vigilante398
Authorized Vendor
Looks like the PCBs should ship sometime this weekend, so I'll likely see them toward the end of next week. I'll start a new thread as soon as I have a working prototype.
Echo Foxtrot - yet another simple tube preamp (coming soon)
- Thread starter vigilante398
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Silver Blues
Well-known member
You are not good for my wallet, my friend.
vigilante398
Authorized Vendor
jimilee
Well-known member
This
You are not good for my wallet, my friend.
vigilante398
Authorized Vendor
Prototype PCBs came in yesterday, just waiting on a couple parts to get one finished up and tested. Hopefully have some news for you all soon.
vigilante398
Authorized Vendor
Finished up the prototype today, it sounds fabulous. It's basically everything Echo Foxtrot is but a little more flexible, I really like how Matchless did the tone control with the rotary on this one.
The output is hotter than I typically like pedals to be, so I plan to put a dropping resistor on the output. Also a couple parts have footprints that don't fit as well (one too small, a handful too big) as I expected them to, but that's obviously an easy fix. So a couple quick tweaks and I'll spin a v1 board and let everyone know when they're ready. In the meantime I'll be removing Echo Foxtrot from the shop tonight, it's going to be replaced by the Diplomat.
The output is hotter than I typically like pedals to be, so I plan to put a dropping resistor on the output. Also a couple parts have footprints that don't fit as well (one too small, a handful too big) as I expected them to, but that's obviously an easy fix. So a couple quick tweaks and I'll spin a v1 board and let everyone know when they're ready. In the meantime I'll be removing Echo Foxtrot from the shop tonight, it's going to be replaced by the Diplomat.
Bricksnbeatles
Member known well
Any particular reason for having the led behind the tube instead of in the middle of the socket?
vigilante398
Authorized Vendor
Yup, a few reasons. First and foremost, it's easier to install and swap out if you need to change fir any reason. Second, there's only room for a 3mm LED under the socket, you would have to drill it out if you want to use a 5mm, which makes it impossible for anyone using ceramic sockets. Also on some tubes (including EF86) the inner structure of the tube blocks the light, and putting the LED behind it instead of under it helps the light shine through more visibly.
I used to put the LED under the socket, but it only took three or four fried LEDs to make me realize that it wasn't ideal from a repairability perspective.
Nathan -- are you using this switch for the tone control?
vigilante398
Authorized Vendor
Yup, that's the one. Also purchasable from Mouser, StompboxParts, and PedalPCB (when he can keep them in stock, I imagine they sell out a lot due to Arachnid). The Matchless actually uses a 6-position switch, but I added a couple extra values and used an 8 position. Partially because 8-position switches are easier to find, and partially because I wanted to have some options that made it more suitable for use on bass.
ooooh... think I'll mate it to that 60w power amp board then feed in to this pair of Sony 250w/10in er's I have.....
Arachinid and similar fv1 based effects.. seen a couple peeps make a variant stage phaser with it. this going to be a standard 9v box or does it have a little leeway?
vigilante398
Authorized Vendor
The plan is for it to be a 9V box, but the main limiting factor is going to be L7806. The EF86 heater has to have a 6-ish volt supply and it will pull around 200mA. The higher the input voltage, the hotter that L7806 is going to get, and if you get too hot it will go into thermal shutdown. Max input voltage for the NE555 is 16V, so depending on how hot that L7806 gets you have wiggle room everywhere else.
vigilante398
Authorized Vendor
The only parts change I'm planning on this one is the addition of a resistor, but I plan for it to be a common value, likely 220k or 470k. The only other thing that's going to change before release is footprints, namely the 4n7, 2n2, and 1n HV cap footprints are going to use the same size footprint as the 47n so they can scoot closer together, and the 390p footprint for some reason needs to get way bigger. I don't understand why my 390p cap is so much bigger than my 680p cap for the same voltage rating, but it is what it is.
vigilante398
Authorized Vendor
Nope, I have an A1M on this one.
jhaneyzz
Well-known member
The LED placement works really well, especially if you put some crinkled up aluminum tape on the back cover.
Feral Feline
Well-known member
Aluminum tape... 
I know a Juicy Fruit gum-wrapper when I see one.
I know a Juicy Fruit gum-wrapper when I see one.
