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Versatile and comfortable passive pre-amp

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#823
Many many thanks for all your hard work, I know it's been some journey!!

I still haven't assembled my preamp...😱😱 as I like to get everything together first before starting.

I have won a Bang & Olufsen Beocord 5000 on e-bay which I hope will make a nice box for it, with some "adjustments". I was looking for a faulty hi-end pre-amp so I could have the nice box and the connectors already, but all the ones I saw were either not particularly good metalwork or too much money.

Someone on here had a very very nice case and I may upgrade to that later, if I can source it somewhere where it can be delivered to the UK. Always seems to be difficult to find a nice case. I was lucky with my power amp as I found a reasonable looking satin black computer case with a whole front which hinges down and a single power button on the bottom.

For the Nelson Pass buffer, who can supply the quad matched 2SK170BLs? I saw someone offering them on here but can't seem to find the thread now.
 
#827
Here we are:

Myint67: you are No. 1
Fabian85: you are No. 2
Aradan: you are No. 3
Speakert: you are No. 4

I do not have any more RPRE-PCBs! So: please do not subscribe to this offer!

Just finished mine, sounds awesome - like nothing is in between the speakers and the recording studio :sax::eguitar::

I know this, Taco! The LDR attenuation being followed by Mr. Pass' buffer is a perfect team!

I will send a PM to you four this afternoon!

Best regards - Rudi_Ratlos
 
#830
anjump123 said:
Found the case on ebay.

Now just need to source the 2SK170BLs, anyone?

Are these likely to be fake?

MATCHED QUAD OF TOSHIBA 2SK170 2SK170BL 2SJ74 2SJ74BL AUDIO FET | eBay

Or these

2SK170 2SK170BL Toshiba matched Quad | eBay
Click to expand...
I have LSK170A & C grade in swap meet for UK buyers.

I've not been reading this Thread.
Are these matched quads, or just selected Idss quads.

You will find it virtually impossible to get matched quads from anyone.
I managed to get lots of matched pairs from my 600off LSKs.

Selected Idss are easy, but not the same.
 
#831
Rudi,

Thanks very much, just placed an order form your recommendation.

Andrew,

Doh!
I hope the seller I bought from is good.

Google translation. "2SK170BL Toshiba matched quad (4 pieces)

The transistors are only measured with a MOSFET Analyser .

It is measured with the RDS , the threshold voltage and Id at threshold ."

Got to admit not entirely clear what that means but if it's good enough for Rudi then I won't be disappointed.

If not I will be touch.
 
#837
Then selected Idss is plenty good enough.

Just measure a group and select two that have the same Idss. Then select a second pair for the other channel.

The B1 does not need matched jFETs.

I sold out of matched lsk170b, yet most were for B1 builds. I kept telling my intending customers they did not need to waste matched jFETs on a B1 build. But the customer is always right. I sold to them anyway.
I sold out mainly because I undercut virtually any other seller at the prices I still offer for A & C grade.

Matched jFETs are required for an LTP at the front end of a power amp, or discrete opamp.
 
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