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Message |
Bob
Guest
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 Posted:
Fri Nov 04, 2005 5:31 am Post subject:
Toroid power in guitar amp |
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Can anyone think of a reason NOT to use a toroid power transformer in a small
guitar amp?
I'm thinking it will eliminate the hum field coming from most typical combos, so
the guitarist can sit on it and not worry about his single coil guitar picking
up hum.
Looks like I'll need 2, one for the PS and one for the filaments.
Any ideas welcome.
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Bob
Guest
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| Posted:
Fri Nov 04, 2005 5:44 am Post subject:
Re: Toroid power in guitar amp |
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On Fri, 4 Nov 2005 15:53:09 +1100, "Phil Allison" <philallison@tpg.com.au>
wrote:
| Quote: |
"Bob"
So you think I won't get any advantage ..
** You said "eliminate".
Goal posts need to stay put.
.......... Phil
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Sorry Phil, I realized later I didn't include enough info.
I take it therefore you mean there would be some advantage, but of course the
field wouldn't be eliminated.
I appreciated the time you take to answer my questions, thanks again. |
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Phil Allison
Guest
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| Posted:
Fri Nov 04, 2005 5:44 am Post subject:
Re: Toroid power in guitar amp |
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"Bob"
| Quote: | So you think I won't get any advantage ..
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** You said "eliminate".
Goal posts need to stay put.
........... Phil |
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Bob
Guest
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| Posted:
Fri Nov 04, 2005 5:44 am Post subject:
Re: Toroid power in guitar amp |
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On Fri, 4 Nov 2005 11:11:17 +1100, "Phil Allison" <philallison@tpg.com.au>
wrote:
| Quote: |
"Bob"
Can anyone think of a reason NOT to use a toroid power transformer in a
small
guitar amp?
** Behringer do.
I'm thinking it will eliminate the hum field coming from most typical
combos, so
the guitarist can sit on it and not worry about his single coil guitar
picking
up hum.
** No it won't.
The low external field claims of toroid makers are based on resistive load
conditions.
........ Phil
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So you think I won't get any advantage with a small class A amp running an EL84
in class A? I wouldn't think there would be a big power factor there. Maybe it
would be a good marketing tool!!
Thanks for your comments. |
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Phil Allison
Guest
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| Posted:
Fri Nov 04, 2005 5:44 am Post subject:
Re: Toroid power in guitar amp |
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"Bob"
| Quote: |
Can anyone think of a reason NOT to use a toroid power transformer in a
small
guitar amp?
|
** Behringer do.
| Quote: | I'm thinking it will eliminate the hum field coming from most typical
combos, so
the guitarist can sit on it and not worry about his single coil guitar
picking
up hum.
|
** No it won't.
The low external field claims of toroid makers are based on resistive load
conditions.
......... Phil |
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Lord Valve
Guest
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| Posted:
Fri Nov 04, 2005 2:22 pm Post subject:
Re: Toroid power in guitar amp |
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Bob wrote:
| Quote: | Can anyone think of a reason NOT to use a toroid power transformer in a small
guitar amp?
I'm thinking it will eliminate the hum field coming from most typical combos, so
the guitarist can sit on it and not worry about his single coil guitar picking
up hum.
Looks like I'll need 2, one for the PS and one for the filaments.
Any ideas welcome.
|
Egnaters use 'em.
LV |
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Pooh Bear
Guest
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| Posted:
Fri Nov 04, 2005 3:53 pm Post subject:
Re: Toroid power in guitar amp |
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Bob wrote:
| Quote: | Can anyone think of a reason NOT to use a toroid power transformer in a small
guitar amp?
I'm thinking it will eliminate the hum field coming from most typical combos, so
the guitarist can sit on it and not worry about his single coil guitar picking
up hum.
Looks like I'll need 2, one for the PS and one for the filaments.
Any ideas welcome.
|
Toroids simply have *lower* radiated field than most other transformers. It won't
'eliminate' anything.
The lowest radiated flux is from O-core transformers btw.
Graham |
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Alexius
Guest
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| Posted:
Fri Nov 04, 2005 3:54 pm Post subject:
Re: Toroid power in guitar amp |
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Bob wrote:
| Quote: | Can anyone think of a reason NOT to use a toroid power transformer in a small
guitar amp?
I'm thinking it will eliminate the hum field coming from most typical combos, so
the guitarist can sit on it and not worry about his single coil guitar picking
up hum.
Looks like I'll need 2, one for the PS and one for the filaments.
Any ideas welcome.
If you know how to fix it, and if the toroid is O.K., don't worry... |
Toroid transformer have much less waste magnetic field, but you must
know how to fix it without "one wind more". I mean, it is hard to fix
firmly, with only one center screw. If you use more screws it has
behavior lake one wind more from center to outside, and again to chasis...
www.alex.com.hr |
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Alexius
Guest
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| Posted:
Fri Nov 04, 2005 3:58 pm Post subject:
Re: Toroid power in guitar amp |
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Pooh Bear wrote:
| Quote: |
Bob wrote:
Can anyone think of a reason NOT to use a toroid power transformer in a small
guitar amp?
I'm thinking it will eliminate the hum field coming from most typical combos, so
the guitarist can sit on it and not worry about his single coil guitar picking
up hum.
Looks like I'll need 2, one for the PS and one for the filaments.
Any ideas welcome.
Toroids simply have *lower* radiated field than most other transformers. It won't
'eliminate' anything.
The lowest radiated flux is from O-core transformers btw.
Graham
That's not quite true. Transformer would not "eliminate" anything, but |
it's radiation is enough for sensitive pickups (especially single
coil)wich is capable for radio broadcast recieving..
www.alex.com.hr |
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Bret Ludwig
Guest
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| Posted:
Sat Nov 05, 2005 3:11 am Post subject:
Re: Toroid power in guitar amp |
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Bend up a simple metal bracket (you do have a sheet metal brake?) and
affix it with a plastic bolt and nut. Go to a car dealer parts counter
and ask for a plastic bolt and nut. Most cars use them somewhere. |
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Fred
Guest
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| Posted:
Sat Nov 05, 2005 5:43 am Post subject:
Re: Toroid power in guitar amp |
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"Bob" <BobFlintsTone@spam.com> wrote
| Quote: | On 4 Nov 2005 13:11:16 -0800, "Bret Ludwig" <bretldwig@yahoo.com> wrote:
Bend up a simple metal bracket (you do have a sheet metal brake?)
yes, but I was thinking of using a large washer... any problem with mounting it
between metals? I could always find a large plastic washer if so... and I do
have some nylon hardware...
and
affix it with a plastic bolt and nut. Go to a car dealer parts counter
and ask for a plastic bolt and nut. Most cars use them somewhere.
|
You don't need plastic hardware; plastic hardware will almost certainly fail the first
time the amp tips over. Usually toroids are mounted between rubber washers (to
protect the windings) with a formed metal washer on top and a chassis underneath,
secured by a steel bolt and nut. The only thing you need to avoid is a conductive path
through the center of the donut that goes around the outside and back to the center.
That would act as a shorted secondary turn which would get very hot very quickly,
possibly causing the release of the precious magic smoke that makes these things
work in the first place. Getting the magic smoke back into a transformer is much
more difficult than getting escaped toothpaste back into its tube. ;-)
The rubber washers and formed metal washers are available from the companies that
make the toroids, and from their distributers.
Fred |
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Phil Allison
Guest
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| Posted:
Sat Nov 05, 2005 5:43 am Post subject:
Re: Toroid power in guitar amp |
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"Ian Iveson"
| Quote: | You should ensure that both transformers are adequately specified so they
don't saturate.
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** Huh ??
What pig ignorant drivel.
........... Phil |
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Bob
Guest
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| Posted:
Sat Nov 05, 2005 5:43 am Post subject:
Re: Toroid power in guitar amp |
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On Sat, 05 Nov 2005 04:36:09 GMT, "Ian Iveson" <IanIveson.home@blueyonder.co.uk>
wrote:
| Quote: | Bob wrote
Bend up a simple metal bracket (you do have a sheet metal brake?)
yes, but I was thinking of using a large washer... any problem
with mounting it
between metals? I could always find a large plastic washer if
so... and I do
have some nylon hardware...
Large washers and rubber or dense foam pads seem to be pretty
standard...toroids usually come with a mounting kit. As long as the
clamping load is spread evenly and the mounting doesn't form a
conductive winding.
|
I want to try out the new series of Hammond toroids... not sure how they come...
I ordered a few today to play with...
I wonder if I can negate the fields more if I mount the 2 trannys on top of each
other, oriented for cancellation...
| Quote: | You should ensure that both transformers are adequately specified so
they don't saturate.
|
I ordered a 6v @ 2.5 amp for the filaments and a 234v @ 128ma for the plate
supply, I plan on using a bridge for a 3 watt EL84 amp, with 2 - 12AX7a tubes.
I'll be happy if I get 250 VDC. I'm way over spec 'ed!
| Quote: | You may wish to add series resistance on the HT
secondary to provide some sag...depends on what you have in mind. I
believe toroids are best used with full-wave rectification BTW. I
wonder what kind of rectification Egnaters use?
|
I might play around with a full wave doubler to see what I get... maybe make
something a bit bigger... maybe even a P-P EL84 18 watter with a 234v @ 214ma...
It's winter building season! |
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Ian Iveson
Guest
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| Posted:
Sat Nov 05, 2005 5:43 am Post subject:
Re: Toroid power in guitar amp |
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Bob wrote
| Quote: |
Bend up a simple metal bracket (you do have a sheet metal brake?)
yes, but I was thinking of using a large washer... any problem
with mounting it
between metals? I could always find a large plastic washer if
so... and I do
have some nylon hardware...
|
Large washers and rubber or dense foam pads seem to be pretty
standard...toroids usually come with a mounting kit. As long as the
clamping load is spread evenly and the mounting doesn't form a
conductive winding.
You should ensure that both transformers are adequately specified so
they don't saturate. You may wish to add series resistance on the HT
secondary to provide some sag...depends on what you have in mind. I
believe toroids are best used with full-wave rectification BTW. I
wonder what kind of rectification Egnaters use?
Am I the last champion here of the wonderful
http://www.duncanamps.com/
home of the excellent power supply design software
http://www.duncanamps.com/psud2/index.html
which is free!
Also several forums, loads of design stuff, circuits, and of course
the centre of the known universe:
http://tdsl.duncanamps.com/tubesearch.php
Not to mention the equally tremendous and free
http://www.duncanamps.com/tdslpe/index.html
cheers, Ian |
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Bob
Guest
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| Posted:
Sat Nov 05, 2005 5:43 am Post subject:
Re: Toroid power in guitar amp |
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On 4 Nov 2005 13:11:16 -0800, "Bret Ludwig" <bretldwig@yahoo.com> wrote:
| Quote: | Bend up a simple metal bracket (you do have a sheet metal brake?)
|
yes, but I was thinking of using a large washer... any problem with mounting it
between metals? I could always find a large plastic washer if so... and I do
have some nylon hardware...
| Quote: | and
affix it with a plastic bolt and nut. Go to a car dealer parts counter
and ask for a plastic bolt and nut. Most cars use them somewhere. |
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