Hi
I had a quick look on the guitar amp group but decided to post there.
Thought this a more appropriate site.
I just watched an amp I fancied go through the roof (finacially) on ebay.
Here's the schematic:-
http://www.blueguitar.org/new/schem/...n/sndn_a50.gif.
Not sure why I liked it, think it was the two channels and a govenor, gov on
the diag' that drops the sound levels whilst keeping the tube distortion.
I do have a vague grasp of such things as 400V not harming but 30mA can
kill. ex electronics.
All I know about valves is "they get hot".
If I price up the project and go for it can anyone mentor me? Or is the info
on that diagram too lacking?
If you live in England I could stretch to a bottle or two of malt.
Ah yes England, need to adapt to readily available valves etc.
Any imput appreciated
Ian

B Bear wrote:

Hi
I had a quick look on the guitar amp group but decided to post there.
Thought this a more appropriate site.
I just watched an amp I fancied go through the roof (finacially) on ebay.
Here's the schematic:-
http://www.blueguitar.org/new/schem/...n/sndn_a50.gif.
Not sure why I liked it, think it was the two channels and a govenor, gov on
the diag' that drops the sound levels whilst keeping the tube distortion.
I do have a vague grasp of such things as 400V not harming but 30mA can
kill. ex electronics.
All I know about valves is "they get hot".
If I price up the project and go for it can anyone mentor me? Or is the info
on that diagram too lacking?
If you live in England I could stretch to a bottle or two of malt.
Ah yes England, need to adapt to readily available valves etc.
Any imput appreciated
Ian





What sort of bear is this? :- )

The "gov" merely shunts across the grids (drive) to the P-P output
stage. Not sure that this will have the desired effect, especially if
that "gov" pot can be turned all the way to a "short" - which it
apparently can... but yes, if you reduce the drive to the final tube,
then you can turn up the gain to the input or along the way and achieve
clipping (distortion). No magic here. You can use this little bit on any
schematic that has capacitively coupled drive to the grids.

My advice, is pick a schematic of an amp that you already know you like
the sound of. (Is this one of the amps that Clapton uses? Sundown??)

The second bit of advice, is don't even consider trying this sort of
thing if you have no experience building electronics - not until you
know something more. Too complex, and requires all sorts of specialized
parts, tools and test gear.

Third bit, the parts will cost you more than you expect, AND, it won't
sound like you expect - the sound will be all over the map depending on
parts chosen and tubes and minor deviations in values.

Fourth bit, try to buy an amp from some bloke who has smoked it beyond
repair, and repair it. At least that way you'll get a large part of the
thing, especially the chassis already there - hopefully all you'll need
to do is to replace one or both transformers, some tubes, and maybe a
cap and/or resistor or two. After that you can "mod" it until it looks
like the amp you're interested in now if you should like.

Fifth bit, learn how power amps and preamp circuits work a little bit
and dork with some simple stuff in isolation to build your experience
before tackling a large and complex project.

Both hi-fi (of any type and size) tube gear and guitar tube gear (even 5
watt practice amps) are extremely similar in design - good places to
learn with inexpensive stuff. Like an old tube console with a record
player in it, for example. Makes a nifty guitar practice amp, and
electronics practice test bed.

:_ )

_-_-bear


http://www.bearlabs.com

Many thanks for that. Had a quick peek in Maplin and yes the cost went up
very fast!
I am toying with the idea of getting a defunked amp. As you say at least
that should be able to be got going reasonably easily.
FYI ex electronics. But back n the days when resistors were bigger than a
piece of dandruff.
One problem is everything on ebay is going through the roof nowadays.
Cheers me dears.
BB
"BEAR" wrote in message
...
B Bear wrote:

Hi
I had a quick look on the guitar amp group but decided to post there.
Thought this a more appropriate site.
I just watched an amp I fancied go through the roof (finacially) on ebay.
Here's the schematic:-
http://www.blueguitar.org/new/schem/...n/sndn_a50.gif.
Not sure why I liked it, think it was the two channels and a govenor, gov
on the diag' that drops the sound levels whilst keeping the tube
distortion.
I do have a vague grasp of such things as 400V not harming but 30mA can
kill. ex electronics.
All I know about valves is "they get hot".
If I price up the project and go for it can anyone mentor me? Or is the
info on that diagram too lacking?
If you live in England I could stretch to a bottle or two of malt.
Ah yes England, need to adapt to readily available valves etc.
Any imput appreciated
Ian





What sort of bear is this? :- )

The "gov" merely shunts across the grids (drive) to the P-P output stage.
Not sure that this will have the desired effect, especially if that "gov"
pot can be turned all the way to a "short" - which it apparently can...
but yes, if you reduce the drive to the final tube, then you can turn up
the gain to the input or along the way and achieve clipping (distortion).
No magic here. You can use this little bit on any schematic that has
capacitively coupled drive to the grids.

My advice, is pick a schematic of an amp that you already know you like
the sound of. (Is this one of the amps that Clapton uses? Sundown??)

The second bit of advice, is don't even consider trying this sort of thing
if you have no experience building electronics - not until you know
something more. Too complex, and requires all sorts of specialized parts,
tools and test gear.

Third bit, the parts will cost you more than you expect, AND, it won't
sound like you expect - the sound will be all over the map depending on
parts chosen and tubes and minor deviations in values.

Fourth bit, try to buy an amp from some bloke who has smoked it beyond
repair, and repair it. At least that way you'll get a large part of the
thing, especially the chassis already there - hopefully all you'll need to
do is to replace one or both transformers, some tubes, and maybe a cap
and/or resistor or two. After that you can "mod" it until it looks like
the amp you're interested in now if you should like.

Fifth bit, learn how power amps and preamp circuits work a little bit and
dork with some simple stuff in isolation to build your experience before
tackling a large and complex project.

Both hi-fi (of any type and size) tube gear and guitar tube gear (even 5
watt practice amps) are extremely similar in design - good places to learn
with inexpensive stuff. Like an old tube console with a record player in
it, for example. Makes a nifty guitar practice amp, and electronics
practice test bed.

:_ )

_-_-bear


http://www.bearlabs.com

"B Bear" said:

One problem is everything on ebay is going through the roof nowadays.
Cheers me dears.


Try visiting hamfests, prices there are very reasonable (at least in
my little corner of the world).
Stereo EL84 amps for ‚¬50, 807s and 6L6GCs gor ‚¬5, etc.

--

"Audio as a serious hobby is going down the tubes."
- Howard Ferstler, 25/4/2005

B Bear wrote:

Many thanks for that. Had a quick peek in Maplin and yes the cost went up
very fast!
I am toying with the idea of getting a defunked amp. As you say at least
that should be able to be got going reasonably easily.

Try to "bear" in mind that you are talking to sophisticated audio
experts and pioneers about a tube guitar amp, which is hardly
engineered at all and was/is largely developed by breaking rules and
flying by the seat of the pants with only the creation of interesting
or useful guitar tones in mind, and enough life to last until the next
model came out. The most famous and still-desired (by many) guitar
amps were thrown together at the lowest practical cost using cheap
parts with some musical & electrical experimentation by people who were
more like electronic mechanics trying to make a big buck in a highly
competitive new market than engineers, and were marketed to learn what
configurations sold best & came back for the least $$ claims. It is
much like the sidewalk artist cranking out watercolors until s/he locks
into what the highest number of tourists will pay for this year, versus
the high-end graphics designer who knows exactly what he is doing & how
to get there from beginning to end in a narrowly focussed fashion and
with no (or very few) compromises.

Try not to mix the two together, and you will do fine with very little
money. Many of the early factory guitar amps are far worse than almost
anything you could build today unless you tried to under-do them, and
there are still many tons of tube audio junk around everywhere (except
on the day you are looking).

I have posted many caveats about the selection & use of salvaged old
tube amp parts (particularly iron) in silk purse/sow's ear homebrew
smaller guitar amps that can save you some pitfalls. You may google
them up on the AGA newsgroup. All of us have had our ugly junkbuild
guitar amp days behind us - I won a state battle of the bands with one
in 1967 against guys with thousands of dollars of new gear (and parted
it back out it shortly thereafter, it was a real rush/cobble job & ugly
as sin). There is no reason you cannot do better with all that we have
laying around today.

Also, while wishing no insult to the emminent designer/builder above,
the notion that a larger tube guitar amp is "complex" is flawed.
Please review my long recent post in the above area about self-building
in general, which may be in the FAQ's by now. Unless you are just
bored and want something to mess around soldering, you should only
build what you want to play and keep that meets your needs, and all
traditional tube guitar amps are very simple circuit-wise and
otherwise. The very first one I built from scratch was a 60w PP 807
(long prior the above amp) that kicked butt, it was built in a cellar
with only 5 tools & no test equipment except a homemade voltmeter, it
took me 4 days including school & my boyhood chores, nothing was new
except the chassis, resistors & MIL surplus tubes, and if you want to
there is no reason you cannot & should not do the same if it pleases
you. I played at least 50 gigs with that amp, fixed many broken
Fenders while it kept working (they were not very reliable then), and
eventually paid for a good car with the proceeds (we could drive at
15). I am still building guitar amps, and IM46yrNSHO&E, internet
advice is not the way to do it and is not part of the solution, but a
big part of the problem.

Your assessment leaves out a lot of history.

When early guitar amps were designed, the idea that they were "tone
producers", except in the vaguest sense, was not there. The combo
guitar amp was also a steel guitar amp, an accordion amp, and for all
intents and purpose a house PA also. It was a cheap and convenient
alternative to buying a small mixer and power amp or modular PA system,
looked swank, easily portable with minimal cabling and hookup. No one
wanted speciific kinds of distortion or overdrive, because no one
selling or building them wanted that at all.

Guitar amps were designed for the most power and least distortion
available for the least amount of money, just like PA amps, radios,
portable record players, and console stereos. Reverb and tremolo were
built in for convenience later, along with "tone controls" which were
treble and bass rolloffs, i.e. crude EQ. They used off the shelf power
transformers, tubes, resistors, caps, and output transformers which
were "utility grade". The output sections of most guitar amps were in
fact better designed from a fidelity standpoint than most console
stereos and portable record players. Designs in both cases were usually
largely cookbooked from tube and transformer manuals.

Hamfests and scrapped stereos of less than prime quality are still
possible sources of parts, but one can now buy everything new at very
reasonable prices when adjusted for inflation if one will set up a
paper company and do business with musical instrument sources at the
store discount, which is sometimes 50%-the "A mark".

wrote:
Your assessment leaves out a lot of history.

When early guitar amps were designed, the idea that they were "tone
producers", except in the vaguest sense, was not there. The combo
guitar amp was also a steel guitar amp, an accordion amp, and for all
intents and purpose a house PA also. It was a cheap and convenient
alternative to buying a small mixer and power amp or modular PA system,
looked swank, easily portable with minimal cabling and hookup. No one
wanted speciific kinds of distortion or overdrive, because no one
selling or building them wanted that at all.

Guitar amps were designed for the most power and least distortion
available for the least amount of money, just like PA amps, radios,
portable record players, and console stereos. Reverb and tremolo were
built in for convenience later, along with "tone controls" which were
treble and bass rolloffs, i.e. crude EQ. They used off the shelf power
transformers, tubes, resistors, caps, and output transformers which
were "utility grade". The output sections of most guitar amps were in
fact better designed from a fidelity standpoint than most console
stereos and portable record players. Designs in both cases were usually
largely cookbooked from tube and transformer manuals.

Hamfests and scrapped stereos of less than prime quality are still
possible sources of parts, but one can now buy everything new at very
reasonable prices when adjusted for inflation if one will set up a
paper company and do business with musical instrument sources at the
store discount, which is sometimes 50%-the "A mark".

So, how is that new job selling shoes going?

This attempt at whatever it was went over my head pretty well. Do shoe
stores have 50% markup as well?

Er down boys!
Thanks for all the FB. I'm going down the route of picking up an amp and if
necessary moding it.
Have to be realistic as to whether I'd ever finish the job and having priced
the components it's not worth it. No not a new one!
The 50% sounds the same as fishing tackle mark up. I take it you may be US
residents in which case bear in mind that when you pay dollars we pay
pounds. i.e a $500 rod costs £500 pounds. Basically we get ripped off. This
means that the cost of things, amps in this case, is higher over here so
anything going gets snapped up. Just look on ebay. (one exception being
vintage gear).
I've heard of people who buy from overseas. Cut a deal on what is put as the
value of the goods to avoid duty. That way they have something for less than
half the price here.
Cheers me dears.
Right off to learn that third chord.
BB

----- Original Message -----
From:
Newsgroups: rec.audio.tubes
Sent: Monday, July 11, 2005 10:43 PM
Subject: guitar amps


This attempt at whatever it was went over my head pretty well. Do shoe
stores have 50% markup as well?


wrote in message
ups.com...
This attempt at whatever it was went over my head pretty well. Do shoe
stores have 50% markup as well?