Reply
 
Thread Tools Display Modes
  #1   Report Post  
Posted to rec.audio.tubes
patrick-turner patrick-turner is offline
external usenet poster
 
Posts: 119
Default JADIS amp reformation

Hi all r.a.t regulars, and to anyone searching about Jadis SE300B amps.
I have put up a page detailing my work on reforming a pair of Jadis last month at http://www.turneraudio.com.au/Jadis-300B-reformed.html

Anyone wanting to make a decent sounding/measuring 16 Watt SET amp are invited to have a look.

Patrick Turner
  #2   Report Post  
Posted to rec.audio.tubes
GRe GRe is offline
external usenet poster
 
Posts: 67
Default JADIS amp reformation


"patrick-turner" wrote in message
...

Anyone ... invited to have a look.


Even(!) Audiophools agree to your findings:
"The Jadis also measures worse ...; it has a severely compromised bass
response"
http://www.stereophile.com/content/j...ivsi-listening

Don't read the rest, it's a waste of time.

Impossible not to stumble over your SE transformer test jig.
My 2(euro)cent about how I test transformer inductance.

Use courier font!


T1
Variac L1
L O-----)|( +----------------------):
)|( | ):
)|( T2 C1 | DUT ):
)|(----)|(-----||-----o-----)|(--- +-):
)|( )|( - + | )|( |
)|( )|( | )|( (I)
)|( )|( (V) )|( | +
)|( )|( | )|( +---+
)|( )|( | )|( | | DC-supply
N O--o--)|(--o--)|(---o--[R1]--o-----)|(--- +---+
| | | | | -
+-------+ +--(V)---+--------------------+

Basically the same to your set-up, but with some more flexibility.
R1 & C1 are identical to what you chose in your jig.
For L1 I use a 8H/460mA/60ohm-DRC choke thats handy, inductance
high enough to reject the ac and dcR/Idc good enough to enable
adequate Idc at a reasonable DC-supply voltage.

T2 is 220/2x 24V, with T1 at full trottle it's output is 58Vac.
For higher Vac I use an isolating variac, without T2 of course.
F.e., characterization of chokes destined for LC-filters high
Vac (may) show quite different inductance than at low Vac.
An Amroh 1505 choke tested this way showed 7.5H @ 200Vac/150mAdc
against 5.8H @ 20Vac/150mAdc, 30% more.


To measure leakage induction I'm working on a SS Amp.
Probably such a set-up makes the above one superfluous.

L1
SS Amp. +----------------------):
+-------+ | ):
| |\ | T3? C1 | DUT ):
+-----| | |----)|(-----||-----o-----)|(---+ +-):
| | |/ | )|( - + | )|( | |
| +---+---+ )|( | )|( | (I)
| | )|( (V) )|( | | +
(FG*)1kHz | )|( | )|( | +---+
| | )|( | )|( | | | DC-supply
+---------+--------)|(---o--[R1]--o-----)|(---+ +---+
| | | -
+--(V)---+--------------------+

*Hint for Phil, see the distortion spec. of HP3325A(+HV option).

BTW, you deliberately ignored "Rw" to calculate "Lp" for practical reason?

Regards,
Gio


Patrick Turner







  #3   Report Post  
Posted to rec.audio.tubes
patrick-turner patrick-turner is offline
external usenet poster
 
Posts: 119
Default JADIS amp reformation

On Monday, 3 December 2012 02:04:53 UTC+11, GRe wrote:
"patrick-turner" wrote in message ... Anyone ... invited to have a look. Even(!) Audiophools agree to your findings: "The Jadis also measures worse ...; it has a severely compromised bass response" http://www.stereophile.com/content/j...ivsi-listening Don't read the rest, it's a waste of time. Impossible not to stumble over your SE transformer test jig. My 2(euro)cent about how I test transformer inductance. Use courier font! T1 Variac L1 L O-----)|( +----------------------): )|( | ): )|( T2 C1 | DUT ): )|(----)|(-----||-----o-----)|(--- +-): )|( )|( - + | )|( | )|( )|( | )|( (I) )|( )|( (V) )|( | + )|( )|( | )|( +---+ )|( )|( | )|( | | DC-supply N O--o--)|(--o--)|(---o--[R1]--o-----)|(--- +---+ | | | | | - +-------+ +--(V)---+--------------------+ Basically the same to your set-up, but with some more flexibility. R1 & C1 are identical to what you chose in your jig. For L1 I use a 8H/460mA/60ohm-DRC choke thats handy, inductance high enough to reject the ac and dcR/Idc good enough to enable adequate Idc at a reasonable DC-supply voltage. T2 is 220/2x 24V, with T1 at full trottle it's output is 58Vac. For higher Vac I use an isolating variac, without T2 of course. F.e., characterization of chokes destined for LC-filters high Vac (may) show quite different inductance than at low Vac. An Amroh 1505 choke tested this way showed 7.5H @ 200Vac/150mAdc against 5.8H @ 20Vac/150mAdc, 30% more. To measure leakage induction I'm working on a SS Amp. Probably such a set-up makes the above one superfluous. L1 SS Amp. +----------------------): +-------+ | ): | |\ | T3? C1 | DUT ): +-----| | |----)|(-----||-----o-----)|(---+ +-): | | |/ | )|( - + | )|( | | | +---+---+ )|( | )|( | (I) | | )|( (V) )|( | | + (FG*)1kHz | )|( | )|( | +---+ | | )|( | )|( | | | DC-supply +---------+--------)|(---o--[R1]--o-----)|(---+ +---+ | | | - +--(V)---+--------------------+ *Hint for Phil, see the distortion spec. of HP3325A(+HV option). BTW, you deliberately ignored "Rw" to calculate "Lp" for practical reason? Regards, Gio Patrick Turner


I find it hard to follow anyone using text to draw a schematic.
I've tested numerous transformers in various ways, and I happen to have a LV PSU which I recently rewired for something else, and was able to use it to test the Jadis OPT out of its circuit. Before condemning the OPTs, I needed a "second" opinion, and the that was provided my my test circuit shown which most competent ppl should understand. I already had tested it in the amp at low level and with 10r in series with OPT from tubes, with no loading..
There was no need to include Rw in calculations because it is a very low R figure and the measured Lp with DC flow was 1H at 50Hz, ie, XLp = approx 314 ohms.
I wasn't aware Sterophile gave the Jadis a poor review. But it is sure fixed now, and has become the music angel with golden voice.
Patrick Turner

  #4   Report Post  
Posted to rec.audio.tubes
GRe GRe is offline
external usenet poster
 
Posts: 67
Default JADIS amp reformation


"patrick-turner" wrote in message
...

I find it hard to follow anyone using text to draw a schematic.


One way to read the message:

- go to:
http://groups.google.com/group/rec.a...387e05c?hl=nl#

- select the schematic(s) or the entire message.

- copy & paste into WORD f.e.

- select once again (in WORD this time).

- set the selection to "Courier" font.

That should do it.

Regards,
Gio


Patrick Turner




  #5   Report Post  
Posted to rec.audio.tubes
Alex Pogossov Alex Pogossov is offline
external usenet poster
 
Posts: 95
Default JADIS amp reformation


"patrick-turner" wrote in message
...
Hi all r.a.t regulars, and to anyone searching about Jadis SE300B amps.
I have put up a page detailing my work on reforming a pair of Jadis last
month at http://www.turneraudio.com.au/Jadis-300B-reformed.html

Anyone wanting to make a decent sounding/measuring 16 Watt SET amp are
invited to have a look.

Patrick Turner


I found using timber circuit boards funny. dielectric absorbtion and
nonlinear leakage conduction due to the residual moisture in timber will
cause sound coloration. Definitely such insulator will give a "wooden"
sound -- shallow, flaccid, limp bass.

Real audiophools with determinations always use teflon -- no absorbtion, no
leakage, easily machined, cut, drilled. You can dril blind holes and drive
screws and pins into them. Will not carbonise, burn or change properties
when overheated during soldering or when a component is burning.

Also I noticed that balancing of the filaments of 300Bs with 33R series
resistors is unnecessary. With the DC filament supply, one end of the
filament is ALWAYS 5V higher or lower, no matter where the self-bias circuit
is connected. Thus the last 5V of the grid voltage swing is underused,
because grid current from the more negative end of the cathode will prevent
full emission on the more positive end. Similraly, this 5V skew smears the
tube cut-off -- one end might be cut-off while the other is conducting.

Besides the cathode is wearing unevenly, one end always bearing more
emission current, but this should not be a tube life limiting factor.

So this balancing is just a sterotypical thinking. The four 33R resistors
can be safely removed. Now, depending on whether the self-bias circuit is
connected to a positive or a negative end of the filament, one would have
less or more fixed bias mixed respectively.




  #6   Report Post  
Posted to rec.audio.tubes
patrick-turner patrick-turner is offline
external usenet poster
 
Posts: 119
Default JADIS amp reformation

On Tuesday, 4 December 2012 22:42:12 UTC+11, Alex Pogossov wrote:
"patrick-turner" wrote in message ... Hi all r.a.t regulars, and to anyone searching about Jadis SE300B amps. I have put up a page detailing my work on reforming a pair of Jadis last month at http://www.turneraudio.com.au/Jadis-300B-reformed.html Anyone wanting to make a decent sounding/measuring 16 Watt SET amp are invited to have a look. Patrick Turner I found using timber circuit boards funny. dielectric absorbtion and nonlinear leakage conduction due to the residual moisture in timber will cause sound coloration. Definitely such insulator will give a "wooden" sound -- shallow, flaccid, limp bass.


Wooden boards for circuits have been used for last 150 years. They were routinely used in early radio circuits where circuit impedances were often high in hundreds of k-ohms.

I have measured all use of timber and found the only place one has to worry about the multi megohn resistance between 2 screws 10mm apart is for grid circuits where Z is high and there is a HV connection on the same peice of wood. The wood tends to charge up, and you get a tiny Vdc someplace where you were not to expect it.
But your statement "Definitely such insulator will give a "wooden" sound -- shallow, flaccid, limp bass." - is utter rubbish because the bass quality of the reformed Jadis is nothing short of spectacular, and sounds like a good 50W amp.

Real audiophools with determinations always use teflon -- no absorbtion, no leakage, easily machined, cut, drilled.

Audiophules with determination like to believe they know best by using teflon that almost nobody else uses because of cost and difficulty in its use and the inability to use glue to fix it. Audiopules are notoriously pig-ignorant, knowing almost zero about real world electronic or metal engineering or about electronic properties of material and how they affect distortions and noise and sound. What they DO KNOW is mostly a jumble of bull**** notions not based on any known facts, but based on "what others have said" on the Net, and on slaes BS and on what Stereophile authors have poked down their necks. They then profess to be able to tell if any special capacitor brand has been used or special wore of special any fukken thing. Fact is, when I have yested their perceptive abilities, they rarely can pick whether I have used Wima caps or Auricaps, teflon or polyester, or any difference between either solid state amps I have made, or tube amps. Turns out the audio enthusiasts who are not complete raving loonies like whatever I make.

You can dril blind holes and drive screws and pins into them. Will not carbonise, burn or change properties when overheated during soldering or when a component is burning.

I understand all that, and would love to used 10mm x 10mm bars of teflon to make up circuit terminal strips. Its fiendishly expensive stuff. Probably, like so many modern plastics, its production causes an environmental nightmare somewhere.
The amps I build rarely ever need to be worked on later because anything to be done by anyone other than myself would make things worse, because nobody understands his own product better than me.
So, having wired up the Jadis with a few hardwood plywood boards and hardwood terminal strips using brass plated steel cupboard hinge screws for terminals, its more than likely they'll never ever be changed. If someone were to acquire what I have done and replace terrible horrid wood with teflon, they'd be telling a whopping lie if they insisted it sounded better. One could say music should sound organically wondrous, and be supported on natural substances where possible, including wood, and iron, copper, silicon because all are natural, ie, found on our planet, without much monstering and adulteration by industry. Wood Knot Teflon sound clinical, dry, souless, empty,and unacceptable? Bloody audiopule arguments can be reversed back onto the stupid *******s. Fact is Jadis SE300W amps were a bloody horror story, and now at least just TWO samples sound wonderful. The Jadis site says they are discontinued, and I guess, and I am only guessing, maybe all samples of that model had OPTs without any air gap, plus the whole pile of other circuit mistakes and design mistakes which made +1,000 dB more worsening of sound than any timber board for CCS transistor and protection board, and test terminals for monitoring Iadc and Iac of each 300B without needing to move it..

Also I noticed that balancing of the filaments of 300Bs with 33R series resistors is unnecessary. With the DC filament supply, one end of the filament is ALWAYS 5V higher or lower, no matter where the self-bias circuit is connected.

There is few mV of hum across the cathodes. Its negligible. But when I made amps with 845, guess what, even with cathode Vdc and few mV of hum, a fraction of a mV got into output so balancing is GOOD PRACTICE even though you say its BS.

Thus the last 5V of the grid voltage swing is underused, because grid current from the more negative end of the cathode will prevent full emission on the more positive end.

In theory, you are correct, in practice, its BS. The difference in emission along the cathode is utterly negligible and unimportant to operation. Would you care to quantify your argument? Jadis had used a regulated 5Vdc for 300B and hum was less than a mV, but they had two balancing 47r resistors. Trouble weas they used just one 5Vdc supply common to both 300B - big mistake when tubes are not matched, and running too hot anyway. The very slight amount of unbypassed resistance in my TWO reformed Rk+Ck circuits = 38 ohms, and the very slight amount of local current FB does SFA good, bad, or otherwise except stop the two parallel cathode bypass caps ever being over currented with AC from low Z of 300B cathode. Not likely in fact.

Similraly, this 5V skew smears the tube cut-off -- one end might be cut-off while the other is conducting.

This is a hi-fi use of class A 300B and they never go anywhere near cut off..
Your argument does not hold water.

Besides the cathode is wearing unevenly, one end always bearing more emission current, but this should not be a tube life limiting factor.

And it just does not matter!

So this balancing is just a sterotypical thinking.

The balancing was a necessity where AC was routinely used in many amps for heating. Usually a hum nulling pot was used, and even in PP amps the nulling is never perfect and in a pair of Sun amps with 2A3 I repaired 10 years ago the AC heating and pot were retained, and I gave a pair of headphones the owner could use for nulling. That worked, and noise only seldom appeared at speakers. My 55W SE55 with 845 had less than 0.25mV of total noise at output. I know all about how to build amps with low noise, and I'll do it my way, and not yours.

The four 33R resistors can be safely removed.

Indeed, but they are staying put.

Now, depending on whether the self-bias circuit is connected to a positive or a negative end of the filament, one would have less or more fixed bias mixed respectively.

The Reformed Jadis now have individual R&C cathode biasing. Audio Note makes a similar amp with similar fatures to what I have done. It works, and cannot easily be ****ed right up by some idiot audio nutter who always manages to get his testicles in a knot when he tries to adjust the "fixed bias" which of course is unfixed, and adjustable, and thus able to cause mahem among the Dopes. My dear customer here has an excellnt range of human abilities, and a fine man he is, but he just has no clue how to use a voltmeter, like 99% of the rest of the population. Leak and Quad used cathode biasing for obvious reasons although I'd say again Quad were idiots to have one lone 180r to bias both KT66.
But maybe Peter Walker owned shares in the MOV tube making Co, so the more KT66 people bought because of bias failure with his crummy biasing meant he got richer. Plus, omitting one R and one C allowed him to buy a Morris Major in 1960instead of a Morris Minor, wow, wonders wood never cease.

BTW, about 10 years ago I totally re-engineered a large stereo VAC amp with 4 x 300B per channel. Jadis ain't alone and producing rubbish that smokes. Anyway, in went timber circuit strips, worked well, very rugged, but the grid cicuits did use teflon insulated wires point to point with no grid potential points to any wood board/strip. Caps were boxed polypropylene Wimas siliconed to chassis so that the grid wiring could be slung from short cap leads acting as terminals.
Certainly no lossy PCB boards were used, with stuff all jammed tight, and boards blocking natural air convection flows. Don't worry Alex, I know what I am doing.

I have done many amps over the last 18 years and not one has had to be returned as a result of my poor tradesmanship. I'm now retired, and may not make too many more amps.

Patrick Turner.
  #7   Report Post  
Posted to rec.audio.tubes
Alex Pogossov Alex Pogossov is offline
external usenet poster
 
Posts: 95
Default JADIS amp reformation


"patrick-turner" wrote in message
news:0bad46cc-e336-417e-ac98-.....

But your statement "Definitely such insulator will give a "wooden" sound --
shallow, flaccid, limp bass." - is utter rubbish because the bass quality of
the reformed Jadis is nothing short of spectacular, and sounds like a good
50W amp.



***
I was only kidding and teasing. Sorry if you took offence.

Probably wood is OK if you do not drive +500V screws near some sensitive
grid circuits screws... But I would not use timber. Teflon is very costly,
of course, so I use polysterene sheets or even pieces of kitchen plastic
cutting boards, but they are not high temperature material. Only low power
circuits can be laid out on them.
***



Real audiophools with determinations always use teflon -- no absorbtion, no
leakage, easily machined, cut, drilled.

Audiophules with determination like to believe they know best by using
teflon that almost nobody else uses because of cost and difficulty in its
use and the inability to use glue to fix it. Audiopules are notoriously
pig-ignorant, knowing almost zero about real world electronic or metal
engineering or about electronic properties of material and how they affect
distortions and noise and sound. What they DO KNOW is mostly a jumble of
bull**** notions not based on any known facts, but based on "what others
have said" on the Net, and on slaes BS and on what Stereophile authors have
poked down their necks. They then profess to be able to tell if any special
capacitor brand has been used or special wore of special any fukken thing.
Fact is, when I have yested their perceptive abilities, they rarely can pick
whether I have used Wima caps or Auricaps, teflon or polyester, or any
difference between either solid state amps I have made, or tube amps. Turns
out the audio enthusiasts who are not complete raving loonies like whatever
I make.

You can dril blind holes and drive screws and pins into them. Will not
carbonise, burn or change properties when overheated during soldering or
when a component is burning.

I understand all that, and would love to used 10mm x 10mm bars of teflon to
make up circuit terminal strips. Its fiendishly expensive stuff. Probably,
like so many modern plastics, its production causes an environmental
nightmare somewhere.
The amps I build rarely ever need to be worked on later because anything to
be done by anyone other than myself would make things worse, because nobody
understands his own product better than me.
So, having wired up the Jadis with a few hardwood plywood boards and
hardwood terminal strips using brass plated steel cupboard hinge screws for
terminals, its more than likely they'll never ever be changed. If someone
were to acquire what I have done and replace terrible horrid wood with
teflon, they'd be telling a whopping lie if they insisted it sounded better.
One could say music should sound organically wondrous, and be supported on
natural substances where possible, including wood, and iron, copper, silicon
because all are natural, ie, found on our planet, without much monstering
and adulteration by industry. Wood Knot Teflon sound clinical, dry, souless,
empty,and unacceptable? Bloody audiopule arguments can be reversed back onto
the stupid *******s. Fact is Jadis SE300W amps were a bloody horror story,
and now at least just TWO samples sound wonderful. The Jadis site says they
are discontinued, and I guess, and I am only guessing, maybe all samples of
that model had OPTs without any air gap, plus the whole pile of other
circuit mistakes and design mistakes which made +1,000 dB more worsening of
sound than any timber board for CCS transistor and protection board, and
test terminals for monitoring Iadc and Iac of each 300B without needing to
move it.

Also I noticed that balancing of the filaments of 300Bs with 33R series
resistors is unnecessary. With the DC filament supply, one end of the
filament is ALWAYS 5V higher or lower, no matter where the self-bias circuit
is connected.

There is few mV of hum across the cathodes. Its negligible. But when I made
amps with 845, guess what, even with cathode Vdc and few mV of hum, a
fraction of a mV got into output so balancing is GOOD PRACTICE even though
you say its BS.

Thus the last 5V of the grid voltage swing is underused, because grid
current from the more negative end of the cathode will prevent full emission
on the more positive end.

In theory, you are correct, in practice, its BS. The difference in emission
along the cathode is utterly negligible and unimportant to operation. Would
you care to quantify your argument? Jadis had used a regulated 5Vdc for 300B
and hum was less than a mV, but they had two balancing 47r resistors.
Trouble weas they used just one 5Vdc supply common to both 300B - big
mistake when tubes are not matched, and running too hot anyway. The very
slight amount of unbypassed resistance in my TWO reformed Rk+Ck circuits =
38 ohms, and the very slight amount of local current FB does SFA good, bad,
or otherwise except stop the two parallel cathode bypass caps ever being
over currented with AC from low Z of 300B cathode. Not likely in fact.

Similraly, this 5V skew smears the tube cut-off -- one end might be cut-off
while the other is conducting.

This is a hi-fi use of class A 300B and they never go anywhere near cut off.
Your argument does not hold water.

Besides the cathode is wearing unevenly, one end always bearing more
emission current, but this should not be a tube life limiting factor.

And it just does not matter!

So this balancing is just a sterotypical thinking.

The balancing was a necessity where AC was routinely used in many amps for
heating. Usually a hum nulling pot was used, and even in PP amps the nulling
is never perfect and in a pair of Sun amps with 2A3 I repaired 10 years ago
the AC heating and pot were retained, and I gave a pair of headphones the
owner could use for nulling. That worked, and noise only seldom appeared at
speakers. My 55W SE55 with 845 had less than 0.25mV of total noise at
output. I know all about how to build amps with low noise, and I'll do it my
way, and not yours.

The four 33R resistors can be safely removed.

Indeed, but they are staying put.

Now, depending on whether the self-bias circuit is connected to a positive
or a negative end of the filament, one would have less or more fixed bias
mixed respectively.

The Reformed Jadis now have individual R&C cathode biasing. Audio Note makes
a similar amp with similar fatures to what I have done. It works, and cannot
easily be ****ed right up by some idiot audio nutter who always manages to
get his testicles in a knot when he tries to adjust the "fixed bias" which
of course is unfixed, and adjustable, and thus able to cause mahem among the
Dopes. My dear customer here has an excellnt range of human abilities, and a
fine man he is, but he just has no clue how to use a voltmeter, like 99% of
the rest of the population. Leak and Quad used cathode biasing for obvious
reasons although I'd say again Quad were idiots to have one lone 180r to
bias both KT66.
But maybe Peter Walker owned shares in the MOV tube making Co, so the more
KT66 people bought because of bias failure with his crummy biasing meant he
got richer. Plus, omitting one R and one C allowed him to buy a Morris Major
in 1960instead of a Morris Minor, wow, wonders wood never cease.

BTW, about 10 years ago I totally re-engineered a large stereo VAC amp with
4 x 300B per channel. Jadis ain't alone and producing rubbish that smokes.
Anyway, in went timber circuit strips, worked well, very rugged, but the
grid cicuits did use teflon insulated wires point to point with no grid
potential points to any wood board/strip. Caps were boxed polypropylene
Wimas siliconed to chassis so that the grid wiring could be slung from short
cap leads acting as terminals.
Certainly no lossy PCB boards were used, with stuff all jammed tight, and
boards blocking natural air convection flows. Don't worry Alex, I know what
I am doing.

I have done many amps over the last 18 years and not one has had to be
returned as a result of my poor tradesmanship. I'm now retired, and may not
make too many more amps.

Patrick Turner.


  #8   Report Post  
Posted to rec.audio.tubes
patrick-turner patrick-turner is offline
external usenet poster
 
Posts: 119
Default JADIS amp reformation

On Thursday, 6 December 2012 00:04:34 UTC+11, Alex Pogossov wrote:
"patrick-turner" wrote in message news:0bad46cc-e336-417e-ac98-..... But your statement "Definitely such insulator will give a "wooden" sound -- shallow, flaccid, limp bass." - is utter rubbish because the bass quality of the reformed Jadis is nothing short of spectacular, and sounds like a good 50W amp. *** I was only kidding and teasing. Sorry if you took offence. Probably wood is OK if you do not drive +500V screws near some sensitive grid circuits screws...


Its usually very easy to choose terminal locations to avoid high PD between connection points that are close. I do it routinely, with whatever board material I use.

I don't take offense, anyone is free to criticise, and then they should expect my robust defence of my practices. But hardwood ply well sealed with polyurethane varnish IS good enough for amps made in very low numbers by DIYers, or by specialist pp like myself. Its all about HOW one used stuff. In the under-chassis space in the original Jadis they had a small heatsink to dissipate 13Watts from cathode heater regulator, plus a single Rk at about 10W plus other R so total heat under chassis was about 25Watts. This doesn't escape easily, so chassis got quite warm and temp under chassis tended to be hot. Moving all hot R to a larger heatsink above chassis meant underchassis is cool as cucumber and nothingis heat-stressed. Nothing hot is used near anything wood. Come back in 50 year's time and all will still be well. Timber was routinely used in oil filled HV transformers.

But I would not use timber. Teflon is very costly, of course, so I use polysterene sheets or even pieces of kitchen plastic cutting boards, but they are not high temperature material. Only low power circuits can be laid out on them.

Kitchen cut-board is crap because of low temp melt. Never leave one near hot-plates. But small fragments of board end up in food and I guess they are inert. I have used the same wood cut board I made for 30 years now.
Plastic Cut boards Great insulaion, they seem to be polyethylene or polythene. You can't heat it, and screws will loosen, and so I'd never use it. But, polythene is good else where and has extensive apps because its dielectric constant is so low at about 1.5.

Kitchen top laminate used to cover particle board cabinets is available usually in 0.8mmm thicknesses and it you glue several layers together it makes a good phenolic board. Offcuts can often be found in joinery dumster bins. It tends to curl over time, and needs to be stored flat. Some is thicker than 0.8. Using 2 glued with good contact glue well applied seems OK. 1.2mm copper wire tracks can be used with wire hooked under board so lamintions won't come undone. One used to be able to buy 3mm thick un-drilled sheets meant for circuits, maybe you still can, but I ain't seen any around, except what's taken from old gear. Its excellent stuff for small boards and for home made turret strips where strips 15mm wide are cut and mounted on stand-offs. Some shops sell pre-drilled phenolic board to suit DIY circuit boards for SS projects and holes are and 0.1 inch centres to suit opamps etc. Its like the old "biscuit boards" used in countless TVs sets and cheap electronics. Its less than 2mm thick, and brittle, but glued up layers are OK. Now many ppl expect to see fibreglassed resin boards used. Best are 3mm thick, but usually only 2mm is used. Jadis had white fibre glass 2mm usually used for making transformer bobbins. I've used ths too, and its OK. The boards can absorb moisture into fibres, but while kept dry they are OK, so after making a board and parting it, I paint over with varnish including all edges. Making tag trips with strips of fibreglass is doable, but its flimsy like the cheap tagstrips using pressed metal lugs on the thin phenolic biscuit board, usually 8 lugs for $2. As long as thay re not disturbed, tagstrips last indefinately, as I have seen in so much old gear. Latest tag strips I bought had Bean Counter metal lugs, and metal lug thickness has suddenly been halved, and what was equivalent to old stuff is now quite inferior, so I won't be buying any more for old radio work. Ther's always some **** who thinks he's a fukken hero by making a product crummy. I'm no fan of turrets. I have seen many examples where they have become loose, or are on verge of pulling out - even in Quad-II-40, which has terrible board and parts layout underchassis.

Where you want a terminal to remain forever in a fibreglass or phenololic board or in 5mm hardwood ply, the use of M2mm brass bolts and nuts is hard to beat.
No rivetting. Nut on bolt is far more reliable. I've used such to terminate many winding connections from an OPT on a board fixed to the bobbin. Its neat and tidy, and terminals don't losses much with repeat soldering, say for changing load matching of the OPT. In the Jadis, the original had 8 x M4 bolts in a 2mm fibreglassed board for the OPT terminations. But in the revised amp, there is onlt ONE wire which needs to be moved to one of 3 available screws in a wood strip. It'd take years for re-soldering to ruin the wood. The wood withstands the heat OK, and sure, the screw that was tight becomes loose, and easily turned, but no more than that and the course thread retains very strong attachment in the wood. I've got the Jadis set up for max SE PO to occur for 5.3 ohms which suits everyone with speakers with Z above 3 ohms, so the termiations won't need to be changed - ever. But some audiophule may well try to change it sometime in the future. They'll whinge and moan and bitch on to their mates, while not knowing what they do, and are likely to get muddled, use 12 ohm terminal, then connect 4 ohm speakers, because well, 4 ohms is less ohms, so it must be easier to drive, and you get more "drive" from "higher" ohm outlet. I cannot guard against idiots.

Of course if anyone insists on me using teflon, and on anything else "special", then fine, they pay the extra, no problem. Some insisted I use high silver content solder, OK, they have to buy a roll for me. Now we have lead free solder, and I'm not sure if audiophules hate that too. But its everywhere now, and you need a hotter soldering iron it seems.

Patrick Turner.
Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Jadis & KT88s CyberSlacker Vacuum Tubes 2 September 17th 08 11:39 PM
Jadis help Cyberslacker Vacuum Tubes 0 November 3rd 07 07:38 PM
WTB: Jadis Defy 7 Amplifier Yann Vacuum Tubes 0 December 1st 04 11:31 AM
Jadis amps Philip Lawrence Vacuum Tubes 0 January 18th 04 02:01 AM
FS : Jadis intergated CyberSlacker Marketplace 0 July 1st 03 04:57 AM


All times are GMT +1. The time now is 12:34 AM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"