Pace underdash 8 track player instalation instructions

I would like to install my Pace Underdash 8 track player in my 1989
Buick Lesabre. Can this be done with a harness and a splitter of some
kind so I can use the delco am/fm cassette indash unit as well as the
8 track. Would I need seperate speakers? Can this be done? I would be
grateful if someone could help me out.

Thanks
Rusty

On 29 May 2007 22:34:54 -0700, Rusty wrote:

I would like to install my Pace Underdash 8 track player in my 1989
Buick Lesabre. Can this be done with a harness and a splitter of some
kind so I can use the delco am/fm cassette indash unit as well as the
8 track. Would I need seperate speakers? Can this be done? I would be
grateful if someone could help me out.snip

It has its own (not-so-good) audio amps, so you cannot simply feed one
into the other. There ARE ways to use the first voltage stage of the
amplifiers to provide a line level output to go into an aux input of
another unit, but the stock Delco has no facility for that at all. I
did this with a combo CD/cassette/radio unit that had an audio input
for a CD changer, which is line level out, and it worked fabulously
until I got rid of the 8 track in that car. Reason: I dubbed all my
still-wanted 8 tracks onto CD-Rs, so why bother with a troublesome,
clunky 8 track that was always in the way?

You either use separate speakers, or you MAY be able to use an
underdash EQ/amplifier and route both the stock radio and the 8 track
into it. For good quality, though, you'll need to bypass the output
transistors in both units, which are a major source of distortion
whether they're driving speakers OR just providing voltage into a
resistive load.

Overall, the best feasibility for someone with no electronic skills is
to simply put in two more speakers (somewhere) and run the 8 track all
by itself.

Rusty wrote:
I would like to install my Pace Underdash 8 track player in my 1989
Buick Lesabre. Can this be done with a harness and a splitter of some
kind so I can use the delco am/fm cassette indash unit as well as the
8 track.

Like Bob said, the simplest thing to do (electrically) is to just
install two more speakers that are wired directly to the 8-track deck.
Mechanically it might be interesting to find a place to mount the
speakers, but you can probably do it.

If you don't want to install more speakers, a simple thing to do, albeit
probably with reduced sound quality, is to wire the outputs of the 8-
track deck to one of those "CD to cassette" adapters, or an FM modulator
as used with MP3 players. This would route the 8-track output to a
"cassette" that could be plugged into the Delco, or onto an FM frequency
that could be received on the Delco. This lets you use all four of the
stock speakers without much fancy wiring.

If you don't want to use the CD-cassette adapter or the FM modulator,
the next possibility is to install a couple of toggle switches so you
can select whether the front speakers are connected to the stock Delco
tuner or the 8-track. You used to be able to get a single switch that
would do this, but these days it's probably easier to use two switches.

In a nutshell, you'd need two DPDT switches. You'd take the Delco radio
out of the dash and identify the two wires in the harness that go to the
left front speaker. You'd cut those two wires and splice more wire onto
the four ends you have, and route the four longer wires to where you want
to mount the toggle switches. The wires coming from the speaker (harness
side) would go to the wiper of one of the toggle switches. The wires
coming from the Delco radio (connector side) would go to one end of that
toggle switch. You would then run the left speaker wires from the
8-track deck to the other end of that toggle switch. You would then
repeat the cut, splice, connect-to-switch for the right channel.

To operate, you'd start with the Delco and the 8-track both shut off.
To listen to the Delco, make sure both switches are flipped the right
way, and then turn on the Delco and listen to the radio or a cassette.
To switch to 8-track, turn off the Delco, flip both switches the other
way, then turn on the 8-track deck. To switch back to the Delco, shut
off the 8-track deck, flip both the switches, then turn the Delco back
on. The goal is to avoid having either the Delco or the 8-track turned
on and playing without any speakers connected. Both units _probably_
don't mind playing with no speakers connected, but there is a small
chance that one or both of them might be damaged.

If you didn't like the look of the two toggle switches, you could do
the same thing with four standard automotive relays and a single
push-on push-off switch. The wiring would look a mess, but the finished
product might look a little cleaner.

The main thing is that you have to have something else in the equation
besides the Delco, the 8-track, the speakers, and pieces of wire. If
you try to hook the Delco and the 8-track to the same speakers without
anything else in between, you _will_ damage the Delco or the 8-track or
both.

If none of the above stuff makes very much sense, then consider
installing more speakers for the 8-track.

Matt Roberds

On May 30, 1:34 am, Rusty wrote:
I would like to install my Pace Underdash 8 track player in my 1989
Buick Lesabre. Can this be done with a harness and a splitter of some
kind so I can use the delco am/fm cassette indash unit as well as the
8 track. Would I need seperate speakers? Can this be done? I would be
grateful if someone could help me out.

Thanks
Rusty



you can wire it to the same speakers, just make sure the delco it off
while playing the 8-track

and whatever you do, don't listen to DeserTBob- his tech tips ruined
Ommadawn's tape deck

On Wed, 30 May 2007 07:48:18 GMT, wrote:

If you don't want to install more speakers, a simple thing to do, albeit
probably with reduced sound quality, is to wire the outputs of the 8-
track deck to one of those "CD to cassette" adapters, or an FM modulator
as used with MP3 players. This would route the 8-track output to a
"cassette" that could be plugged into the Delco, or onto an FM frequency
that could be received on the Delco. This lets you use all four of the
stock speakers without much fancy wiring. snip

The FM modulator seems the best route in this case, and is an
excellent idea for this. Those cassette shells with the transfer head
inside aren't very good, much the same as the old "cassette to 8
track" adaptors of old.

If you don't want to use the CD-cassette adapter or the FM modulator,
the next possibility is to install a couple of toggle switches so you
can select whether the front speakers are connected to the stock Delco
tuner or the 8-track. You used to be able to get a single switch that
would do this, but these days it's probably easier to use two switches.

In a nutshell, you'd need two DPDT switches. You'd take the Delco radio
out of the dash and identify the two wires in the harness that go to the
left front speaker. You'd cut those two wires and splice more wire onto
the four ends you have, and route the four longer wires to where you want
to mount the toggle switches. The wires coming from the speaker (harness
side) would go to the wiper of one of the toggle switches. The wires
coming from the Delco radio (connector side) would go to one end of that
toggle switch. You would then run the left speaker wires from the
8-track deck to the other end of that toggle switch. You would then
repeat the cut, splice, connect-to-switch for the right channel.

To operate, you'd start with the Delco and the 8-track both shut off.
To listen to the Delco, make sure both switches are flipped the right
way, and then turn on the Delco and listen to the radio or a cassette.
To switch to 8-track, turn off the Delco, flip both switches the other
way, then turn on the 8-track deck. To switch back to the Delco, shut
off the 8-track deck, flip both the switches, then turn the Delco back
on. The goal is to avoid having either the Delco or the 8-track turned
on and playing without any speakers connected. Both units _probably_
don't mind playing with no speakers connected, but there is a small
chance that one or both of them might be damaged. snip

That's the rub in this situation. Running even an IC output package
without a load can cause output voltages to run as high as Vcc would
allow, and may lunch the package. Years ago, I did this same thing
with a ganged switch that would select a "one or other" output to the
speakers, and would simultaneously put an 8 ohm load on the unit not
selected, which would keep the output happy. This was, of course, an
absolute must in the tube days, since running a tube radio or
amplifier unterminated would surely arc out the output transformer in
record time due to the very high voltages that would develop in the
transformer primary with the secondary unterminated.

On 30 May 2007 03:17:55 -0700, duty-honor-country
wrote:

you can wire it to the same speakers, just make sure the delco it off
while playing the 8-track snip

DO NOT DO THIS! Of course, you know Charlie Nudo to be a fake, a liar
and a thief. NEVER parallel amplifier outputs unless you really know
what you're doing...PERIOD.

I will use a Pioneer tsx-150 surface mount speaker. the only problem
now is the power source. Were the underdash 8 track players powered
through a harness or were they spliced in?

On 30 May 2007 16:53:48 -0700, Rusty wrote:

I will use a Pioneer tsx-150 surface mount speaker. the only problem
now is the power source. Were the underdash 8 track players powered
through a harness or were they spliced in? snip

Just used a fused tap from the aux body feed bus on the fuse block
using the fuse that comes with the unit.

DeserTBoB wrote:
On Wed, 30 May 2007 07:48:18 GMT, wrote:

If you don't want to install more speakers, a simple thing to do, albeit
probably with reduced sound quality, is to wire the outputs of the 8-
track deck to one of those "CD to cassette" adapters, or an FM modulator
as used with MP3 players.

The FM modulator seems the best route in this case, and is an
excellent idea for this.

I saw where Rusty is just going to use a separate speaker, but per the
concerns about running an amp in the 8-track deck with no load, maybe
it would be good to put a resistor across each speaker output as well
as the jack for the modulator. Probably something higher-value than the
impedance it was designed for - if it was designed for 8 ohms, use maybe
16 - just so you don't load it that much and can get away with a
lower-powered resistor.

The modulator may have a couple of 32 ohm or so resistors across its
input to load the headphone output it's designed to be plugged into,
but I've never taken one apart to see.

Years ago, I did this same thing with a ganged switch that would select
a "one or other" output to the speakers, and would simultaneously put
an 8 ohm load on the unit not selected, which would keep the output
happy.

Probably as late as 10 years ago, you could walk into Radio Shack and
buy a ready-made part that would do this. You can't anymore because the
demand just isn't there; if you want to deliver square waves from about
10 Hz to 200 Hz into a huge speaker, you can get the parts for that,
though.

This was, of course, an absolute must in the tube days, since running
a tube radio or amplifier unterminated would surely arc out the output
transformer in record time due to the very high voltages that would
develop in the transformer primary with the secondary unterminated.

I'm pretty sure I understand the actual mechanisms involved, and I know
that the best thing for any amplifier is to be terminated in its design
impedance, but the informal way I think about is: a tube amp "doesn't
mind" a low-impedance or shorted output because of the natural "air gap"
in the circuit - there's only so many electrons you can shove through
that vacuum. It "hates" a high-impedance or open output because, as you
said, the voltage can sail up through the roof. A transistor amp is
just the opposite - there's a "solid" connection in the output transistor,
so it can deliver lots of power into a low-impedance or shorted output,
possibly cooking the transistor. A high-impedance or open output draws
little or no power at all, so the transistor doesn't have to do much
work. As you said, the voltage can still go up, but the positive rail
is nowhere near as high as it is with a tube amp, so it's less likely to
cause a problem. Again, this explanation is making the electrical
engineers in the audience cringe, but as one writer said, "This is not
exactly correct, but I'm telling you a story, not making an engineering
analysis."

Matt Roberds

On Fri, 01 Jun 2007 00:53:49 GMT, wrote:

I'm pretty sure I understand the actual mechanisms involved, and I know
that the best thing for any amplifier is to be terminated in its design
impedance, but the informal way I think about is: a tube amp "doesn't
mind" a low-impedance or shorted output because of the natural "air gap"
in the circuit - there's only so many electrons you can shove through
that vacuum. It "hates" a high-impedance or open output because, as you
said, the voltage can sail up through the roof.snip

Ah, but a shorted (or mismatched) secondary would draw excessive
current. On a finer quality output transformer using bifilar
windings, the trouble there would be burn-out due to overheating,
whereas the open circuit example would most likely cause transformer
failure due to arcing to the iron core.

A transistor amp is
just the opposite - there's a "solid" connection in the output transistor,
so it can deliver lots of power into a low-impedance or shorted output,
possibly cooking the transistor. A high-impedance or open output draws
little or no power at all, so the transistor doesn't have to do much
work. As you said, the voltage can still go up, but the positive rail
is nowhere near as high as it is with a tube amp, so it's less likely to
cause a problem. Again, this explanation is making the electrical
engineers in the audience cringe, but as one writer said, "This is not
exactly correct, but I'm telling you a story, not making an engineering
analysis." snip

You're correct that the chances of cooking an unterminated SS output
stage are less than it would be on a tube design, but there's another
problem...oscillation of the negative feedback circuit. Once the load
impedance is removed, the lumped constants of the output circuit and
the feedback loop change dramatically, and in some designs, can form a
tank circuit to provide an HF oscillator, which then fries the ouputs.
You're right, though, that the Vcc available limits the amount of
overvoltage damage possible, which on any car stereo (except those
annoying "thumpers" now prevalent) isn't much at all. The damage from
overheating comes from a dead short, most times. While the
characterstic output impedance of most output transistors is a
fraction of an ohm, when confronted with a much lower load impedance,
they'll usually overheat in short order.