tested some NPN's in the Muff......kinda surprised

[plexi12000]

so i got a pile of different npn's to try for the muffin.  what the heck....see what they sound like. 

i was kinda surprised. the higher the DC gain was.....the worse it sounded.  the higher the hfe....the thinner it got and less gain/distortion, etc.

the ones between 300 and about 600 sounded great.  any Q's that had hfe above that, sounded dreadful.   including the 5088.

just to share my oppinion......the BC549-BTA's are VERY nice!  in fact....they sound virtually the same as the 2n5133's i have.  the 5133's i have, are all around 360. 

the 549's are around 430.  real nice transistor.  i have about 4 or 5 more to try out.

[Gus]

Did you measure the DC voltage of the transistors as you changed them?
Measure the power supply voltage or battery
measure the DC voltage from transistor legs to ground

[bool]

You were looking at BC549B essentially.

[antonis]

the higher the DC gain was.....the worse it sounded.  the higher the hfe....the thinner it got and less gain/distortion,

I'm not sure that I follow you...

DC gain & hFE are interchageable terms --> (beta) β(dc)

hFE (in italics) is β(ac) which formaly express the common-emitter forward-current amplification of the device..

The levels of β(ac) and β(dc) are quite equal in their magnitudes and therefore become interchangeable (at least at lower levels of I(ceo)..)


P.S.
From personal experience, a quartet of 2N3904 form a "quite" Big Muff, 2N5088 form a "fair" one and MPSA18 form an "ugly" fuzz..

[GibsonGM]

As much as they call for specific transistors in a lot of these builds, from muff to FF, I seem to find myself reaching for the 3904, and enjoying the results 

I think it's pretty commonly found that high beta does NOT necessarily equal 'great tone'.   I think of it as 'swamping' the circuit...just flooding it.  Poor analogy, but it works for me.  The real thing is probably over-compression, no headroom and the like.

Rather than a nice, orderly flow of current thru the 'pipes', a too-high beta acts like a deluge, and all the subtle niceness is swept away....plus, the Q's might load each other with crappy results...

[digi2t]

As much as they call for specific transistors in a lot of these builds, from muff to FF, I seem to find myself reaching for the 3904, and enjoying the results 

I think it's pretty commonly found that high beta does NOT necessarily equal 'great tone'.   I think of it as 'swamping' the circuit...just flooding it.  Poor analogy, but it works for me.  The real thing is probably over-compression, no headroom and the like.

Rather than a nice, orderly flow of current thru the 'pipes', a too-high beta acts like a deluge, and all the subtle niceness is swept away....plus, the Q's might load each other with crappy results...

Hey, that's a great analogy. The visual is perfect for a non-com like me. I must remember that one. Thanks!

[bloxstompboxes]

In my first muff I used 2N5550s for the hell of it and to be different. I rather like it better than the 2N5088s I have used in subsequent builds.

[PRR]

It's all relative. The resistors must be scaled for the transistors they bias. Odds are that if you re-engineered the bias for the hi-gain transistors you could find a less-worse sound, maybe a fine sound.

I have a tractor with modest Power. The go-pedal has lots of leverage so I can call-up my few Horses easily. If I replaced the mild 3-banger engine with say a GMC V-12, but kept the same go-pedal linkage, if I barely touched the pedal the tractor would flip over. I'd want to change the linkage to suit the increased engine power.

[plexi12000]

It's all relative. The resistors must be scaled for the transistors they bias. Odds are that if you re-engineered the bias for the hi-gain transistors you could find a less-worse sound, maybe a fine sound.

I have a tractor with modest Power. The go-pedal has lots of leverage so I can call-up my few Horses easily. If I replaced the mild 3-banger engine with say a GMC V-12, but kept the same go-pedal linkage, if I barely touched the pedal the tractor would flip over. I'd want to change the linkage to suit the increased engine power.

PRR-- in other words....if you alter the resistor vaules for each type....each could sound "better"?

[plexi12000]

the higher the DC gain was.....the worse it sounded.  the higher the hfe....the thinner it got and less gain/distortion,

I'm not sure that I follow you...

DC gain & hFE are interchageable terms --> (beta) β(dc)

hFE (in italics) is β(ac) which formaly express the common-emitter forward-current amplification of the device..

The levels of β(ac) and β(dc) are quite equal in their magnitudes and therefore become interchangeable (at least at lower levels of I(ceo)..)


P.S.
From personal experience, a quartet of 2N3904 form a "quite" Big Muff, 2N5088 form a "fair" one and MPSA18 form an "ugly" fuzz..

Thanks for the info.   -- well, i'm here to learn. so i post stuff and ask questions.  that way, people "talk" and "share" knowledge with others.

[brianq]

I've built some Big Muffs with 2n3904,metal can 2n2222's & BC547a & they've all come out sounding great, I think the circuit really likes medium gain trannys, just my 2 cents

[Gus]

Look for the "A Somewhat Different Fuzz" ASDF thread.  I selected values to work with 2n5088 2n5089 transistors.  Read Jimi's posts IIRC he liked it better with 2n5089s listen to the youtube he posted.

I posted before to measure the voltages of the transistors and power supply

[GibsonGM]

PRR-- in other words....if you alter the resistor vaules for each type....each could sound "better"?

You can adjust the values of the resistors to "DO THINGS" to your circuit.  You can alter how much of that gain you are actually using...change the bias point...you can even adjust how much the bias network loads the signal. 

I think Paul is saying that if you tinker with the circuit (with some intelligence behind it), you may be able to bring a 'crap fuzz' back from the edge into something useable by taking these things into consideration.     

So yeah, it's just that simple, BUT you have to know what's going on in order to use the characteristics of the transistor this way

[antonis]

I think Paul is saying that if you tinker with the circuit (with some intelligence behind it), you may be able to bring a 'crap fuzz' back from the edge into something useable by taking these things into consideration.

After all, its just a matter of asking for a kind of "theoretically useless" gain from your amp....

In reality, if we clip a signal by two different beta transistors with exactly the same bias and Rc/Re gain - keeping both in their respective Q point area, so we have only supply headroom clipping - we do NOT take identicaly same waveforms at their outputs...

[GibsonGM]

+1, they won't 'act the same', of course.  But you CAN likely improve things somewhat by coming closer to what the original design intended.  You may not GET the original design sound, but far better than the 'way too hot' thing.   

If you're running the 'too hot' transistor wide open, zero headroom, hard clipping and harsh fuzz resulting...and you throttle it back, I would presume that you will get much more useful, or at least useable, results!   And interesting things will probably result as you shift the operating region.   How interesting?
Don't know - try it out! 

[Gus]

You can work with higher beta hfe devices
Jimi was nice and posted a youtube of the ASDF
http://www.diystompboxes.com/smfforum/index.php?topic=105848.msg955000#msg955000
it has 2N5089s.  It was designed to work with high beta hfe devices

Listen to the video it might not be a fuzz you like but would you have guessed 2N5089s?  Does it sound thin, harsh?

A hint, measure the DC operation points of the transistors, are you close to cutoff or saturation or somewhere in between?  Note bias when it sounds good.

here is another link http://www.diystompboxes.com/pedals/gusFuzzFace.gif
this can work with different hfes beta transistors because of the bias and resistor values selected.  Different transistors will sound different however you can adjust the thinness etc with the bias for the transistors used.  I tend to like beta 200 2N2222s but 2N5088s MPSA18s can sound good in a different way.  This is a good sounding  Fuzz

Have you noticed different BMP schematics have different collector resistors and sometime other component values are changed?

EDIT an link that might helphttp://www.diystompboxes.com/smfforum/index.php?topic=105257.0