Bass control behavior...normal?

[greiswig]

My bass control on my D'Lite seems to act funny to me, and I wanted to check it out with the rest of you.

If both the treble and mid controls are down all the way, and you start turning up the bass control, it lets through a lot of treble and mids, too. Turning the bass control up just kind of keeps turning up the volume. Then about 2:00 or so on the bass control, the treble and high mids start to get muted, and the bass starts to really come out. Then it's mud city after about 3:00-4:00.

Something doesn't seem right here, but maybe this is normal?

[Bob-I]

That doesn't seem right. The tone controls should act fairly normal except that the trable control is fairly subtle.

[greiswig]

Well, I guess what constitutes "normal" is the question. It certainly doesn't act like the Fuchs ODS30 that I've got staying as a guest, but I have no idea what the tone stack is in the Fuchs compared to the D'Lite.

[Bob-I]

Well, I guess what constitutes "normal" is the question. It certainly doesn't act like the Fuchs ODS30 that I've got staying as a guest, but I have no idea what the tone stack is in the Fuchs compared to the D'Lite.

What I mean by normal is all 3 controls add some volume but not dramatically, and each controls it's respective range. Turn up the bass and you get more bass, and a little more volume, same for mids and treble.

I'd say the tone stack wiring is not 100%. Run through it again using the layout to verify your wiring.

[greiswig]

I did go through the wiring again, right down to making sure that the right pot connections were actually making contact with the right relay connections using my continuity tester.

Could someone with a D'Lite style tone stack try this test and report back?

1. Turn the treble, bass and mid all the way down.
2. With something playing through the amp, bring up the bass knob slowly.
3. On my amp, a virtually identical mix of treble, mids and bass come through until the bass is at 12:00. At that point, more bass starts to come through, but there is still a lot of treble and mid in the mix. Enough that playing a guitar through the amp doesn't sound too bad. After that point, there seems to be a phase shift sound at about 3:00, after which the trebles and mids actually start to attenuate, and the bass really starts to jump out.

I'd really appreciate the reality check, and if this isn't normal, I'd love to hear ideas about what kind of miswiring might cause this...I may just be blind.

[heisthl]

Bass pot wafer is not connected to the solder lug (P3, ground lug - the left one when viewed from the back with the lugs on the top )? Replace the pot.

[greiswig]

Bass pot wafer is not connected to the solder lug (P3, ground lug - the left one when viewed from the back with the lugs on the top )? Replace the pot.

Thanks for that,heisthl. I had already pulled that pot and replaced it: the first pot measured a little funny: turning the control all the way one direction measured 477k between that outer lug and wiper, and measured 900k between the other outer lug and wiper when rotated in the opposite direction. I'd measured the new pot before I put it in, and it read as I would have expected. However, it did not change this behavior that I'm describing except for changing where in the sweep the change from passing highs to not passing them occurred.

If I ground the high side of the treble pot, the bass control acts as I would expect. Given the circuit, I guess that didn't surprise me. But as I look at it, with the low side of the treble pot feeding the wiper of the bass pot, I wonder if this treble bleed into the bass pot is normal?

Can someone tinker with the controls on their amp and make sure that they don't act this way too, to help me figure out whether I'm chasing my tail or not? I mean, treble and mid down all the way is not an ordinary tone setting for most people. Maybe I'm just being paranoid.

[Structo]

Is your tone stack wired like this?

[Structo]

Is your tone stack wired like this?

[greiswig]

Is your tone stack wired like this?

Hey, Tom. With the exception that I don't have the jumper on the bass pot, yes. I gather your tone stack doesn't do what mine does?

[greiswig]

Could someone with a D'Lite style tone stack try this test and report back?

1. Turn the treble, bass and mid all the way down.
2. With something playing through the amp, bring up the bass knob slowly.
3. On my amp, a virtually identical mix of treble, mids and bass come through until the bass is at 12:00. At that point, more bass starts to come through, but there is still a lot of treble and mid in the mix. Enough that playing a guitar through the amp doesn't sound too bad. After that point, there seems to be a phase shift sound at about 3:00, after which the trebles and mids actually start to attenuate, and the bass really starts to jump out.

C'mon, somone... pretty please?

[greiswig]

Okay, here's another related question: what is the purpose of the .001uF cap across the bass pot lugs? Is that to shunt highs to ground?

Here's why I ask: if I put the jumper back in (per original D'Lite) between the bass pot wiper and the lug closest to the input jack, lo and behold the bass control acts as I'd expect it to. Very little highs in that control.

But the "no bass mod" diagrams I've seen all have the .001uF cap across the outer two lugs on the bass pot. No difference if the jumper is in place, but a big difference if you cut it.

With no jumper, is that cap supposed to go between the wiper and the outer lug with the 10k resistor to ground?

This might explain why some people have had a hard time taming the highs on their amp. If they've omitted that jumper, but still have that cap on the outer two lugs, some highs are creeping through the bass control no matter what your treble pot setting is.

[Deric]

Just tried it...

If I just pluck the low E string while turning the bass control up, I get a very steady and smooth rise in the bass thru the entire range of the pot. Plucking just the high strings, the high content comes up very slowly to about 12 o'clock and then stays put - it does not seem to increase OR decrease after that.

Strumming an open E or G chord, I get an effect similair to what you are describing. Bass Mids and Highs seem to come on slowly to about 12:00. At that point the Bass starts to over power the Mids and Highs. I do hear a sort of phase shift effect around 3:00 but it seems to be more that the Bass is just drowning out the Mids and Highs as opposed to cancelling them out. I do not notice this effect when just plucking the low E or just the high E and B strings.


Hope that makes sense.

[dogears]

You must have the input and wiper connected. That is the correct way. The relay breaks that connection in PAB mode.

Bass mod, shmase mod. Dumble connected the lugs and he designed the stack

[greiswig]

Okay, here's another related question: what is the purpose of the .001uF cap across the bass pot lugs? Is that to shunt highs to ground?

Here's why I ask: if I put the jumper back in (per original D'Lite) between the bass pot wiper and the lug closest to the input jack, lo and behold the bass control acts as I'd expect it to. Very little highs in that control.

But the "no bass mod" diagrams I've seen all have the .001uF cap across the outer two lugs on the bass pot. No difference if the jumper is in place, but a big difference if you cut it.

With no jumper, is that cap supposed to go between the wiper and the outer lug with the 10k resistor to ground?

This might explain why some people have had a hard time taming the highs on their amp. If they've omitted that jumper, but still have that cap on the outer two lugs, some highs are creeping through the bass control no matter what your treble pot setting is.