What are you matching these devices on both Chanel for? Idss ?
In that case how about matching those 3W power resistors and capacitors in circuits too. Because they are 5-10% tolerance rated for values.
So for all the commercial amplifiers they pick fets and transistors after these matching process of some kind, so there is no assymetry between channels.
I think it is far of a stretch!
In that case how about matching those 3W power resistors and capacitors in circuits too. Because they are 5-10% tolerance rated for values.
So for all the commercial amplifiers they pick fets and transistors after these matching process of some kind, so there is no assymetry between channels.
I think it is far of a stretch!
> What are you matching these devices on both Chanel for? Idss ?
We match them with curve tracer under working conditions (in the triode cell) at working temperature.
> In that case how about matching those 3W power resistors and capacitors in circuits too.
We match those to well below 0.5%
Patrick
We match them with curve tracer under working conditions (in the triode cell) at working temperature.
> In that case how about matching those 3W power resistors and capacitors in circuits too.
We match those to well below 0.5%
Patrick
Yes Mr. Pass thanks for generosity & gift of the jfet´s.
Warm thanks like class A heat sinks temperature are 😀
Attachments
A new LU kit would be wonderful! Perhaps something other than an voltage output section? Between them, vfets and Semisouths, it's been done. signed, Greedy.
> I've still got about 7,000. Maybe we should work up a kit in the store.
I hope someone would at least do some prematching beforehand, as Grey did years ago.
Here are some measurements for some we bought from Grey years ago (~4USD a piece).
As well as some others bought in China unmatched.
They were measured in circuit (a 200mA triode cell as used in the DAO headphone amp).
As you can see, even the prematched ones are not perfect.
For the triode cell to work properly, as even in the ZV9, one has to measure and adjust circuit accordingly.
See Nelson's original article.
In the DAO & DAO circlotron, we measured all prematched ones from Grey and from Deepsurplus from the same grouping.
With a large enough pool of >>100, we can match to < 0.5% over the working range.
Patrick
.
I hope someone would at least do some prematching beforehand, as Grey did years ago.
Here are some measurements for some we bought from Grey years ago (~4USD a piece).
As well as some others bought in China unmatched.
They were measured in circuit (a 200mA triode cell as used in the DAO headphone amp).
As you can see, even the prematched ones are not perfect.
For the triode cell to work properly, as even in the ZV9, one has to measure and adjust circuit accordingly.
See Nelson's original article.
In the DAO & DAO circlotron, we measured all prematched ones from Grey and from Deepsurplus from the same grouping.
With a large enough pool of >>100, we can match to < 0.5% over the working range.
Patrick
.
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EUVL still not sure the need for matching in ZV9 OR F3! As very few people are going to match resistors and capacitors as mentioned.
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> still not sure the need for matching in ZV9 OR F3!
That depends on what sort of DIY you want to do.
I have nothing to add as Nelson & ZM already did.
My last post was meant for Nelson, BTW.
Cheers,
Patrick
That depends on what sort of DIY you want to do.
I have nothing to add as Nelson & ZM already did.
My last post was meant for Nelson, BTW.
Cheers,
Patrick
In the original designs, the Jfets were tested for current with a specific
Source resistance and voltage, and then a chart suggesting additional
resistance in parallel gives the value which delivers the best 2nd harmonic
null after the cascode potentiometer is adjusted for output offset.
Under those circumstances you can think of the channels as matched.
Audiophiles being who they are will naturally want matched parts anyway.
Four dollars for matched parts? I'm Rich, Biotch!!
😀
The FETs might cost next to nothing if you get them in China.
But the matching, sorting and the order handling all cost time, and hence money.
Your time is certainly much more expensive then the 4 USD per FET.
😉
Patrick
But the matching, sorting and the order handling all cost time, and hence money.
Your time is certainly much more expensive then the 4 USD per FET.
😉
Patrick
5pcs LU1014D LU1014 N- Mosfet Transistor | eBay
Lovoltech LU1014D power JFET
in 2006, plus postage, plus bank charges.
LU1014D JFET's
Patrick
Lovoltech LU1014D power JFET
in 2006, plus postage, plus bank charges.
LU1014D JFET's
Patrick
Thanks Papa. That is what I understood too. EUVL is probably working for space agency of some kind it seems making amp channels that perfectly match with each other.😀
> EUVL is probably working for space agency of some kind
Not interesting enough for me. 😉
Patrick
Not interesting enough for me. 😉
Patrick
There's a good excuse for matching.
So let's see, at $1 original cost and 30 parts/hour at $3 profit.......
Naah, not worth it. Might as well give them away to DIYers.
😀
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