Looking for a small bit of gain
 

Sigh, I'll have to talk nice to some sighted people with soldering irons
then won't I? Not quite figured out how they make up 22 bits for such a
devce.
Still.


Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Woody" wrote in message
...

"Graeme Wall" wrote in message
...
On 04/07/2017 20:27, Woody wrote:
If you don't want the faff of getting the bits and building it then
N47FL at £6.99 from Maplin will do the job. Uses a NE5532 amp chip so
should be very low noise. Supply is 3-25V so any old PSU you have
lying around....



"Fun to solder." Not an expression I would use :-)

--
Graeme Wall
This account not read.



I would be grateful if contributors would make sure they attribute
comments to their sources. The quote above is exactly what I wrote and I
said nothing about 'fun to solder.'

Mind you if you have been taught and know how to solder properly it is
easy and can be 'fun.'


--
Woody

harrogate3 at ntlworld dot com

Looking for a small bit of gain
 

On 05/07/2017 07:22, Woody wrote:
"Graeme Wall" wrote in message
...
On 04/07/2017 20:27, Woody wrote:
If you don't want the faff of getting the bits and building it then
N47FL at £6.99 from Maplin will do the job. Uses a NE5532 amp chip
so
should be very low noise. Supply is 3-25V so any old PSU you have
lying around....



"Fun to solder." Not an expression I would use :-)

--
Graeme Wall
This account not read.



I would be grateful if contributors would make sure they attribute
comments to their sources. The quote above is exactly what I wrote
and I said nothing about 'fun to solder.'

That's what it said on the page linked to.


Mind you if you have been taught and know how to solder properly it is
easy and can be 'fun.'



I have been taught and know how to but it is still just a chore.

--
Graeme Wall
This account not read.

Looking for a small bit of gain
 

In article ,
Brian Gaff wrote:
Sigh, I'll have to talk nice to some sighted people with soldering irons
then won't I? Not quite figured out how they make up 22 bits for such a
devce.
Still.

If you want one built, Brian, I'll happily do it for you.

--
*Oh, what a tangled website we weave when first we practice *

Dave Plowman London SW
To e-mail, change noise into sound.

Looking for a small bit of gain
 

On Wed, 05 Jul 2017 08:48:36 +0100, Bob Latham wrote:

In article ,
Don Pearce wrote:
On Tue, 4 Jul 2017 19:23:34 +0100, "Brian Gaff"
wrote:

a single transistor stage with, say an emitter follower would suffice
though these days the over designers would probably use an Ic.
Brian

I'm confused again. When I went to school an emitter follower had no
voltage gain, it had current gain for want of a better expression.

Under-designers, you mean. With an IC you don't have to do any design -
just set two resistors to give you the gain you want.

And that is exactly how I would do this - it's by far the best way.

Yes.

Use non inverting config for lowest noise and then if I recall correctly
gain = 1 + (R-feedback / R-ground). No problems as you do not require a
gain of less than 1.

And, as it's being fed from the presumed Hi-Z DIN output designed to act
as a constant current source to feed Lo-Z DIN inputs, a simple Hi-Z input
unity gain buffer amp may be all that's required to feed a mid-Z phono
input with enough signal voltage.

The only benefits I can see with the DIN standard of constant current
sources feeding low impedance inputs is the automatic muting of
interference to unused inputs and the ability to join several sources,
each with their own volume control, to a single input to provide crude
but effective audio mixing (which makes the phrase "Sound mixer with DIN
output" a little oxymoronic to say the least - perhaps such a mixer is
simply a bunch of inputs going to simple volume controls with their
outputs all wired directly to the one output socket pin?).

--
Johnny B Good

Looking for a small bit of gain
 

On Wed, 05 Jul 2017 20:31:26 +1000, Trevor Wilson wrote:

On 5/07/2017 4:23 AM, Brian Gaff wrote:
Humph, well i thought it was me.
a single transistor stage with, say an emitter follower would suffice
though these days the over designers would probably use an Ic.
Brian


**And just to nit-pick: With a single transistor, operating as emitter
follower, you have a Voltage gain of less than 1. Just sayin'. I think
you mean 'common emitter'.

Brian has a point, assuming he's aware of the difference between the DIN
system and the phono plug based system, namely DIN's use of Hi-Z sources
driving Lo-Z sinks versus the use of Lo-Z voltage sources driving Hi-Z
phono inputs.


An OP amp is very, very easy, cheap and simple to implement. Distortion
is almost non-existent too.

The less than unity gain of an emitter follower is typically 95 to 98
percent of the input voltage, depending on the emitter load resistance
and the beta gain of the transistor used. Even with a gain of only 0.90,
interposing such an amp between a 100K DIN output and a 10K phono input
will provide a 20dB boost in signal level (even when both are 50K,
there'll still be a good 5dB advantage).

Using an op-amp circuit with non inverting Hi-Z input unity gain will
only add a dB or so boost at most to the classic emitter follower
amplifier solution so there's not a lot to choose between them other than
the fact that adding a simple variable resistor to the op=amp circuit
provides variable gain from unity upwards (say a 6 or 12dB boosting range
of adjustment).

A single PP3 (or, optionally-but not essential, two PP3s in the case of
the op-amp solution) should be able to provide dozens, if not hundreds of
hours of fun between changes of battery with such a self contained
boosting amplifier module.

If a more permanent battery-less solution is desired, I'd say the best
option would be to fit it inside the mixer box and provide the additional
phono socket(s) alongside of the existing DIN socket, rather than use a
seperate 9 to 12 volt noise free wallwart psu.

--
Johnny B Good

Looking for a small bit of gain
 

In article , Woody
scribeth thus

"Don Pearce" wrote in message
...
On Tue, 4 Jul 2017 20:27:14 +0100, "Woody"
wrote:

If you don't want the faff of getting the bits and building it then
N47FL at £6.99 from Maplin will do the job. Uses a NE5532 amp chip
so
should be very low noise. Supply is 3-25V so any old PSU you have
lying around....

That is exactly what brian is looking for


Was it Brian that was looking for it? I thought it was Duncan or Dave.

Brian might have a problem with it as it is in kit form!




They do one with flying leads on it, still require soldering mind...

--
Tony Sayer

Looking for a small bit of gain
 

In article , Dave Plowman (News)
scribeth thus
In article ,
Don Pearce wrote:
On Wed, 05 Jul 2017 10:11:34 +0100, Jim Lesurf
wrote:

In article , Don Pearce
wrote:
On Tue, 4 Jul 2017 19:23:34 +0100, "Brian Gaff"
wrote:

a single transistor stage with, say an emitter follower would suffice
though these days the over designers would probably use an Ic. Brian

Under-designers, you mean. With an IC you don't have to do any design -
just set two resistors to give you the gain you want.

And that is exactly how I would do this - it's by far the best way.

If it were me I'd probably buy one of the cheap kits I used for
http://www.audiomisc.co.uk/HFN/HeadDAC2/HeadDAC2.html

I don't know if the board is laid out for gain, but your headphone amp
shows a unity-gain circuit only. I can't imagine they failed to make
provision for gain, though.

Something always worries me about using a 5 volt single supply for line
level audio - assuming it is used neat. In the old days, 24v was the sort
of norm for pro stuff. Admittedly line level is higher with that. But when
ICs came along was +/-15v or more.


Remember reading a criticism of the Quad 33 pre-amp citing its 12v as
being too low.


Someone does a modified power supply for that now!...


--
Tony Sayer

Looking for a small bit of gain
 

I'd not want to dismantle the mixer, it might just kill it off, its rather
elderly but functional nonetheless. I like what I'm used to as modern stuff
if not just software is often not tactile enough for me.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Johnny B Good" wrote in message
...
On Wed, 05 Jul 2017 20:31:26 +1000, Trevor Wilson wrote:

On 5/07/2017 4:23 AM, Brian Gaff wrote:
Humph, well i thought it was me.
a single transistor stage with, say an emitter follower would suffice
though these days the over designers would probably use an Ic.
Brian


**And just to nit-pick: With a single transistor, operating as emitter
follower, you have a Voltage gain of less than 1. Just sayin'. I think
you mean 'common emitter'.

Brian has a point, assuming he's aware of the difference between the DIN
system and the phono plug based system, namely DIN's use of Hi-Z sources
driving Lo-Z sinks versus the use of Lo-Z voltage sources driving Hi-Z
phono inputs.


An OP amp is very, very easy, cheap and simple to implement. Distortion
is almost non-existent too.

The less than unity gain of an emitter follower is typically 95 to 98
percent of the input voltage, depending on the emitter load resistance
and the beta gain of the transistor used. Even with a gain of only 0.90,
interposing such an amp between a 100K DIN output and a 10K phono input
will provide a 20dB boost in signal level (even when both are 50K,
there'll still be a good 5dB advantage).

Using an op-amp circuit with non inverting Hi-Z input unity gain will
only add a dB or so boost at most to the classic emitter follower
amplifier solution so there's not a lot to choose between them other than
the fact that adding a simple variable resistor to the op=amp circuit
provides variable gain from unity upwards (say a 6 or 12dB boosting range
of adjustment).

A single PP3 (or, optionally-but not essential, two PP3s in the case of
the op-amp solution) should be able to provide dozens, if not hundreds of
hours of fun between changes of battery with such a self contained
boosting amplifier module.

If a more permanent battery-less solution is desired, I'd say the best
option would be to fit it inside the mixer box and provide the additional
phono socket(s) alongside of the existing DIN socket, rather than use a
seperate 9 to 12 volt noise free wallwart psu.

--
Johnny B Good