this tells you and us nothing.turning the volume control above 9:00 or 10:00 was getting uncomfortably loud;
We don't know what attenuation is being applied.
We don't know where in the clock max is, nor where min is.
this tells us where min and max are, but not the attenuation at your preferred setting.fully cw was 6:00 and fully ccw was about 7:30. So 12:00 was 12 steps down from full volume, and was actually less than half rotation.
your earlier post tells us nothing.I usually have my DCB1 volume knob at or slightly above 12:00
this tells you and us nothing.
We don't know what attenuation is being applied.
We don't know where in the clock max is, nor where min is.this tells us where min and max are, but not the attenuation at your preferred setting.your earlier post tells us nothing.
Gee, I thought I told you exactly what I wanted to tell you. I told you that in both cases I was using a "standard" log taper pot. I know that there are many "log tapers", but they tend to share some characteristics. Take a look at this PDF from Bourns, for example: http://www.bourns.com/pdfs/gapno_panel_controls_taper.pdf Most audio-taper pots are similar (Alps have a very similar document), and have about 90% voltage attenuation at 50% rotation.
Further, I told you that with the DCB1 I am able to use a larger part of the available rotation of the volume control, and I like that.
Since you seem top want some more details, I measured the resistance of both pots. I measured them in-circuit, but of course with power off. The readings will be slightly off because of other elements in the circuit, but still should give you a good idea. The Arcam Delta 290 integrated amplifier uses a motorized 10K "A" taper pot. There are "index" marks around the volume knob, so I measured at each of those marks, although there are no detents. The DCB1 uses a 20K 21-step attenuator. I measured one channel in each case. Here are the results (R is resistance from input to wiper in kilohms, the rest should be self-explanatory):
Code:
Arcam
R V ratio % att dB
ccw 9.9 0 100.0% -inf
9.87 0.003 99.7% -50.37
9.79 0.011 98.9% -39.08
9.72 0.018 98.2% -34.81
9.61 0.029 97.1% -30.66
9.53 0.037 96.3% -28.55
9.35 0.056 94.4% -25.11
9.07 0.084 91.6% -21.53
8.76 0.115 88.5% -18.77
50% rot 8.4 0.152 84.8% -16.39
8.11 0.181 81.9% -14.86
7.75 0.217 78.3% -13.26
7.34 0.259 74.1% -11.75
6.37 0.357 64.3% -8.96
5.24 0.471 52.9% -6.54
4.13 0.583 41.7% -4.69
2.68 0.729 27.1% -2.74
0.54 0.945 5.5% -0.49
cw 0.05 0.995 0.5% -0.04
Code:
DCB1
ccw 19.63 0.000 100.0% -inf
19.61 0.001 99.9% -59.84
19.57 0.003 99.7% -50.30
19.50 0.007 99.3% -43.58
19.40 0.012 98.8% -38.62
19.27 0.018 98.2% -34.73
19.12 0.026 97.4% -31.71
18.91 0.037 96.3% -28.71
18.64 0.050 95.0% -25.95
18.32 0.067 93.3% -23.51
50% rot 17.91 0.088 91.2% -21.15
17.40 0.114 88.6% -18.89
16.74 0.147 85.3% -16.64
15.92 0.189 81.1% -14.47
14.92 0.240 76.0% -12.40
13.62 0.306 69.4% -10.28
12.00 0.389 61.1% -8.21
10.00 0.491 50.9% -6.19
7.38 0.624 37.6% -4.10
4.13 0.790 21.0% -2.05
cw 0.00 1.000 0.0% 0.00
Do you feel any better informed?
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I use self-powered Linkwitz Pluto speakers, and I usually have my DCB1 volume knob at or slightly above 12:00 (or let's say between 10:00 and 2:00). I consider this a good match.
Are you confirming that you listen @ -16dB
Depends on who else is in the room, but yes, that would be the "loud" end of the range where I listen.
It does not matter. What does matter is the overall gain of the amplifier.Yes, so now since we know I used the Arcam with the volume control in the 8:00-11:00 range, it is left as an exercise for the reader to determine the voltage gain of the Arcam preamp stage
In the other case your amp would have a gain, let's assume it is +28dB
and assume you have an RF filter fitted as well that loses another 1dB.
The preferred vol pot setting you listen at is -16dB.
The gain from the Source to the Speakers is (+28 -1 -16) = +11dB
i.e. the Speaker voltage is ~3.6 times the Source voltage.
You can measure this with a test signal and a voltmeter.
You could also check the Source to Speaker voltage ratio of the Arcam at your preferred listening level.
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Sjøstrøm Buffer
Would it be ok to add this buffer after the Dcb 1 and on the same supply ?
http://sjostromaudio.com/pages/index.php/hifi-projects/126-qrv05-diamond-buffer#.U_N4csV_vnd
Would it be ok to add this buffer after the Dcb 1 and on the same supply ?
http://sjostromaudio.com/pages/index.php/hifi-projects/126-qrv05-diamond-buffer#.U_N4csV_vnd
will it be possible to accept unbalanced sources by shorting pins 1-3? Will it work?
Yes, as much as doing it in any XLR preamp.
the DCB1 has limited output current.Your buffer delivers to little power I think. I would like some more dynamic sound. I would use the DCb 1 before Volume control and Sjøstrøm after.
If you need/want more output current than what the DCB1 can provide then build a different Buffer that suits your needs.
The DCB1 has a vol pot followed by a Buffer (with it's own AC to DC PSU). It's all integrated on the PCB.
If you want a Buffer before the vol pot then the DCB1 is not what you need.
Sort out what your requirements are and then select suitable Buffers to fit that.
A DCB1 plus another higher current Buffer afterwards is nonsense.
Strange discussion using common words as power. What is needed, lower z out, more voltage swing or lower noice?
With power i mean more A. But more voltage sving would be nice to.
So a new design with higher voltage and more I max would be nice.
It not that I consider it bad. I just want more
With 7mA Id and 270R Rsource it can drive anything above 5K input impedance rail to rail with 3mA spare in full rise time ability. That is 20V pk-pk. 2VRMS digital source is 6V pk-pk.
Well thats nice Salas but it just do not sound like that.
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