Has anyone seen this front-end before?

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#781
AndrewT said:
How do we, the customers, know whether we have ruby, or green or more inferior mica in our capacitors?
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Andrew, the best way I can think of is looking at the manufacturers reputation and prices but even reputable ones do sell the lesser quality micas for use where DA is not so important. The manufacturers using ruby usually state this in the specifications as to explain the higher prices.
 
#783
AndrewT said:
I could just ask RS online, or Farnell, or any of a number of suppliers which mica is in their product.

I think I already know what they might say, if they bother to give me any response.
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😀😀😀

Most of the staff working at these companies have no idea what a transistor is, they work according to numbers given to objects and some have never seen them before in their lives. I guess you could find higher someone higher up the ladder that may know more but this kind of detail I doubt.

See the folowing link
Silver Mica Capacitors homepage
 
#784
I like SM for Cdom because my clues are normally in the 20 to 30pF of range and film is hard to get at those values.

The prices shown in the link are quite high btw. Typically they sell for around $1.

I've heard a lot of bad things about these devices, but my experiences are nothing but positive.
 
#785
homemodder said:
😀😀😀

Most of the staff working at these companies have no idea what a transistor is, they work according to numbers given to objects and some have never seen them before in their lives. I guess you could find higher someone higher up the ladder that may know more but this kind of detail I doubt.

See the folowing link
Silver Mica Capacitors homepage
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And at two squid a pop, do they sound ten times better than these?
 
#786
Bonsai said:
I like SM for Cdom because my clues are normally in the 20 to 30pF of range and film is hard to get at those values.

The prices shown in the link are quite high btw. Typically they sell for around $1.

I've heard a lot of bad things about these devices, but my experiences are nothing but positive.
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Thats what we were discussing, not all mica caps are of same quality, I wouldnt touch the 1 $ types, the good quality low DA SM dont sell for those kind of prices. I only use polystyrene, my favourites were the old 1 % philips but sadly discontinued. I get polystyrene for cheaper than SM and I know I dont have any DA to worry about.

PS careful handling ( while soldering) and placement is required with polystyrene.
 
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#788
Waly said:
And at two squid a pop, do they sound ten times better than these?
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No, Id use that type if low price was paramount, I only pointed out that one does get better quality SM without such high DA, not that they are better than other types because they sound better. Id only probably go with 2 percent NPO that I see on the market and still pretty cheap. I dont see any benefits in using SM over polistyrene teflon or NPOs and because the good quality ones are so expensive I dont use SM at all.
 
#789
Bonsai said:
The $1 types are Cornell Dubilier from DK and Mouser. They are good.
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Maybe, I wonder what their DA is ?? Id only use what cornell call the high frequency dipped types but I think those dont cost a dollar ?? Those are probably Ruby types with lower DA characteristics.

PS, just checked 1,5$ and still I dont see any benefits over polistyrene or NPOs, in fact even the best quality SM will always be inferior when it comes to DA.
 
#791
There's no evidence that DA is a problem. There's been a long and learned debate over on the Blowtorch thread about caps. Other than just plain bad quality ones, or devices not suited to the job, I am afraid we are still in the dark on this subject for the most part.
 
#792
Strictly speaking theory, it should be, at audio frequencies perhaps not so important but it definitly is not desireable so why would one want to use something that has known flaw and better yet pay higher price for it.

Here we only have it sounds better argument by some, how can a flawed component sound better than a non one ?? Agreed we still in the dark here.

BTW what happened to Edmond, Eager to hear of the progress with this amp.
 
#795
LTP + cascode with no current mirror.

Neither Self or Cordell really cover the LTP with a cascode but no current mirror.
Just noticed that Slone uses it but doesn't seem to be well covered in the table of contents or index of his book.
But it is more or less what the AD797 is based on and Edmond's circuit here so perhaps it is worth some analysis😉
Does anyone know of a decent reference for this?

Best wishes
David
 
#799
Thanks Arthur for the link. I will look at it immediately.
As to "analyse" - Thanks to Andrew (Bonsai) I found the R D Middlebrook site
and like the way he tries to analyse into elements that are comprehensible and therefore simplify design. Best to read Middlebrook rather than my summary because the work is excellent, extensive and freely available. It represents the lifetime work of a smart PhD so there is a lot to understand but it is a fine memorial.
So basically I want do Middlebrook-style Design Oriented Analysis.

Best wishes
David

PS. Nice site!
 
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#800
Layout?

Been a bit quiet lately - everyone must be busy with details of the PCB layout for the superTIS😉
I have a few ideas at the back-of-envelope level but no layout software yet.
Has anyone else actually considered the layout or have any comments?

David
 
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