B'ASS Current Amplifier

[PeterSt]

Arjan,

Aha ...
I mentioned "~ 50cm" because I actually don't care *and* I know that a bit too long is not comfortable and a bit too short doesn't really work out. Haha.

I know from my own situation how tough it is to have those very stiff cables guided like I want and I too had to make an estimate on the length required. This is all "custom work".
Whether it helps you I can't really tell, but you can have any length (assumed it is reasonable).

Btw, making those very short lengths is a total pain because the inner core of the cable shifts in the outer core when putting (or pulling) pressure on the inner core. Maybe not easy to explain, but the short lengths are quite undoable to make. But alas ...

Perter

[Stanray]

Hi Peter,

In my setup the Nos1a has balanced BNC outputs to the balanced power amps, so 2 BNC's/Blaxius's per channel.

How will the B'ASS look like (and cost) in my situation?

Regards,
Stanley

[Arjan]

Peter,
Is it possible for you to determine the right length of the short blaxius when positioned Nos1a and B'ass next to each other?

Else, where are the in- and outputs on the B'ass are positioned? With that knowledge I could figure out the needed length.

Arjan

[acg]

Do you think a switch and phono-in and perhaps a volume control could be incorporated?  After all it seems as though this new device is acting as a preamplifier.

You are probably right. But where you go wrong is where any small change which wasn't intended, right awy kills the sound. It is (or feels) similar to the attempt of having RCA next to BNC which I gave up after a month of trying different things. It just wouldn't work out, or say it always sounded worse as the one and only good set up : the genuine 75 Ohm.
So if I'd so this, then the first thing what happens is that I can't listen to it myself. Oh, I can, but then you're forcing me to listen to vinyl.

But quite easy do do it yourself ? This is all not even in the SMD domain. Just input cabling.

N.b.: The box size is a bit over-measured because I don't want the power supply to influence the amplifier boards plus I want the cabling guided around all what could influence for the worse. So there's really space left in there.

Thanks Peter.

Don't worry about the vinyl.  I am more concerned with other analogue inputs such as an FM tuner et cetera.  It would be nice to (still) not have a preamplifier but to be able to use your active buffer for more than one input.  So if I was listening to some music through my DAC and then wanted to tune into a live FM concert it could be done without changing cables and all that associated messing about.

I could sort out a remote volume control whether that be a high end passive attenuator or something with the Muse chip and then I would have the flexibility I need in that department.

Reading between the lines above it seems as though you don't think more than one input could work optimally for SQ...is this true?

Regards,

Anthony

[acg]

Oh, and I forgot to ask...is this buffer a dual mono configuration or do the two channels share the power supply?

[PeterSt]

Hi Frank,

You don't mention it specifically, but I assume if there is a headphone out then the B'ASS comes after the NOS1a in the music chain not before it?

Correct.

Perhaps add the B'ASS to your listed system?

Good idea; wasn't allowed up to yesterday, but now it os of course.

Have you measured the power output delivery of the headphone output jack?

No, but it will be like this :

Supposed the input voltage (= output voltage of D/A converter) = 2VRMS = 5.6Vp-p.
P = I x U tells that this is 2.8W. But :
With the knowledge that the current is 0.5A (max), R = U/I tells :
5.6 / 0.5 = 11.2 Ohm. Thus, this can drive 11.2 Ohm (when sufficiently cooled).
We don't need 11.2 Ohm, but say 32 (as the lowest). Now I = U/R tells :
5.6 / 32 = 0.175A. Notice that this is OK because it is 0.5A capable.
Next P = I x U again :
0.175A x 5.6 = 0.98W.

Maybe this was the long(est) way, but 0.98W is the answer, when 5.6Vp-p (2VRMS) is the input and the headphone has an input impedance of 32 Ohms.

For fun the power amplifier at the other end  :

Say this is 47000 Ohms input impedance. Repeat of the above :

U/R tells :
5.6 / 47000 = 0.000119A. Notice that this is OK because it is 0.5A capable.
Next P = I x U again :
0.000119A x 5.6 = 0.000667W.


As a bonus (for Matt) when we'd drive loudspeaker drivers of 4 Ohms :

U/R tells :
5.6 / 4 = 1.4A. Notice that this is NOT OK because it is 0.5A capable.
Next P = I x U again :
1.4 x 5.6 = 7.84W.

Mind the NOT OK;
This is also not OK because the voltage is 5.6 Only. So we need gain (provided by additional components I mentioned earlier on). The PSU can provide 34Vp-p. Now assumed the transformer will be sufficient large, then :
The board can provide 3.5A. Let's say that we need 14Vp-p, mind you, of continuous power ! then :

U/R tells :
14 / 4 = 3.5A. Notice that this is NOT OK because it is 3.5A capable.
Next P = I x U again :
3.5 x 14 = 49W.
This is per SE channel. Thus, would that be differential then this is doubled : 98W (which would be 34WRMS continuous power per channel.
And if the heatsinks are large enough, this all just works; this was all tested during the NOS2 project ...

Regards,
Peter (who hopefully did not make too many math mistakes)

[PeterSt]

Oh, and I forgot to ask...is this buffer a dual mono configuration or do the two channels share the power supply?

Anthony,

It is shared. But this is only because I planned it like that.
From origine it all does not matter, as this springs from the 8ch design and the whole configuration is as flexible as can be (read : the number of channels serviced by a PSU really does not matter, as long as it can take it).

Please keep in mind that I am not into "audio idiocy" and that a PSU which can supply 7A or whatever it exactly is, is not going to be bothered by two channels requireing 0.000x whatever Watts.

Btw, the plus and minus can be regarded double mono (especially if I'd use separate trafo's instead of two secundaries from one ... but I don't).

Peter

[PeterSt]

Don't worry about the vinyl.  I am more concerned with other analogue inputs such as an FM tuner et cetera.  It would be nice to (still) not have a preamplifier but to be able to use your active buffer for more than one input.  So if I was listening to some music through my DAC and then wanted to tune into a live FM concert it could be done without changing cables and all that associated messing about.

I could sort out a remote volume control whether that be a high end passive attenuator or something with the Muse chip and then I would have the flexibility I need in that department.

Reading between the lines above it seems as though you don't think more than one input could work optimally for SQ...is this true?

Anthony, not explicitly. You guys just come up with more than I planned for this. Anyway let me tell you in advance that I think the price is not super high, especially if you think about all the design efforts (and the now emerged flexibility). But this is exactly the culprit : step out of this line and design starts again.

Example about the volume : If you ask me I say "undoable". I mean, if it is not allowed to be detrimental to SQ, forget it.
However, the NOS2 design solved that, with weeks of design. Think voltage references and the output responding to that because of the design itself (which explicitly took that into account). This does not do that.
And on a side note and FYI : applying any volume in the differential domain is a challenge in itself, because there should be no deviation between the two differential channels at all (while L/R is easliy allowed to deviate 0.5dB (I say !)). So with differential any volume control is almost a no-go, unless we step back 10 years (of say Phasure) and don't know much about anything BUT that our sound is not the best of the world. Understand ?
This is also how I claim to have learned so much from the NOS2 project, never mind no NOS2 is there. I can tell right now within seconds all the things which will *not* work. But behind such seconds is weeks of thinking ...

All what is "switch" will be too high-Ohmic and therefore no good in the input. One thing I am not so very much experienced with : we are already at a reasonable (line) level. So it is not in advance of a DAC where nothing is allowed regarding switches and such. Anyway, what I would allow for almost sure is just two inputs in parallel. Maybe this is harmful, maybe it is already world-wide known that this is not allowed, but without examining it, I say it may be OK.
What is NOT OK is connecting two devices in parallel to the outputs, what many people do (like power amps + subs to the NOS1 RCA and XLR outputs which are live in parallel).

You know, I am afraid that we are "designing" ourselves more than really necessary, and that any 700 euro device as of now, becomes 1200 euros. Maybe that's OK, but ...

But anyway I now realize that I also have a digitally controlled volume ready on a PCB (f*ck, what did I not do the past 4 years ?!?). It is only that I never really worked with it (so I have the PCB and that is all -it also requires uC programming). But I recall that this too was actually a bit too difficult and it requires some sort of calibration (the differential problem, described above).

Hey, I am not against anything. But I had one purpose with it and this was just better sound from the NOS1(a). I think we now must be careful not to make it unnecessary expensive for some. But I listen ...

Regards,
Peter

PS:

But anyway I now realize that I also have a digitally controlled volume ready on a PCB

... which was for the DSD board I also have and never even bought one resistor for. So tempt me and that is in the same box too. Especially because that is voltage output and requires a buffer.
Anything else ?

[PeterSt]

Is it possible for you to determine the right length of the short blaxius when positioned Nos1a and B'ass next to each other?

Hi Arjan,

Of course, if you tell me what is at the left and what at the right side ... But not at this moment because :

Else, where are the in- and outputs on the B'ass are positioned? With that knowledge I could figure out the needed length.

I am not sure yet. Of course I have something working myself in a prototype (also wooden) box, but I must determine other things more definitive, such as where the power inlet will be (and this determines a lot). So while the size of the box has been determined, the backpanel layout is not yet.

Something else could be that with the NOS1a and the B'ASS next to each other, it really could be a challenge of where to put the cabling. Mine goes upwards from the NOS1a to the B'ASS on the shelf above it. And as you can imagine that just works. When going sideways it first has to go up (or down) anyway.
Think about this ...

Peter

[Gerard]

My plan was to put it on top of the NOS1a. No other way possible.

 

[PeterSt]

In my setup the Nos1a has balanced BNC outputs to the balanced power amps, so 2 BNC's/Blaxius's per channel.

How will the B'ASS look like (and cost) in my situation?

Hey Stanley,

Yes, you are an exception I did not think about. And aplogies, because you actually have the best connection of all of us !

This is what I added to the original post about it :

4.
With 2x BNC-In and 2x BNC-Out. Balanced Stereo B'ASS. Output Impedance 2x 75 Ohms.
Including Headphone output stereo jack (Single Ended). Output Impedance 2.9 Ohms.
920 euros.

The price follows from the difference between RCA and normal BNC (130 euros) with the notice that I grant this situation actually 1 pair of Blaxius for free (not completely true, but anyway think of 2 pair of Blaxius for now 130 euros).
Happy to do this for you (but no obligations from your side of course).

Best regards,
Peter

[doublelife]

Peter,

This sounds amazing..... I've just read the thread very quickly, and now I need to read it all again.

I will need #2. Actually I would like #2 but without the headphone out, price? How do we order - email?

Paul

[Scroobius]

Hi Peter - put me down for a #3 please

Thanks

Paul

[PeterSt]

I will need #2. Actually I would like #2 but without the headphone out, price? How do we order - email?

Dear Paul,

I just put you on the list and by the time we're ready you will receive an invoice. No worries.

The Headphone out just comes along with it. I mean, I didn't calculate one penny for it although the connector will cost a bit. But otherwise there will be a hole in the case ...

Thanks !
Peter

[doublelife]

Peter,

Oh well in that case I will have the headphone-out, no holes please! Just the tight-a*se in me trying to save a few $$....

Paul