Re-amp box Splitter

[audion]

Hello to all,

I would like to build a re-amp box with splitter to record 3 guitar amps simultaneously.
I search in the net to find a schematic about it without any success, i found only for passive reamp and with one output.
As I know the circuit must have a buffer in front and 3 transformers to make the impedance matching.

Does anyone have a schematic for a build like this?
Thank you in advance!

[antonis]

Hi & Welcome..

https://www.diystompboxes.com/smfforum/index.php?topic=114849.0

https://www.pinterest.ca/pin/106327241173649257/

In case of buffer existence, there isn't any need for impendance matching..

[audion]

Hi Antonis,

Thank you for your reply.
To split the balanced signal that will come from a console and to send it to 3 transformers you need buffers that will make the job.
Please check the attached photo of the Radial JD7.

I know the design that you send me, it's a passive but in my case I would like an active.

Thank  you Antonis.

[antonis]

To split the balanced signal that will come from a console

That information wasn't included in your initial post..  

So, what exactly is your issue..??
If it's the "active" naminig, buffers already have taken care for this..
(meaning, just copy 3 blocks of Radial JD7 diagram..)

[audion]

It was my mistake that I didn't mention active Re-amp - splitter, I am sorry.

As you can see on Radial diagram, they use a transformer after Balanced In and some buffers after.
Please do you have a schematic of what buffer should I build?
Can you guess what type of transformer is this after the Balanced In?

Thank you Antonis.

[antonis]

Please do you have a schematic of what buffer should I build?

My bad..
(didn't realize your initial query was about buffer design..)

What is your power supply availiable..??
(meaning from voltage and single/dual polarity viewpoint..)

[audion]

Thank you Antonis,

My power supply is dual, 24V and 48V.

To explain to you better the chain will be:

Balanced in from console out (Line signal XLR) --->Split signal ---> Buffers---> Transformers ---> Unbalanced Out ---> Guitar amp

[antonis]

By "dual" I meant +/- polarity (e.g. +15V, GND, -15V..)
(those ground lift switches make me think for +/- supply..)
So plz check it..

In the meantime, read about basic buffers here: http://www.muzique.com/lab/buffers.htm
In case of bipolar supply, we can easily handle it up..
(actually, it will be more plain than single supply circuits..)

[GGBB]

The main purpose of the transformer is not impedance matching - it's balanced to unbalanced conversion and ground isolation (although both can also be done without a transformer). The JD7 uses one transformer for balanced conversion and isolation of the balanced re-amp signal and device, and a bunch more for phase inversion and isolation of the outputs and devices/amps. Ground isolation avoids noise from ground loops, which can be a big problem when long cable runs connect multiple powered devices with different ground potentials. The buffers are used to handle impedance considerations just like buffers in pedal circuits.

For a home studio setup, you might not need the output transformers - all gear could be plugged in to the same AC in the room and not have problematic ground potential differences.

For the same reason, you might not need the input transformer, and your DAW might have an unbalanced output so you don't need balanced conversion either.

But you will need buffers, and those are simple. For ideas see http://www.muzique.com/lab/splitter.htm and http://www.runoffgroove.com/splitter-blend.html (input section).

If you need output isolation, they are passive, and you can find them commercially for probably a lot less money than you could build them. You're in luck because you need three outputs, so to isolate them all you only need two channels of isolation, and those are common e.g. https://www.amazon.com/PYLE-PRO-PHE400-Eliminator-2-Channel-Outputs/dp/B00BARTW42/ref=sr_1_19?crid=VOWDV186NRZK&dchild=1&keywords=hum+eliminator&qid=1593598982&sprefix=hum+elimina%2Caps%2C289&sr=8-19 (not an endorsement - never used it).

For DIY balanced conversion and isolation check out https://www.diyrecordingequipment.com/products/l2a (not an endorsement - never used it). There's a link on that page to the "open source" project details if you don't want to buy the kit.

[audion]

By "dual" I meant +/- polarity (e.g. +15V, GND, -15V..)
(those ground lift switches make me think for +/- supply..)
So plz check it..

In the meantime, read about basic buffers here: http://www.muzique.com/lab/buffers.htm
In case of bipolar supply, we can easily handle it up..
(actually, it will be more plain than single supply circuits..)

Antonis my power supply has two outputs, +24V-0, +48V-0.
It's not a bipolar power supply.

[audion]

The main purpose of the transformer is not impedance matching - it's balanced to unbalanced conversion and ground isolation (although both can also be done without a transformer). The JD7 uses one transformer for balanced conversion and isolation of the balanced re-amp signal and device, and a bunch more for phase inversion and isolation of the outputs and devices/amps. Ground isolation avoids noise from ground loops, which can be a big problem when long cable runs connect multiple powered devices with different ground potentials. The buffers are used to handle impedance considerations just like buffers in pedal circuits.

Thank you GGBB for the nice explaination.
This tool is for a studio setup with long cables (balanced) and the amps will be in a separate room, that's why I need the Active Re-amp.

As I understand, the first transformer makes the conversion balanced to unbalanced and please correct me if I am wrong, for this conversion I can use the Jensen JT-11P-1.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-11p-1.pdf

After that I will split the signal that I will send to buffers.

Thank you also for the links, I will check them.

[antonis]

ΟΚ then..
48V are too high for "ordinary" op-amps so you can proceed with 24V single supply, with 12V Vbias (reference voltage)..
(sorry Jack for violating your draws..)



The right one is for less noise (although the use of OPA2134 or NE5532 should exhibit superior "quietness"..)
and you can use 2 X TL072 (dual op-amps) with the 4^th amp used for Vref stabilizing..

[GGBB]

Thank you GGBB for the nice explaination.
This tool is for a studio setup with long cables (balanced) and the amps will be in a separate room, that's why I need the Active Re-amp.

As I understand, the first transformer makes the conversion balanced to unbalanced and please correct me if I am wrong, for this conversion I can use the Jensen JT-11P-1.
https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-11p-1.pdf

After that I will split the signal that I will send to buffers.

Thank you also for the links, I will check them.

That Jensen is 1:1. This would maintain the signal level of the input at the output which might be "+4dBu" "pro" level. At some point in your signal chain you'll need to pad that down because it would probably overload your amp or pedal "consumer" level inputs. It's more common to see a stepdown transformer (e.g. 4:1) used in these types of applications to provide the level padding at the start. The Jensen JT-10KB-D is meant for that (https://www.jensen-transformers.com/wp-content/uploads/2014/08/jt-10kb-d.pdf).

But there are much more affordable options such as Edcor (not an endorsement - never used them) for both 1:1 and 4:1 (https://www.edcorusa.com/wsm_series, https://www.edcorusa.com/pc_series).

[audion]

Thank you GGBB for your reply.
I saw that I cannot find Jensen in Europe, I will check EDCOR but do you know if I can use a Lundahl into the position of Jensen?

I found this one that you can use it a 4:1
https://www.lundahltransformers.com/wp-content/uploads/datasheets/7901_02.pdf

and this one for phase split
https://www.lundahltransformers.com/wp-content/uploads/datasheets/1588.pdf

If you found anyone in Lundahl website please you can inform me.
Thank you!

[audion]

ΟΚ then..
48V are too high for "ordinary" op-amps so you can proceed with 24V single supply, with 12V Vbias (reference voltage)..
(sorry Jack for violating your draws..)



The right one is for less noise (although the use of OPA2134 or NE5532 should exhibit superior "quietness"..)
and you can use 2 X TL072 (dual op-amps) with the 4^th amp used for Vref stabilizing..

Antonis thank you very much.
I will try the right one for less noise.
24V is very good.

Thank  you!

[GGBB]

Thank you GGBB for your reply.
I saw that I cannot find Jensen in Europe, I will check EDCOR but do you know if I can use a Lundahl into the position of Jensen?

I found this one that you can use it a 4:1
https://www.lundahltransformers.com/wp-content/uploads/datasheets/7901_02.pdf

and this one for phase split
https://www.lundahltransformers.com/wp-content/uploads/datasheets/1588.pdf

If you found anyone in Lundahl website please you can inform me.
Thank you!

They look like they will be fine (note that I am not an expert on transformers). But very expensive - I hope you can find Edcor in Europe - they are about 1/5th of the price. Maybe here? https://www.don-audio.com/navi.php?JTLSHOP=61546f044b4170ed50fc073104d5d3e1&k=9&hf=0&Sortierung=3&af=0.

[PRR]

> To split the balanced signal that will come from a console and to send it to 3 transformers you need buffers that will make the job.

No. A console output can drive hundreds of feet of cable and up to 80 guitar amp inputs. More if you recognize that a guitar amp needs MUCH less signal than a console can deliver.

I do NOT see a need for "active".

Three 10k:10k transformers seems a happy solution. In some markets, a "transistor radio" 10k:2k transformer is readily available, and will give a small drop of level (still plenty to beat-up the guitar amps).
https://www.amazon.com/EI-14-Audio-Transformer-pcs-Pack/dp/B07NPTBRZ9
https://www.mouser.com/ProductDetail/Triad-Magnetics/TY-142P?qs=Fg5d7evCuakf7g9SpG8XGQ%3D%3D
https://www.mouser.com/ProductDetail/Hammond-Manufacturing/145N?qs=ZbvfEmtlVQuSxbIXdPsyvg%3D%3D
https://www.mouser.com/ProductDetail/Xicon/42TM002-RC?qs=dY%252BBECfYuwVcZPIL%252B5HnFg%3D%3D
https://www.store.calrad.com/45-708

However I suspect that the amps do not all distort at the same input so will want different levels. Since we still have more than enough signal, a potentiometer for each amp will do what we need.

[audion]

Hello Paul,

thank you for your advice.
I fully understand what you mean but please can you inform me how can I split the one XLR console out to 3 transformers, without to have a signal quality loss?
For this situation it's not necessary to use a buffer after splitter?

Thank you Paul!

[audion]

They look like they will be fine (note that I am not an expert on transformers). But very expensive - I hope you can find Edcor in Europe - they are about 1/5th of the price. Maybe here? https://www.don-audio.com/navi.php?JTLSHOP=61546f044b4170ed50fc073104d5d3e1&k=9&hf=0&Sortierung=3&af=0.

Thank you GGBB.
Yes, they are expensive, I suppose that they are boutique style. I wil check also Edcor on the their website.

[PRR]

If the load impedance is much higher than the source impedance, multiple loads can be driven without degradation.