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Old 28th July 2011, 04:11 PM   #3081
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Hi Gents ,

can anyone suggest a volume control to use with this build ... Novice rears his ugly head again ...

cheers , Rich
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Old 28th July 2011, 04:58 PM   #3082
AndrewT is offline AndrewT  Scotland
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Does Pass suggest a 20k?
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Old 28th July 2011, 05:01 PM   #3083
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25 K ohm is what is suggested by NP ...
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Old 28th July 2011, 05:07 PM   #3084
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Hi Andrew ,

this is available to me from a fellow forum member .... http://www.rapidonline.com/netalogue/specs/66-0226.pdf

Now an in put selector ... looking for three inputs ... Pearl 2 , DAC and a spare

Just starting to collect parts .


Rich

Last edited by richluvsound; 28th July 2011 at 05:10 PM.
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Old 28th July 2011, 05:16 PM   #3085
AndrewT is offline AndrewT  Scotland
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I have no idea what your budget is, but if that seems good value for your money, then go for it.
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Old 28th July 2011, 05:27 PM   #3086
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I wasted a ton of cash on my amp build ... 20 quid seems sensible . I did find out that a lot of my problems were caused by working with far higher temp when soldering .

New digital station .. Start with this little project this time

I want good solid quality parts without getting boutique silly . I can always change parts later .

I would like to use a split rail supply ,but everything gets confusing in the thread . I'm on page 56 and the design just keeps changing . I wish there was a beginners area here on the forum . I'm sure folks get frustrated with me cluttering up their thought process with very basic questions .

Rich
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Old 28th July 2011, 09:53 PM   #3087
Thago is offline Thago  Belgium
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Quote:
Originally Posted by AndrewT View Post
A balanced impedance connection must have the impedances balanced (matched) both at the transmit end and at the receive end. The B1 input will be the receive end. All the components that determine it's input impedance MUST be matched to a an accuracy you have determined is adequate for your use. This includes the Capacitor loading.

The output of the B1 is the transmit end. The resistor on the output dominates the send impedance, you can probably get away with matching the output resistor only and use nominal +-5% components for all the others.
Okay, do I understand it right that the exact value of the C's is not the most important, as long as they are carefully matched?
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Old 28th July 2011, 10:18 PM   #3088
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by richluvsound View Post

Now an in put selector ... looking for three inputs ...


Rich
this Lorlin is real cheap http://docs-europe.electrocomponents...6b8007a1e8.pdf

Lucas Stabilty is probably a lot more solid, with longer life
cost more, but still cheaper than 'audiophile' parts

I doubt you can actually hear any difference
or maybe the cheap Lorlin actually 'sounds' better
as long a they function properly
but then, a nice feel gives confidence of good sound too

remember you need 'brake before make' (BBM) for a signal switch
and for building resistor attenuator it should be 'make before brake' (MBB)
I think it is
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Old 29th July 2011, 09:21 AM   #3089
AndrewT is offline AndrewT  Scotland
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Originally Posted by Thago View Post
Okay, do I understand it right that the exact value of the C's is not the most important, as long as they are carefully matched?
Yes, if 10uF lets all the audio through then whether it is 9.3uF or 10.9uF does not really matter.
But as far as the balanced impedance connection is concerned, the two halves (hot & cold) of the connection must have the same impedance, i.e. same resistance and same capacitance to a very tight tolerance. Aim for better than 0.1%

The two channels of a stereo connection do not need to match each other, 1% or 2% is probably inaudible.
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Old 29th July 2011, 09:28 AM   #3090
AndrewT is offline AndrewT  Scotland
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Originally Posted by tinitus View Post
remember you need 'brake before make' (BBM) for a signal switch
and for building resistor attenuator it should be 'make before brake' (MBB)
I think it is
Make before break is important to an attenuator switch. It prevents a loud click and with some systems could result in maximum signal going to the receiver for very loud noise.

I am not sure that break before make is correct for selector switching/muting.
The DCB1 has a break before make relay as the delay switch. While it is open the receiver sees an open circuit (near infinite impedance) on it's input and uses that as an aerial to pick up whatever it can.

Selector relays and selector switches that go open will do the same to any receiver.
Some receivers will oscillate if the input is momentarily left open.
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