Help Fixing Ceriatone Effects Loop?

[ledvedder]

Hi guys,
I got a Ceriatone Chupacabra last week and although I love the amp, the effects loop is horrible. From my limited knowledge, it's a passive serial loop. So, as soon as I plug any pedal into it, the sound becomes muffled. See the video.



Ceriatone has said that a metro loop probably won't work. Something with the placement of the master volume? They keep pushing one of their external units (Klein-ulator), but I don't want to lug around another piece of equipment.

I'm attaching the schematic, if anyone would be kind enough to help me out.

 

[johan.b]

Ok. Seems they are tapping the loop between treble pot and p.i.. I see two problems (from my perspective, at least. )
Loop output impedance is too high for many pro/rack units. It wouldn't be a problem with stomp boxes. But for them, the high signal level is a problem instead.
The other is level will change with amp level and will be VERY high when playing at band level.
Do you have the same problem with stomp boxes and at bedroom level?
I would place the loop before the master volume instead, so you don't have to constantly check levels. You would also have to reduce and then at the "return" regain the level.
I think a Metro loop inserted between saturation switch and master volume pot would be a better solution than what's there now. ...but let's see what others say
J

 

[ledvedder]

Ok. Seems they are tapping the loop between treble pot and p.i.. I see two problems (from my perspective, at least. )
Loop output impedance is too high for many pro/rack units. It wouldn't be a problem with stomp boxes. But for them, the high signal level is a problem instead.
The other is level will change with amp level and will be VERY high when playing at band level.
Do you have the same problem with stomp boxes and at bedroom level?
I would place the loop before the master volume instead, so you don't have to constantly check levels. You would also have to reduce and then at the "return" regain the level.
I think a Metro loop inserted between saturation switch and master volume pot would be a better solution than what's there now. ...but let's see what others say
J

I only use stomp boxes, and I'm having the problem at any volume.

 

[paul-e-mann]

Hi guys,
I got a Ceriatone Chupacabra last week and although I love the amp, the effects loop is horrible. From my limited knowledge, it's a passive serial loop. So, as soon as I plug any pedal into it, the sound becomes muffled. See the video.



Ceriatone has said that a metro loop probably won't work. Something with the placement of the master volume? They keep pushing one of their external units (Klein-ulator), but I don't want to lug around another piece of equipment.

I'm attaching the schematic, if anyone would be kind enough to help me out.

Ask this same question to Metropoulis and send them the schematic, friendly knowledgeable people who will have an accurate answer where to put their loop.

Can you explain to me what the "pussy trimmer" really is? Is it a resonance knob or something?

 

[ledvedder]

Ask this same question to Metropoulis and send them the schematic, friendly knowledgeable people who will have an accurate answer where to put their loop.

Can you explain to me what the "pussy trimmer" really is? Is it a resonance knob or something?

Yep, I have posted there. That forum seems kind of dead these days.

The "pussy trimmer" seems to be just a knob (1 meg) on the back of the amp that reduces the max amount of gain that comes out of v1.

 

[paul-e-mann]

Yep, I have posted there. That forum seems kind of dead these days.

The "pussy trimmer" seems to be just a knob (1 meg) on the back of the amp that reduces the max amount of gain that comes out of v1.

But cant you just do that with the gain knob on the front?

What I meant was contact the Metropoulis sales dept., I asked them a question about their effects loop kit and they got back to me the next day.

 

[ledvedder]

But cant you just do that with the gain knob on the front?

What I meant was contact the Metropoulis sales dept., I asked them a question about their effects loop kit and they got back to me the next day.

This is Ceriatone's explanation for the pussy trimmer - "However, if you are a straight-to-amp player, we have installed a trimmer aptly named “PUSSY TRIMMER”. The amp is sent from our test bench with it at its maximum setting (out of circuit). If this background gain wash and tendency to feedback bothers you, you can turn down this control to reign in the amplifier‟s “gainiac” nature. The PUSSY TRIMMER is currently offered inside the amp (The 1M trim pot near V2 tube)."

I definitely helps control feedback and allows more flexibility in the gain settings. You can make the gain less hairy and smoother, if that makes sense.

 

[neikeel]

Yep, I have posted there. That forum seems kind of dead these days.

The "pussy trimmer" seems to be just a knob (1 meg) on the back of the amp that reduces the max amount of gain that comes out of v1.

Different questions.
Some similar answers

 

[ledvedder]

Different questions.
Some similar answers

Huh?

 

[okgb]

I installed the granger fx loop in a friend's 800 and after the treble control it just didn't work , levels were bad and you couldn't get unity gain & bypass, we changed it to after the master and the levels were better, still a noticeable tonal change but the levels were usable so he left it there!

 

[mickeydg5]

There is no drive or return buffering for the loop. That sucks big time! Look at any decent loop and you will see buffering on both sides of the loop.

Yes, you may want the Master Volume after the loop.

 

[SirArcsAlot]

On my plexi amps I tap off the treble pot for a send signal . I use a pot to trim down the outgoing signal and then an op amp running at 48v split rail then runs the signal back up to the desired level to push the power amp via a potentiometer on the feedback loop of the op amp.

The reason you use a 48v supply is so the signal that you buffer back out will not become distorted by surpassing the supply rail voltage. The signal voltage coming off your treble pot will be around 25vac.

 

[ledvedder]

On my plexi amps I tap off the treble pot for a send signal . I use a pot to trim down the outgoing signal and then an op amp running at 48v split rail then runs the signal back up to the desired level to push the power amp via a potentiometer on the feedback loop of the op amp.

The reason you use a 48v supply is so the signal that you buffer back out will not become distorted by surpassing the supply rail voltage. The signal voltage coming off your treble pot will be around 25vac.

Does the Metro zero loss loop take care of this? I have one on the way.

 

[johan.b]

I never used a metro loop. But i think that's the whole point of that particular product. Being discrete circuit, it can deal with much bigger signals than your typical opamp based loops, such as the one in Marshall reissiues and that's why it gets so much praise.
J

 

[SirArcsAlot]

If I am no mistaken the metro loop runs off an 18v supply which is not adequate

 

[dslman]

Strange they would build such a nice sounding amp , w/ the loop sucking so much volume and tone.

 

[jman271]

I stalled a Granger fx loop and it works fine. It has trim pots for the send (a reduction trim only), and then a 6+ db trim return so if you experience some loss, you can make it back up. It gets B+ power from the board and then it is wired into the circuit in the same places as the Q and E on the schematic..If has an on/off switch and works good enough for me. Here is a clip of the amp with the loop and reverb added, pretty clean and chunky.

I start switching to the dly and stuff about 2 min into the clip

 

[ledvedder]

I stalled a Granger fx loop and it works fine. It has trim pots for the send (a reduction trim only), and then a 6+ db trim return so if you experience some loss, you can make it back up. It gets B+ power from the board and then it is wired into the circuit in the same places as the Q and E on the schematic..If has an on/off switch and works good enough for me. Here is a clip of the amp with the loop and reverb added, pretty clean and chunky.

I start switching to the dly and stuff about 2 min into the clip

Damn, that sounds nice! What are your settings on the amp? What guitar and pickups?

 

[jman271]

I made the guitar, ( I will try to post a pic?), the pickup is a seymour duncan 78' custom shop (low output like 9k), the amp settings are normal bas/mid treb, etc,,it is a 50 watt plexi Ceriatone JMP with diff mods I did on the inside with caps and resistors etc I really think the 25 watt greenbacks helped alot tho!
The guitar is a 2 piece basswood, rock maple neck, took me a yr to make bc I was so nervous about making a mistake lol, I learned alot about how to make it by watching videos and stuff.

 

[ledvedder]

I made the guitar, ( I will try to post a pic?), the pickup is a seymour duncan 78' custom shop (low output like 9k), the amp settings are normal bas/mid treb, etc,,it is a 50 watt plexi Ceriatone JMP with diff mods I did on the inside with caps and resistors etc I really think the 25 watt greenbacks helped alot tho!
The guitar is a 2 piece basswood, rock maple neck, took me a yr to make bc I was so nervous about making a mistake lol, I learned alot about how to make it by watching videos and stuff.

Nice! I either want to build a Ceriatone JMP50 or JTM45 next.

I also built a Franky replica. It's Ash with an EVH Frankenstein humbucker.