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OLD THREAD Hi-end phono preamplifier by Andrea Ciuffoli

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#342
Phono/Regulator PCB

Hooray!!!!!!!!
My boards arrived today 16th September. They are the ones posted 07/09/10.
Very high quality boards, Quanghao is to be complimented on them, excellent.

I see from an earlier post that ideally the second RIAA capacitor should be 4600pF and that 4700pF is near.
I am using Silver Mica 1% capacitors from Farnell of the following values and part Nrs.
C13-15/C25-27 = 13.5nF = 3 x 3,600pf +1 x 2,700pF in parallel = 13.5nF = 13,500pF
C10-12/C22-24 = 4600pF =1 x 3600pF + 1 x 1000pF in parallel = 4600pF

Farnell UK part numbers
1000pF - Pt Nr. 126-4890 £ 1.60 = £ 1.88 inc VAT (1-50)
2700pF - Pt Nr. 126-4899 £ 2.30 = £ 2.70 inc VAT (1-50)
3600pF - Pt Nr. 126-4900 £ 2.66 = £ 3.13 inc VAT (1-50)
4700pF - Pt Nr. 126-4901 £ 2.66 = £ 3.13 inc VAT (1-50)

For those of you that do not have access to someone like Farnell I would be prepared to do a bulk buy and distribute accordingly.
Cost would be Farnell price plus VAT plus postage. I would expect postage to be low ie £2.00/€3.00/$3.00 as these things do not weigh much. If interested please pm me.


I also think that Quanghao should be given a big vote of thanks for taking on this job especially as English is not his prime language, and he has had to understand our abbreviations and colloquialisms.

Well done.

John Caswell
 
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#345
Phono/Regulator PCB

Hi Jezza,
Well yes 4600pF is not a standard E** value whereas 4700pF is a standard value so 4600pF is not made, similarly 13n5F (13,500pF) is also not a standard value so it is relatively easy to make them up using standard values from the E12/E24 ranges.
These ranges have been devised such that say 4K7 +10% will be within the 5K6 - 10% limits therefore any resistor made to +/- 10% tolerance has to fall in either the lower limit of the next value higher or the upper limit of the next lower value. These rules apply to all of the E** ranges only the tolerance varies therefore the number of Rs or Cs in the ranges increases as the tolerance decreases hence +/- 1.0% resistors/capacitors come in E96 range, ie 96 vstandard values
However in practice resistors follow, say, the E96 range values but capacitors rarely exist outside the E12 series ie 1.0, 1.2,1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2 and back to 1.0 but a decade higher.

John Caswell
 
#348
I have designed an enclosure for this preamp.

I will post more pictures of assembly when I get the metal back net week 🙂

This will house both pc boards and an alps slider potentiometer.

The open sides will be closed with wood.
 

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#350
John Caswell said:
Hi Jezza,
Well yes 4600pF is not a standard E** value whereas 4700pF is a standard value so 4600pF is not made, similarly 13n5F (13,500pF) is also not a standard value so it is relatively easy to make them up using standard values from the E12/E24 ranges.
These ranges have been devised such that say 4K7 +10% will be within the 5K6 - 10% limits therefore any resistor made to +/- 10% tolerance has to fall in either the lower limit of the next value higher or the upper limit of the next lower value. These rules apply to all of the E** ranges only the tolerance varies therefore the number of Rs or Cs in the ranges increases as the tolerance decreases hence +/- 1.0% resistors/capacitors come in E96 range, ie 96 vstandard values
However in practice resistors follow, say, the E96 range values but capacitors rarely exist outside the E12 series ie 1.0, 1.2,1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2 and back to 1.0 but a decade higher.

John Caswell
Click to expand...

Thank you for understanding my language problem!

PM: You have received the PCB's I sent?
 
#352
Phono/Regulator PCB

Hi Quanghao and others,
Yes I have received the PCBs as I said, and am in the process of building them, but other work keeps getting in the way and the need to earn money is very high at present.
I am initially just going to build the phono stage as I already have a PSU that will be suitable. My idea is to put it in a diecast Hammond box at first to sort out any assembly/wiring/component problems and then get a custom enclosure made by a friend as I will need to add some moving coil step up txs probably Sowter 8055s. Hopefully will take some pictures and put them up here.

Regards

John
 
#353
klaju1955 said:
looks great Tang, very professional, I´m looking forward for see it finished.

Klaus
Click to expand...

Thanks! ,here is the latest progress , Got the metalwork yesterday. All my previous projects I used natural anodized Alu , but for this one I tried brushed 430 Stainless steel:
 

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#355
Hello all,

I am starting to build mine. Yes I know it is almost a year after the PCBs have been made, but you know not enough time, small kids and all 🙁

I see there are some errors on the board that have been found, and also that there are two versions of RIAA corrections. Quandhao, would you be so kind to post the last schematic for RIAA and regulator please, so that I am sure on what I am to build. Also would you post in the same place where to take care on errors of the PCB.

Thank you in advance,
Pred
 
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