Bare Knuckle Pickups Forum

Forum Ringside => Tech => Topic started by: Lukie on July 29, 2009, 10:53:40 PM

Title: bleeding amp channels
Post by: Lukie on July 29, 2009, 10:53:40 PM
I have a new amp with a weird "feature/fault". If you turn up the gain on the distortion channel, you can hear it faintly through the clean channel. You can even set the clean channel gain to zero, and you only get the bleeding through signal from the distortion channel. It was battered around a bit in transport so I am not sure if its a factory error or damaged in transit. :(

Has anyone experienced this before??
Title: Re: bleeding amp channels
Post by: HTH AMPS on July 30, 2009, 01:16:20 AM
It's a 'feature' on the Soldano SLO100, and thats a VERY expensive amp.  Consider it a boutique tweak  :lol:

Seriously though, its nothing to worry about except if it gets in the way of your playing.
Title: Re: bleeding amp channels
Post by: jpfamps on July 30, 2009, 01:10:41 PM
I have a new amp with a weird "feature/fault". If you turn up the gain on the distortion channel, you can hear it faintly through the clean channel. You can even set the clean channel gain to zero, and you only get the bleeding through signal from the distortion channel. It was battered around a bit in transport so I am not sure if its a factory error or damaged in transit. :(

Has anyone experienced this before??

This is quite common, and perfectly normal.

It is either caused by capacitive cross talk between the two channels and/ or by feed through from imperfect switching elements.

In general use this should not be a problem, and "curing" it on most amps could be tiresome.

In an SLO100, as mentioned above, this is actually a "feature" of the channel switching. Essentially the clean channel is never switched off, so when the gain channel is on then the clean channel is swamped by the hotter signal.

Also the two channels are out of phase, so there will be some signal cancellation. I don't know if this contributes much to the SLO100 sound or not. When we've experimented with this type of circuit we've not incorporated this "feature".
Title: Re: bleeding amp channels
Post by: HTH AMPS on July 30, 2009, 02:58:03 PM
I think the out of phase clean channel on the SLO100 was an accident that they happened to like.  Thats my take on it anyway.  Like JPF, when I've played with the same circuit I've not incorporated this 'feature' either.
Title: Re: bleeding amp channels
Post by: Lukie on August 02, 2009, 01:41:58 PM
thanks guys, but this amp is more like the gain channel is never turned off and can be heard faintly on the clean channel. I am going to get it checked out at the nearest dealer/repairer.
Title: Re: bleeding amp channels
Post by: jpfamps on August 03, 2009, 01:49:30 PM
thanks guys, but this amp is more like the gain channel is never turned off and can be heard faintly on the clean channel. I am going to get it checked out at the nearest dealer/repairer.

Sounds like it might be a fault, and if the amps new it would be worth getting it checked out as it could be a simple fault in the switching.

The gain channel is always more likely to bleed through due to the larger signals.

By the way, and this applies to all posters in the tech forum, IT'S A LOT EASIER TO HELP IF YOU STATE WHAT THE AMP IS!!!!



Title: Re: bleeding amp channels
Post by: Lukie on August 09, 2009, 08:31:23 PM
its a blackstar series one 45
Title: Re: bleeding amp channels
Post by: jpfamps on August 10, 2009, 07:36:09 PM
its a blackstar series one 45

I've not had my hand on one of these (probably a good sign as I generally only see amps when they have broken), and haven't seen the schematic/ layout, so I can't comment on whether this is an inherent feature of the amp.

It might be worth trying to get in touch with other owners.
Title: Re: bleeding amp channels
Post by: Lukie on August 11, 2009, 09:22:31 PM
The guy in the shop says he will replace the amp! Will report back if the new amp has the same fault, but it would be a shame, as i really like the crunch distortion channel on this
Title: Re: bleeding amp channels
Post by: FELINEGUITARS on August 11, 2009, 11:40:21 PM
I think the out of phase clean channel on the SLO100 was an accident that they happened to like. 

Some people don't care for the thinning out that is caused by the out of phase channel being mixed in

That is why they made the Avenger apparently - no clean channel - all tone , gain and fat sound
Title: Re: bleeding amp channels
Post by: jpfamps on August 12, 2009, 05:04:54 PM
I think the out of phase clean channel on the SLO100 was an accident that they happened to like. 

Some people don't care for the thinning out that is caused by the out of phase channel being mixed in

That is why they made the Avenger apparently - no clean channel - all tone , gain and fat sound

I've always been a bit puzzled by the out of phase clean channel issue in the SLO-100. I've always assumed it was a bit of a botch.

The SLO-100 uses LDRs which are probably the worst device to use for switching.

With two LDRs (as in the SLO-100) you could "mute" both channels using shunt switching, so in theory, ie assuming that the LDRs are perfect switches (!!?), you swich channels without the out of phase issue. My guess, from playing around with this type of circuit, is that with this arrangement the very high gain of the lead channel would cause bleed through into the clean channel with  this type of arrangement.

I guess this was deemed worse than the mixing of the lead and out of phase clean channel, so the two LDRs are arranged to switch the lead channel off. The "problem" could be solved by using more LDRs, or better switching devices.

Incidentally, although I am not really into high gain amps, I think that this a great sounding circuit.
Title: Re: bleeding amp channels
Post by: HTH AMPS on August 13, 2009, 10:06:28 PM
Its an even better sounding circuit if you build the OD channel straight up with no channel switching.

I've messed around with building it without the two DC-coupled CF stages and you get a less compressed tone, slightly less distortion, but a rawer overall tone.  The two DC-coupled CF stages really seem to smooth it out.  When I mess with this again, I'd probably use a single 12AX7 for the send/return and use an AC-coupled CF to drive the send and a simple gain stage for the return recovery stage.  I've done this in other amps and liked the tone this setup gives, alot.

Title: Re: bleeding amp channels
Post by: Lukie on October 20, 2009, 07:49:18 PM
I got my shiny new replacement S1-45 amp, and it sounds even better than the last one, and no channel bleeding now! Im very pleased, if i had a mike (and could play better) i would post some clips thinly veiled as riff raff and cold sweat clips  :D