SLO Channel Bleed

Mr. Willy

Mr. Willy

Well-known member
Amp gurus who know this stuff, is the channel bleed on the SLO actually part of its design? I seem to remember discussion about that at some point around these parts, but I’m not certain. If it is part of the design, what is the purpose? Or does it actually have a purpose?
 
It's just part of how it's designed. It doesn't have a purpose, as such. Most multi-channel amplifiers share significant parts of their preamps between the separate channels. It's very easy to set up switching so you nominally (on paper) switch one part out of the signal path, but it's able to bleed a bit into it on the other end.
 
Say if you have the clean channel set to crunch with the gain up, while you play on the distortion channel you can hear how it affects the tone of the amp, and not in a good way.. The original, older SLO's use LDR's for switching channels, and where they are placed in the circuit as well as how the LDR works never really shunts all signal to ground or turns fully on like a relay does.
 
jasonP said:
Say if you have the clean channel set to crunch with the gain up, while you play on the distortion channel you can hear how it affects the tone of the amp, and not in a good way.. The original, older SLO's use LDR's for switching channels, and where they are placed in the circuit as well as how the LDR works never really shunts all signal to ground or turns fully on like a relay does.
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Exactly, anybody that owns an SLO, play the lead channel with the rhythm channels volume and gain at zero, now, stay on the lead channel but bring your rhythm volume and gain up quite a bit With the crunch engaged, now play the lead channel again and you will hear the difference.
At least, the two that I owned over the years both suffered ‘bleed through’, the Lead ch sounded WAY better when the rhythm channel was set for ‘clean’…
 
You can also play with the channel volume on zero and bring up the volume for the other channel and hear the blead coming through. It's just wasted energy. The amp has to waste energy and dynamic range to produce that sound and the speakers have to work to do that as well. Not saying the SLO sounds bad or anything. But in terms of engineering... it's an inefficiency my OCD doesn't like.
 
SQUAREHEAD said:
Exactly, anybody that owns an SLO, play the lead channel with the rhythm channels volume and gain at zero, now, stay on the lead channel but bring your rhythm volume and gain up quite a bit With the crunch engaged, now play the lead channel again and you will hear the difference.
At least, the two that I owned over the years both suffered ‘bleed through’, the Lead ch sounded WAY better when the rhythm channel was set for ‘clean’…
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Wow. I did not know this. I’m going to try this experiment the next chance I get. I’ve been running mine on the crunch setting with the gain set fairly high. Thought the overdrive channel still sounded really good. Hmmm…I’ll report back later.
 
Mr. Willy said:
Wow. I did not know this. I’m going to try this experiment the next chance I get. I’ve been running mine on the crunch setting with the gain set fairly high. Thought the overdrive channel still sounded really good. Hmmm…I’ll report back later.
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Yeah Mr. Willy, try it, bro.
The lead channel is tighter and more pure, less congested when you set the rhythm ch Spanky clean.
 
SQUAREHEAD said:
Yeah Mr. Willy, try it, bro.
The lead channel is tighter and more pure, less congested when you set the rhythm ch Spanky clean.
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Ok. Tried it. It’s absolutely true. OD channel sounds noticeably better (clearer, slightly louder, more clarity, more sparkle) when Normal channel is set to clean. Dang. This changes how I run the amp now. I liked the crunch setting, and would use my volume for clean. Oh well. The OD channel cleans up very well, too. The clarity alone of the OD channel set this way is worth “loosing” the crunch setting. See, just when you thought you knew practically everything, setting-wise, of your amp. Thanks, guys!
 
Mr. Willy said:
Ok. Tried it. It’s absolutely true. OD channel sounds noticeably better (clearer, slightly louder, more clarity, more sparkle) when Normal channel is set to clean. Dang. This changes how I run the amp now. I liked the crunch setting, and would use my volume for clean. Oh well. The OD channel cleans up very well, too. The clarity alone of the OD channel set this way is worth “loosing” the crunch setting. See, just when you thought you knew practically everything, setting-wise, of your amp. Thanks, guys!
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Yep, it’s just ‘better’ with it set up that way bro👍
Like, once you experience it, it’s hard to go back. Impossible.
It breathes and responds, like you say, clearer, tighter and even a little bit louder.
Feels ‘right’ …Just better.
 
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SQUAREHEAD said:
Yep, it’s just ‘better’ with it set up that way bro👍
Like, once you experience it, it’s hard to go back. Impossible.
It breathes and responds, like you say, clearer, tighter and even a little bit louder.
Feels ‘right’ …Just better.
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Yeah, it’s clearly noticeable. And I was running bedroom volume, as low as it would go. I’d imagine the difference is even more pronounced the louder the amp is.
 
Mr. Willy said:
Yeah, it’s clearly noticeable. And I was running bedroom volume, as low as it would go. I’d imagine the difference is even more pronounced the louder the amp is.
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Oh yes, Sir Willy.
when you turn the amplifier up, the difference is way more noticeable, prevalent.
…you are going to be so pleased with the lead channel now!
 
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A lot of die-hard SLO fans over the years have refused to acknowledge this issue. It's pretty funny because it's so easy to recreate the problem and see just how it affects the sound/feel of the amp. You can always mod the amp to remove those LDRs though, like the new version.
 
FourT6and2 said:
A lot of die-hard SLO fans over the years have refused to acknowledge this issue. It's pretty funny because it's so easy to recreate the problem and see just how it affects the sound/feel of the amp. You can always mod the amp to remove those LDRs though, like the new version.
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I've owned an older original version SLO and have built one, 3 different ways for switching- stock with LDR's, relays in place of the LDR's and modified the circuit where the switching takes place with relays. The only real way to get rid of the channel bleed is to change where the switching is placed in the circuit and with relays. Just by putting relays in where LDR's are will only slightly help the bleed channel bleed...
 
jasonP said:
I've owned an older original version SLO and have built one, 3 different ways for switching- stock with LDR's, relays in place of the LDR's and modified the circuit where the switching takes place with relays. The only real way to get rid of the channel bleed is to change where the switching is placed in the circuit and with relays. Just by putting relays in where LDR's are will only slightly help the bleed channel bleed...
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Well yeah, there's more to it than just replacing the LDRs with relays; remove/replace. But it can be done. Supposedly the new SLO has fixed this issue (and moved the loop too?).
 
FourT6and2 said:
Well yeah, there's more to it than just replacing the LDRs with relays; remove/replace. But it can be done. Supposedly the new SLO has fixed this issue (and moved the loop too?).
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Yeah it would be interesting to know where they placed the relays in the circuit. I believe the loop is moved and looks like what the Decatone schematic is.
 
FourT6and2 said:
A lot of die-hard SLO fans over the years have refused to acknowledge this issue. It's pretty funny because it's so easy to recreate the problem and see just how it affects the sound/feel of the amp. You can always mod the amp to remove those LDRs though, like the new version.
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Who would do these mods? I’m no professional. I’ve had this amp for a long time now. I’m more open to modding it now than I used to be. I’d definitely have this issue fixed, though, if I could. I much prefer the crunch channel and actually used it a good bit. I would be curious also about the “scoop” mod on the crunch channel. Think that’s the DeMartini/SRV mod. I’d also have the loop modded to the new specs.
 
Mr. Willy said:
Who would do these mods? I’m no professional. I’ve had this amp for a long time now. I’m more open to modding it now than I used to be. I’d definitely have this issue fixed, though, if I could. I much prefer the crunch channel and actually used it a good bit. I would be curious also about the “scoop” mod on the crunch channel. Think that’s the DeMartini/SRV mod. I’d also have the loop modded to the new specs.
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I'm sure any amp tech worth their salt could do it
 
Mr. Willy said:
Who would do these mods? I’m no professional. I’ve had this amp for a long time now. I’m more open to modding it now than I used to be. I’d definitely have this issue fixed, though, if I could. I much prefer the crunch channel and actually used it a good bit. I would be curious also about the “scoop” mod on the crunch channel. Think that’s the DeMartini/SRV mod. I’d also have the loop modded to the new specs.
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I’d recommend having the following mods:

Have the clean channel default selected on the lead channel, and when the lead channel is not selected, have it default to whatever the front switch is set to - either clean or crunch.

I’d also install a tube buffered loop - location based on preference.
 
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