this seems like a pretty good article on upgrading caps and resistors in
audio equipment, but I am not sure how far one wants to go in a SW receiver
!

http://www.bext.com/replace.htm

mike maghakian wrote:

this seems like a pretty good article on upgrading caps and resistors
in
audio equipment, but I am not sure how far one wants to go in a SW
receiver
!

http://www.bext.com/replace.htm
--------------------------------
Based on what Ihave been finding out in the last month pretty
much correct. I hope this line is a typo:
"For low voltage work, the 50V ECQ-P series from Panasonic
(available through Digi-Key) is excellent, but they only go up to
0.47pF" 0.47pF?? I hope that is 0.47uF.

Eletroclytics sound bad.
They sound wose when improperly biased.
I could hear no significant difference between the normal
unipolar one and the bi-polar units. At the very least shunt
them with 1uF polys.

And metalfilm resistors can be much quiter. I would love to
have the time, and money, to change all th carbon films in
one of my R2000s and compare the result to the other.

Worthwhile for SW? Clearly to some degree. I have found
the distortion caused by junky caps to be very significant.
The typical diode detector is clearly the worst, followed by
the alltoo common **** poor power IC. But caps can cause
the loss of of diffrence between "cofee" and "copy". In
inguistic terms it blurs the "frictive" and "plosive" sounds.
"Terry" and "Jerry" are other examples. Fro a clean, clear
and "strong" signal the diffrence is minimul. But for very weak,
sub S1 or with QRN/QRM it can make the difference beween
undersanding and just telling a voice is there. For non
native language, IE for me Spanish, I had noticed that I
required a much better signal to understand then with
English.

Grabbing the audio before it is so mungled, for the R2000
the Rec out is a good choice, using a good audio amp,
a small tub or MOSFET may be ideal, and using good
speakers or earphones can help. I decided that it was
well worth the considerable effort to use a better detector.
And seperate audio chain.

Distortion is just noise and degrades the audio in strange
and maybe unpredicatable ways. In my outboard ID strip,
synch and product detector, I am using metal film resistors
for all signal pathways. Overkilll? I don't know. A month ago
I would have, and did, scoff at the idea that the "fairly minor"
distrotions and colarations causd by caps power ICs and
diode detector could have ANY real effect. After all by the time
a radio wave makes it to my reciver from around the world,
with multiple hopes through a nasty ionosphere that in itself
does a good job at bluring audio, what is a little more here
going to hurt? Sadly a lot. I now have a higher "fi" post radio
audio chain then our main entertainment system. Of course
when listen to CSN&Y I am not dealing with weak signals
at the lower limits of "listenability".

Terry

wrote:
mike maghakian wrote:

this seems like a pretty good article on upgrading caps and resistors
in
audio equipment, but I am not sure how far one wants to go in a SW
receiver
!

http://www.bext.com/replace.htm
--------------------------------
Based on what Ihave been finding out in the last month pretty
much correct. I hope this line is a typo:
"For low voltage work, the 50V ECQ-P series from Panasonic
(available through Digi-Key) is excellent, but they only go up to
0.47pF" 0.47pF?? I hope that is 0.47uF.

Eletroclytics sound bad.
They sound wose when improperly biased.
I could hear no significant difference between the normal
unipolar one and the bi-polar units. At the very least shunt
them with 1uF polys.

And metalfilm resistors can be much quiter. I would love to
have the time, and money, to change all th carbon films in
one of my R2000s and compare the result to the other.

Worthwhile for SW? Clearly to some degree. I have found
the distortion caused by junky caps to be very significant.
The typical diode detector is clearly the worst, followed by
the alltoo common **** poor power IC. But caps can cause
the loss of of diffrence between "cofee" and "copy". In
inguistic terms it blurs the "frictive" and "plosive" sounds.
"Terry" and "Jerry" are other examples. Fro a clean, clear
and "strong" signal the diffrence is minimul. But for very weak,
sub S1 or with QRN/QRM it can make the difference beween
undersanding and just telling a voice is there. For non
native language, IE for me Spanish, I had noticed that I
required a much better signal to understand then with
English.

Grabbing the audio before it is so mungled, for the R2000
the Rec out is a good choice, using a good audio amp,
a small tub or MOSFET may be ideal, and using good
speakers or earphones can help. I decided that it was
well worth the considerable effort to use a better detector.
And seperate audio chain.

Distortion is just noise and degrades the audio in strange
and maybe unpredicatable ways. In my outboard ID strip,
synch and product detector, I am using metal film resistors
for all signal pathways. Overkilll? I don't know. A month ago
I would have, and did, scoff at the idea that the "fairly minor"
distrotions and colarations causd by caps power ICs and
diode detector could have ANY real effect. After all by the time
a radio wave makes it to my reciver from around the world,
with multiple hopes through a nasty ionosphere that in itself
does a good job at bluring audio, what is a little more here
going to hurt? Sadly a lot. I now have a higher "fi" post radio
audio chain then our main entertainment system. Of course
when listen to CSN&Y I am not dealing with weak signals
at the lower limits of "listenability".

Terry

An excellent post Terry, solid information on an interesting subject.
Well done.

bill
KC9CS

B. Otten wrote:

An excellent post Terry, solid information on an interesting subject.
Well done.

bill
KC9CS
-------------------------
Thanks, I realised after rereading my posts that it sounds
like I am "down" on bipolar audio amplifiers. I want to make
it clear that, in my opinion, bipolar amps can sound as good
(ie low distortion, clarity etc) as the best tube/valve amp. But
is is much easier to be great amps with tubes or MOSETs.

I had intended to build one of the audio amps at:
http://sound.westhost.com/projects-1.htm
His designs are well thought out and work very well.
The Pioneer MOSFET amps were an accident and reduced
my time and expense.

As I experiment more with this I become more convinced
that much of the superiority of great radios like Drake,
NRD, AOR, has as much to do with their choice of detector
as with the PLL/mixers. I have no doubt that their superior front
end and mixer help a lot, but even a middle of the road receiver
like the R2000 benifit greatly from even simple, less then the
insane lengths I am going through, modes.

The most bang for the buck would be to build a good precission
detector and couple it to a good, low distortion, amplifier.
This could all be built inside of a receiver like the R2000 which
would allow the decent internal speaker to be used

Even a mediocre receiver like the DX398 is a whole new animal
with an outboard active detector and better audio amp, and using
synch detection open new doors. I wish I had the skill to bild SMD
micro projects because Ithink there is money to be made offering
a simple add on synch detector, audio amp. I am being forced to
build a simpler outboard detector for my wife's DX398. I am going
to try and multiplex the IF on to the audio record out 3.5mm connector.

Terry