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Phono board options

How do you want the functionality split up

  • Four small boards

    Votes: 6 18.2%

  • Two boards, each a complete channel

    Votes: 13 39.4%

  • Two boards, stereo front end and stereo EQ

    Votes: 1 3.0%

  • One big board

    Votes: 11 33.3%

  • Don't care

    Votes: 2 6.1%
  • Total voters
    33
  • Poll closed .
Hi Gareth,

Many thanks for the offer. RS did respond to my question and they will export, however, they have listed the 197-9840 part as no longer manufactured with only 4 left in stock. I am ordering them and will see if that works. If not, I'll be in touch.

Cheers

Martin
 
Dalbani in the UK came through, I managed to order a few of the 2SC2547 and 2SA1085 variants. RS tell me that the 2SC2547 is now discontinued and seem to have 'lost' the 4 in stock so my advice to anyone considering building PD's design should snap up some of the remaining stock at Delbani before it's to late.

Now back to circuit layout unless Sharif beats me to it!

Regards
 
Mmmmm I think I have a few of both lying round, let me dig them out and see how many I have I was going to re-pop my naim boards with them but sold those long ago.
 
I have some spare stock as well; I'll look in my parts drawer when I get home.

I'm deeply annoyed that these have gone obsolete; I don't know of another device that is remotely comparable. The combination of very low voltage noise, very high gain, tiny 1/f noise and acceptable capacitance is/was unique.
 
Seems odd that a part that is so unique is discontinued (and you are right these seems to be absolutely no equivalent). Unfortunalely I expect that we will see that with a lot of our favorite discreet components over the next few years.
 
I'll have a look, but the Hitachi parts were made by a special epi process, and I doubt anybody else can imitate it.

Let me see.

On the positive side, for MM use, BC550/560 is a fine alternative; the very low voltage noise is not needed, as the Johnson noise from the much higher source impedance dominates anyhow, and there is the option of the JFET circuit as well.
 
audioflyer said:
Could the BC327-40-BK and BC337-40-BK be an option?
Click to expand...

I have looked at about 6 datasheets, but none of them have noise measurements.

It seems a perfectly nice average small signal device - why do you think it is low noise? Have you seen measurements somewhere?
 
PigletsDad said:
I have looked at about 6 datasheets, but none of them have noise measurements.

It seems a perfectly nice average small signal device - why do you think it is low noise? Have you seen measurements somewhere?
Click to expand...



I've just look through my old transistor data books and none have any noise measurements.
My reason for suggesting them was that they have a low rbb but not as low as the 2SC2547 and 2SA1085.
 
Would it be possible to use 2SC3329 for the NPN? There's a seller on ebay flogging these cheap at 20 per pack. I can't find the matching PNP though.
 
Now that looks more promising. Rbb is claimed 2Ohms! And at high currents (say 5mA) the total noise is comparable to a 15Ohm resistor - about 0.6nV/rtHz.

Where it falls down, and the Hitachi part was so remarkable, is in the 1/f region. At 10Hz, it looks more like 200Ohms worth of noise. Now the ear is not sensitive to quiet low frequency noises, but the the RIAA curve boosts the bass by 20dB, so 1/f comes back into view as a concern.

As you say, the real problem would be finding a matching PNP.
 
OK, the suggested complement is 2sa1316. Lets see if these are in production.

Digikey, Mouser, Farnell and RS all draw a blank.

Cricklewood have heard of 1085/2547, but not 1316/3329

Dalbani have some of all.

I fear we are substituting one unobtainable part with another.
 
audioflyer said:
I may have found something.

New device at Mouser Electronics 2SA1312 and 2SC3324.

http://www.toshiba.com/taec/components2/Datasheet_Sync//50/6505.pdf

http://www.semicon.toshiba.co.jp/docs/datasheet/en/Transistor/2SC3324_en_datasheet_071101.pdf
Click to expand...

Close, but no cigar!

The white noise in the PNP is too high - about 1nV/rt Hz. The NPN white noise is good, but not great (round about 0.65nV/rt Hz), and for both of them the 1/f noise is terrible, although that may not be so audible.

Surface mount packages are challenging for many DIYers, although clearly through lead components are getting fewer and fewer.
 
I'm probably being a bit unobservant, but is the full schematic available on the thread anywhere. I'll be needing a phono stage in the near future and was hoping to use this.

Cheers

Mike
 
PigletsDad said:
Now that looks more promising. Rbb is claimed 2Ohms! And at high currents (say 5mA) the total noise is comparable to a 15Ohm resistor - about 0.6nV/rtHz.

Where it falls down, and the Hitachi part was so remarkable, is in the 1/f region. At 10Hz, it looks more like 200Ohms worth of noise. Now the ear is not sensitive to quiet low frequency noises, but the the RIAA curve boosts the bass by 20dB, so 1/f comes back into view as a concern.

As you say, the real problem would be finding a matching PNP.
Click to expand...

Alternatively we could try Les's old favourite combination of 2SD786/2SB737. There looks to be a few supplies still hanging around.

I replaced the 5 NPN banks in a set of Naim MC cards with 2SD786s, plus Dale RN55, 15R base resistors, they do sound very good and very quiet!
 
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