A Wondrous Adventure: SLO Clone Build (Now with Clips)

[xXDaveyJonesXx]

Marked for progress updates. Have fun, man!

 

[xXDaveyJonesXx]

Oh, and excellent move on the Iron.

 

[duesentrieb]

Hi Mike,

just 2 things:
Please don't use black Silver Micas (although even Bogner uses them) - I've had (others as well) dozens of failed black (btw a hint Larry once gave me) - the brown Micas are fine for high volt. applications though. They will fail in positions where you have high voltage, they are fine for signal. Alternative: Murata.

Please try a lower resistance for the input resistor. The 68k will let the amp hiss like the Niagara falls when in overdrive mode and idle (guitar vol down). Use a (much lower) value here. And to be on the safe side: add a 22nF cap before it (input jack, 1M ground, 22nF --> input resistor) - thats a safety cap (most designs using it today for a reason) will keep the DC off your guitar in case you should forget a ground somewhere or any other high voltage failure.

Olaf

 

[stefvorcide]

nice projet! I,ll stay tuned in here!

Where did you buy the kit, on metro amps ??

It's been a few years I'm planning to buy an amp..

 

[FourT6and2]

Hi Mike,

just 2 things:
Please don't use black Silver Micas (although even Bogner uses them) - I've had (others as well) dozens of failed black (btw a hint Larry once gave me) - the brown Micas are fine for high volt. applications though. They will fail in positions where you have high voltage, they are fine for signal. Alternative: Murata.

Please try a lower resistance for the input resistor. The 68k will let the amp hiss like the Niagara falls when in overdrive mode and idle (guitar vol down). Use a (much lower) value here. And to be on the safe side: add a 22nF cap before it (input jack, 1M ground, 22nF --> input resistor) - thats a safety cap (most designs using it today for a reason) will keep the DC off your guitar in case you should forget a ground somewhere or any other high voltage failure.

Olaf

Thanks Olaf! For the preamp, I'm using those blue dipped/molded ceramic disk caps. I believe they are the same ones Soldano uses.

I was planning on trying something like 33k for the input grid resister. For the 22nF cap, is it in series with this resister, attached to the shielded cable to V1?

This is a different cap than what you describe, right? I was told I could go as low as 33K without having to add a cap between the grid and anode like it describes here: http://www.valvewizard.co.uk/gridstopper.html

"The grid stopper can be made smaller in value if the effective value of the input capacitance is made proportionately larger. This can be done by placing a capacitor between the anode and grid of the valve. This capacitor applies negative feedback of very high frequencies to the grid, and appears in parallel with the Miller capacitance, so its value is also multiplied by the gain of the stage, due to the Miller effect."

nice projet! I,ll stay tuned in here!

Where did you buy the kit, on metro amps ??

It's been a few years I'm planning to buy an amp..

I don't think Metro sells SLO kits/parts. For a SLO build, you need to source a lot of parts yourself. Or try C3, as he can source mostly everything for you.

 

[duesentrieb]

Will send you a mail, Mike. Two different things here.

 

[fretout]

That looks pretty ambitious and very inspirational! I'll be wishing you a straight, smooth project, and I look forward to seeing your SLO Clone take shape!

 

[FourT6and2]

Will send you a mail, Mike. Two different things here.

Thanks, I think I understand:

In the SLO, there is already a 1M Resistor on the input jack. So I would:

1. Add a 100pF Ceramic Disk cap in parallel with this 1M Resistor.
2. Add a 22nF/630V cap in series with the Input Grid Resistor to V1. Probably right on the jack, before the conductor of the shielded cable.
3. Lower the value of the Input Grid Resistor.

Correct?

 

[mjtripper]

Will send you a mail, Mike. Two different things here.

Thanks, I think I understand:

In the SLO, there is already a 1M Resistor on the input jack. So I would:

1. Add a 100pF Ceramic Disk cap in parallel with this 1M Resistor.
2. Add a 22nF/630V cap in series with the Input Grid Resistor to V1. Probably right on the jack, before the conductor of the shielded cable.
3. Lower the value of the Input Grid Resistor.

Correct?

You can use a 33k resistor without a cap to ground, or for even less hiss use a 10k with something like a 620pf between the grid and cathode, right on the tube socket. Works great on high gain amps.

 

[FourT6and2]

Will send you a mail, Mike. Two different things here.

Thanks, I think I understand:

In the SLO, there is already a 1M Resistor on the input jack. So I would:

1. Add a 100pF Ceramic Disk cap in parallel with this 1M Resistor.
2. Add a 22nF/630V cap in series with the Input Grid Resistor to V1. Probably right on the jack, before the conductor of the shielded cable.
3. Lower the value of the Input Grid Resistor.

Correct?

You can use a 33k resistor without a cap to ground, or for even less hiss use a 10k with something like a 620pf between the grid and cathode, right on the tube socket. Works great on high gain amps.

I'll be experimenting once I build it stock first. What's the difference between using a 1K input grid resistor with the 100pF cap on the jack, vs. a 10K grid with something like a 620pF cap between the grid and cathode?

Most of the parts should be here this Wednesday, can't wait! But I'm out of town for a wedding all weekend. So I might have to wait to start diving in until next week.

 

[BSRIAudio]

SLO builds are fun! Here is one I finished up a few years ago:

 

[FourT6and2]

SLO builds are fun! Here is one I finished up a few years ago:

Awesome! You have high(er) res photos I can look at? And any shots of the loop jacks, slave, output jack wiring? Hard to see, but what ground scheme did you use—output jacks chassis-grounded or grounded to the power tube sockets?

 

[bwgintegra]

What size choke are you using for your build and radial or axial on the power board?

 

[BSRIAudio]

SLO builds are fun! Here is one I finished up a few years ago:

Awesome! You have high(er) res photos I can look at? And any shots of the loop jacks, slave, output jack wiring? Hard to see, but what ground scheme did you use—output jacks chassis-grounded or grounded to the power tube sockets?

Chassis grounded. I dont have any higher res photos on hand but I just studied pictures of a real SLO and replicated all those wiring bits and pieces in mine. There are loads of photos on the SLOClone forum.

 

[FourT6and2]

What size choke are you using for your build and radial or axial on the power board?

Choke is 5H. Radial caps. I'll post photos and such once everything gets here.

SLO builds are fun! Here is one I finished up a few years ago:

Awesome! You have high(er) res photos I can look at? And any shots of the loop jacks, slave, output jack wiring? Hard to see, but what ground scheme did you use—output jacks chassis-grounded or grounded to the power tube sockets?

Chassis grounded. I dont have any higher res photos on hand but I just studied pictures of a real SLO and replicated all those wiring bits and pieces in mine. There are loads of photos on the SLOClone forum.

Real SLOs have done it both ways. I was just curious what you did. I've been through most of the photos on the SLOClone Forum. Great resource.

 

[FourT6and2]

Transformers arrived today. The mailman complained about the weight of the box. So I guess that means they're beefy enough.

I think I might degrease the outside and paint the covers with some high-temp automotive paint (flat black), just to clean 'em up a bit.

 

[Death by Uberschall]

Transformers arrived today. The mailman complained about the weight of the box. So I guess that means they're beefy enough.

I think I might degrease the outside and paint the covers with some high-temp automotive paint (flat black), just to clean 'em up a bit.

Chrome plate the bell covers, that's the way the originals were made.

 

[FourT6and2]

Transformers arrived today. The mailman complained about the weight of the box. So I guess that means they're beefy enough.

I think I might degrease the outside and paint the covers with some high-temp automotive paint (flat black), just to clean 'em up a bit.

Chrome plate the bell covers, that's the way the originals were made.

Nah, too much work. Nobody's going to see them anyway. I like the matte look of the trannies that Rob from C3 did with his build. Clean. Plus I already put two coats of flat black on!

 

[FourT6and2]

This is how they look after degreasing and lightly sanding with 400 grit. You'd be surprised how much dirt, oil, and grease are on transformers straight from the manufacturer. They probably do that so the iron doesn't rust.

 

[bwgintegra]

Transformers arrived today. The mailman complained about the weight of the box. So I guess that means they're beefy enough.

I think I might degrease the outside and paint the covers with some high-temp automotive paint (flat black), just to clean 'em up a bit.

Are these the O'netics transformers and choke?