[[email protected]]

Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

[thomas]

On Feb 3, 4:09 pm, wrote:
Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.

[[email protected]]

On Feb 3, 4:42 pm, "thomas" wrote:
On Feb 3, 4:09 pm, wrote:

Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?
Thank you. Reusing old chassis is an interesting thought.


Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.

[[email protected]]

On Feb 3, 3:46 pm, "Bret Ludwig" wrote:
On Feb 3, 4:09 pm, wrote: Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Sowter in England or Lars Lundahl in Sweden are the transformer
vendors I've been recommending but Heyboer in the US is now doing a
couple of Peerless designs, at a much better price than the fraud Mike
LeFevre, and the quality has to be better hands down.

Bending up your own chassis is a necessary part of paying dues. You
can use found objects with a little metalwork as well.

The ST70 is no good? I have no idea.

What kind of circuits are better for beginners? SE or PP?

Thank you.

Martin

I disrecommend toroids for outputs and of course, if you like being
"the catcher" for rough butt sex that's your business buit if so
there's Magnequeef.

Use new production tubes when starting out. Or tubes still cheap
surplus.

The ST70 is worth about two hundred and fifty bucks if you can get a
kit for that, all new parts including an uprated power transformer.
The stock circuit is NO ****ING GOOD, but you can easily substitute
better.

A power amp isn't really the best first project but what else do
people want to build out of tubes anymore?

[robert casey]

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.


Wow. I had a machine like this back in the 70's. Long since gone. The
tubes were compactrons (the 6T9's) and it was built on a circuit board.
The usual crappy phenolic boards you find in consumer products.
Though the transformers (if I recall correctly) were mounted on the
chassis. There were also large and long record/play switches mounted on
the circuit board. If you wanted to use the circuit board, you could
remove these switches and solder in wire jumpers to make it always in
playback mode. Or else you'll need to buy some new compactron sockets.

[thomas]

On Feb 3, 11:45 pm, "Bret Ludwig" wrote:
On Feb 3, 6:42 pm, "thomas" wrote:





On Feb 3, 4:09 pm, wrote:

Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.

First off, telling beginners to junk things out is a Bad idea.

Is it a Good Idea? Well, considering that he's getting Fender Champ
level output transformers that are 40+ years old, no. Maybe not even
that good.

These kind of amps are so far from high fidelity they should be taken
to the range and used for .50 BMG targets yet gullies pay good money
for homebrew amps like this.- Hide quoted text -

- Show quoted text -

I assume that the goal of a beginner's project is to learn how to
build, not to make the ultimate amp. Better to risk destroying cheap
junk than risk destroying valuable parts IMO.

[Jon Yaeger]

in article ,
at wrote on 2/3/07 10:12 PM:

On Feb 3, 4:42 pm, "thomas" wrote:
On Feb 3, 4:09 pm, wrote:

Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?
Thank you. Reusing old chassis is an interesting thought.


Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.




Why reuse when you can have a new custom chassis?

Www.yaegeraudio.com

Jon

[Jon Yaeger]

in article , thomas at
wrote on 2/3/07 7:42 PM:

On Feb 3, 4:09 pm, wrote:
Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.





Drat. One of my "secrets" is out of the box.

One other Wollensak uses 7591s in class A with 6EU7 drivers.

I recycle the 7591s in higher wattage products, but the remaining iron makes
an awesome headphone amplifier (I have a .pdf of one I built if anyone
wants it). And the assembly has a shock-mounted 9 pin socket that is great
for minimizing microphonics in a preamp.

Jon

[John Byrns]

In article . com,
"Bret Ludwig" wrote:

Sowter in England or Lars Lundahl in Sweden are the transformer
vendors I've been recommending but Heyboer in the US is now doing a
couple of Peerless designs, at a much better price than the fraud Mike
LeFevre, and the quality has to be better hands down.

Bending up your own chassis is a necessary part of paying dues. You
can use found objects with a little metalwork as well.

The ST70 is no good? I have no idea.

What kind of circuits are better for beginners? SE or PP?

Thank you.

Martin

Single ended amps are simpler to build but you won't learn very much
for them and they sound, in general, pretty lame.

I don't agree, while the active circuits in a PP amp are marginally more
complex than in a SE amplifier, the power supply for a SE amp is far
more complex, requiring one or more inductors to get the hum down to
reasonable levels. The output transformers are also larger and heavier
for equivalent power output and low frequency response. It simply takes
a lot more iron to build a decent SE amp as compared with a PP amp of
similar power.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[robert casey]

Single ended amps are simpler to build but you won't learn very much
for them and they sound, in general, pretty lame.


Some people prefer single ended amps.

In any event, what the OP and other beginners would need is something
that's not expensive, easily built, but will still sound better than the
standard issue solid state amps you can buy at WalMart. Into speakers
that also came from WalMart.

[west]

"Jon Yaeger" wrote in message
...
in article ,
at wrote on 2/3/07 10:12 PM:

On Feb 3, 4:42 pm, "thomas" wrote:
On Feb 3, 4:09 pm, wrote:

Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?
Thank you. Reusing old chassis is an interesting thought.


Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.




Why reuse when you can have a new custom chassis?

Www.yaegeraudio.com

Jon

Jon ... Do you give a Rodent discount?

west

[west]

"Bret Ludwig" wrote in message
ups.com...

Sowter in England or Lars Lundahl in Sweden are the transformer
vendors I've been recommending but Heyboer in the US is now doing a
couple of Peerless designs, at a much better price than the fraud Mike
LeFevre, and the quality has to be better hands down.

Bending up your own chassis is a necessary part of paying dues. You
can use found objects with a little metalwork as well.

The ST70 is no good? I have no idea.

What kind of circuits are better for beginners? SE or PP?

Thank you.

Martin

Single ended amps are simpler to build but you won't learn very much
for them and they sound, in general, pretty lame.

May I take you to task and ask how do SE sound compared to PP & why?

west

[thomas]

On Feb 4, 8:22 am, Jon Yaeger wrote:
in article om, thomas at
wrote on 2/3/07 7:42 PM:





On Feb 3, 4:09 pm, wrote:
Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Thanks.
-Martin

Here's one:

www.sparetimegizmos.com/Hardware/Stereo_6t9.htm

There is Wollensak 1280 tape recorder on Ebay right now for $43 buy-
it-now price. This will have all of the more expensive parts you need
for a stereo 6T9 amp. That is a little steep for this model, but it's
still cheaper than buying new transformers.

Drat. One of my "secrets" is out of the box.

One other Wollensak uses 7591s in class A with 6EU7 drivers.

I recycle the 7591s in higher wattage products, but the remaining iron makes
an awesome headphone amplifier (I have a .pdf of one I built if anyone
wants it). And the assembly has a shock-mounted 9 pin socket that is great
for minimizing microphonics in a preamp.

Jon- Hide quoted text -

- Show quoted text -


I think you just let your own secret out. I didn't say anything about
the 7591 models.

[John Byrns]

In article .com,
"Bret Ludwig" wrote:


Single ended amps are simpler to build but you won't learn very much
for them and they sound, in general, pretty lame.

May I take you to task and ask how do SE sound compared to PP & why?


Most single ended tube amplifiers have poor flatness at the low and
high frequency ends of the band, poor damping factor, and high
distortion. Note in theory single ended amps can be built that will
perform pretty well, but they are very heavy and expensive. The only
ones I have heard that were satisfactory used 211 or larger triodes.

Sonically, they will have weak and flabby bass and weak treble,
although the treble may not be as noticeable because little energy is
used up there in most cases. They will have a lot of distortion
products too, sometimes giving a false illusion of warmth and
fatness.

I understand why SE amps "have poor flatness at the low" end, and why
they have "high distortion", what I don't understand is why they would
have "poor flatness" at the high end, and "poor damping factor",
relative to equivalent PP amps? Can you explain the mechanism that
causes "poor damping factor" and "poor flatness" at high frequencies in
an SE amp? The damping factor issue is particularly mystifying to me as
I would expect PP amplifiers to generally have worse damping factors
than SE amplifiers since PP amps generally are more heavily loaded than
SE amps.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[robert casey]

To get to the levels easily approached by a pair of 6L6/807/KT66
tubes with single ended you have to go to transmitting tubes. They
look great but are not for the inexperienced. And why put up with 25
watts from a 211 SE when two will give a good 100-150?


The OP may only want a few watts output at first. I myself don't blast
my music. And it's said that "tube watts" go further, as tubes clip
more softly than SS amps do.

[Iain Churches]

"Bret Ludwig" wrote in message
oups.com...
On Feb 3, 4:09 pm, wrote:
Hello,

What is a more suitable project/circuit for a beginner DIYer? Where
are the sources to buy kits or parts (including tubes, chassis,
transformers)?

Is the ST70 project from Dynaco-Doctor a good choice?

Hmm. I wonder if a power amp is a good place to start?
I would have thought a simple preamp would be a good first step.
You also need to learn some basics as you go along. Bruce
Rozenblit's book "Beginner's Guide to Tube Audio Design"
covers quite a lot and also has some good projects you can
build.


Bending up your own chassis is a necessary part of paying dues. You
can use found objects with a little metalwork as well.

Homebrew chassis rarely look good, and most builders want to be
proud of the end result. Hammond have some good and reasonably
priced chassis, cover and cages. Later on you can progress to
copper and stainless steel:-)

Good luck
Iain

[Iain Churches]

"John Byrns" wrote in message
...
In article .com,
"Bret Ludwig" wrote:


Single ended amps are simpler to build but you won't learn very much
for them and they sound, in general, pretty lame.

May I take you to task and ask how do SE sound compared to PP & why?


Most single ended tube amplifiers have poor flatness at the low and
high frequency ends of the band, poor damping factor, and high
distortion. Note in theory single ended amps can be built that will
perform pretty well, but they are very heavy and expensive. The only
ones I have heard that were satisfactory used 211 or larger triodes.

Sonically, they will have weak and flabby bass and weak treble,
although the treble may not be as noticeable because little energy is
used up there in most cases. They will have a lot of distortion
products too, sometimes giving a false illusion of warmth and
fatness.

I understand why SE amps "have poor flatness at the low" end, and why
they have "high distortion", what I don't understand is why they would
have "poor flatness" at the high end, and "poor damping factor",
relative to equivalent PP amps? Can you explain the mechanism that
causes "poor damping factor" and "poor flatness" at high frequencies in
an SE amp? The damping factor issue is particularly mystifying to me as
I would expect PP amplifiers to generally have worse damping factors
than SE amplifiers since PP amps generally are more heavily loaded than
SE amps.

SETs traditionally have little or no global feedback, and so a higher
Z out. The two SETs that I have measured had a DF of about 2.5
and 3 respectively. A good PP amp can manage a factor of 15 to 20.
Presumably this is what Bret is referring to.

The higher levels of IMD on SET tend to make some music rather
muddled, particularly at higher levels. The Russian-built Resnekov
which I have listened to for many hours, reproduces the Shostakovich
Quartets with uncanny realism. For small-ensemble music at lowish
levels, SET can perform extremely well. There is, in my exprience,
certainly no evidence of "poor flatness" at high frequencies.

Regards to all
Iain

[John Byrns]

In article ,
"Iain Churches" wrote:

"John Byrns" wrote in message
...

I understand why SE amps "have poor flatness at the low" end, and why
they have "high distortion", what I don't understand is why they would
have "poor flatness" at the high end, and "poor damping factor",
relative to equivalent PP amps? Can you explain the mechanism that
causes "poor damping factor" and "poor flatness" at high frequencies in
an SE amp? The damping factor issue is particularly mystifying to me as
I would expect PP amplifiers to generally have worse damping factors
than SE amplifiers since PP amps generally are more heavily loaded than
SE amps.

SETs traditionally have little or no global feedback, and so a higher
Z out. The two SETs that I have measured had a DF of about 2.5
and 3 respectively. A good PP amp can manage a factor of 15 to 20.
Presumably this is what Bret is referring to.

So the issue with damping factor isn't SE vs. PP, it's negative feedback
vs. no negative feedback? It's a bit confusing to me to assume PP amps
have feedback and SE amps don't.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Arny Krueger]

"John Byrns" wrote in message


So the issue with damping factor isn't SE vs. PP, it's
negative feedback vs. no negative feedback?

Basically.

It's a bit
confusing to me to assume PP amps have feedback and SE
amps don't.

If you want to make an accurate amp, you will probably bypass SE and choose
PP. That's what the mainstream audio business did in the late 1920s and
early 1930s. After the invention of PP, the only justifications for SE were
low power, small size and low cost.

The whole idea of SE amps is to make the the most colored amp you can, and
avoid any technology that would lead to creation of an sonically accurate
amp. The two leading technologies for building clean amps have been PP and
NFB. Therefore most SE amps try to avoid them.

[Mark Aitchison]

wrote:
What is a more suitable project/circuit for a beginner DIYer? ...
Is the ST70 project from Dynaco-Doctor a good choice?

What kind of circuits are better for beginners? SE or PP?

Thank you.

Martin

What sort of price range were you thinking of? Are you after an amp
for a particular purpose or would just about any tube amp do
because you're keen on simply completing a tube project?? (In which case
something like the Silicon Chip magazine's preamp project is a good
starting point because the complexity of low, the box/PS is cheap, etc).

As far as power amps are concerned, I'd go for push-pull class A,
without being too ambitious - probably w-a-y under 15 W per channel so
you're in the territory of cheap valves and transformers, and avoid
tricky circuit techniques to squeeze the last ounce of power out. I
know there are people who swear by directly-heated single-ended triodes
in 1920's circuits with lots of coupling transformers, no feedback, and
unity-or-less damping factors, but this isn't an option for beginners...
you have to first be equipped with vintage high-efficiency speakers, and
(importantly) train your ears to like distortion ;-).

Having said that, I have to admit I recall liking an ECL86 amplifier
(one tube per channel, single-ended), and it was pretty darned simple.
Probably not a bad project if you don't need much power. I don't have
that particular circuit handy now, but you can get pretty much all the
clues you need from the Philips datasheets; I don't know of anybody
producing a proper kit for them though.

Oh, and Bret said...
I disrecommend toroids for outputs...

DISrecommend? Hmm, not sure. I agree for some situations non-toroids are
called for, but I'm interested to know what is wrong with 'em for simple
situations like this. It seems easy to find in toroids OP transformers
that are pretty low-fuss in terms of most of those failings output
transformers are famous for, such as frequency (and phase) response,
stray fields, weight/size/efficiency.

Mark A
ZL3TQE

[Charmed Snark[_2_]]

On 04 Feb 2007, robert casey wrote in
rec.audio.tubes:

To get to the levels easily approached by a pair of 6L6/807/KT66
tubes with single ended you have to go to transmitting tubes.
They look great but are not for the inexperienced. And why put up
with 25 watts from a 211 SE when two will give a good 100-150?


The OP may only want a few watts output at first. I myself don't
blast my music. And it's said that "tube watts" go further, as
tubes clip more softly than SS amps do.

This is commonly required for for home use guitar amps. You want it to
sound like it is maxed out, but you don't want to crack your windows
and receive divorce papers in the process. Sometimes, less really is
more.

Snark.

--
Posted via a free Usenet account from http://www.teranews.com