Echo Foxtrot - yet another simple tube preamp (coming soon)
- Thread starter vigilante398
- Start date
Feral Feline
Well-known member
MichaelW
Well-known member
Hey @vigilante398 did you ever make these available? I don't see them on your website. TIA!
vigilante398
Authorized Vendor
Oh right, nope haven't done that yet. I'll see if I can get the build doc put together in the next couple days (I have a template so it's not hard, just need to plug it in) then get them posted.
MichaelW
Well-known member
Definitely put me down for one. I'm stoked about this!
vigilante398
Authorized Vendor
Alright, finally got the build doc put together, you can take a look at it here.
A couple notes about the build:
A couple notes about the build:
- There are a couple weird resistor values (2k87 and 85k) that are not critical and can be replaced with the closest readily available value (2k7 and 82k) without really affecting the sound.
- YOU HAVE TO USE AN EF86. 12A*7 family tubes WILL NOT WORK in this build. It can be an actual branded EF86 or a Soviet 6Ж32П (6J32P), but it has to be a single pentode, not a dual triode.
- Since this is a single pentode stage it will not overdrive by itself, this is just a clean tube stage that you can either run by itself as a clean preamp, put in front of an amp to use as a clean boost, or run something else in front of it to push the pentode into overdrive.
- I put a link to Antique Electronic Supply for the EF86 tube, but you can generally get them MUCH cheaper on eBay. "Winged C" and Svetlana are common brands for the 6Ж32П, but there are plenty of NOS EF86 available for cheaper than you can get a modern production EF86.
- And something to keep in mind about EF86 in general, they are far more likely than 12AX7 to be microphonic, so it's not a bad idea to pick up some silicone damper rings to throw on your tube to help tame it. Alternatively you can do what I did and buy a huge batch of tubes then sort them for the lowest microphonics
chongmagic
Well-known member
Alright, finally got the build doc put together, you can take a look at it here.
A couple notes about the build:
So with all that in mind, I'll say that it's about as easy of a build as Space Heater, it's a fairly simple circuit and is in the same form factor and will go in the same enclosure. The PCB isn't live on the website yet, but I'll get it up this afternoon and let everyone here know.
- There are a couple weird resistor values (2k87 and 85k) that are not critical and can be replaced with the closest readily available value (2k7 and 82k) without really affecting the sound.
- YOU HAVE TO USE AN EF86. 12A*7 family tubes WILL NOT WORK in this build. It can be an actual branded EF86 or a Soviet 6Ж32П (6J32P), but it has to be a single pentode, not a dual triode.
- Since this is a single pentode stage it will not overdrive by itself, this is just a clean tube stage that you can either run by itself as a clean preamp, put in front of an amp to use as a clean boost, or run something else in front of it to push the pentode into overdrive.
- I put a link to Antique Electronic Supply for the EF86 tube, but you can generally get them MUCH cheaper on eBay. "Winged C" and Svetlana are common brands for the 6Ж32П, but there are plenty of NOS EF86 available for cheaper than you can get a modern production EF86.
- And something to keep in mind about EF86 in general, they are far more likely than 12AX7 to be microphonic, so it's not a bad idea to pick up some silicone damper rings to throw on your tube to help tame it. Alternatively you can do what I did and buy a huge batch of tubes then sort them for the lowest microphonics
Are these in your store now?
vigilante398
Authorized Vendor
vigilante398
Authorized Vendor
I just posted these in the Back In Stock thread, but if anyone wants the drill template for Space Heater/Echo Foxtrot (they use the same template) you can find them with the links below. One of these days I'll actually get them put into the build documents.
drive.google.com
drive.google.com
DIY Space Heater Drill Template.pdf
drive.google.com
TH Space Heater.dxf
drive.google.com
vigilante398
Authorized Vendor
It's just been brought to my attention that the BOM in the build document was missing U2, the L7806 regulator, I'll get that updated. I apologize for the inconvenience.
Bricksnbeatles
Member known well
from what I've read it seems like the 6267 should be less microphonic than the EF86 but otherwise the same- Any thoughts on this?
vigilante398
Authorized Vendor
I don't have any personal experience dealing with the 6267, but looking at the datasheet it certainly looks equivalent. The only place I'm seeing mention of less microphonics is from TAD, but they list their tube as "EF86/6267" and I've personally bought TAD EF86 and had the same microphonics problems with those as with the Winged C 6J32P. The only brand I've found that actually seems to have less microphonics (again in my limited experience) was JJ/Tesla.
Feral Feline
Well-known member
IIRC, I ordered a Telefunk EF86/6267.
When/if it gets here I'll be ordering an Echo Foxtrot.
When/if it gets here I'll be ordering an Echo Foxtrot.
MichaelW
Well-known member
I used the TAD EF86/6267 and don't have any issues with microphonics even with the gain dimed and pushing it with a boost.
I've also been running it with the tone wide open, it seems to get some lovely glassy tones that way.
Ok some very cool combinations since building the Echo Foxtrot.
I've replaced one of the tubes in my Black Eye with a 12AT7 (per @Dan0h) to take the gain down a couple notches.
It's definitely in a more usable (to me) gain range now, but it's also lacking some bottom end by itself.
Running the Echo Foxtrot in front of the Black Eye is the perfect match. Feels like it gives the BE more of that body, warmth and fuller bottom end than by itself.
I built my brother an AC Booster that is a great sounding Vox-ish sounding overdrive. He said it stopped working, so I built him another one. Today I got the "bad" one back......and......there's nothing wrong with it. Heh, works perfectly, not sure what happened in his rig.
But now I too have an AC Booster hahah. Running the Echo Foxtrot in front of the AC Booster also sounds phenomenal.
It's like my own little faux desktop AC30 hahaha.
The Echo Foxtrot definitely has a tonal profile and coloration and I probably won't be using it full time like the Space Heater but so far I'm absolutely loving it! There's lots of cool ways to use it but I'm having a lot of fun boosting other drives with it right now.
I've also been running it with the tone wide open, it seems to get some lovely glassy tones that way.
Ok some very cool combinations since building the Echo Foxtrot.
I've replaced one of the tubes in my Black Eye with a 12AT7 (per @Dan0h) to take the gain down a couple notches.
It's definitely in a more usable (to me) gain range now, but it's also lacking some bottom end by itself.
Running the Echo Foxtrot in front of the Black Eye is the perfect match. Feels like it gives the BE more of that body, warmth and fuller bottom end than by itself.
I built my brother an AC Booster that is a great sounding Vox-ish sounding overdrive. He said it stopped working, so I built him another one. Today I got the "bad" one back......and......there's nothing wrong with it. Heh, works perfectly, not sure what happened in his rig.
But now I too have an AC Booster hahah. Running the Echo Foxtrot in front of the AC Booster also sounds phenomenal.
It's like my own little faux desktop AC30 hahaha.
The Echo Foxtrot definitely has a tonal profile and coloration and I probably won't be using it full time like the Space Heater but so far I'm absolutely loving it! There's lots of cool ways to use it but I'm having a lot of fun boosting other drives with it right now.
Mike McLane
Active member
So Nathan. . . you're a Matchless fan. I've never messed w/ 'em. Does the EFtrot give off that Matchless vibe for you?? If running thru an IR what type of speakers do I want to emulate, what typically goes in a DC30?
vigilante398
Authorized Vendor
Alright, I've been replacing my PCB offerings one at a time to switch everything over to the new setup with the tube daughterboard which I think makes the build more robust and gives a lot more room on the PCB. And I think it's finally time for Echo Foxtrot to go away. I still have a handful of PCBs on hand and if someone buys them I'll still ship them, but I'm working on the replacement for Echo Foxtrot right now and hope to have PCBs ordered by the end of the day.
jubal81
Well-known member
I absolutely love the EF86 Vox/Matchless hybrid amp I built. Sounds amazing on its own and takes pedals like a champ.
An alternative to the EF86 I've been eyeing is a 12AU7 wired as a cascode. I'm a devotee of Merlin's books and he's backed that option as sounding almost identical with none of the drawbacks of the EF86 (cost, microphonic, etc.).
An alternative to the EF86 I've been eyeing is a 12AU7 wired as a cascode. I'm a devotee of Merlin's books and he's backed that option as sounding almost identical with none of the drawbacks of the EF86 (cost, microphonic, etc.).
vigilante398
Authorized Vendor
Looks like an interesting idea, I've never tried it though. May be worth looking at. I've had good luck with JJ EF86 for low microphonics, but they are generally a bit more expensive than 12AU7.
vigilante398
Authorized Vendor
It's going to have the new tube mounting setup, but it's also going to be a different circuit. The current plan (which has already been designed and prototype PCBs have been ordered) is to do a preamp based on the EF86 channel of the Matchless DC30, my favorite channel of my favorite amp ever.
