Passive preamp buzzing?

[walpurgis]

I'm inclined to agree but I have read somewhere that the percentage of an RCA plug body that actually makes contact with the socket is about 1%. Which is concerning if true. I mean it is never going to make a huge difference, but I don't wonder that all these little things add up. I'm of the opinion that if something is sub-optimal but can be made optimal for little expense and effort, then it is worth making it optimal.

All plug/socket interfaces are a compromise, as no metal surface is truly even. For example, just run a high precision dial gauge across a carefully machined or ground steel plate and irregularities can be found.

[Marco]

I'm of the opinion that if something is sub-optimal but can be made optimal for little expense and effort, then it is worth making it optimal.

I'm both a perfectionist and 'completist', so if when I'm modding something, I've already gone to the trouble and expense of fitting the best internal components, then the external ones will simply be subjected to the same treatment, otherwise the 'What if?' demon would continue to haunt me!

Also, assessing the individual sonic effect (if any) of all these things, provides valuable learning experience, which for me is what hi-fi is all about, as you can't comment with authority on anything, unless you've actually tried it

Marco.

[Barry]

Sounds like 'an answer looking for a problem' Oliver. Decent RCA phono plugs are just fine. Some don't like them, but they work.

Even the metal they are made from is less critical than many suppose. If the conductor cross section and plug/socket contact area is adequate and clean, the plugs will perform just fine.

Yes - SMA connectors are made of brass gold-plated. As such they are not intended for repeated mates and de-mates, as the plating quickly wears through. Also at radio frequencies the skin depth is small (~ 3um at 1GHz) so virtually all of the current will flow through the gold. At udio frequencies the skin depth is much larger (~2.25mm at 1KHz), so now most of the current flows through brass. There is also a limit to the size of cable that can be fitted to them. (I think RG58CU is the largest diameter cable that can be readily used with them, though cables using specialised larger diameter cable (such s those using Gortex dielectric) are available from specialist RF cable manufacturers.

I see no advantage in using SMA connectors over RCA types. One would have to go to the trouble of replacing the chassis RCA sockets with SMAs on all your equipment. Best stick to good quality RCAs IMO.

[Joe]

My understanding is that XLR connectors are better than RCA for long cable runs, but that this advantage is limited for the 1m cables that most of us use (well, I do anyway). Lockable connectors avoid the danger of shorting caused by accidentally yanking out a cable, when moving kit for example. In any event, RCA has become the de facto standard for audio, even if it's (slightly) sub-optimal. (See Betamax vs VHS for comparison).

[Bigman80]

Blimey, I've only been away for a day and there's a shedload of posts!

Here is a suggestion Oliver, this will be of interest to many I would think.

To really compare the GP, and possibly add some drive, follow it directly with an active preamp.
I'll bring my KIN around and we can set it with the volume control at maximum so it's straight in to the active line stage.

What would that do, Alan or highlight? I have no idea about this sort of thing lol

Sent from my EVA-L09 using Tapatalk

[walpurgis]

What would that do, Alan or highlight? I have no idea about this sort of thing

Act as a buffer?

[Bigman80]

Act as a buffer?

What would a buffer do? Honestly I'm not thick lol. I've not been into hi-fi that long so this sort of stuff is all new

Sent from my EVA-L09 using Tapatalk

[Marco]

I see no advantage in using SMA connectors over RCA types. One would have to go to the trouble of replacing the chassis RCA sockets with SMAs on all your equipment. Best stick to good quality RCAs IMO.

Yet, Barry, you actively seek not to on your own equipment, and to my knowledge have a preference for using equipment fitted with connectors used in professional applications...?

Take SMA connectors out of the equation. What about the likes of Cannons or XLRs (leaving aside the balanced thing), or whatever your favourite connectors and sockets are?

IMO, and I'm sure I've heard you say it before, these offer a more robust and reliable connection than RCAs, which you're on record as saying you consider as inferior in comprison, in that respect.

*That* is the point I was making earlier to Oliver, which Jez came in and stamped on with his big size 12s, not anything to do with 'sonics'.....

Although, that aside, my suspicion is that for those reasons they *could* also improve SQ, due to (as I understand it) them offering a greater contact area, and which may result in maintaining superior signal integrity. That's the subjective bit!

Marco.

[Marco]

My understanding is that XLR connectors are better than RCA for long cable runs, but that this advantage is limited for the 1m cables that most of us use (well, I do anyway).

Indeed, Joe. But I'm talking *specifically* about the plugs and sockets, and how effectively they 'mate' together on equipment, when forming a connection. Nothing to do with the partnering cable. If you've ever used XLRs, in that respect, and compared them with RCAs, you'll be well aware that there appears to be no comparison.

And for me, knowing that in hi-fi how everything matters, even just a little bit, that's likely to impact *some* way on the sound. I'd certainly love to test it subjectively sometime!

RCA has become the de facto standard for audio, even if it's (slightly) sub-optimal. (See Betamax vs VHS for comparison).

Yes, and remember what happened there? VHS was rather more than "(slightly) sub-optimal"; it was grossly inferior.... Which ably proves that what's often claimed in audio as being the 'latest and greatest', and afterwards adopted universally, isn't always that!

I suspect that RCAs fall into that category.

Marco.

[Barry]

I'm inclined to agree but I have read somewhere that the percentage of an RCA plug body that actually makes contact with the socket is about 1%. Which is concerning if true. I mean it is never going to make a huge difference, but I don't wonder that all these little things add up. I'm of the opinion that if something is sub-optimal but can be made optimal for little expense and effort, then it is worth making it optimal.

In most electrical contacts the actual amount of contact area is about 10 - 15% of the available contact area. It is accepted good engineering practice when joining electric busbars that the overlap length is 6 -10x the thickness of the busbar.