When did decent solid state power amps become available? Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer! It seemed hard to
wean them off the transformer. Finally in the 70s...

John

On Mon, 30 Jan 2006 02:38:04 GMT, "JohnR66" wrote:

When did decent solid state power amps become available? Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer! It seemed hard to
wean them off the transformer. Finally in the 70s...

John

My 1963 Heathkit AA21 was a transformerless bridge output (neither
lead grounded nor common with the other channel) 8 Ohms was the
MINIMUL load (the included a 4 ohm wirewound in series with the
terminal labeled 4 ohms).

"JohnR66" wrote in message
...
When did decent solid state power amps become available? Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer! It seemed hard to
wean them off the transformer. Finally in the 70s...

Audio amp ICs in the 60's ?!!!

Early ss amps were generally single-ended and transformer or capacitor
coupled. More often capacitor because it was cheaper.

geoff

"JohnR66" wrote in message
...
When did decent solid state power amps become available?

**Define "decent". My Marantz Model 18 Receiver (which has been my standard
bench test amp, since 1976) was released back in 1968. It is/was direct
coupled, using complementary NPN/PNP Silicon output devices. The Model 18
was a derivative of three, earlier Marantz models - A power amp, a tuner and
a preamp.

Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

It seemed hard to
wean them off the transformer. Finally in the 70s...

**BIG difference! When attempting to squeeze the maximum efficiency and
power from minimal operating Voltage and current, it is hard to beat a
transformer. Back in the 1970s, I was obtaining 70 Watts (continuous) from
my transformer coupled car stereo power amp, into 4 Ohm loads. Impossible to
achieve without resorting to SMPS.


--
Trevor Wilson
www.rageaudio.com.au

JohnR66 wrote:
When did decent solid state power amps become available? Were they
direct, capacitor or transformer coupled to the load.

The Marantz 15 was introduced in 1968. The Marantz 16 was introduced
in 1969.

Back in the 60's when the first audio amp ICs became available for
battery powered radios and such, the engineers coupled the output
through a transformer! It seemed hard to wean them off the trans-
former. Finally in the 70s...

I know of no equipment from that era that used "audio amp IC's",
as the pretty much didn't exist at the time.

"Trevor Wilson" wrote in message
...

"JohnR66" wrote in message
...
When did decent solid state power amps become available?

**Define "decent". My Marantz Model 18 Receiver (which has been my
standard bench test amp, since 1976) was released back in 1968. It is/was
direct coupled, using complementary NPN/PNP Silicon output devices. The
Model 18 was a derivative of three, earlier Marantz models - A power amp,
a tuner and a preamp.

Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

In this case, the IC was for small battery powered radios. It was in a TO-5
can (or similar) with several radial leads. I saw it in a 1968-69 Popular
Science (or was it Popular Electronics), that had an article of how to build
a small amp around one. I don't remember the part number. BTW, wasn't the 74
series logic ICs introduced around then?
John


It seemed hard to
wean them off the transformer. Finally in the 70s...

**BIG difference! When attempting to squeeze the maximum efficiency and
power from minimal operating Voltage and current, it is hard to beat a
transformer. Back in the 1970s, I was obtaining 70 Watts (continuous) from
my transformer coupled car stereo power amp, into 4 Ohm loads. Impossible
to achieve without resorting to SMPS.


--
Trevor Wilson
www.rageaudio.com.au

"JohnR66" wrote in message
...

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?
John


I recall an NE543k (???) servo amp in a TO5, but that was 70's, not 60's....

geoff

In , on 01/30/06
at 04:54 PM, "Geoff@work" said:

"JohnR66" wrote in message
...

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?
John


I recall an NE543k (???) servo amp in a TO5, but that was 70's, not
60's....

They are not giving an exact date but Wikipedia claims "late 1960's"
for the 741

http://en.wikipedia.org/wiki/741_operational_amplifier

I can recall starting to read about IC based audio circuits in the mid
to late 60's.

---

Much better reference:

http://smithsonianchips.si.edu/augarten/p18.htm

peggs the 741 in 1968 as a successor to the 709.


-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

"JohnR66" wrote in message
...

"Trevor Wilson" wrote in message
...

"JohnR66" wrote in message
...
When did decent solid state power amps become available?

**Define "decent". My Marantz Model 18 Receiver (which has been my
standard bench test amp, since 1976) was released back in 1968. It is/was
direct coupled, using complementary NPN/PNP Silicon output devices. The
Model 18 was a derivative of three, earlier Marantz models - A power amp,
a tuner and a preamp.

Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and
such, the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?

**Irrelevant. YOU are the one claiming audio OUTPUT ICs were available in
the 1960s. Please provide the number. If my memory serves, the closest we
had in ca. 1972, where a number of chips came to market, as DRIVER ICs for
battery powered audio output applications. I am unaware of any audio output
ICs available during the 1960s.


--
Trevor Wilson
www.rageaudio.com.au

"Barry Mann" wrote in message
om...
In , on 01/30/06
at 04:54 PM, "Geoff@work" said:

"JohnR66" wrote in message
...

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?
John


I recall an NE543k (???) servo amp in a TO5, but that was 70's, not
60's....

They are not giving an exact date but Wikipedia claims "late 1960's"
for the 741

http://en.wikipedia.org/wiki/741_operational_amplifier

I can recall starting to read about IC based audio circuits in the mid
to late 60's.

---

Much better reference:

http://smithsonianchips.si.edu/augarten/p18.htm

peggs the 741 in 1968 as a successor to the 709.


-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

I remember having a 1972 color television set. It covered all the bases. It
was a primarily a tube receiver with some transistors and even had one IC.
-S

JohnR66 wrote:
Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

In this case, the IC was for small battery powered radios. It was in a TO-5
can (or similar) with several radial leads. I saw it in a 1968-69 Popular
Science (or was it Popular Electronics), that had an article of how to build
a small amp around one. I don't remember the part number.

The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?

BTW, wasn't the 74
series logic ICs introduced around then?

74 series logic IC's are NOT "audio amp IC's." They are digital logic
chips. Very different animal and irrelevant to power amps.

Barry Mann wrote:
They are not giving an exact date but Wikipedia claims "late 1960's"
for the 741

http://en.wikipedia.org/wiki/741_operational_amplifier

Much better reference:

http://smithsonianchips.si.edu/augarten/p18.htm

peggs the 741 in 1968 as a successor to the 709.

That's all very true, but look at the original context in which the
assertion was made:

"When did decent solid state power amps become available?
Were they direct, capacitor or transformer coupled to the load.
Back in the 60's when the first audio amp ICs became available
for battery powered radios and such, the engineers coupled the
output through a transformer! It seemed hard to wean them off
the transformer."

What's the implication here? It's kinda hard to say, but he seems
to be making some connection between transformer coupling and
early audio amp IC's, which have absolutely NOTHING to do with
one another. AC coupling, be it via transformers or capacitors, is
not an artifact of "the first audio amp ICs" but necessitated by the
use of single ended power supplies, resulting is a substantial
DC bias on the output stage. Further, transformers serve the
purpose of allowing matching of disparate source and load
impedances anywhere in a circuit, again, pretty much unrelated
to any notion of the "first audio amp ICs".

And, in the context of his first questions:

"When did decent solid state power amps become available?
Were they direct, capacitor or transformer coupled to the load. "

The answer is before the 1970's, as the examples I showed illustrate,
and, as well, before the use of "audio amp ICs," which really didn't
find
any widespread use until the '70's. Prior to that, solid state
amplifiers
were available in direct, capacitor and transformer coupled designs.

wrote in message
oups.com...

JohnR66 wrote:
When did decent solid state power amps become available? Were they
direct, capacitor or transformer coupled to the load.

The Marantz 15 was introduced in 1968. The Marantz 16 was introduced
in 1969.

Back in the 60's when the first audio amp ICs became available for
battery powered radios and such, the engineers coupled the output
through a transformer! It seemed hard to wean them off the trans-
former. Finally in the 70s...

I know of no equipment from that era that used "audio amp IC's",
as the pretty much didn't exist at the time.


i found the history here interesting.
http://www.uoguelph.ca/~antoon/gadgets/741/741.html

some of the early SS car radios used a single GE-3 germanium PNP 10A to
drive an inductor. IIRC it was not a transformer but some form of swinging
choke.

"Steve Urbach" wrote in
message
On Mon, 30 Jan 2006 02:38:04 GMT, "JohnR66"
wrote:

When did decent solid state power amps become available?
Were they direct, capacitor or transformer coupled to
the load. Back in the 60's when the first audio amp ICs
became available for battery powered radios and such,
the engineers coupled the output through a transformer!
It seemed hard to wean them off the transformer. Finally
in the 70s...

My 1963 Heathkit AA21 was a transformerless bridge output
(neither lead grounded nor common with the other channel)
8 Ohms was the MINIMUL load (the included a 4 ohm
wirewound in series with the terminal labeled 4 ohms).



My recollection is that there was an interstage driver transformer, and the
output was *not* bridged.

The output stage was a so-called "totem pole" configuration with 2 output
transistors effectively in series per side, 4 OPTs per channel.

This was a rather fragile amp. There was a lower-powered version the AA-22
and it was fragile as well.

IME running a 4 ohm speaker without the 4 ohm series resistor would fry this
amp pretty quickly, as would shorts.

"JohnR66" wrote in message


When did decent solid state power amps become available?


You can figure this out with some help from

http://www.roger-russell.com/magrevsr.htm

My basic spec for a *decent* SS amp would be:

(1) 30 wpc or more 20-20 KHz
(2) Less than 0.1 % THD and IM 20-20K
(3) Protected against short circuit and reactive speaker loads

I'd say 1969 or so.

Were they direct, capacitor or transformer coupled to the
load.

In 1969 there were some direct-coupled amps, but output blocking capacitors
were still popular.

For example the Heath AA15 meets my specs above (I owned an AR15) but it had
a blocking cap on the speaker leads which could oddly give a bass boost
effect with some speakers including the contemporary and popular AR3a.

The sequel AR1500 was direct coupled as was the AR-29 (1970).

Arny Krueger wrote:
"JohnR66" wrote

When did decent solid state power amps become available?

You can figure this out with some help from

http://www.roger-russell.com/magrevsr.htm

My basic spec for a *decent* SS amp would be:

(1) 30 wpc or more 20-20 KHz
(2) Less than 0.1 % THD and IM 20-20K
(3) Protected against short circuit and reactive speaker loads

I'd say 1969 or so.

The Crown DC 300 debuted in 1968. I think it would qualify.



//Walt

wrote:

JohnR66 wrote:

BTW, wasn't the 74
series logic ICs introduced around then?

74 series logic IC's are NOT "audio amp IC's." They are digital logic
chips. Very different animal and irrelevant to power amps.

Maybe he's talking about 741s and 748s? These are (were?) opamps
suitable for audio circuits and available by the early seventies. Of
course, they weren't much use for the output stage of a power amp, but
I've seen homebuilt power amps from that era built around 748s and
current follower transistors. Anybody remember Opamp Labs?


//Walt

"Walt" wrote in message
...
Arny Krueger wrote:
"JohnR66" wrote
When did decent solid state power amps become available?

You can figure this out with some help from

http://www.roger-russell.com/magrevsr.htm

My basic spec for a *decent* SS amp would be:

(1) 30 wpc or more 20-20 KHz
(2) Less than 0.1 % THD and IM 20-20K
(3) Protected against short circuit and reactive speaker loads

I'd say 1969 or so.

The Crown DC 300 debuted in 1968. I think it would qualify.

Yes, the DC300 would do and by considerable margin. It was not the best amp
for reactive loads, but it was effective at protecting itself if not the
load.

Crown says 1967:

http://www.crownaudio.com/crntime.htm

Arny Krueger wrote:

"Walt" wrote in message
...

Arny Krueger wrote:

"JohnR66" wrote

When did decent solid state power amps become available?

I'd say 1969 or so.

The Crown DC 300 debuted in 1968. I think it would qualify.

Yes, the DC300 would do and by considerable margin. It was not the best amp
for reactive loads, but it was effective at protecting itself if not the
load.

Crown says 1967:

I got the 1968 date from Gerald R. Stanley, designer of the DC-300, via
Rane's website: http://www.rane.com/par-a.html (look for the footnote
for class AB +B) Of course, he may remember wrong. Or the Crown
website may be wrong. Who can say.

http://www.crownaudio.com/crntime.htm

Thanks for the walk down memory lane.

//Walt

Trevor Wilson wrote:

"JohnR66" wrote in message
...

"Trevor Wilson" wrote in message
...

"JohnR66" wrote in message
...

capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and
such, the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?


**Irrelevant. YOU are the one claiming audio OUTPUT ICs were available in
the 1960s. Please provide the number. If my memory serves, the closest we
had in ca. 1972, where a number of chips came to market, as DRIVER ICs for
battery powered audio output applications. I am unaware of any audio output
ICs available during the 1960s.

How about 1968, for rather loose definitions of power and available?

http://www.nvg.ntnu.no/sinclair/audio/ic-10.htm

--
Eiron

I have no spirit to play with you; your dearth of judgment renders you
tedious - Ben Jonson.

"Eiron" wrote in message
...
Trevor Wilson wrote:

"JohnR66" wrote in message
...

"Trevor Wilson" wrote in message
...

"JohnR66" wrote in message
...

capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and
such, the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?


**Irrelevant. YOU are the one claiming audio OUTPUT ICs were available in
the 1960s. Please provide the number. If my memory serves, the closest we
had in ca. 1972, where a number of chips came to market, as DRIVER ICs
for battery powered audio output applications. I am unaware of any audio
output ICs available during the 1960s.

How about 1968, for rather loose definitions of power and available?

http://www.nvg.ntnu.no/sinclair/audio/ic-10.htm

**Sort of. However:

* The IC10 was hardly widely available and was not used in commercial
portable equipment (far too expensive).
* AFIK, the IC10 was a monolithic circuit, rather than an IC.
* The IC10 was not available in a TO5 can.


--
Trevor Wilson
www.rageaudio.com.au

I still enjoy my H.H. Scott Stereomaster 384 stereo receiver at my summer
cottage. It is all discrete device ss amplifier stages and was rated at
about 75 Watts per channel in those days - likely about 20 Watts rms. It
still sounds great and works 100%.

Bill
Winnipeg, MB

"JohnR66" wrote in message
...
When did decent solid state power amps become available? Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer! It seemed hard to
wean them off the transformer. Finally in the 70s...

John

On Mon, 30 Jan 2006 13:17:49 -0500, "Arny Krueger"
wrote:

"Steve Urbach" wrote in
message
On Mon, 30 Jan 2006 02:38:04 GMT, "JohnR66"
wrote:

When did decent solid state power amps become available?
Were they direct, capacitor or transformer coupled to
the load. Back in the 60's when the first audio amp ICs
became available for battery powered radios and such,
the engineers coupled the output through a transformer!
It seemed hard to wean them off the transformer. Finally
in the 70s...

My 1963 Heathkit AA21 was a transformerless bridge output
(neither lead grounded nor common with the other channel)
8 Ohms was the MINIMUL load (the included a 4 ohm
wirewound in series with the terminal labeled 4 ohms).



My recollection is that there was an interstage driver transformer, and the
output was *not* bridged.

The output stage was a so-called "totem pole" configuration with 2 output
transistors effectively in series per side, 4 OPTs per channel.

This was a rather fragile amp. There was a lower-powered version the AA-22
and it was fragile as well.

IME running a 4 ohm speaker without the 4 ohm series resistor would fry this
amp pretty quickly, as would shorts.


I could have misremembered the output configuration, and YES there was
a interstage transformer.

I drove a Pair of Altec 605A (16 ohm) so i did not worry.
Burnt out Dial lights (#47F) across the top and Noisy level controls
were the repairs that got done in the 6 years this amp was in service.

wrote in message
oups.com...
The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?

Didn't the Crown DC300 use an IC in 1967?
Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for sure.

MrT.

"Walt" wrote in message
...
I got the 1968 date from Gerald R. Stanley, designer of the DC-300, via
Rane's website: http://www.rane.com/par-a.html (look for the footnote
for class AB +B) Of course, he may remember wrong. Or the Crown
website may be wrong. Who can say.

I'd put my money on Crown knowing more about their own history than Rane.

MrT.

"Mr.T" MrT@home wrote in message
...

wrote in message
oups.com...
The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?

Didn't the Crown DC300 use an IC in 1967?

**Nope. And, points:

* The DC300A used OP amps in the pre-driver stages. The DC300 did not.
* The discussion is about POWER amps, not driver stages.

Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for sure.

**And again.


--
Trevor Wilson
www.rageaudio.com.au

On 1/30/06 6:09 PM, in article
, "Mr.T" MrT@home wrote:


wrote in message
oups.com...
The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?

Didn't the Crown DC300 use an IC in 1967?
Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for sure.

The 300 didn't. The 300 A did as did the D 150. Early stuff; i.e. 739's.
The IC 150 used (I believe) an LM301 in the high level portion and a
discrete circuit for the phono stage.

The Crowns were considered high magic by most hobbyists and unfixable
without factory support, particularly selected transistor pairs. I was
probably in grade school when Ampzilla came out in '73 or so and I'd
consider that the start of _practical_ solid state power amps without
transformers. Many of the early high power amps like Heil Ohmegas were
unmitigated dog poop and it was probably well into the Carter
Administration that you could say with a straight face solid state
power amps were as dependable as the alternative. And longer yet before
they were thought to sound good.

"Trevor Wilson" wrote in message
...
The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?
snip
* The DC300A used OP amps in the pre-driver stages. The DC300 did not.

OK, I only owned a DC300A so wasn't sure, hence the question mark.

* The discussion is about POWER amps, not driver stages.

I'm sorry, I can't see where is says *POWER AMP IC's*, only "audio amp IC's"
used in Power amps.
The difference may be too subtle for you?
An op-amp *IS* an "audio amp IC". The driver stage *IS* part of the power
amp.

Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for
sure.
**And again.

Ditto.

MrT.

"John Stone" wrote in message
...
The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?

Didn't the Crown DC300 use an IC in 1967?
Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for
sure.

The 300 didn't.

OK, that's why I used a question mark.

The 300 A did as did the D 150.

Yes, that I knew.

The IC 150 used (I believe) an LM301 in the high level portion and a
discrete circuit for the phono stage.

Correct.

MrT.

"Bret Ludwig" wrote in message
oups.com...
The Crowns were considered high magic by most hobbyists and unfixable
without factory support,

Most hobbyists still can't fix anything without factory support, so what?

I was
probably in grade school when Ampzilla came out in '73 or so and I'd
consider that the start of _practical_ solid state power amps without
transformers.

At least you give a reason for what is obviously just an opinion.

Many of the early high power amps like Heil Ohmegas were
unmitigated dog poop and it was probably well into the Carter
Administration that you could say with a straight face solid state
power amps were as dependable as the alternative.

Funny I have seen many early seventies Crowns still working.

And longer yet before they were thought to sound good.

Some say they are still no good, but I wonder if the human race will last
long enough to come up with a speaker as good?

MrT.

"Mr.T" MrT@home wrote in message
u...

"Trevor Wilson" wrote in message
...
The title of the thread is VERY clearly: early solid state power
amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?
snip
* The DC300A used OP amps in the pre-driver stages. The DC300 did not.

OK, I only owned a DC300A so wasn't sure, hence the question mark.

* The discussion is about POWER amps, not driver stages.

I'm sorry, I can't see where is says *POWER AMP IC's*, only "audio amp
IC's"
used in Power amps.

**Here is the original post:

---
When did decent solid state power amps become available? Were they direct,
capacitor or transformer coupled to the load. Back in the 60's when the
first audio amp ICs became available for battery powered radios and such,
the engineers coupled the output through a transformer! It seemed hard to
wean them off the transformer. Finally in the 70s...
---

Note the reference to a transformer.

The difference may be too subtle for you?

**Nope. No one denies the existence of ICs used as Voltage amplifiers in the
1960s.

An op-amp *IS* an "audio amp IC". The driver stage *IS* part of the power
amp.

**Part of, but not the entire power stage.


Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for
sure.
**And again.

Ditto.

**Ditto again.


--
Trevor Wilson
www.rageaudio.com.au

Mr.T wrote:
"Bret Ludwig" wrote in message
oups.com...
The Crowns were considered high magic by most hobbyists and unfixable
without factory support,

Most hobbyists still can't fix anything without factory support, so what?


Dynaco has been dead longer than Ronnie Reagan's penis and nothing
stops ST70 repair and refurbishment today. And people misguidedly
recreate Western Electric amps fifty years after they were considered
well and truly useless. But they work like thay always did.

I was
probably in grade school when Ampzilla came out in '73 or so and I'd
consider that the start of _practical_ solid state power amps without
transformers.

At least you give a reason for what is obviously just an opinion.

Many of the early high power amps like Heil Ohmegas were
unmitigated dog poop and it was probably well into the Carter
Administration that you could say with a straight face solid state
power amps were as dependable as the alternative.

Funny I have seen many early seventies Crowns still working.

Yes, if kept inside, clean, and not abused most will run forever with
only electrolytic cap replacement. In PA service they lasted a few
years which was enough. They are a challenge to fix even for the best
solid state amp techs today-fixturing and curvetracing parts is a
necessity along with bipolar current limiting supplies for
divide-and-conquer sessions.

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

Mr.T wrote:
"Bret Ludwig" wrote in message
oups.com...
The Crowns were considered high magic by most hobbyists and unfixable
without factory support,

Most hobbyists still can't fix anything without factory support, so what?


Dynaco has been dead longer than Ronnie Reagan's penis and nothing
stops ST70 repair and refurbishment today. And people misguidedly
recreate Western Electric amps fifty years after they were considered
well and truly useless. But they work like thay always did.

I was
probably in grade school when Ampzilla came out in '73 or so and I'd
consider that the start of _practical_ solid state power amps without
transformers.

At least you give a reason for what is obviously just an opinion.

Many of the early high power amps like Heil Ohmegas were
unmitigated dog poop and it was probably well into the Carter
Administration that you could say with a straight face solid state
power amps were as dependable as the alternative.

Funny I have seen many early seventies Crowns still working.

Yes, if kept inside, clean, and not abused most will run forever with
only electrolytic cap replacement. In PA service they lasted a few
years which was enough. They are a challenge to fix even for the best
solid state amp techs today-fixturing and curvetracing parts is a
necessity along with bipolar current limiting supplies for
divide-and-conquer sessions.

**Nonsense.


--
Trevor Wilson
www.rageaudio.com.au

The L'il Tiger was a popular DIY project:
http://www.swtpc.com/mholley/Popular...PE_Dec1967.htm

Daniel Meyer was one of the early voices warning about trashy open loop
performance wrapped in tons of global feedback. Mostly he was ignored.

---

http://www.emersonscott.com/hhscotinchis.html

Indicates a Scott transistorized stereo receiver in 1964 and IC's in
use in 1966.

---

I can remember having a not so great transistor "power amplifier" of
about 12 watts during the Northeast blackout of 1965 and it was at
least a year old at that time.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

John Stone wrote:

The IC 150 used (I believe) an LM301 in the high level portion and a
discrete circuit for the phono stage.

(Walt gets out his IC 150 service manual)

The ICs a

LF356H FET Op amp - master gain stage
LM301AN Op amp - gain stage for the phono preamp
MC78L18ACP - Voltage regulators

So, partial credit. (c:

The great thing about the IC 150 is that it was basically just a
switchbox with one gain stage. Minimal.

--
// Walt

On 1/31/06 7:22 AM, in article , "Walt"
wrote:

John Stone wrote:

The IC 150 used (I believe) an LM301 in the high level portion and a
discrete circuit for the phono stage.

(Walt gets out his IC 150 service manual)

The ICs a

LF356H FET Op amp - master gain stage
LM301AN Op amp - gain stage for the phono preamp
MC78L18ACP - Voltage regulators

So, partial credit. (c:

The great thing about the IC 150 is that it was basically just a
switchbox with one gain stage. Minimal.

This sounds like a different preamp and one that is much later-perhaps an
IC150A?. I am certain that the original IC150 did not have this chip
complement, and that the only IC used was in the high level stage. The rest
was discrete.

"Steve Urbach" wrote in message
...
On Mon, 30 Jan 2006 13:17:49 -0500, "Arny Krueger"
wrote:

"Steve Urbach" wrote in
message
On Mon, 30 Jan 2006 02:38:04 GMT, "JohnR66"
wrote:

When did decent solid state power amps become available?
Were they direct, capacitor or transformer coupled to
the load. Back in the 60's when the first audio amp ICs
became available for battery powered radios and such,
the engineers coupled the output through a transformer!
It seemed hard to wean them off the transformer. Finally
in the 70s...

My 1963 Heathkit AA21 was a transformerless bridge output
(neither lead grounded nor common with the other channel)
8 Ohms was the MINIMUL load (the included a 4 ohm
wirewound in series with the terminal labeled 4 ohms).

My recollection is that there was an interstage driver transformer, and
the
output was *not* bridged.

The output stage was a so-called "totem pole" configuration with 2 output
transistors effectively in series per side, 4 OPTs per channel.

This was a rather fragile amp. There was a lower-powered version the AA-22
and it was fragile as well.

IME running a 4 ohm speaker without the 4 ohm series resistor would fry
this
amp pretty quickly, as would shorts.

I could have misremembered the output configuration, and YES there was
a interstage transformer.

Not uncommon in the day. Also present in the AR amplifier, which was far
more robust but had some endemic reliability problems for an entirely
different reason.

I drove a Pair of Altec 605A (16 ohm) so i did not worry.

Yes, efficinecy and high impedance would help a lot.

Burnt out Dial lights (#47F) across the top and Noisy level controls
were the repairs that got done in the 6 years this amp was in service.

Heath didn't always use the best parts, especially potentiometers.

"Trevor Wilson" wrote in message
...

"Eiron" wrote in message
...
Trevor Wilson wrote:

"JohnR66" wrote in message
...

"Trevor Wilson" wrote in message
...

"JohnR66" wrote in message
...

capacitor or transformer coupled to the load. Back in the 60's when
the first audio amp ICs became available for battery powered radios
and such, the engineers coupled the output through a transformer!

**Oh really? Which ICs would they be?

In this case, the IC was for small battery powered radios. It was in a
TO-5 can (or similar) with several radial leads. I saw it in a 1968-69
Popular Science (or was it Popular Electronics), that had an article of
how to build a small amp around one. I don't remember the part number.
BTW, wasn't the 74 series logic ICs introduced around then?


**Irrelevant. YOU are the one claiming audio OUTPUT ICs were available
in the 1960s. Please provide the number. If my memory serves, the
closest we had in ca. 1972, where a number of chips came to market, as
DRIVER ICs for battery powered audio output applications. I am unaware
of any audio output ICs available during the 1960s.

How about 1968, for rather loose definitions of power and available?

http://www.nvg.ntnu.no/sinclair/audio/ic-10.htm

**Sort of. However:

* The IC10 was hardly widely available and was not used in commercial
portable equipment (far too expensive).
* AFIK, the IC10 was a monolithic circuit, rather than an IC.
* The IC10 was not available in a TO5 can.

You mean a hybrid IC, right?

"Trevor Wilson" wrote in message
...

"Mr.T" MrT@home wrote in message
...

wrote in message
oups.com...
The title of the thread is VERY clearly: early solid state power amps."
Can you state that the IC you SEEM to remember was relevant to
the power amp function? Which other POWER AMPS used "audio amp
IC's" in the 1960's as you claim?

Didn't the Crown DC300 use an IC in 1967?

**Nope.

http://www.crownaudio.com/pdf/amps/dc300-sm.pdf confirms that.

But the D-150 did:

http://www.crownaudio.com/pdf/legacy/D150_Schematic.pdf

And, points:

* The DC300A used OP amps in the pre-driver stages.

http://www.crownaudio.com/pdf/legacy...viceManual.pdf

confirms that. I seem to recall it was a 739.

The DC300 did not.

* The discussion is about POWER amps, not driver stages.

Both the DC-150 amplifier and IC-150 pre-amplifier did in 1970, for sure.

**And again.

Confirm:

http://www.crownaudio.com/pdf/amps/ic150sm3.pdf