Re: Per review and other unqualified opinions
I have never had any problems with omitting these gates resistors except for power mosfet's.
Let's agree on that. Use them just in case or use them if you need them. Not against my religion to use them.
It's like : If it's ain't broken, don't fix it.Fred Dieckmann said:
I have never had any problems with omitting these gates resistors except for power mosfet's.
Let's agree on that. Use them just in case or use them if you need them. Not against my religion to use them.
Re: More Per review........
I think it's better though to take feedback from output. The emitter follower has emitter resistors as current limiters which increases the chances to stability.
Why don't optimize if it costs so little, just changing values? But if the feedback is taken where it is it's may be a good idea not to have too low values, low open-loop gain.Fred Dieckmann said:
I think it's better though to take feedback from output. The emitter follower has emitter resistors as current limiters which increases the chances to stability.
I see the point of not taking the feedback from the output, but
what about the commonly recommended alternative of simply
isolating the output with a series resistors (after the feedback
point)? Increases the Zout a bit, but not that much. Too late
to dig up references tonight, but I think Jung suggests just
that and also a number of opamp datasheets.
BTW, can somebody explain why there is a CCS and a current
mirror instead of just a CCS?
what about the commonly recommended alternative of simply
isolating the output with a series resistors (after the feedback
point)? Increases the Zout a bit, but not that much. Too late
to dig up references tonight, but I think Jung suggests just
that and also a number of opamp datasheets.
BTW, can somebody explain why there is a CCS and a current
mirror instead of just a CCS?
I dunno, SY.........
A well executed JFET pre-amp should have a polite, "easy to listen to", musical nature. While it may make you want to do The Shuffle, one would not expect it to have much Moeishness.
No, I would like to think that it would have a wry quality, that smiles quietly, and beckons: "Hey, schmuck.......come listen to this."
In which case, I would give it 1 1/2 "Harpo".
A well executed JFET pre-amp should have a polite, "easy to listen to", musical nature. While it may make you want to do The Shuffle, one would not expect it to have much Moeishness.
No, I would like to think that it would have a wry quality, that smiles quietly, and beckons: "Hey, schmuck.......come listen to this."
In which case, I would give it 1 1/2 "Harpo".
mikek said:
Strong word......i prefer sub-optimal...
I just wanted to contrast the "incompetent design" with FD's "a competent design", followed by a whole slew of posts from people telling how it could be improved, what was wrong, what should be changed etc. Sometimes it is really entertaining to read these treads.
Jan Didden
Re: Thanks for the suggestions Fred!
Freddie, since you're from Sweden too, where do you (intend to)
buy the 2SK170/2SJ74 devices? The only source I have found
in Sweden is JEC, and they are both expensive and reported to
have sold countefeit devices (although that were other types).
I have also found 3 or 4 others within EU who take web orders,
with varying prices for devices and freight/handling.
Freddie said:
Freddie, since you're from Sweden too, where do you (intend to)
buy the 2SK170/2SJ74 devices? The only source I have found
in Sweden is JEC, and they are both expensive and reported to
have sold countefeit devices (although that were other types).
I have also found 3 or 4 others within EU who take web orders,
with varying prices for devices and freight/handling.
Christer,
Well the only source for 2K170 and 2SJ74 in Sweden as far as I know is as you mentioned JEC.. But I'm planning on ordering them from Reichelt or perhaps from Borbelyaudio (matched). But Borbelyaudio is expensive, but perhaps its worth the cost to get them matched otherwise I will probably have to buy many and I will have to measure each one.
You mentioned counterfeit transistors from JEC. What kind of transistors were counterfeit? I recently bought some Sanken transistors and they looked to me as counterfeit, but I'm not 100% sure.
/Freddie
Well the only source for 2K170 and 2SJ74 in Sweden as far as I know is as you mentioned JEC.. But I'm planning on ordering them from Reichelt or perhaps from Borbelyaudio (matched). But Borbelyaudio is expensive, but perhaps its worth the cost to get them matched otherwise I will probably have to buy many and I will have to measure each one.
You mentioned counterfeit transistors from JEC. What kind of transistors were counterfeit? I recently bought some Sanken transistors and they looked to me as counterfeit, but I'm not 100% sure.
/Freddie
Freddie said:
Yes, I have the same problem, buy a lot from somewhere and
match them, or but matched ones from Borbely. BTW, It seems
Reichelt are a bit cumbersom when it comes to payment and
freight costs. I found two other sources that take web orders
and have reasonable prices.
http://www.grandata.co.uk
http://www.e44.com
I don't remember. I am almost certain it was mentioned in a
thread on thid forum once, but I couldn't find when trying
to search for it. BTW; don't make too much of it. I am afraid
it can happen occasionally to most suppliers, for instance if
some component is difficult to get so they have to buy them
through other channels than they usually do.
Christer, Freddie, why don't ask nicely the swedish distributor and explain to him why he should help you? I don't know right now which one you should ask, ACTE, Arrow, Eurodis??? ELFA knows, talk to "produktansvarig" for "halvledare".
This works sometimes.
Industrial prices are something else.
This works sometimes.
Industrial prices are something else.
Say...... you wouldn't be from Golgafrincham be any chance..
"Not really......good 'what-if' entertainment value.......but sub-optimal nevertheless......"
That absolutly comfirms it is a competent design!!! It is interesting that those who claim it is sub-optimal are woefully short of details on exactly what they would change and why....... There are always dozens of things one can do differently. The point was to illustrate why some of the design choices in the design were made. One can leave gate resistors out but having tuned the sound of tube circuits by the values of the grid resistors and having heard the degraded sonics from RF funnies, I don't. As a general reply to the armchair theorist and other hacks and as Jocko likes to provoke me (in an imitated voice of a former idiot boss I of mine that he calls Narajen Livingston Seagull), You are not qualified.......
When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him.
from Jonathan Swift's "Thoughts on Various Subjects, Moral and Diverting"
"Not really......good 'what-if' entertainment value.......but sub-optimal nevertheless......"
That absolutly comfirms it is a competent design!!! It is interesting that those who claim it is sub-optimal are woefully short of details on exactly what they would change and why....... There are always dozens of things one can do differently. The point was to illustrate why some of the design choices in the design were made. One can leave gate resistors out but having tuned the sound of tube circuits by the values of the grid resistors and having heard the degraded sonics from RF funnies, I don't. As a general reply to the armchair theorist and other hacks and as Jocko likes to provoke me (in an imitated voice of a former idiot boss I of mine that he calls Narajen Livingston Seagull), You are not qualified.......
When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him.
from Jonathan Swift's "Thoughts on Various Subjects, Moral and Diverting"
Attachments
peranders said:
Probably won't work with Elfa. A friend of mine recently asked
if they could get AD825s for him. The answer was that if he
needed a large quantity they would consider it. I might try
BHIAB, though. They say one should ask about transistors not
in their listing and when I think about it, neither of the 2SB649
and 2SD669 that I bought from them were in the price list.
However, I got a somewhat suspect brand of one of these types.
Otherwise I suppose it would probably be expensive anyway
if some of the companys you listed would agree to fix it, don't
you think?
BTW, Elfa does actually have the 2SJ170, but not its
complementary. In fact, last I checked they had only two or
three JFETs in total, all of them N-channel types.
Re: Whaddya mean ya can't find JFETs???
Never said we can't get them. It is merely a question of where
and at what prices. I try to avoid ordering from outside EU
since that always complicates matters, added VAT and customs
fees, usually higher postage fees etc.
You are welcome to quote me prices for the JFETs and freight,
though, and I'll consider it. Do you sell matched pairs too?
Jocko Homo said:
Never said we can't get them. It is merely a question of where
and at what prices. I try to avoid ordering from outside EU
since that always complicates matters, added VAT and customs
fees, usually higher postage fees etc.
You are welcome to quote me prices for the JFETs and freight,
though, and I'll consider it. Do you sell matched pairs too?
Re: Re: Whaddya mean ya can't find JFETs???
Hmmm....
Grab a pair of JFETs, add a few resistors and a trimpot (Steve Eddy had a circuit floating around here somewheres...) and sell the package as a unity gain buffer kits that have that "fabulous tube sound"
mlloyd1
(who is enjoying every single one of his 2SK147-V JFETS )
Hmmm....
Grab a pair of JFETs, add a few resistors and a trimpot (Steve Eddy had a circuit floating around here somewheres...) and sell the package as a unity gain buffer kits that have that "fabulous tube sound"
mlloyd1
(who is enjoying every single one of his 2SK147-V JFETS
)UrSv said:
Re: Re: Re: Whaddya mean ya can't find JFETs???
Or just tie the drain and source together and sell them as
exclusive diodes with JFET sound.
mlloyd1 said:Hmmm....
Grab a pair of JFETs, add a few resistors and a trimpot (Steve Eddy had a circuit floating around here somewheres...) and sell the package as a unity gain buffer kits that have that "fabulous tube sound"
mlloyd1
(who is enjoying every single one of his 2SK147-V JFETS
Or just tie the drain and source together and sell them as
exclusive diodes with JFET sound.
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