Why the high price for tube amps?

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade? I have
and use electric motors that are over 50m years old and their windings
don't suffer from bad insulation. I even have old magnetos on old
tractors that work perfectly and the insulation in them must be pretty
stressed because of the high voltage.
Thanks,
Eric

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[Kaz Kylheku]

On 2014-01-16, etpm@whidbey.com <etpm@whidbey.com> wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive.

Tube gear is expensive because buyers expect it to be and sellers get whatever
they can.

People don't buy tube gear for entirely rational reasons in the first place,
and many buyers of tube stuff can be easly counted upon to fall into this
category.

People who don't do things for entirely rational reasons can also be
relied upon not to spend entirely rational sums of money.

Some tube gear is true vintage gear and so its price is jacked up like that
of any other antique. There is demand for the item, not a lot of it around,
and they stopped making it fifty years ago.

Non-tube vintage gear is the same way. Some old synthesizers from the early
80's still fetch surprising prices. I just googled "Yamaha DX7" "Craigslist"
and the first hit wants a whopping $275 US. For the same $$$, you can get
a synth that was made after Y2K, but for some buyers, that would be
the "it" they are looking for.

Newly produced tube gear which is "like" that vintage gear receives a kind of
rub off effect from this, like faux antique furniture that is expensive, though
nothing special.

If someone made a faithful re-issue clone of that Yamaha DX7, they'd want an arm
and a leg for it, you can be sure.

 

[Michael Black]

On Thu, 16 Jan 2014, etpm@whidbey.com wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade? I have
and use electric motors that are over 50m years old and their windings
don't suffer from bad insulation. I even have old magnetos on old
tractors that work perfectly and the insulation in them must be pretty
stressed because of the high voltage.

Transformers are frequency limiting devices. You can design them for wide
response, but it will cost you. For instance, a 400Hz transformer will be
fine for voice (there was a time when there was plenty of 400Hz
transformers from airplane use so people would use them to build
modulators for AM transmitters), but woudlnt' do well reproducing lower
freuqencies. A 60Hz transformer would reproduce those lower frequencies,
but might not do so well at higher frequencies.

So unless you start with a decent amplifier, you may find the transformers
limiting. Tube audio amplifiers were the norm for decades, there is
nothing magical about them. They can be cheap and used for PA use, or
they can be expensive and used for extreme HiFi, or somewhere in between.

If they are cheap they will be a limiting factor. If they arent' cheap,
then there wont' be a lot in the amplifier that is limiting.

You can always use bigger coupling capacitors and bypass capacitors,
improve the power supply filters, but if the coupling transformers are
inferior, the amp will be inferior.

One difference between solid state and tube amplifiers is that the
transformers are eliminated. Different topology brought about by solid
state being low impedance while tubes are high impedance. You actually
see that, early audio amplifiers were designed like tube amplifiers,
complete with output transformers, maybe even coupling transformers
between stages. But soon the shift was done, the full value of the
transistors put into use, and the transformers gone. Which mean
amplifiers that were lot flatter than a lot of the previous tube
amplifiers.

Transformers generally don't fail by themselves, they fail because of
overload.

Michael

 

[Tim Wescott]

On Thu, 16 Jan 2014 12:49:51 -0800, etpm wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive and
many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be bad.
Do the transformers go bad? Does the insulation degrade? I have and use
electric motors that are over 50m years old and their windings don't
suffer from bad insulation. I even have old magnetos on old tractors
that work perfectly and the insulation in them must be pretty stressed
because of the high voltage.

Tube amplifier quality is determined quite a bit by the transformer. If
you can find an old tube high fidelity amplifier in a thrift store, then
yes, you could rip out the transformers and make your own and hope that
it would sound good.

If you find some crappy old dime-store radio in thrift store, then you're
probably not going to get much better than crappy old dime-store radio
sound in your amplifier.

All consumer expectations aside, tube transformers are boutique items
that need a lot of expensive metal for the windings and the core, and are
being consumed at low volumes. Even if they were selling 100,000 units a
year, you'd still have to pay for the copper and the iron. Since they
ain't selling 100,000 units a year, you're also paying a stiff premium to
buy a low-production item.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Phil Allison]

<etpm@whidbey.com>

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade?

** The first tube ( aka valve) amp put together was made entirety from
scavenged parts.

Two 6V6s and a 5Y3 from old radios and a war surplus 6SN7 twin triode.

The output transformer was an AC supply transformer taken from another
radio, the centre tapped HT winding did for the tube anodes and the 5V and
6.3V heater windings wired in series did for the 8 ohm output.

An 8 inch "electrodynamic" speaker provided sound and a filter coke for the
HT.

Not really hi-fi - but sounded wonderful to me.


...... Phil

 

[asdf]

etpm@whidbey.com wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.

Mosfet amps get the best of two worlds IMO: they sound very close or
identical to tubes and can be really easy to build. Not to mention
they're a lot cheaper.
They don't glow unfortunately, but something can be done about that
http://www.youtube.com/watch?v=ekuqOaRbp8g

 

On Thu, 16 Jan 2014 23:41:07 -0600, Tim Wescott
<tim@seemywebsite.really> wrote:

On Thu, 16 Jan 2014 12:49:51 -0800, etpm wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive and
many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be bad.
Do the transformers go bad? Does the insulation degrade? I have and use
electric motors that are over 50m years old and their windings don't
suffer from bad insulation. I even have old magnetos on old tractors
that work perfectly and the insulation in them must be pretty stressed
because of the high voltage.

Tube amplifier quality is determined quite a bit by the transformer. If
you can find an old tube high fidelity amplifier in a thrift store, then
yes, you could rip out the transformers and make your own and hope that
it would sound good.

If you find some crappy old dime-store radio in thrift store, then you're
probably not going to get much better than crappy old dime-store radio
sound in your amplifier.

All consumer expectations aside, tube transformers are boutique items
that need a lot of expensive metal for the windings and the core, and are
being consumed at low volumes. Even if they were selling 100,000 units a
year, you'd still have to pay for the copper and the iron. Since they
ain't selling 100,000 units a year, you're also paying a stiff premium to
buy a low-production item.

Greetings Tim,
I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I
mainly want to see how one I make sounds.
Eric

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[Tim Wescott]

On Fri, 17 Jan 2014 09:53:54 -0800, etpm wrote:

On Thu, 16 Jan 2014 23:41:07 -0600, Tim Wescott
tim@seemywebsite.really> wrote:

On Thu, 16 Jan 2014 12:49:51 -0800, etpm wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade? I have
and use electric motors that are over 50m years old and their windings
don't suffer from bad insulation. I even have old magnetos on old
tractors that work perfectly and the insulation in them must be pretty
stressed because of the high voltage.

Tube amplifier quality is determined quite a bit by the transformer. If
you can find an old tube high fidelity amplifier in a thrift store, then
yes, you could rip out the transformers and make your own and hope that
it would sound good.

If you find some crappy old dime-store radio in thrift store, then
you're probably not going to get much better than crappy old dime-store
radio sound in your amplifier.

All consumer expectations aside, tube transformers are boutique items
that need a lot of expensive metal for the windings and the core, and
are being consumed at low volumes. Even if they were selling 100,000
units a year, you'd still have to pay for the copper and the iron.
Since they ain't selling 100,000 units a year, you're also paying a
stiff premium to buy a low-production item.
Greetings Tim,
I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound a
tube amp would look cool on the shelf with all the glow. But I mainly
want to see how one I make sounds.

The only way I know would be to make sure that the thrift store amplifier
was pretty damned good to begin with.

There's a pretty marked correlation between quality and expense to an
audio transformer, and always has been. Not very many people would have
built cheezy equipment with really good transformers.

The only other possible way that I can think of would be to hook up with
an old-time audiophile who happens to know if there were any brands or
models whose transformers were better than the rest of the amp.

But I just don't think that you're going to hit the "audiophile"
threshold in a thrift-store tube amp, if you could even find something in
a thrift store with tubes. You may hit paydirt at an estate sale, or
finding something on eBay that's trashed but has good output
transformers, but I just don't think the local Goodwill is going to be
your friend, here.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[amdx]

On 1/17/2014 11:53 AM, etpm@whidbey.com wrote:

But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I
mainly want to see how one I make sounds.
Eric

I don't know anything about tubes, but you may need to pick the
proper tube for your transformer or vise versa.
Take a look at these Ebay listings just to get an idea what is
available, and prices.

http://www.ebay.com/sch/i.html?_trksid=m570.l3201&_nkw=audio+output+transformer&_sacat=0
Mikek

 

[Michael Black]

On Fri, 17 Jan 2014, Tim Wescott wrote:

But I just don't think that you're going to hit the "audiophile"
threshold in a thrift-store tube amp, if you could even find something in
a thrift store with tubes. You may hit paydirt at an estate sale, or
finding something on eBay that's trashed but has good output
transformers, but I just don't think the local Goodwill is going to be
your friend, here.

I think this is true. I see lots of junk at garage sales, but an "antique
radio" or even that 1950s shortwaver receiver I got for $20 are pretty
uncommon. Tube stuff has either been tossed a long time ago, or is now
landing in dedicated circles. For that matter, I gather some places like
Goodwill may be presorting, so if they ended up with a good tube
amplifier, it may be sold through some other venue.

That's the nature of it. Something gets old, it becomes cheap, but few
people want it. Then some time later, nostalgia kicks in, at about the
same time scarcity becomes an issue. So the price goes up for what's
still available. The time when people dropped stuff off at charity groups
to get rid of it is long passed.

Michael

 

[Michael Black]

On Fri, 17 Jan 2014, etpm@whidbey.com wrote:

I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I
mainly want to see how one I make sounds.
Eric

It's not absolute, but the bigger the transformer the better.

Look at a cheap All American 5 radio, the transformers aren't much bigger
than you'd see in transistor radios (when transistor radios had
transformers in the audio chain). They have to be limited in their
ability to reproduce lower frequencies. A good amplifier from the tube
age would have vastly bigger transformers.

Think about speakers. A tiny 2" speaker in a transistor radio has no
bass, can't handle power, may not even be so good at handling high
frequenies. Good speakers will be much bigger, and with a nice hefty
magnet. It really is the same thing, since both the transformers and the
speakers have to handle the full range of sound and the full power output,
and are doing it at a low impedance (well the secondary of the output
transformer).

Interstage coupling transformers can be much smaller because they are
operating at high impedance, a very low current situation.

Go with Phil's idea, build the amplifier with plenty of space for output
transformers, and until you find some good ones (hence the space for their
eventual placement) use power output transformers. Not hifi, but it gives
you practice.

Michael

 

On Fri, 17 Jan 2014 12:07:02 -0600, Tim Wescott
<tim@seemywebsite.really> wrote:

On Fri, 17 Jan 2014 09:53:54 -0800, etpm wrote:

On Thu, 16 Jan 2014 23:41:07 -0600, Tim Wescott
tim@seemywebsite.really> wrote:

On Thu, 16 Jan 2014 12:49:51 -0800, etpm wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade? I have
and use electric motors that are over 50m years old and their windings
don't suffer from bad insulation. I even have old magnetos on old
tractors that work perfectly and the insulation in them must be pretty
stressed because of the high voltage.

Tube amplifier quality is determined quite a bit by the transformer. If
you can find an old tube high fidelity amplifier in a thrift store, then
yes, you could rip out the transformers and make your own and hope that
it would sound good.

If you find some crappy old dime-store radio in thrift store, then
you're probably not going to get much better than crappy old dime-store
radio sound in your amplifier.

All consumer expectations aside, tube transformers are boutique items
that need a lot of expensive metal for the windings and the core, and
are being consumed at low volumes. Even if they were selling 100,000
units a year, you'd still have to pay for the copper and the iron.
Since they ain't selling 100,000 units a year, you're also paying a
stiff premium to buy a low-production item.
Greetings Tim,
I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound a
tube amp would look cool on the shelf with all the glow. But I mainly
want to see how one I make sounds.

The only way I know would be to make sure that the thrift store amplifier
was pretty damned good to begin with.

There's a pretty marked correlation between quality and expense to an
audio transformer, and always has been. Not very many people would have
built cheezy equipment with really good transformers.

The only other possible way that I can think of would be to hook up with
an old-time audiophile who happens to know if there were any brands or
models whose transformers were better than the rest of the amp.

But I just don't think that you're going to hit the "audiophile"
threshold in a thrift-store tube amp, if you could even find something in
a thrift store with tubes. You may hit paydirt at an estate sale, or
finding something on eBay that's trashed but has good output
transformers, but I just don't think the local Goodwill is going to be
your friend, here.

The reason I mentioned thrift stores is because I do see old tube
amps and radios for sale pretty cheap ikn thrift stores around where I
live. There is even a recording phonograph for sale in a local thrift
store. It has two arms. One for playback and the other for recording.
It even has mike on a cord. I don't know where to find discs for the
thing to record on though.
Eric

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[Jim Thompson]

On Fri, 17 Jan 2014 09:53:54 -0800, etpm@whidbey.com wrote:

On Thu, 16 Jan 2014 23:41:07 -0600, Tim Wescott
tim@seemywebsite.really> wrote:

On Thu, 16 Jan 2014 12:49:51 -0800, etpm wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive and
many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be bad.
Do the transformers go bad? Does the insulation degrade? I have and use
electric motors that are over 50m years old and their windings don't
suffer from bad insulation. I even have old magnetos on old tractors
that work perfectly and the insulation in them must be pretty stressed
because of the high voltage.

Tube amplifier quality is determined quite a bit by the transformer. If
you can find an old tube high fidelity amplifier in a thrift store, then
yes, you could rip out the transformers and make your own and hope that
it would sound good.

If you find some crappy old dime-store radio in thrift store, then you're
probably not going to get much better than crappy old dime-store radio
sound in your amplifier.

All consumer expectations aside, tube transformers are boutique items
that need a lot of expensive metal for the windings and the core, and are
being consumed at low volumes. Even if they were selling 100,000 units a
year, you'd still have to pay for the copper and the iron. Since they
ain't selling 100,000 units a year, you're also paying a stiff premium to
buy a low-production item.
Greetings Tim,
I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I
mainly want to see how one I make sounds.
Eric

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http://www.avast.com

Transformer quality is by-the-pound ;-)

When I built toooob stuff, the transformers were "two-hands" worth.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Tim Wescott]

On Fri, 17 Jan 2014 13:58:46 -0500, Michael Black wrote:

On Fri, 17 Jan 2014, etpm@whidbey.com wrote:


I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I mainly
want to see how one I make sounds.
Eric

It's not absolute, but the bigger the transformer the better.

Look at a cheap All American 5 radio, the transformers aren't much
bigger than you'd see in transistor radios (when transistor radios had
transformers in the audio chain). They have to be limited in their
ability to reproduce lower frequencies. A good amplifier from the tube
age would have vastly bigger transformers.

Think about speakers. A tiny 2" speaker in a transistor radio has no
bass, can't handle power, may not even be so good at handling high
frequenies. Good speakers will be much bigger, and with a nice hefty
magnet. It really is the same thing, since both the transformers and the
speakers have to handle the full range of sound and the full power
output,
and are doing it at a low impedance (well the secondary of the output
transformer).

Interstage coupling transformers can be much smaller because they are
operating at high impedance, a very low current situation.

Go with Phil's idea, build the amplifier with plenty of space for output
transformers, and until you find some good ones (hence the space for
their eventual placement) use power output transformers. Not hifi, but
it gives you practice.

If you can't find power transformers, or if you're married to the idea of
"audio" transformers, look at tube guitar amp output transformers.

They're mass-marked (well, kinda), won't sound terribly bad, and the
price is nice for lower power kit.

I've been kicking around the idea of a 15W/channel toob amp for my PC
speakers, using guitar amp output trannys sitting on a chassis with
enough space for the nice Hammond ones that Antique Radio Supply sells.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Jim Thompson]

On Fri, 17 Jan 2014 13:53:27 -0600, Tim Wescott
<tim@seemywebsite.really> wrote:

On Fri, 17 Jan 2014 13:58:46 -0500, Michael Black wrote:

On Fri, 17 Jan 2014, etpm@whidbey.com wrote:


I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I mainly
want to see how one I make sounds.
Eric

It's not absolute, but the bigger the transformer the better.

Look at a cheap All American 5 radio, the transformers aren't much
bigger than you'd see in transistor radios (when transistor radios had
transformers in the audio chain). They have to be limited in their
ability to reproduce lower frequencies. A good amplifier from the tube
age would have vastly bigger transformers.

Think about speakers. A tiny 2" speaker in a transistor radio has no
bass, can't handle power, may not even be so good at handling high
frequenies. Good speakers will be much bigger, and with a nice hefty
magnet. It really is the same thing, since both the transformers and the
speakers have to handle the full range of sound and the full power
output,
and are doing it at a low impedance (well the secondary of the output
transformer).

Interstage coupling transformers can be much smaller because they are
operating at high impedance, a very low current situation.

Go with Phil's idea, build the amplifier with plenty of space for output
transformers, and until you find some good ones (hence the space for
their eventual placement) use power output transformers. Not hifi, but
it gives you practice.

If you can't find power transformers, or if you're married to the idea of
"audio" transformers, look at tube guitar amp output transformers.

They're mass-marked (well, kinda), won't sound terribly bad, and the
price is nice for lower power kit.

I've been kicking around the idea of a 15W/channel toob amp for my PC
speakers, using guitar amp output trannys sitting on a chassis with
enough space for the nice Hammond ones that Antique Radio Supply sells.

I grew up on toooobs, switched to transistors, enjoyed _damping_,
never looked back.

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jasen Betts]

On 2014-01-17, Michael Black <et472@ncf.ca> wrote:

On Fri, 17 Jan 2014, etpm@whidbey.com wrote:


I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound
a tube amp would look cool on the shelf with all the glow. But I
mainly want to see how one I make sounds.
Eric


Go with Phil's idea, build the amplifier with plenty of space for output
transformers, and until you find some good ones (hence the space for their
eventual placement) use power output transformers. Not hifi, but it gives
you practice.

Yeah, Phil previously remarked that modern strip-wound power toroids work
supprisingly well in the audio band, so that's possibly a better (and
easier) option than re-purposing an old toob power transformer.

--
For a good time: install ntp

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[John Fields]

On Thu, 16 Jan 2014 12:49:51 -0800, etpm@whidbey.com wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.

---
Take a look at the audio power amps starting on page 694:

http://www.tubebooks.org/tubedata/RC30.pdf

JF

 

[John Fields]

On Fri, 17 Jan 2014 11:42:07 -0800, etpm@whidbey.com wrote:

On Fri, 17 Jan 2014 12:07:02 -0600, Tim Wescott
tim@seemywebsite.really> wrote:

On Fri, 17 Jan 2014 09:53:54 -0800, etpm wrote:

On Thu, 16 Jan 2014 23:41:07 -0600, Tim Wescott
tim@seemywebsite.really> wrote:

On Thu, 16 Jan 2014 12:49:51 -0800, etpm wrote:

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade? I have
and use electric motors that are over 50m years old and their windings
don't suffer from bad insulation. I even have old magnetos on old
tractors that work perfectly and the insulation in them must be pretty
stressed because of the high voltage.

Tube amplifier quality is determined quite a bit by the transformer. If
you can find an old tube high fidelity amplifier in a thrift store, then
yes, you could rip out the transformers and make your own and hope that
it would sound good.

If you find some crappy old dime-store radio in thrift store, then
you're probably not going to get much better than crappy old dime-store
radio sound in your amplifier.

All consumer expectations aside, tube transformers are boutique items
that need a lot of expensive metal for the windings and the core, and
are being consumed at low volumes. Even if they were selling 100,000
units a year, you'd still have to pay for the copper and the iron.
Since they ain't selling 100,000 units a year, you're also paying a
stiff premium to buy a low-production item.
Greetings Tim,
I understand about the boutique status of the amps and why this raises
the price of the kits, tubes, and completed units. But I didn't know
that the xmfrs were so special. Is there a simple way to tell if the
xmfrs in a thrift store unit are any good? I suppose I could look for
specific brand names. But is there any other way? Aside from the sound a
tube amp would look cool on the shelf with all the glow. But I mainly
want to see how one I make sounds.

The only way I know would be to make sure that the thrift store amplifier
was pretty damned good to begin with.

There's a pretty marked correlation between quality and expense to an
audio transformer, and always has been. Not very many people would have
built cheezy equipment with really good transformers.

The only other possible way that I can think of would be to hook up with
an old-time audiophile who happens to know if there were any brands or
models whose transformers were better than the rest of the amp.

But I just don't think that you're going to hit the "audiophile"
threshold in a thrift-store tube amp, if you could even find something in
a thrift store with tubes. You may hit paydirt at an estate sale, or
finding something on eBay that's trashed but has good output
transformers, but I just don't think the local Goodwill is going to be
your friend, here.
The reason I mentioned thrift stores is because I do see old tube
amps and radios for sale pretty cheap ikn thrift stores around where I
live. There is even a recording phonograph for sale in a local thrift
store. It has two arms. One for playback and the other for recording.
It even has mike on a cord. I don't know where to find discs for the
thing to record on though.

---
Google "transcription disc"

 

[petrus bitbyter]

<etpm@whidbey.com> schreef in bericht
news:buggd9tguuf4pk8dlosdd4df9vn85abfmd@4ax.com...

I have been thinking about making a tube amp for fun so I can compare
the sound to a good solid state amp and because I like making things.
I remember with fondness the sound from my old tube amps years ago.
But it could be that my memory is flawed. Anyway, I looked at kits and
they are all very expensive. Tubes themselves are not that expensive
and many amps that get good reviews only have a couple tubes.
Transformers are really expensive. Are the transformers used for tube
amps really that special? What if I just buy an old amp from a thrift
store and replace the tubes and any other components that might be
bad. Do the transformers go bad? Does the insulation degrade? I have
and use electric motors that are over 50m years old and their windings
don't suffer from bad insulation. I even have old magnetos on old
tractors that work perfectly and the insulation in them must be pretty
stressed because of the high voltage.
Thanks,
Eric

---
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protection is active.
http://www.avast.com

Good tubes never were cheap. A good set of matched EL34 for instance can do
a $50,- and you need two set for a stereo amp.

The real expensive parts are the output transformers. Good transformers
always were expensive and they still are. But where the quality of tubes
degrades (cheap Russian and Chinese production) and there has not been any
development for decades, transformers stil became better over the years and
much more expensive. They can easily do a $150,- a piece. Still cheap
compared to types with silver plated wire. Some people say they hear the
difference.

So if you find a good tube amplifier you'd best try to restore it. Otherwise
you may use the power supply and the output transformers to build you own
one. Real good amps (matched tubes, ring core transformers) can be bought
over here for a E1000,- though I doubt *I* will hear the difference between
that one and a E500,- type.

petrus bitbyter

 

[Jim Thompson]

On Fri, 17 Jan 2014 23:23:45 +0100, "petrus bitbyter"
<petrus.bitbyter@hotmail.com> wrote:

Good tubes never were cheap. A good set of matched EL34 for instance can do
a $50,- and you need two set for a stereo amp.

Not when I was a kid, IIRC ~$8 ;-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
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I love to cook with wine. Sometimes I even put it in the food.