The issue with parallel diodes is they are never that well matched, so one will always be doing a bit more of the work than the other, at times.
Aaaah! So it isn't really an issue of sound quality at all but simply sub-optimal design. i.e. 3A + 3A does not equal 6A.richie00boy said:
I still like my idea though! 🙂 Surely both diodes will not conduct at EXACTLY the same time? I suppose the effects would be negligible.
Sonusthree said:
Please say I'm right. I will then claim this 'new' discovery as mine and call it Temporal Diodic Aberration.
I will remove the extra diodes tonight!!
Cheers,
Martin.😀
Buzzing PSX
First post - Sorry to hijack this very interesting thread. I've owned Cyrus 2 and PSX from new - bought them in 1992. Currently paired with original Mission 753s (yeah - its bright but I like it!) and fronted by a Arcam Alpha 7SE , Dual CS505-2 and a Cyrus T Tuner. I still love the sound after all these years.
The PSX itself has started buzzing - intermittently and quietly, varying in volume but clearly audible duirng quiet passages and when no music is played.
Any ideas what might be wrong. I'm no electronics expert but I'm handy with a soldering iron and multimeter. If its the toroidal then I guess that the expensive bit?
Thanks
Pete
ps I thought the phono stage was dead but thanks to this forum I realised that I needed to power the Cyrus 2 as well as the PSX. Muppet!
First post - Sorry to hijack this very interesting thread. I've owned Cyrus 2 and PSX from new - bought them in 1992. Currently paired with original Mission 753s (yeah - its bright but I like it!) and fronted by a Arcam Alpha 7SE , Dual CS505-2 and a Cyrus T Tuner. I still love the sound after all these years.
The PSX itself has started buzzing - intermittently and quietly, varying in volume but clearly audible duirng quiet passages and when no music is played.
Any ideas what might be wrong. I'm no electronics expert but I'm handy with a soldering iron and multimeter. If its the toroidal then I guess that the expensive bit?
Thanks
Pete
ps I thought the phono stage was dead but thanks to this forum I realised that I needed to power the Cyrus 2 as well as the PSX. Muppet!
Hi Pete, Welcome to the forum. 🙂
It would be very useful to know if the buzzing sound is coming from the PSX (mechanical noise) or through the speakers (electrical noise).
My PSX does make a reassuring low frequency hum but it's not audible when music is playing or I am not next to the PSX.
Hmmm ... sometimes the bolt that holds the toroid can become loose (never overtighten it though) and this can allow vibrations.
I have seen some massive PA amps where the transformer buzzes away loudly.
Would you describe the noise as a buzz (kind of raspy) or a low frequency hum? 🙂
It would be very useful to know if the buzzing sound is coming from the PSX (mechanical noise) or through the speakers (electrical noise).
My PSX does make a reassuring low frequency hum but it's not audible when music is playing or I am not next to the PSX.
Hmmm ... sometimes the bolt that holds the toroid can become loose (never overtighten it though) and this can allow vibrations.
I have seen some massive PA amps where the transformer buzzes away loudly.
Would you describe the noise as a buzz (kind of raspy) or a low frequency hum? 🙂
Its a mechanical noise from the PSX itself. Its not a hum - definitely a buzz. It varies in volume. I'll open the case, try tightening the transformer bolts and take some pics for you guys.
Cheers
Pete
Cheers
Pete
Hopefully tightening will do the trick. I would also test the diodes with the multimeter while you're in there.
The insides of the PSX are rather simple really ....
One circuit provides +/- 48V DC to the Cyrus 2 through the 'umbilical' cord . This just uses some caps and diodes. The resistors are there to 'bleed' the power from the large capacitors.
Another (seldomly used circuit in there has diodes, caps and two regulators (with heatsinks) specially for supplying an old Mission CD player (PCM11) with regulated DC, 18Volts I think?
Be careful with the voltage stored in those large capacitors. There are some resistors that slowly drain the current from them when the PSX is switched off so give it 20 minutes if you're unsure.
You're right. The Transformer is probably the most expensive thing in there. Although, the large caps would cost you a small fortune to replace with exactly the same type (slit foil).
The insides of the PSX are rather simple really ....
One circuit provides +/- 48V DC to the Cyrus 2 through the 'umbilical' cord . This just uses some caps and diodes. The resistors are there to 'bleed' the power from the large capacitors.
Another (seldomly used circuit in there has diodes, caps and two regulators (with heatsinks) specially for supplying an old Mission CD player (PCM11) with regulated DC, 18Volts I think?
Be careful with the voltage stored in those large capacitors. There are some resistors that slowly drain the current from them when the PSX is switched off so give it 20 minutes if you're unsure.
You're right. The Transformer is probably the most expensive thing in there. Although, the large caps would cost you a small fortune to replace with exactly the same type (slit foil).
Well - it was one of the two bolts holding the toroidal in place. I tightened that one up and now its silent again. Built by Nik apparently!
If anyone wants pictures - particularly of the fuses to remove from the Cyrus 2 to enable the PSX let me know. There is also interestingly a headphone socket connection on the PCB. The headphone socket was on early Cyrus 1 and 2 but removed from the later one to allegedly keep the signal path pure. Perhaps a mod if anyone is desperate not to upset the neighbours. I didn't try a set of phones against it.
Thanks anyway - I'll keep this site bookmarked!
Pete
If anyone wants pictures - particularly of the fuses to remove from the Cyrus 2 to enable the PSX let me know. There is also interestingly a headphone socket connection on the PCB. The headphone socket was on early Cyrus 1 and 2 but removed from the later one to allegedly keep the signal path pure. Perhaps a mod if anyone is desperate not to upset the neighbours. I didn't try a set of phones against it.
Thanks anyway - I'll keep this site bookmarked!
Pete
Nice one Pete!
Yeah the headphone socket doesn't mute the speakers which is a pain and makes it pretty much useless.
Even more so when you consider the risk of touching the red and black speaker connections together and blowing your amp just to use headphones.
Anyway, I bet your system sounds way better now that it doesn't hum AND you fixed it yourself. 😀
All the best,
Martin.
Yeah the headphone socket doesn't mute the speakers which is a pain and makes it pretty much useless.
Even more so when you consider the risk of touching the red and black speaker connections together and blowing your amp just to use headphones.
Anyway, I bet your system sounds way better now that it doesn't hum AND you fixed it yourself. 😀
All the best,
Martin.
Sonusthree said:
"Seldomly used circuit"? "Old Mission CD player"?
Cheek!
I'll have you know my Mission PCM II CD player is in the first flush of youth and is in regular use every day, fed with oodles of delicious clean power by this very frequently used circuit in my PSX...
😉
rwtomkins said:
Sorry! 😀 I was just trying to save time. I've always fancied owning one of those. It would be nice to hear a 'full' Cyrus line up. PCMII PSX and Cyrus one and/or two.
It looks like quite a simple regulated circuit that should be easy to DIY.
Do you notice a difference when using the PSX with the CD player?
All the best,
Martin.
Hello, sorry for my English, I'm from Russia.
I have Mission 767 and LFAU about 2 month. And week ago I bought PSX for LFAU. What I need to do with LFAU to make PSX work? Only remove two fuses inside of LFAU(it looks very similler to Cyrus 2 inside)?
Thanks
I have Mission 767 and LFAU about 2 month. And week ago I bought PSX for LFAU. What I need to do with LFAU to make PSX work? Only remove two fuses inside of LFAU(it looks very similler to Cyrus 2 inside)?
Thanks
I have never seen a LFAU so I can't be sure but yes, to connect a PSX to the Cyrus Two, all you do is remove the two glass fuses from the motherboard, so the procedure is probably the same.
is it a PSX or PSXr?
I think the r is intelligent and requires a signal from the load to switch it on and to set the output voltage.
I think the r is intelligent and requires a signal from the load to switch it on and to set the output voltage.
I'm assuming he's got the PSX, AndrewT. The PSX is compatible with the LFAU but the PSXr isn't - it's only compatible with later amps.
Hi Sonusthree, I see I never did reply to your last question about whether the PSX made much difference to the PCMII. I must admit I hardly ever listen to CDs - I'm nearly all vinyl - but the one time I tried it with and without, it didn't seem to me to make an obvious difference. It's more just a comfort thing of knowing I'm getting the best out of the player - plus, since the PSX is there, I may as well use it!