[Tobiah]

I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually
a nice set of monitors. My main concern is getting
an amp that is as accurate and transparent as possible.
It should deliver 25 to 100 watts for small room listening.

I envision it with a single ergonomic knob that controls
volume, and that's it. I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Now, I have my recording room speakers, but I'd also like
to use my DAW to provide music to an adjoining room, and
an outside speaker pair. I could see having multiple speaker
outs that are switchable. Other than that, perhaps I would
want a separate amp for each in order to control the volume
on each pair separately. I'm not sure.

Thanks,

Tobiah

[Peter Larsen[_2_]]

Tobiah wrote:

I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually
a nice set of monitors. My main concern is getting
an amp that is as accurate and transparent as possible.
It should deliver 25 to 100 watts for small room listening.

I use a very nice cambridge poweramp, something 2 X "50" for just that,
from the size of the the powersupply it is a 2X40, but the specs say
more.

I envision it with a single ergonomic knob that controls
volume, and that's it.

You just need say a three step attenuator, something like -15, -20 and
-25 dB, that should put you sufficiently in the ballpark for regularing
listening level from the Mackie.

I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Now, I have my recording room speakers, but I'd also like
to use my DAW to provide music to an adjoining room, and
an outside speaker pair. I could see having multiple speaker
outs that are switchable. Other than that, perhaps I would
want a separate amp for each in order to control the volume
on each pair separately. I'm not sure.

A NAD 906 multichannel amp comes to mind then, you can bridge two pairs
for 2 x "100" and use one pair for adjoining, or simply use one channel
pair for each set, must be available 2'hand on some garage sale. It
contains 3 times the poweramp from the NAD302, but that same poweramp
seems to me to sound better re-packaged, and better even when bridged.
Nice heavy thing .... seems like it has a real psu.

Tobiah

Kind regards

Peter Larsen

[Frank Stearns]

Tobiah writes:

I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually
a nice set of monitors. My main concern is getting
an amp that is as accurate and transparent as possible.
It should deliver 25 to 100 watts for small room listening.

I envision it with a single ergonomic knob that controls
volume, and that's it. I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Now, I have my recording room speakers, but I'd also like
to use my DAW to provide music to an adjoining room, and
an outside speaker pair. I could see having multiple speaker
outs that are switchable. Other than that, perhaps I would
want a separate amp for each in order to control the volume


Most of us always want less for more, but it seems you're pushing the envelope on
those parameters of cheap/decades-reliable/transparent.

At $200, you can probably only really get the first one; maybe a hint at the third,
but likely just a hint. Certainly "decades reliable" is out the window, mainly
because of the really, really crap parts you'll find at that price point. (Try 3-5
years, with a bit of luck.)

A Bryston gets you a 20 year warranty, and their 2B or 3B models are in that power
range, but be prepared to spend well north of US$1200.00, even used.

The newer series Brystons even sound pretty good, as they did some smart things in
the VAS when that series was redesigned a number of years ago.

There are some fairly good pro-sumer amps in the $500 range that will get you a
little closer to sound and reliability ideals.

Now, it's easy to start a holy war here on sonic quality, but IMHO Class-A will get
you uber transparancy, if properly applied. Pass Labs comes to mind, but now you're
north of $2K, $3K, even $4K (not to mention the heat generation and power
consumption issues).

And while cheap amps have the potential to "sound better" than similar amps did
20-30 years ago, remember that a power amp is essentially a modulated power supply.
Good power supplies simply cost money for a laundry list of reasons, often relating
to many aspects of: "Ah kinna change the laws of physics, Captain" (Lt. Cmd Scott to
Captain Kirk, more than once).

But, it'll be interesting to see what people have to say.

Good luck with it,

Frank
Mobile Audio
--

[Peter Larsen[_2_]]

Tobiah wrote:

I envision it with a single ergonomic knob that controls volume, and
that's it.

You just need say a three step attenuator, something like -15, -20 and
-25 dB, that should put you sufficiently in the ballpark for regularing
listening level from the Mackie.

Oh, so your amp has not even a volume knob? Still, wouldn't I
be able to control the volume ok from the Mackie? Why would I need
the attenuator?

Amp sensitivity for full output power is usually in the 1 volt range,
your mackie will have a max output in the 8 volt range. So if you do NOT
put an inline attenuator of some type in between you will risk to blow
up eardrums, cochlea and less important loudspeakers or drive units
thereof, the latter are replaceable, but your sense of hearing,
especially the cochlea, is not. I don't know the efficiency of your
loudspeakers, so I can't tell you exactly what to main for, but the
relevant attenuation is in the 20 dB range +/- perhaps 8 dB. As example:
I use 12 dB fixed attenuation to match household sized amplifier to
midiman sound card. Poweramplifiers for use in a diy household should
always be atttenuated enough to allow not2worry hotplugging ... at least
of those that are not connected directly to mid and/or treble units.

Another "oldie" amp model to look for is the Rotel RB960-BX, but frankly
the NAD906 is cleaner sounding, the issue with the Rotel may be the
opamp stage that allows bridging, but I never bothered investigating. I
like it a lot, it is just that I was so pleasantly surprised when
listning to the 906 in bridging mode yesterday. It has input level
adjustment. It has been unused for a couple of years and the reason I
turned it on was to check whether it should be considered junk or "for
repair", I took it out of use as amp for a small active three-way
because the treble channel pair suddenly got very hot. I never did
investigate whether it was the amp or the cross-over, but I just got me
some alternative opamps for that cross-over, an old IFM. If it had been
the poweramp I reckon that channel pair hadn't worked when I finally
checked it.

I may have confused you and your mileage may vary wildly.


Kind regards

Peter Larsen

[Harry Trueman]

On Mon, 18 Jul 2011 16:42:54 GMT, Tobiah wrote:

I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually
a nice set of monitors. My main concern is getting
an amp that is as accurate and transparent as possible.
It should deliver 25 to 100 watts for small room listening.

I envision it with a single ergonomic knob that controls
volume, and that's it. I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Now, I have my recording room speakers, but I'd also like
to use my DAW to provide music to an adjoining room, and
an outside speaker pair. I could see having multiple speaker
outs that are switchable. Other than that, perhaps I would
want a separate amp for each in order to control the volume
on each pair separately. I'm not sure.

Thanks,

Tobiah

Uh, Archer, Realistic?

[Tobiah]

I envision it with a single ergonomic knob that controls volume, and
that's it.

You just need say a three step attenuator, something like -15, -20 and
-25 dB, that should put you sufficiently in the ballpark for regularing
listening level from the Mackie.

Oh, so your amp has not even a volume knob? Still, wouldn't I
be able to control the volume ok from the Mackie? Why would I need
the attenuator?

[Tobiah]

Most of us always want less for more, but it seems you're pushing the
envelope on those parameters of cheap/decades-reliable/transparent.

At $200, you can probably only really get the first one; maybe a hint at
the third, but likely just a hint.

I see home theater receivers going for around $500, and they seem
to do a lot of stuff. I don't know anything about home theater.
I was just thinking that if all I wanted was an amp only, that it
would be quite a bit cheaper.

Right now, I'm using a class-a JVC receiver from the 80's. Maybe
it's fine for what I'm doing. I thought it would be nice to cut out
the radio receiver, and equalizer, and phono input and tape monitor
etc. and get down to a decent amplifier-only that might end up sounding
better. It is quite possible that I won't be able to tell the difference
in sound anyway. If so, I would still consider a new amp if I could get
one that was substantially smaller than the JVC, which has a much larger
footprint than the 1202.

Tobiah

[Tobiah]

Amp sensitivity for full output power is usually in the 1 volt range,
your mackie will have a max output in the 8 volt range.

So couldn't I promise not to turn the Mackie up very far?
What equipment then, are they expecting a person to hook up to
that amp?

I noticed that many amps accept the XLR inputs, which the Mackie
has outputs for. Would such a connection solve the level problems?

Thanks,

Toby

[Scott Dorsey]

In article , Tobiah wrote:
I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually
a nice set of monitors. My main concern is getting
an amp that is as accurate and transparent as possible.
It should deliver 25 to 100 watts for small room listening.

I envision it with a single ergonomic knob that controls
volume, and that's it. I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Buy a used Adcom GFA 535. Add a volume control.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Harry Trueman]

On 18 Jul 2011 16:06:10 -0400, (Scott Dorsey) wrote:

In article , Tobiah wrote:
I want to amplify the main outs of my Mackie 1202VLZ Pro
into my current Energy stereo speakers, and eventually
a nice set of monitors. My main concern is getting
an amp that is as accurate and transparent as possible.
It should deliver 25 to 100 watts for small room listening.

I envision it with a single ergonomic knob that controls
volume, and that's it. I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Buy a used Adcom GFA 535. Add a volume control.
--scott

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

[Dec [Cluskey]]

I envision it with a single ergonomic knob that controls
volume, and that's it. *I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Tobiah

I have used, since God was a boy, a Quad 303 ..... bought new ...
serviced twice in its life and is probably the best studio amp I have
ever used .... I power my studio NS10's with it and have a switched
A .... B and A&B unit which adds in Kef Correlli speakers ....
altogether the best near field situation I have heard.

It is interesting to realise that the mainstay of all BBC studio
audience speakers [no matter what venue] in the 60's, 70's was the
Quad 303 ... that is why I bought mine. Built like a brick [and looks
like one] no volume control or EQ ... just an amp.

I added a simple wall mounted volume control which acts as a main
system attenuator ... and acts as a simple on/off for recording with
earphones.

I should imagine they are easily and cheaply available on Ebay?

Dec [Cluskey] http://www.deccluskey.co.uk/blog

[Frank Stearns]

"Soundhaspriority" writes:

"Tobiah" wrote in message
...
beast.

-snips-

Right now, I'm using a class-a JVC receiver from the 80's. Maybe
it's fine for what I'm doing.

If you have a Class-A amp from the 80's, stick with it. You can't replace it
at reasonable cost.

I'd be surprised that anything labeled a "receiver" is actually class-A. Can you
tell us where you saw the "Class A" label on this unit, and in what context?

Does it put out LOTS of heat, even with no signal present? Note that "class A" might
be some sort of quality rating from the manufacturer's marketing department, and not
the actual topology of the power amp circuits. It's possible too that the preamp and
line-level signal paths are class A, but it's still more than likely that the power
amp sections are AB.

If the power amp section truly is class-A, Bob is right -- hang onto that beast.

Be aware, though, that at 25 years you're at or perhaps past the useful life of the
electrolytic caps in the unit, particularly the PS caps. (Any hum? Does it sound
weak in the low end?)

The unit might well be worth re-capping if it's a good design and good build
quality.

Frank
Mobile Audio


--

[Scott Dorsey]

Harry Trueman wrote:

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

Try and do an A-B between the Samson and a cleaner amplifier like the
Adcom, especially at very low power levels. You'll be surprised.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Harry Trueman]

On 18 Jul 2011 21:34:34 -0400, (Scott Dorsey) wrote:

Harry Trueman wrote:

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

Try and do an A-B between the Samson and a cleaner amplifier like the
Adcom, especially at very low power levels. You'll be surprised.
--scott

I believe you. Going back decades, I went from Dynaco to Phase Linear
to Crown to Hafler. The amp I was most impressed with was the Crests
we used for live sound reinforcement. They were "tanks". But they
belonged to the band. I think I recall the Phase Linear being serviced
maybe 5X. I'm quite happy with the Samson, thank you.

[Trevor]

"Tobiah" wrote in message
...
Amp sensitivity for full output power is usually in the 1 volt range,
your mackie will have a max output in the 8 volt range.

So couldn't I promise not to turn the Mackie up very far?

The S/N ratio will be lower if you simply turn the Mackie down, an
attenuator reduces both the signal and noise.

Trevor.

[Harry Trueman]

That might be the way for him to go. Good quality, cheap. If you don't
mind risking, "No returns accepted".

[Peter Larsen[_3_]]

Tobiah wrote:

Amp sensitivity for full output power is usually in the 1 volt range,
your mackie will have a max output in the 8 volt range.

So couldn't I promise not to turn the Mackie up very far?
What equipment then, are they expecting a person to hook up to
that amp?

Household variety preamp. With those extra input attenuation is wise as
well.

I noticed that many amps accept the XLR inputs, which the Mackie
has outputs for. Would such a connection solve the level problems?

No. A poweramplifier with an input level control would, that applies btw. to
the NAD 906.

Thanks,

You're welcome.

Toby

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Harry Trueman wrote:

[the quest for the poweramp]

Buy a used Adcom GFA 535. Add a volume control.

--scott

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

You missed the barn by a furlong, suggested amplifier - just as the one
Scott suggested - does not have an input level control.

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Frank Stearns wrote:

"Soundhaspriority" writes:

"Tobiah" wrote in message
...
beast.

-snips-

Right now, I'm using a class-a JVC receiver from the 80's. Maybe
it's fine for what I'm doing.

If you have a Class-A amp from the 80's, stick with it. You can't
replace it at reasonable cost.

I'd be surprised that anything labeled a "receiver" is actually
class-A. Can you tell us where you saw the "Class A" label on this
unit, and in what context?

It is a "new class a" amp, they were de la mode in the 1980'es, and can be
quite sweet sounding, I'm using a two for compression driver powering, they
are great at not delivering power.

Be aware, though, that at 25 years you're at or perhaps past the
useful life of the electrolytic caps in the unit, particularly the PS
caps. (Any hum? Does it sound weak in the low end?)

Yes, my old Radford STA25's manual said 17 years life expectancy, but it is
probably still running fine with its new owner since 1980. I still miss it
sometimes ...

The unit might well be worth re-capping if it's a good design and
good build quality.

Amps that are frequently powered up and used at household operating
temperatures tend to last very well, what is bad is to leave them unused and
forget to power the up for a week say once every 6 to 12 months.

Frank
Mobile Audio

Kind regards

Peter Larsen

[Peter Larsen[_3_]]

Trevor wrote:

"Tobiah" wrote in message
...

Amp sensitivity for full output power is usually in the 1 volt
range, your mackie will have a max output in the 8 volt range.

So couldn't I promise not to turn the Mackie up very far?

The S/N ratio will be lower if you simply turn the Mackie down, an
attenuator reduces both the signal and noise.

Did you forget a "than" between "lower" and "if"?

Trevor

Kind regards

Peter Larsen

[Trevor]

"Peter Larsen" wrote in message
k...
Amp sensitivity for full output power is usually in the 1 volt
range, your mackie will have a max output in the 8 volt range.

So couldn't I promise not to turn the Mackie up very far?

The S/N ratio will be lower if you simply turn the Mackie down, an
attenuator reduces both the signal and noise.

Did you forget a "than" between "lower" and "if"?

Nope, overall S/N ratio will be lower (noise will be higher) if you simply
turn the Mackie output down while leaving the power amp gain at maximum. How
much difference is another matter entirely :-)

Trevor.

[Peter Larsen[_2_]]

Harry Trueman wrote:

OK, I guess I know what you're "driving " at. The board I'm using is
actually a multitrack with a comsumer output of only .775mv @ 0db for
typical line level out. If his Mackie is a 8v-10v out then he might
blow out a window in the process of absent mindedly hot swapping
inputs with anything like an 800w samson.

The consequences of hotplugging something that does not establish ground
first depend on input sensitivity rather than on output from whatever is
in the other end of the wire.

That's why I like the 800w I guess (headroom?).

Headroom is nice, but it is not nice to have loudspeaker damage, I
repaired a cross-over for a friend with a pair of Kenwood L07's - he was
lucky, the accidental hotplugging he did only caused a 7 watt ceramic
midrange attenuation resistor to blow.

I have accidentally left it on for days, and it's
so quiet that I don't realize it's on. Don't know if I'd personally be
happy with just 60 or so watts but that's just a product of me being
weened on hard rock and the need to "blast" it occasionally .

Comments not possible, I don't know the effiency of your loudspeakers
nor the size of your listening room and your listening distance.

He
suggests I think that he wants to be able to control the volume on the
remote sets of speakers so he could always add another amp, also with
attenuator, later on using the additional outputs on the Mackie or
just use the JVC receiver for that, if it's not one of those home
theater things. No?

Why not get three stereo amplifiers in one box then, Rotel also
makes/made one, also a very good amp. And that one has attenuators on
the front. It is a wonderful amp to have when comparing loudspeakers.

I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Good luck with that. I've always wanted an active tri-amp
configuration for $200 because I'm not Donald Trump and it has 8X the
transit response as passive at equal wattage....but

The example product, the NAD 906 must have been in the USD 350 range new
in 1997. That would imply a second hand price below USD 200 now. The 6
channel Rotel, also three stereo amps in one box, ought to also be
reasonably priced, mine cost me the equivalent of USD 275 a couple of
years ago.

I find it easy to believe that the Adcom suggested by Scott is a
possibly better choice, as is the additional headroom from the Behringer
Arny suggested. Horses for courses and it is the OP who knows his
quality and power-requirements best but quality beats power in most home
listening context just as power beats quality in most PA contexts
because a larger amp that does not clip sounds sweeter than a smaller
one that does.

The Yamaha P1600 is btw. a very good amplifier, it is from the pa range
so it does have a fan but it is modestly noisy and has clarity as well
as punch and is not "toy class". An Ebay search including expired
auctions may be a good way to find the pricerange for something.


Kind regards

Peter Larsen

[Arny Krueger[_4_]]

"Tobiah" wrote in message
...

Amp sensitivity for full output power is usually in the 1 volt range,
your mackie will have a max output in the 8 volt range.

So couldn't I promise not to turn the Mackie up very far?
What equipment then, are they expecting a person to hook up to
that amp?

I noticed that many amps accept the XLR inputs, which the Mackie
has outputs for. Would such a connection solve the level problems?


No. Balanced XLR inputs have the effect of doubling the amp's sensitivity as
compared to unbalanced.RCAs.

Many consoles have control room outputs that may have a more favorable level
situation.

Or, you just use a power amp with input attenuators and turn the attenuators
down and keep them there.

BTW my choice for this application would be an amp that I have several years
of experience with - the Behringer A500. It's a rotten 500 watt amp, but a
very nice 200-250 watt amp @ 100-125 wpc.

[Harry Trueman]

On Tue, 19 Jul 2011 06:07:30 +0100, "Peter Larsen"
wrote:

Harry Trueman wrote:

[the quest for the poweramp]

Buy a used Adcom GFA 535. Add a volume control.

--scott

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

You missed the barn by a furlong, suggested amplifier - just as the one
Scott suggested - does not have an input level control.

Kind regards

Peter Larsen






OK, I guess I know what you're "driving " at. The board I'm using is
actually a multitrack with a comsumer output of only .775mv @ 0db for
typical line level out. If his Mackie is a 8v-10v out then he might
blow out a window in the process of absent mindedly hot swapping
inputs with anything like an 800w samson. That's why I like the 800w I
guess (headroom?). I have accidentally left it on for days, and it's
so quiet that I don't realize it's on. Don't know if I'd personally be
happy with just 60 or so watts but that's just a product of me being
weened on hard rock and the need to "blast" it occasionally . He
suggests I think that he wants to be able to control the volume on the
remote sets of speakers so he could always add another amp, also with
attenuator, later on using the additional outputs on the Mackie or
just use the JVC receiver for that, if it's not one of those home
theater things. No?

I could see spending $200 on it if
I thought it was made to last decades, and was going to be
able to give me very high quality amplification.

Good luck with that. I've always wanted an active tri-amp
configuration for $200 because I'm not Donald Trump and it has 8X the
transit response as passive at equal wattage....but

[Harry Trueman]

On Tue, 19 Jul 2011 12:14:02 +0200, Peter Larsen
wrote:

Harry Trueman wrote:




Kind regards

Peter Larsen


The consequences of hotplugging something that does not establish ground
first depends on input sensitivity rather than on output from whatever is
in the other end of the wire.

Who said anything about establishing ground? I might do this when I
absent mindedly plug the drum machine back into channels 7/8 without
checking the faders first. I am just guessing that the OP is recording
tracks and using his mackie and monitors to do his craft to later
listen in a remote environment.

Headroom is nice, but it is not nice to have loudspeaker damage, I
repaired a cross-over for a friend with a pair of Kenwood L07's - he was
lucky, the accidental hotplugging he did only caused a 7 watt ceramic
midrange attenuation resistor to blow.

Thanks for sharing that. I have a silly philosophy that I've always
used over powerful amps to allow the amp to take control of the
physical aspects of the speaker. Not the other way around. In
otherwords, having the faders set at 2-3 as opposed to 8-0 produces a
better quality output. I've "never" blown a speaker. Really! We did
let Blackfoot use our PA one night and they did blow the monitor
speakers after which they prompty reimbursed us full cost without us
asking. We also let the Little River Band use our PA and they remarked
how good it sounded (unbelieveable 5 part vocals those chaps have)

Comments not possible, I don't know the effiency of your loudspeakers
nor the size of your listening room and your listening distance.

I would think that if you did, you'd be spying on me...LOL. But I'm
using 3 way Pioneers with 15", Altec Lansing 83's which I occasionally
switch with JBL D38 Decade (or is it decayed?) speakers as I have 4
sets. I don't have access to NS10's so. These el cheapo's are fine
with me. The last system we used was 12,000 watts of Crest, Carver
tri-amp w/JBL drivers. This is the system "Little Liver Band" at a
party used (typo intentional) with 4 stacks on each side was enough to
blast RFK stadium and get the Redskin cheerleaders gyrating the
drummer out of his throne. The sound on this system was so crisp, fine
and quiet that you could see the audio.

Why not get three stereo amplifiers in one box then, Rotel also
makes/made one, also a very good amp. And that one has attenuators on
the front. It is a wonderful amp to have when comparing loudspeakers.

On your suggestion, he should look at this also.

[Scott Dorsey]

In article ,
Harry Trueman wrote:
On 18 Jul 2011 21:34:34 -0400, (Scott Dorsey) wrote:

Harry Trueman wrote:

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

Try and do an A-B between the Samson and a cleaner amplifier like the
Adcom, especially at very low power levels. You'll be surprised.

I believe you. Going back decades, I went from Dynaco to Phase Linear
to Crown to Hafler. The amp I was most impressed with was the Crests
we used for live sound reinforcement. They were "tanks". But they
belonged to the band. I think I recall the Phase Linear being serviced
maybe 5X. I'm quite happy with the Samson, thank you.

The later Haflers aren't bad at all, and actually the cheapest line from
QSC is a lot better than I'd ever expected.

But nothing blows up like a Phase Linear.

"I was asking a union hand at the Oakland Paramount about the last time the
fire-curtain had been used. The answer: not since the sound companies
stopped using Phase Linears in their racks."
--T.Alan

I have personally seen one of the Phase Linear 700s spewing sparks three
feet in the air after the output transistors failed, at the Little Five
Points Pub in Atlanta. Quality workmanship, that. They don't make them
like that any more.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Harry Trueman]

On 19 Jul 2011 10:28:52 -0400, (Scott Dorsey) wrote:

In article ,
Harry Trueman wrote:
On 18 Jul 2011 21:34:34 -0400, (Scott Dorsey) wrote:

Harry Trueman wrote:


As a school kid the Dynaco and Hafler kits were fun to assemble and
made me think I knew something about audio electronics, which I don't.
Just would whip out the Nokorode and a soldering pencil and a
screwdriver and zip, I built my own Pre and Power amp. You could plug
things in them like you would a 2 channel board. Later I would
discover that that's not possible with a "receiver" and was
disappointed much like OP. I've heard good things about QSC. But then
again, back in the day they told me that Phase Linear was state of the
art and I believed it. Can't believe I was so stupid as to think each
time would be the last repair. Serviceman said after 3X, "This belongs
in your living room, not PA". He didn't want to service it.

They don't make them like that any more.

Thank God.

PS the samson is not 1200w bridged. Apparently I read the specs for
the F1200 which is in the same manual. It's 800w. Need to eat more
carrots. Just like I thought the Hafler had .002% THD. Wrong again?

[Scott Dorsey]

Harry Trueman wrote:
As a school kid the Dynaco and Hafler kits were fun to assemble and
made me think I knew something about audio electronics, which I don't.
Just would whip out the Nokorode and a soldering pencil and a
screwdriver and zip, I built my own Pre and Power amp. You could plug
things in them like you would a 2 channel board. Later I would
discover that that's not possible with a "receiver" and was
disappointed much like OP. I've heard good things about QSC. But then
again, back in the day they told me that Phase Linear was state of the
art and I believed it. Can't believe I was so stupid as to think each
time would be the last repair. Serviceman said after 3X, "This belongs
in your living room, not PA". He didn't want to service it.

It WAS state of the art. It got an outrageous amount of power out of a small
package, and using the cheapest possible output transistors too. Nobody had
ever managed that kind of power density before. However, there was a
downside...

PS the samson is not 1200w bridged. Apparently I read the specs for
the F1200 which is in the same manual. It's 800w. Need to eat more
carrots. Just like I thought the Hafler had .002% THD. Wrong again?

The Samson power ratings basically come out of someone's butt in the
marketing department. Try measuring FTC method with a one-third power
warmup and see if it even survives the measurement...
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Harry Trueman]

On 19 Jul 2011 11:27:12 -0400, (Scott Dorsey) wrote:

Harry Trueman wrote:


The Samson power ratings basically come out of someone's butt in the
marketing department. Try measuring FTC method with a one-third power
warmup and see if it even survives the measurement...
--scott

Nope. Not interested in "browning" it out, dude. The circuit protect
wouldn't kick out and would probably would toast it. Don't know why
discussing samson. I'm just glad it's not a Kustom or Peavey. And it's
definately not something special.

Cheers

[Audio1]

On 7/19/2011 11:14 AM, Harry Trueman wrote:
...back in the day they told me that Phase Linear was state of the
art and I believed it. Can't believe I was so stupid as to think each
time would be the last repair. Serviceman said after 3X, "This belongs
in your living room, not PA". He didn't want to service it.

They don't make them like that any more.

Thank God.

Yes, the main problem with Phase Linears was how they were made, a big
power transformer and big supply caps hung on thin sheet metal. Then
there were those sheet metal transistor covers that would short out the
transistors if you bumped them or simply looked at them wrong while
messing around the back of the amp.

I worked with a sound company that made brackets so the transformers and
caps could be bolted to the sides of the racks to take the stress off
the chassis, added B+ and B- fuses to each channel and threw out the
transistor covers. That increased the reliability a great deal and the
fuses kept things from catching fire. They ran probably 35-40 200B's,
400B's and 700B's and had to fix maybe 1-2 a year, usually after a blown
driver or rain storm.

I have a couple of XPL-909's I took out of one major catastrophe. What
usually happened is the output transistors would short, take out the
driver stage which would burn a hole in the circuit board, hence the
moniker 'Flame Linear.'

Bob Heil put purple front panels on 700's and sold 'em under his name,
said sound co. had a couple of those.

[Tobiah]

Right now, I'm using a class-a JVC receiver from the 80's. Maybe it's
fine for what I'm doing.

If you have a Class-A amp from the 80's, stick with it. You can't
replace it at reasonable cost.

I'd be surprised that anything labeled a "receiver" is actually class-A.
Can you tell us where you saw the "Class A" label on this unit, and in
what context?

It's a JVC R-S33. It says "Super-A" on the front, but the original
literature touted the unit as a "class A". A quick google search
seems to suppport that it's class A - I'm not sure.

Does it put out LOTS of heat, even with no signal present? Note that
"class A" might be some sort of quality rating from the manufacturer's
marketing department, and not the actual topology of the power amp
circuits. It's possible too that the preamp and line-level signal paths
are class A, but it's still more than likely that the power amp sections
are AB.

I wouldn't say "LOTS" of heat, no. The entire top of the unit is vented,
and it does get warm.

If the power amp section truly is class-A, Bob is right -- hang onto
that beast.

Be aware, though, that at 25 years you're at or perhaps past the useful
life of the electrolytic caps in the unit, particularly the PS caps.
(Any hum? Does it sound weak in the low end?)

I don't notice any weakness in the sound really. I originally just
thought that some modern amp-only unit might save me some desk space
and through better technology, get me better (in some way) sound.

Thanks,

Toby

[Tobiah]

I'd be surprised that anything labeled a "receiver" is actually
class-A. Can you tell us where you saw the "Class A" label on this
unit, and in what context?

It's a JVC R-S33. Â*It says "Super-A" on the front, but the original
literature touted the unit as a "class A". Â*A quick google search seems
to support that it's class A - I'm not sure.

I found a description he

http://www.canuckaudiomart.com/details/174848-
jvc_rs33_stereo_receiver_original_service_manual_w ith_full_schematic_and_more

Sounds to me a lot like the marketing department's description of an
ordinary Class AB output stage...

Well, there you are. Anyway, I was just wondering whether
I could replace this thing with something smaller and simpler
that would sound better, for around $200.

Thanks,

Tobiah

[Scott Dorsey]

Tobiah wrote:

I'd be surprised that anything labeled a "receiver" is actually
class-A. Can you tell us where you saw the "Class A" label on this
unit, and in what context?

It's a JVC R-S33. Â*It says "Super-A" on the front, but the original
literature touted the unit as a "class A". Â*A quick google search seems
to support that it's class A - I'm not sure.

I found a description he

http://www.canuckaudiomart.com/details/174848-
jvc_rs33_stereo_receiver_original_service_manual_ with_full_schematic_and_more

Sounds to me a lot like the marketing department's description of an
ordinary Class AB output stage...

Well, there you are. Anyway, I was just wondering whether
I could replace this thing with something smaller and simpler
that would sound better, for around $200.

Yes. Try a used GFA-535, as I said earlier.

There are some of the 535s that were shipped with a volume control option,
but most of the used ones will be fixed gain.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Steve King]

"Scott Dorsey" wrote in message
...
Tobiah wrote:

I'd be surprised that anything labeled a "receiver" is actually
class-A. Can you tell us where you saw the "Class A" label on this
unit, and in what context?

It's a JVC R-S33. Â It says "Super-A" on the front, but the original
literature touted the unit as a "class A". Â A quick google search
seems
to support that it's class A - I'm not sure.

I found a description he

http://www.canuckaudiomart.com/details/174848-
jvc_rs33_stereo_receiver_original_service_manual _with_full_schematic_and_more

Sounds to me a lot like the marketing department's description of an
ordinary Class AB output stage...

Well, there you are. Anyway, I was just wondering whether
I could replace this thing with something smaller and simpler
that would sound better, for around $200.

Yes. Try a used GFA-535, as I said earlier.

There are some of the 535s that were shipped with a volume control option,
but most of the used ones will be fixed gain.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

GFA 535s have been selling on Ebay from $60 to $120 each. That should meet
your budget.

Steve King

[swanny]

On 20/07/2011 12:28 AM, Scott Dorsey wrote:
In article ,
Harry Trueman wrote:
On 18 Jul 2011 21:34:34 -0400, (Scott Dorsey) wrote:

Harry Trueman wrote:

I picked up a Sampson F800 (1200 bridged) to run from the cheapo
Yamaha and the master slider works quite nicely. That is to say that I
would have to "try" to blow the speakers or cochlea. Audio tapered
slider maybe? Clean as a whistle.

Try and do an A-B between the Samson and a cleaner amplifier like the
Adcom, especially at very low power levels. You'll be surprised.

I believe you. Going back decades, I went from Dynaco to Phase Linear
to Crown to Hafler. The amp I was most impressed with was the Crests
we used for live sound reinforcement. They were "tanks". But they
belonged to the band. I think I recall the Phase Linear being serviced
maybe 5X. I'm quite happy with the Samson, thank you.

The later Haflers aren't bad at all, and actually the cheapest line from
QSC is a lot better than I'd ever expected.

But nothing blows up like a Phase Linear.

"I was asking a union hand at the Oakland Paramount about the last time the
fire-curtain had been used. The answer: not since the sound companies
stopped using Phase Linears in their racks."
--T.Alan

I have personally seen one of the Phase Linear 700s spewing sparks three
feet in the air after the output transistors failed, at the Little Five
Points Pub in Atlanta. Quality workmanship, that. They don't make them
like that any more.
--scott

Likewise. Back in the 70's I saw two LF horn enclosures catch on fire
after the fans in the PL700's stopped. Sound was immaterial once the
crowd realised we had a pyrotechnics show as well

[Peter Larsen[_3_]]

Trevor wrote:

Right, looks like a straight forward description of class AB.
Obviously NOT class A.

My understanding is that they are using a dynamic bias rather than a fixed
bias in the "new class a" ploys.

Trevor

Kind regards

Peter Larsen

[Trevor]

"Peter Larsen" wrote in message
k...
Right, looks like a straight forward description of class AB.
Obviously NOT class A.

My understanding is that they are using a dynamic bias rather than a fixed
bias in the "new class a" ploys.

Perhaps some are, just as others use a dynamic rail voltage etc. However
this is not mentioned in the reference provided, and does not constitute
class A in any case, whether "new", or old.

Trevor.

[Frank Stearns]

"Peter Larsen" writes:

Trevor wrote:

Right, looks like a straight forward description of class AB.
Obviously NOT class A.

My understanding is that they are using a dynamic bias rather than a fixed
bias in the "new class a" ploys.

Ah yes, jogs the memory.

At one time, dynamic bias was quite the thing in some circles, IIRC. Have no idea
how well it worked, though.

I think the concept probably fell out of favor because it was way more trouble than
simple fixed-bias AB.

And to the OP: @ 40 wpc, if truly class-A, the thing would be massively heat-sinked,
uncomfortably hot to touch all the time it was on, weight a ton, and you could
easily heat the room (a couple of rooms?) with it.

If you want to swap it out for something more compact, seems like some good
suggestions have been made. But who knows -- you might have a sleeper. Try
"Audiogon" or one of those audio gear sales sites. They might laugh, or
you might find some devotees who really like that model, and its sale would cover
your replacement.

Good luck with it,
Frank
Mobile Audio

--

[Peter Larsen[_2_]]

Scott Dorsey wrote:

Frank Stearns wrote:

At one time, dynamic bias was quite the thing in some circles,
IIRC. Have no idea how well it worked, though.

It worked okay. It gave low distortion at low levels, and as you
got to higher levels the crossover distortion increased substantially
but since it made less of a contribution to the total signal it
wasn't a big deal.

I'm using a pair of "new class a + dc servo" Sansui B55's to power
compression drivers, one of those with so much input attenuation that 1
volt in produces 0.6 volts out. They were good out of the shrink wrap
and once the input coupling cap was replaced with polypropylene and the
octave band analyzer display card was removed they got extemely
transparent.

I think the concept probably fell out of favor because it was
way more trouble than simple fixed-bias AB.

I think it mostly fell out of favor because the numbers on the marketing
handouts didn't look as good as a fixed-bias amplifier. You measure the
distortion at full power, where it's highest.

And higher component count and manufacturing complexity and the overall
loss of clarity in early digital stopping the quality wars. Digital was
perfect so there was nothing more to improve, remember?

Kind regards

Peter Larsen

[Scott Dorsey]

Frank Stearns wrote:

At one time, dynamic bias was quite the thing in some circles, IIRC. Have no idea
how well it worked, though.

It worked okay. It gave low distortion at low levels, and as you got to
higher levels the crossover distortion increased substantially but since it
made less of a contribution to the total signal it wasn't a big deal.

I think the concept probably fell out of favor because it was way more trouble than
simple fixed-bias AB.

I think it mostly fell out of favor because the numbers on the marketing
handouts didn't look as good as a fixed-bias amplifier. You measure the
distortion at full power, where it's highest.

And to the OP: @ 40 wpc, if truly class-A, the thing would be massively heat-sinked,
uncomfortably hot to touch all the time it was on, weight a ton, and you could
easily heat the room (a couple of rooms?) with it.

Pioneer did actually made a class A receiver back in the seventies. It did
indeed weigh a ton and you could heat a room with it.

If you want to swap it out for something more compact, seems like some good
suggestions have been made. But who knows -- you might have a sleeper. Try
"Audiogon" or one of those audio gear sales sites. They might laugh, or
you might find some devotees who really like that model, and its sale would cover
your replacement.

It is a weird world. There is someone out there who will pay a premium for
anything you have, the problem is finding them.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."