A lucky find

I went to a rummage sale and the guy had a box of cables for 10 cents
each. Some computer power cords, and some RCA cables, and a couple phone
cords. 16 cords total. I offered $1 for the whole box, and he agreed.

He asked me why I needed all of them. I told him I work on electronics.
Thats when he said he has something I might want. He went in the house
and came out with a Kenwood Basic C2, Stereo Control Amplifier. Made in
(1984-90). The guy said it's dead, and he was going to throw it away, so
I can have it. He said he connected speakers to it and it dont do
anything.

I got home and was getting out a RCA plug to connect to the output
terminals, to hook up a speaker, when I began to look closer at it, and
thought "this is a preamp, not a power amp". To make sure what I had, I
looked on the web, and found this:
https://www.hifiengine.com/manual_library/kenwood/basic-c2.shtml

I have to admit, this is called an "amplifier" so I did sort of think it
needed speakers, even though RCA plugs are not usually used for speakers
except some of the real old cheap stuff.

It turned out this was my lucky day. This preamp sounds great. (And I
didn't even connect it to my main power amp yet, I just connected it to
a small mono guitar amp that I use for testing stuff in the shop. It
needed a little contact cleaner on the selector switches, but works
great.

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my cartridge
is MM or MC, and what the resistance rating is?

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

 

[Dave M]

oldschool@tubes.com wrote:

It turned out this was my lucky day. This preamp sounds great. (And I
didn't even connect it to my main power amp yet, I just connected it
to a small mono guitar amp that I use for testing stuff in the shop.
It needed a little contact cleaner on the selector switches, but works
great.

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my
cartridge is MM or MC, and what the resistance rating is?

This appears to be a real useful thing, but I never even knew there
were different kinds of cartridges. In the past, I just installed a
cartridge and plugged it into "Phono".

Take a look at the description at
http://www.needledoctor.com/core/media/media.nl?id=2701&c=ACCT106601&h=192e59a68f2e49fdd1f8&_xt=.html.
That should get you going on the differences and why you would choose one
over the other. Basically, it's a choice based on your listening habits and
the type of sound you want from your system.

Dave M

 

[Ralph Mowery]

In article <ge0rhc1u4ivka1711na2ap84mjn8ratkbd@4ax.com>,
oldschool@tubes.com says...

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my cartridge
is MM or MC, and what the resistance rating is?

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

It would seem to me you could just use an ohm meter on the cartridge and
see what the resistance is. If very low it would be the mc and if say
10K or greater it would be the MM.

 

[pfjw@aol.com]

On Thursday, May 18, 2017 at 9:59:31 AM UTC-4, Ralph Mowery wrote:

It would seem to me you could just use an ohm meter on the cartridge and
see what the resistance is. If very low it would be the mc and if say
10K or greater it would be the MM.

Ummmmm..........

Be EXCEEDINGLY careful in putting a VOM across any phono cartridge, most especially an MC cartridge. Some (cheap) VOMS will put as much as 9V through the coils - not a good thing. And batteries will deliver current to their chemical limits - thinner-than-human-hair wire does not like heat.

Peter Wieck
Melrose Park, PA

 

[pfjw@aol.com]

On Thursday, May 18, 2017 at 9:15:09 AM UTC-4, olds...@tubes.com wrote:

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

You have an MM cartridge unless it has an outboard head-amp and/or transformer. Start at 100K. If it sound anemic, move to 47K.

Peter Wieck
Melrose Park, PA

 

[Michael Black]

On Thu, 18 May 2017, oldschool@tubes.com wrote:

I went to a rummage sale and the guy had a box of cables for 10 cents
each. Some computer power cords, and some RCA cables, and a couple phone
cords. 16 cords total. I offered $1 for the whole box, and he agreed.

He asked me why I needed all of them. I told him I work on electronics.
Thats when he said he has something I might want. He went in the house
and came out with a Kenwood Basic C2, Stereo Control Amplifier. Made in
(1984-90). The guy said it's dead, and he was going to throw it away, so
I can have it. He said he connected speakers to it and it dont do
anything.

I got home and was getting out a RCA plug to connect to the output
terminals, to hook up a speaker, when I began to look closer at it, and
thought "this is a preamp, not a power amp". To make sure what I had, I
looked on the web, and found this:
https://www.hifiengine.com/manual_library/kenwood/basic-c2.shtml

I have to admit, this is called an "amplifier" so I did sort of think it
needed speakers, even though RCA plugs are not usually used for speakers
except some of the real old cheap stuff.

It turned out this was my lucky day. This preamp sounds great. (And I
didn't even connect it to my main power amp yet, I just connected it to
a small mono guitar amp that I use for testing stuff in the shop. It
needed a little contact cleaner on the selector switches, but works
great.

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my cartridge
is MM or MC, and what the resistance rating is?

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

Most cartridges (unless it's a really cheap turntable in which case it's a
crystal or ceramic cartridge) are moving magnet. At least that used to be
the case, the moving magnet coil ones were the exception for the ones who
wanted to spend more, and you'd need an extra preamp for it.

Maybe that's changed, with fewer people owning turntables, maybe the ones
using them tend to use moving coil cartridges.

But the default is moving magnet.

Michael

 

[Ralph Mowery]

In article <9dc02317-2ec5-4558-b585-02b29cb51a14@googlegroups.com>,
pfjw@aol.com says...

On Thursday, May 18, 2017 at 9:59:31 AM UTC-4, Ralph Mowery wrote:

It would seem to me you could just use an ohm meter on the cartridge and
see what the resistance is. If very low it would be the mc and if say
10K or greater it would be the MM.

Ummmmm..........

Be EXCEEDINGLY careful in putting a VOM across any phono cartridge, most especially an MC cartridge. Some (cheap) VOMS will put as much as 9V through the coils - not a good thing. And batteries will deliver current to their chemical limits - thinner-than-human-hair wire does not like heat.

Maybe with the older anlaog meters. I so seldom drage out the analog
meter for ohms I was not thinking about that one.

The newer digital meters only let a very small ammount of current flow
in the ohms position. I mesured a cheep HF $ 5 (free with coupon)
meter at less than 2 ma, and a Fluke 87 with less than .5 ma on the low
ohm scales.

My good old Sompson 260 will put out just under 100 ma on the low ohms
scale.

 

On Thursday, 18 May 2017 14:15:09 UTC+1, olds...@tubes.com wrote:

I went to a rummage sale and the guy had a box of cables for 10 cents
each. Some computer power cords, and some RCA cables, and a couple phone
cords. 16 cords total. I offered $1 for the whole box, and he agreed.

He asked me why I needed all of them. I told him I work on electronics.
Thats when he said he has something I might want. He went in the house
and came out with a Kenwood Basic C2, Stereo Control Amplifier. Made in
(1984-90). The guy said it's dead, and he was going to throw it away, so
I can have it. He said he connected speakers to it and it dont do
anything.

I got home and was getting out a RCA plug to connect to the output
terminals, to hook up a speaker, when I began to look closer at it, and
thought "this is a preamp, not a power amp". To make sure what I had, I
looked on the web, and found this:
https://www.hifiengine.com/manual_library/kenwood/basic-c2.shtml

I have to admit, this is called an "amplifier" so I did sort of think it
needed speakers, even though RCA plugs are not usually used for speakers
except some of the real old cheap stuff.

It turned out this was my lucky day. This preamp sounds great. (And I
didn't even connect it to my main power amp yet, I just connected it to
a small mono guitar amp that I use for testing stuff in the shop. It
needed a little contact cleaner on the selector switches, but works
great.

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my cartridge
is MM or MC, and what the resistance rating is?

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

99.99% of hifi phono carts are MM 47k. You can try the 100k setting without harm, but that may not be true of the MC setting, which expects far lower input.


NT

 

On Thu, 18 May 2017 10:56:05 -0400, Michael Black <et472@ncf.ca> wrote:

On Thu, 18 May 2017, oldschool@tubes.com wrote:

I went to a rummage sale and the guy had a box of cables for 10 cents
each. Some computer power cords, and some RCA cables, and a couple phone
cords. 16 cords total. I offered $1 for the whole box, and he agreed.

He asked me why I needed all of them. I told him I work on electronics.
Thats when he said he has something I might want. He went in the house
and came out with a Kenwood Basic C2, Stereo Control Amplifier. Made in
(1984-90). The guy said it's dead, and he was going to throw it away, so
I can have it. He said he connected speakers to it and it dont do
anything.

I got home and was getting out a RCA plug to connect to the output
terminals, to hook up a speaker, when I began to look closer at it, and
thought "this is a preamp, not a power amp". To make sure what I had, I
looked on the web, and found this:
https://www.hifiengine.com/manual_library/kenwood/basic-c2.shtml

I have to admit, this is called an "amplifier" so I did sort of think it
needed speakers, even though RCA plugs are not usually used for speakers
except some of the real old cheap stuff.

It turned out this was my lucky day. This preamp sounds great. (And I
didn't even connect it to my main power amp yet, I just connected it to
a small mono guitar amp that I use for testing stuff in the shop. It
needed a little contact cleaner on the selector switches, but works
great.

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my cartridge
is MM or MC, and what the resistance rating is?

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

Most cartridges (unless it's a really cheap turntable in which case it's a
crystal or ceramic cartridge) are moving magnet. At least that used to be
the case, the moving magnet coil ones were the exception for the ones who
wanted to spend more, and you'd need an extra preamp for it.

Maybe that's changed, with fewer people owning turntables, maybe the ones
using them tend to use moving coil cartridges.

But the default is moving magnet.

Michael

Good article on that website listed. I have two turntables. The cheap
one has a non-removable (as far as I know) cartridge. I dont have a
cartridge number, but its an AIWA turntable, and takes an AN-11 stylus.
The good turntable has an Audio Technica AT5011E. I also have a spare
cartridge from way back, (new in the box), Electro Voice V100.

I'm pretty sure the Audio Technica and the Electro Voice are both MM.
Probably the AIWA one too, unless thats a crystal or ceramic.

I imagine there is a place to look them up, but I have not yet tried to
find a website that lists them.

As far as using an ohm meter. I do understand the old analog ones are
probably not a good idea. I do have a modern digital one (not one of
those cheap HF ones). But what about using a VTVM. I may be wrong, but
it's my understanding that VTVMs are safe to use on darn near anything.
I have two of them, a Heathkit and an Eico.

(Presently the Heathkit one tends to act a bit flakey, probably needs
new caps, but the Eico works fine).

But it's probably easier to just look them up by model.

Not to mention..... Both the AT and the EV have FOUR wires coming from
them, but when they exit the turntable, they only have TWO (as in RCA
plugs). What are the other two wires for?????

 

[pfjw@aol.com]

On Thursday, May 18, 2017 at 2:18:08 PM UTC-4, olds...@tubes.com wrote:

As far as using an ohm meter. I do understand the old analog ones are
probably not a good idea. I do have a modern digital one (not one of
those cheap HF ones). But what about using a VTVM. I may be wrong, but
it's my understanding that VTVMs are safe to use on darn near anything.
I have two of them, a Heathkit and an Eico.

Whoooo Boy! I can think of no reason whatsoever that one should ever use a VTVM in these modern times. Sure, loading a Zenith TransOceanic while performing an alignment via a VTVM makes some of the things go 'by the book', but using a regular high-quality VOM is just fine. Better in many cases. Nor would I ever advocate using a mains-connected VTVM on much audio stuff in any case. Nor do I appreciate them as ancient tools. I do not have enough real-estate on my bench to entertain tools that are not useful.

(Presently the Heathkit one tends to act a bit flakey, probably needs
new caps, but the Eico works fine).

But it's probably easier to just look them up by model.

Wheeee.....

A typical stereo phono cartridge of any ilk has four (4) wires coming out of it. Some (very) cheap devices have only three, sharing the ground between the channels, but I have not seen one of those for over 30 years.

Not to mention..... Both the AT and the EV have FOUR wires coming from
them, but when they exit the turntable, they only have TWO (as in RCA
plugs). What are the other two wires for?????

So, we have:

SR/RG (signal right/right ground)
SL/LG (signal left/Left ground)

Which goes to Right RCA Jack as follows:

SR to center post. RG to shell (shield).

And the left RCA Jack as follows:

SL to the center post. LG to the shell (shield).

Magically, four wires go to two wires.

There should be a general ground wire in there somewhere - which *SHOULD NOT* go to the pre-amp/amp chassis ground but to either of the shells on either of the jacks.

Peter Wieck
Melrose Park, PA

One cannot make this stuff up!

On some great and glorious day the plain folks of the land will reach their heart's desire at last, and the White House will be adorned by a downright moron.

H.L. Mencken

 

On Thursday, May 18, 2017 at 3:02:12 PM UTC-4, pf...@aol.com wrote:

On some great and glorious day the plain folks of the land will reach their heart's desire at last, and the White House will be adorned by a downright moron.

H.L. Mencken

A true prophet.. Two in a row; a *long* 16 years (and one a socialist). Hopefully the next 8 years will be better.

 

[Foxs Mercantile]

On 5/18/2017 2:38 PM, ohger1s@gmail.com wrote:
> Hopefully the next 8 years will be better.

It's just like watching The Lord of the Flies now.



--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

---
This email has been checked for viruses by AVG.
http://www.avg.com

 

[Ralph Mowery]

In article <d5krhctif1agoutg0c47nhomo071l5vv01@4ax.com>,
oldschool@tubes.com says...

As far as using an ohm meter. I do understand the old analog ones are
probably not a good idea. I do have a modern digital one (not one of
those cheap HF ones). But what about using a VTVM. I may be wrong, but
it's my understanding that VTVMs are safe to use on darn near anything.
I have two of them, a Heathkit and an Eico.

(Presently the Heathkit one tends to act a bit flakey, probably needs
new caps, but the Eico works fine).

I have a Heathkit VTVM I put together over 40 years ago. I had it out a
while back just to see if it still worked. It was slightly flakey and I
gave it a shot of the Deoxit on the switches and that made it work like
it did when I built it.

I don't know what kind of current it puts out in the ohms position. I
doubt I will ever use it for anything but maybe where I need a zero
center scale meter.

 

On Thursday, 18 May 2017 19:18:08 UTC+1, olds...@tubes.com wrote:

On Thu, 18 May 2017 10:56:05 -0400, Michael Black <et472@ncf.ca> wrote:
On Thu, 18 May 2017, oldschool@tubes.com wrote:

Good article on that website listed. I have two turntables. The cheap
one has a non-removable (as far as I know) cartridge. I dont have a
cartridge number, but its an AIWA turntable, and takes an AN-11 stylus.
The good turntable has an Audio Technica AT5011E. I also have a spare
cartridge from way back, (new in the box), Electro Voice V100.

I'm pretty sure the Audio Technica and the Electro Voice are both MM.
Probably the AIWA one too, unless thats a crystal or ceramic.

I imagine there is a place to look them up, but I have not yet tried to
find a website that lists them.

It's easy to tell magnetic from ceramic. Magnetic styli are in a squarish plastic piece that slides out - or rarely in the case of one of the AT unclips downward. Ceramic styli are unencased, and clip in. Old ones have a flipover sidearm to select from 2 needles, typically LP & 78.

The other way to tell them is to wobble the arm slightly when playing. Magnetics let the arm/needle wobble, ceramics don't.

As far as using an ohm meter. I do understand the old analog ones are
probably not a good idea. I do have a modern digital one (not one of
those cheap HF ones). But what about using a VTVM. I may be wrong, but
it's my understanding that VTVMs are safe to use on darn near anything.
I have two of them, a Heathkit and an Eico.

totally pointless.

Not to mention..... Both the AT and the EV have FOUR wires coming from
them, but when they exit the turntable, they only have TWO (as in RCA
plugs). What are the other two wires for?????

Each RCA plus has 2 conductors, outer and inner.


NT

 

[Dave Platt]

In article <ge0rhc1u4ivka1711na2ap84mjn8ratkbd@4ax.com>,
<oldschool@tubes.com> wrote:

Yes, you got a lucky find!

I've bought a very nice receiver (a Proton) where the seller said it
didn't work at all, and the reason was that he hadn't read the manual
and seen that the receiver needs a jumper between "preamp out" and
"amp in" if you aren't using an external signal processor. The
original jumpers had been lost at some point and the owner didn't do
his research...

I am a little confused though about the phone switch.
It has the following selections:

MM (Moving Magnet)
47K
100K

MC (Moving Coil)
10 ohm
30 ohm
100 ohm

Ok, I understand what they are saying, but how do I know if my cartridge
is MM or MC, and what the resistance rating is?

Ummm... search the Internet for its part number?

Or, measure its DC resistance with an ohmmeter. If it reads a few
ohms, it's certainly a moving-coil amplifier. If it reads hundreds,
it's probably a moving-magnet (there are some higher-impedance moving
coil cartridges but they're less common).

The numbers you see above are not those of the cartridges... they're
the parallel resistance of the phono stage itself, in that setting.
The frequency response of any phono cartridge will depend to some
extent on the load resistance. The cartridge maker may specify the
recommended load.

This appears to be a real useful thing, but I never even knew there were
different kinds of cartridges. In the past, I just installed a cartridge
and plugged it into "Phono".

Cartridges that you can do that with, are almost all moving-magnet (or
moving-iron) cartridges. The MM setting, and 47k ohms input
impedance, would very probably be the one to choose - that's the
industry-standard resistance.

MC cartridges typically have a significantly lower output
voltage... plugging them into an MM input will result in very low
audio levels. One needs a bunch of additional voltage gain (provided
by the preamp in MC mode, by an external "head amp", or by a signal
transformer) to use a low-output MC cartridge.

 

[rickman]

On 5/18/2017 3:02 PM, pfjw@aol.com wrote:

On Thursday, May 18, 2017 at 2:18:08 PM UTC-4, olds...@tubes.com wrote:

As far as using an ohm meter. I do understand the old analog ones are
probably not a good idea. I do have a modern digital one (not one of
those cheap HF ones). But what about using a VTVM. I may be wrong, but
it's my understanding that VTVMs are safe to use on darn near anything.
I have two of them, a Heathkit and an Eico.

Whoooo Boy! I can think of no reason whatsoever that one should ever use a VTVM in these modern times. Sure, loading a Zenith TransOceanic while performing an alignment via a VTVM makes some of the things go 'by the book', but using a regular high-quality VOM is just fine. Better in many cases. Nor would I ever advocate using a mains-connected VTVM on much audio stuff in any case. Nor do I appreciate them as ancient tools. I do not have enough real-estate on my bench to entertain tools that are not useful.

You are addressing someone who *just* discovered nanofarads. Consider
his state of mind.

--

Rick C

 

[Foxs Mercantile]

On 5/18/2017 7:18 PM, rickman wrote:

You are addressing someone who *just* discovered nanofarads.
Consider his state of mind.

That and RCA connectors actually have TWO connections.

--
Jeff-1.0
wa6fwi
http://www.foxsmercantile.com

---
This email has been checked for viruses by AVG.
http://www.avg.com

 

On Thu, 18 May 2017 14:25:42 -0700, dplatt@coop.radagast.org (Dave
Platt) wrote:

Yes, you got a lucky find!

I've bought a very nice receiver (a Proton) where the seller said it
didn't work at all, and the reason was that he hadn't read the manual
and seen that the receiver needs a jumper between "preamp out" and
"amp in" if you aren't using an external signal processor. The
original jumpers had been lost at some point and the owner didn't do
his research...

Sounds like you got a good deal too. I am very familiar with those
jumpers. My Altec Lansing commercial power amp has those.

The guy that gave me this preamp did a similar thing. He thought that
the RCA jacks marked "Output" were for speakers. That threw me off too,
because he had said that, but in a matter of minutes I realized this is
not a power amp. Looking it up online confirmed that.

About the only things that I recall using RCA plugs on speakers were
some of those really old portable record players from the 50s and 60s.
The speakers would unplug using a RCA jack/plug and the speakers lifted
off the record player, using special hinges with pins that stuck out, so
the speakers could be moved.

 

On Thu, 18 May 2017 16:58:43 -0400, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

In article <d5krhctif1agoutg0c47nhomo071l5vv01@4ax.com>,
oldschool@tubes.com says...

As far as using an ohm meter. I do understand the old analog ones are
probably not a good idea. I do have a modern digital one (not one of
those cheap HF ones). But what about using a VTVM. I may be wrong, but
it's my understanding that VTVMs are safe to use on darn near anything.
I have two of them, a Heathkit and an Eico.

(Presently the Heathkit one tends to act a bit flakey, probably needs
new caps, but the Eico works fine).



I have a Heathkit VTVM I put together over 40 years ago. I had it out a
while back just to see if it still worked. It was slightly flakey and I
gave it a shot of the Deoxit on the switches and that made it work like
it did when I built it.

I don't know what kind of current it puts out in the ohms position. I
doubt I will ever use it for anything but maybe where I need a zero
center scale meter.

That's something I should do with my Heathkit VTVM, use the Deoxit.
Maybe that is all it needs.... But I do plan to recap it anyhow. At
least the power supply lytics....

I use almost all old tube based test gear, but I normally only work on
tube stuff, so I use what matches the equipment.

Lately, I have been working on a lot of solid state stuff. I'd rather
work on tubes, but this soild state stuff is my own stuff, so I work on
it. I generally use all modern test gear on solid state equipment,
except for my old Paco tube signal tracer. That thing works on
everything and is probably my most used piece of test gear.

But I like that old tube test gear, for working on tube stuff. My
Sencore scope is solid state, but it's still quite old. I recently got
all five of the old Eico probes, plus the high voltage probe they sold.
So I am now equipped with probes for almost every need. Eico made the
best probes ever, and I really had a tough time getting all of them.
I'll probably never need the high voltage one, since I dont work on old
CRT tvs, but it came with the other probes.

All I need now, is an old 50s era panel truck so I can paint "Radio
Repair" on the sides!!!