Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubenit on March 21, 2019, 05:59:16 am
-
The Dumble style amps usually are "mostly" dependent on the tone from the clean channel (tone stack) going into the OD
channel. I've tried a treble cut in the OD and a pseudo 5E3 tone stack with some limited success but neither seemed very versatile.
I've pondered trying a James tone stack for a few years but haven't gotten around to it. Then I built the Carolina Overdrive Special 5879 which has ALOT of gain available in that it has 3 gain stages in the clean then going into two gain stages in the OD with latter being the 5879 pentode.
In fact, it had so much gain available that I found I kept turning the drive pot (between the two OD gain stages) down quite a bit. Turning the drive pot up started giving it a distorted (vs. overdriven) tone that I didn't care for. However, I liked the tone I was getting turning up the trim pot or the level pot in the OD channel. But the drive channel was usually "set and forget" to get my preferred overdriven tone.
Knowing the James tone stack has some "loss" to it, I kept thinking it might be a reasonable option going into a drive pot?
And I know from years past that the JTS has quite of bit of tone shaping in it given it's only a two knob tone stack. I had enough time in my schedule to give the experiment a go.
And I had found from using an EQ pedal in the FX loop that shaping the tone coming from the OD gave a bunch of tonal options for the overdrive sound particularly doing a "mid hump" shaping.
Regarding the frequency graphs below..... while all the settings sound good to me, I am probably getting my best preferred OD cranked tone with the JTS 4 dialing where the treble is set to 7 & the bass set to about 4.5.
-
I am quite pleased with the results!! :thumbsup: :thumbsup:
I've built the Tweed Overdrive Special, the Tweed BluezMeister, the D'Mars ODS and this Carolina Overdrive Special (& modified variations of each). I've never found a tone stack that was very versatile. Most I could come up with simply removed some of the highs that contributed (at some level) to some harshness IF the OD was pushed/cranked a lot.
This tone stack is VERY versatile and some of the benefits from it are:
- The OD tone can be dialed in such that the OD channel doesn't favor humbuckers over single coils. Both sound good.
- I can get the OD mid-scooped and it sound more like a boost to the clean channel then an overdriven tone.
- Sometimes an amp tone sounds great at home but gets loss in the mix with a band. I think you could shape the OD tone
to cut thru the mix reasonably well using the James tone stack.
The biggest benefit I have experienced from it is that it allows a much wider bandwidth of dialing the trim pot, the drive pot and the level pot. Rather then previously dialing up the trim and level pot but leaving the drive pot "set", I can shape the tone and the flavor of the OD channel MUCH better. I am thinking of this in two regards: 1) the tone of the OD & 2) the degree of transparency to overdrive to a musical distortion (vs. a non musical distortion).
So, now cranking the OD louder gives a ton of musical sustain that I like. In fact, the amp will now feedback some when I want it to. It is important to note that the JTS seemed to shape the previous "cranked" OD tone (which began sounding distorted) to a very musical cranked OD tone. Kind of hard to explain but it's something that was easily audibly different, IMO.
So this JTS will stay in the amp & I am having great fun with it! IF I get a chance, I will record some sound clips within the next few weeks to demo the versatility of the JTS.
I don't know if something like this would work with the Tweed BluezMeister that doesn't have as much gain to it as my COS? It might be a good option for an OD tone stack with the Tweed Overdrive Special.
Just thought I'd pass this idea on for anyone who might like to experiment with it.
With respect, Tubenit
-
Thanks for posting this! When I do use a tone stack, it's always the James. I like it far better than the standard FMV. And it's supposed to actually be less lossy. I like the way you can make it either mid scooped or mid boosted too. You can even put a "shift" pot in the middle, in place of the fixed resistor for a bit more subtle shaping.
-
Tubenit, How did you decide on the component values used on the JTS? THX, j
-
How did you decide on the component values used on the JTS?
Two ways ………………
1) I used the Duncan Tone Stack Calculator
2) I've used the James Tone Stack on numerous amps including the Carolina Blues Special (which was sort of like a
5E3 Deluxe but with reverb and the JTS). And I always liked how it sounded with those values.
With respect, Tubenit
-
Thanks, looking for something different, thinking bout trying a JTS. :icon_biggrin:
-
I've now had quite a bit of play time with this James OD tone stack. I am super happy with it! :happy1: :thumbsup:
Using this:
- gives me the best contrast between clear clean tone and a overdriven tone. Clean is truly clean and OD is truly overdriven
- you can easily adjust the James tone stack to find a great tone for single coils OR humbuckers in the OD channel. The
D-inspired amps I've tried (Tweed Overdrive Special, Tweed BluezMeister, D'Mars ODS & the COS) have been more
favorable to humbuckers in the OD channel and less so to single coils. While single coils and humbuckers always sounded
good to me in the clean channel
- notes bloom & sustain more with this JTS then anything else I've tried as a OD tone stack. It's relatively easy to sustain
into feedback
- the JTS dialing does offer both a mid-scooped OD tone (more crunch/rock) and a pseudo/faux midboosted OD tone which
is smoother to my ears
- you can dial in the JTS so chording doesn't start to mush/mud together and notes still are articulate
- it hasn't added any floor noise at idle
As an FYI, I do ALOT of experimenting with my amps and try many many mods in them. Only a portion of the mods I try do I ever post anything about. I would guess IF I try 10 mods, I might keep 3 (or less) of them and reverse the other 7.
IF you have a D-style inspired amp & you can't get both a good clean AND OD tone, this might be worth a try for you? I wished I had tried this about 3 years ago. It's helped dial in "that" tone I've had in my head for a long time.
I will try to get a decent sound clip done with this soon.
With respect, Tubenit
-
Interesting stuff mate. I'm halfway through creating a DIYLayout for these changes.