General Forum

Re: B&O SP12 pickup replacement options?

chartz — Sun, 29 Jan 2012 09:55:44 GMT

Great job then!

Re: B&O SP12 pickup replacement options?

gjaky — Sun, 29 Jan 2012 09:40:12 GMT

I was also amazed by the sony receiver, but it sounded just as it should instead of my BC3500. Also I had a BM3000-2 which sounded ok with a cheap TESLA turntable, but this BC doesn't impressed me with the same record, so probably the problem is unique to this specimen. I measured all parts in the phono preamp, but only found 3 resistors which were slightly out of specs (but they doesn't affected the equalization -in theory at least)

For the RIAA curve: I found that the real problem (in my case) is that there is too much bass coming from the BC (instead of lack of highs), and the mid area isn't flat enough, so this mod I did only flattens a bit more the mid area (200-5000Hz).

I did a computer simulation for the circuits, the reference was the REVOX A78's RIAA, and the theoretic RIAA curve.

Re: B&O SP12 pickup replacement options?

chartz — Sun, 29 Jan 2012 08:45:37 GMT

Hi,

That's weird.

I haven't modified the RIAA filter circuit in my BC3500 and the phono has plenty of treble.

I just followed Tim Jarman's advice and replaced C346/378 (1nF) with 100pF to brighten things a little bit. He also explains this in the latest Hi-Fi World issue.

I wouldn't be too trusty about the Sony thingy, and what you did was in effect modifying the RIAA curve to cut less treble. Can't be right!

Re: B&O SP12 pickup replacement options?

gjaky — Sun, 29 Jan 2012 08:17:36 GMT

Problem solved... Accidentally I got a sony home theater receiver for testing and I hooked up it's phono input with my bc3500's turntable, and the difference was very-very notable. So I digged myself into the BC's phono preamp and found the way to make it better. I replaced the resitor 347, 385 to 33kOhm and capacitor 348, 384 to 2nF (2*1nF in parallel, but probably a single 2,2nF will do the job too)

Re: B&O SP12 pickup replacement options?

gjaky — Tue, 17 Jan 2012 14:52:45 GMT

Ok, it seems the major problem is that the speed of the plate is too low instead of a worn-out pick up. I've tested the stroboscope sign: it isn't "stopping", and compared a track from a record with an mp3, and the record was notably slower, thus lower pitch.

The question is now how to set the right speed? The +/- signed knob does nothing just engage/release the drive mechanics, the belt is in ok condition.

Any help will be appreciated.

Re: B&O SP12 pickup replacement options?

chartz — Thu, 05 Jan 2012 01:57:15 GMT

Hi,

I can confirm this, my Beocenter 3500 has a re-tipped SP12 and it does sound fantastic. My rectifier also had two bad diodes! The SP14 is not as good. The treble thing: don't forget that most radio stations will have a tweaked frequency response to raise treble, typically for car use. I even find differences in sound quality with different transmitters for the same stations!

Re: B&O SP12 pickup replacement options?

Doctor — Wed, 04 Jan 2012 17:31:18 GMT

Get Axel to re-tip it - the SP12 is the one to have.

B&O SP12 pickup replacement options?

gjaky — Wed, 04 Jan 2012 13:31:54 GMT

Hi,

I picked up a faulty BC3500 for free, fortunatly the machine is in fantastic optical condition, after replacing the main rectifier the set is working fine. However the pickup of the turntable is probably worn out, this set is equipped with SP12 pickup, the high frequency reproduction of the pickup is rather poor compared to even the FM radio, I need to turn up the treble to about 2-3 to get enough treble with the turntable. Is there any BUDGET option for replacing the stylus or the whole pickup? (the stock ebay prices are too high for me) How performs the SP14 pickup compared to the SP12?