Verified Steel String Singer

[markusw]

I could be wrong but I I think it was Martin who ran the circuit through spice. While on the same tack he came up with rotary switch values that work well. If not, oh well. Here's the link to his better filter values:

https://ampgarage.com/forum/viewtopic.php?f=5&t=30118

Here is a link to the results of the LTSpice simulation with a 300 uH inductor.
https://ampgarage.com/forum/viewtopic.p ... or#p206073

Take care,

Markus

[talbany]

my understanding is the inductor does absolutely nothing to the tone so not having it there is the same as having it there

I could be wrong of course on this.


M

I too remember someone here on the forums saying they did a detailed analysis of the circuit with spice or some other software and could clearly state that there is 0 impact to the inductor in he circuit. I'm no expert myself, so I'm only relaying what's been said here.

I'm not an expert either, but I wonder if the inductor really is doing something (at least in the early models) and the community is just not getting the filters 100% correct? My only reason for thinking this -- and perhaps I'm speculating -- is that the guys at Two-Rock, who have been inside SSS #002 and #004 (as well as some Dumblelands) (and thus have had more inside knowledge of these amps than perhaps anyone) still use an inductor on their SSS builds. And I'm presuming that they are smart guys, so presumably if when inside they saw that it does nothing, they wouldn't have bothered including it? Or maybe I'm give them too much credit, and they simply missed it but we've caught it? Or perhaps they too noticed it, but still include just for the sake of accuracy? In any event, Dumble ditched the inductor by SSS #005; it's been confirmed by Brandon that there wasn't an inductor in #005, so perhaps Dumble discovered his mistake or simply redesigned the filter network of the earlier SSS amps to no longer require an inductor?

Band Pass Filter using R, L and C Components
Band Pass Filter circuit design by using inductor, capacitor and resistor is given as below:

3.-Band-pass-filter-circuit-using-R-L-and-C-components.jpg

The centre frequency of the band pass filter which is also termed as ‘resonant peak’ can be formulated by using the below equation:

fc = 1/2π√(LC)​

Where L = inductance of an inductor whose units are in Henry (H).

C = capacitance of a capacitor whose units are in Farad (F).

We can also design a band pass filter with inductors, but we know that due to high reactance of the capacitors the band pass filter design with RC elements is more advantage than RL circuits.

This is (basically) the same filter network Ampeg used on their SVT and other amps (via rocker switches).Perhaps Dumble had a setting he liked?? Clearly the SSS was inspired by the SVT (AB2).I can also say that jumping this filter out in my #002 clone has little effect on the sound. This would be a question I would want to ask Dumble if given the chance?
BTW.AFAIK The (Hi-Lo) filter array in the hand drawn #002 from Japan is correct! However impractical on some settings . I believe the one Martin posted a while back is better suited for 6 string electrics IMO..
Tony

[jfs322]

I could be wrong but I I think it was Martin who ran the circuit through spice. While on the same tack he came up with rotary switch values that work well. If not, oh well. Here's the link to his better filter values:

https://ampgarage.com/forum/viewtopic.php?f=5&t=30118

Here is a link to the results of the LTSpice simulation with a 300 uH inductor.
https://ampgarage.com/forum/viewtopic.p ... or#p206073

Take care,

Markus

But doesn't the LTSpice simulation assume that the way this community currently understands the filter circuit is correct? And in that sense, it's a little question-begging, because precisely what is at issue is whether we have the understood filters correctly. In other words, if the way we currently understand the filter circuit is not accurate, then the LTSpice simulation tells us nothing because it's based on an incorrect understanding of the circuit. So in a sense, there's a hint of circularity to it: It's trying to use data to prove that our understanding must be correct, yet that data is founded on the very understanding that we're trying to prove...

[rccolgan]

my understanding is the inductor does absolutely nothing to the tone so not having it there is the same as having it there

I could be wrong of course on this.


M

I jumped the inductor with a wire and I could not hear any audible difference. In fact, I didn't hear a "pop" at all when I made the connection when the circuit was live so I really don't think it's important in my opinion.

Two Rock uses two of these stacked together on their Custom Cleans Toroidal inductor for graphic EQ, 390MH (519390) For SSS #002, you could just use one or pick up this one which is pretty darn close to the original Triod: Vitec 300mH 57P1838

[martin manning]

jfs, you are right, of course. Here's some bench testing that confirms that the inductor has no effect in the filter circuit as it is presently understood: https://ampgarage.com/forum/viewtopic.p ... 95#p208695

If the Japanese schematic is correct as Tony says, it does work, IMO not very well, and it's a proven fact that the inductor isn't doing anything in that circuit. I revamped it to make the high and low controls less interactive and more uniform in their effect (see link above). I also removed the so-called bypass setting, which would be better with a separate switch if that is wanted. The revised filters work very well, and have been built, tested, and demo'ed by several forum members.

[talbany]

The inductor and filters are always asked about by the newbies and the conversation generally always goes something like this

? What does the indicator do
answer; Not much
? Why did he use it?
answer: Don't know?
? Should I not use it
answer: I guess

Hi -lo Filters.
? Do the filters in 002 schematic work
answer:Yes but not very well
? should I use it
answer. No ...Use Martins

6 months/year later.......................What does the inductor do?

Please sticky this!

[talbany]

Btw. while we're on this I'll add

My experience w/002's filters (before I modified it)
It seemed clear to me the filters in 002 were setup for more than just 6 string electrics.. It was obvious that a few lo filter settings were there for Bass guitar or for pedal steel. A friend Robbie Flint who plays steel with Alan Jackson used some of these settings and the amp sounded fine. There were also a few settings there that sounded fine for guitar and if I played Steel or Bass or Leslie I would have left the 002 filters in. So IMO the amp was more versatile with its original 002 filters.
So the question is not better or worse it's what instrument your playing and what cabinet it's running through

Martin's array is centered better for 6 string electrics and I rarely touch them.... IMO

Tony

[beasleybodyshop]

Btw. while we're on this I'll add

My experience w/002's filters (before I modified it)
It seemed clear to me the filters in 002 were setup for more than just 6 string electrics.. It was obvious that a few lo filter settings were there for Bass guitar or for pedal steel. A friend Robbie Flint who plays steel with Alan Jackson used some of these settings and the amp sounded fine. There were also a few settings there that sounded fine for guitar and if I played Steel or Bass or Leslie I would have left the 002 filters in. So IMO the amp was more versatile with its original 002 filters.
So the question is not better or worse it's what instrument your playing and what cabinet it's running through

Martin's array is centered better for 6 string electrics and I rarely touch them.... IMO

Tony

It seems clear that the Low filter was HADs attempt at a Audio taper control. Martin's S taper configuration does the exact same thing except it's more consistent. It doesn't provide more or less control, just more consistent uniform steps.

Have any proof that they were voiced for pedal steel? Curious...

[talbany]

Btw. while we're on this I'll add

My experience w/002's filters (before I modified it)
It seemed clear to me the filters in 002 were setup for more than just 6 string electrics.. It was obvious that a few lo filter settings were there for Bass guitar or for pedal steel. A friend Robbie Flint who plays steel with Alan Jackson used some of these settings and the amp sounded fine. There were also a few settings there that sounded fine for guitar and if I played Steel or Bass or Leslie I would have left the 002 filters in. So IMO the amp was more versatile with its original 002 filters.
So the question is not better or worse it's what instrument your playing and what cabinet it's running through

Martin's array is centered better for 6 string electrics and I rarely touch them.... IMO

Tony

It seems clear that the Low filter was HADs attempt at a Audio taper control. Martin's S taper configuration does the exact same thing except it's more consistent.

Not exactly?.. #002's IIRC had a wider frequency range and was less uniform.. 390k/39k on Bass and 150P/.01 on Treble side

Martins was narrower and more uniform (Treble side) 150p/4n7 and 100k/121k on Bass side

It doesn't provide more or less control, just more consistent uniform steps.

The word I used was "versatile" not "control"

Have any proof that they were voiced for pedal steel? Curious...

No I don't have a note from Dumble saying he voiced a setting on his filters for Pedal Steel?
I do have a really good Steel players opinion though

Tony

[Bombacaototal]

Just my 2 cents to my ears there was an audible difference between the inductor in the circuit and having it bypassed (although more towards subtle).

The low filter on 004 is almost useless as you only start hearing the effect of the filter almost all the way up. But that said, how the filter is configured, it really voices the amp to that nasal SSS tone (002 filter similarly).

I am sure Martin's is a more optimised version and I am curious to try it on a next amp, but I am wondering if it will change the original voice of the amp. Only a side by side or A/B will answer this question...

[rccolgan]

I spent the last couple days drawing SSS #002 in LTSpice for my own education and anyone that wants to check it out. FWIW, I'm seeing an effect now with the inductor that I have not seen previously with stripped-down simulations I've done.

I made the files available in the "Dumble Files" section since that felt appropriate. https://ampgarage.com/forum/viewtopic.p ... 41#p411041

My hope is we can use what I started to get a good representation of what's going on. I'm not an expert in LTSpice so any assistance is appreciated with the simulation. (I believe I've got it 96% complete)
-Ryan

(Update: deleting files as there was an error in my schematic)

[martin manning]

FWIW, I'm seeing an effect now with the inductor that I have not seen previously with stripped-down simulations I've done.

See my comment in the SSS thread about the missing 100k resistor.

[Oddvar R]

I spent the last couple days drawing SSS #002 in LTSpice for my own education and anyone that wants to check it out. FWIW, I'm seeing an effect now with the inductor that I have not seen previously with stripped-down simulations I've done.

I made the files available in the "Dumble Files" section since that felt appropriate. https://ampgarage.com/forum/viewtopic.p ... 41#p411041

My hope is we can use what I started to get a good representation of what's going on. I'm not an expert in LTSpice so any assistance is appreciated with the simulation. (I believe I've got it 96% complete)
-Ryan

(Update: deleting files as there was an error in my schematic)

Hi. I have some trouble reading your "Raw" file in the zip folder. What codec is needed? (I tried different apps, Win 10.)

[rccolgan]

I spent the last couple days drawing SSS #002 in LTSpice for my own education and anyone that wants to check it out. FWIW, I'm seeing an effect now with the inductor that I have not seen previously with stripped-down simulations I've done.

I made the files available in the "Dumble Files" section since that felt appropriate. https://ampgarage.com/forum/viewtopic.p ... 41#p411041

My hope is we can use what I started to get a good representation of what's going on. I'm not an expert in LTSpice so any assistance is appreciated with the simulation. (I believe I've got it 96% complete)
-Ryan

(Update: deleting files as there was an error in my schematic)

Hi. I have some trouble reading your "Raw" file in the zip folder. What codec is needed? (I tried different apps, Win 10.)

I believe that's a LTSpice file that's generated when the simulation runs. You're more interested in loading SSS No 002.asc into LTSpice. Windows version of LTSpice is far superior to the native Mac version.

[martin manning]

That's correct. I think most people just want to see a schematic and a layout in a viewable format.