ABY Splitter with isolated out

[Mat88]

Hello, anyone looked at the radial aby pedal circuit?
I did not found any schematic of aby pedal that has switches options like the radial.
I'm sure it is a simple circuit, i know there is quite a few online but most needs +9v and -9v for opamps which radial doesnt need, also many many broken links that are very old...
Why is no one making a layout or schem of this pedal? I mean it's very popular...
They use AEE19-3460, i opened mine, i need a few and i wanted to diy it to build 4-5 for my studio.
TY-141P seems a good alternative? better than the 42TM018?

[ElectricDruid]

Hi Matrix,

Do you mean this thing?:

https://www.radialeng.com/product/bigshot-aby/

(Providing the link so I didn't have to go looking for it would have been a nice touch)

You could also have explained that AEE19-3460 is a transformer. I know quite a lot of part numbers, but I'm not a Mouser catalogue.
The product page says that the pedal is entirely passive, so it shouldn't be too hard to work out. Can you post plenty of photos of the insides of yours, please? Both sides of the PCB if there is one (I'm guessing so for the switches). Then we might be able to work out the schematic. I had a look at the manual:

https://www.radialeng.com/wp-content/uploads/2022/07/BigShot-ABY-web-09-2021.pdf

After reading that, it's possible to have a pretty good guess what's in the box and what the switches are doing.

[FiveseveN]

Gut shot from their website: https://www.radialeng.com/wp-content/uploads/2018/04/BigShot-ABY-inside-768x677.jpg

[ElectricDruid]

Gut shot from their website: https://www.radialeng.com/wp-content/uploads/2018/04/BigShot-ABY-inside-768x677.jpg

Oooh, that's beautiful! So tidy!!

Alright, so there's no internal wiring at all to worry about, so all we need is a pic of the other side of the board. I don't suppose they supplied one of those too?!? 

[R.G.]

https://www.alliedcomponents.com/storage/transformers/pdfs/aee19-3460.pdf

Digi-Key sell them for ~ $10, but there is a $25 shipping fee attached to that.

https://www.digikey.com/en/products/detail/allied-components-international/AEE19-3460/13982242

They say "high frequency transformer" but then do not specify a frequency response or enough numbers to back-calculate it. Could be GREAT, or not so much. Probably fine.

Edcor sells similar stuff, and is generally great quality and frequency response.

The schemo for the Big Shot is here: http://guitar-fx-layouts.238.s1.nabble.com/ABY-w-phase-reversal-and-ground-lift-td38354.html


There are some limitations in using a purely passive 10k:10k transformer for isolation. Depending on the other internal details of the transformer wind, this might be OK, might not. The geofex.com versions went to active drive for the transformer because this makes it possible to use a small, cheap transformer without losing any bass, and to remove secondary loading effects that can affect treble.

In general, the smaller the transformer, the more bass-limited it will be. In addition, a passive transformer design makes the whole path susceptible to treble loss from loading reflected to the primary from the secondary. It will vary with whatever you plug into the  secondary.

I tested the Xicon transformer in the geofex design and found that driven passively, it was marginal with guitar (significant drop at 82Hz, low E) but was fine up to over 20kHz. The active drive got the bass rolloff down to the 60Hz region.

[ElectricDruid]

The schemo for the Big Shot is here: http://guitar-fx-layouts.238.s1.nabble.com/ABY-w-phase-reversal-and-ground-lift-td38354.html

Thanks, RG. That's pretty much what I was imagining. There *are* limitations with a completely passive design, even if there are advantages too (like it still works with no power...but if the amp's gone off, how useful *is* that exactly?!?)

Still, it would be a easy thing to reproduce - get the best transformer you can, since it's the only part in the whole thing that's not a direct metal contact. The trouble there is "best" is a slippery concept, with a lot of possible interpretations...

[taudio]

Hello, anyone looked at the radial aby pedal circuit?
I did not found any schematic of aby pedal that has switches options like the radial.
I'm sure it is a simple circuit, i know there is quite a few online but most needs +9v and -9v for opamps which radial doesnt need, also many many broken links that are very old...
Why is no one making a layout or schem of this pedal? I mean it's very popular...
They use AEE19-3460, i opened mine, i need a few and i wanted to diy it to build 4-5 for my studio.
TY-141P seems a good alternative? better than the 42TM018?

We used the TY-141P in the Super Transformer active DI box (published in the August 2024 issue of audioXpress) and found that like most inexpensive transformers, it also suffers from significant distortion at low frequencies. We used a mixed-feedback design approach which reduced low frequency distortion by around 30dB. You also get the improved frequency response that RG pointed out. Full performance data is provided in the audioXpress article.

The mixed feedback design approach is explained in Op Amp Applications -- see page 6.72

If you are open to an active ABY design, you could use mixed feedback by replacing the transformer output stages in the geofex ABY design with those shown in the Super Transformer. A copy of the Super Transformer schematic is attached -- also available here. Alternatively, you could use two Super Transformers with switching in front of them. We have PCB's available here if you'd like to build one yourself.

If you really want a passive DI, I recommend spending some money on a better transformer -- Hammond, Jensen and Edcor all offer good quality transformers that will perform *much* better than the TY-141P or AEE19-3460 in a passive design.

[Mat88]

I will reply to all the comments but for now i just wanted to post the inside pictures.
I will probe all resistors and caps to check where they connect.

[Mat88]

I checked some traces, just to realise it might be simpler to just build my own from available schematics and understanding how exactly it works, which i now understand better than when i started but i was still curious about the added resistors and caps in the radial.

Here's what i found  while testing with continuity meter.
I can't see well under the transformer though..
And take it as what it is, it might have errors in my testing...

[Mat88]

Hi Matrix,

Do you mean this thing?:

https://www.radialeng.com/product/bigshot-aby/

(Providing the link so I didn't have to go looking for it would have been a nice touch)

You could also have explained that AEE19-3460 is a transformer. I know quite a lot of part numbers, but I'm not a Mouser catalogue.
The product page says that the pedal is entirely passive, so it shouldn't be too hard to work out. Can you post plenty of photos of the insides of yours, please? Both sides of the PCB if there is one (I'm guessing so for the switches). Then we might be able to work out the schematic. I had a look at the manual:

https://www.radialeng.com/wp-content/uploads/2022/07/BigShot-ABY-web-09-2021.pdf

After reading that, it's possible to have a pretty good guess what's in the box and what the switches are doing.

Yes this one, sorry i thought there was only one aby pedal from radial...
This is my first post here and i never did this kind of thing with a branded pedal... I assumed people would check online if they really wanted to help figure it out looking at a partnumber or two isnt really a problem right? I appreciate the help. thanks

[Mat88]

https://www.alliedcomponents.com/storage/transformers/pdfs/aee19-3460.pdf

Digi-Key sell them for ~ $10, but there is a $25 shipping fee attached to that.

https://www.digikey.com/en/products/detail/allied-components-international/AEE19-3460/13982242

They say "high frequency transformer" but then do not specify a frequency response or enough numbers to back-calculate it. Could be GREAT, or not so much. Probably fine.

Edcor sells similar stuff, and is generally great quality and frequency response.

The schemo for the Big Shot is here: http://guitar-fx-layouts.238.s1.nabble.com/ABY-w-phase-reversal-and-ground-lift-td38354.html


There are some limitations in using a purely passive 10k:10k transformer for isolation. Depending on the other internal details of the transformer wind, this might be OK, might not. The geofex.com versions went to active drive for the transformer because this makes it possible to use a small, cheap transformer without losing any bass, and to remove secondary loading effects that can affect treble.

In general, the smaller the transformer, the more bass-limited it will be. In addition, a passive transformer design makes the whole path susceptible to treble loss from loading reflected to the primary from the secondary. It will vary with whatever you plug into the  secondary.

I tested the Xicon transformer in the geofex design and found that driven passively, it was marginal with guitar (significant drop at 82Hz, low E) but was fine up to over 20kHz. The active drive got the bass rolloff down to the 60Hz region.

Yeah i saw this thread but being not so used to pedal layouts that block diagram isnt the whole story compared to what is on the radial board, the resistors caps etc. The other layout Neil mcNasty posted there seem to have no output working if using only out B, thats normal?

I understand the limitations, but is the radial also limited like what you explain? Because i mean i never noticed it and it's just fine for me but i could build one passive and one active with the buffer and test both and have fun with either one depending on what i'm doing.

[Mat88]

Is TY-141P better than 42TM018 for this application?
I guess both would work almost the same if i make it active buffered?
If used in passive layout, which one i should get?
TY-141P seems to have a good bandwidth enough... I wanted to keep it cheap to build and not too big so expensive transformer are bigger as i understand it, plus shipping from another site, price goes high quick.

[Mat88]

We used the TY-141P in the Super Transformer active DI box (published in the August 2024 issue of audioXpress) and found that like most inexpensive transformers, it also suffers from significant distortion at low frequencies. We used a mixed-feedback design approach which reduced low frequency distortion by around 30dB. You also get the improved frequency response that RG pointed out. Full performance data is provided in the audioXpress article.

The mixed feedback design approach is explained in Op Amp Applications -- see page 6.72

If you are open to an active ABY design, you could use mixed feedback by replacing the transformer output stages in the geofex ABY design with those shown in the Super Transformer. A copy of the Super Transformer schematic is attached -- also available here. Alternatively, you could use two Super Transformers with switching in front of them. We have PCB's available here if you'd like to build one yourself.

If you really want a passive DI, I recommend spending some money on a better transformer -- Hammond, Jensen and Edcor all offer good quality transformers that will perform *much* better than the TY-141P or AEE19-3460 in a passive design.

Thanks, there's a lot to read. I'll definetely check it all out.
Where would i get better transformer from Hammond, Jensen and Edcor ?
I would hear a noticeable improvement with them? For guitar signal, i'll have to test again but why did i never notice any sound degradation with the radial aby?
Are they much bigger? How expensive?
Except the 10k:10k impedance, frequency range and 1:1 ratio what other spec is important here in this context?

[R.G.]

Still, it would be a easy thing to reproduce - get the best transformer you can, since it's the only part in the whole thing that's not a direct metal contact. The trouble there is "best" is a slippery concept, with a lot of possible interpretations...

I personally would lay the PCB out so that several different makers' 10K:10K transformers will fit in different sets of holes and still work.

Yes, "best" always requires defining how you are going to score the various features. Actually, so does "better". Manufacturers of consumer goods frequently think that their latest iteration of -- whatever -- is "better" because they changed the colors on the packing boxes. The words "best" and "better" in fact have court-litigated definitions for product advertising.

I may think that a transformer is "better" because it's cheaper, smaller, heavier, has wider frequency response or lower hum pickup, or ... whatever.

[taudio]

Thanks, there's a lot to read. I'll definetely check it all out.
Where would i get better transformer from Hammond, Jensen and Edcor ?
I would hear a noticeable improvement with them? For guitar signal, i'll have to test again but why did i never notice any sound degradation with the radial aby?
Are they much bigger? How expensive?
Except the 10k:10k impedance, frequency range and 1:1 ratio what other spec is important here in this context?

"Better" depends on what you want. Jensen offers very high performance transformers and they are priced accordingly. Hammond offers a range of products -- from "broadcast quality" to lower end. I'm not that familiar with Edcor, but I took a quick look and they seem to offer good performance at a reasonable price.

Prices range from ~$120 (Jensen JT-11p-1) to ~$23 (Edcor PCW10k/10k or Hammond 107T). Most are going to be a bit bigger than the transformer in the Radial box because they offer wider frequency response (and likely reduced distortion at low frequencies). In this context, there is a (very) rough correlation between size and low frequency performance.

It's difficult to say whether would hear a "significant improvement" because it depends on what you're doing -- the distortion is level and frequency dependent -- take a look at the JT-11p-1 datasheet for an example of this.

You've got the key specs with impedance (10k:10k), frequency response, and turns ratio (1:1). Higher end transformers will also provide data as per the JT-11p-1 datasheet: phase response, and distortion versus level and frequency.

If you're happy with the performance of the Radial box, cloning it using the schematic that RG pointed out is a good option. However, if you want higher performance, you'll need a better transformer or an active design.

Looking at the photos you posted, the Radial box needs a power supply (for the LEDs), so why not go for an active design since you're going to be powering the box anyways? The GEO-FEX design is a good one that has been proven over many years.

For a bit of extra effort, you can use the mixed-feedback "trick" we used in the Super Transformer to reduce distortion at low frequencies. A key point of our design was to see if we could get high end performance from a low cost transformer (the TY-141P) via a clever circuit trick -- the answer is a clear "Yes"

[Mat88]

Thanks, there's a lot to read. I'll definetely check it all out.
Where would i get better transformer from Hammond, Jensen and Edcor ?
I would hear a noticeable improvement with them? For guitar signal, i'll have to test again but why did i never notice any sound degradation with the radial aby?
Are they much bigger? How expensive?
Except the 10k:10k impedance, frequency range and 1:1 ratio what other spec is important here in this context?

"Better" depends on what you want. Jensen offers very high performance transformers and they are priced accordingly. Hammond offers a range of products -- from "broadcast quality" to lower end. I'm not that familiar with Edcor, but I took a quick look and they seem to offer good performance at a reasonable price.

Prices range from ~$120 (Jensen JT-11p-1) to ~$23 (Edcor PCW10k/10k or Hammond 107T). Most are going to be a bit bigger than the transformer in the Radial box because they offer wider frequency response (and likely reduced distortion at low frequencies). In this context, there is a (very) rough correlation between size and low frequency performance.

It's difficult to say whether would hear a "significant improvement" because it depends on what you're doing -- the distortion is level and frequency dependent -- take a look at the JT-11p-1 datasheet for an example of this.

You've got the key specs with impedance (10k:10k), frequency response, and turns ratio (1:1). Higher end transformers will also provide data as per the JT-11p-1 datasheet: phase response, and distortion versus level and frequency.

If you're happy with the performance of the Radial box, cloning it using the schematic that RG pointed out is a good option. However, if you want higher performance, you'll need a better transformer or an active design.

Looking at the photos you posted, the Radial box needs a power supply (for the LEDs), so why not go for an active design since you're going to be powering the box anyways? The GEO-FEX design is a good one that has been proven over many years.

For a bit of extra effort, you can use the mixed-feedback "trick" we used in the Super Transformer to reduce distortion at low frequencies. A key point of our design was to see if we could get high end performance from a low cost transformer (the TY-141P) via a clever circuit trick -- the answer is a clear "Yes"

I was hoping to stay under 20-25$ each transformer.

hammond 142A seems fair enough quality?  look at the freq range, it's small and not expensive, what you think?
I can't find the graph of the AEE19-3460 and TY-141P to compare though...
https://www.hammfg.com/files/parts/pdf/142A.pdf?v=1697661931
It also specs phase shift and thd noise, i guess 142A is "better" than the other 2?

I have no problem using active, this is the one you refer to?
http://www.geofex.com/FX_images/TransformerSplitter.pdf
The thing with this one is it needs bipolar power for the IC, how do i achieve that with common easy to find parts?
With this one?
https://www.mouser.ca/ProductDetail/Analog-Devices-Maxim-Integrated/MAX1044CPA%2b?qs=0Y9aZN%252BMVCXfHpZN39Twfg%3D%3D

I found this elsewhere, not sure if its good? see attached image, geofex site does not work so it's kinda hard to find all the info...



Yes i will try this option too with the mixed feedback trick, i wonder if they did it on the radial pedal too?

[Mat88]

Hm which one is the newest best updated version of the hum free circuit?
This one?




Or this one?

[R.G.]

Hm which one is the newest best updated version of the hum free circuit?

There's lots of caveats, asterisks and footnotes to go with that "best". To ask someone what "best" is means that you are trusting their definition of what matters.
Do you mean ...\
- cheapest?
- simplest to build/wire?
- smallest?
- easiest parts to source?
- heaviest/lightest/... etc?
- lowest bass frequency cutoff?
- highest treble cutoff?
- widest bass ---> treble range?
- simplest or least complex circuit?
This list just goes on. What characteristics matter to you?

The geofex designs were to show what can be done with a simple 1 IC circuit and a cheap, highly available transformer. I considered adding a charge pump inverter to them to make them work from a single 9V supply like the Super Transformer Active design, but that wasn't the objective at the time they were designed. If the design was for a product I intended to sell, I might have added the +9V to -9V converter; you still could, as the opamps don't really care where their -9V comes from.

I'm with taudio - better depends on what you want. And what your skills are, which will definitely limit what you can do, as will your funding.

[Mat88]

Hm which one is the newest best updated version of the hum free circuit?

There's lots of caveats, asterisks and footnotes to go with that "best". To ask someone what "best" is means that you are trusting their definition of what matters.
Do you mean ...\
- cheapest?
- simplest to build/wire?
- smallest?
- easiest parts to source?
- heaviest/lightest/... etc?
- lowest bass frequency cutoff?
- highest treble cutoff?
- widest bass ---> treble range?
- simplest or least complex circuit?
This list just goes on. What characteristics matter to you?

The geofex designs were to show what can be done with a simple 1 IC circuit and a cheap, highly available transformer. I considered adding a charge pump inverter to them to make them work from a single 9V supply like the Super Transformer Active design, but that wasn't the objective at the time they were designed. If the design was for a product I intended to sell, I might have added the +9V to -9V converter; you still could, as the opamps don't really care where their -9V comes from.

I'm with taudio - better depends on what you want. And what your skills are, which will definitely limit what you can do, as will your funding.

I understand what you mean, it's often about trade offs ... but i have absolutely no idea about when both circuits i linked are from, were they made at the same time?
I bet one is newer than the other?
I mean one says improved hum free, what was it solving to be improved?
What one offers that the other don't? The differences ?
If i go with active circuit for this aby pedal, i will definetely use a charge pump, i hate batteries lol

[Mat88]

I'm looking at charge pumps now.
I guess either one of theses 3 will work fine to power either of theses circuits.. 
LT1054IP
TC1044SCPA
MAX1044CPA (seems a bit tricky to avoid blowing it up because of limited current output? i saw a video from diy guitar pedal on youtube)