Anybody here into tube amps?

[et...@whidbey.com]

Greetings Tubulars,
So I have this crazy idea to build a little tube amp just for fun. The
transformers are quite expensive though. I will be looking for old
ones probably because I can't justify spending loads on new ones. So
considering my almost 60 years old ears, 39 of which have been spent
in noisy environments, and my propensity to listen to loud music, what
should I look for that will sound just a little better than I can
hear? Maybe not an audio xmfr will be OK. There are some old tube amps
in a couple local thrift stores. How can I tell if they had good
xmfrs? Or can I?
Eric

---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

[Martin Eastburn]

So what do you need. Specs ? lots of them about the shop.

Is it power or is it output ?

What is your design look like ? Got the tubes ?

Martin

[jon_banquer]

Tube amps color the music often adding "warmth". I think that's the wrong approach. I believe you want an amp that's transparent / invisible. Tube's are great for instruments but I don't believe they are the right approach for music playback.

http://forums.audioholics.com/forums/amps-pre-pros-receivers/1579-truth-about-tube-amps.html

These were awesome amps but I prefer power hungry speakers and very loud listening levels:

http://www.audiocircle.com/index.php?topic=63956.0

Creator has passed on. Easily some of the cleanest amps I've ever heard. Horribly ugly. Badly marketed. Very high quality.

[PrecisionmachinisT]

<et...@whidbey.com> wrote in message
news:qk6jd95vpjoba184e...@4ax.com...

> Greetings Tubulars,
> So I have this crazy idea to build a little tube amp just for fun. The
> transformers are quite expensive though. I will be looking for old
> ones probably because I can't justify spending loads on new ones. So
> considering my almost 60 years old ears, 39 of which have been spent
> in noisy environments, and my propensity to listen to loud music, what
> should I look for that will sound just a little better than I can
> hear? Maybe not an audio xmfr will be OK. There are some old tube amps
> in a couple local thrift stores. How can I tell if they had good
> xmfrs? Or can I?
> Eric
>

I've built a dozen or so, all point to point wired.

The top quality transformers usually were potted into a square can.

It's important maintain plate-to-plate impedence, so best to use the same
output tubes that the transformers were originally paired with, or at least
look into your tube manual and select a tube a set that is relatively close.

https://www.google.com/search?q=peerless+audio+transformers&source=lnms&tbm=isch&sa=X&ei=mWfbUteYD5HtoASPmYGwDg&ved=0CAkQ_AUoAQ&biw=1173&bih=564


Or you could wind your own...really no reason to use E laminations you have
a lathe...simply trepann out the coil cavity, leaving a "post" in the center
drop in the coils and screw on a round cover to complete the flux gap

[dca...@krl.org]

On Sunday, January 19, 2014 1:05:03 AM UTC-5, PrecisionmachinisT wrote:

>
> Or you could wind your own...really no reason to use E laminations you have
>
> a lathe...simply trepann out the coil cavity, leaving a "post" in the center
>
> drop in the coils and screw on a round cover to complete the flux gap

If you do decide to wind your own, I would recommend using laminations from a power transformer before using a solid chunk of material. Audio transformers use thinner laminations than a power transformer, but ones from a power transformer would be better than solid.

If you want I could keep an eye out for kind of suitable transforms at the local scrap yard. The shipping via a flat rate box would not be too bad. The last heavy stuff I shipped using a flat rate box , got separated from the box. But since then I got some stronger tape.

Dan

[Jim Wilkins]

"PrecisionmachinisT" <precisionm...@notmail.com> wrote in
message news:PNydnddXCtyB9kbP...@scnresearch.com...

>
> Or you could wind your own...really no reason to use E laminations
> you have a lathe...simply trepann out the coil cavity, leaving a
> "post" in the center drop in the coils and screw on a round cover to
> complete the flux gap

This is why transformer cores aren't solid iron:
http://en.wikipedia.org/wiki/Transformer#Laminated_steel_cores
"Early transformer developers soon realized that cores constructed
from solid iron resulted in prohibitive eddy current losses, and their
designs mitigated this effect with cores consisting of bundles of
insulated iron wires."

http://en.wikibooks.org/wiki/Electronics/Transformer_Design

jsw

[Jim Wilkins]

<et...@whidbey.com> wrote in message
news:qk6jd95vpjoba184e...@4ax.com...

> Greetings Tubulars,
> So I have this crazy idea to build a little tube amp just for fun.
> The
> transformers are quite expensive though. I will be looking for old
> ones probably because I can't justify spending loads on new ones. So
> considering my almost 60 years old ears, 39 of which have been spent
> in noisy environments, and my propensity to listen to loud music,
> what
> should I look for that will sound just a little better than I can
> hear?

Better speakers, properly placed.

> Maybe not an audio xmfr will be OK. There are some old tube amps
> in a couple local thrift stores. How can I tell if they had good
> xmfrs? Or can I?
> Eric

http://lenardaudio.com/education/14_valve_amps_5.html


jsw

[Michael A. Terrell]

A large, powdered iron toroid works even better. Like an old 3A
variac. I needed a modulation transformer for a AM mobile radio back in
the '70s. I wound a second winding on a surplus 88 mH telco toroid, and
had excessive audio bandwidth.


--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

[Jim Wilkins]

"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
news:7sKdnb8s78IRZkbP...@earthlink.com...

>
> A large, powdered iron toroid works even better. Like an old 3A
> variac. I needed a modulation transformer for a AM mobile radio
> back in
> the '70s. I wound a second winding on a surplus 88 mH telco toroid,
> and
> had excessive audio bandwidth.

However a coiled sheetmetal 3 Amp Variac core may not work at all. The
response of one I measured fell to nothing above 600Hz.

[PrecisionmachinisT]

"Jim Wilkins" <murat...@gmail.com> wrote in message
news:lbgrjm$r6k$1...@dont-email.me...

Aww okay thanks.

[Michael A. Terrell]

Some are wound, some are powdered iron. The one I had may have been
from a 400 Hz unit.

[Jim Wilkins]

"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message

news:Ttednfm8j-XWlEHP...@earthlink.com...

>
> Jim Wilkins wrote:
>>
>> "Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
>> news:7sKdnb8s78IRZkbP...@earthlink.com...
>> >
>> > A large, powdered iron toroid works even better. Like an old 3A
>> > variac. I needed a modulation transformer for a AM mobile radio
>> > back in the '70s. I wound a second winding on a surplus 88 mH
>> > telco
>> > toroid, and had excessive audio bandwidth.
>>
>> However a coiled sheetmetal 3 Amp Variac core may not work at all.
>> The
>> response of one I measured fell to nothing above 600Hz.
>
>
> Some are wound, some are powdered iron. The one I had may have
> been
> from a 400 Hz unit.

The type that was useless for audio was a General Electric Volt-Pac,
model 9T92A1, 50/60Hz.

[Larry Jaques]

There's that damned Crazy Eddy again...

--
Education is that which remains when one has
forgotten everything he learned in school.
--Albert Einstein

[Jim Wilkins]

"Larry Jaques" <lja...@invalid.diversifycomm.com> wrote in message
news:p06od9p732ensvqbk...@4ax.com...

> On Sun, 19 Jan 2014 10:39:37 -0500, "Jim Wilkins"
> <murat...@gmail.com> wrote:
>
>>"PrecisionmachinisT" <precisionm...@notmail.com> wrote in
>>message news:PNydnddXCtyB9kbP...@scnresearch.com...
>>>
>>> Or you could wind your own...really no reason to use E laminations
>>> you have a lathe...simply trepann out the coil cavity, leaving a
>>> "post" in the center drop in the coils and screw on a round cover
>>> to
>>> complete the flux gap
>>
>>This is why transformer cores aren't solid iron:
>>http://en.wikipedia.org/wiki/Transformer#Laminated_steel_cores
>>"Early transformer developers soon realized that cores constructed
>>from solid iron resulted in prohibitive eddy current losses, and
>>their
>>designs mitigated this effect with cores consisting of bundles of
>>insulated iron wires."
>>
>>http://en.wikibooks.org/wiki/Electronics/Transformer_Design
>
>
> There's that damned Crazy Eddy again...

Not meatloaf again!!

[Larry Jaques]

On Sun, 19 Jan 2014 13:29:10 -0500, "Jim Wilkins"

<murat...@gmail.com> wrote:

>"Larry Jaques" <lja...@invalid.diversifycomm.com> wrote in message
>news:p06od9p732ensvqbk...@4ax.com...
>> On Sun, 19 Jan 2014 10:39:37 -0500, "Jim Wilkins"
>> <murat...@gmail.com> wrote:
>>
>>>"PrecisionmachinisT" <precisionm...@notmail.com> wrote in
>>>message news:PNydnddXCtyB9kbP...@scnresearch.com...
>>>>
>>>> Or you could wind your own...really no reason to use E laminations
>>>> you have a lathe...simply trepann out the coil cavity, leaving a
>>>> "post" in the center drop in the coils and screw on a round cover
>>>> to
>>>> complete the flux gap
>>>
>>>This is why transformer cores aren't solid iron:
>>>http://en.wikipedia.org/wiki/Transformer#Laminated_steel_cores
>>>"Early transformer developers soon realized that cores constructed
>>>from solid iron resulted in prohibitive eddy current losses, and
>>>their
>>>designs mitigated this effect with cores consisting of bundles of
>>>insulated iron wires."
>>>
>>>http://en.wikibooks.org/wiki/Electronics/Transformer_Design
>>
>>
>> There's that damned Crazy Eddy again...
>
>Not meatloaf again!!

I must have gotten a mote in my eye. What did you say?
I don't understand.

[DoN. Nichols]

On 2014-01-19, Michael A. Terrell <mike.t...@earthlink.net> wrote: >
> "dca...@krl.org" wrote:
>>
>> On Sunday, January 19, 2014 1:05:03 AM UTC-5, PrecisionmachinisT wrote:

>> > Or you could wind your own...really no reason to use E laminations
>> > you have a lathe...simply trepann out the coil cavity, leaving a "post"
>> > in the center
>> >
>> > drop in the coils and screw on a round cover to complete the flux
>> > gap

This is sort of like the permanent magnet assembly in at least
one speaker I destroyed as a kid. (Well, the cone was already a goner.)
The center pole and backing plate were one piece (really the pole was
staked into the plate), and the outer housing was a ring Alnico
permanent magnet). Great construction for a stable permanent magnet
field, but not at all good for a transformer.

Now -- for really high frequencies (Ultrasonic, not RF) a
ferrite pot core is really nice. Formed in pretty much the shape
defined above for lathe construction, except that there were two of
them, mounted cup to cup. The cups were available in a large number of
sizes and a number of different ferrite compositions for different
frequency ranges and maximum flux densities.

>> If you do decide to wind your own, I would recommend using
>> laminations from a power transformer before using a solid chunk of
>> material. Audio transformers use thinner laminations than a power
>> transformer, but ones from a power transformer would be better than
>> solid.

Agreed! Thinner laminations are better at higher frequencies.

I do remember some special transformers for really old
telephones which were wound on a core of a number of lengths of straight
iron wire bundled together.

> A large, powdered iron toroid works even better. Like an old 3A
> variac.

Woah! A Variac did *not* use a powedered iron toroid -- nor
did the Superior Electric "Powerstats", nor any other variable
autotransformer by anyone else that I ever saw. :-)

Take a strip of the proper alloy (permalloy? Some other alloy?),
and wind it into a hollow cylinder (with insulating coatings between
layers) and *that* is the toroid that a variable autotransformer is
wound upon. Ideally -- pot that in an insulating material, and use that
to wind the coil on.

Powdered iron (ferrites) are much better at high frequencies,
while most variable autotransformers were optimized for 60 Hz or 50 Hz.
(I have held in my hand some optimized for 400 Hz -- and for those, the
length of the cylinder is about 1/3 that of one for the same current at
60 Hz.

> I needed a modulation transformer for a AM mobile radio back in
> the '70s. I wound a second winding on a surplus 88 mH telco toroid, and
> had excessive audio bandwidth.

:-)

Filtration time. :-)

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: <BPdnic...@d-and-d.com> | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

[PrecisionmachinisT]

"DoN. Nichols" <BPdnic...@d-and-d.com> wrote in message
news:slrnldpcgt.5c...@Katana.d-and-d.com...

> On 2014-01-19, Michael A. Terrell <mike.t...@earthlink.net> wrote: >
>> "dca...@krl.org" wrote:
>>>
>>> On Sunday, January 19, 2014 1:05:03 AM UTC-5, PrecisionmachinisT wrote:
>
>>> > Or you could wind your own...really no reason to use E laminations
>>> > you have a lathe...simply trepann out the coil cavity, leaving a
>>> > "post"
>>> > in the center
>>> >
>>> > drop in the coils and screw on a round cover to complete the flux
>>> > gap
>
> This is sort of like the permanent magnet assembly in at least
> one speaker I destroyed as a kid. (Well, the cone was already a goner.)
> The center pole and backing plate were one piece (really the pole was
> staked into the plate), and the outer housing was a ring Alnico
> permanent magnet). Great construction for a stable permanent magnet
> field, but not at all good for a transformer.
>
> Now -- for really high frequencies (Ultrasonic, not RF) a
> ferrite pot core is really nice. Formed in pretty much the shape
> defined above for lathe construction, except that there were two of

That's what I was referring to, had not realized they were ferrite.

[Michael A. Terrell]

Jim Wilkins wrote:
>
> "Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
> news:Ttednfm8j-XWlEHP...@earthlink.com...
> >
> > Jim Wilkins wrote:
> >>
> >> "Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
> >> news:7sKdnb8s78IRZkbP...@earthlink.com...
> >> >
> >> > A large, powdered iron toroid works even better. Like an old 3A
> >> > variac. I needed a modulation transformer for a AM mobile radio
> >> > back in the '70s. I wound a second winding on a surplus 88 mH
> >> > telco
> >> > toroid, and had excessive audio bandwidth.
> >>
> >> However a coiled sheetmetal 3 Amp Variac core may not work at all.
> >> The
> >> response of one I measured fell to nothing above 600Hz.
> >
> >
> > Some are wound, some are powdered iron. The one I had may have
> > been
> > from a 400 Hz unit.
>
> The type that was useless for audio was a General Electric Volt-Pac,
> model 9T92A1, 50/60Hz.

The cores I'm talking about are the same powdered iron used for power
line filters. I've used a Variac to match a speaker to the speakers on a
factory floor after a fire. No idea what was in the box, it was in the
company's boneyard and in a steel box. There are literally tons of
surplus ferrite cores on Ebay, in almost any shape you can imagine.

[Michael A. Terrell]

"DoN. Nichols" wrote:
>
> On 2014-01-19, Michael A. Terrell <mike.t...@earthlink.net> wrote: >
> > "dca...@krl.org" wrote:
> >>
> >> On Sunday, January 19, 2014 1:05:03 AM UTC-5, PrecisionmachinisT wrote:
>
> >> > Or you could wind your own...really no reason to use E laminations
> >> > you have a lathe...simply trepann out the coil cavity, leaving a "post"
> >> > in the center
> >> >
> >> > drop in the coils and screw on a round cover to complete the flux
> >> > gap
>
> This is sort of like the permanent magnet assembly in at least
> one speaker I destroyed as a kid. (Well, the cone was already a goner.)
> The center pole and backing plate were one piece (really the pole was
> staked into the plate), and the outer housing was a ring Alnico
> permanent magnet). Great construction for a stable permanent magnet
> field, but not at all good for a transformer.

That is because the magnetic bias had the same effect as DC flowing
in the windings. That caused the core to saturate at much lower power
levels.

> Now -- for really high frequencies (Ultrasonic, not RF) a
> ferrite pot core is really nice. Formed in pretty much the shape
> defined above for lathe construction, except that there were two of
> them, mounted cup to cup. The cups were available in a large number of
> sizes and a number of different ferrite compositions for different
> frequency ranges and maximum flux densities.

Pot cores are generally used where the absolute minimum leakage is
allowed.

> >> If you do decide to wind your own, I would recommend using
> >> laminations from a power transformer before using a solid chunk of
> >> material. Audio transformers use thinner laminations than a power
> >> transformer, but ones from a power transformer would be better than
> >> solid.
>
> Agreed! Thinner laminations are better at higher frequencies.
>
> I do remember some special transformers for really old
> telephones which were wound on a core of a number of lengths of straight
> iron wire bundled together.

These were called 'Loading Coils' and were all over the surplus
market in the '70s for pocket change.

> > A large, powdered iron toroid works even better. Like an old 3A
> > variac.
>
> Woah! A Variac did *not* use a powedered iron toroid -- nor
> did the Superior Electric "Powerstats", nor any other variable
> autotransformer by anyone else that I ever saw. :-)

The one I had was salvaged from a damaged, imported 3A unit.

> Take a strip of the proper alloy (permalloy? Some other alloy?),
> and wind it into a hollow cylinder (with insulating coatings between
> layers) and *that* is the toroid that a variable autotransformer is
> wound upon. Ideally -- pot that in an insulating material, and use that
> to wind the coil on.
>
> Powdered iron (ferrites) are much better at high frequencies,
> while most variable autotransformers were optimized for 60 Hz or 50 Hz.
> (I have held in my hand some optimized for 400 Hz -- and for those, the
> length of the cylinder is about 1/3 that of one for the same current at
> 60 Hz.
>
> > I needed a modulation transformer for a AM mobile radio back in
> > the '70s. I wound a second winding on a surplus 88 mH telco toroid, and
> > had excessive audio bandwidth.
>
> :-)
>
> Filtration time. :-)

No, I liked the shocked responses I got from other users. Everyone
else sounded muddy, with their <2K roll off. That radio sounded crisp
and clear after on going through one frequency limiting core than the
usual pair. :)

[Jim Wilkins]

"Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
news:7ImdnS-wXuKbREHP...@earthlink.com...

>
> "DoN. Nichols" wrote:
>>
>> Woah! A Variac did *not* use a powedered iron toroid -- nor
>> did the Superior Electric "Powerstats", nor any other variable
>> autotransformer by anyone else that I ever saw. :-)
>
>
> The one I had was salvaged from a damaged, imported 3A unit.

The OP will waste a lot of time and gasoline finding and testing cores
that don't work well enough.

Do you have the test equipment to measure the frequency response and
distortion of a homebrew transformer at high power levels? You need a
clean sine-wave signal generator and an amp that's better than the one
you are trying to build.

I used a home-made Super Tiger modified into a wideband op amp.
http://www.swtpc.com/mholley/Catalog1969a/Page04.jpg

It was useful as an RF transmitter at Fort Monmouth when the Signal
Corps students started competing to build and run pirate radio
stations and jammers. Electronic surplus was cheap and plentiful in
northern NJ and NYC's Canal Street in 1970 and we learned a lot
through the pranks we concocted.
jsw

[et...@whidbey.com]

On Sat, 18 Jan 2014 22:41:05 -0600, Martin Eastburn
<lion...@consolidated.net> wrote:
Greetings Martin,
I don't have any specs yet. Or a design. I just decided I would like
to do this. 20 watts per channel would be the max output, though I
imagine I will end up with something that puts out much less. I will
amplifying the output of some sort of CD player or mp3 player .
Eric

[et...@whidbey.com]

Winding a transformer like you describe above sounds like fun. There
must be somebody selling the right kind of steel sheet for folks who
want to make their own transformers.

[Jim Wilkins]

<et...@whidbey.com> wrote in message
news:nikqd9lrv3b08vca3...@4ax.com...

> On Sat, 18 Jan 2014 22:41:05 -0600, Martin Eastburn
> <lion...@consolidated.net> wrote:
> Greetings Martin,
> I don't have any specs yet. Or a design. I just decided I would like
> to do this. 20 watts per channel would be the max output, though I
> imagine I will end up with something that puts out much less. I
> will
> amplifying the output of some sort of CD player or mp3 player .
> Eric

The design will be much easier if you use a Class A output like a
radio rather than Class B (push-pull) like a powerful stereo amp.
http://en.wikipedia.org/wiki/Valve_amplifier
See "Topologies".

[Jim Wilkins]

<et...@whidbey.com> wrote in message
news:btkqd95fqigu5oubc...@4ax.com...

>>
> Winding a transformer like you describe above sounds like fun. There
> must be somebody selling the right kind of steel sheet for folks who
> want to make their own transformers.
> Eric

It's vastly easier to recycle an old transformer of adequate core
cross-section for your planned output power. You get the right size of
bobbin to wind your own wire on.
jsw

[Larry Jaques]

Gawd, reaching back to Coleman College in 1987, IIRC, the stuff is
called lamination steel. Low hysteresis + high permeability.
Googlit.


If you get tired of trying to find stuff, here's a 12x12W kit:
http://www.diyaudio.com/forums/siliconray-online-electronics-store/202156-fu-50-12wx2-hifi-tube-amplifier-kit.html

-
To change one's self is sufficient. It's the idiots who want
to change the world who are causing all the trouble.
--Anonymous

[Thanks for all the free stuff -TeaBillies !]

On Friday, January 17, 2014 3:18:36 PM UTC-6, et...@whidbey.com wrote:
> Greetings Tubulars,
>
> So I have this crazy idea to build a little tube amp just for fun. The
>

TedWeber.com

[Michael A. Terrell]

Jim Wilkins wrote:
>
> "Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
> news:7ImdnS-wXuKbREHP...@earthlink.com...
> >
> > "DoN. Nichols" wrote:
> >>
> >> Woah! A Variac did *not* use a powedered iron toroid -- nor
> >> did the Superior Electric "Powerstats", nor any other variable
> >> autotransformer by anyone else that I ever saw. :-)
> >
> >
> > The one I had was salvaged from a damaged, imported 3A unit.
>
> The OP will waste a lot of time and gasoline finding and testing cores
> that don't work well enough.
>
> Do you have the test equipment to measure the frequency response and
> distortion of a homebrew transformer at high power levels? You need a
> clean sine-wave signal generator and an amp that's better than the one
> you are trying to build.

Yes, but my entire shop is covered with plastic sheets till the roof
is replaced. the entire 1200 square foot flat metal roof has to be
removed and replaced.

> I used a home-made Super Tiger modified into a wideband op amp.
> http://www.swtpc.com/mholley/Catalog1969a/Page04.jpg

I built one in that series for the magazine articles in the late
'60s, but I have some high power signal generators like the TS-382F/U
and some high power solid state PA amplifiers. The meter was destroyed
in my HP331A, and I am designing a digital replacement, rather than
scrap another 331/332/333/334 series for the meter.

> It was useful as an RF transmitter at Fort Monmouth when the Signal
> Corps students started competing to build and run pirate radio
> stations and jammers. Electronic surplus was cheap and plentiful in
> northern NJ and NYC's Canal Street in 1970 and we learned a lot
> through the pranks we concocted.

Till they tore it down to build the World Trade Center.

[cl...@snyder.on.ca]

High silicon steel.

[cl...@snyder.on.ca]

look at http://diyaudioprojects.com/Tubes/5751-KT88-Tube-Amp-Kit/.
lots of others out there too.

[cl...@snyder.on.ca]

On Mon, 20 Jan 2014 11:51:08 -0800 (PST), "Thanks for all the free
stuff -TeaBillies !" <loonk...@gmail.com> wrote:

try ax84.com - I think it is still active.

[PrecisionmachinisT]

<et...@whidbey.com> wrote in message
news:btkqd95fqigu5oubc...@4ax.com...

http://www.ebay.com/itm/FISHER-VINTAGE-TUBE-STEREO-CONSOLE-AMPLIFIER-481A-/301074397355?pt=Vintage_Electronics_R2&hash=item46196eb8ab

http://www.ebay.com/itm/Magnavox-Stereo-Tube-Type-Audio-Amplifier-Nice-/380822013397?pt=Vintage_Electronics_R2&hash=item58aac2c5d5

[DoN. Nichols]

On 2014-01-20, Michael A. Terrell <mike.t...@earthlink.net> wrote:
>
> "DoN. Nichols" wrote:
>>
>> On 2014-01-19, Michael A. Terrell <mike.t...@earthlink.net> wrote: >
>> > "dca...@krl.org" wrote:

[ ... ]

>> > A large, powdered iron toroid works even better. Like an old 3A
>> > variac.
>>
>> Woah! A Variac did *not* use a powedered iron toroid -- nor
>> did the Superior Electric "Powerstats", nor any other variable
>> autotransformer by anyone else that I ever saw. :-)
>
>
> The one I had was salvaged from a damaged, imported 3A unit.

Imported -- who knows who made it then, or what modifcations to
the design.

[ ... ]

>> > I needed a modulation transformer for a AM mobile radio back in
>> > the '70s. I wound a second winding on a surplus 88 mH telco toroid, and
>> > had excessive audio bandwidth.
>>
>> :-)
>>
>> Filtration time. :-)
>
>
> No, I liked the shocked responses I got from other users. Everyone
> else sounded muddy, with their <2K roll off. That radio sounded crisp
> and clear after on going through one frequency limiting core than the
> usual pair. :)

Doesn't the FCC get upset if the modulation frequencies push the
bandwidth too far out? Or was it less critical in the '70s?

[Larry Jaques]

On Mon, 20 Jan 2014 15:32:26 -0500, "Michael A. Terrell"
<mike.t...@earthlink.net> wrote:

>
>Jim Wilkins wrote:
>>
>> "Michael A. Terrell" <mike.t...@earthlink.net> wrote in message
>> news:7ImdnS-wXuKbREHP...@earthlink.com...
>> >
>> > "DoN. Nichols" wrote:
>> >>
>> >> Woah! A Variac did *not* use a powedered iron toroid -- nor
>> >> did the Superior Electric "Powerstats", nor any other variable
>> >> autotransformer by anyone else that I ever saw. :-)
>> >
>> >
>> > The one I had was salvaged from a damaged, imported 3A unit.
>>
>> The OP will waste a lot of time and gasoline finding and testing cores
>> that don't work well enough.
>>
>> Do you have the test equipment to measure the frequency response and
>> distortion of a homebrew transformer at high power levels? You need a
>> clean sine-wave signal generator and an amp that's better than the one
>> you are trying to build.
>
>
> Yes, but my entire shop is covered with plastic sheets till the roof
>is replaced. the entire 1200 square foot flat metal roof has to be
>removed and replaced.

Write a letter to Obama. Maybe he'll give you a grant. ;)

>> It was useful as an RF transmitter at Fort Monmouth when the Signal
>> Corps students started competing to build and run pirate radio
>> stations and jammers. Electronic surplus was cheap and plentiful in
>> northern NJ and NYC's Canal Street in 1970 and we learned a lot
>> through the pranks we concocted.
>
>
> Till they tore it down to build the World Trade Center.

Suckage!

[Gunner Asch]

On Mon, 20 Jan 2014 22:35:32 -0800, Larry Jaques
<lja...@invalid.diversifycomm.com> wrote:

>>
>>
>> Yes, but my entire shop is covered with plastic sheets till the roof
>>is replaced. the entire 1200 square foot flat metal roof has to be
>>removed and replaced.
>
>Write a letter to Obama. Maybe he'll give you a grant. ;)

Mikes a veteran. Id suggest not mentioning that, else the IRS and the
ATF will have one of their SWAT teams busting down his front door.

Tell Obama he is a ardent Democrat who has dreams of doing electronics
work to "help Mankind and the DNC" and they will build him a brand new
bright and shiney industrial area of his very own.

Gunner

__
"Anyone who thinks Obama is doing a good job
is either stupid or a perpetual societal leech"

[Michael A. Terrell]

"DoN. Nichols" wrote:
>
> On 2014-01-20, Michael A. Terrell <mike.t...@earthlink.net> wrote:
> >
> > "DoN. Nichols" wrote:
> >>
> >> On 2014-01-19, Michael A. Terrell <mike.t...@earthlink.net> wrote: >
> >> > "dca...@krl.org" wrote:
>
> [ ... ]
>
> >> > A large, powdered iron toroid works even better. Like an old 3A
> >> > variac.
> >>
> >> Woah! A Variac did *not* use a powedered iron toroid -- nor
> >> did the Superior Electric "Powerstats", nor any other variable
> >> autotransformer by anyone else that I ever saw. :-)
> >
> >
> > The one I had was salvaged from a damaged, imported 3A unit.
>
> Imported -- who knows who made it then, or what modifcations to
> the design.

It had to be powdered iron made for low frequency work. I've used a
standard variac to match an amp to speakers, and some PA volume controls
are tapped autotransformers.


If he wants to try winding a transformer, small APC UPS have a nice
laminated core, and scrap units are around for free. I currently have
about 25 with bad batteries.

> >
> > No, I liked the shocked responses I got from other users. Everyone
> > else sounded muddy, with their <2K roll off. That radio sounded crisp
> > and clear after on going through one frequency limiting core than the
> > usual pair. :)
>
> Doesn't the FCC get upset if the modulation frequencies push the
> bandwidth too far out? Or was it less critical in the '70s?

The FCC would have to catch someone using that radio. Since it was
mainly used to listen, it didn't matter. The only downside was that you
could hear some adjacent channel crap as high pitch noise if the
transmitter was close enough. That radio didn't use ceramic IF filters.

[et...@whidbey.com]

On Sun, 19 Jan 2014 06:05:37 -0800 (PST), "dca...@krl.org"

<dca...@krl.org> wrote:

>On Sunday, January 19, 2014 1:05:03 AM UTC-5, PrecisionmachinisT wrote:
>
>>

>> Or you could wind your own...really no reason to use E laminations you have
>>
>> a lathe...simply trepann out the coil cavity, leaving a "post" in the center
>>
>> drop in the coils and screw on a round cover to complete the flux gap
>

>If you do decide to wind your own, I would recommend using laminations from a power transformer before using a solid chunk of material. Audio transformers use thinner laminations than a power transformer, but ones from a power transformer would be better than solid.
>

>If you want I could keep an eye out for kind of suitable transforms at the local scrap yard. The shipping via a flat rate box would not be too bad. The last heavy stuff I shipped using a flat rate box , got separated from the box. But since then I got some stronger tape.
>
> Dan
Greetings Dan,
If I decide to wind my own laminations I'll let you know. Thanks for
the offer. My local scrap yard is good but I cannot recall seeing and
xmfrs there.
Eric

[pyotr filipivich]

Gunner Asch <gunne...@gmail.com> on Tue, 21 Jan 2014 00:21:49 -0800
typed in rec.crafts.metalworking the following:

>On Mon, 20 Jan 2014 22:35:32 -0800, Larry Jaques
><lja...@invalid.diversifycomm.com> wrote:
>
>>>
>>>
>>> Yes, but my entire shop is covered with plastic sheets till the roof
>>>is replaced. the entire 1200 square foot flat metal roof has to be
>>>removed and replaced.
>>
>>Write a letter to Obama. Maybe he'll give you a grant. ;)
>
>Mikes a veteran. Id suggest not mentioning that, else the IRS and the
>ATF will have one of their SWAT teams busting down his front door.
>
>Tell Obama he is a ardent Democrat who has dreams of doing electronics
>work to "help Mankind and the DNC" and they will build him a brand new
>bright and shiney industrial area of his very own.

Just be sure to mention that it will be environmentally friendly
and "forward thinking".
--
pyotr filipivich
"With Age comes Wisdom. Although more often, Age travels alone."

[Gunner Asch]

Which reminds me..I stopped in a 7-11 this afternoon for a tube steak
and some cookies and in the parking lot was a guy sitting in his car
surrounded by his worldly goods in a halfway decent car..with a faded
but still clearly read Obama/Biden sticker on the back of his trunk.

He was sitting there sucking on a beer looking rather morose and as I
got into my truck..I nodded and asked "hows that hopey/changey thingy
working out for you"

He started to puff up and then shut his face rather quickly. I simply
smiled again, fired up and drove off.

Damn that felt good.

[Larry Jaques]

On Sat, 25 Jan 2014 06:51:33 -0800, Gunner Asch <gunne...@gmail.com>
wrote:

TWO POINTS! ROTFLMAO.

--
Sound character provides the power with which a person may ride
the emergencies of life instead of being overwhelmed by them.
Failure is... the highway to success.
--Og Mandino

[Jon Banquer]

In article <u148e9hucpdmmp7rb...@4ax.com>,
lja...@invalid.diversifycomm.com says...

Larry Jackass gets it wrong again. It's the same two points that idiots
like Mark Wieber and Larry Jackass can't comprehend:


Mark Wieber lives on junk food.

Mark Wieber's next heart attack treatment will once again be paid for by
taxpayers just like it was last time.

[Spehro Pefhany]

On Fri, 17 Jan 2014 13:18:36 -0800, the renowned et...@whidbey.com
wrote:

>Greetings Tubulars,
>So I have this crazy idea to build a little tube amp just for fun. The
>transformers are quite expensive though. I will be looking for old
>ones probably because I can't justify spending loads on new ones. So
>considering my almost 60 years old ears, 39 of which have been spent
>in noisy environments, and my propensity to listen to loud music, what
>should I look for that will sound just a little better than I can
>hear? Maybe not an audio xmfr will be OK. There are some old tube amps
>in a couple local thrift stores. How can I tell if they had good
>xmfrs? Or can I?
>Eric

If you ever run across something from McIntosh, in almost any
condition, that would be a good bet.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
sp...@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

[et...@whidbey.com]

On Mon, 27 Jan 2014 08:32:25 -0500, Spehro Pefhany
<spef...@interlogDOTyou.knowwhat> wrote:

>On Fri, 17 Jan 2014 13:18:36 -0800, the renowned et...@whidbey.com
>wrote:
>
>>Greetings Tubulars,
>>So I have this crazy idea to build a little tube amp just for fun. The
>>transformers are quite expensive though. I will be looking for old
>>ones probably because I can't justify spending loads on new ones. So
>>considering my almost 60 years old ears, 39 of which have been spent
>>in noisy environments, and my propensity to listen to loud music, what
>>should I look for that will sound just a little better than I can
>>hear? Maybe not an audio xmfr will be OK. There are some old tube amps
>>in a couple local thrift stores. How can I tell if they had good
>>xmfrs? Or can I?
>>Eric
>
>If you ever run across something from McIntosh, in almost any
>condition, that would be a good bet.
>
>
>Best regards,
>Spehro Pefhany

So I could either re-build the old McIntosh or just use the
transformers and any good tubes to build my own? Probably rebuilding
would be best, and I bet there are schematics available online.
Thanks,
Eric

[Martin Eastburn]

Mostly it is the electrolytic caps that dry out. Some are power
and some are Bias or bypass / blockers - filters of all types.

Foil and mica don't go bad unless really high voltage is generated.

Good idea. Most tubes last and last.

Martin

[Gunner Asch]

On Mon, 27 Jan 2014 08:32:25 -0500, Spehro Pefhany
<spef...@interlogDOTyou.knowwhat> wrote:

>On Fri, 17 Jan 2014 13:18:36 -0800, the renowned et...@whidbey.com
>wrote:
>
>>Greetings Tubulars,
>>So I have this crazy idea to build a little tube amp just for fun. The
>>transformers are quite expensive though. I will be looking for old
>>ones probably because I can't justify spending loads on new ones. So
>>considering my almost 60 years old ears, 39 of which have been spent
>>in noisy environments, and my propensity to listen to loud music, what
>>should I look for that will sound just a little better than I can
>>hear? Maybe not an audio xmfr will be OK. There are some old tube amps
>>in a couple local thrift stores. How can I tell if they had good
>>xmfrs? Or can I?
>>Eric
>
>If you ever run across something from McIntosh, in almost any
>condition, that would be a good bet.
>
>
>Best regards,
>Spehro Pefhany

Call this friend of mine..and be SURE to drop my name...

http://www.manta.com/c/mmdz56p/p-t-engineering

He has gone into the vintage sound business and has shitloads of tube
amps/tuners etc etce etc.

He buys stuff, fills a cargo container..and ships it to the rich
people in Vietnam. Granted they are communists..but they do indeed
have money to piss away.

Tell him in general what you are looking for and give him the top of
your price range..he will find you something.

Gunner

__
"Anyone who thinks Obama is doing a good job
is either stupid or a perpetual societal leech"