Death by Audio - Fuzz War  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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gena_p1
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Post by gena_p1 »

may be guts were some kind like engle530 on official engl site?

This post started "20 Jun 2008, 15:36 ", and we have no new gut shots or any measurements of original pedal sense that time.

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the_ungod
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Post by the_ungod »

Any news?!

Is there someone working on this?!

Cheers

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headless
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Post by headless »

Hey guys, I just got a Fuzz War in the mail and it's fairly different to the schematic.

I'll post Gut Shots up as well, only has 4 transistors and has 100nf caps not 680nf

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destro
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Post by destro »

Cool...

One of the few on my failed builds list. Interested to see the difference in schematics.

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papercutnoise
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Post by papercutnoise »

Interested to see the new guts and schematics too. Especially seeing as DBA appear to have gotten their shit a bit more together recently

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Post by the_ungod »

headless wrote:Hey guys, I just got a Fuzz War in the mail and it's fairly different to the schematic.

I'll post Gut Shots up as well, only has 4 transistors and has 100nf caps not 680nf
We're waiting!lol

:popcorn:

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headless
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Post by headless »

http://www.mediafire.com/?vtm2td43arhh4lw

Didn't want to reduce their size at all, plus this way you don't have to load huge photos if you don't want to.
All the caps that look alike are the same value, I've labeled the different values on the component side pic. All of the pots are B100K, Diodes are germanium, don't think they're 1n34as though. Probably doesn't matter too much. Electro cap is 100µF 50V.

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MicMicMan
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Post by MicMicMan »

this one looks much cleaner than the previous version, but still i can't believe there is such a little amount of solder on pots and switches.

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Emanuele
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Post by Emanuele »

So wich one is the good one, the one with too many transistors or the one with just four??

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Post by the_ungod »

any news?!

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Post by ShortScaleMike »

It's a horrible pedal, just build something else. Literally anything is better.

Or stick a load of misbiased booster stages into one another. Same thing.

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Glass_Hero
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my favorite amplifier: My Glass Hero Amplification
Completed builds: 1973 Orange Graphic 120 head
Fender Champ clone head
custom Pentode input single channel 20 watt head
custom "plexi" 5 watt single ended head
custom Pentode input single channel ~2 watt combo (smaller version of my 20watt)
( i build amps and pedals )

pedal clones
Pro Co Rat
Univox SuperFuzz
Sonic Edge J&J Overdrive
Interfax Harmonic Percolator
EHX Electric Mistress
EHX Big Muff PI
EHX Big Muff into a DBA Fuzz War
Green Ringer
Orange Squeeze
Boss Slow Gear
Death By Audio Sound SAW
Death By Audio Armageddon
Death By Audio Fuzz War
MXR Phase 90
EA Tremolo
TS 808
another TS808 modded out for bass
various loop, boost, kill, stutter, feedback and signal pad stompboxes

pedal modds
big muff clipping modds and internal feedback loops w/ LDRs
EHX POG exp pedal modd
VOX 847 wah modds (expression pedals should be expressive)
Cry Baby Modds
BOSS XT-2 modds


this list is tragically outdated..
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Post by Glass_Hero »

sure we could all just sit around and build tube screamer clones.. that's what this world needs is more tube screamers..

i have the pics from the 4 transistor model, i'll try and get a trace done this weekend..the first stage of the 4 transistor fuzz war has stability in mind..and you if stop being so arrogant about a 'misbiased' stage.. Do you know what the reverse beta of the 2n5089 is? its about 1 so temperature is not going to affect the stage much, neither is many of the stability concerns that most people complain about when they look at a DBA pedal.. Biasing is relative to application.. if you want fizzy, crunched sonic mayhem, or you want clean sparkle..the difference is biasing..

i was in a lecture yesterday on biasing, and we discussed the typical DBA stage.. in the forward active mode it can fall victim to thermal runaway but in the reverse active mode things are different..the beta is close to 1 (as seen from datasheets, for the 2n5088-89 the Br=1.271) so the heat produced in the stage would only slightly increase gain.. you wouldn't reach a thermal runaway point where the gain goes through the roof because the gain is so low on each stage.. hence the reason for stacking two, four or seven stages together..the gain of each stage is multiplied by the next stage.. so when looking at the sound saw schem we see two stages 'misbiased' and both are using 2n5088 transistors.. we know the reverse beta (Br or BR in the datasheets usually listed around the SPICE Model parameters) is low, the stage will only have a gain in the single digits, lets say it has a gain of 4..so with the second stage, biased the same as the first with a stage gain of again assuming 4..we have a total gain from both stages of 4x4=16..in the early fuzz war there is 5 stages stacked up, a tone circuit, then two recovery stages.. if the first 5 stages all have a gain of 4 then we have 4x4x4x4x4 = 1024.. so on the 4 transistor model (which i have been tracing) we see a resistor going from emitter to base, this is a feedback resistor and helps with the stability of the stage.. also the load resistor on each stage has changed from the older 7 transistor model, this will affect gain, so will the changes in the base resistors..if you look close you can see some of the stages have a voltage divider which sets the base voltage..this also helps with circuit stability..


so you can either keep complaining about a design you obvious know little about or you can learn something new about electronics.. the choice is yours.. be inventive and try something different or stick with cloning the tube screamer..

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culturejam
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Post by culturejam »

That's a very interesting analysis. :thumbsup

I only have an English degree and my electronics knowledge is relatively quite poor, but let me see if I have this right:

The idea behind the Fuzz War is to cascade several low-gain, temperature-stable amplifier stages to arrive, ultimately, at a high-gain fuzz?

Also, is thermal runaway a problem in more conventional fuzz circuits?

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bubstance
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Post by bubstance »

If anyone with a 4 transistor Fuzz War could check something, I'd be very grateful. There's a mystery resistor tied to a 100R and one lug of the trimmer... in the pictures provided by headless I can see 3 of the bands (the last three; black, red, gold) but the first band is completely obscured by the battery leads. I'd guess it's either 1K or 2K, but any info would be much appreciated.
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Post by RnFR »

I hate tube screamers. and I want to go to this school where you sit around and analyze fuzzbox gain stages. thanks for the explanation.
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Glass_Hero
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Posts: 114
Joined: 31 Jan 2011, 03:02
my favorite amplifier: My Glass Hero Amplification
Completed builds: 1973 Orange Graphic 120 head
Fender Champ clone head
custom Pentode input single channel 20 watt head
custom "plexi" 5 watt single ended head
custom Pentode input single channel ~2 watt combo (smaller version of my 20watt)
( i build amps and pedals )

pedal clones
Pro Co Rat
Univox SuperFuzz
Sonic Edge J&J Overdrive
Interfax Harmonic Percolator
EHX Electric Mistress
EHX Big Muff PI
EHX Big Muff into a DBA Fuzz War
Green Ringer
Orange Squeeze
Boss Slow Gear
Death By Audio Sound SAW
Death By Audio Armageddon
Death By Audio Fuzz War
MXR Phase 90
EA Tremolo
TS 808
another TS808 modded out for bass
various loop, boost, kill, stutter, feedback and signal pad stompboxes

pedal modds
big muff clipping modds and internal feedback loops w/ LDRs
EHX POG exp pedal modd
VOX 847 wah modds (expression pedals should be expressive)
Cry Baby Modds
BOSS XT-2 modds


this list is tragically outdated..
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Post by Glass_Hero »

culturejam wrote:That's a very interesting analysis. :thumbsup

I only have an English degree and my electronics knowledge is relatively quite poor, but let me see if I have this right:

The idea behind the Fuzz War is to cascade several low-gain, temperature-stable amplifier stages to arrive, ultimately, at a high-gain fuzz?

Also, is thermal runaway a problem in more conventional fuzz circuits?
thermal runaway affects Germanium device more than silicon.. take an old germanium fuzz face and set it on a hotplate.. the gain keeps increasing with the increasing temperature..this might sound fun but it can lead to some wild results and could work well for a noisy fuzzbox, or something..but would not work well in a laser used for eye surgery..

the early fuzz war designs (which we have seen on here before) are slightly temperature un-stable (there is no resistor applying feedback to the device)..The feedback resistor 'feels' the voltage applied to the emitter (in this case) and sends some of that back to the base..so if the emitter voltage rises the base voltage rises too.. this keeps the stage stable and within 'proper' biasing.. but stability is also relative..if you wanted to design to military/aerospace standards then you would need a highly stable circuit independent of device (transistor/opamp) parameters, like the beta, Ico, Vbe (which are all effected by temperature).. But in these designs beta (the transistors forward gain) is not used, the reverse beta is..and since this a really low number the temperature stability would not be such an issue.. the newer model (the 4 transistor circuit) uses more stage gain and more stability per stage to get the high gain fuzz tone it has..

stage gains are multiplied by the gain of the next stage..and the next one and the next one..to give a total gain for the circuit.. say you have 1mV of signal at the input..the first stage has a gain of 4..so you have 4mV at that stages output..the next stage has a gain of 4 so with an input signal of 4mV you would have 16mV of signal at that stages output..etc.. so after 5 stages with a gain of 4 that 1mV signal would be somewhere around 1Volt

sorry if i sound like im ranting.. i just am rather annoyed with people that would rather discredit a design because they dont understand whats happening.. Im sorry not every circuit can be a tube screamer..

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Glass_Hero
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Posts: 114
Joined: 31 Jan 2011, 03:02
my favorite amplifier: My Glass Hero Amplification
Completed builds: 1973 Orange Graphic 120 head
Fender Champ clone head
custom Pentode input single channel 20 watt head
custom "plexi" 5 watt single ended head
custom Pentode input single channel ~2 watt combo (smaller version of my 20watt)
( i build amps and pedals )

pedal clones
Pro Co Rat
Univox SuperFuzz
Sonic Edge J&J Overdrive
Interfax Harmonic Percolator
EHX Electric Mistress
EHX Big Muff PI
EHX Big Muff into a DBA Fuzz War
Green Ringer
Orange Squeeze
Boss Slow Gear
Death By Audio Sound SAW
Death By Audio Armageddon
Death By Audio Fuzz War
MXR Phase 90
EA Tremolo
TS 808
another TS808 modded out for bass
various loop, boost, kill, stutter, feedback and signal pad stompboxes

pedal modds
big muff clipping modds and internal feedback loops w/ LDRs
EHX POG exp pedal modd
VOX 847 wah modds (expression pedals should be expressive)
Cry Baby Modds
BOSS XT-2 modds


this list is tragically outdated..
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Post by Glass_Hero »

RnFR wrote:I hate tube screamers. and I want to go to this school where you sit around and analyze fuzzbox gain stages. thanks for the explanation.
once i got my professor to spend half a lecture on the harmonic percolator.. you're welcome..

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culturejam
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Post by culturejam »

Glass_Hero wrote:sorry if i sound like im ranting.. i just am rather annoyed with people that would rather discredit a design because they dont understand whats happening.. Im sorry not every circuit can be a tube screamer..
You don't sound like you are ranting (to me). What it sounds like is that you are trying to find a way to explain why DBA might have done what they did.

If the concern is temperature stability, and if a good way to do that is to get the gain so low that stability isn't an issue .... wouldn't an equally effective solution be to adjust the emitter and collector resistance to set the gain at just above unity?

In my admittedly uneducated piddlings with common emitter and collector amps, runaway gain isn't a problem with modern silicon BJTs at the relatively low voltages I normally work with (<18v). I don't work on NASA shit. But I agree that a great way to build up high gain is it do it over several lower-gain stages. Good high-gain tube amps are done this way as well (as I'm sure you're already well aware).

Based on the overall build quality and level of physical engineering of the pedals that DBA sells (historically especially), I suspect that they arrived at the "reverse beta" method quite by accident whilst fucking around with parts on a breadboard. I may well be totally wrong on that, and perhaps it is unfair and erroneous to draw a conclusion about electronic engineering based on displays of mechanical engineering. It just seems to me that if you are approaching fuzz circuit design on the level of an EE, you'd also care about how that design was built (especially something for sale and use on the road). But I get the impression that nobody at DBA is thinking about this stuff on the high level that you are. Again, maybe I am vastly underestimating these guys' DC electronics chops.

Nobody can judge what is a good sound for someone else. But I do reserve the right to criticize their build quality and construction methods. Or perhaps I'm just not smart enough to realize how brilliant duct tape is? :blackeye

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ShortScaleMike
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Post by ShortScaleMike »

Well consider me schooled! My frustration with this pedal came from building one and struggling manfully to get anything decent out of it without extensive changes. Maybe I missed something stupid.

I appreciate all your responses and the tech insight.

I'm not a fan of the Tubescreamer though, so count me out there.

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culturejam
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Post by culturejam »

So I just googled "reverse beta" to see if I could do some reading on the topic. First search result:
http://www.muzique.com/lab/reverse.htm
However, the most interesting effect is when this reverse booster circuit is driven into clipping - it clips in a matter totally unlike that of the basic common emitter circuit! The overdriven reverse booster generates a mess of harmonics different from other clipping circuits and configurations.

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