Effectrode LA-1A tear-down and trace adventure

[sonolink]

Any progress on this project?
Any comoarisons with the real thing?

Cheers

[vigilante397]

Any progress on this project?
Any comoarisons with the real thing?

Cheers

Oh right, I posted the finished pictures in the pictures thread but never updated this thread (welcome to the forum by the way )

So I ended up dropping one of the 12AU7 to run two parallel triodes in the front end instead of four. This reduced the power draw and also allowed me to bring the size down to fit a 1590BB instead of a 1590X. I also dropped the boost section to save room on footswitches and just raised the overall output level. It doesn't sound 100% like an LA-1A, but it sounds at least 90% like an LA-1A. There are I think 5 of these out in the wild now, but no one has posted a formal review yet. You can hear some clips on my website, but I never recorded direct A/B demos against my LA-1A: https://www.sushiboxfx.com/deep-dish

[sonolink]

 
Wow!! Did you DIY that? Man, what a beauty!!

Hehehe I was interested in knowing about the progress of this project to consider building one but from what I see on those photos this is probably way over my head. I'm more a through-hole hand soldering guy if you know what I mean

Congratulations for the pedal. It looks awesome!!

One question please: the last schematic of the circuit+PSU section you posted on Nov. 22nd (https://i.imgur.com/OTTdIfE.jpg), is it error free?

Thanks for the pics and again, my sincere congratulations

[vigilante397]

Wow!! Did you DIY that? Man, what a beauty!!

Hehehe I was interested in knowing about the progress of this project to consider building one but from what I see on those photos this is probably way over my head. I'm more a through-hole hand soldering guy if you know what I mean

Congratulations for the pedal. It looks awesome!!

One question please: the last schematic of the circuit+PSU section you posted on Nov. 22nd (https://i.imgur.com/OTTdIfE.jpg), is it error free?

Thanks for the pics and again, my sincere congratulations

Thanks There has been debate about whether my stuff is still considered DIY with all the machines I use My soldering is done with paste and a stencil then into a reflow oven, enclosures are CNC milled, powdercoated and UV printed. So it's all still done in my house by me, but my hands are less involved than they used to be.

So that schematic is theoretically error free, it is completely accurate based on my trace of the LA-1A, but I was not able to get it to work the way I wanted it to, which may have been due to my power supply. A couple notes:

- For my builds I removed V2, R7, R8, R9, R10, R30, R31, C8, C9, C38 and C39. You can remove these without affecting the operation of the circuit, you just lose a little "fatness" on the first stage.
- Replacing R33 with a lower value resistor (or a jumper) brings the output level up if you're omitting the boost stage.
- R11, R12, and Q1 are only for the gain reduction indicator, they are not part of the original sidechain and can be left off.

SMD layouts are a lot easier for me than through-hole layouts, there are a lot more tricks you can get away with in my opinion. Best of luck to you if you're considering doing a build like this, I'd be happy to answer any questions

[sonolink]

Thanks There has been debate about whether my stuff is still considered DIY with all the machines I use My soldering is done with paste and a stencil then into a reflow oven, enclosures are CNC milled, powdercoated and UV printed. So it's all still done in my house by me, but my hands are less involved than they used to be.

If YOU do it and do it at home it's definitely DIY for me. I also use a CNC and a 50w laser now.
Many times I've been thinking about jumping over to SMD but to be honest I always end up cowardly slipping away from it

SMD layouts are a lot easier for me than through-hole layouts, there are a lot more tricks you can get away with in my opinion. Best of luck to you if you're considering doing a build like this, I'd be happy to answer any questions

Thanks a lot for your indications. I will definitely consider getting into this build shortly since a bassist friend of me has asked me to build him an LA2A When I learned he wanted it for playing on stage I began looking for a pedal version and bumped into this thread. I also found Moosapotamus' Fat'n'Pretty but I'm not sure it's really like an LA2A since it's tubeless.

What problem did you run into with the PSU in your design?

I can't stop looking at those pics. That is REALLY some serious good work!

Cheers
Sono

[vigilante397]

I mostly got into SMD because I do circuit design for my day job and everything is SMD there, so I started getting really comfortable with what I can do with it. I use 0805 passives which are what I consider to be the smallest you can hand solder without a microscope and without hating yourself, and I continued to hand solder them for a while, but I sell a lot more pedals now than I used to so I need to save time everywhere I can, and stencil + paste + reflow oven saves A LOT of time.

Anyway the main problem with the power supple was (I think) that I wasn't getting enough juice out of it for all three tubes and the rail was sagging. When I pulled one of the 12AU7 out the rail jumped back up to where it was supposed to be, and frankly I like the sound of it with two tubes. It still covers a lot of the same territory as LA-1A, but it can do some less-subtle compression with swelling as well.

And thanks again, I think it's the most complex design I've done (so far) and I'm pretty proud of it

[sonolink]

You should certainly be proud of that babe!!

Building is a hobby for me. My knowledge in electronics is pathetic...I wish I had more time to study designing but my building skills are not too bad so I just keep skipping...I build mostly tube amps and studio gear. I can read schematics and draw layouts and PCBs but I don't really understand most of the circuits (I began sort of understanding power supplies just recently). So I ended up into guitar pedals lately (a couple of years ago) because I love guitars, tubes and more and more often guitarists and bassists get more and more lazy and tired of carrying their gear around. So I got myself into tube preamps with DI outs and that sort of stuff in 1590BB and 1590XX format with the idea that you can go to the studio or to the gig just carrying your instrument and a 1590BB or XX.

I guess sooner or later I'll have to get into SMD soldering

Do you remember what is the aproximate juice needed for the circuit you traced?

Cheers
Sono

[vigilante397]

You should certainly be proud of that babe!!

Building is a hobby for me. My knowledge in electronics is pathetic...I wish I had more time to study designing but my building skills are not too bad so I just keep skipping...I build mostly tube amps and studio gear. I can read schematics and draw layouts and PCBs but I don't really understand most of the circuits (I began sort of understanding power supplies just recently). So I ended up into guitar pedals lately (a couple of years ago) because I love guitars, tubes and more and more often guitarists and bassists get more and more lazy and tired of carrying their gear around. So I got myself into tube preamps with DI outs and that sort of stuff in 1590BB and 1590XX format with the idea that you can go to the studio or to the gig just carrying your instrument and a 1590BB or XX.

I guess sooner or later I'll have to get into SMD soldering

Do you remember what is the aproximate juice needed for the circuit you traced?

Cheers
Sono

I never measured it, but I do still have the LA-1A I traced it from so I may try to do that, it would be interesting to see how much they're pulling.

Tube preamps with DI are the thing right now, I have my first prototype set to box up tonight. Most of my customers right now are bassists, so they want something that can compete with the Noble preamp but smaller and cheaper

[sonolink]

I never measured it, but I do still have the LA-1A I traced it from so I may try to do that, it would be interesting to see how much they're pulling.

That would be great indeed and I would be very grateful if you could provide that info.

Why not use 6v for the heaters? There's a nixie PSU transforming 9v into 190VDC+6VDC that I used once for a Showman preamp. I used a 9v/2A wall wart for it and it fed 2 tubes. Maybe it would do for this?

Cheers
Sono

[vigilante397]

Why not use 6v for the heaters? There's a nixie PSU transforming 9v into 190VDC+6VDC that I used once for a Showman preamp. I used a 9v/2A wall wart for it and it fed 2 tubes. Maybe it would do for this?

Why use 300mA at 6V when you can use 150mA at 12V? Running heaters in series instead of parallel saves a lot of juice. My whole build pulls less than 1A, and frankly you can still run the tube heaters in series at 9V and it works, so anything 9V or 12V rated for 800mA or more should do the trick.

[Ben N]

Submini version in 3, 2, 1....

[vigilante397]

Submini version in 3, 2, 1....

I obviously thought about it But I decided I'm actually going to start moving away from subminis. Now that I found a good form factor to fit a 12AX7 in a 1590B (or more comfortably in a 125B) all my new designs are full-size tubes. The subminis are neat, but they're power hungry, more prone to microphonics, and difficult for end users to work on, which is becoming more of a concern.

[sonolink]

Why use 300mA at 6V when you can use 150mA at 12V?

Well precisely, why do that? Because I have no idea about designing
This is the PSU I'm talking about:



If you have a better/optimized version and would like to share it, I would be very interested and grateful. I'm always eager to learn apart from building on the way

Cheers
Sono

[vigilante397]

Why use 300mA at 6V when you can use 150mA at 12V?

Well precisely, why do that? Because I have no idea about designing
This is the PSU I'm talking about:



If you have a better/optimized version and would like to share it, I would be very interested and grateful. I'm always eager to learn apart from building on the way

Cheers
Sono

So the high voltage section there with the NE555 is almost exactly the setup I use for high voltage. The 7806 will work, but it's not efficient so it uses more power and generates heat. It's better to run the tube with 12V across pins 4 and 5 instead of jumping 4 and 5 and putting 6V across them and pin 9.

[sonolink]

Mmmm ok, I follow you and your words make total sense...but how do you get the 12v? I mean, using the One Spot 9v/2A wall wart I use is kind of easy and straight forward if you know what I mean
Do you use a 12v PSU or a voltage pump or soemthing else probably more elegant?

Cheers
Sono

[vigilante397]

Honestly you can use a 9V supply the same way you would a 12V, the heaters are spec for 12V on the heater but my experience is that they work fine with 9V. So I don't use a regulator to step 9V to 12V, it's either a 9V power supply or a 12V power supply.

[jubal81]

What 12V power supplies are you using? I got the one from LoveMySwitches and was extremely noisy because - I think - the switching frequency clashed with the 555 SMPS. A 9V one-spot powers it without noise, but I'm wondering what to use at 12V.

[vigilante397]

So I should preface this by saying that I put a schottkey bridge rectifier in all of my pedals so they can run with center positive or center negative supplies.

The 12V supply I use is a Chanzon 12V 1.5A that I got on Amazon, it's fairly quiet and I like it. It's center positive though, so if you use it you'll need to either use a polarity switcher or some other way to put it in the right way.

[sonolink]

Honestly you can use a 9V supply the same way you would a 12V, the heaters are spec for 12V on the heater but my experience is that they work fine with 9V. So I don't use a regulator to step 9V to 12V, it's either a 9V power supply or a 12V power supply.

Wait a sec...are you saying that I can use a 9v/2A wall wart PSU to feed that circuit I posted, BUT with the heaters wired for 12v (in series) instead of 6v (in parallel) and everything will probably work and SOUND just fine?

Cheers
Sono

[vigilante397]

Honestly you can use a 9V supply the same way you would a 12V, the heaters are spec for 12V on the heater but my experience is that they work fine with 9V. So I don't use a regulator to step 9V to 12V, it's either a 9V power supply or a 12V power supply.

Wait a sec...are you saying that I can use a 9v/2A wall wart PSU to feed that circuit I posted, BUT with the heaters wired for 12v (in series) instead of 6v (in parallel) and everything will probably work and SOUND just fine?

Cheers
Sono

Yup