[nikongod]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif As DIYers we look down on some brands of capacitors, and i'm stating to think that it's because the labels look dull.

it would be exceptionally nice if any of these guys posted a linearity graph that applied to the audio band.

there are almost certainly some "diamonds in the rough" out there, but with the trends to *only* publish specs at 10khz and higher, how are we to even from an educated guess (aside from trusting our ears, which gets expensive...)
Quote:

Originally Posted by Pars /img/forum/go_quote.gif That would be replacing R20 (the 2 Mills resistors in bottom photo are R20 and other ch. R20)? Sorry, toob noob somewhat (can't even reference plate to the schematic part, etc. other than heaters ). I just assumed that is where a CCS would go...

yes, R20 should (if you want to...) be replaced with a CCS.
Quote:

Also, am I viewing this right as a high pass filter? For example, C8/R17 forms a filter with a -3dB point of 1/2 * Pi * 100000 * 0.000008 = .19Hz versus if I went 1uf it would be 1.59Hz?

yes, C8&R17 form a high pass filter.

C10, and whatever you are driving also from a high pass filter.

To kind of agree with davitisk's points before on high-pass filters cut-off-points even though i think the whole thing is still a little overblown, I have seen a couple recommendations to only have 1 filter ANYWHERE near 20hz in the system, as multiple "crossovers" in the same area can cause a smear. cathode bypass caps can have an effect, interstage coupling caps, etc. The idea dosnt seem so far-fetched to me, and in this case is not really all that difficult to execute.

 

[Pars]

Resistor selection for R17, R21 and an unmarked (and not shown on this schematic) resistor used for gain switching? If I were to replace/increase R17 from 100K to 500K, and wanted to replace the 1M R21 with another resistor type for lower noise, what would you recommend? The preamp stock uses Roederstein Resistas, which in general I like. In the altavista rebuilds, he uses some Caddock TF020s, the 1M R21 being one of them I can see from pics, and it wouldn't surprise me if R17 was one as well.

The gain resistor was a change from the SA5 to the SA5.1, and basically sits between the line/RIAA switch and the balance control (I ohmed it out and have it drawn in on a schematic copy around here somewhere). The preamp is noisier in the low gain position (resistor in circuit) than in the high gain position.

Any other resistor you would recommend? Tantalum? I will be ordering from partsconnexion, so might as well get those while they are 15% off as well.

 

[luvdunhill]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Any other resistor you would recommend? Tantalum? I will be ordering from partsconnexion, so might as well get those while they are 15% off as well.

It's strange, as I've been playing with a lot of resistors of late. In addition to the usual suspects, I'd like to recommend something a bit of the wall: Texas Components TX2352 or TX2575. I've compared them to the Vishay S102 and they are quite comparable. If you don't want to bother tracking these down (I buy direct), then I really like Caddock MK132.

edit:

data sheets, found under the "audio resistor" section of their website

http://www.texascomponents.com/pdf/tx2352.pdf
http://www.texascomponents.com/pdf/tx2575.pdf

 

[luvdunhill]

Quote:

Originally Posted by regal /img/forum/go_quote.gif Boutique at $2.50 each ?

yup.. I did some insane product comparison a while back looking for HV caps, and I think the best performing caps I found were some super expensive CDE caps (edit: these were "computer grade" caps... what the heck kinda computer needs 450v rails? they were like $25 for 10uF/450v) followed by the Xicon $2 caps. I choose the Xicon and put them in a HV power supply and was very impressed. Now, I was looking for 400V+ caps, but these two handily beat all other caps that I could get specs on. I think I compared around 50 'lytics.

I think I might have found the OEM for the Jensen caps, and they offer very competitive prices for custom caps and I have a bit out on some 600 VDC compatible caps.

 

[luvdunhill]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif As DIYers we look down on some brands of capacitors, and i'm stating to think that it's because the labels look dull.

well-said.

 

[Pars]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif It's strange, as I've been playing with a lot of resistors of late. In addition to the usual suspects, I'd like to recommend something a bit of the wall: Texas Components TX2352 or TX2575. I've compared them to the Vishay S102 and they are quite comparable. If you don't want to bother tracking these down (I buy direct), then I really like Caddock MK132. edit: data sheets, found under the "audio resistor" section of their website http://www.texascomponents.com/pdf/tx2352.pdf http://www.texascomponents.com/pdf/tx2575.pdf

Hi Marc,

Roughly what do these run? You must have added the pdf links while I was reading... I had gone to the site and looked at these. Looks like the resistance range doesn't go high enough (tx2352 goes to 250K). Unless I were to change out the 1M for something lower (and quieter). It appears that I could also change R21 (the 1M) as it is in parallel with the tube output impedance, which probably dominates.

I think Elliot now uses naked vishays (are those the S102s?) instead of the Caddock TF020s. You like the MK132s? Those go up to 1M or higher, and partsconnexion has them for ~$5+ each. WHich is better than the TF-020 1M at $11.

 

[Pars]

Quote:

Originally Posted by ericj /img/forum/go_quote.gif As DIYers we look down on some brands of capacitors, and i'm stating to think that it's because the labels look dull.

Pretty cap labels do have a large effect on "desirability"... good point.

 

[luvdunhill]

Quote:

Originally Posted by Pars /img/forum/go_quote.gif Hi Marc, Roughly what do these run? You must have added the pdf links while I was reading... I had gone to the site and looked at these. Looks like the resistance range doesn't go high enough (tx2352 goes to 250K). Unless I were to change out the 1M for something lower (and quieter). It appears that I could also change R21 (the 1M) as it is in parallel with the tube output impedance, which probably dominates. I think Elliot now uses naked vishays (are those the S102s?) instead of the Caddock TF020s. You like the MK132s? Those go up to 1M or higher, and partsconnexion has them for ~$5+ each. WHich is better than the TF-020 1M at $11.

Well, the TF020s are physically larger and have lower power ratings than the S102. Honestly, I haven't never had a chance to use the TF020, 'cause of these two "limitations". If you buy the S102 from Percy, most of his have the casing removed. Percy also sells a cheaper Vishay bulk foil (VSH is it? it's almost like a footnote to the S102 section) and the prices are comparable to MK132. I haven't tried these yet. FWIW, Percy gets his Vishays from Texas Components, and I'm not really sure what the difference is between the Vishay S102 and the TXxxxx parts. Since Texas Components OEMs these resistors for Vishay, the line is even blurrier. With regards to pricing and this confusion, here's a good link:

diyAudio Forums - Is it worthwhile to buy Bulk Metal Resistors?

 

[rds]

I can sell you some resistors at $100 a piece, and when you're trying to figure out how you'll pay the rent you'll swear they are the best resistors you have ever heard.

 

[regal]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif I think I might have found the OEM for the Jensen caps, and they offer very competitive prices for custom caps and I have a bit out on some 600 VDC compatible caps.

Do you know the OEM for the Jensen 100+100/500VDC ?

 

[Pars]

Quote:

Originally Posted by rds /img/forum/go_quote.gif I can sell you some resistors at $100 a piece, and when you're trying to figure out how you'll pay the rent you'll swear they are the best resistors you have ever heard.

???

Good stuff...

 

[luvdunhill]

Quote:

Originally Posted by rds /img/forum/go_quote.gif I can sell you some resistors at $100 a piece, and when you're trying to figure out how you'll pay the rent you'll swear they are the best resistors you have ever heard.

I'm thinking about making my own resistors for I/V duty. I need around 50 feet of silver wire... they'd be much more than $100 each.

Is this what you're referring to?

 

[nikongod]

I dont think that R17&21 are particularly significant to the sound. they should be good, but dont have to be great.

R18,19,30 should of course be great

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif I'm thinking about making my own resistors for I/V duty. I need around 50 feet of silver wire... they'd be much more than $100 each.

resistor loading an I/V stage? Or resistors in an active I/V stage?

 

[luvdunhill]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif I dont think that R17&21 are particularly significant to the sound. they should be good, but dont have to be great. R18,19,30 should of course be great resistor loading an I/V stage? Or resistors in an active I/V stage?

the former.

DIY resistors are the new Singlepower... says me. Just a major PITA to wind.

BTW, I figured out that the resistors Percy sell are the TX2352... says so on my invoice at least. Who woulda thunk. I guess they do indeed sound very favorable.... as in, pretty much identical. Silly me.

 

[rds]

Quote:

I'm thinking about making my own resistors for I/V duty. I need around 50 feet of silver wire... they'd be much more than $100 each. Is this what you're referring to?

Yeah