Looking for a small bit of gain
 

Bah humbug.
It just seems to be like building a floating hotel and using it as a garden
shed.
Brian

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"Don Pearce" wrote in message
...
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.

d

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Looking for a small bit of gain
 

OK look into that. I wonder what current it uses, Might well run on a pp3
battery then.
Brian

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"Woody" wrote in message
...
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....


--
Woody

harrogate3 at ntlworld dot com

Looking for a small bit of gain
 

On Wed, 5 Jul 2017 08:31:34 +0100, "Brian Gaff"
wrote:

Bah humbug.
It just seems to be like building a floating hotel and using it as a garden
shed.
Brian

Those days are long gone. Op-amps are basic building blocks these
days. They are much better characterized than individual transistors,
and generally come out as a cheaper and easier option.

d

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Looking for a small bit of gain
 

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

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Looking for a small bit of gain
 

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.

d

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Looking for a small bit of gain
 

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'.

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

--
Trevor Wilson
www.rageaudio.com.au

Looking for a small bit of gain
 

In article , Don Pearce
wrote:

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.

I altered the circuit. As supplied the components and diagram give some
gain. In effect its a cheap way of getting a set of components and board
for a stereo gain block.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Looking for a small bit of gain
 

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.

--
*Wood burns faster when you have to cut and chop it yourself.

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

Looking for a small bit of gain
 

In article , Dave Plowman (News)
wrote:

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.


The HeadDAC2 situation has the max input level set by the DAC I chose.
Which is also powered by the same circa 5V line. It doesn't clip early in
practice.

In other circumstances I prefer a twin-rail. So I've used the same kit as a
basis for a heaphone amp and HF filter for my ARMX6, but in this case using
+/- 5V. Again, I know what the max input level will be.

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

That really depends on factors like if there is an active gain stage before
any volume controls and what else might limit the max input, what the
clipping behaviour is like, etc. The problem here in general commercial kit
is to guess what the user will connect. I've had a case of someone
connecting mains power to a LS output, which isn't what the designer
expects to have to cater for! 8-]

The 33 also comes from an age well before the CD audio standard of 2V
signals. But does offer the magic of the 'keymatic'...

FWIW In the Armstrong 700 preamp I used +/- 21V rails and had a volume
control before the active stages. (Except for RIAA, which also has +/- 21V
rails.)

Sadly that didn't stop a reviewer talking nonsense about its clipping
levels. But then, that's magazine reviewing, innit! 8-]

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Looking for a small bit of gain
 

On Wed, 05 Jul 2017 13:23:10 +0100, "Dave Plowman (News)"
wrote:

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.

This is true, but given that the signal is too low, it is probably
reasonably safe to do this. I have to say, though, I would not run it
off 5V - I would give it at least +/- 12V.

d

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