Dumble clone (Ceritone) OTS50

[dbharris]

for instance my digital scope doesn't do a good job for this task

What scope are you using that can't handle that?

Hey Josh, I am sure it's user error...I have a Hantek DSO5102P. I can always use it pretty easily, but this particular task I could not figure out a way to have the signal at both cathodes displayed in a manner that showed the changes to each introduced by adjusting the PI trimmer. And as far as I can tell, I can only use the "measure" function for one channel at a time.

[JMPGuitars]

Hey Josh, I am sure it's user error...I have a Hantek DSO5102P. I can always use it pretty easily, but this particular task I could not figure out a way to have the signal at both cathodes displayed in a manner that showed the changes to each introduced by adjusting the PI trimmer. And as far as I can tell, I can only use the "measure" function for one channel at a time.

Oh, sorry. No offense, but almost everybody I've heard of that has a Hantek scope says...don't buy a Hantek scope. I've never had a Hantek, but that's how I feel about Rigol. I'm guessing it's more useful than the haters claim.

You're probably right about the math function being limited to 1 channel, but why do you need a math function? What are using the math function to track?

[dbharris]

Hey Josh, I am sure it's user error...I have a Hantek DSO5102P. I can always use it pretty easily, but this particular task I could not figure out a way to have the signal at both cathodes displayed in a manner that showed the changes to each introduced by adjusting the PI trimmer. And as far as I can tell, I can only use the "measure" function for one channel at a time.

Oh, sorry. No offense, but almost everybody I've heard of that has a Hantek scope says...don't buy a Hantek scope. I've never had a Hantek, but that's how I feel about Rigol. I'm guessing it's more useful than the haters claim.

You're probably right about the math function being limited to 1 channel, but why do you need a math function? What are using the math function to track?

It's not a very user friendly scope. Buy once cry once and all, but I did cheap out on this purchase and it shows. The goal is to get the amplitude of both signals to be exactly the same.

That's why using the DMM also works because the signals are obviously opposite at the those cathodes when you measure across them (and not with respect to ground). By setting to mv resolution, when the DMM reads 0 they are matched. Too far in either direction and it will swing positive or negative.

[JMPGuitars]

It's not a very user friendly scope. Buy once cry once and all, but I did cheap out on this purchase and it shows. The goal is to get the amplitude of both signals to be exactly the same.

That's why using the DMM also works because the signals are obviously opposite at the those cathodes when you measure across them (and not with respect to ground). By setting to mv resolution, when the DMM reads 0 they are matched. Too far in either direction and it will swing positive or negative.

Amplitude isn't a Math function, it's a function of Measure. The manual doesn't make it clear if you can measure from multiple channels or not, but I assume you should be able to. Page 33 covers measurements: http://www.hantek.com/Product/5000P/DSO5000P_Manual.pdf

It does say you can display 8 measurements at once, so it's possible you can select the channels for each, but you have to experiment with that.

On my scope, I select the channel, then select the measurement type. Here's a quick example I setup:

SDS2504XP.png

Thanks,
Josh

[dbharris]

It's not a very user friendly scope. Buy once cry once and all, but I did cheap out on this purchase and it shows. The goal is to get the amplitude of both signals to be exactly the same.

That's why using the DMM also works because the signals are obviously opposite at the those cathodes when you measure across them (and not with respect to ground). By setting to mv resolution, when the DMM reads 0 they are matched. Too far in either direction and it will swing positive or negative.

Amplitude isn't a Math function, it's a function of Measure. The manual doesn't make it clear if you can measure from multiple channels or not, but I assume you should be able to. Page 33 covers measurements: http://www.hantek.com/Product/5000P/DSO5000P_Manual.pdf

It does say you can display 8 measurements at once, so it's possible you can select the channels for each, but you have to experiment with that.

On my scope, I select the channel, then select the measurement type. Here's a quick example I setup:
SDS2504XP.png

Thanks,
Josh

Thanks, I will give that a try next time I have a chassis out of the headcab!

[foreverstrung]

https://youtu.be/kCOt-gdoLzQ?si=8K92t_gnLZebJWQU

Sound check

[dbharris]

https://youtu.be/kCOt-gdoLzQ?si=8K92t_gnLZebJWQU

Sound check

Glad you got this up and running! What speaker are you playing through? It sounded good, this was just clean then OD, no PAB or Mid Boost?

[foreverstrung]

Glad you got this up and running! What speaker are you playing through? It sounded good, this was just clean then OD, no PAB or Mid Boost?

Yes. I didn't even really go to far into the OD or mid boost at all. My main objective with this short clip was just to show how silent it was. I never really get the true output or sound recording with an Iphone 14

The speaker is a WGS Blackhawk. It's actually the speaker for my TMB w/Reverb build. I've got a 16ohms Celestion Cream laying around I was going to use in the speaker cabinet I'm going to build for this. Not sure how it'll sound. Love this Blackhawk, but I've got the pricey Cream speaker just laying around. I don't really want to spend $300 on another speaker if I don't have too.
Thoughts?

[foreverstrung]

Not so fast!
I'm having some problems with the OD. It appears the preamp is the only dirt i'm getting. The OD trim pot and main pot are doing nothing. Presence is having little to no influence on the OD channel either.Trouble shooting now.
Likely pulling out the scope

[foreverstrung]

So for some reason, (human error), I've dropped the OD signal all together. Went thru the voltage chart again and all my voltages look good. Put a scope on it and am getting no signal at the OD channel. Replaced V2 tube, still no change. I'm posting a pic of the schematic and then a point on the diagram that IDK what it means. Any help is appreciated.

IMG_0607.jpg

What does this mean?

IMG_0606.jpg

The rest of it, tho there are some modifications/additions

[JMPGuitars]

It's drawn as two switches and a pot. The two switches could actually be one DPDT switch, but I'm not familiar with the amp. I assume it is a DPDT switch.

[dbharris]

That's the channel switching relay. But it is drawn a little weird on the schematic and it looks like they omitted the PAB relay on the schematic. As long as you followed the layout and used the correct relays, it should be fine. It looks like there is an under board jumper on the Channel relay board. Does your PAB relay work correctly? You can also use the manual/pedal switches on the back to test that way.

Probably good to pull out the scope and start signal tracing.

In terms of the speakers, I bet the cream will sound good. G12-65 and EVM 12L are the favorites.

[foreverstrung]

That's the channel switching relay. But it is drawn a little weird on the schematic and it looks like they omitted the PAB relay on the schematic. As long as you followed the layout and used the correct relays, it should be fine. It looks like there is an under board jumper on the Channel relay board. Does your PAB relay work correctly? You can also use the manual/pedal switches on the back to test that way.

Nik at Ceritone told me that the layout has some things that are not in the schematic and to stick to the layout.
I did catch that underboard jumper yes. It's clear on the layout.
My schematic reading skills have improved since last year, but I'm still real new.
The PAB does work very well. I've got the OD working now too, but not like it did originally or as it should. OD is only working when the footswitch toggle is engaged. (set for pedal), without the pedal even being connected. With the pedal connected, they both work as they should. PAB and OD
This amp has been like whack a mole tho with little issues. Now the rock/jazz toggle does nothing nor does the tone stack. I get sine waves through the treble, mid and bass, but the treble, (which is directly connected to the rock/jazz toggle), shows no increase increasing/decreasing the sine signal. Mid and Bass do show sine increase/decrease adjusting the pot, but when the guitar is plugged in, all 3 knobs of the tone stack don't do squat that I can hear and as I said, the rock/jazz switch does nothing..........When I started fiddling with the completed amp, they all worked. Now that I've been dicking with it, IDK what i've done.
Yet!
It's the journey, right?
With the volume on 2, OD and PAD about halfway and my guitar on 6/7, this amp shakes the house. Sounds awesome. Full of relatively clean grit. But I know it'll even be better once I get this tone stack figured out.
Attached layout

Overtone-Special layout pdf.pdf

[dbharris]

That's the channel switching relay. But it is drawn a little weird on the schematic and it looks like they omitted the PAB relay on the schematic. As long as you followed the layout and used the correct relays, it should be fine. It looks like there is an under board jumper on the Channel relay board. Does your PAB relay work correctly? You can also use the manual/pedal switches on the back to test that way.

Nik at Ceritone told me that the layout has some things that are not in the schematic and to stick to the layout.
I did catch that underboard jumper yes. It's clear on the layout.
My schematic reading skills have improved since last year, but I'm still real new.
The PAB does work very well. I've got the OD working now too, but not like it did originally or as it should. OD is only working when the footswitch toggle is engaged. (set for pedal), without the pedal even being connected. With the pedal connected, they both work as they should. PAB and OD
This amp has been like whack a mole tho with little issues. Now the rock/jazz toggle does nothing nor does the tone stack. I get sine waves through the treble, mid and bass, but the treble, (which is directly connected to the rock/jazz toggle), shows no increase increasing/decreasing the sine signal. Mid and Bass do show sine increase/decrease adjusting the pot, but when the guitar is plugged in, all 3 knobs of the tone stack don't do squat that I can hear and as I said, the rock/jazz switch does nothing..........When I started fiddling with the completed amp, they all worked. Now that I've been dicking with it, IDK what i've done.
Yet!
It's the journey, right?
With the volume on 2, OD and PAD about halfway and my guitar on 6/7, this amp shakes the house. Sounds awesome. Full of relatively clean grit. But I know it'll even be better once I get this tone stack figured out.
Attached layout
Overtone-Special layout pdf.pdf

When you are tracing the signal through the tone stack, make sure PAB is off. Is your rock jazz switch a 3 position? If so, PAB is also activated in the middle position.

You may want to chopstick solder joints and the shielded cables. Some shielded wire is more finicky than others and it can be easy to overheat when soldering causing an intermittent connection between the shield and conductor.

One you get all the bugs ironed out, I would highly recommend you build a dumbleator buffered effects loop. Even if you don't want to run effects in the loop, it will allow you to crank the amp for the sweet spot in tone while keeping the output volume wherever you want. It works way better than an attenuator since these amps are really about preamp distortion.

[foreverstrung]

When you are tracing the signal through the tone stack, make sure PAB is off. Is your rock jazz switch a 3 position? If so, PAB is also activated in the middle position.

You may want to chopstick solder joints and the shielded cables. Some shielded wire is more finicky than others and it can be easy to overheat when soldering causing an intermittent connection between the shield and conductor.



One you get all the bugs ironed out, I would highly recommend you build a dumbleator buffered effects loop. Even if you don't want to run effects in the loop, it will allow you to crank the amp for the sweet spot in tone while keeping the output volume wherever you want. It works way better than an attenuator since these amps are really about preamp distortion.

This was totally just user error. Tone stack is fine. The PAB being activated was/is the issue. It's only a 2 position switch, but when the PAB is activated, there is no tone stack.
I ordered a "Dumbleator". Chassis and parts anyways. I'll put it together. Install it with my new head.....
I'm really enjoying getting to know this amp. Lots of variations.
I'll post pics of the Dumbleator and then the cabinet fabrication after on this thread.

[foreverstrung]

One you get all the bugs ironed out, I would highly recommend you build a dumbleator buffered effects loop. Even if you don't want to run effects in the loop, it will allow you to crank the amp for the sweet spot in tone while keeping the output volume wherever you want. It works way better than an attenuator since these amps are really about preamp distortion.

So I got the Components for a "Dumblator" and put it together. Amazing how this amp sounds. I've been toying with it for weeks now. The Dumblator really puts an extra shine on the tone. Still experimenting with diff pedals and the many variants of this amp. The ONLY thing left to dial in is that I've got some unwanted noise n the FET channel. When I'm playing, it can't be heard, but quiet, with the guitar plugged in and volume at 0, it still sounds like there are some gremlins in there playing hockey or something.......I've done the chopstick thing a few times. Went thru and tidy'd up all my solder joints. What I'm not 100% clear on is how the sound moves thru this part of the circuit. When I put a scope on it, the sine waves look great.
Anyways, love this amp. Eventually I'll get going on the cabinet. I've ordered everything for it. It will be a 1 of a kind
attachment=0]dumblator 1.jpg[/attachment] i

[Bieworm]

Might be tube related?

[dbharris]

One you get all the bugs ironed out, I would highly recommend you build a dumbleator buffered effects loop. Even if you don't want to run effects in the loop, it will allow you to crank the amp for the sweet spot in tone while keeping the output volume wherever you want. It works way better than an attenuator since these amps are really about preamp distortion.

So I got the Components for a "Dumblator" and put it together. Amazing how this amp sounds. I've been toying with it for weeks now. The Dumblator really puts an extra shine on the tone. Still experimenting with diff pedals and the many variants of this amp. The ONLY thing left to dial in is that I've got some unwanted noise n the FET channel. When I'm playing, it can't be heard, but quiet, with the guitar plugged in and volume at 0, it still sounds like there are some gremlins in there playing hockey or something.......I've done the chopstick thing a few times. Went thru and tidy'd up all my solder joints. What I'm not 100% clear on is how the sound moves thru this part of the circuit. When I put a scope on it, the sine waves look great.
Anyways, love this amp. Eventually I'll get going on the cabinet. I've ordered everything for it. It will be a 1 of a kind
attachment=0]dumblator 1.jpg[/attachment] i

Glad you've got it up and running! How would you describe the noise?

What are your voltages for the FET? There is 1 bias resistor for the FET that you usually have to tweak once everything else with the amp is in order.

When you use this input, your guitar signal goes through the FET before any tubes. It is like a boost pedal in front of the amp, but built in.

Depending how you set the trimmer, you can adjust the voltage gain. 10db is sort of standard.

This type of amp won't be totally silent in all operating modes. For the normal input, clean channel should have no hum or hiss, overdrive channel may have a little hiss depending how you have it setup. With the FET input there will definitely be hiss on the overdrive channel when you are not playing maybe a little in the clean channel too.

With the loop and amp not closed up and in their cabinets things should quiet down a little bit too.

-Dan

[foreverstrung]

This type of amp won't be totally silent in all operating modes. For the normal input, clean channel should have no hum or hiss, overdrive channel may have a little hiss depending how you have it setup. With the FET input there will definitely be hiss on the overdrive channel when you are not playing maybe a little in the clean channel too.

The amps hums and hiss's are just as you've described. Overdrive is amazing on this amp. It does have the light hiss. The normal channel with the PAB active or not, is very quiet.....The FET noise is kind of like it's picking up an outside signal of some sort. Kind of. It's not overwhelming, but it's a Bee in my bonnet. The setting on the FET channel trem pot/resistor you spoke of, I've been playing with. I turn it down, the noise is less, obviously, but still present. I really prefer the Nor channel, but I'm reluctant to move to the cabinet stage till I figure this out......I will check the voltage and get back with you on that....AND, I'm reluctant to have this project end. This by far has been my favorite amp. To build and play.......not that I'm that great at either, I sure find a lot of joy in both.

[dbharris]

This type of amp won't be totally silent in all operating modes. For the normal input, clean channel should have no hum or hiss, overdrive channel may have a little hiss depending how you have it setup. With the FET input there will definitely be hiss on the overdrive channel when you are not playing maybe a little in the clean channel too.

The amps hums and hiss's are just as you've described. Overdrive is amazing on this amp. It does have the light hiss. The normal channel with the PAB active or not, is very quiet.....The FET noise is kind of like it's picking up an outside signal of some sort. Kind of. It's not overwhelming, but it's a Bee in my bonnet. The setting on the FET channel trem pot/resistor you spoke of, I've been playing with. I turn it down, the noise is less, obviously, but still present. I really prefer the Nor channel, but I'm reluctant to move to the cabinet stage till I figure this out......I will check the voltage and get back with you on that....AND, I'm reluctant to have this project end. This by far has been my favorite amp. To build and play.......not that I'm that great at either, I sure find a lot of joy in both.

Yes, whoever coined the term "talent in a box" in reference to these amps really nailed it! I really love the FET input as an additional color option. Some people do not like it though...

A couple of things to try:
Wrap a piece of cardboard in aluminum foil and set it on top of the chassis. This may shield whatever signal the FET is picking up.

Do you have LED lights in the same room or circuit? Try turning them off...this makes a huge difference in my house for the hiss background noise stuff.

Double check resistance between ground points on the FET board and it's star near the input jacks.

Unrelated to the FET, for the loop you may want to back the send pot down to between 10 and 11 o'clock. You can of course run this as high as you want before it clips your loop effects (pedals) input. The return, back down to about 2 o'clock. And of course the output pot becomes your global volume/master control. This may let you turn the master volume on the amp up higher. Between 11 and 1 o'clock are good. This will hit the cathode follower/send triode of the loop harder and give you some nice natural feeling compression.

-Dan