. Also changed the mids resisitor to 10k, but that's more for preference really. Then did the PI coupling caps and it was like a tranformed amp.

 

Rick,
By PI coupling caps do you mean the ones that couple the output of the PI to the 200k output stage input resistors (i.e., the output tubes grid resistors) ?

What values did you use there that resulted in less "icepick?"