I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar to
the Eico ST-70.

I'm not a big fan of tone controls. I also wanted to try a really cool
remote volume control kit designed & sold by Mikkel Simonsen (unfortunately,
he doesn't hang around R.A.T. these days).

Mikkel's kit includes a time-delayed mute and power-on (e.g. B+) function on
a small PCB that runs off of the filament supply. Best thing about it is
that I can turn my amp on and off across the room from my lazy ass using the
remote (e.g. when the phone rings).

I removed the PECs and other tone control stuff from the Eico. I fashioned a
rack-mountable faceplate, painted with lettering.

I didn't use the ALPs control from Mikkel's kit (it was a bit big for this
app) but instead removed a 50K pot from a broken SS amplifier.

My design goals:

1) Present a reasonable impedance (200K) to the phono output and other
inputs;

2) Isolate the balance from the volume as best as possible;

3) Provide a buffered output for Tape or Line out

4) Mute the circuit on command by forcing the input to the main amplifier
stage to ground; do it in such a way as to avoid a click when changing
states.

The original tone circuit used the 2nd stage (12AU7 like) of a 7247 / 12DW7
in a CF configuration. I wanted to sub a 6CG7 for improved linearity. The
original 7247 CF was set to idle at 4 ma. I kept the same component values
for the 6CG7, although its specs are a little different.

Before I implement it, I had a few questions:

A) Is a 200K balance pot too low a value?

B) Any problems with the position of the mute switch in the circuit?

C) Any problem with the tap-off point for the Tape Out?

D) Any other apparent problems?

Thanks to anyone who cares to respond with advice.

Jon

Jon Yaeger wrote:
I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar to
the Eico ST-70.

I'm not a big fan of tone controls. I also wanted to try a really cool
remote volume control kit designed & sold by Mikkel Simonsen (unfortunately,
he doesn't hang around R.A.T. these days).

Mikkel's kit includes a time-delayed mute and power-on (e.g. B+) function on
a small PCB that runs off of the filament supply. Best thing about it is
that I can turn my amp on and off across the room from my lazy ass using the
remote (e.g. when the phone rings).

I removed the PECs and other tone control stuff from the Eico. I fashioned a
rack-mountable faceplate, painted with lettering.

How many old tube amps do you bugger in any given calendar year? And
are people gullible enough to pay more than scrap price when you are
done, or do you just have a pile of them building up in your garage??

Bret Ludwig wrote:

Jon Yaeger wrote:
I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar to
the Eico ST-70.

I'm not a big fan of tone controls. I also wanted to try a really cool
remote volume control kit designed & sold by Mikkel Simonsen (unfortunately,
he doesn't hang around R.A.T. these days).

Mikkel's kit includes a time-delayed mute and power-on (e.g. B+) function on
a small PCB that runs off of the filament supply. Best thing about it is
that I can turn my amp on and off across the room from my lazy ass using the
remote (e.g. when the phone rings).

I removed the PECs and other tone control stuff from the Eico. I fashioned a
rack-mountable faceplate, painted with lettering.

How many old tube amps do you bugger in any given calendar year? And
are people gullible enough to pay more than scrap price when you are
done, or do you just have a pile of them building up in your garage??

And how many times have you fell on your ass since you were a kid? Sounds like you
are good at it still. Bret, what a wuss you are!!!!!!!

Yeh, Its John Stewart

.... and in this corner ...

"Bret Ludwig" wrote in message
oups.com...

Jon Yaeger wrote:
I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar
to
the Eico ST-70.

I'm not a big fan of tone controls. I also wanted to try a really cool
remote volume control kit designed & sold by Mikkel Simonsen
(unfortunately,
he doesn't hang around R.A.T. these days).

Mikkel's kit includes a time-delayed mute and power-on (e.g. B+)
function on
a small PCB that runs off of the filament supply. Best thing about it
is
that I can turn my amp on and off across the room from my lazy ass using
the
remote (e.g. when the phone rings).

I removed the PECs and other tone control stuff from the Eico. I
fashioned a
rack-mountable faceplate, painted with lettering.

How many old tube amps do you bugger in any given calendar year? And
are people gullible enough to pay more than scrap price when you are
done, or do you just have a pile of them building up in your garage??

in article , Bret
Ludwig at wrote on 12/26/05 6:49 PM:


Jon Yaeger wrote:
I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar to
the Eico ST-70.

I'm not a big fan of tone controls. I also wanted to try a really cool
remote volume control kit designed & sold by Mikkel Simonsen (unfortunately,
he doesn't hang around R.A.T. these days).

Mikkel's kit includes a time-delayed mute and power-on (e.g. B+) function on
a small PCB that runs off of the filament supply. Best thing about it is
that I can turn my amp on and off across the room from my lazy ass using the
remote (e.g. when the phone rings).

I removed the PECs and other tone control stuff from the Eico. I fashioned a
rack-mountable faceplate, painted with lettering.

How many old tube amps do you bugger in any given calendar year?
And
are people gullible enough to pay more than scrap price when you are
done, or do you just have a pile of them building up in your garage??



Since you did such a yeoman's job of answering my questions, Bret, I've
taken the trouble to answer yours on a.b.s.e.

Jon

How many old tube amps do you bugger in any given calendar year? And
are people gullible enough to pay more than scrap price when you are
done, or do you just have a pile of them building up in your garage??

Those who know, do.
Those who do not know, carp.

Bret, you get closer and closer to joining the "big three idiots" here
with these sorts of posts. Comes to it, Phil, Andre and you would have
one helluva circle-jerk, and maybe would leave the rest of us alone.

I noted with some interest your post in RAR+P about a crystal detector
set (alone) capable of driving certain Klipsch speakers. That is not a
difficult trick to duplicate, depending on the diode you use for the
purpose. Some of the Galenium-Arsenide crystal & tickler devices you
can get even today will put out enough power through an appropriate
transformer to run a speaker if, as you say, you are close to a 50,000+
source. But what you will discover is that the audio bandwidth is about
2Hz, perhaps less. Enough for voice and a bit of instrument... maybe. I
have a little crystal (POK-ETTE Radio) set with a built-in speaker
(about 1") that does largely the same thing, but from a "modern"
germanium diode, so the output power is far less.

Everything you need to do this may be gotten he

http://www.xtalman.com/

Start with the Philmore Detector if you haven't the talent to roll your
own cat's whisker. It was the standard-of-the-industry back when.

Now, if you really want to do something rare and unusual.... OOPS... it
might take some actual work rather than carping on your part, try an FM
_CRYSTAL_ radio:

http://www.vmarsmanuals.co.uk/newsle...timeshobby.pdf


Peter Wieck
Wyncote, PA

In article .com,
" wrote:

Bret, you get closer and closer to joining the "big three idiots" here
with these sorts of posts. Comes to it, Phil, Andre and you would have
one helluva circle-jerk, and maybe would leave the rest of us alone.

I noted with some interest your post in RAR+P about a crystal detector
set (alone) capable of driving certain Klipsch speakers. That is not a
difficult trick to duplicate, depending on the diode you use for the
purpose. Some of the Galenium-Arsenide crystal & tickler devices you
can get even today will put out enough power through an appropriate
transformer to run a speaker if, as you say, you are close to a 50,000+
source. But what you will discover is that the audio bandwidth is about
2Hz, perhaps less. Enough for voice and a bit of instrument... maybe.

Why would the audio bandwidth be restricted to "2Hz"? I am assuming you
meant 2 kHz, not "2 Hz". The audio bandwidth can be anything you want, it
depends only on the loaded Q of the tuned circuits, which is not the same
thing as the coil Q. The J.W.Miller set mentioned in the original post
has a wide audio bandwidth.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

"John Byrns" wrote in message
...
In article .com,
" wrote:

for voice and a bit of instrument... maybe.

Why would the audio bandwidth be restricted to "2Hz"? I am assuming you
meant 2 kHz, not "2 Hz". The audio bandwidth can be anything you want, it
depends only on the loaded Q of the tuned circuits, which is not the same
thing as the coil Q. The J.W.Miller set mentioned in the original post
has a wide audio bandwidth.


Regards,

John Byrns




Loaded Q, and the frequency... (Arithmetic selectivity..)

Pete

Why would the audio bandwidth be restricted to "2Hz"

Sorry, miswrote. But to get the kind of power to drive a speaker per
the description, the audio bandwidth gets restricted to about 2KHz...
my mistake. At least in my *direct* experience.

Peter Wieck
Wyncote, PA

Jon Yaeger wrote:
I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar to
the Eico ST-70.

I removed the PECs and other tone control stuff from the Eico.

What is a PEC?

thanks...

in article ,
at wrote on 12/27/05 5:18 PM:

Jon Yaeger wrote:
I bought an Eico 2080 Integrated Amplifier on eBay. It is very similar to
the Eico ST-70.

I removed the PECs and other tone control stuff from the Eico.

What is a PEC?

thanks...



Printed Electronic Circuit - a precursor to modern ICs. Tended to drift all
over the place . . .

In article .com,
" wrote:

Why would the audio bandwidth be restricted to "2Hz"

Sorry, miswrote. But to get the kind of power to drive a speaker per
the description, the audio bandwidth gets restricted to about 2KHz...
my mistake. At least in my *direct* experience.

This doesn't make much sense, to get the kind of power required to drive a
speaker requires proper impedance matching, but the bandwidth is
independent of proper matching. Can you explain why proper matching
should require unusually narrow bandwidth? There is one reason I can
envision, which is a narrow band antenna system, which I suppose the
typical short wire antenna would qualify as.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

but the bandwidth is
independent of proper matching. Can you explain why proper matching
should require unusually narrow bandwidth? There is one reason I can
envision, which is a narrow band antenna system, which I suppose the
typical short wire antenna would qualify as.

John:

If you want an explanation in the engineering sense, I am not an
engineer... but let's see if this does the trick. A priori, I wish to
state that I am relating my direct experience with a crystal detector
driving a standard 4-ohm nominal relatively efficient audio speaker.
NOTE: I did not say "high fidelity". The speaker was a so-called
'full-range' concentric speaker designed for use in cars.

The basic explanation is that if the entire bandwidth is concentrated
into a very narrow range... without clamping the edges, more powers is
concentrated into the 'sweet spot'. Kinda like concentrating a given
flow of liquid into a narrow channel. If one needs to pass so many
gallons-per-minute, and the channel gets narrow, the speed of the flow
gets faster. (I do like plumbing analogies given the Brit "VALVE"
designation).

When the phenomenon was demonstrated to me, the choice was a specific
output transformer that -somehow- did exactly that. It was fed via an
R/C arrangement that the demonstrator could vary... as the signal
became more 'full range' the volume dropped... like a stone.

On the other hand, the antenna in question was about 50' of wire strung
over the pavilion joists (Kutztown Radio Swap some years ago), and
nothing otherwise special. I am not trying to be evasive, but at the
same time, I am reporting my direct observations of a home-brew crystal
set without any external amplification driving a single speaker at a
volume sufficient to be heard in the setting.

Peter Wieck
Wyncote, PA

On 27 Dec 2005 17:18:31 -0800, " wrote:

When the phenomenon was demonstrated to me, the choice was a specific
output transformer that -somehow- did exactly that. It was fed via an
R/C arrangement that the demonstrator could vary... as the signal
became more 'full range' the volume dropped... like a stone.

On the other hand, the antenna in question was about 50' of wire strung
over the pavilion joists (Kutztown Radio Swap some years ago), and
nothing otherwise special. I am not trying to be evasive, but at the
same time, I am reporting my direct observations of a home-brew crystal
set without any external amplification driving a single speaker at a
volume sufficient to be heard in the setting.

Let me suggest that the quantity y'all are discussing is
the classic "Q", and in its primeval state.

The name "Q', currently meaning the ratio of reactive to
resistive impedance, originated in this very topic. It
originally was very hard to come by, and the trade-off's
you've observed were an everyday issue for radio reception.

ps: the "Q" was originally short for "quality factor".
Sorry; historical sidelight; now back to your regularly
scheduled station,

Chris Hornbeck

On Tue, 27 Dec 2005 17:18:31 -0800, wrote:

but the bandwidth is
independent of proper matching. Can you explain why proper matching
should require unusually narrow bandwidth? There is one reason I can
envision, which is a narrow band antenna system, which I suppose the
typical short wire antenna would qualify as.

John:

If you want an explanation in the engineering sense, I am not an
engineer... but let's see if this does the trick. A priori, I wish to
state that I am relating my direct experience with a crystal detector
driving a standard 4-ohm nominal relatively efficient audio speaker.
NOTE: I did not say "high fidelity". The speaker was a so-called
'full-range' concentric speaker designed for use in cars.

The basic explanation is that if the entire bandwidth is concentrated
into a very narrow range... without clamping the edges, more powers is
concentrated into the 'sweet spot'. Kinda like concentrating a given
flow of liquid into a narrow channel. If one needs to pass so many
gallons-per-minute, and the channel gets narrow, the speed of the flow
gets faster. (I do like plumbing analogies given the Brit "VALVE"
designation).

When the phenomenon was demonstrated to me, the choice was a specific
output transformer that -somehow- did exactly that. It was fed via an
R/C arrangement that the demonstrator could vary... as the signal
became more 'full range' the volume dropped... like a stone.

On the other hand, the antenna in question was about 50' of wire strung
over the pavilion joists (Kutztown Radio Swap some years ago), and
nothing otherwise special. I am not trying to be evasive, but at the
same time, I am reporting my direct observations of a home-brew crystal
set without any external amplification driving a single speaker at a
volume sufficient to be heard in the setting.

Peter Wieck
Wyncote, PA


You need to know what the "R/C arrangement" was doing. Resistors
dissipate power and you certainly don't want any of them around when you
are trying something like this. You should even consider the resistance
of the output transformer.

As far as your water pipe analogy, if the station you wanted to listen to
was broadcasting white noise it might have some validity. However, most
people prefer music or speech, both of which have very little energy above
a few KHz. That is why records and FM radio use pre-emphasis; it boosts
the highs before transmission so they don't get lost in noise. At the
receiving end, they are cut back down to size reducing the noise at the
same time.

The Q of the tuned circuit used in the receiver has a direct effect on
bandwidth as well as efficiency. High Q gives narrower bandwidth and
higher efficiency (for the circuit by itself). Coupling a load to the
circuit reduces the Q no matter how good the circuit itself is. That is
why old receivers used "loose couplers"; the lower loading
increased the selectivity. Simultaneously, it also reduced the
loudness of the signal received; they were adjustable so the operator
could reach some sort of compromise. Since most crystal sets (even using
headphones) have trouble receiving less than half the broadcast band at
once, I sincerely doubt that they could get a high enough Q to limit the
bandwidth to anything like 2KHz, especially while driving a speaker.

--
Jim Mueller

To get my real email address, replace wrongname with eportiz.
Then replace nospam with sacbeemail.