Tone stack

[Reeltarded]

Oh yeah.. I'm schooled.. I'm a Dumble nub.

[Lynxtrap]

It's called a skyliner tonestack, usually in 4th gen ... .

Just to avoid misunderstandings:
Most 4th generation ODS amps without a later "Skyline" modification: "classic" tone stack.

Additional info: https://ampgarage.com/forum/viewtopic.p ... 16#p237429

Cheers,

Max

Ehh...just to be clear, is the one I'm trying to make a "Skyliner"? What is the difference between "Skyliner" and "classic" in terms of values and components?
I find it a bit hard getting a fast overview of circuits looking at layouts. I prefer schematics, but that doesn't seem to be the case with you D and TW people

[erwin_ve]

Ehh...just to be clear, is the one I'm trying to make a "Skyliner"? What is the difference between "Skyliner" and "classic" in terms of values and components?
I find it a bit hard getting a fast overview of circuits looking at layouts. I prefer schematics, but that doesn't seem to be the case with you D and TW people

Yes yours is a Skyliner. It's all in the Dumble files section of this forum, you can find a wealth of layouts and schematics. In this topic:https://ampgarage.com/forum/viewtopic.php?f=5&t=5719 there are 2 schematics. The 124 reverse engineered version with Skyliner tonestack and the 1984 version with classic tonestack.
Happy Xmas!
Greetings from your unschooled Dumble nub

[Lynxtrap]

Yes yours is a Skyliner. It's all in the Dumble files section of this forum, you can find a wealth of layouts and schematics. In this topic:https://ampgarage.com/forum/viewtopic.php?f=5&t=5719 there are 2 schematics. The 124 reverse engineered version with Skyliner tonestack and the 1984 version with classic tonestack.
Happy Xmas!
Greetings from your unschooled Dumble nub

Thanks! I was (at least half) joking. I know I haven't been digging deep enough in the files section.
I've just noted that searching for D- and TW-circuits (not just in this forum) often seems to lead to layouts more than schematics. Which is of course great for building.

Might be useful to have the classic to compare to in this case. I saw that someone thought the Skyliner sounds boomy in comparison, which makes me a bit worried. Boomyness is one of the problems with my current Fendery circuit.
I got some components yesterday so I might put it on the bench tonight and see how it works out.

[Reeltarded]

People use all kinds of speakers and cabs and instruments and Skyliner is not boomy.

lol

With mid boost it's weird, but boomy? Neh. I can imagine a person coming from shallower slopes setting controls with their eyes making it be boomy. Like getting a complaint from a client that the Twins you sent sound like crap and you pop the cases to find the eq controls on ten.

I don't care what style of music they played; that was a punk band.

[Lynxtrap]

People use all kinds of speakers and cabs and instruments and Skyliner is not boomy.

lol

With mid boost it's weird, but boomy? Neh. I can imagine a person coming from shallower slopes setting controls with their eyes making it be boomy. Like getting a complaint from a client that the Twins you sent sound like crap and you pop the cases to find the eq controls on ten.

I don't care what style of music they played; that was a punk band.

Actually, it was the guy who posted the schematics of #124 in the thread that ervin_ve linked to

But yes, everything effects everything.
The tone stack in the, basically, Fender channel in my preamp build was boomy even with the bass knob at zero. And the mid control is all over the place.

I have noted these tendencies playing guitar through Fender amps, and you can see it in the Duncan TSC, but to this extent...
Playing bass and running the preamp to a dedicated bass power amp and speaker is a different deal than playing a Tele through a Twin Reverb.

Made me realize that the standard Fender tone stack is actually crap Experimenting with the TSC didn't result in anything satisfactory using the Fender setup.
So that's what I hope to somewhat remedy now - less boom and a useful mid control.
If needed, there are of course other ways to reduce low frequencies. But the performance of the standard F tone stack is not acceptable in this application, so that's where I'll start.

[bcook]

You're probably after the classic stack as in the 1984 schematic. You can't use the TSC to simulate it though.

[Lynxtrap]

You're probably after the classic stack as in the 1984 schematic.

What makes you think so?

[talbany]

IMO. It's a combination of many things other than just the stack!

The "Classic" Stack is going to get you closer to your typical BF Fender than the Skyliner will. So you will get more of a mid scoop due to the (Basically) same value slope resistor and mid cap and slightly higher mid pot. So if you like the Fender sound this would be IMO the way to go.If you like even less mids and a deeper scoop add the deep switch.
The Skyliner gives you more of a mid boost (around 500hZ) due to the higher value mid pot 250K and higher value slope resistor (150K), lower value .01 mid cap in the Skyliner. This won't have as deep a roll off as the .047 does since those frequency's are being sent directly to ground.If you want even more low mids raise the value of the treble cap, (mid boost") So if Boomy means more low mids then the skyline stack is your animal.

BTW. Higher value plate resistors can also shape frequency response due to the larger voltage drop across it added gain in combination with the Miller effect, thereby lowering the -3db knee cutting higher frequencies giving you the illusion of more low mids.Let's also not forget the low-end shelving effect of bypass caps.(which would be where I would start with a boomy amp) So if someone mentions there High plate Skyliner is "Boomy" you have to consider everything!

If I were to design a tone stack for a Bass guitar I would start with a Baxandall and tweak from there.

Tony

[Lynxtrap]

Thanks Tony.
Smaller cathode bypass was my first thought, and I might do that also.
But I'm still not happy with the tone stack. I want a little more control, like the bass pot cutting more bass and the mid pot controlling the..ehh..mids

This is a two channel pre amp, channel 1 is more like an Ampeg with a James, so I wanted to do something different with channel 2.
I'm thinking the jazz/rock switch will broaden the possibilities as well.

I might create a separate thread about this project.

[talbany]

Thanks Tony.
Smaller cathode bypass was my first thought, and I might do that also.
But I'm still not happy with the tone stack. I want a little more control, like the bass pot cutting more bass and the mid pot controlling the..ehh..mids

This is a two channel pre amp, channel 1 is more like an Ampeg with a James, so I wanted to do something different with channel 2.
I'm thinking the jazz/rock switch will broaden the possibilities as well.

I might create a separate thread about this project.

Well That's easy just lower the value both bass and mid pots

BTW.You have to be careful with the terminology!. For me, a term like Boomy means you are referring to a certain frequency. If you are referring to the range of the stack that's something completely different (cutting or boosting) So which is it your looking to change? Frequency or range or ..ehh..both

Tony

[Lynxtrap]

Well, I can report the results as far as my own bass playing, I use a pro to test it for real ...
Much better control over the freq bands, and the RJ switch works its magic at least as well for bass as for guitar. The pots are now usable over the their whole range.
Couple of mistakes, I accidentally left the 100K slope resistor in there. I also connected the 1nF right over the bass pot so it doesn't go to the switch.
I might look over it some more together with a bass player. There are couple of other issues that also need looking into.
Sounds great on guitar too!

Some more tweking and it should be ready to go!

[Lynxtrap]

I made a new thread about this amp over in the Technical section, in case anyone is interested in what the rest of it is.
https://ampgarage.com/forum/viewtopic.php?f=6&t=31695

[Lynxtrap]

A little update, I put it here because it concerns the tone stack.

Well, the Skyliner is definitely not "boomy" in a bass amp. In fact, I could use more lows.
While testing we ran the bass pot maxed and that gave about the right amount of lows.
Just for testing I put a 220K resistor between the pot and ground, and that seemed to do the trick, but of course the pot doesn't cut the lows enough when turned down with that resistor there.
So I guess the easiest solution would be a 1M pot? It is now 250K.
I also removed the .001 cap across the bass pot, with good result.

And the mid control didn't really sit where it should for bass. With a pro bass player, a pro bass and a pro power amp getting proper sound out of this thing, it was obvious that the mid pot needs to work in a lower register.
I changed the .01 mid cap to .047, and that did it.
Also, the mid pot might need to be linear. It didn't do much past 12 o'clock.

Also, this bass player didn't think that the "rock" mode did him any good, but I guess it could be a matter of taste and style. I think it might be useful for...well, rock.... But the "jazz" mode was definitely more neutral and nicer sounding overall for softer styles and also slapping and such.

There was treble to kingdom come, and I removed a 150K/250pf combo I had for bypass over the volume pot.

All in all, listening to the amp during test, I did not really recognize any of the "dumbleness" I'm used to from playing guitar through my ODS clone. I'm used to pretty much setting the TMB all at 12 o'clock and forget it. With a bass, all bets seemed to be off. Interesting experience.

[Reeltarded]

I dont find mid boost nor pab useful to my needs. I am thinking about PAB being a resistance to the tone stack globally and mid boost being a para value around 80-90k range total for slope...