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SLO 100 clean tone?

7/3/2004 2:43 PM
Terry Shipman
SLO 100 clean tone?
There are many comments about the OD tone of an SLO's and I am thinking of building one, but little is ever mentioned about the clean channel.  
Opinions anybody?  
Terry Shipman
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7/3/2004 6:45 PM
Joe L

Put it in Crunch mode, set your guitar on ~7 and turn the preamp volume of the clean channel such that you are still clean unless you really strum it hard. If you have a good sounding guitar, it will sound great. Turn the guitar up for Plexi type leads and only use the lead channel for the wild stuff. You can even use a distortion pedal on the crunch setting for a more retro type distortion.  
Good luck!  
..Joe L
7/6/2004 5:43 AM

Terry, my experience is that using an EQ (10-band, in my case) effect, and a HotPlate both make the 'clean' channel come alive (Bill Sundt, at Soldano, suggested the EQ). At lower volumes, these measures are particularly important, it seems to me. These things add 'bottom' and 'sparkle' (to my ear). Recently, though I'm still using the HotPlate, I've substituted a Mesa Boogie V-Twin pedal into the clean channel (with the channel set absolutely clean) to provide 'clean' (on bypass) and 'crunch', and 'more crunch' (on the two pedal settings). My opinion is that the stock SLO clean channel is thin, and more so at lower volumes. (I play into a Mesa Boogie Rectifier closed-back cabinet with dual V30's). Opinions (at least on Harmony Central) vary pretty wildly on this topic. Some swear by the clean SLO channel - some revile it. As for the OD channel (once again this is my opinion of course) I only have the Mesa Recto series to compare against (having owned one) - but the Soldano is noticably more distinct (and so in my opinion, better) at high gain settings than the Mesa. Another way to look at this is that the Soldano is a lead guitar player's amp. Since I'm a rhythm player, I've done things to fill out the mix. If it does nothing else - the 'stock' SLO 100's clean and OD channels cut. Visit Harmony Central and read the SLO reviews for yourself. Like mine, they're totally subjective, but at least you can get a number of opinions - some of which provide good food for thought.
7/12/2004 11:19 AM
Terry Shipman
Re: SLO 100 clean tone - any mods?
Thanks for the useful replies. Are there any popular mods or ideas for mods to modify the clean channel inside the preamp itself that would "thicken" or otherwise improve its apparent shortcomings?  
7/12/2004 11:39 AM
Dominik SRV Mod? List of known Mods
Hi Terry,  
I am looking into a List of Mods as well, which I plan to do to my clone.  
Here is what I know:  
1. Warren Haynes Mod:  
There seems to be a confusion about this mod. Some people claim, that the bright cap across the OD Control is switched out by the mod, others say (somebody from Soldano acutally) say the Mod is the bright cap, since Warren Haynes uses only little gain and thus the sound gets a bit dull when dialing the OD only a bit. This is what I have found in my "mongrel" amp where I have a SLO OD section as well. I would say the Warren Haynes Mod is the bright cap.  
2. Depth Mod:  
NFB mod which lessens the NFB on the low frequencies (comparable to the Presence knob, only affecting low freqs.)  
3. SRV Mod:  
This one is either just different values of the Tonestack caps (normal SLO is: 470pF, 0.022uF, 0.022 uF, 47k Slope) to Fender values (250pF, 01, uF, 0.047 uF) or something done to the Clean channel.  
4. 39k to 10k cathode resistor mod on OD:  
This lowers the gain of the third stage in the OD, gives slightly less compressed sounds.  
5. Half Power:  
This Mod simply siwtches out two power amp tubes of the Quad. You will get a different sound, since the prim. impedance ratio will change and the remaining tubes are biased hotter. This does not (IMHO) change the preceived output too much.  
Here are some things I want to address in my clone:  
I heard about the shortcomings of the Effects-Loop.  
One possibility could be to move the whole loop: Use the 4 tube preamp and use the 5th tube for a Dumbleator style Loop. Or keep the 5 tube preamp, but use the FX IN and OUT jacks to slave in a Dumbleatorstyle looper (Flex-Looper for example). I will definitely try this first.  
So, if anybody knows some more, I would be glad to hear about them! :-)  
7/13/2004 1:02 PM
I think the switch from a 39k cathode resistor to a 10k actually increases the gain but there is less compression and distortion.  
I have a Dumbleator loop in my amp that is similar to a SLO (sort of). I changed the Send circuit a little bit though (see the Send circuit in a Dual Rectifier, very similar to that). My loop works really well. Five preamp tubes total including PI.  
My little bit of experience with the SLO clean channel was that the 39k resistor that is switched in when you put it on Clean mode castrates the tone. I took it out and ended up adding some series resistance (bypassed with a cap, 470k/470p IIRC) after the 500k gain pot and then adding another resistor (220k IIRC) to ground right before the second grid. Adjust bright cap across gain pot to taste (~100pF works for me). I "think" this decreases the AC loading on the output of V1a which seems really high with that 39k resistor in there. If I want it clean, I have to run the gain pot really low but it is spanky and sparkly. If I crank the master it will break into harmonic feedback while still clean. However, this changes the Crunch mode but I set the "Lead" channel to a good rhythm tone and then use some built-in boost options to get into Lead territory. Even the rhythm tone will sing and feedback at very low volumes.
7/13/2004 4:35 PM
Chris - CMW amps
Rick E. ?
Hi Dominik  
Lots of cloners do use the resonance-circuit from the Peavey 5150.  
Lowering the 39k cathodeR to 10k will up the gain.  
Rick Erickson did post some time ago about the SRV-mod he did see , afaik it was a T-filter ( to cut mids ) on the clean/crunch-channel.  
Hope this helps,  

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