It is a low plate version, with switchable Skyliner (that usually stays on the classic setting)
Is this some sort of switchable stack you implemented or is classic setting a certain way you set the skyline.. If it's been modified perhaps you could post a schemo or layout on the switching system..
Tony
I got so tired of trying to document every change I'd been making that I stopped trying. So I'll have to go back and try to retrace the schematic.
Here's what I remember: all I changed was the mids on my skyliner switch. I recall that the main difference was the mid pot value and the mid cap. So I used a pot with a dpdt switch to switch in an additional capacitor and also a resistor across the mid pot to change its overall value.
I'm kind of surprised you want more bass than you are getting.
I have 5uF bypass caps across the board and I think I have enough low end.
Mine is switchable Skyline with a .01uF and .05uF that I can parallel. (250K mid pot)
Sometimes I feel like I could use more bass in overdrive but that is the balancing act with the non HRM.
With my EVM 12L speakers in my Vox 2 x 12 it woofs pretty good at volume.
At lower volumes bass is always a commodity as you just aren't moving enough air to get much.
I've kind of moved away from my single coil guitars with this amp.
I rediscovered a dual humbucker guitar I have had for years but never played much. This amp much prefers humbuckers.
Maybe it's the input, I don't know. I did end up with a 33K grid stopper on V1a.
In a band situation which I have not played this amp in, I wouldn't want any more bass, and possibly would have to shave some off because I have found if you compete with the bass guitar at all that it can make for a muddy overall mix.
After a lot of tweaks I pretty much came full circle and ended up with the 101 non HRM schematic.
whats your slope resistor value? Somethings not right here if youre running 22/22 and dont have good bass still. Maybe its the power section/PI? What value cap is at pin 2 on the PI? if it's too low youre going to have less bass overall on both channels
It's true i've lost my marbles and i cant remember where i put them
Plate driven tone stacks are not the most efficient way to drive an RC filter network.. especially in a high plate 220k configuration.. The tone stack is a filter network that is designed to ideally be driven from a zero source impedance to achieve it's proper frequency response. (this is why cathode follower driven stacks like in Bassman/Marshall's) are inherently brighter and provides greater range due to it's very low source impedance that allows the tone stack to work as designed. If the tone stack is driven from too large a source impedance (220K), not only will there be a loss of gain, but there will be a different frequency response to the network, typically quite a few dB loss of the highs which is a part of the reason why high plates are slightly darker.. This IMHO effects it's theoretical frequency response.
The way I look at it in the case of the higher impedance plate driven stack in conjunction with the higher value 250K mid pot lifting the load this makes for a less than efficient design IMO,, In the case of the Dumble/Fender TS both mid and bass caps are in parallel so when you alter the frequency response or loading of one it effects the other..
Any others have an opinion?
Tony
" The psychics on my bench is the same as Dumble'"
I need to go ahead and document my build better. Is there any free/cheap software that I could use to modify some existing file that would help me document the changes?
I'd like to start working from Mark's "Tweeked D'Lite Schematic."
Don't know that schematic. But I use (and it seems many others do as well) ExpressSCH. It's free and very easy to learn. You can download tube amp component library from the Hoffman Amp forum.
I need to go ahead and document my build better. Is there any free/cheap software that I could use to modify some existing file that would help me document the changes?
I'd like to start working from Mark's "Tweeked D'Lite Schematic."
If so, it looks like he used ExpressSchematic to create the original, then converted it to PDF.
You will need to ask the original author (mdroberts?) to email you the original .sch (expressSchem) version, then you will need to download the free expresschem program in order to open the file & be able to edit it.
Thanks for that. I'll see what I can do to get my build documented properly so that y'all don't have to chase so many ghosts trying to help me with this!
If I have any huge insights in the meantime, I'll let you know.
I need to finish documenting the full build, but as a start I thought I'd look at the tone stack. I may have tracked down the issue with too little bass, so let me run this past you guys. I rounded up the following tone stack values:
D'Lite with standard high plates
Treb - 250k Linear
Mid - 250k Linear, .01uF
Bass - 500k Audio
On mine, I was trying to implement a switch via a push-pull pot on the mid knob that would do two things:
1. In the classic position, it shorted across a .02uF cap leading to the mid pot. That's in series with a .05uF, so it has .05uF for the total mid cap. In the Skyliner position, it opens up the other cap, so the total combined capacitance is .014uF, close to the Skyliner value.
2. In the Skyliner position, the switch shorts across the wiper and one lug of the 250k mid pot, just like normal. In the classic position, it switches a resistor in in parallel across that gap, so that it lowers the resistance. At 12:00 in the Skyliner position, it measures about 59k on my pot. In the Classic position, it measures about 36k.
So...I'm wondering if it is just as simple as putting in a 500k bass pot instead of the 250kA that is in there currently. But with the way the pot is wired, halfway up on the bass control would be only 25k of difference, wouldn't it? (halfway up 500k on an audio taper is 50k, and it's 25k for the 250kA pot)
Last edited by greiswig on Tue Nov 02, 2010 5:41 pm, edited 2 times in total.
greiswig wrote:I need to finish documenting the full build, but as a start I thought I'd look at the tone stack. I may have tracked down the issue with too little bass, so let me run this past you guys. I rounded up the following tone stack values:
D'Lite with standard high plates
Treb - 250kB
Mid - 250kB
Bass - 500kA
Skyliner #124
Treb - 250k
Mid - 100k
Bass - 250k
Classic #124
Treb - 250K
Mid - 250kA
Bass - 500kA
On mine, I was trying to implement a switch via a push-pull pot on the mid knob that would do two things:
1. In the classic position, it shorted across a .02uF cap leading to the mid pot. That's in series with a .05uF, so it has .05uF for the total mid cap. In the Skyliner position, it opens up the other cap, so the total combined capacitance is .014uF, close to the Skyliner value.
2. In the Skyliner position, the switch shorts across the wiper and one lug of the 250k mid pot, just like normal. In the classic position, it switches a resistor in in parallel across that gap, so that it lowers the resistance. At 12:00 in the Skyliner position, it measures about 59k on my pot. In the Classic position, it measures about 36k.
So...I'm wondering if it is just as simple as putting in a 500k bass pot instead of the 250kA that is in there currently. But with the way the pot is wired, halfway up on the bass control would be only 25k of difference, wouldn't it? (halfway up 500k on an audio taper is 50k, and it's 25k for the 250kA pot)
Hi greiswig,
I would recommend to use "Lin" or "L" for "linear taper" and "Aud" for "A" for "audio taper" when posting on an international forum like this one. AFAIK the "B" or "b" has been used rather differently in different countries, in different periods of time and by different manufacturers.
G
Without a schematic and a spice sim. it's hard to tell what exactly is going on..But from what I can tell the problem shouldn't be in the switching of cap values but the load values on the pot's... In order to change those 2 stacks your going to have to change the load value of both the mid pot and the bass pot.. In the mid pot you would need to switch in a 180k resistor on the end terminals on a 250k pot gives you 104k (classic value).. For the bass pot do the same switch in a 250k resistor on a 500k pot gives 250k (classic value)....Keep in mind this changes the taper(more linear) somewhat..Another common hint is to use (2) 250k resistors from each outer leg to the wiper to preserve more of the original taper (tougher to switch)..
Other things that might be effecting it are
The 10k bass tail resistor to 1.8k
The .005 cap on outer lugs of the bass pot
The slope from 100k (classic) to 150k Skyliner
FWIW.. The Classic IMHO offers the greatest range of controls and versatility of all the ODS I've done.. If it were me I would do the classic stack and would do the switch between the .047 and .01 mid..and do a mid lift switch (start 68k) or mid lift PAB and or center off RJ switch.. This should cover a ton of ground..
Hope this helps you!!
Tony
Last edited by talbany on Tue Nov 02, 2010 6:00 pm, edited 1 time in total.
" The psychics on my bench is the same as Dumble'"
