D-tone stack vs. Fender Tone stack

[Darkbluemurder]

From comparing the schematics the differences are obvious but what is the sonic difference? So far I stuck with the 2 knob stack in my D-clones for no better reason that I did not have a third pot and/or did not want to deface the donor amp. My guess would be that the D-stack offers far more mids than the F-stack.

I just converted my 80s Concert's lead channel to a DOS channel. This is the first time I have three tone knobs! Right now it still has the original tone stack with the 10k mid pot and the push-pull mid shift (add a 1200 pf to the 330 pf treble cap but the combined caps make the sound too mushy IMHO). I would like to have a smoother tone so my idea is to

1) from the CCW side of the bass pot change the 10k mid pot to a 1k8 resistor to ground
2) from the mid cap (0.047uF) insert a 250kA push-pull pot and use the push-pull pot for the preamp boost.

What is your experience and am I on the right track with my ideas?

Thank you very much for your input.

[glasman]

You are correct, having the Mid control decoupled from the bass and treble controls provide a thicker mid range sound. I think it also makes it a little easier to find the sweet spot in the tone stack.


As far as the topography, I think I would go with 250K treble, 250 K mid 500K bass with 10K to ground from the Bass control.

Gary

[Darkbluemurder]

You are correct, having the Mid control decoupled from the bass and treble controls provide a thicker mid range sound. I think it also makes it a little easier to find the sweet spot in the tone stack.


As far as the topography, I think I would go with 250K treble, 250 K mid 500K bass with 10K to ground from the Bass control.

Gary

Gary,

Thanks a lot! I have to check the bass pot value that is in there - I believe it is a 250kA. I will try the changes first with the original bass pot and take it from there. If my memory serves me right I still have a 500kA PP so I could have the treble shift (with a smaller value to avoid muddiness) and the preamp boost

I use the amp's clean channel for the country sounds, use my Stephenson Stage Hog for the crunch rhythm sounds going into the clean channel and set the DOS channel for a fat lead sound that is louder than the rhythm sound. When I play crunch rhythm I just turn back the gain on the DOS channel. That way I can always have a considerable solo boost whereas using the Stage Hog for solos will not give me a volume boost going into an overdriven amp channel.

But I really want to be able to fatten up the lead tone for the Tele - with the humbucker guitars everything is fine as is.

[Darkbluemurder]

This weekend when I opened up my Deluxe Reverb II and checked the voltages I also wired in the D tone stack. I currently use a 100k slope, a 330pf treble cap, a .1uF bass cap and a .047uF mid cap. Pots are Treble 250kA (actually 270k), Bass 1MA, Mid 250kA w/ push-pull for midboost (adds a 820pf to the treble cap). No cap around the bass pot.

My 2c of observations:

1) the mid control works a different frequency now which is not as low as in the F stack
2) there are many more good combinations of treble and mid settings. With the F stack I used to set the treble pot to 8-9 (at lower settings I lost too much gain), mid and bass at 3 (amp becomes farty at higher settings at the gain I use). With the D stack I can use less treble and more mid to get a warmer tone at roughly the same gain level
3) bass control is in a different position, i.e. with the F-stack it is most effective between 2-4 and with the D stack it is most effective between 4-10.
4) the controls are still highly interactive (higher mid settings make treble less effective, higher bass settings seem to increase the impact of the mid control).

Overall I like it and think that it is more useable than the F stack.
Now my questions:

1) Hybrid Rev A and A1 specify a 150k slope resistor. I expect that this would make the amp brighter and tighter in the bass compared to 100k, right?
2) I tried a 1000pf cap around the bass pot in the F stack. It did not make any difference I could hear. A 10nF (=0.01uF) gave much less bass. The 1000pf cap is probably a very subtle difference but what is its effect in the D stack?

As always I appreciate your input and experience and I will very soon implement the D stack in my Concert, too.

[jaysg]

I have the same amp as you -- '83 Concert. You will be happier when you have modified the tone stack. As you found with the smaller amp, the D stack is more continuously useful. imo, there are only two or three useable tones on a BF stack -- good tones, but little control over midrange.

[dogears]

You should absolutely wire in the exact D stack recommended in these parts..... 150k slope, .001 on the 500ka bass pot (not 1Ma), .01uf midcap (try it or make it switchable)

Get the baseline using the exact circuit the man used. Gotta get a baseline IMO.

This weekend when I opened up my Deluxe Reverb II and checked the voltages I also wired in the D tone stack. I currently use a 100k slope, a 330pf treble cap, a .1uF bass cap and a .047uF mid cap. Pots are Treble 250kA (actually 270k), Bass 1MA, Mid 250kA w/ push-pull for midboost (adds a 820pf to the treble cap). No cap around the bass pot.

[llemtt]

..The 1000pf cap is probably a very subtle difference but what is its effect in the D stack?
..

It helps the treble to be less interactive from mid-bass controls, actually it also lowers a little the response around 15-20khz.

I have plenty of TS graph on another pc at home, I'll go and search for this one to post later.

teo

[Darkbluemurder]

You should absolutely wire in the exact D stack recommended in these parts..... 150k slope, .001 on the 500ka bass pot (not 1Ma), .01uf midcap (try it or make it switchable)

Thanks Scott! I should have all the parts you mentioned except I am not sure whether I still have 150k resistors as metal film. If I don't I'll use 120k or 130k until I have 150k metal films. I was reluctant to try the .01 mid cap since in a F tone stack the tone got quite muddy in overdrive mode. In addition, both A1 and Rev A specify a .047 mid cap. Are you saying that the schems are incorrect in that respect?

Anyway since I noticed that the D stack shifts the mid control up .01 should work well. I'll make it switchable if I still have a P/P 500kA pot.

[Darkbluemurder]

..The 1000pf cap is probably a very subtle difference but what is its effect in the D stack?
..

It helps the treble to be less interactive from mid-bass controls, actually it also lowers a little the response around 15-20khz.

I have plenty of TS graph on another pc at home, I'll go and search for this one to post later.

teo

Teo,

Thank you very much! So it is clear it should be in as these changes absolutely make sense. The graphs would certainly help as my version of the Duncan TS calculator does not include a D style stack and - as I learned - the D and F stacks behave differently.

Cheers DBM

[Darkbluemurder]

I have the same amp as you -- '83 Concert. You will be happier when you have modified the tone stack. As you found with the smaller amp, the D stack is more continuously useful. imo, there are only two or three useable tones on a BF stack -- good tones, but little control over midrange.

Jay,

You were absolutely right. Tonight I changed the Concert's tone stack as well. Since this amp is basically a 70s style I put in the following values:

Treble: 330 pf, 250kA
Bass: 0.1uF, 250kA, 10k to ground (I tried 1k8 too but 10k makes the amp sound fuller)
Mid: 0.047uF, 250kA with Push-pull for preamp boost.

Gotta try Dogears' tweaks tomorrow on the small amp to make it closer to Hybrid Rev A. I will report the results.

[Darkbluemurder]

You should absolutely wire in the exact D stack recommended in these parts..... 150k slope, .001 on the 500ka bass pot (not 1Ma), .01uf midcap (try it or make it switchable)

Thanks Scott! I should have all the parts you mentioned except I am not sure whether I still have 150k resistors as metal film. If I don't I'll use 120k or 130k until I have 150k metal films. I was reluctant to try the .01 mid cap since in a F tone stack the tone got quite muddy in overdrive mode. In addition, both A1 and Rev A specify a .047 mid cap. Are you saying that the schems are incorrect in that respect?

Anyway since I noticed that the D stack shifts the mid control up .01 should work well. I'll make it switchable if I still have a P/P 500kA pot.

OK, a few more changes. The stack is now as follows:

Treble 330p, 250kA, slope 120k (did not have a 150k but the difference to 100k was noticeable)
Bass 0.1u, 500kA with 0.001u cap, 10k to ground
Mid 0.047, 250kA
Treble shift unchanged.

I have ordered metal film resistors so I definitely will replace the 120k for a 150k since even the 120k made the bass response noticeably tighter.

Thanks for all your input.