Advice on 2nd Gen conversion to skyliner tone stack

[andresound]

O wise ones of the garage. Is such a conversion advisable/doable?

[martin manning]

Doable for sure, and as I understand it, several 2nd gen amps were "updated" in that way. You are looking at changing a couple of pots and resistors, and converting Deep to Mid Boost. Advisable is up to you. Skyliner has less mid scoop, shifted up in frequency.

[andresound]

Doable for sure, and as I understand it, several 2nd gen amps were "updated" in that way. You are looking at changing a couple of pots and resistors, and converting Deep to Mid Boost. Advisable is up to you. Skyliner has less mid scoop, shifted up in frequency.

Thank you Martin. After my 102 with skyliner stack, which I love, I was contemplating updating my 2nd Gen. Will get to it then .

[marcos]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

[talbany]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

Hello Marcos
I was wondering if and when you made this change did you keep the 1M bass and did you also change the treble pot to 250K. I generally find this 1M value to be a be boomy to my ears when set above noon. I still have my .02 cap hanging on mine.(so you recommend removing this cap?) I find this stack to have a limited range vs the standard Skyliner values. Did you find this to be the case with yours?
BTW. Do you have an opinion as to why Dumble didn't implement or modify a PAB circuit into any of his 2nd or 3rd generation amps and could this have something to do with the frequency response of the OD circuit.
Thanks!

Tony

[martin manning]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

I agree with this completely. That 20n cap is responsible for the deeper, lower frequency mid scoop in the 2nd Gen stack, which makes the controls less effective in the mid range. Even with the 500k treble and 1M bass pots retained, deleting that 20n opens it up nicely.

[andresound]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

Thanks Marcos. Only got to see the further replies too late. Have already stripped the tone stack from 2nd Gen build and nearly finished the skyliner update. Also adding another relay to accommodate PAB and OD. Changing to 12v like my 102 (works great), and removing the 5v relay board and regulator, which never worked consistently in this 2nd Gen

[marcos]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

Hello Marcos
I was wondering if and when you made this change did you keep the 1M bass and did you also change the treble pot to 250K. I generally find this 1M value to be a be boomy to my ears when set above noon. I still have my .02 cap hanging on mine.(so you recommend removing this cap?) I find this stack to have a limited range vs the standard Skyliner values. Did you find this to be the case with yours?
BTW. Do you have an opinion as to why Dumble didn't implement or modify a PAB circuit into any of his 2nd or 3rd generation amps and could this have something to do with the frequency response of the OD circuit.
Thanks!

Tony

Hi Tony,
I have also found that the original 1 M / 30% taper bass pot made it difficult to control the low frequencies. My first measure was to replace it with a 10% taper pot, which worked out nicely. Eventually, I went with a 250k pot measuring 300k. We´re talking "Rock" mode here, in "Jazz" mode the 1M pot works just fine. About the cap: As Martin pointed out, it renders the whole tone stack, especially the Mid pot, fairly ineffective, but of course, removing it will change the character of the amp, moving in the direction of a 3rd generation amp, so it depends on what you´re going for. But yes, I , personally, would remove it. You could always use a bigger cap, .02 or .033, for the Mid control, if you desire more midrange dip. As for the PAB: I guess HAD stumbled on this by accident, on the early Dumbles you could slide the Rock/Jazz switch so it would stick between the Rock and Jazz settings, yielding a preamp boost. Jelle Welagen once remarked that he dislikes the PAB with the early circuits (1st through 3rd generations), I am no big fan of that tone, either. Hope this is helpful, Marcos

[talbany]

I have also found that the original 1 M / 30% taper bass pot made it difficult to control the low frequencies. My first measure was to replace it with a 10% taper pot, which worked out nicely.

So this is why I see both Alpha 10%-15% tapers and also CTS 30% bass pots on other amps!. I also agree with the 300K pot value

As Martin pointed out, it renders the whole tone stack, especially the Mid pot, fairly ineffective, but of course, removing it will change the character of the amp, moving in the direction of a 3rd generation amp, so it depends on what you´re going for.

Having done the tone stack modeling and a bit of tweaking over the years,I have a basic knowledge of how the stack functions I get all that!
I am more interested in this!

But yes, I , personally, would remove it.

You could always use a bigger cap, .02 or .033, for the Mid control,

I actually do like the sound of a .022 mid cap in my "Classics" in my early days of tweaking those stacks. I may go back.

Jelle Welagen once remarked that he dislikes the PAB with the early circuits (1st through 3rd generations), I am no big fan of that tone, either. Hope this is helpful,

I agree with Jelle!

So it's been a while since I played my 2nd Gen I pulled it out again just to refresh my memory and have to say that with all the faults in that stack in the way of control it does have it's own character to it and works really well with both clean and OD sides so I don't really find myself needing to do much knob twisting . IMO Dumble definitely was chasing after a particular sound with these early amps that lead him to this design that has its flaws but has it's own character. The builder in me wants to change things and the guitar player in me says leave it be and just play it.. I will try some of those tweaks you recommend will check back soon

Thanks again Marcos!

Tony

[martin manning]

Since Dumble converted older amps to the Skyliner stack, it seems to me that he considered the evolution of the tone stack a continuous improvement process.

[norburybrook]

The builder in me wants to change things and the guitar player in me says leave it be and just play it..

Tony

Quote of the century


I know that feeling


M

[martin manning]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

Thanks Marcos. Only got to see the further replies too late. Have already stripped the tone stack from 2nd Gen build and nearly finished the skyliner update. Also adding another relay to accommodate PAB and OD. Changing to 12v like my 102 (works great), and removing the 5v relay board and regulator, which never worked consistently in this 2nd Gen

The treble pot and treble cap values are very significant players in the Skyliner's upper-mid character, so don't feel like you have done something unnecessary in changing those.

[marcos]

Here´s what I would do ( and have done on my 2nd gen amp): Lose the .02 cap on the bass pot (wiper to 10k resistor) , if it is in your amp . This way, the tone stack will be fairly close to the Skyliner, tonally. Also, the mid pot will be much more effective. I also used the Skyliner stack in my amp for many years, but then changed things back to what is essentially a 3rd gen stack. I like this configuration a little better, more "juicy" mids ( hope this description is helpful). Just my .02 Euro cents
Marcos

Thanks Marcos. Only got to see the further replies too late. Have already stripped the tone stack from 2nd Gen build and nearly finished the skyliner update. Also adding another relay to accommodate PAB and OD. Changing to 12v like my 102 (works great), and removing the 5v relay board and regulator, which never worked consistently in this 2nd Gen

The treble pot and treble cap values are very significant players in the Skyliner's upper-mid character, so don't feel like you have done something unnecessary in changing those.

I totally agree, no harm done. As I have mentioned, the 3rd generation tone stack and the Skyliner are not dissimilar , tonally. I have found the Skyliner eq to have a more pronounced upper-mid emphasis, which you may, or may not like. But overall, a versatile tone stack. My .02 Euro cents Marcos

[marcos]

So it's been a while since I played my 2nd Gen I pulled it out again just to refresh my memory and have to say that with all the faults in that stack in the way of control it does have it's own character to it and works really well with both clean and OD sides so I don't really find myself needing to do much knob twisting . IMO Dumble definitely was chasing after a particular sound with these early amps that lead him to this design that has its flaws but has it's own character. The builder in me wants to change things and the guitar player in me says leave it be and just play it.. I will try some of those tweaks you recommend will check back soon


Tony

Tony, I absolutely understand this feeling. With all the mods I have tried in my amp over the last 40 years, I have always tried to retain its character, as far as possible. That said, in its present state, with a few mods remaining, I like it better than ever. I understand you own more than one amp ), so no need to change anything, really. Still, looking forward to your findings
Marcos