February 27th 07, 10:13 AM
posted to uk.rec.audio
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Is it valve, or is it SS?
"Don Pearce"
** Dunno just what this Don Dude's angle is here - but that amp
module
uses modern Silicon transistors.
So, it must be a fairly recent of " Pignose Technology" ( I use that
term
very loosely) .
The earlier, almost famous and better sounding examples used Germanium
devices.
AC127 /128 IIRC.
What I mean is that although the amp is solid state, it uses a
topology more normally associated with valve amps.
** It uses the same "topology" as countless, germanium transistor radios of
the 60s and 70s.
Appropriate as it made efficient use of the available battery power.
Only ever seen one guitar amp that used a driver transformer for the output
valves - the 1971 Fender 400PS.
....... Phil
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February 28th 07, 03:14 AM
posted to uk.rec.audio
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Is it valve, or is it SS?
Don Pearce wrote
I have this little battery powered guitar practice amp, made by
Pignose. It sounds amazing - a bit like a Marshall 100 valve amp in
fact, and I could never work out why. These things are used by
plenty
of big names on-stage, as well as plenty more who won't own up to
it.
Anyway, today I had to take the cover off to fix something and I
found
the reason for the meaty sound. It is a mini solid state valve amp
If that's an interstage transformer, then it would be very unusual in
a valve guitar amp. Presumably in the case of the Pignose it performs
the same function as the output transformer: it allows the previous
stage to operate into a higher AC impedance, with a higher voltage
swing.
Would the transistors be able to cope with saturating transformers I
wonder? For good sound to ensue without damage, I suppose max power at
lowest frequency should just push it into the curvy part at the top of
the BH curve. I guess it's the consequent varying load seen by the
transistors that does the trick, and it is interesting to note that
transistor characteristics can be amenable to this kind of thing.
thanks, Ian
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February 28th 07, 07:32 AM
posted to uk.rec.audio
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Is it valve, or is it SS?
On Wed, 28 Feb 2007 03:58:29 +0000, Signal wrote:
(Don Pearce) wrote:
On Mon, 26 Feb 2007 23:04:51 +1100, "Phil Allison"
wrote:
"Don Pearce"
I have this little battery powered guitar practice amp, made by
Pignose. It sounds amazing - a bit like a Marshall 100 valve amp in
fact, and I could never work out why. These things are used by plenty
of big names on-stage, as well as plenty more who won't own up to it.
Anyway, today I had to take the cover off to fix something and I found
the reason for the meaty sound. It is a mini solid state valve amp
http://81.174.169.10/odds/pignose.jpg
Who'd a thought it?
** Dunno just what this Don Dude's angle is here - but that amp module
uses modern Silicon transistors.
So, it must be a fairly recent of " Pignose Technology" ( I use that term
very loosely) .
The earlier, almost famous and better sounding examples used Germanium
devices.
AC127 /128 IIRC.
What I mean is that although the amp is solid state, it uses a
topology more normally associated with valve amps. As such it has many
of a valve amp's characteristics - particularly the curved transfer
function, soft limiting and core saturation. Those are the things that
are heavily exploited in guitar amps to give thickness and weight to
the sound.
I'd never had the cover off this before and I was surprised not to
find a conventional tranny amp (even an IC amp) with some diodes
across the input to give it a bent transfer curve. This is a much more
expensive and better way to achieve the desired effect.
Of course I recognise that this was a conventional way to implement a
"Hi Fi" SS amp back in the sixties - indeed I built a few myself. But
when PNP/NPN matched pairs were a serious proposition and the op-amp
circuit was better understood and accepted, this method died a rapid
and largely unmourned death.
Pearce Consulting
** Consult your Doctor before swallowing what this man says ......
...... Phil
Whatever.
d
Heard the Epiphone Valve Junior?
Don't think so. Tell me.
d
--
Pearce Consulting
http://www.pearce.uk.com
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February 28th 07, 08:34 AM
posted to uk.rec.audio
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Is it valve, or is it SS?
On Wed, 28 Feb 2007 04:14:49 GMT, "Ian Iveson"
wrote:
Don Pearce wrote
I have this little battery powered guitar practice amp, made by
Pignose. It sounds amazing - a bit like a Marshall 100 valve amp in
fact, and I could never work out why. These things are used by
plenty
of big names on-stage, as well as plenty more who won't own up to
it.
Anyway, today I had to take the cover off to fix something and I
found
the reason for the meaty sound. It is a mini solid state valve amp
If that's an interstage transformer, then it would be very unusual in
a valve guitar amp. Presumably in the case of the Pignose it performs
the same function as the output transformer: it allows the previous
stage to operate into a higher AC impedance, with a higher voltage
swing.
I think the interstage transformer is just the way phase splitting was
done when transistor amps used a pair of PNP output transistors and an
output transformer. It makes for very simple, if not terribly linear,
biasing of the output pair.
Would the transistors be able to cope with saturating transformers I
wonder? For good sound to ensue without damage, I suppose max power at
lowest frequency should just push it into the curvy part at the top of
the BH curve. I guess it's the consequent varying load seen by the
transistors that does the trick, and it is interesting to note that
transistor characteristics can be amenable to this kind of thing.
thanks, Ian
I would not have thought that the interstage transformer is in much
danger of saturation. What it does suffer, though, is a net DC bias
from the collector current of the driving transistor. In the output
transformer this is balanced out, and there is no net offsetting
effect.
d
--
Pearce Consulting
http://www.pearce.uk.com
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February 28th 07, 08:28 PM
posted to uk.rec.audio
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Is it valve, or is it SS?
On Wed, 28 Feb 2007 21:11:25 +0000, Signal wrote:
Heard the Epiphone Valve Junior?
Don't think so. Tell me.
It's a little 5w class A valve amp. They have quite a nice tone when
driven by the guitar. Worth checking out..
http://duhvoodooman.com/VJr/VJr_mods.htm
Mmmm... not too convinced at that one. The layout is a total horror,
and despite his claims, the hum is very much there. I'll post a bit of
the Pignose later for comparison.
d
--
Pearce Consulting
http://www.pearce.uk.com
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February 28th 07, 08:46 PM
posted to uk.rec.audio
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Is it valve, or is it SS?
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February 28th 07, 10:51 PM
posted to uk.rec.audio
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Is it valve, or is it SS?
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March 1st 07, 07:04 AM
posted to uk.rec.audio
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Is it valve, or is it SS?
On Wed, 28 Feb 2007 23:51:20 +0000, Signal wrote:
(Don Pearce) wrote:
Heard the Epiphone Valve Junior?
Don't think so. Tell me.
It's a little 5w class A valve amp. They have quite a nice tone when
driven by the guitar. Worth checking out..
http://duhvoodooman.com/VJr/VJr_mods.htm
Mmmm... not too convinced at that one. The layout is a total horror,
and despite his claims, the hum is very much there. I'll post a bit of
the Pignose later for comparison.
d
OK - a quick strum (Gibson SG Standard) he
http://81.174.169.10/odds/pignose.mp3
Yep, I hear some hum / buzz. I like the tone of the Junior a lot
despite that. Yours too, but you can definitely get a much bigger
sound out of your nose... :-) Lay it on it's back and record from a
few feet above.
I'll put up a sample of my Marshall later if time permits..
I used to use the big 8 by 10 cab with a fifty watt head. That made
some noise.
d
--
Pearce Consulting
http://www.pearce.uk.com
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