Sobbat Pedals

[mictester]

AT LAST!!!

Someone other than me has realised that pedal buffering is a "good idea"TM. Yesterday, I saw inside some of the Sobbat pedals. I don't like their external finish much - it's a bit utilitarian for my taste - but the internal construction is amongst the best I've seen. There's no "mojo" component stupidities - they've just used the right parts for the job. Their choice of components is actually pretty good - they use 4558 for their clipping stages (like me, they like the way they recover from overload), and the rest of the circuits either use TL074, TL072, or NE5532.

The pedals are "quiet" - there's no huge hiss except at really high gain, and they've been sensible enough to spread the gain across devices. They're not scared to add an extra op-amp or two if they want to spread the gain across two stages.

They use gyrator-based tone controls. This approach uses extra op-amps (but, so what? They don't cost much.) - but allows accurate "voicing" that can be musically useful. I don't like the simple tone controls used in most pedals - many have no really useful effect and are just there to add an extra knob to the box - more knobs, more money! The Sobbat approach allows almost any voicing you could think of just by recalculating the frequency and the "Q" of the stage. It's also trivial to add extra controls - you could easily have Bass Mid and Top, all within the guitar's range, or if you wanted to get really silly, you could have lots of filters at ½ octave spacing, like a graphic equaliser!

These are well thought-out. They're nothing revolutionary in design, but they're pretty much what I've been doing for the last few years. They're all buffered, and the sockets and pots are of good quality. They're going to be difficult to break.

Unfortunately, I didn't have a camera with me when I saw them, but the pictures wouldn't tell you much more than I have already. They're not gooped, but the circuits are obvious. If anyone really wants them, I can sketch what they are. The board layouts are obviously carefully considered, and there aren't any "last minute mods" in evidence. The soldering is of a very high standard, and the PCB material they use is superb.

Nice pedals, reasonably priced.

[Dirk_Hendrik]

But everyone knows buffers sound hiddeous!....

Seriously now.
I wonder to which extend this (excellent) approach with gyrators is similat to what the Maxon guys have been doing for years in loads drivepedals. And the new post-Maxon design guys for Hoshino after that.

The DS7 is still perfect example of how to voice a dirt box with a graphic EQ and rearrange that in gyrators:
http://www.ibanez.com/parts/2004_PARTS/ ... DS7-01.pdf

but look at, as an example, the modernfusion as well for a more classic Maxon approach:
http://8bitsindgenug.net/ibanez_mf5.png

[analogguru]

The Boss HM-2 was introduced in 1983 and has a gyrator based tone-control.

analogguru

[Dirk_Hendrik]

Now I was hoping to make a smart reply mentioning the Ibbie SM9...

1984... fail

[mictester]

But everyone knows buffers sound hiddeous!....

Seriously now.
I wonder to which extend this (excellent) approach with gyrators is similat to what the Maxon guys have been doing for years in loads drivepedals. And the new post-Maxon design guys for Hoshino after that.

The DS7 is still perfect example of how to voice a dirt box with a graphic EQ and rearrange that in gyrators:
http://www.ibanez.com/parts/2004_PARTS/ ... DS7-01.pdf

but look at, as an example, the modernfusion as well for a more classic Maxon approach:
http://8bitsindgenug.net/ibanez_mf5.png

You're right - the Maxon pedals mostly used simple transistor gyrators that are really quite limited - the Q can't ever be very high, and there are loading effects due to the need to bias the transistors - so they're quite limited. The Sobbat approach of using additional op-amps is more sensible, more predictable (designing op-amp stages is usually easy compared to transistor ones), and adds little to the cost whilst really improving functionality. I just like the Sobbat philosophy.

Their approach of spreading gain across stages to minimise noise is also to be applauded - we know we can break over LEDs with a single op-amp stage, but it will be noisy. They would use two stages and get a quieter result.

I'd forgotten all about the DS7 - as I recall, it was noisy, but it went some way to doing the distortion with gyrator filter idea.

My point wasn't that the Sobbat pedals were unique - they're just a better way of doing things, and I like their design approach. Their build quality is superb, and they produce products that will stand up to being gigged.

[analogguru]

The Sobbat approach of using additional op-amps is more sensible, more predictable (designing op-amp stages is usually easy compared to transistor ones), and adds little to the cost whilst really improving functionality. I just like the Sobbat philosophy.

It´s not the "Sobbat approach" because the 1983 Boss HM-2 already uses op-amps as gyrators - not transistors. Op-amps as gyrators can be found in the DOD FX56, FX58, FX59, FX66, FX69, FX70 and many other pedals.

analogguru

[mictester]

The Sobbat approach of using additional op-amps is more sensible, more predictable (designing op-amp stages is usually easy compared to transistor ones), and adds little to the cost whilst really improving functionality. I just like the Sobbat philosophy.

It´s not the "Sobbat approach" because the 1983 Boss HM-2 already uses op-amps as gyrators - not transistors. Op-amps as gyrators can be found in the DOD FX56, FX58, FX59, FX66, FX69, FX70 and many other pedals.

analogguru

Either there's a language misunderstanding, or you're being deliberately obtuse:

The tone control design is the least of it. The use of op-amp gyrators isn't "new" and I didn't say it was - though you're wrong about at least two of the models you list, as the original versions had crude transistor gyrators (at least in their earliest versions).

My approval of the Sobbat approach to design is: using multiple op-amp stages to spread gain (and thereby reduce noise), using better tone control circuits than the usual rubbish, using good quality materials and building up to a specification, rather than down to a price. As I pointed out (and you chose to ignore), there's nothing particularly innovative in their products, just well made, reliable, quality products, sensibly priced. I like their attitude towards design. It's similar to mine! They don't mess around with "mojo" components - they use parts to get the job done well. They don't worry about the idiots that insist on "solid copper true bypass" - they buffer everything, which guarantees good quality performance in all circumstances.

You chose the name "Guru", but sometimes I wonder.....

[analogguru]

Either there's a language misunderstanding, or you're being deliberately obtuse:

I think it will be the language barrier - I am Austrian and we don´t have any kangaroos over here therefore my native language is german.

The tone control design is the least of it.

As far as I remeber I was talking only about the tone control using op-amp as gyrators, and I wanted to be helpfull to find out more about the history. Sorry that I tried.

The use of op-amp gyrators isn't "new" and I didn't say it was - though you're wrong about at least two of the models you list, as the original versions had crude transistor gyrators (at least in their earliest versions).

That´s interesting to me. Could you please be so kind and name those two models and if possible post a schematic of those earliest versions without any opamp as gyrator ?

Correct me please, when I am wrong:

My approval of the Sobbat approach to design is: using multiple op-amp stages to spread gain (and thereby reduce noise),....

When I look at my schematic of the Sobbat DB-3 I can see:
A non-inverting buffer (gain=1) followed by a non-inverting buffer (gain=1) followed by a single amplifier stage (maximum gain = 310) followed by a LED-clipper stage....

.... using better tone control circuits than the usual rubbish,.....

...followed by a tube-screamer tone control, a volume pot and another transistor buffer (gain = 1).

....they buffer everything, .....

...they even buffer a buffer.

I like their attitude towards design. It's similar to mine!

Are you buffering a buffer too ?

You chose the name "Guru", but sometimes I wonder.....

Don´t worry, be happy !

analogguru

[mictester]

Either there's a language misunderstanding, or you're being deliberately obtuse:

I think it will be the language barrier - I am Austrian and we don´t have any kangaroos over here therefore my native language is german.

The tone control design is the least of it.

As far as I remeber I was talking only about the tone control using op-amp as gyrators, and I wanted to be helpfull to find out more about the history. Sorry that I tried.

The use of op-amp gyrators isn't "new" and I didn't say it was - though you're wrong about at least two of the models you list, as the original versions had crude transistor gyrators (at least in their earliest versions).

That´s interesting to me. Could you please be so kind and name those two models and if possible post a schematic of those earliest versions without any opamp as gyrator ?

Correct me please, when I am wrong:

My approval of the Sobbat approach to design is: using multiple op-amp stages to spread gain (and thereby reduce noise),....

When I look at my schematic of the Sobbat DB-3 I can see:
A non-inverting buffer (gain=1) followed by a non-inverting buffer (gain=1) followed by a single amplifier stage (maximum gain = 310) followed by a LED-clipper stage....

.... using better tone control circuits than the usual rubbish,.....

...followed by a tube-screamer tone control, a volume pot and another transistor buffer (gain = 1).

....they buffer everything, .....

I haven't seen the DB3. I was looking at the DB1 and DB2, and I like the way they work. Buffering a buffer? Not in the ones I saw. They have a unity gain stage at the input which in bypass goes to the output socket, giving a < 1k output impedance. In effect mode, the final stage of the effect strip has a similar output configuration to the input buffer, so the output impedance stays the same.

I also saw a phaser - OTA phase stages driven by a fairly complex LFO - it certainly wasn't a simple triangle waveform, and it also did pretty good vibrato. Again, it didn't hiss, and the construction quality was excellent.

If the DB3 is as you describe, then I'm disappointed.

As far as the old Japanese stuff is concerned - I'll find all my old factory schematics (from when I worked over there as a designer) and get them scanned and up on the website.


As far as the language barrier is concerned - the only kangaroos in this city are in the Artis Zoo (I'm in Amsterdam tonight, visiting relatives and working here tomorrow morning, then back to London City airport and a meeting in the Docklands at 3pm). I'm British, normally living in North London, but my ancestors were Austrian (one grandfather) and Dutch (one grandfather and one grandmother) and the last grandmother was a Scot who lived most of her life in Northern Ireland (and she married the Austrian!)

My wife and I had a week in Vienna at the beginning of December last year - it was the first time she had been there, and we did a lot of sight-seeing. If I had to live in mainland Europe, Vienna would be high on my list of choices. We're going to Austria again in the summer, to visit some relatives and to see more of the country.

[mictester]

People - watch out for the dodgy links appearing from various spurious "new users". They're from spambots, and the pages the links go to will infect Windows machines.

[Greg]

People - watch out for the dodgy links appearing from various spurious "new users". They're from spambots, and the pages the links go to will infect Windows machines.

Yes thanks mictester.. if you see any folks, please report them with the Report Button on the right..