Messages

Cool, thx. The JFETs I've got sure look a lot like the genuine Fairchild.

I hadn't been a member over at GuitarPCB, but it looks like a good site. Thx for hipping me to that, too.

Are you a member at GuitarPCB?

http://www.guitarpcb.com/

For the link below to work you need to be a member. (it's free)

Here is some info and pics of fake and genuine Fets.
Scroll down the page.... 

http://www.guitarpcb.com/apps/forums/topics/show/13285269

The "F" is for Fairchild Semiconductors and there's a lot of fakes out there these days.

Buy from reputable sources. 

Yeah, there's no way these are genuine Fairchilds. I didn't realize they used that "F." I'm more familiar w/ their other logo.

Thanks for the info.

Where did you get your jFets from?

Tayda.  They're the same brand (they have a big F on them) as the matched pair I got from GGG (one of which failed).

Gonna have to buy 'em in bulk, as I need 6.  Working on a Maestro PS-1.

Built a P45 clone (Madbean Smoothie) a few yrs ago. At some pt I started asking myself whether it was working right. I knew it was subtler than a P90, but it didn't seem right, so I quit using it.

I'm working on another phaser build, and I thought I'd try matching my own JFETs. (Previously bought matched pair of 2N5458s from GGG.) Built the tagboard Greatly Improved JFET Matcher II, and fooled around testing the few JFETs I had on hand, also measured the ones in my P45/Smoothie.

Though the ones in my Smoothie test OK (~0.740V), one of them doesn't work in the circuit. If I swap it w/ one of the ones I had on hand (that tests similarly) the P45 works like it's supposed to, and like I remember it working. (Also works w/ another pair of 5485s I matched up.)

Is this JFET tester not testing what it should be testing?  Thanks.

Both channels (distortion & boost) work fine. I had wired it w/the boost chan in front of the dist (w/bypass switch for each chan), but noticed that if the boost was on, the distortion gain pot crackled when turned. (Though at a substantially lower level than when that particular channel is active.)

So now I've completely removed the dist section from the signal path, but the same thing occurs. Is this normal? I understand that the gain pot adjusts the transistor bias, but these are two totally separate circuits. Should there be interaction?

Also, If I touch the open input lead of the dist chan, I induce a hum into the boost chan. Is there some leakage here? Again, these are two totally separate circuits.

BTW, if hook up the dist chan, leaving the boost chan disconnected, I don't get the same things happening.

Schematic and layout PDF attached.

I like this pedal, but it can be a little gritty, esp on low notes. And if you add even a 7th to a voicing, trashy, low frequency harmonics appear.  Wondering whether anyone's had any experience reducing some of these qualities w/ different devices (diodes, FETs, etc) in the FB loop.  TIA.

Fuzz,

I'm not thrilled w/ the way their system applies shipping charges during checkout. Somehow it guestimates the size and weight in order to calculate the cost. However, it is possible get a better rate than what the system shows during checkout.

I ordered from them a few weeks ago, and during checkout my 2 cheapest options were UPS Gnd, or UPSPS Priority Mail (med size box), both for over $11 (which was more than 1/3 the cost of the merchandise). But before completing the order I called them, and they said that if the order could fit in the small Priority box, they'd use that, and refund me the $6 difference. (When paying through PayPal I made sure to note this in the message box.) My order did ship in the small box, and (after a few emails) I did get a $6 refund. However, they might only do this if it's requested.

In general, shipping has gotten very expensive. Their quote of $11+ for UPS seemed outrageous. But when I did my own calculation for UPS, the actual cost would have been over $8 (I'd expected it to be $5 and change). And I assume Mammoth is a pretty small outfit, so I don't know what kind of deal, if any, they get from UPS. Priority Mail flat rate seems to be the best choice for many of these smaller shipments. As long as your order fits in the small box, at $5.15 (online price) it's even less than Standard Post. And strangely, 2 small boxes ship for 10.30, while the medium box is $11.30. So you're actually better placing 2 orders!

the only gripe I have with Mammoth is their outrages shipping cost.  I ordered several 1590Bs and 1590As and the shipping cost was about 50% of the total cost.  That was the cheapest ground shipped to California.  Jeeze!!  I ordered the same from tayda, from Thailand, and thier shipping was much cheaper than mammoth's.

I see that you most recent order took a while to ship (or maybe still hasn't). I was going to ask whether the delay seemed to be on their end, or with the shipper.

Could it be that an item was out of stock at the time they pulled your order, so the whole thing was held up?  Do they notify buyers in this case? 

I'm not bashing Blake. He is running a great business.
Im asking if anyone else is having the same slow processing/shipping as I've had the last two orders.
last time it took nearly 2 weeks to make it 50 minutes to my house.
This time I ordered some caps, knobs, & a switch 8 days ago and it hasn't shipped.
Just seems weird.  

I've seen a few threads dealing w/this topic, though I think I've seen only one resolution, which had to do w/ poor solder joints.  Nor have I seen any definitive (i.e. correct) voltage numbers from the 3 transistors.

Originally I used 2N2222s (Which is what the /13 Joy Ride, also a Colorsound knockoff, uses.), but the distortion was awful: very coarse and gritty, and the decay was terrible.

Now I've got BC109s in there, and though they're better, the unit still isn't too good. The distortion is coarse w/ fizz on top.  And though the decay is better, it still isn't smooth; the distortion still cuts off once the signal is low enough.  

I've gone through the board and verified that all my components and values are correct.  Here are my voltage readings for the 3 Qs (with 9.36 battery voltage):

Q1  E 0.45V, B 1.02V, C 1.7V
Q2  E 1.04V, B 1.7V, C 5.36V
Q3  E 0.92V, B 1.56V, C 5.83V

My build is on the board w/ board-mounted pots.
I've attached a short mp3 in case that helps.

Assistance greatly appreciated!