Required attenuation when connecting the Transporter XLR direct to an Amplifier

[Triplefun]

I currently connect my transporter to the unbalanced input of my
Audiolab 8200mb mono blocks using the unbalanced RCA connectors. I need
to be careful on setting the volume and not go TOO loud.

If I were to use the better quality XLR connectors I believe I will need
an in line attenuator (or pad).
The Transporter outputs 3vrms with an output impedance of 100Ohms.
The 8200MB max input sensitivity is 1.63Vrms with an input impedance of
20KOhms.

According to the wiki article
See
http://wiki.slimdevices.com/index.php/Connecting_directly_to_a_power_amplifier


Please confirm that I require a 5db XLR line attenuator
(=20*log(1.63/3.00) = -5.3db).

And does anyone know where I can get such a device ???


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[Mnyb]

Its actually hard to do passsive atenuators with such low atenuation .
Not that they will sound wrong but getting a matched pair !

You probably have o go with -10dB or nothing . I used rothwell
atenuators when i had analog stuff i think they offer xlr too



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sub.
Bedroom/Office: Boom
Kitchen: Touch + powered Fostex PM0.4
Misc use: Radio (with battery)
iPad1 with iPengHD & SqueezePad
(in storage SB3, reciever ,controller )
server HP proliant micro server N36L with ClearOS Linux

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[Gandhi]

+1 for Rothwell. They are very well built. The only downsides are their
length and that they come in an annoyingly high-end looking box. :-)

I used to use the -10dB XLR version with my Transporter, when
technically I should have used -14dB. I never noticed anything
detrimental with that. But now I have a digital solution instead, for
other reasons.

http://www.rothwellaudioproducts.co.uk/html/attenuators.html



Best Regards,
Gandhi

not often enough well recorded and mastered cds *|* dbpoweramp with
accuraterip *|* flac *|* fanless asrock z77e-itx intel i5-3570t *|*
ubuntu 12.04.1 lts 32-bit *|* lms 7.8.0 *|* brutefirdrc 3.0 *|*
transporter (balanced out) *|* thule ia252b *|* audio physic scorpio *|*
no fancy cables. *+* also some booms. *+* harmony 525s for them all,
including waking the server from s3.
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[Julf]

It seems I require a 5db XLR line attenuator (=20*log(1.63/3.00) =
-5.3db).
This seems rather low and is it really required?

The value itself is correct, as the attenuation you need is not very
much (and so little that I wouldn't bother with it) *if* you want to be
able to get full volume out of your system. That is a big if. If you
find that you normally listen at much lower volumes, you might want to
go with more attenuation.

The amps of my active speakers are teorethically capable of 1200W of
output power, but they are gain limited to only produce 200W or so at
full volume. I don't need louder than that, and it would probably blow
my speakers if I went full power.



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[Mnyb]

Post by Julf
The value itself is correct, as the attenuation you need is not very
much (and so little that I wouldn't bother with it) *if* you want to be
able to get full volume out of your system. That is a big if. If you
find that you normally listen at much lower volumes, you might want to
go with more attenuation.
The amps of my active speakers are teorethically capable of 1200W of
output power, but they are gain limited to only produce 200W or so at
full volume. I don't need louder than that, and it would probably blow
my speakers if I went full power.

Yeah that why i suggested -10dB .

It buys you some protection if dont listen at ear splitting levels .

It would work fine without it to , but ipk3 based squeezeboxes (sb3
transporter etc ) has a very rare bug when they sometimes emit noise at
full volume , you get it every 5 years or soo :) , fix is a xilink reset
.



--------------------------------------------------------------------
Main hifi: Touch + CIA PS +MeridianG68J MeridianHD621 MeridianG98DH 2 x
MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3
sub.
Bedroom/Office: Boom
Kitchen: Touch + powered Fostex PM0.4
Misc use: Radio (with battery)
iPad1 with iPengHD & SqueezePad
(in storage SB3, reciever ,controller )
server HP proliant micro server N36L with ClearOS Linux

http://people.xiph.org/~xiphmont/demo/neil-young.html
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[Julf]

Post by Mnyb
It would work fine without it to , but ipk3 based squeezeboxes (sb3
transporter etc ) has a very rare bug when they sometimes emit noise at
full volume , you get it every 5 years or soo :) , fix is a xilink reset
.

Ah, yes, good point.



"To try to judge the real from the false will always be hard. In this
fast-growing art of 'high fidelity' the quackery will bear a solid gilt
edge that will fool many people" - Paul W Klipsch, 1953
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[cliveb]

Rather than trying to guess/calculate the required attenuation, it's
trivial to actually measure it:

1. Hook TP XLR outputs direct to power amp inputs.
2. SET INITIAL TP VOLUME TO ZERO!!!
3. Start playing something that you like to listen to loud (eg. Led
Zeppelin/Metallica/etc).
4. Gradually turn TP volume up until it's as loud as you'll ever want to
go.
5. Read attenuation from TP's display.

If you are concerned about paying silly money for commercial
attenuators, you can add it into the existing XLR plugs on your
interconnects for pennies (or build removable attenuators for a few
dollars). See
http://wiki.slimdevices.com/index.php/DIYPassiveAttenuation



Transporter -> ATC SCM100A
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[darrenyeats]

I base my experience on attenuators of the DAC1 which degrade the sound
IMO, especially the 30db pad which is just egregious (Benchmark have
removed the 30db pad option for the DAC2 ... grist to my mill!)

So ... now I don't like putting any attenuators between the output of
the source and the input of the active speaker/power amp that affect
impedance. It bothers me. Think active versus passive crossover - do
what you need to do to the signal before the source drives the load, it
isn't necessary to do it between source and load.

I've heard the arguments about audibility (or lack thereof) but here's
the thing - it's just not -necessary- to change impedences with the
right gear.

For example, in the DAC1 there are the calibration trimmers, located
before the output of the DAC, these don't affect output impedance; ATC
actives have a input sensitivity trim +/-6db (1-4VRMS I believe),
unmarked on the amp pack but referred to in the manual, using these
doesn't affect input impedance; the new Young DSP DAC has an stepped
analogue attenuator on-chip before the output stage; I believe at least
some Weiss DACs can alter the reference voltage to the DAC chip to
change gain. All of these provide analogue attenuation but they don't
change the source/load impedance at all.

I do agree, though, that excessive digital attenuation is bad. If you're
permanently restricted to low volume settings, you are effectively
losing physical SNR in your source and you can hear that in some cases.
It might be that output/input attenuators could improve matters if
that's the case.

To me, the cleanest and best way to do it is how I described, but then I
acknowledge I'm paranoid. I'm not saying you can't achieve transparent
results otherwise. I have OCD and it's the way I choose to do it.



Check it, add to it! http://www.dr.loudness-war.info/

http://www.amazon.co.uk/gp/richpub/listmania/byauthor/A3H57URKQB8AQO/ref=cm_pdp_content_listmania/203-7606506-5721503.

SB Touch
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[sbb]

you could use a product like that:
http://www.thomann.de/gb/samson_sconvert.htm

this pro converter is supposed to work (and sound) quite well


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