J
[email protected]
- Jan 1, 1970
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Wow, this is a REAL AMPLIFIER !!!!
- Thread starter [email protected]
- Start date
J
Joerg
- Jan 1, 1970
- 0
John said:
Or you wind a new coil for the speaker. Done it once but never, ever
again. I think that was the episode where I used more cusswords than all
the rest of my life. It was a huge speaker from a circus that had folded
and I needed it to get to a few hundred ohms.
Guy plugged in his E-guitar ... *TWWWAAAIIINGGGG* ... thwok ...
darkness. The 230V/16A breaker had popped.
I guess one could also buy a boatload of small speakers and string them
in series but I didn't have that kind of money as a student. The added
risk with my amp was that there could be up 900V riding on the speaker
coil so nobody was allowed anywhere near it. I am still amazed it didn't
arc over because back then I didn't pay much attention to dielectric
properties and stuff.
J
[email protected]
- Jan 1, 1970
- 0
I was wondering where they get the transformers??????
They must be custom made and very costly. The power transformers
might be made for large transmitters, but the output xformers almost
have to be custom made.
Just curious why the HF response would be poor? Is that due to the
thickness of the insulation in the xformer?
Now, if I was building this, there would eight output tubes instead of
four. Putting out over 2000 watts, and four (quad) channels.
Over 8000 watts would make a kick ass stereo (quad) sound system. Of
course there is no point in having that much power, but I like to
dream about excessive shit like this.
I recall reading somewhere that the Woodstock Festival had a 10,000
watt sound system. So my 8000 watt amps could liven up many acres of
land and probably get me arrested for excessive noise
J
Joerg
- Jan 1, 1970
- 0
Typically one would buy them used and rewind them if necessary:
http://www.ebay.com/itm/TWO-UMX-300...439366?cmd=ViewItem&pt=Vintage_Electronics_R2
It's actually not poor at all. I was mighty surprised when I had to test
some aircraft designs here, so I needed a stiff power source up to
440Hz. Vary the frequency, apply nasty surges, the works. Generator ->
big Kenwood amp -> ordinary 60Hz line transformer. After completing the
tests I became curious. Now how high would it go? To my surprise this
60Hz transformer easily did several kHz without the core heating up
much. And above a few kHz you don't really need much power for audio
purposes.
However, back when I built my amp there was no Ebay and I couldn't even
buy a kilowatt-sized mains transformer. Those cost too much. So I
generated slightly over 900VDC from 230VAC, Cockroft-Walton style. In a
country where wall outlets where not keyed and you could plug them both
ways. Woe to those who didn't measure first and plugged in the "wrong"
way ... -> Hint to readers: DO NOT do this! (I was young and foolish
back then).
[...]
J
Jamie
- Jan 1, 1970
- 0
I have some 4-1000Z tubes around here. Some new, some
only used a little.
Maybe I should Ebay them. I don't think I'll be
doing much with them in my life time but I wonder what
kind of an audio amp they would make?
I got these from a place where they used them in EDM machines
to operate the quill at 400hz. I also have a supply and output
transformer..
Jamie
J
Joerg
- Jan 1, 1970
- 0
John said:
Not really. Tube amps can have remarkable frequency response and when
you are dealing with kilowatt-range stuff the impedances are not very
high. Just a few hundred Ohms. It take lots of capacitance to mess with
that.
The trick was to massively parallel color TV flyback driver tubes.
That's how I built my first one. They run really nicely between 600V and
900V. IIRC my 930V was a bit over the limit but they hung on. Later I
built an RF amp the same way (copied someone else's published plan
though) but in order to remain legal I had to back off to five tubes.
J
Jamie
- Jan 1, 1970
- 0
Oh yeah, used to make CB amplifiers out of them in my younger days, somePhil said:
where mobile
Jamie
J
Joerg
- Jan 1, 1970
- 0
Yes, PL509. The really old PL36 from the early 60's B/W sets was very
good as well but harder to find. Surprisingly my RF amp had better
linearity than some expensive commercial ones with the big tubes. The
audio version before that, I don't know. That was more like a highschool
buddy competition and only power output mattered. The music back then,
Jefferson Airplane or Led Zeppelin, didn't sound particularly linear
anyhow
Oooh ... a friend did that but they caught him. What really did him in
wasn't the big amp per se but the fact that he had a police crystal in
his rig. So they took it all away from him. "Otherwise we'd just have
taken the amplifier", they said.
good as well but harder to find. Surprisingly my RF amp had better
linearity than some expensive commercial ones with the big tubes. The
audio version before that, I don't know. That was more like a highschool
buddy competition and only power output mattered. The music back then,
Jefferson Airplane or Led Zeppelin, didn't sound particularly linear
anyhow
Oh yeah, used to make CB amplifiers out of them in my younger days, some
where mobile
Oooh ... a friend did that but they caught him. What really did him in
wasn't the big amp per se but the fact that he had a police crystal in
his rig. So they took it all away from him. "Otherwise we'd just have
taken the amplifier", they said.
M
Mr.CRC
- Jan 1, 1970
- 0
but at max 50KHz pwm I doubt it will do full audio range
frequencies
something like this: http://www.cadaudio.dk/d2404asw.pdf
2400W@4R 20-20KHz, 9.8" x 6" x 1.8" with power supply
list price 309euro ...
I did a 0-10kHz 72V 9A cont./15Apk class-D servo amp with Apex parts and
some help from folks here.
No way to get that thing over 10kHz BW. Well, maybe it would be
possible if I ever get to understanding the z-transform...
It bugs me though, that it's usually a choice of DC to a few kHz, or AC
coupled audio amps that go to 20kHz or better, but without the ability
to configure in current mode and configure with DC coupling.
R
Ralph Barone
- Jan 1, 1970
- 0
D from BC said:
Max switching frequency 50 kHz. That's not gonna cut it for broad band
audio applications, although it would make a hell of a subwoofer amp.
J
John Taylor
- Jan 1, 1970
- 0
What about the amplifiers that modulated the carrier of a 50kW AM
transmitter ? 25 kW at less than 3% distortion.
Exception to the RCA Ampliphase that didn't have transformers. Flat to
20kH at less than 1% distortion. Like an FM transmitter.
T
Tauno Voipio
- Jan 1, 1970
- 0
EL500, EL504 and EL509. They put plenty of oomph with 600 V on anodes,
and many could be run as zero-bias triodes by paralleling grid and
screen. The grids needed some resistors to ptotect them from excessive
dissipation from the drive.
I have also built one audio amplifier with a pair of 813's, but it
was for modulating two other 813's.
T
Tauno Voipio
- Jan 1, 1970
- 0
You'd need a bank of 10 each side to get a kilowatt.
813 is an order of magnitude sturdier than 807.
If you do not need the WW2 look of the tubes,
6146 would be a better substitute to 807.
R
Rich Grise
- Jan 1, 1970
- 0
Don't use 813's, if you want some REAL POWER!
http://w5jgv.com/4-400A_600M_amplifier/4-400A.pdf
Cheers!
Rich
R
Ralph Barone
- Jan 1, 1970
- 0
Rich Grise said:
Glass envelope, air cooled, tungsten anode... Amateur.
Try this
http://www.cpii.com/docs/datasheets/78/4CM2500KG June 2011.pdf
T
Tauno Voipio
- Jan 1, 1970
- 0
There are larger bottles in the same line: 4-1000A,
or triodes: 3-500Z, 3-1000Z.
R
Rich Grise
- Jan 1, 1970
- 0
John said:
Neat. 10 kilowatts for the filament alone.
But audiophools would prefer glass, so they can see the stuff glowing
inside.
[/QUOTE]
4-400As are especially kewl when the plate glows cherry-red.
Cheers!
Rich
J
Joerg
- Jan 1, 1970
- 0
Tauno said:
For ham radio we've used PL509 because the TV-version was much cheaper
and they had that coveted formal 30W plate dissipation rating. It also
allowed us to feed five filaments in series. Since that was 40V each we
could connect one PL500 (used to regulate the grid 2) in series as well
and got an almost perfect match to 230V.
[...]
U
[email protected]
- Jan 1, 1970
- 0
If you can get over 100 A anode current through a vacuum tube, this is
quite extraordinary. For a mercury filled tube that is not too
spectacular.
R
Ralph Barone
- Jan 1, 1970
- 0
John Larkin said:
Given the rated plate voltage, I think it would be wise to have as much
metal as I could fit between the possible X-ray source and my head.
