OK, I completed building the Isotope phono preamp with kit received from doors666.
No hiss, hum or any funny noise. I didn't even bother to use grounding wire from the TT to phono preamp.
I've briefly tried NE5532, LME49990 (using single to dual adapter) and AD823. I haven't listened enough to decide which opamp I like the most, but planning to roll some more (like OPA2134).
But one thing seems already clear - this is a very good sounding phono stage. It does "dehomogenisation" very well in that it separates the various musical strands/voices/instruments beautifully, making it very effortless to follow the strands of music. This results in specific placement of voices and instruments in the sound stage, imparting a very holographic sound stage.
I'm yet to compare it with my other phono preamp (a Pearl 2 clone). I'll do so in due course when I've put in more hours. I'll also try pitting it against my other phono preamp (MC-only, Hypnotoad) using a step up.
I deviated a bit from the stock circuit to take care of cartridge loading (high output MC with 160 Ohms internal impedance). I've also increased gain slightly as I felt it was low for my unity gain Kuartlotron buffer. I've also reduced the DC supply voltage to about +/-15.x Volts as higher voltage resulted in over heated opamps. Thanks to doors666 for guiding and handholding me to tailor the circuit to my needs.
PS: if buying the kit from the designer, make sure you don't mix up the RIAA capacitors and resistors packed separately for each channel as they are carefully matched.
No hiss, hum or any funny noise. I didn't even bother to use grounding wire from the TT to phono preamp.
I've briefly tried NE5532, LME49990 (using single to dual adapter) and AD823. I haven't listened enough to decide which opamp I like the most, but planning to roll some more (like OPA2134).
But one thing seems already clear - this is a very good sounding phono stage. It does "dehomogenisation" very well in that it separates the various musical strands/voices/instruments beautifully, making it very effortless to follow the strands of music. This results in specific placement of voices and instruments in the sound stage, imparting a very holographic sound stage.
I'm yet to compare it with my other phono preamp (a Pearl 2 clone). I'll do so in due course when I've put in more hours. I'll also try pitting it against my other phono preamp (MC-only, Hypnotoad) using a step up.
I deviated a bit from the stock circuit to take care of cartridge loading (high output MC with 160 Ohms internal impedance). I've also increased gain slightly as I felt it was low for my unity gain Kuartlotron buffer. I've also reduced the DC supply voltage to about +/-15.x Volts as higher voltage resulted in over heated opamps. Thanks to doors666 for guiding and handholding me to tailor the circuit to my needs.
PS: if buying the kit from the designer, make sure you don't mix up the RIAA capacitors and resistors packed separately for each channel as they are carefully matched.
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Some build pics:
The Isotope board:
Board populated:
Blues Piwrr Mini Shunt Regulated Power Supply board:
PS board populated:
Putting it together:
Face plate:
The Isotope board:
Board populated:
Blues Piwrr Mini Shunt Regulated Power Supply board:
PS board populated:
Putting it together:
Face plate:
I bought the boards for the Isotope preamp and shunt power supply a month or so ago. I was waiting for a suitable cigar box to show up but so far nothing has inspired me.
I soldered together the boards a couple of weeks ago. Yesterday I ran out of patience and grabbed an old Control4 controller box, ripped the circuit board out of it, cut some heat sink and cobbled together the preamp. I know, it looks like crap, but I was in a hurry.
This is such a musical preamp! Even in it's thrown together state it is dead silent. The music just strikes me as realistic and so enjoyable. I don't think it worth the effort to wax poetic and throw out a bunch of superlatives. I am thrilled with it and count it as a true bargain. It was simple to build and door666 was a joy to deal with.
Take into account that I am comparing this to a humble NAD PP3 preamp.
I soldered together the boards a couple of weeks ago. Yesterday I ran out of patience and grabbed an old Control4 controller box, ripped the circuit board out of it, cut some heat sink and cobbled together the preamp. I know, it looks like crap, but I was in a hurry.
This is such a musical preamp! Even in it's thrown together state it is dead silent. The music just strikes me as realistic and so enjoyable. I don't think it worth the effort to wax poetic and throw out a bunch of superlatives. I am thrilled with it and count it as a true bargain. It was simple to build and door666 was a joy to deal with.
Take into account that I am comparing this to a humble NAD PP3 preamp.
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