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Old 18th July 2010, 05:35 PM   #4181
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Hello, first of all I have to say a big thank you to Salas for his great work and his even greater help.

I am planning to build the phono stage and I have some questions about the capacitors.
I have already ordered some obbligatto caps, but for higher values there aren't any. The values I can't find are 220uf 25v, and 100uf 65v.
Are there any suggestions for them? Similar quality with the obbligatto would be ideal.
And also for the 15.1nf cap I found a 15nf and a 0.1nf from Jensen but they cost about 80 euro in total.
Do we have any suggestions about them too?

And if possible the shops I can buy them
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Old 18th July 2010, 05:56 PM   #4182
Salas is offline Salas  Greece
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100 & 220 uF are electrolytics obviously. You are obligated to skip obbligatto.
Get some KMH, FC, etc. and you are done, they are not doing signal.
15nF caps will vary on an LCR meter. Some will be 15.1nF. Still 15nF spot on will be a tad brighter but will do. Most overshoot or undershoot for tolerances.
My suggestion is you go buy plain vanilla MKP caps of small sizes so you can control your layout, and when you will know how to make a noiseless high gain circuit silently so for hum in practice, then spend on parts you fancy by making it from scratch in more wit and wisdom. If you start with expensive parts without having made it before its highly possible you will end up destroying more of them legs in experiments or not knowing how to fit them. Tight layout adds detail. Just my 2C.
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Old 19th July 2010, 10:28 AM   #4183
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Quote:
Originally Posted by stelakis1 View Post
Hello, first of all I have to say a big thank you to Salas for his great work and his even greater help.

I am planning to build the phono stage and I have some questions about the capacitors.
I have already ordered some obbligatto caps, but for higher values there aren't any. The values I can't find are 220uf 25v, and 100uf 65v.
Are there any suggestions for them? Similar quality with the obbligatto would be ideal.
And also for the 15.1nf cap I found a 15nf and a 0.1nf from Jensen but they cost about 80 euro in total.
Do we have any suggestions about them too?

And if possible the shops I can buy them
As sugested by Salas 1st fix the less hum with maximum gain with cheap components & when you know exact values post it & I will let you know where to buy.
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Old 19th July 2010, 11:06 PM   #4184
psgr is offline psgr  United States
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Hi Stelakis,

there is a ebay resaler who also sales through his web site, his url is : rutubes.com.
Write to him he will sell you 2 of each of the film caps that you need. He has silver mica (14.7nf,14.8nf,46nf)and the teflon FT3-100nf. He also has some smaller values, that you will need to add to the above caps to reach the desired values.
You have nothing to loose by asking him for a quote.
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Old 22nd July 2010, 06:31 AM   #4185
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Thank you all for the help.

I decided to buy cheap components at first to give it a go (hopefully in the weekend I will have it ready, I found everything in local shops) and then if everything goes right move to "exotic" parts.

rutubes... nice! Thank you very much psgr!

@Merlin

Muchas gracias mi amigo, when I finish the first silent "prototype" I'll contact you for sure.
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Old 27th July 2010, 01:04 PM   #4186
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I am building the 56dB gain version. For that I will need 37Volts of regulated DC using the Salas Shunt regulator. I will use a seperate shunt regulator for each channel.

I need to verify my understanding of the regulator regarding the current it would consume.

If I sum the currents in the regulator I find that it will use about 157mA.
I assume that Q2 will pass 6-7mA and Q1 will pass 150mA approximately.

Q4 will then pass about 135 to 140mA.

Is it critical to have the regulator set up for remote sense?
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Old 27th July 2010, 02:30 PM   #4187
Salas is offline Salas  Greece
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Do you have proper IDSS fets by now? What IDSS pairs you got? You will need more dB for low MC.

Remote sense is highly desireable. Don't skip it.
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Old 27th July 2010, 04:46 PM   #4188
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I will be determining IDSS tonight. Have 30 2sk177BL's to play with.
I will incorporate remote sense as it is an easy change in the pcb I designed.
The Power Supply for the shunt regulator can provide up to 49Volts with a RCLC filter. I was curious about the current to get the R in the ball park. The trany is from a previously abandoned project is an Avel Torroidal and has two secondaries of 18V which I was going to stack giving 36VAC. It is overkill but I have it on hand.

I'll post the IDSS tonight when I get the measurements completed.

PS I have around 5dB gain in my linestage available.
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Old 27th July 2010, 05:22 PM   #4189
Salas is offline Salas  Greece
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We run about 150-200mA idle current on each shunt so to keep the Mosfets awake.

After you do the 170BL sorting we will see how we will use them best. I will cook one tuned for your fets and cart.
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Old 27th July 2010, 06:06 PM   #4190
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Thanks. WIll get back to you shortly.

Until then, is this reasonable for the shunt regulator with remote sense?
Attached Images
File Type: png ShuntSchema with sense.png (14.8 KB, 187 views)
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Last edited by SGregory; 27th July 2010 at 06:22 PM.
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