Fred Forssell JMP-1 micpreamp

[Frederick]

Hi everybody!

I'm thinking about buying a Forssell JMP-2 (two channel) micpreamp. It
seems
like a good micpreamp, I just wonder if any of you guys have listen to
it?
It is as good as it seems to be and how does it compare to other
micpres?

I'm planning to build a really good powersupply for it. And I'm going
to put two UTC trannies on the inputs.

Any info is appreciated


Cheers
Frederick
Ninja Production

[Jim Kollens]

James Boyk: << And the reason for putting xfmrs. on the input of this very
quiet
transformerless unit is...? >>

I can only guess. Nonetheless, I find it interesting that the Pendulum unit
that I just bought does the same thing (the ES-8). Greg Gualtieri, the
designer, seems to be a firm believer in transformer-less designs. The ES-8
has no transformer on the output but does on the input, a Jensen. I also find
it interesting that the manual suggests you take particular care in isolating
the chassis from the rack. The ES-8 eight is an exquisite piece but I must
confess that I would be a bit more comfortable with a transformer at the
output.

[James Boyk]

Jim Kollens wrote: > ...Nonetheless, I find it interesting that the
Pendulum unit
that I just bought does the same thing (the ES-8). Greg Gualtieri, the
designer, seems to be a firm believer in transformer-less designs. The ES-8
has no transformer on the output but does on the input, a Jensen.

Then it would seem he is *not* a believer in xfmr-less designs, eh?


> ...The ES-8 eight is an exquisite piece but I must confess that I would
be a bit more comfortable with a transformer at the output.

May I ask why?

A good xfmr. is far from the worst thing in the world, sonically
speaking; but I have yet to hear one that doesn't degrade the sound.
(But let's not start this up again; it was beaten to death in a recent
thread.)

James BOyk

[Jay - atldigi]

In article >,
(Jim Kollens) wrote:

> James Boyk: << And the reason for putting xfmrs. on the input of this
> very quiet transformerless unit is...? >>
>
> I can only guess.

Maybe he wants more color and this particular transformer has a sound
that pleases him. Transformers can be a huge part of a warm sound. I'd
probably be looking at less neutral pres if I wanted color, but then
again, a neutral pre will pass the sound of that transformer quite
accurately, so maybe... Heck, why don't we ask him? Why the transformers?

By the way, Fred's gear rocks! I wish he'd make a mastering EQ. I just
keep saying this hoping that he'll get sick of hearing it and finally
make one to shut us all up. Pretty please?

--
Jay Frigoletto
Mastersuite
Los Angeles
www.promastering.com

[Jim Kollens]

James Boyk: >A good xfmr. is far from the worst thing in the world, sonically
>speaking; but I have yet to hear one that doesn't degrade the sound.
>(But let's not start this up again; it was beaten to death in a recent
>thread.)
>

Yes, let's not and I've probably said more than I should already. Me and my
big mouth.

[James Boyk]

Frederick wrote:> I'm going to make the trannies switchable in and out of the signalpath,

I suggest that you make that "solderable into and out of," unless you
have some truly remarkable switches that won't disturb a mike-level signal.


> I listened to a micpreamp with UTC LS-30 transformers on the inputs a while ago and thought it sounded fabolous.

OK, but I hope you understand that you were hearing Preamp+Xfmr. The
same Xfmr. with a different Preamp may make for quite a different sonic
result. If you liked what you heard so much, why not buy exactly the
same thing?

(I don't know the LS-30. The LS's I'm familiar with are LS-10, -10X, -12
and -12X. (The X stands for extra shielding; and it's interesting to
note that these versions have somewhat lower overload levels; 2 dB
lower, if memory serves. One infers that those large cases really are
packed full of transformer!)

James Boyk

[Mike Rivers]

In article > writes:

> And the reason for putting xfmrs. on the input of this very quiet
> transformerless unit is...?

It's those pesky microphones. Golden ears in non-blind, totally
biased, but just plain "feel good sound good" testing have shown that
there are more microphones in the world that sound better when loaded
with a transformer than when loaded with a capacitor and a few diode
junctions. The preamp manufacturers who care that the customer hears a
definite improvement in "sound quality" (whatever that means, other
than lower noise), since they don't know what microphone(s) the
customer will use, can often improve their odds using a transformer.

And what's the point of having a mic preamp if you aren't going to
connect a microphone to it?

Not to say that this "principle" hasn't been mis-applied, that preamps
have been made with not-so-hot transformers at the input, and that
they might sound better without the transformers. But we're talking
quality products here, where the designer will take as much care in
selecting the transformer as he does in selecting every other
component.



--
I'm really Mike Rivers - )

[Scott Dorsey]

> Nonetheless, I find it interesting that the Pendulum unit
>that I just bought does the same thing (the ES-8). Greg Gualtieri, the
>designer, seems to be a firm believer in transformer-less designs. The ES-8
>has no transformer on the output but does on the input, a Jensen.

Doesn't sound very firm to me.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[James Boyk]

Jay - atldigi wrote: > That wouldn't be terribly convenient.

True, true. But what does convenience have to do with the best sound
quality? Bad switch contacts can Really screw up the sound; and I doubt
that he'll find good ones.

James Boyk

[Frederick]

James Boyk > wrote in message >...
> Frederick wrote:> I'm going to make the trannies switchable in and out of the signalpath,
>
> I suggest that you make that "solderable into and out of," unless you
> have some truly remarkable switches that won't disturb a mike-level signal.

I'm well aware of that problem so I'll probably use a mute switch on
the output.

> > I listened to a micpreamp with UTC LS-30 transformers on the inputs a while > > ago and thought it sounded fabolous.
>
> OK, but I hope you understand that you were hearing Preamp+Xfmr.

Naturally...

> The same Xfmr. with a different Preamp may make for quite a different sonic
> result. If you liked what you heard so much, why not buy exactly the
> same thing?

Well, I have the schematics for the micpre with the fabolous sound
aswell, but my guess is that the Forssell JMP-1 will sound ever better
cause it seems to be a superior design. So I will try it first.

> (I don't know the LS-30.

It's a very fine tranny, I'd tell you that. :-D

Sort of looking for a good output tranny, maybe an API AP2503 or
something like it for colour. Or a Lundahl for a more transparent
sound.
If any of you guys have hands on experience with output transformers
and wanna share some of your thoughts about it, then I'd really
appreciate it.

Just to make things clear, I do love both transformersless micpreamps,
like DACS, and transformerbalanced micpreamps like API. And of course
tubedesigns like Telefunken V72. They are all great designs but for
different applications.


Cheers
Frederick

[James Boyk]

Frederick wrote: > I'm well aware of that problem so
I'll probably use a mute switch on the output.


Different problem. I'm talking about sonic degradation through switch
contacts.



> Well, I have the schematics for the micpre with the fabolous sound
> aswell, but my guess is that the Forssell JMP-1 will sound ever better
> cause it seems to be a superior design. So I will try it first.

And you're therefore going to degrade this better-sounding preamp with a
transformer? Well, if this pleases you, by all means do it.


> Sort of looking for a good output tranny, maybe an API AP2503 or
> something like it for colour. Or a Lundahl for a more transparent
> sound.

You get a transparent sound by using No transformer unless there's some
reason you Must use one.

With respect, I suggest you sometimes try listening to live
unadulterated Music and spend all this energy you have in trying to
capture its combination of Power and Delicacy.


James Boyk

[Rifa Roederstein]

You might want to try here. http://nanaimo.ark.com/~pat/
I've built a few tube preamps and am working on a couple preamps using
the Millennia Media MM-990 JFET module. He has alot of nice vintage
transformers and won't sell you any scrap. It's high end though so
it's
reasonable, but not cheap. He doesn't have alot of time to hold your
hand through a project, but he's treated me very well. I went for top
of the line components and am very happy with them. Good Luck!

(Frederick) wrote in message >...
> >Maybe he wants more color and this particular transformer has a sound
> >that pleases him. Transformers can be a huge part of a warm sound.
> I'd
> >probably be looking at less neutral pres if I wanted color, but then
> >again, a neutral pre will pass the sound of that transformer quite
> >accurately, so maybe... Heck, why don't we ask him? Why the
> transformers?
>
> Well, I'm going to make the trannies switchable in and out of the
> signalpath, so that I can use the more transparent tranformerless
> sound aswell. I guess I want a little bit of both worlds.
> I listened to a micpreamp with UTC LS-30 transformers on the inputs a
> while ago and thought it sounded fabolous. And today I found two UTC
> LS-30 in mint condition on Ebay. So I bought them and soon I'm going
> to try them out.
> It might be better to use them along with a more colored micpre design
> (to really get a coloured sound), but I'll probably try the Forssell
> design first.
>
> I'm also looking for good output transformer´s. Any tip is
> appreciated.
> I guess I'm looking for something in the Neve or API style. But
> without the high pricetag, if possible.
>
> Anyway, I'm no micpre designer, I just like experimenting and see/hear
> what the result will be. And if the first two channels turn out well,
> then I'll build me a copule of more channels.
>
>
> Cheers
> Frederick

[James Boyk]

JB wrote: such a statement about "microphones" and "transformers" is
surely too broad.

Mike Rivers wrote: > Broad, but true.

You said, "...there are more microphones in the world that sound better
when loaded with a transformer than when loaded with a capacitor and a
few diode junctions...." By "a few diode junctions," I take it you mean
an input transistor. I don't know how many mike models exist; let's say
500; surely the actual number is higher. Are you really saying then that
you've personally done the comparison on at least 251 models? I doubt
it. Remember, it would have to be with levels and polarity matched.

James Boyk

[Chris Hornbeck]

On Sat, 05 Jul 2003 17:48:05 -0700, James Boyk >
wrote:

>And the reason for putting xfmrs. on the input of this very quiet
>transformerless unit is...?

My first guess would be bandlimiting, protection from RFI, etc.
Out-of-band signals cause in-band degradation in lots of places,
especially phono equalizers, DAC's and mic preamps.


Chris Hornbeck,
guyville{at}aristotle{dot}net
question Authority

[James Boyk]

Chris Hornbeck wrote:
> My first guess would be bandlimiting, protection from RFI, etc.
> Out-of-band signals cause in-band degradation in lots of places,
> especially phono equalizers, DAC's and mic preamps.

Boy, there are a lot better ways to do those things w/out degrading the
sound.

James Boyk

[Jay - atldigi]

In article >, James Boyk >
wrote:

> Jay - atldigi wrote: > That wouldn't be terribly convenient.
>
> True, true. But what does convenience have to do with the best sound
> quality? Bad switch contacts can Really screw up the sound; and I doubt
> that he'll find good ones.
>
> James Boyk
>

I wouldn't second guess an extremely bright designer like Fred on his
design, so I wouldn't personally add transformers. If it was for an
interesting experiment in color, then the "best sound quality"
terminology is either up for grabs or not really relevant. It looks like
he's going for a particular sound and not clean neutrality. That's cool.
Sometimes color is great. It sounds like he's after a different goal
from you in this particular project. In that light, I say get the best
switch you can (those buggers can get expensive) and have fun
experimenting with the project. I wouldn't do anything that would alter
the pre so much that I couldn't get it back to ground zero and enjoy it
as Forssell intended it. But maybe he already has a Martech and a
Millennia sitting around for neutrality. Heck, a couple transformers on
a Forssell and some degradation may be just what the doctor ordered to
widen the available pallette. If he asked for the best pre for a
delicate classical date, I may offer a different opinion.

--
Jay Frigoletto
Mastersuite
Los Angeles
www.promastering.com

[Arny Krueger]

"James Boyk" > wrote in message


> Mike Rivers wrote: > ...more microphones ...sound better when loaded
> with a transformer than when loaded with a capacitor and a few diode
> junctions.

> Good reason to use tubes.

Fallacious logic, to say the least.

> But seriously, folks, such a statement about "microphones" and
> "transformers" is surely too broad.

It's open to charges of excess simplicity. For example, transformers are
just matching devices. A SS preamp with a transformer still loads the mic
with R's, C's and semiconductors, only with the transformer acting as a
matching device.

It's also open to charges of excess complexity, given how many mics
themselves have transformers in them.

It's also open to massive charges of utter meaninglessness, given there is
no general agreement on what "sound(s) better" means. The closest definition
of "sound(s) better" with general agreement that we have relates to sonic
accuracy, which means no inherent coloration at all. It seems that the
closer you get to the sound source or the ear, the tougher the sonic
accuracy model gets to apply.

[Mike Rivers]

In article > writes:

> In article >, James Boyk >
> wrote:
> > I suggest that you make that "solderable into and out of," unless you
> > have some truly remarkable switches that won't disturb a mike-level
> > signal.
>
> That wouldn't be terribly convenient. He should just take care in the
> selection of switches, and the actual switching while in use to avoid
> the problems that could occur

The tweako-audiophile stuff that has switches in the signal path often
uses sealed reed relays. They won't disturb a mic-level signal. Of
course you could expect some change and maybe a pop when switching
inductance in and out, so you'd want to mute the output momentarily.
It could be done easily with whatever controls the relays.


--
I'm really Mike Rivers - )

[James Boyk]

Fletcher wrote:
> You keep going on about 'degrading' the audio... ace, if it sounds good, it
> is good... test measurements be damned.

....which is the position I've espoused in teaching and writing for
decades. Degrading the sound is of course what I'm talking about.

James Boyk

[Fletcher]

James Boyk wrote:

> Fletcher wrote:
> > You keep going on about 'degrading' the audio... ace, if it sounds good, it
> > is good... test measurements be damned.
>
> ...which is the position I've espoused in teaching and writing for
> decades. Degrading the sound is of course what I'm talking about.

Then you should reconsider your 'transformers are evil' thing... *many*
transformers sound great, not all, but enough so there is absolutely no reason
why they shouldn't be considered.
--
Fletcher
Mercenary Audio
TEL: 508-543-0069
FAX: 508-543-9670
http://www.mercenary.com
"this is not a problem"

[Mike Rivers]

In article > writes:

> It's open to charges of excess simplicity. For example, transformers are
> just matching devices. A SS preamp with a transformer still loads the mic
> with R's, C's and semiconductors, only with the transformer acting as a
> matching device.

The transformer is also an inductor, something that's almost
negligable in a transformerless input stage.

> It's also open to massive charges of utter meaninglessness, given there is
> no general agreement on what "sound(s) better" means. The closest definition
> of "sound(s) better" with general agreement that we have relates to sonic
> accuracy, which means no inherent coloration at all. It seems that the
> closer you get to the sound source or the ear, the tougher the sonic
> accuracy model gets to apply.

This is true, and only people who are trying to prove a point (I'm not
the only one who hasn't listened to every mic with every preamp and
taken good notes) really care to argue it. There are a few aboslute truths
however:

1. If we have a choice, we use what we think we like at the time we're
making the choice. (it might not be the same choice we'd make another
day but by then it's too late)

2. If we don't have a choice, we use what we have and either live with
it or decide that it absolutely won't work and go get something else.

3. It's very easy to accumulate too many combinations to make the
optimum choice, but it's easy to narrow down the selection based on
experience, which in itself involves personal taste and opinions.

4. Nobody is ever completely happy when it comes to sound.



--
I'm really Mike Rivers - )

[Scott Dorsey]

James Boyk > wrote:
>Chris Hornbeck wrote:
>> My first guess would be bandlimiting, protection from RFI, etc.
>> Out-of-band signals cause in-band degradation in lots of places,
>> especially phono equalizers, DAC's and mic preamps.
>
>Boy, there are a lot better ways to do those things w/out degrading the
>sound.

I'm not sure there are. I really don't like the coloration transformers
add, but I'm often willing to put up with it because there is just no other
way to get that kind of CMRR. You can deal with outrageous ground
differences between gear using transformers and in field situations that
is sadly a requirement.

I'm talking about sixty or seventy volt ground faults... not the kind of
thing that typical active inputs deal with very well.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[James Boyk]

>>Chris Hornbeck:
>>>My first guess would be bandlimiting, protection from RFI, etc.
>>>Out-of-band signals cause in-band degradation in lots of places,
>>>especially phono equalizers, DAC's and mic preamps.

JB: Boy, there are a lot better ways to do those things w/out degrading
the sound.

Scott Dorsey:
> I'm not sure there are. I really don't like the coloration transformers
> add, but I'm often willing to put up with it because there is just no other
> way to get that kind of CMRR. You can deal with outrageous ground
> differences between gear using transformers and in field situations that
> is sadly a requirement.
>
> I'm talking about sixty or seventy volt ground faults... not the kind of
> thing that typical active inputs deal with very well.

But Chris didn't mention CMRR or ground-potential differences. He
mentioned bandlimiting, which can be done with a shunt cap; and
protection from RFI, which can be done with good shielding practice &
ferrite beads (possibly not ideally, but still quite powerfully).

If you have 60- or 70-volt differences in ground potential, don't you
have a defective power transformer somewhere?

James Boyk

[Fletcher]

James Boyk wrote:

> One thing I've discovered that's kind of interesting is that I can tell
> when a device has a bad transformer just by putting a finger on the
> chassis. It feels to me as though it's vibrating or trembling. Other
> people don't seem to feel this.

So now power transformers degrade the audio as well? Have you ever
considered listening as well as measuring?
--
Fletcher
Mercenary Audio
TEL: 508-543-0069
FAX: 508-543-9670
http://www.mercenary.com
"this is not a problem"

[Arny Krueger]

"Fletcher" > wrote in message
...
> James Boyk wrote:
>
> > Fletcher wrote:
> > > You keep going on about 'degrading' the audio... ace, if it sounds
good, it
> > > is good... test measurements be damned.
> >
> > ...which is the position I've espoused in teaching and writing for
> > decades. Degrading the sound is of course what I'm talking about.
>
> Then you should reconsider your 'transformers are evil' thing... *many*
> transformers sound great, not all, but enough so there is absolutely no
reason
> why they shouldn't be considered.

There's no doubt in my mind that a few DBTs would straighten Boyk out. Too
bad he's allergic.

[Arny Krueger]

"Fletcher" > wrote in message
...
> James Boyk wrote:
>
> > One thing I've discovered that's kind of interesting is that I can tell
> > when a device has a bad transformer just by putting a finger on the
> > chassis. It feels to me as though it's vibrating or trembling. Other
> > people don't seem to feel this.
>
> So now power transformers degrade the audio as well? Have you ever
> considered listening as well as measuring?

The slings and arrows of listening with one's eyes open...

[Arny Krueger]

"James Boyk" > wrote in message
...

> It's hilarious that you attack me for supposedly espousing measurement
> over listening.

Except you obviously don't just listen James.

> You've got the wrong guy, as any of the hundreds of
> students in my Caltech course, or the people at Sheffield Lab, or at
> Harmonia Mundi USA, or many others could tell you. I'm the guy who's
> been espousing listening as the sine qua non of audio evaluations for
> decades; and I've been espousing it in my work as engineer/producer, as
> teacher, researcher, writer and consultant.

Except you obviously don't just listen James.

> No one could possibly get
> this wrong who was paying the slightest attention. Therefore, I suggest
> a process: FIRST, read what I say. SECOND, read it out loud. THIRD,
> think about it. FOURTH, write a response if necessary. This will avoid
> attacking me for things I never said. For instance, In my post above,
> where did I say a word about anything degrading the audio? What I wrote
> had NOTHING TO DO with the audio.

Except you obviously don't just listen James.

[Mike Rivers]

In article > writes:

> One thing I've discovered that's kind of interesting is that I can tell
> when a device has a bad transformer just by putting a finger on the
> chassis. It feels to me as though it's vibrating or trembling.

Mechanical vibration of transformer windings can indeed be a source of
acoustic noise. I suppose that it's possible to feel the vibration
before you can hear it. But usually it's the power transformer that's
got the loose windings or core laminations. Have you been able to
isolate the "feel" of a signal transformer and feel it vibrate along
with the audio?


--
I'm really Mike Rivers - )

[Fletcher]

James Boyk wrote:

> James Boyk wrote: One thing I've discovered that's kind of
> interesting is that I can tell when a device has a bad
> transformer just by putting a finger on the chassis. It
> feels to me as though it's vibrating or trembling. Other
> people don't seem to feel this.
>
> Fletcher wrote:
> So now power transformers degrade the audio as well? Have you ever
> considered listening as well as measuring?
>
> It's hilarious that you attack me for supposedly espousing measurement
> over listening.

In this particular post you indeed didn't state that 'transformers degrade
the audio'... but you have indeed stated that in several other posts [do I
really need to dredge up examples... it's kind of a waste of our time ain't
it?].


> You've got the wrong guy, as any of the hundreds of
> students in my Caltech course, or the people at Sheffield Lab, or at
> Harmonia Mundi USA, or many others could tell you. I'm the guy who's
> been espousing listening as the sine qua non of audio evaluations for
> decades; and I've been espousing it in my work as engineer/producer, as
> teacher, researcher, writer and consultant.

Right... sure. But transformers are evil... gotcha.

> No one could possibly get
> this wrong who was paying the slightest attention. Therefore, I suggest
> a process: FIRST, read what I say. SECOND, read it out loud. THIRD,
> think about it. FOURTH, write a response if necessary. This will avoid
> attacking me for things I never said. For instance, In my post above,
> where did I say a word about anything degrading the audio?

As I'm obviously a moron, you did say at one point during this thread that
'transformers degrade the audio', didn't you?

> What I wrote
> had NOTHING TO DO with the audio.
>

Thank's for your resume... as well as the advice on how to read and process
information. It shall be filed with the previous transformers and switches
degrade the audio comments. The inference was that you, oh zen master of
all audio purism, can tell a bad transformer by touch... when coupled with
the previous transformers are the work of Satan comments... it's not too
tough to draw a line from A to B.

So... in the spirit of drawing pictures from your previous posts...
switches are the work of Satan... all audio equipment should be hardwired,
with silver wire and silver solder from the beginning to the end of each
and every chain so as not to be degraded by the horrific effects of
connectors, switches, transformers... or [gasp] a 'singing power
transformer'... while we're here... it should be duly noted that all
capacitors [with the exception of power supply filter caps] are inherently
evil beings that lead directly to marginal pop records... or did I go too
far?
--
Fletcher
Mercenary Audio
TEL: 508-543-0069
FAX: 508-543-9670
http://www.mercenary.com
"this is not a problem"

[Arny Krueger]

"Mike Rivers" > wrote in message
news:znr1057625329k@trad...
>
> In article > writes:
>
> > One thing I've discovered that's kind of interesting is that I can tell
> > when a device has a bad transformer just by putting a finger on the
> > chassis. It feels to me as though it's vibrating or trembling.

Just about anything with a power transformer is going to be pumping
measurable and perhaps audible vibration into the chassis. The major
operative phenomina are both normal magnetic attraction and repulsion, as
well as magnetostriction.

> Mechanical vibration of transformer windings can indeed be a source of
> acoustic noise. I suppose that it's possible to feel the vibration
> before you can hear it. But usually it's the power transformer that's
> got the loose windings or core laminations. Have you been able to
> isolate the "feel" of a signal transformer and feel it vibrate along
> with the audio?

Given that Boyk is into tubes, there's a likely explanation...

[Rick Knepper]

I keep seeing this thread and the model number and thinking Marshall
Amplification.

--
Rick Knepper
MicroComputer Support Services
Knepper Audio
Ft. Worth, TX
817-239-9632
413-215-1267 Fax
PC Tech Support & Equipment Sales
CDR Duplication & Audio Mastering
Recording
http://www.rknepper.com

[Ben Bradley]

In rec.audio.pro, James Boyk > wrote:

>One thing I've discovered that's kind of interesting is that I can tell
>when a device has a bad transformer just by putting a finger on the
>chassis. It feels to me as though it's vibrating or trembling. Other
>people don't seem to feel this.

I suspect you're talking about electrical leakage from a power
transformer (or power line RF filtering caps) in a piece of equipment
with an ungrounded chassis, and leaky power transformers causing a "60
or 70 volt" difference between different equipment. Your lack of
quoting Scott's previous message may have caused some confusion among
other posters...
I've experienced this with guitar amps with the 'line reverse'
switch, which capacitively couples one or the other side of the power
line to the chassis. The idea of the switch is to couple the neutral
side of the line to the chassis, reducing hum. When it's switched to
the 'hot' side, there's a lot more hum, and you can 'feel' the
'vibration' of the chassis with (one can only hope very
current-limited) AC voltage on it. Trying this is definitely NOT
RECOMMENDED, but if you do, do NOT do it barefoot, and do NOT touch
anything else while touching the chassis. The capacitor connected to
the 'line reverse' switch is supposed to limit the current to a 'safe'
value, but there's no guarantee that it's not shorted. Even if it's
okay, it's best not to have even a 'mild' current going through your
body. Looking back, I'm lucky to be alive, and I've heard of people
who aren't (because electric guitar amp safety wasn't the first thing
one learned about playing guitar, and amps didn't use
three-wire-with-ground power cords back then).
Didn't I recently post about this... Bill Whitlock wrote two
excellent articles on this, where ground currents come from and how
they get into the signal path: AN003 and AN004 at
http://www.jensen-transformers.com/ under "white papers."

>James Boyk

[James Boyk]

Ben Bradley wrote:
> I suspect you're talking about electrical leakage from a power
> transformer (or power line RF filtering caps) in a piece of equipment
> with an ungrounded chassis, and leaky power transformers causing a "60
> or 70 volt" difference between different equipment. Your lack of
> quoting Scott's previous message may have caused some confusion among
> other posters...

You are right. I did indeed mean that I can apparently feel the voltage
"absolutely," which is weird. Others don't feel anything.

I try to keep my posts to at most one screen total, but it tripped me up
this time. Sorry. My apologies.

James Boyk

[Ben Bradley]

In rec.audio.pro, James Boyk > wrote:

>Ben Bradley wrote:
>> I suspect you're talking about electrical leakage from a power
>> transformer (or power line RF filtering caps) in a piece of equipment
>> with an ungrounded chassis, and leaky power transformers causing a "60
>> or 70 volt" difference between different equipment. Your lack of
>> quoting Scott's previous message may have caused some confusion among
>> other posters...
>
>You are right. I did indeed mean that I can apparently feel the voltage
>"absolutely," which is weird. Others don't feel anything.

It's the body capacitance. The human body, standing in insulating
shoes, is effectively (if what I recall from another group is correct)
about 100pF to ground. Put about 50V of 60Hz through a 100pF to
ground, and [doing the calculations] a couple of microamps goes
through it, perhaps barely enough to be felt. I recall that such a
small 'vibrating' current is easier to feel if you lightly rub your
finger across the chassis rather than just press your finger against
it.
Maybe others were wearing shoes with thicker soles (were they going
out for disco dancing?), perhaps giving them less capacitance to
ground and less current flowing.

>I try to keep my posts to at most one screen total, but it tripped me up
>this time. Sorry. My apologies.
>
>James Boyk
>

[Justin Ulysses Morse]

In article >, James Boyk
> wrote:

> Mike Rivers wrote: > ...more microphones ...sound better when loaded
> with a transformer than when loaded with a capacitor and a few diode
> junctions.
>
> Good reason to use tubes.

You mean because then you'd HAVE to use a transformer? Or do you mean
because a WHOLE LOT of input capacitance would be preferable to just a
little?

ulysses

[James Boyk]

Justin Ulysses Morse wrote:
> ...However, it's important to consider that "live
> unadulterated" music derives a considerable degree of its Power and
> Delicacy from "non-auditory" cues.

If you close your eyes when listening to live music, and if you're in a
good hall, the power & delicacy will remain. Of course there are few
good halls--in LA, I knew only one apart from (I hope) the new Disney Hall.

James Boyk

[James Boyk]

Justin Ulysses Morse wrote:
> You mean like the Aromat/NAIS sealed PC-mount gold contact relays from
> Digikey. They're good enough for Great River and they're good enough
> for me. They're good.

I don't know them, but have you yourself listened to them against
hard-wired connections?

James Boyk

[Justin Ulysses Morse]

James Boyk > wrote:

> Justin Ulysses Morse wrote:
> > ...However, it's important to consider that "live
> > unadulterated" music derives a considerable degree of its Power and
> > Delicacy from "non-auditory" cues.
>
> If you close your eyes when listening to live music, and if you're in a
> good hall, the power & delicacy will remain. Of course there are few
> good halls--in LA, I knew only one apart from (I hope) the new Disney Hall.

In my experience, if you close your eyes while listening to live music,
you bump into somebody and get beer spilled on you, or you get your
knapsack stolen, or you miss out on Keith Patterson stripping down to
his skinny white skin and leopard-print undies and running around the
audience dry-humping a stuffed snake. There's no microphone in the
world that can capture this kind of magic. That's what flangers were
invented to replace. Of course if you DO see all that, you might be
distracted from the power and the delicacy transpiring elsewhere on the
stage.

One person's judgements don't apply to another person's experiences.

ulysses

[Justin Ulysses Morse]

James Boyk > wrote:

> Why do you think a transformer is necessary with tubes? My preamp
> doesn't use them. And why does input capacitance matter when coming from
> mike impedance through shortish cables? You do *assume* things!

I guess we both do, don't we? You assume that everybody's goal is to
make a recording that's exactly the same as what happened in the
studio. I find a lot of things that happen in the studio are less than
magical, and I don't let that stop me from making magical albums.

I assume that somebody who's concerned with purity as much as you are
would take steps to optimize noise performance of a microphone
preamplifier by feeding a gain stage with something close to its ideal
source impedance. Plugging a low-impedance microphone into a tube
stage with essentially infinite impedance is less than ideal from a
noise perspective, and simultaneously throws away all the free gain you
get from a transformer. I'm not one to throw away 30 or 40 dB of
dynamic range just because cheap transformers color the audio. More
often than not, I LIKE that coloration (because I pick good
transformers) and I've got other, more enjoyable noise sources to meet
my needs on that end.

ulysses

[James Boyk]

Justin Ulysses Morse wrote:
> I guess we both do, don't we? You assume that everybody's goal is to
> make a recording that's exactly the same as what happened in the
> studio.

I never record in a studio.


> I assume that somebody who's concerned with purity as much as you are
> would take steps to optimize noise performance of a microphone
> preamplifier by feeding a gain stage with something close to its ideal
> source impedance. Plugging a low-impedance microphone into a tube
> stage with essentially infinite impedance is less than ideal from a
> noise perspective, and simultaneously throws away all the free gain you
> get from a transformer.

What is this "free gain"? Noise gets stepped up along with the signal.

Minimizing noise may not be the right choice, if it forces
less-than-optimal sound quality. If a tube preamp without transformers
can record solo classical guitars with ribbons from six feet quietly
enough, and if those preamps sound superb because of having no
transformers, I think the tradeoff they embody makes sense, even though
they may not be the quietest possible.

James Boyk

[Mike Rivers]

In article > writes:

> > Good reason to use tubes.
>
> You mean because then you'd HAVE to use a transformer?

Yes.

> Or do you mean
> because a WHOLE LOT of input capacitance would be preferable to just a
> little?

I never thought of it that way, but it doesn't make as much sense as
using a transformer.


--
I'm really Mike Rivers - )

[ThePaulThomas]

The topic was the power & delicacy of live music.

And to think that some poor ******* started this thread thinking it
was actually about the Forssell JMP-1 mic preamp. ;)

[Frederick]

> And to think that some poor ******* started this thread thinking it
> was actually about the Forssell JMP-1 mic preamp. ;)

I'll survive... :)


Cheers
Frederick



--
Serwis Usenet w portalu Gazeta.pl -> http://www.gazeta.pl/usenet/

[Justin Ulysses Morse]

James Boyk > wrote:

> You're aware, I assume, that you've completely changed the topic. It's
> easy to make any point you wish to make if you do that. The topic was
> the power & delicacy of live music. Now it's become the non-acoustic
> happenings at a concert.


Actually, the topic was coloration in microphone preamps and why it can
be a good thing rather than something to be avoided at all costs.

ulysses

[Justin Ulysses Morse]

James Boyk > wrote:

> I never record in a studio.

Perspective, or lack thereof, shapes our outlook on this, doesn't it?

> What is this "free gain"? Noise gets stepped up along with the signal.

Room and microphone noise, yes. But amplifier noise is not stepped up
by the input transformer, is it?

> Minimizing noise may not be the right choice, if it forces
> less-than-optimal sound quality. If a tube preamp without transformers
> can record solo classical guitars with ribbons from six feet quietly
> enough, and if those preamps sound superb because of having no
> transformers, I think the tradeoff they embody makes sense, even though
> they may not be the quietest possible.

I completely agree with you there. If such a preamp exists, I'd
certainly like to hear it.

ulysses