Passive preamp buzzing?

[Bigman80]

I don't think that Stereophile article explains what a buffer is very well at all.

A buffer is a device with a very high input impedance and low output impedance. There is one in one form or another at the output of virtually all pre amps, phono stages, CD players, DACS etc etc. It has no voltage gain but lots of power gain ie it doesn't amplify the signal but it does make it much more powerful. They are also called Voltage Followers as the output follows the input in voltage. A silly analogy, imagine Volts were speed... it's still doing 10MPH but before it was a toy sail boat doing 10MPH and which would be stopped or slowed by the slightest friction... after the buffer it's still doing 10MPH because the voltage hasn't been amplified... but now it could drag a tree at 10MPH.

Suppose we have a source with a high output impedance like 10K. If we were to try and drive a 10K passive it would form a potential divider with the output impedance of the source and therefore the output of the source would be halved by the presence of the passive even when set to full volume!

I is important to note that just because a buffer has a very low output impedance doesn't mean it can actually drive very low impedance loads! It implies this yes but without the current to back it up we would get lots of distortion. It can be designed to give all the current one could want of course and in fact the output stage of a SS power amp is almost always a buffer! Usually it's just designed to have more than enough for the intended use though.

Very good Jez. I definitely understand now. Why use valves then?

Sent from my EVA-L09 using Tapatalk

[Arkless Electronics]

Very good Jez. I definitely understand now. Why use valves then?

Sent from my EVA-L09 using Tapatalk

Purely to placate plonkers who think valves are automatically better and to gain more sales from exploiting this assumption. It's quite prevalent... think of all the CD players and DAC's which advertise "valve buffered". Transistors are vastly better as buffers but as 99.99% of buffers have 100% negative feedback they are intrinsically very linear (low distortion) by nature and even a valve one will commonly give <0.01% distortion plus bandwidth of DC to a MHz or more. In many ways the greatest figure of merit for a device is its transconductance. The higher the transconductance the lower the output impedance when used as a buffer. Transistors (BJT's) are orders of magnitude better than valves in transconductance.

[Bigman80]

Ok, so go valves then

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[Marco]

Jez, I've been very patient, but that patience has now run out...

Understand, that ignoring me is NOT an option, so do not make any further posts to the forum until you address my earlier question on this thread.

Ta!

Marco.

[Arkless Electronics]

Jez, I've been very patient, but that patience has now run out...

Understand, that ignoring me is NOT an option, so do not make any further posts to the forum until you address my earlier question on this thread.

Ta!

Marco.

You're taking the piss now Marco. You can't force people to enter debates! I don't wish to discuss connectors with you as no matter what I say, based on decades of electronic engineering experience and knowledge, you will say something like "I believe I can hear the difference between a BNC and phono plug and I don't care what it says in your Johnnies book of physics" or something to that effect.

You have on many occasions admitted having very little knowledge of electronics. In spite of this you believe you can argue electronics with a professional in the field by shutting down any discussion with the old "I believe I can hear it and I trust my ears" ploy. Incredibly, you've even on several occasions questioned the validity of the laws of physics if they go against your argument!!

In any "debate" with you the options are basically:

1/ Let Marco win.
2/ Give Marco some get out so he appears at least partially correct.
3/ Leave the debate. This last one appears no longer an option....
4/ One is so certain of ones facts that one would stake one's life on it so decide to not back down, no matter what, as a matter of principle.... then expect to be told to "STFU or get a holiday/be banned for life"

I believe you would in fact enter a debate with Professor Stephen Hawkings on the subjects of black holes or quantum entanglement and still never concede that he's proved you wrong on any single aspect of the subject

Once you had started with something like "I believe phono plugs are sub optimal and BNC's sound better", there is, as I am only too aware, nothing that I or anyone else could say that would result in you changing that to "now its been explained I can see that phonos are perfectly adequate for audio and there is indeed nothing to be gained by moving to BNC's"

Sometimes I get sick of the game and don't want to play.... I hope you find that a satisfactory explanation.

[karma67]

You're taking the piss now Marco. You can't force people to enter debates!

if im totally honest i thought that was a bit rich as well!

[Marco]

You're taking the piss now Marco. You can't force people to enter debates!

*I'M* taking the piss???

Who was the one who came in and said I was wrong? So, YOU were the one instigating a debate. I wasn't forcing you to do anything, other than explain to me why I was wrong!!

Then when repeatedly pressed to explain why, you just ignored me......!

*THAT* is what actually happened, not what you've 'imagined' instead, and if you scroll back and read the posts concerned, you'll see that for yourself. Furthermore, I'm not attempting to argue electronics with you. That's only in your head!

If you had actually read what I wrote properly in the first place (rather than jumping in with both feet, with your usual crassly absolutist statements), then you'd have noticed that I wasn't talking about 'sonics'; I was talking about the physical properties of each plug and how they've been engineered, in terms of offering the most secure and reliable connection.

Therefore, you've COMPLETELY MISUNDERSTOOD what I wrote, and I would like you to acknowledge that.

You need to understand that if you're going to tell me I'm wrong, and I press you to explain why, then you either do so, or don't bother telling me I'm wrong. It's that simple. You can't provoke a reaction from me, then run off when you get one!

Because I simply will not tolerate being rudely ignored. I have no problem whatsoever with being wrong, but if someone tells me that, then I insist on them explaining precisely why, not running off and refusing to play anymore, because they now regret what they've started!!

The rest of your 'rant' makes a complete mockery of the truth, so isn't even worth acknowledging, although the sheer hypocrisy [and comedy] of you stating that *I'm* the one who won't accept he's ever wrong, certainly won't have been lost on those reading who know full well what you're like!

Marco.

[Marco]

if im totally honest i thought that was a bit rich as well!

Yes, that's because you've also misunderstood what's happened. I suggest that you read what I've just posted, for the facts of the matter.

Marco.

[karma67]

so do not make any further posts to the forum until you address my earlier question on this thread.

Ta!

Marco.

my comment was referring to this,im not sure how i could misunderstand it?

[Marco]

Because I won't be rudely ignored like that. Therefore, when I ask someone what I consider is an important question, especially when it involves them telling me I'm supposedly wrong, I expect them to have the courtesy to reply and explain.

Normally, I wouldn't be so insistent, but Jez seems to be under the misapprehension that he can come onto threads, make absolutist statements like he did, and there will be no repercussions. I'm afraid he's in cloud-cuckoo land if he does!

Marco.