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SLO-100 mods

5/28/2000 5:54 PM
Jeff Nickoloff
SLO-100 mods
I want to take some of the edge  
{fizzy highs} out of the lead channel. I already have the Warren Haynes mod. This amp has 6l6s. My other Soldano uses 5881 and it's much warmer and doesn't have that fizzy top which I don't like. I wonder if this is a factor. Anyone have suggestions or ideas?  
5/28/2000 6:27 PM

I was thinking of a few things that would solve this problem in my clone and I came up with two solutions. This is one:  
Use a trimpot, say 1M and wire it up as a rheostat on the return grid of your fx-loop. (mount it on the socket)  
Then all you have to do is turn it until you find your favourite setting and then forget about it.  
This makes a really cool tone control only using the "Miller effect". I have sucessfully installed this another of my amps.  
Good luck!  
5/29/2000 5:18 PM
Jeff Nickoloff

Thanks, I'll suggest this to my tech. But this sounds like it will effect both channels once it's set. Also, I was wondering if the power tubes could be suspect. It sounds more like a preamp thing though. To get rid of the fizz I have to keep the highs and mids down low and this makes the tone too dark and muffled.  
5/30/2000 5:44 AM

It will effect both channels, thatīs for sure.  
I like my sound a bit "mid-ish". I do not like those razor sharp highs some amps produce.  
I installed the pot I mentioned in my modified Marshall and it made all the difference.  
I suggest you try the other alternatives mentioned aswell. They are all pretty non-invasive and completly reversable.  
Good luck!  
6/1/2000 3:40 AM

Hi Jeff,  
I built the Soldano SLO 100 into a 50 watt clone and yes there is a slight fizz on top. I have compared my SLO to another real Soldano that had that same fizz also. After reading Ray Ivers reply , his mods sounds most logical in taming the fizz. Im gonna try his suggestion and Ill post after I do to let you know the outcome. Im also going to reinstall the 5881s back into my amp to see if that makes any changes in sound also.  
6/1/2000 9:50 PM

"To get rid of the fizz I have to keep the highs and mids down low and this makes the tone too dark and muffled."
Try replacing the 220K plate resistors with 100K's. This will eliminate the "fizz" and the tone will sound far better in my opinion.  
5/29/2000 6:51 PM
Ray Ivers

At first, I thought that what you wanted would be very simple to do, but after looking at the print from Steve Ahola's Blue Guitar site, I see that it is not; in fact, it looks like Mike Soldano's already tried to get rid of the fizz, evidently without much success (.001 uF cap across the 100K plate resistor of V2b). This is a pretty large value of cap for this purpose, and would be maybe too effective if used on the final overdrive stage, but unfortunately there's V3b yet to go, which is evidently the stage mostly responsible for the sizzle. Because of the master setups, it's just not as simple as putting a 20 to 100 pF cap across the 1M 'OD master' control - it will affect both channels. I'm not familiar with the Warren Haynes mod - I hope it will not render everything I've suggested below useless to you.  
Here's what I would do: try getting the overdrive channel sounding the way you want it by putting a small-value cap (maybe 50 to 150 pF to start) across the 220K plate load resistor of V3b (or, as mentioned above, you could put a 20 to 100 pF cap across the 1M 'OD master' control, which may also make the whole amp quieter) - this should be VERY effective in cutting the fizz. Then, try to regain the treble lost in the Normal channel by putting a bypass cap or series resistor/cap combination across the 2.2K cathode resistor of V1a. If you were using the Normal channel for a clean sound, this should work fine; if you were overdriving the Normal channel, you may or may not be 100 percent satisfied with the Normal channel's sound after this mod (you may like it better!).  
Ray Ivers  
R.A.G.E. Electronics

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