The performance of an amplifier comes from the way all the components work in
conjunction. Just replacing one item with a 'better' one might simply make the
performance worse...

I think there's a difference between using better componants and 'voicing' an
amp. My experience has been that better componants - caps, resistors etc -
almost always improve the sound - better tone, detail, transparancy etc. Only
at the very end, when the componants are all audiophile quality, do you start
voicing by substituting different tubes, trying different coupling caps (oil v
teflon for instance) and juggling PSU values and componants. With a bit of DIY
experience you learn certain synergies, like using a tube with thin mids like
the 6N30 with a tube with fat mids like the 6N1P, or a warm round plate 6J5G
with a cooler 12B4. All being equal in terms of detail and transparancy, you
can then tune the 'tone' to your preference.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On 13 Jun 2004 17:29:31 GMT, ohawker (Andy
Evans) wrote:

The performance of an amplifier comes from the way all the components work in
conjunction. Just replacing one item with a 'better' one might simply make the
performance worse...

I think there's a difference between using better componants and 'voicing' an
amp. My experience has been that better componants - caps, resistors etc -
almost always improve the sound - better tone, detail, transparancy etc. Only
at the very end, when the componants are all audiophile quality, do you start
voicing by substituting different tubes, trying different coupling caps (oil v
teflon for instance) and juggling PSU values and componants. With a bit of DIY
experience you learn certain synergies, like using a tube with thin mids like
the 6N30 with a tube with fat mids like the 6N1P, or a warm round plate 6J5G
with a cooler 12B4. All being equal in terms of detail and transparancy, you
can then tune the 'tone' to your preference.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

I think you need to be a little careful here. In guitar amplifiers,
with minimal to no feedback, the effect of changing tube manufacturer
is subtle, but well enough documented.

But music reproduction amplifiers with any sort of pretension to high
fidelity are a very different thing. If you can change component types
in a hi fi amp and hear differences, that speaks of quite staggering
incompetence in the design of the amp - it certainly isn't a fit
starting point for any kind of audio project. The must be sufficient
margin in the design of the amp that it can accommodate any make of
valve - any Gm, in other words, without changing its transfer
characteristics. Think of the consequences if it can't achieve that.
As it warms up the sound will change, as the valves age the sound will
change. I guess you just have to hope that somewhere during that
ever-changing cycle the darned thing will hit your favourite tone -
what do you do then? Measure all the valves and try and find more that
perform just the same when you need to change them? Ludicrous.

Add to this, of course the basic inconsistency here of the very idea
of "voicing" an amplifier. An amplifier should not have a voice. It
should be totally self-effacing. Anything less simply gets in the way
of the music. Of course you may actually be into sound effects - in
which case ignore me and go right ahead.

d
Pearce Consulting
http://www.pearce.uk.com

An amplifier should not have a voice.

Maybe in theory, but in practice componants sound different and amps sound
different, and 'voicing' an amp is the common term used in its development.
I've had a few conversations about how Beard amps were 'voiced', for instance,
with one of their chief designers. In terms of valves, the common term 'tube
rolling' would not exist if it were not for the fact that tubes sound different
- swap a 6J5, 6L5, 6C5 and 6P5 and you'll have subtly different sounds, not
even to mention varieties within each type like metal, G and GT, round anode,
flat anode, care in manufacture, production run etc etc. Such threads on tube
rolling and voicing fill the pages of www.audioasylum.com. To suggest that this
representative bunch of electrical engineers, chemical engineers, nuclear
physicists and just plain DIY amp builders with many years of building
experience don't know what they're doing is surely stretching credulity just a
bit too far.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On 13 Jun 2004 19:52:25 GMT, ohawker (Andy
Evans) wrote:

An amplifier should not have a voice.

Maybe in theory, but in practice componants sound different and amps sound
different, and 'voicing' an amp is the common term used in its development.
I've had a few conversations about how Beard amps were 'voiced', for instance,
with one of their chief designers. In terms of valves, the common term 'tube
rolling' would not exist if it were not for the fact that tubes sound different
- swap a 6J5, 6L5, 6C5 and 6P5 and you'll have subtly different sounds, not
even to mention varieties within each type like metal, G and GT, round anode,
flat anode, care in manufacture, production run etc etc. Such threads on tube
rolling and voicing fill the pages of www.audioasylum.com. To suggest that this
representative bunch of electrical engineers, chemical engineers, nuclear
physicists and just plain DIY amp builders with many years of building
experience don't know what they're doing is surely stretching credulity just a
bit too far.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Don't follow your argument. Do you determine facts on the basis of
votes? I believe an American state tried to do that for the value of
pi, until someone with a brain intervened.

And I explained in my post about the kind of amplifiers in which you
could have different sounds depending on the kind of tube. They are
either those that deliberately use the anode slope to establish a
sound - ie guitar amps, or they are incompetently designed hi fi amps.

Which are you talking about?

d
Pearce Consulting
http://www.pearce.uk.com

In article ,
Andy Evans wrote:
To suggest that this representative bunch of electrical engineers,
chemical engineers, nuclear physicists and just plain DIY amp builders
with many years of building experience don't know what they're doing is
surely stretching credulity just a bit too far.

They probably argue about the relative merits of cable too, won't allow
proper testing, but rely on their golden ears...

--
*Honk if you love peace and quiet.

Dave Plowman London SW 12
RIP Acorn

"Keith G" wrote in message
...

"Jim Lesurf" wrote in message
...
In article , Mike Gilmour
wrote:


Thats what I like about old Sci-Fi films, the lab usually has a few
scopes dotted around displaying Lissajous figures - essential for
world
domination. )

I quite like films like "When Worlds Collide" and they cut to "the
computer" and show lots of whirling rods and cams. :-)


...... being operated by a mechanical Olivetti adding machine with the
handle ripped off, like in The Prisoner rerun, a day or two ago!

**Ah, The Prisoner. Now THAT was a great TV show. Along with The Avengers,
it was the pinnacle of Pommy TV (thinks of Mrs Peel and that Lotus).


--
Trevor Wilson
www.rageaudio.com.au

Some discussion of voicing DIY tube amps:

Rumor has it that the Scott company brought professional musicians in house for
auditions when they were voicing the 299B.

I doubt VAC will supply us with their schematics. Besides, their forte is
really in the extensive voicing with parts selection, listening.

I wouldn't bother the -3dB point, just listen. Sometimes for 100ohm cathode
resistor 100uF bypass cap is fine, sometimes 220 and sometimes the 470uF, even
if you use the same time of cap. Use cap value as amp voicing method. If your
amp sound a bit too thin, you may tweak it by a larger cathode cap etc.

(from designer Joe Curcio) Many of us (me included) have wasted time and money
blindly combining the "acclaimed best" of similarly flavored components only to
become dissatisfied with our efforts. And let me add that the power supply
choices, from line filtering thru rectification, DC filtering, bypassing,
regulation, and supply & ground returns, each contribute as much or more to the
recipe. It's easy to see that with all of these contributing elements, it is
very easy to get lost in the spectra of system voicing that can range from
bright and irritating to dull and lifeless.

It's the system synergy thing, one more time. It seems to me that power amps
with "neutral" sonic signatures, like the H/K Cit 2. and AVA FET-Valve that I
own, should be mated with line stages that are SLIGHTLY euphonic (warm) in
character. Net gain should be LOW as the "brutes" are fairly sensitive. I'm
thinking in terms of a 12BH7 (6GU7) in SRPP feeding a 3:1 step down trafo. The
trafo at the O/P reduces net gain, lowers O/P impedance, increases O/P current,
makes the unit non-inverting, and breaks up ground loops. I might as well go
"whole hog" and choke load the SRPP. The opinions of other "inmates" would be
appreciated.

I generally agree with your voicing suggestion but why on earth SRPP?

My Pentode PP amp does not like teflon caps in my preamp, they make the amp
sound thin and edgy. With CCS on the output it got even worse. This is the
complete opposite of my experience with these caps with single ended amps. I
think voicing is very big with an amp this transparent. I now use Jupiter caps
in my preamp - sound very good, in fact about the best I have heard.

I've recently been experimenting with the capacitors in a phono stage. It's a
relatively simple ciruit and has one coupling capacitor and one output
capacitor.

I put Auricaps in both locations and got nice deatail at the expense of some
midrange sweetness. I put Jupiter caps in both locations and got nice sweetness
at the expense of some detail.

I have no place for electrolytics in my amps (with the possible exception of
Blackgates or Elnas) except when absolutely necessary, such as DC filter
supplies for DHTs. Even in DC filament supplies I use Blackgates or Elnas,
Schottky diodes, nice filament chokes and no resistors. I don't know about
mixing caps as you suggest, they might act as mutual filters. You might try
bypassing a Jupiter with one of the small value Russian surplus teflons, that
might give you the warmth and detail you desire. I'm not usually a fan of
bypassing caps in the signal path, but I've heard a couple of amps that sound
great this way. I know of a couple of builders that swear by bypassing a warm
cap like a Jupiter with a teflon. I do like bypassing caps in the power supply,
like an oil with a Solen, and bypassing the Solen with a teflon. I've been
voicing my system for years now.

Hi Ken - can linearity simply be determined the 'old way' by examining the
inverting stage's plus and minus voltage ac-loadline swings around the
operating point on the plate characteristic curves? - is there any point
otherwise besides trial and error to get a specific "voicing"?

I think the Foreplay is the most bang for the buck in the audio world. The nice
thing about building it stock, and adding upgrades later is, that you learn how
certain mods effect the sound. This really helps with voicing projects on down
the line, which I'm pretty sure will happen

I built a fairly straight-forward PP 6B4G amp using Electraprint autoformers to
split phase, based on inmate Scholl's work. 5842 driver. Fixed bias on the
6B4's, LCLC power supply. Vintage Dynaco P-782 power trans, scavanged Sansui
1000A output iron. VERY good sound; I took them to a Chicago Bottlehead
meeting, and they embarrassed some pretty expensive competition. That said, it
has a couple of weaknesses. Coupling cap is critical to voicing the amp. Also,
I always had a bit too much "lushness" in the mid-bass. I ended up putting in
Electraprint interstage transformers; sounds better to my ears (tho I miss that
false "lush").

I drove a dual 211 in long tailed pair, PSRejection mode for some years using a
6SN7 pair as Mu Follower and listened to fast and clean sound.
I then upgraded it to a 2A3 working into a Tamura NC14 IST, 5K/5K. The change
in sonics was tremendous. The interesting bit was that I ran this on the right
channel and just the 2A3 with 5K OPT on the left to ensure that the voicing was
the same. I haven't found anyone who could tell the difference yet.
Upgrading the fixed bias to 195 volts runs an 845 quite nicely except that I
did not like the sound and went back to the 211. Your earlier comments re
drivers not being as good as the real sound of a 300B stand up very well. Once
you get the driver stage right, big drive, substantial current, the tube sound
vanishes and the power tube becomes not much more than an impedance buffer with
a small sonic contribution.

I've used Rikens, carbon comps like the Allen Bradleys, cheapie Radio Shack
carbon films, Philips and NTE metal films, and 'no-name' metal oxides in my DIY
amps.

My personal preferences for resistors are in the order above. The Rikens are
best IMO, with good detail yet a nice warm sound, carbon comps and the RS
carbon films are about equal, the Philips and NTE metals are okay but too
"cold" sounding for many circuits (though they are nicely detailed), and
'no-name' metal oxides are completely unacceptable due to their very cold and
grainy character. IMHO the most important resistors in common cathode circuits
are the plate load resistors and the gridstoppers. For a nice warm sound, I'd
go carbon (Riken, RS carbon film, or carbon comp) there. However, you can try
the Philips/NTE metal films as plate load resistors if you want a more detailed
sound. I will admit to using a pair of 150 ohm Philips ECG metal films as plate
loads at top of the cascode in my 6DJ8/6922 amp to get a little more detail, so
they are indeed useable in voicing an amp that's a little too warm and fuzzy.

In trying to address the limitations of the original Joe Curcio designed Daniel
and preserve and improve on its strength we tried many tube (and solid state
for that matter) "gain blocks" including, SRPP, cascade, cascode, MU Follower,
differential amplifier, as well as other more unconventional topologies and
catalogued their signature "voicing" colorations. Many circuits whose
theoretical and measured performance are exceptional failed to sound musical
and realistic losing depth and skewing spectral balance. Some sounded outright
harsh; similar to second generation solid state circuitry. A few were
outstanding in one area (i.e. dynamics) while mediocre in another (i.e. image).
As a result, we have developed a portfolio of "select" topologies that are
applied to meet the requirements. We have realized excellent results with anode
followers, optimized cascodes, and a unique triode / Junction FET hybrid
deployed in our Daniel II reference preamplifier. It's measured specifications
are unparalleled but more importantly, it provides a complete sense of realism
both in spectral balance and holographic imaging.




=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

In article , Andy Evans wrote:
Some discussion of voicing DIY tube amps:
snip

Interesting thread. I guess it illustrates how far away valve/tube
amplifiers still are from the ideal of just being "an amplifier."
Show me two amplifiers that (really do) sound different and I'll show
you *at least* one which is not behaving as ideally it should.

Loudspeakers, imperfect mechanical transducers that they are, are like
that still. I suspect the same is true of vinyl and vinyl reproduction
kit (but I have no recent experience).

However, my own view is that for some time the state of the art in other
audio components (including cables) is such that ideality is the right
and obvious goal to be approached. Naturally, if anyone still wants to
select or tweak an amplfier to tune the "voice" of his/her audio systems
then that's fine by me. After all the object is one of enjoying the
result (and/or the tweaking process).

Indeed, if valve/tube amplifiers did all sound the same then a few in the
audio industry would be out of a job since the amount of money coming
into that sector would drop significantly. So the preservation of a
"voicing" sector through the mutual interests of producers and consumers
seems inevitable.

Long live choice.

--
John Phillips

On 13 Jun 2004 23:23:05 GMT, ohawker (Andy
Evans) wrote:

Some discussion of voicing DIY tube amps:

Rumor has it that the Scott company brought professional musicians in house for
auditions when they were voicing the 299B.

I doubt VAC will supply us with their schematics. Besides, their forte is
really in the extensive voicing with parts selection, listening.

I wouldn't bother the -3dB point, just listen. Sometimes for 100ohm cathode
resistor 100uF bypass cap is fine, sometimes 220 and sometimes the 470uF, even
if you use the same time of cap. Use cap value as amp voicing method. If your
amp sound a bit too thin, you may tweak it by a larger cathode cap etc.

(from designer Joe Curcio) Many of us (me included) have wasted time and money
blindly combining the "acclaimed best" of similarly flavored components only to
become dissatisfied with our efforts. And let me add that the power supply
choices, from line filtering thru rectification, DC filtering, bypassing,
regulation, and supply & ground returns, each contribute as much or more to the
recipe. It's easy to see that with all of these contributing elements, it is
very easy to get lost in the spectra of system voicing that can range from
bright and irritating to dull and lifeless.

It's the system synergy thing, one more time. It seems to me that power amps
with "neutral" sonic signatures, like the H/K Cit 2. and AVA FET-Valve that I
own, should be mated with line stages that are SLIGHTLY euphonic (warm) in
character. Net gain should be LOW as the "brutes" are fairly sensitive. I'm
thinking in terms of a 12BH7 (6GU7) in SRPP feeding a 3:1 step down trafo. The
trafo at the O/P reduces net gain, lowers O/P impedance, increases O/P current,
makes the unit non-inverting, and breaks up ground loops. I might as well go
"whole hog" and choke load the SRPP. The opinions of other "inmates" would be
appreciated.

I generally agree with your voicing suggestion but why on earth SRPP?

My Pentode PP amp does not like teflon caps in my preamp, they make the amp
sound thin and edgy. With CCS on the output it got even worse. This is the
complete opposite of my experience with these caps with single ended amps. I
think voicing is very big with an amp this transparent. I now use Jupiter caps
in my preamp - sound very good, in fact about the best I have heard.

I've recently been experimenting with the capacitors in a phono stage. It's a
relatively simple ciruit and has one coupling capacitor and one output
capacitor.

I put Auricaps in both locations and got nice deatail at the expense of some
midrange sweetness. I put Jupiter caps in both locations and got nice sweetness
at the expense of some detail.

I have no place for electrolytics in my amps (with the possible exception of
Blackgates or Elnas) except when absolutely necessary, such as DC filter
supplies for DHTs. Even in DC filament supplies I use Blackgates or Elnas,
Schottky diodes, nice filament chokes and no resistors. I don't know about
mixing caps as you suggest, they might act as mutual filters. You might try
bypassing a Jupiter with one of the small value Russian surplus teflons, that
might give you the warmth and detail you desire. I'm not usually a fan of
bypassing caps in the signal path, but I've heard a couple of amps that sound
great this way. I know of a couple of builders that swear by bypassing a warm
cap like a Jupiter with a teflon. I do like bypassing caps in the power supply,
like an oil with a Solen, and bypassing the Solen with a teflon. I've been
voicing my system for years now.

Hi Ken - can linearity simply be determined the 'old way' by examining the
inverting stage's plus and minus voltage ac-loadline swings around the
operating point on the plate characteristic curves? - is there any point
otherwise besides trial and error to get a specific "voicing"?

I think the Foreplay is the most bang for the buck in the audio world. The nice
thing about building it stock, and adding upgrades later is, that you learn how
certain mods effect the sound. This really helps with voicing projects on down
the line, which I'm pretty sure will happen

I built a fairly straight-forward PP 6B4G amp using Electraprint autoformers to
split phase, based on inmate Scholl's work. 5842 driver. Fixed bias on the
6B4's, LCLC power supply. Vintage Dynaco P-782 power trans, scavanged Sansui
1000A output iron. VERY good sound; I took them to a Chicago Bottlehead
meeting, and they embarrassed some pretty expensive competition. That said, it
has a couple of weaknesses. Coupling cap is critical to voicing the amp. Also,
I always had a bit too much "lushness" in the mid-bass. I ended up putting in
Electraprint interstage transformers; sounds better to my ears (tho I miss that
false "lush").

I drove a dual 211 in long tailed pair, PSRejection mode for some years using a
6SN7 pair as Mu Follower and listened to fast and clean sound.
I then upgraded it to a 2A3 working into a Tamura NC14 IST, 5K/5K. The change
in sonics was tremendous. The interesting bit was that I ran this on the right
channel and just the 2A3 with 5K OPT on the left to ensure that the voicing was
the same. I haven't found anyone who could tell the difference yet.
Upgrading the fixed bias to 195 volts runs an 845 quite nicely except that I
did not like the sound and went back to the 211. Your earlier comments re
drivers not being as good as the real sound of a 300B stand up very well. Once
you get the driver stage right, big drive, substantial current, the tube sound
vanishes and the power tube becomes not much more than an impedance buffer with
a small sonic contribution.

I've used Rikens, carbon comps like the Allen Bradleys, cheapie Radio Shack
carbon films, Philips and NTE metal films, and 'no-name' metal oxides in my DIY
amps.

My personal preferences for resistors are in the order above. The Rikens are
best IMO, with good detail yet a nice warm sound, carbon comps and the RS
carbon films are about equal, the Philips and NTE metals are okay but too
"cold" sounding for many circuits (though they are nicely detailed), and
'no-name' metal oxides are completely unacceptable due to their very cold and
grainy character. IMHO the most important resistors in common cathode circuits
are the plate load resistors and the gridstoppers. For a nice warm sound, I'd
go carbon (Riken, RS carbon film, or carbon comp) there. However, you can try
the Philips/NTE metal films as plate load resistors if you want a more detailed
sound. I will admit to using a pair of 150 ohm Philips ECG metal films as plate
loads at top of the cascode in my 6DJ8/6922 amp to get a little more detail, so
they are indeed useable in voicing an amp that's a little too warm and fuzzy.

In trying to address the limitations of the original Joe Curcio designed Daniel
and preserve and improve on its strength we tried many tube (and solid state
for that matter) "gain blocks" including, SRPP, cascade, cascode, MU Follower,
differential amplifier, as well as other more unconventional topologies and
catalogued their signature "voicing" colorations. Many circuits whose
theoretical and measured performance are exceptional failed to sound musical
and realistic losing depth and skewing spectral balance. Some sounded outright
harsh; similar to second generation solid state circuitry. A few were
outstanding in one area (i.e. dynamics) while mediocre in another (i.e. image).
As a result, we have developed a portfolio of "select" topologies that are
applied to meet the requirements. We have realized excellent results with anode
followers, optimized cascodes, and a unique triode / Junction FET hybrid
deployed in our Daniel II reference preamplifier. It's measured specifications
are unparalleled but more importantly, it provides a complete sense of realism
both in spectral balance and holographic imaging.




=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

The moral of this tale is that if you want to make sure nobody can
disagree with you, just say stuff that is devoid of any meaning.

d
Pearce Consulting
http://www.pearce.uk.com

In article , Keith G
wrote:

"Jim Lesurf" wrote in message
...


The performance of an amplifier comes from the way all the components
work in conjunction. Just replacing one item with a 'better' one might
simply make the performance worse...


Indeed, 'upset the balance', as it were. In which case one would need to
reverse the changes or move onto different components, which I guess is
pretty much how valve amplifier designs are finalised anyway.

There is a state in the process of devolpment and design which I tend to
call 'lost in space'. :-)

This is where you have a number of variables (choice of component types,
choice of values, slight topology changes, etc) and want to 'optimise' a
design. Since they all tend to interact, if you just try changing one thing
or another you can end up 'wandering about' in terms of the state of the
unit. With luck (and time!) you can end up in a place which seems OK.
However you may then have no real idea *why*. Nor know that a better result
might be nearby, but you never wandered past it...

I must admit that a lot of what I've read about the process of people
trying 'different' components to see what they does sound a bit like the
above to me.

Part of the appeal of valve kit to some people is that it can be
'tweaked' in a comparatively easy way, making the amplifier a more
significant contributor to the overall sound characteristics of a
'hi-fi' system. Not that everybody thinks that is necessarily a good
thing - I've been so pleased with the sound I get using my own kit amp,
I've never been tempted to fiddle with it......

My worries about the above a

1) The 'lost in space' problem. Might be a 'better' arrangement that could
have been cheaper and easier if you'd known.

2) People then not knowing that the resulting amp is unstable or marginal,
or has a reduced life or safety margin. (I am particularly worried about
this when a design is developed for kit use as the original development may
then not have covered properly the effects of normal component variations.
I recall WW kit designs being called 'Worked Wunce' rather than 'Wireless
World' by some professionals. :-) )

For the above reasons my own inclination is to treat the system as a whole
and do relevant measurements as well as listen. However I am unsure how
many DIY or kit builders do this.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html