Trying to eliminate noise totally

[Flecko]

I wonder if amp gain it important.

Yes it is. In general most of the noise you hear comes from the source and not the amp itself. The noise of the source is amplified by the amp in relation to the gain value.
That is why the list from mani...

1. Soul (15wpc DC-coupled valve SE)
2. Berning (5wpc DC-coupled valve SE)
3. Sauermann monos (40wpc class A PP)
4. Sanders (~500wpc class AB)
5. BD-Design monos (~100wpc gainclones - currently with input caps)

...could be misleading because the gain of the amps is not known. So you do not know how much the noise from source is amplified and hence you cannot say anything about the general quality of the amps. I do not know how much the noise of the amp itself playes a role with 115db speaker but from what I have experienced with normal speakers it can be totally neglegted.

[manisandher]

In general most of the noise you hear comes from the source and not the amp itself.

This may well be the case in most systems, but not with mine. I have two passive vol. controls - one RCA the other XLR. I can put them between the NOS1 and the various amps and the noise through the horns doesn't change at all with the control set to 0 vs. max. Remember, the noise out of the NOS1 is in the single-digit µV range.

Mani.

[manisandher]

Because the first amp (like the Soul) acts like a pre-amp for the second (the BD30 in your case). And the pre-amp determines the sound ...
(largely)

Sure, any 'preamp' is going to matter. But I always thought that the control the power-amp has over the driver is a larger factor.

Mani.

[manisandher]

What you also can do (or maybe should do) is get yourself a radioshack SPL meter, hold it at 1 meter or so exactly between the top and bottom horn, create a 285Hz test signal, play that and let someone else slowly turn the bass volume. When the output is the highest the XOver should be at its best.
This, assumed that the XOver midpoint for the Orphean horn is 285 Hz indeed, which I don't know. But most probably so.

When you found the highest output, do the same for 400Hz and 110Hz but now hold the SPL meter in front of the respective horns. First of all the level of both should be the same as were you ended with the volume balance. If it is not, than or the XOver just can't be made well at all because the both slopes are not equal and you are in bad luck.
Still you can attempt now to make the levels equal for the both frequencies from the respective horns, and after this look at the 285Hz again (if it is that at all) in the middle of both horns like before. Now you have the levels right (and mangling those for the better means subjective ears) but the XOver will be wrong. To what degree (haha) will be shown by the SPL meter. Don't be shocked when you see 10dB or more less output.

When you can't make any sense out of it at all, switch the plus/minus from the bass section (not sure whether that is easy to do) and start all over. Better now ? then leave it at that.

Notice that you can create a sort of best of worse by lowering (not highering) the bass volume, which may let rise the 285Hz level. Don't let it rise more than the level from the Orphean. So, now envision that you are creating an upwards going graduate level from bass to mid. Not the best, but also no hole in the Xover.

All right, from now on you will never forget how important this is, because you will see the results yourself.

Thanks Peter. I was actually thinking of getting a calibrated mic (Earthworks, or something) and using the RME software to capture some 20-20 sweeps. But I'll look into your approach too. Thanks again.

Mani.

[Flecko]

I have two passive vol. controls - one RCA the other XLR. I can put them between the NOS1 and the various amps and the noise through the horns doesn't change at all with the control set to 0 vs. max. Remember, the noise out of the NOS1 is in the single-digit µV range.

If feared you will tell this, so I used the word "general" before my statement That is an impressive performance and interesting to know it is possible.

[manisandher]

A quick update on the Tube Distinctions Soul 15 amp. Anthony Matthews got back to me. He checked the amp out and according to him, everything is working as normal. He suggested, and I agreed, that the Soul probably isn't the best match for my 115dB speakers. It just isn't quiet enough. He has given me a full refund.

It's a shame because it had a really nice quality to its sound. But if this was down to noise, then I'd rather not have it. In any event, the BD-Design gainclones are dead quiet (well, one channel at least) and are sounding seriously nice with the Swings. I'm going to have a crack at replacing the one noisy trannie this weekend. I'll report back on whether this affects the (slight) noise coming from the horn.

Mani.

[PeterSt]

Everybody who hold on will finally get there ...

But don't forget to listen to music !

Peter

[Flecko]

I just made a comparison between the noise of my AudioNET Amp1 V2 and my Linnenberg Amp 2S. If the volume poti is turned down, with the AudioNET amp I still hear noise from the speakers, if I have my ear in about 20 cm away from it. In the same configuration the Linnenberg is totally silent. This is the first time I realised there can be such a difference of amplifier noise. My 90db/w speakers are quite new to me and I always used speakers with low sensitivity so I would correct my statement. If the speakers have a sensitivity about 80db/w, amp noise can be neglected but from 90db/w up, definitely not.

Greetings

[PeterSt]

Hi there Adrian,

I hope it doesn't come too much as a surprise, but you should always listen to the noise at full gain. And I'm afraid you will have other thoughts about it all then.

This is not about whether noise can be tuned down by means of attenuation because the signal/noise relation will stay the same. It also is not about the noise not being able to hear so sound will be good. It is about the noise not allowed to destroy the signal. So set all to full gain, listen to the noise you peceive then, and envision how that noise mangles with the signal at any level.

And not to forget please : Were it for the audibility of noise, I perform the gag with 115dB sensitivity.

Hope this helps (better SQ, maybe not your mood ),
Peter

[Flecko]

I hope it doesn't come too much as a surprise, but you should always listen to the noise at full gain.

No it is not a surprise. This experiment should show me if I  can hear the noise of my amplifier.
At full gain I hear the noise of my DAC. I guess this cannot be reduced without a new design?

It is about the noise not allowed to destroy the signal.

Do you mean in the digital domain or how is the analog signal destroyed independently from SNR?

Were it for the audibility of noise, I perform the gag with 115dB sensitivity.

That is impressive. Is see my approach as the first step to what you have already achieved. I like the simplicity of the concept of low gain amp, volume poti and not to high efficiency speakers. I am glad to be informed by all of you, so amplifier noise is on my list now too.

(better SQ, maybe not your mood Happy)

Well, lets say I have nothing against better sound quality. At the moment there are so many things I can try (the noise problem beeing one of them). It is a lot of fun!

Greetings
Adrian

[manisandher]

Just a quick update and probably a final wrap-up of this thread...

You know, sometimes you only know how much something means to you once you've been without it for a while. Well last week I decided to try all the amps I had lying around to see which to stick with until my Orelino speakers arrive. And there's absolutely no question about it, the Sauermann monos are the amps. I blame the bloody bass controls on the back of the Swing speakers for creating a bunch of '"red herrings" for me. I've got Nick and Paul (Scroobius) coming over next weekend, and although there won't be time to swap amps around (and I don't really have the inclination to either), I hope they agree that the Sauermann/Swing combo provides a pretty nice sound.

Mani.