Good Phono Pre for Pioneer SX990

[Paul McShart]

Hey I was just wondering if any of you guys can direct me in the right direction with getting a dedicated phono pre for this stereo. My turntable is a Technic Sl-1700 and speakers are ADS l620s.

I know the pioneer isn't very high wattage but I'd love to keep it as its passed down from my dad and its very sentimental to me...also I think it sounds great when using the aux. The reason I need a phono stage is because ever since I've been using it, the phono stage is unbearably noisy (think it's prolly bad transistors and prolly due for a recap).

Anyway, since I've gotten into vinyl this past year, ive been using a Pyle Pre-amp (haha ik, not the best) and would love to upgrade.

Also, should I just have a tech completely go through the pioneer and fix the phono stages? Or is the phono stage not that great and would my system better benefit from a dedicated phono pre?

 

[Paul McShart]

Oh also have an old Grado cartridge which says x2 +. Cant really find anything on it, but its brown and gold

 

[Hoytis]

What's your budget? There are a ton of phone preamps out there. I've been using the Vincent PHO-701 and love it, nice and warm.

You're cartridge photo isn't showing for me, but Grado x2 is very good. How long have you had it? Might want to think about putting some money into a newer stylus as well. I wouldn't bother fixing the phono stage on that amp...but that's just me with no sentimental attachment...just crunching numbers.

 

[Paul McShart]

Thanks for the reply. Looking for something probably under $200.

And I've had the Grado since I got the tt in 2016. But I haven't really started to play records since this year. I can't remember if it came with a new stylus when I bought it ... to me it sounds ok but youre right, I should prolly get a new stylus to make sure. Do you know which stylus I can buy?

And yeah, I figured the phono stage isn't very good on the pioneer, figured a dedicated phono pre would get the job done better

 

[gadget73]

I have an Allied with that same phono board. I re-capped it and replaced the transistors and its much less noisy than it used to be. Not really a difficult job if you're up for a bit of soldering. This is the parts list I used to overhaul that board

Head Amp W15-049 SX-990 / Allied 495
p/n uf v Mouser p/n
C1 10 10 647-UKL1C100MDDANA
C2 10 10 647-UKL1C100MDDANA
C5 100 6 647-UKL1C101MPDANA
C6 100 6 647-UKL1C101MPDANA
C13 10 15 647-UKL1C100MDDANA
C14 10 15 647-UKL1C100MDDANA
C15 10 15 647-UKL1C100MDDANA
C16 10 15 647-UKL1C100MDDANA
C17 47 25 647-UPX1V470MPD

Transistors
p/n original new p/n
Q1 2SC458 512-KSC1845FTA
Q2 2SC458 512-KSC1845FTA
Q3 2SC458 512-KSC1845FTA
Q4 2SC458 512-KSC1845FTA
Q5 2SC458 512-KSC1845FTA
Q6 2SC458 512-KSC1845FTA

Possible that swapping the resistors out for metal film will drop the noise further, but thats purely a hunch.

 

[Paul McShart]

Hey thanks for the reply! My soldering skill isn't too good (only done electronics in my guitars which is super easy) but maybe I'll give it try..really appreciate you listing all the parts!

 

[gadget73]

yeah the boards are not the most robust, so I would suggest being careful. Its typical early PCB stuff, the traces will lift if over-heated or abused.

Most of my Allied is the same as the SX-990, only real difference is the power amp is good for about double the wattage. Overall sound should be very much the same. Its a nice sounding thing, though maybe not the most accurate. I've had mine for better than 20 years at this point.

 

[Okke 70s]

Possible that swapping the resistors out for metal film will drop the noise further, but thats purely a hunch.

Done that recently with a basic phone-stage that still was a bit dull and noisy to me. Even after new quality caps and 1845's. The metal film resistors made a considerable improvement.

Edit: only did those 4 in the signal path.

 

[Fitzer]

Food for thought, if your budget for a phono preamp is $200, that would likely very easily cover the cost of a tech going in and recapping/servicing the phono stage of your receiver, along with general maintenance like blowing out old dust and deoxit on the controls. Worth looking into.

If no local tech is available, go to goodwill and buy some crappy old electronic component for 10 bucks and practice soldering/desoldering on the PCBs. You’ll get a feel for it pretty easily and you can damage traces without fear as you practice. Just get some good quality solder wick—I’ve done some major jobs with just a roll of NTE solder wick and an old Weller iron.

 

[gadget73]

Done that recently with a basic phone-stage that still was a bit dull and noisy to me. Even after new quality caps and 1845's. The metal film resistors made a considerable improvement.

Edit: only did those 4 in the signal path.

Thanks for that. If I ever put this thing back into service where it actually has a turntable connected I'll do that. Its my shop radio at work these days, so pretty much so long as the tuner works the rest doesn't matter.

I actually do have one of these boards from the parts hulk. I should power it and do some noise level measurements on it as-is, with new caps, with new transistors, and finally with new resistors where appropriate just to see what it does. I did a re-resistor on the playback amps in my old Sony reel to reel and got a huge drop in background noise level, so it wouldn't surprise me to get results out of a phono stage. They're not that different in terms of signal level and gain.