Unbalanced to Balanced Converter

[Starion156]

I have an ARC SP11 mk2 pre and need to hook it up to a pair of ARC Ref 210s. Pre has unbalanced RCA output and the power has balanced xlr input. Ideally I would upgrade the pre but that am stuck with the SP11 for now. ARC says the 210 will not sound good if I just use a cable or adaptor as it needs a true balanced input to work properly. Quoting a significant reduction in power and increase in distortion.

They say this can be solved by using a transformer based unbalanced to balanced converter or isolation unit to generate the balanced signal. The one they recommended is a PI-2RX from Jensen Transformers but they are quite expensive and only available from the US.

I found a UK based company RCH Audio Engineering who do one with similar specs which works out at about half the cost of the Jenson solution after you factor shipping and import duty/tax. It uses a custom wound transformer to RCH's own specifications. Anyone have any experience with these sorts of converter or RCH?

[The Black Adder]

Hi.

Get yourself an Alice Matchpak. Brilliant little things. I use one myself.

Sent from my 9001X using Tapatalk

[Barry]

Hello Mike,

Are you referring to this: https://www.etsy.com/uk/listing/884976376/twin-chan-line-iso-rch-twin-chan-line?ref=shop_home_active_5&frs=1 ? On paper it has a good specification: I would be interested to know the name of transformer manufacturer who supply RCH.

You can use it between the unbalanced output of your preamp and the balanced input of your power amplifier. You will need a pair of unbalanced cables, terminated with RCA phono connectors at one end and XLR connectors at the other end. Since this will be used with the RCH transformer, I would ask RCH to make up some suitable cables. Their prices seem quite reasonable.

[Puffin]

I have 4 U/B to Bal converters, 2 I have made myself using kits (op-amp based), One which has transformers (on sale in Pro Audio places) and one I got from an Audiojumble that looks identical to the Alice Matchpak but under a different brand. If you can solder then an op-amp based converter is fine....at least to my ears and around £20.

[Macca]

I'd try the interconnects first before looking at an expensive solution. I use XLR to RCA sometimes there's no noticeable issue, although I appreciate you are wanting to go RCA to XLR.

Even so only cost you a tenner to find out, could save you a fair wedge.

[Starion156]

Hello Mike,

Are you referring to this: https://www.etsy.com/uk/listing/884976376/twin-chan-line-iso-rch-twin-chan-line?ref=shop_home_active_5&frs=1 ? On paper it has a good specification: I would be interested to know the name of transformer manufacturer who supply RCH.

You can use it between the unbalanced output of your preamp and the balanced input of your power amplifier. You will need a pair of unbalanced cables, terminated with RCA phono connectors at one end and XLR connectors at the other end. Since this will be used with the RCH transformer, I would ask RCH to make up some suitable cables. Their prices seem quite reasonable.

Yes Barry I am. It does look good on paper not sure which manufacturer did the winding all I have been able to get form RCH so far is that they are their own design and custom wound to their own specification. How it performs in reality is another matter although I am temped at the price if it does not matter too much as long as the spec are correct.

I know Jensen based units are well regarded but its double the cost by the time you factor shipping and import duty and I can have the RCH in a few days.

[Barry]

Hi.

Get yourself an Alice Matchpak. Brilliant little things. I use one myself.

Sent from my 9001X using Tapatalk

https://www.alice.co.uk/product/alice-matchpak/

These are active solid-state devices which may use Lundahl transformers. They have a good specification. New, they are £250, but there are several available used for about a fifth of that price. At least there is no ambiguity with the interconects.

I suspect they are made for Alice by the same company who made EMO devices. I have an EMO MC/MM RIAA phonostage which looks of similar construction, is very well made and sounds good.

[The Black Adder]

https://www.alice.co.uk/product/alice-matchpak/

These are active solid-state devices which may use Lundahl transformers. They have a good specification. New, they are £250, but there are several available used for about a fifth of that price. At least there is no ambiguity with the interconects.

I suspect they are made for Alice by the same company who made EMO devices. I have an EMO MC/MM RIAA phonostage which looks of similar construction, is very well made and sounds good.Hi Barry.

I've got to know Paul, the owner of Alice and he's a brilliant chap and still producing and servicing kit.

Sent from my 9001X using Tapatalk

[Starion156]

I'd try the interconnects first before looking at an expensive solution. I use XLR to RCA sometimes there's no noticeable issue, although I appreciate you are wanting to go RCA to XLR.

Even so only cost you a tenner to find out, could save you a fair wedge.

I have some x cinema amps which have xlr inputs which I just us an adaptor which I got from Maplin to connect my RCA cables from my AV receiver and they seem to work fine with no issues. But looking at the circuit it is expecting a split signal already I think so not sure that works

[Barry]

I'd try the interconnects first before looking at an expensive solution. I use XLR to RCA sometimes there's no noticeable issue, although I appreciate you are wanting to go RCA to XLR.

Even so only cost you a tenner to find out, could save you a fair wedge.

When using adaptors, or adaptor leads, one side of the balanced connector is shorted out. If the output is balanced, then one half of the output is shorted, which depending on details of the circuit involved, may or may not be a problem. If the input is balanced, then the adaptor will short out one half of the input, which will reduce the sensitivity by 6dB, but ought not cause a problem; however Audio Research think otherwise for their designs.

[JohnJo]

Might be worth contacting Jez Arkless, I’m sure he could make you something up.

He’s advertising transformers here, just need put in a box with sockets or hardwired with cable.

https://pinkfishmedia.net/forum/threads/neutrik-ntl-1-balancing-transformers_line-level.252447/

[Barry]

Seeing the above post, reminded me of the Neutrik range of unbalanced to balanced transformers, like this: https://www.bax-shop.co.uk/di-box/neutrik-na2m-d0b-tx-miniature-transformer, or
https://www.dv247.com/en_GB/GBP/Neutrik-NA2F-D2B-TX-Miniatur-Transformer-Balancing-Adapter/art-ACC0006754-000?campaign=GShopping/GB&ProgramUUID=5G_AqJarZwoAAAFl0FZyjI8V&gclid=EAIaIQobChMItru2w77G8AIVAe_tCh1IYg0kEAQYFyAB EgIjv_D_BwE

A neat and inexpensive solution.

[Starion156]

Thanks for all the suggestions but I may have found a simpler solution having come across a post in a different forum which noted that the SP15 is similar to an SP11 in out put arrangement but ARC added balanced output which was derived from the direct and invert RCA output which the SP11 also has. So some custom leads which takes the hot from the direct RCA and the cold form the invert RCA should give me the 2 signals for the balanced output and I presumably can take the ground from any of the RCAs as they are all linked,

was going to post the schematic as way of illustration but cant seem to figure out how to do it and you don't seem to be able to past from cipboard.

Mike

[Blackdog]

That will work just fine. Just be wary of the position of the direct/invert switch.

[hifinutt]

Contact ovlov, he knows all about these I believe

[hifinutt]

I recall when I had ref 5 and rca only monoblocks. I got an esteemed cable maker to make a xlr to rca but it was no good . Had 2 attempts and just got hum

[AJSki2fly]

Sorry to jump i on this thread but it is something I have been wondering about, my amp has a balanced input, my Phonostage has RCA unbalance output. Would there be any benefit(sonically) in purchasing an Alice MatchPak and using it between the phonostage and amplifier?

[Barry]

Sorry to jump i on this thread but it is something I have been wondering about, my amp has a balanced input, my Phonostage has RCA unbalance output. Would there be any benefit(sonically) in purchasing an Alice MatchPak and using it between the phonostage and amplifier?

Does your amp have both an un-balanced (RCA) and a balanced (XLR) input? If so I doubt if adding an extra active stage (the Alice MatchPak) to convert the un-balanced output of your phonostage to a balanced output would make much of a difference in SQ (apart from adding 6dB).

[Barry]

Thanks for all the suggestions but I may have found a simpler solution having come across a post in a different forum which noted that the SP15 is similar to an SP11 in out put arrangement but ARC added balanced output which was derived from the direct and invert RCA output which the SP11 also has. So some custom leads which takes the hot from the direct RCA and the cold form the invert RCA should give me the 2 signals for the balanced output and I presumably can take the ground from any of the RCAs as they are all linked,

was going to post the schematic as way of illustration but cant seem to figure out how to do it and you don't seem to be able to past from cipboard.

Mike

Yes that will work fine. I believe some Chord electronics have a similar choice of inverting and non-inverting output RCAs.

[Starion156]

https://imgur.com/nKqlJQ0

https://imgur.com/nKqlJQ0


This is the schematic I was trying to upload earlier assuming it works this time round :scratch:https://imgur.com/nKqlJQ0

[Barry]

https://i.imgur.com/nKqlJQ0.jpeg

[AJSki2fly]

Yes that will work fine. I believe some Chord electronics have a similar choice of inverting and non-inverting output RCAs.

Thanks Barry, that answers it for me, if I want a better SQ(possibly) then it's purchase a phono stage with at least as good SQ as mine currently which also has balance outputs.

[Starion156]

I have a quick question about using the direct and invert output. ARC seem to think it would work but I noticed when responding to them that the SP15 schematic does not show any ground connection to the RCA unbalanced output. I always thought that RCAs needed a referenced ground so I assume there must be one. At first I thought it was so the ground on the balanced output was floating but if that was the case how would the RCA output work? Link to the schematic snap shots I took in the previous post.

[Starion156]

Hi Barry how did you get the image to show like that?

[Barry]

Hi Barry how did you get the image to show like that?

I clicked on the link you provided to get the image. I then 'right clicked' on the image and then clicked on "copy image address".

Then in a new post I 'right clicked' "post" and then bracketed the url with and .