RCA to XLR

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Black Stuart

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Joined 2005
#1
I would like a definitive answer to what I think is a simple question.

All my gear is RCA out and I'm thinking of buying a Topping LA90 D. I know I can buy an RCA to XLR adaptor but there are tales of dire warning if I use such an adaptor into the Topping as it is a balanced amp - true or false.
 
#2
If the Topping do have a true symmetrical input stage, there would be no problem to connect asymmetrical outputs to its input, providing a correctly wired cable adapter (XLR hot to hot pin of the RCA, XLR cold and ground to ground of the RCA).

But if the Topping is a bridge design throughout input to output, the situation is more delicate. In that case, it would be preferable to use a transformer input adapter. Such transformer would also be perfectly fine ahead of a symmetrical input stage if it is of good quality. In doubt of the exact topology of this particular Topping, I would advise to get a transformer adapter.

Best would be to contact Topping to ask directly the question.
 
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#3
 

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#4
Black Stuart said:
I would like a definitive answer to what I think is a simple question.
Click to expand...
The question is quite simple, its answer is not. IMO

While at least a couple of authoritative magazines state about using special adapter cables when you have only single-ended sources, I wouldn't do it.

https://www.theabsolutesound.com/articles/topping-la90-power-amplifier/

https://soundnews.net/amplifiers/power-amps/topping-la90-review-block-rockin-beats/

My view is that using adapters is a fallback, and it would be better not to think that it is not.

You will only get to not express the full potential of both your amplifier and then of your system.

If you can then make a further effort (or plan to do it) and also buy a source with balanced outputs, since you can do it even without a preamp having L90 Discrete amplifier or (better, integrated amp) a volume control.

Just sayin'...
 
#5
I've used the $3 Ebay RCA-XLR adapters from a disco mixer (RIAA input mm cartridge) to QSC302 power amp. Fine under 2 m in length. Over 2 m, specifically 4 m, the RCA coax cable picked up sports talk radio from a local AM station, also police and CB radio when they transmitted in the < 100 mhz band. Full differential twisted pair cables are good to 33 m as used between mixers in the audience and power amps on stage. By reputation, I've never played a show for an audience that big and my mixer was always on stage with me. The CX302 is differential only to the first op amp, the internals are single ended.
The sources of full differential output RIAA input mixers are the same stores that sell unicorns. All the TRS output mixers I've owned had fake differential ouputs, ie the shield and the opposite wire of the twisted pair were both grounded at the source jack. The jack was TRS but the drive was only the tip. The disco mixer has RCA jack out.
 
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#6
The definitive answer is....it's not a problem at all. Interfacing an unbalanced source to a balanced destination is as simple as it gets.
A standard RCA/XLR cable/adaptor will work just fine.
You'll have 6db less gain, but that shouldn't be a problem in almost all cases.

Dave.
 
#7
Davey said:
The definitive answer is....it's not a problem at all.
Click to expand...
For me too. 😉

My willing is that I do not want adapters on the (analogue) signal path, so I've all XLR connections/devices and also this is not a problem at all for me.

Just to specify that I was talking about SQ, not about the electrical feasibility because obviously if there are adapters out there is just because you can use them, don't you?

However, just as everyone knows the XLR connections have some advantages over single-ended ones, but I won’t list them because they are also known by the stones.

Are XLR connections not a real advantage in home systems, but only in professional ones?

Here everyone has their own beliefs and preferences, and I’ve already said mine. 🙂

Furthermore in my view there is no reason to buy a fully balanced amp in order to use it in an all-single-ended system.

Just my opinions.
 
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#8
The difference being, I don't base my comments on beliefs or preferences. 🙂
All other things being equal, adaptors (in this context) don't have any inherent issue regards sound quality.

BTW, very few amplifiers are fully balanced. Most, that have a balanced input interface, are just single-ended topology inside.

Dave.
 
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#9
Thank you for your appreciated reply.

Frankly, while not questioning at all what you say I still think that the matter is a bit more complex than that and that it is just the XLR connectiions that sounds very good.

https://www.audioaffair.co.uk/blog/xlr-vs-rca-interconnects-is-there-a-difference/

Anyway I just found this old thread, maybe interesting for the OP.

https://www.diyaudio.com/community/...er-causes-gross-amounts-of-distortion.275388/

However, if the OP wants just to do it I suggest him to look at the amp user's manual since AFAIK Topping specifies the XLR sockets pinout for all its devices.
 
#10
That DIYaudio thread outlines an issue with XLR/RCA conversion.....not RCA/XLR conversion. (Two completely different interfacing configs.)
And, as you'll note, I commented in that thread regarding that particular issue.

I suggest to read up before commenting further.

Dave.
 
#11
Davey said:
I commented in that thread regarding that particular issue.
Click to expand...
I can’t find the post you’re talking about, could you point it out?
Using Google Translate about specified technical details then the results are unclear sometimes.

What I noticed was that there were many different opinions, some about the correct grounding and so in those intricated cases I choose the safe way (that's, with no adapter) and most of all with no (not even hypothetical) grounding problems.

Only a personal choice, of course.
 
#13
First of all be calm please because nobody here is forcing you to post anything.

Please note that I cannot find anything on the Internet of what you are talking about, so I have to believe in your words at least until you kindly provide me other references.

Furthermore using the verb "understand" is not appropriate at all: you understand that, right???
 
#15
Indianajo/Davey/mdaudio thanks for the input. I thought that was the answer but wanted confirmation - thought is not reality. When I was using valve/tube gear I came upon the Tung Sol 6F8G preamp tubes (bloody marvellous) and used them in place of 6SN7 but had to use adapters. Even using adapters they outperformed everything else by a margin.

It's interesting that two of you mention the 6db drop. That so many manufacturers 'proudly' announce that their gear uses an Alps Blue, which IMO is a piece of crap unless you shunt it which I have done in the past using the wonderfully transparent Vishay Z foils. Doing that means a drop of 6db which was not a problem with the Heybrook Sextets mk 1Vs.
 
#18
Thanks Davey and others. As an update it seems the Topping LA90D develops problems after a little while, in fact this applies to quite a lot of their products. Those problems may all be heat related or not. Why cram everything into a small space and trying to hide so called secret circuits inside a black box is complete bllckx, since all any competitor has to do is buy a unit and remove the box. I noted that Topping has used very cheap power resistors hemmed in on all sides with no way to dissipate the heat generated except into surrounding components.

Whether I take a chance on this unit or not the advice about connecting my unbalanced equipment to balanced gear has been very informative. I find that the Chris Daly Stereo Coffee makes for an excellent preamp/volume control that I wouldn't want to give up. Maybe I will contact him to see if he has thought about designing a balanced unit.
 
#19
I've had nothing but good luck with Topping products. (But, YMMV.)
Regarding LDR volume controls...... Objectively speaking they have numerous problems and are out-performed by a variety of passive or active volume control solutions. (But, YMMV on that too.)

Regardless, all of that is irrelevant to your original query. Which has been answered satisfactorily, I think. 🙂

Have fun.

Dave.
 
#20
Black Stuart said:
Whether I take a chance on this unit or not the advice about connecting my unbalanced equipment to balanced gear has been very informative.
Click to expand...
I guess that if you just want to get a preamp you’ll have your reasons for doing it (so it would be useless to suggest alternative configurations, with no preamp at all).

I appreciate the fact you're finally planning to get a preamp to match the power amp, so if the preamp you currently like doesn’t have the balanced outputs maybe remaining in Topping could be a good idea.

Topping Pre90 could be a good choice in my opinion, I've it and I’m very satisfied with it, the most evident characteristic when listening is its extreme transparency IMHO.

https://www.stereophile.com/content/topping-pre90-line-preamplifier

It has been compared to preamps costing 30 times its cost.

Furthermore it would also respect the overall aesthetic. 😉

Just sayin'...
 
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