ORPHEUM FUZZ

[Sparky]

Taking a break from Tonebenders and threw together a silicon Orpheum Fuzz.
Yowza......pretty cool.   I think I may like it better than the Fuzzrite. 

[GibsonGM]

Going to post any sound clips by any chance?

[Sparky]

I'd like to post sound clips but don't have the tech right now.

[Gargaman]

This is kind of similar as the Fuzzrite, isn't it? That 22k resistor to ground, blend pot. I've tried a few times to get Fuzzite to sound right. As far as I've been searching this transistor bias method is highly beta dependent. Is 10M collector to base resistor value indicate to what hfe?

[antonis]

Is 10M collector to base resistor value indicate to what hfe?

Let's estimate it..

Supposing power supply mid-point Collector bias, calls for 200μA quiescent current (for 22k Collector resistor)
For about 4V drop across 10M resistor, 400nA Base current is needed..
(leakage current included but considered negligible..)
So, a BJT of h_FE equal to or greater than 500 (at 200μA Collector current and 4.5V Collector - Emitter voltage) should be fine..
(most commercially availaible BJTs specs refer on h_FE for I_C=100μA and V_CE=5Vdc..)

[Mark Hammer]

[mdcmdcmdc]

I have a three-knob version of the orpheum/manny's fuzz sitting here if you're interested in adding the tone knob to yours. Happy to open it up and take some photos of the board.

[Sparky]

This is kind of similar as the Fuzzrite, isn't it? That 22k resistor to ground, blend pot. I've tried a few times to get Fuzzite to sound right. As far as I've been searching this transistor bias method is highly beta dependent. Is 10M collector to base resistor value indicate to what hfe?

[Sparky]

This is kind of similar as the Fuzzrite, isn't it? That 22k resistor to ground, blend pot. I've tried a few times to get Fuzzite to sound right. As far as I've been searching this transistor bias method is highly beta dependent. Is 10M collector to base resistor value indicate to what hfe?

Yup, the Fuzzrite circuit has been difficult for me.....the last one I built  doesn't sound  "correct" to my ears [not enuff  high-end "bite" to it.]    I've also found it's much better to test this circuit with a clean amp that isn't already distorting.   There is also the issue of transistor hfe..... less gain or more gain  ??
I used a 2 meg  [instead of 10 M]  collector-to-base resistor in the Orpheum build and it sounds massive with a good amount of fuzz in the signal.

[Sparky]

I have a three-knob version of the orpheum/manny's fuzz sitting here if you're interested in adding the tone knob to yours. Happy to open it up and take some photos of the board.

Thanx, but I'm going to mess around with the basic circuit for a bit before adding any tone controls.

[Sparky]

  Thanx Mark!   It's great to have all the info in one spot!

[iainpunk]

the FY-2 from Shin-Ei has a hardwired mid scoop but there are mods to vary the scoop depth, like in the picture here. i think its a good way to emphasize that vintage vibe from a fuzz-rite (or almost every fuzz out there) even more.


cheers, Iain

[duck_arse]

I have a three-knob version of the orpheum/manny's fuzz sitting here if you're interested in adding the tone knob to yours. Happy to open it up and take some photos of the board.

we want this anyway. maybe a new thread?

[Sparky]

Build Report So Far ---
  I used the Yaff transistors  [2n2369]
   Used a 2.2 meg for the collector-to-base resistor on Q1.  How does this 2.2M res affect the sound compared to the stock 10Meg ?.
   Substituted  1 uf caps for the .1 caps  so overall this build would sound [I think]  bigger and bassier then stock. 
I guess a completely stock circuit would have more high-end than mine.

[Mark Hammer]

Lift the ground end of the 0.1uf cap coming from the junction of the 100k and 47k feeding the collector of Q2, and see if you like the result.

P.S. Iain, the 50k Scoop pot is overkill. 5-10k will be more than sufficient.

[Sparky]

Lift the ground end of the 0.1uf cap coming from the junction of the 100k and 47k feeding the collector of Q2, and see if you like the result.

P.S. Iain, the 50k Scoop pot is overkill. 5-10k will be more than sufficient.

Thanx for the tip, Mark.   I tried it but seems to add a bit of noise so re-soldered it back in place.
   This circuit [as I modded it ]  is LOUD !    Maybe it's the 1 uf caps pushing more juice through it but it seems too loud as it is.   I played it through a Roland Blues Cube solid state amp with 1-12" speaker with a clean setting and it just boosted too much.

[Mark Hammer]

The midscoop filter in the FY-2 removes much of the level, (although, you know, that's what volume controls are supposed to do).

The .047uf cap in parallel with 100k on the FY-2, provides for more treble.  Or rather, diminishes bass.  Removing it yields more oomph to the tone.

[Halkbi]

Nice chart! But didn't the silicon Fuzzrite also have the 22k R8? I have yet to come across a gutshots of an original that doesn't have it, and it's present in the Catalinbread Fuzzrite (which is supposed to be a proper recreation of the original, based upon NOS units provided by the Moseley family).

[Sparky]

The midscoop filter in the FY-2 removes much of the level, (although, you know, that's what volume controls are supposed to do).

The .047uf cap in parallel with 100k on the FY-2, provides for more treble.  Or rather, diminishes bass.  Removing it yields more oomph to the tone.

Is a stock Fuzzrite way louder then unity??    I don't have any here for comparison and can't remember correctly.  I know that putting the input cap back to stock .1 uf would make some difference but how about the other two .1 caps ?     Replacing those caps may return the circuit back to being a bit more manageable.   I like pedals with a good dose of volume in reserve but this is too overwhelming !   It's also pretty noisy .

[Mark Hammer]

Let me ask you, are you using a logarithmic volume pot or a linear pot?  I ask because way back before we knew any better, back when we thought that 10 watts would be 10 times as loud as 1 watt, it was a common trick for manufacturers of stereo and music amps to use linear volume pots.  The prospective customer would turn the volume up to maybe the 8:00 position, and it would be ungodly loud, leading them to think "Man, if it's THIS loud at that setting, think how loud it will be if I dime it!".  Of course, they'd get home and find it actually wouldn't get all that much louder no matter HOW high they turned it up.

If your volume control makes it hard to dial in something that is just a little louder than bypass level, perhaps the issue might be the volume pot taper.