Updated Bassman Dclone Layout

[Normster]

This is the most correct version to date. Please let me know if there are any errors and I'll correct them.

The previous version had the Master/OD input connections reversed on the channel switch. (Thanks, Ampdoc!)

Edit: More corrections per Dogears.

[img846]http://bad-domain/Pics/Bassman_Dclone_LayoutV3.jpg[/img]

[dogears]

Norm,

You have the 150k resistor from OD2 feeding a 1M master directly. You can't do that. Are you sure this is how the amp is??

Actually, you also have the 150k and 100k resistor positions swapped on OD1 and OD2.......

To anyone following this diagram, you need to add a 100k trimmer before the 1M OD master. Or, use a 200k resistor instead of the 150k, then hang a 50k across the outerlugs of the master pot. This simulates an OD level pot up halfway and correctly loads against the .0047 cap.

The amp would sound like muddy crap with 1M against the .0047....IMHO

I'd also suggest putting the 1uf bypass cap on CL2 and not OD2. Unless you do an HRM. I have switchable bypass caps on mine and in non HRM, 4.7uf on OD2 sounds better......

I prefer .02uf on the PI as well. This is the baseline, imo, and should be tweaked down only after trying the .02uf

One other thing is to use a 500pf to bypass the 220k CL2 grid. THat was the Dumble value. Once again, start with the baseline and reduce in the tweak process. Don't start with non baseline values.

I think a 150k/2.2 plate/cathode setup would be good on a non HRM OD2.....

[Normster]

OK, I changed the diagram as follows:

Swapped 150k and 100k resistor positions on OD1 and OD2.

Changed 1MA OD Level pot to 100kA per Hybrid-A. (That's actually how it is on my amp. The 1MA was leftover from an early HRM drawing and I didn't spot it during the redraw.)

Put the 1uf bypass cap on CL2 and 5uF on OD2.

Put .02uf on the PI. (I went with .01uF to compensate for really muddy iron.)

Put a 500pf to bypass the 220k CL2 grid.

Put 150k/2.2 plate/cathode on OD2.

Anything else? (Thanks, Scott!!!)

[Robert]

Hey Norm,

I always loved your earlier layouts and used them to design my boards with. Thanks much!! Its also nice to see some of Dogears knowledge put on paper. I notice you didn't include the 4M7 resistor to ground after the 300pF treble cap. Any thoughts on that one?

[Normster]

Hey Norm,

I always loved your earlier layouts and used them to design my boards with. Thanks much!! Its also nice to see some of Dogears knowledge put on paper. I notice you didn't include the 4M7 resistor to ground after the 300pF treble cap. Any thoughts on that one?

IIRC, the 4M7 is only needed when using the mid boost circuit (.0022pF/390pF treble caps?) to prevent popping when switching. On this one, I just used a 330pF treble cap and ommitted the mid boost.

[mat]

Hi Normster and thanks for the new layout.

I'm having trouble too read the orange drop values. The picture is 210kB. I can't seem to get the bigger picture when clicking the thumbnail picture.

Mat

[Normster]

Hi Normster and thanks for the new layout.

I'm having trouble too read the orange drop values. The picture is 210kB. I can't seem to get the bigger picture when clicking the thumbnail picture.

Mat

I'm not sure why it won't come up for you. Try saving the picture directly from this link: http://bad-domain/Pics/Bassman_Dclone_LayoutV3.jpg

[mat]

Hi Normster and thanks for the new layout.

I'm having trouble too read the orange drop values. The picture is 210kB. I can't seem to get the bigger picture when clicking the thumbnail picture.

Mat

I'm not sure why it won't come up for you. Try saving the picture directly from this link: http://bad-domain/Pics/Bassman_Dclone_LayoutV3.jpg

I'm getting the 210kb picture also when saving directly. The earlier versions were clearer on the capasitor values. The bigger size picture opens now when clicking the picture but it is also blurry on the o-drops values ?

Am I correct saying that the orangedrop values are from left to right:
0.1u/600V - 0.1u/600V - 0.1u - 0.03u - .01u - 0.047u - .01u - .047u - .01u - .047u and on V1 .047u and on bass pot .001u and on volume pot .0047u ?

[Normster]

Pretty close...

Left to right: 0.1uF, 0.1uF, 0.1uf, 0.02uF, 0.01uF, 0.0047uF, 0.01uF, 0.047uF, 0.1uF, 0.047uF

0.001uF on bass pot, 0.0047uF from R/J to volume pot, 0.047 on the local feedback loop

[mat]

Pretty close...

Left to right: 0.1uF, 0.1uF, 0.1uf, 0.02uF, 0.01uF, 0.0047uF, 0.01uF, 0.047uF, 0.1uF, 0.047uF

0.001uF on bass pot, 0.0047uF from R/J to volume pot, 0.047 on the local feedback loop

Thanks for the quick answer

[dogears]

I'd suggest two things....

First, use the 250ka midpot of the Skyliner. More flexible and same tones. Just capable of more mids which you may need for suggestion 2.....

Next, consider the .01uf midcap. All the way on the right...... I prefer it as do many... Dumble himself retrofitted this tonestack into many 80s amps. You could always add a switch that adds a .033uf in parallel with a .01uf so you cna have both sounds.... The .01uf midcap responds well with the 250ka midpot. Hence my above suggestion.

Ooh.. two more things.....

The OD level pot should be a 100kb linear IMO. Definately....

Also, try a 180k resistor instead of the 220k that feeds the 100k od trimmer. A bit more dynamic tone.... Me likey.

[mat]

I'd suggest two things....

First, use the 250ka midpot of the Skyliner. More flexible and same tones. Just capable of more mids which you may need for suggestion 2.....

Next, consider the .01uf midcap. All the way on the right...... I prefer it as do many... Dumble himself retrofitted this tonestack into many 80s amps. You could always add a switch that adds a .033uf in parallel with a .01uf so you cna have both sounds.... The .01uf midcap responds well with the 250ka midpot. Hence my above suggestion.

Ooh.. two more things.....

The OD level pot should be a 100kb linear IMO. Definately....

Also, try a 180k resistor instead of the 220k that feeds the 100k od trimmer. A bit more dynamic tone.... Me likey.

Well I'm definitely going to follow Your suggestions - Love Your sound ! (and playing).
Thanks for the tips !

[keithrick]

I'd also suggest putting the 1uf bypass cap on CL2 and not OD2. Unless you do an HRM. I have switchable bypass caps on mine and in non HRM, 4.7uf on OD2 sounds better......

One other thing is to use a 500pf to bypass the 220k CL2 grid. THat was the Dumble value. Once again, start with the baseline and reduce in the tweak process. Don't start with non baseline values.

[George Adzich]

Dogears,

In your last reply, did you mean to say that the "OD Drive pot should be linear"

You stated that it is the "Level pot that should be linear". I noticed on Norm's layout that he has the Drive pot as a linear pot. I meant to ask about the earlier, but now that you mentioned it, I thought I would get a clarification.


As always, THANKS for the help for myself and the forum in general.


-George

[Darkbluemurder]

My feeling is that a 100kB level pot would make the amp very loud at very low settings and difficult to control - I don't know for sure because I only used either 100kA or 250kA (the latter with a 220k resistor to ground from the pot's wiper).