@bigo
Forum Replies Created
-
Posts
-
I recently purchased some AC127’s from Small Bear and all had leakage <300 according to my DCA55.
Using a trimpot for the Q1 bias on the Vox TB build, a value of 14.6K was found to set the Q1 collector voltage to -0.7V. Replacing the trimmer with a 15K resistor provided a Q1 collector voltage to -0.68V, so I suppose a 15K resistor instead of the trimpot might suffice. The Vox TB schematic uses a 10K resistor on the collector side of Q1, which provided a Q1 collector voltage of -0.8V, and I suppose this would be OK. But I am thinking about leaving the trimmer on the collector side of Q1 so I can first adjust the Q1 collector voltage to the ideal -0.7V and then adjust by ear after that.
That looks really nice. I have been thinking of building a neckbeard with AC127 Transistors (NPN) I have, probably a year or two in the future as I have several planned projects in the future. I have an actual Keeley Fuzzbender and it is a great pedal.
Currently I am working on a Vox Tonebender based off the PUFF. I have breadboarded it and construction will start tomorrow. I got delayed by babysitting our 8 mo. old grandchild for 10 days and who happened to be sick with daycare kiddy crud. My wife and then inherited it from her and have been sick nearly two weeks. Then a couple of days ago we had to contend with Ian, being hit with the northern eyewall having 120+ mph winds. Fortunately we lost only a couple of screen panels from our pool cage and a couple of roof tiles. The worst part was being without internet for 2.5 days both from Comcast and Verizon, who apparently share the same infrastructure as we found out.
I dialed in the “correct” or optimal collector voltages on Q1 and Q2 by using trimpots. I will keep a trimpot for the 85 HFE Q1 to adjust as I see fit and the Q2 bias will be an external bias. Breadboarded it sounds pretty good and different than a FF. Probably because the input cap is 220n instead of the FF 2.2u input cap.
I still have a Ge Hornby Skewes treble booster to make (breadboarded as well), a PURP, Colortone OD, Llama, Harmonic Percolator, TB MK3, Bosstone Fuzz and Fuzzrite (actual simple circuit – not the American fuzz version). It sounds pretty nasty when breadboarding it and using matched 170 HFE 2n3904 transistors.
Re: THANKS EVERYONE.MY FUZZ BXXX OUTPUT IS WELL ABOVE UNITY.SOUNDS GREAT JUST NOT AS FUZZY AS I THOUGHT IT WOULD BE,unique sound love it in my distorted channel.
Tommy Bolin used it more like a treble booster with everything maxed out. It really does not get real fuzzy like a Fuzzrite does. More like a booster with some distortion.
As Barry points out, different circuits have different volume outputs. A Distortion+ has difficulty attaining unity gain when maxed out. It is the nature of the beast.
I use one of these little handy dandy testers as well for testing components to confirm approximate values and identification. I think it cost me $20.
I don’t use it for more critical measurements of transistors, diodes, etc. Instead I use a DCA-55 to get more reliable measurements. But for quick identification purposes, it is a great little tool.
Returned from the road. Pics of the rotated switch pedal. Note the wires “wrapping” around the switch. This was my own mod for this pedal which was supplied with 3 different value input caps. I said – why waste them?
Re: Moriearty – your switch query is correct. When the toggle bat is to one side, the opposite side lugs are the lugs actuated (connected).
Yes. I found this out the hard way several years ago, so the switch parameters didn’t match my artwork on the enclosure. Fortunately I left enough wire slack so I could rotate the switch 180 degrees and problem solved!
Thanks for sharing your story, Barry. I would have given my left arm to meet those guitarists!
I’ve been a Maiden fan since their Killers album came (with first lead singer Paul D’Anno). The radio station I listened to at the time in 1980 (the famed WMMS in Cleveland) had a show on at 11 PM called Grand Jury of Rock and Roll where they played 30 minutes of one band vs 30 minutes of another. The top vote getter went on to the next round. I remember Maiden’s debut on the show and listened to the show until they were picked the winner!
Many 60’s and 70’s guitarists ran treble boosters into their amps to get them to distort. The Sabotage Drive PCB is a version of this as Tony Iommi used his Rangemaster into a Laney Supergroup. Ritchie Blackmore, Brian May and Rory Gallagher all used a treble booster into an AC30. Back then there were no distortion pedals or gain controls on amps. You did what you had to do to get distortion from your amp.
Randy Rhodes sound is basically a MXR Distortion+ along with a 10 band EQ pedal into a Marshall amp. I have all the settings I found a few years ago on a spreadsheet. If you dial in those settings – you get a close facsimile to the Randy Rhodes sound. By the way, in the early 80’s Glen Tipton of Judas Priest was using a MXR Distortion+ while Downing stayed with the RM, at least from what I read. You never know what is truly accurate or not.
I think it depends upon the tolerance of the caps. That is +/- percent. If the tolerance is pretty tight – that is 5 percent or less, I don’t think I would be worried about it. But don’t quote me on it.
Yes, Barry I will try to help out to the best of my abilities when I can, but I am more limited in my abilities than many other true experts here.
I too have been going through some issues as well. I can’t play guitar much now due to a chronic wrist condition that gives me a lot of pain in my fretting wrist/hand (De Quervains tenosynovitis). I am due to get a second corticosteroid injection this Monday. If it doesn’t cure it, I will be in for surgery, which I am trying to avoid. I also had a recent ER visit for a kidney stone. Never had one before but I pretty much knew what it was – severe unrelenting right lower quadrant and flank pain and since I had an appendectomy years ago an appendicitis was not in the differential diagnosis. Also been spending a lot of childcare duties with a 4-5 month old (6 weeks in the last 2 months) due to various issues including a death in the family. I am completely exhausted as the grandchild is much more work than my two children ever were. It is hell getting old and definitely not for sissies.
I have not had time t work on my current pedal project in several weeks, but glance at the board fairly often to see if I can help out in any way. I think there are really good people who contribute to this board and should have your back.
I don’t think the transistor change is going to make much of a difference. I tried different transistors and found that higher gain transistors of around 400 hfe or greater worked better.
Pink Jimi Photon stated that the diode should not make that much of a difference. Look up the thread on “zener diode question” and you will have a more full explanation.
The links on the old site for the actual build documents (Guitarpcb.webs.com) don’t lead anywhere. However, on the old site clicking on Forums > Layout Gallery > D’Lay v2 (page 2) might provide you with some information.
You may have to ask Barry where to find older guides, unless the current guide is not that difficult from the old versions.
Cybercrow, that is a good tip, which I employ fairly often. If I think there may be a clearance problem like this, I have some plastic duck tape I use to tape to the inside of the bottom plate of the enclosure.
I have started making wiring diagrams for most of my recent pedal builds since jack locations can differ from pedal to pedal depending upon the drill template used for the particular enclosure. Plus some of the input jacks I have are different configurations. Making the diagram helps to prevent mistakes. Due to the tight constraints caused by the top mounted jacks and location of the LED of my Supa build, I had a grounding issue with the input jack (one of the lugs was touching the back of the pot). After I diagnosed it, I fixed the problem by rotating the input jack slightly and the pedal worked fine. Lately, I have resorted to testing each component before soldering it to the board as well as continuity testing as the build progresses. This makes it for slow building but much less of a chance of a problem once built. Below is my wiring diagram for the Supa with top mounted jacks.
The key is turning the stab (stability) control all the way up. Volume doesn’t have to be up very far. As a matter of fact, for my build named the Industry Fuzz, it is one freaking loud pedal. With the volume about up a quarter it is much louder than bypass to the amp.
I would also make sure the transistors are firmly in their sockets and oriented correctly. At least I can tell the 2N3904 is correctly oriented. It’s hard to tell about the Ge transistors, although the emitter is usually designated by a dot or little tab on the case. However, this is not always true and the marked side can sometimes be the collector. The way I confirm the orientation of the leads is by using a cheap DMM that tells me what the C, B and E leads are.
Thanks Cybercrow. I figured that was the way to do it, but I remembered there was something was previously discussed about possible different pinouts of the newer JFET’s and that some type of adapter might be needed to have the correct orientation.
I guess the next step will be firing it up on the breadboard and adjust the trimmers to get the values given in the instructions.
