I just came on here to post the results of fitting new diodes myself. I just replaced D801-804 and D811-814 with 1.1A 100V Schottky diodes (Farnell part# 364-472) and a quick initial listen would suggest that the sound has changed for the better, particularly on transients and the feeling of "blackness" between notes and instruments.
Of course, this may not just be down the diodes. I'm half way through a batch of changes, so at the same time I've also replaced R601-606 with hand-matched 1% resistors and replaced Q811 (5V regulator) with a National Semiconductor LM340T-5.0.
Next up, I have a pair of OPA2134PA to fit, along with DIL sockets, but I need to find some desolder braid first. At the same time I'll replace RD21-28 with hand-matched 10k 1% resistors. Then it's time to listen to it!
I also have the parts for the separate 12V supply as recommended by disco so that's the next step.
Of course, this may not just be down the diodes. I'm half way through a batch of changes, so at the same time I've also replaced R601-606 with hand-matched 1% resistors and replaced Q811 (5V regulator) with a National Semiconductor LM340T-5.0.
Next up, I have a pair of OPA2134PA to fit, along with DIL sockets, but I need to find some desolder braid first. At the same time I'll replace RD21-28 with hand-matched 10k 1% resistors. Then it's time to listen to it!
I also have the parts for the separate 12V supply as recommended by disco so that's the next step.
Greg3333 said:
Schottky diodes have a lower forward voltage drop (resulting in reduced diode dissipation) than junction diodes. Most important property is their switching off cleanly without the current overshoot seen by junction diodes. This overshoot impulse excites resonances in the transformer-rectifier-reservoir cap system, leaving noise at the following regulator.
Most amplifier stages have poor isolation from garbage on the power rails (like noise) and as a result reproduction suffers from poor PSU quality.
If you'd like to experiment, solder 100 to 220nF/63V caps across each diode and have a listen for blackness of the background.
Regards, Jaap
disco said:
Or even better, do a little measure and math and then get it spot on.
http://www.hagtech.com/pdf/snubber.pdf
The 100-220nF value is quite probably universal in the sense it does have an effect. But the really important point in the Hagtech paper is the resistor - without it, there is no disspition of the ringing energy. You just get ringing at a different frequency...
Shcottky/fast-recovery type diodes shouldn't have caps placed across them - it defeats the fast-recovery benefit because you've added charge at the junction to be dissipated each time the didode goes into recovery.
Shcottky/fast-recovery type diodes shouldn't have caps placed across them - it defeats the fast-recovery benefit because you've added charge at the junction to be dissipated each time the didode goes into recovery.
Martin,
Could you elaborate on the subject of integrated regulators and noise? Is it the LM317 for instance produces HF noise while busy keeping up the voltage?
If so, might it be a solution to place a current source in positive and negative rails feeding the output buffer?.
Regards, Jaap
Could you elaborate on the subject of integrated regulators and noise? Is it the LM317 for instance produces HF noise while busy keeping up the voltage?
If so, might it be a solution to place a current source in positive and negative rails feeding the output buffer?.
Regards, Jaap
Certainly the 317 - like all voltage regulators - actively produces some output noise; it in the datasheets, about 0.003% of Vout IIRC; that means about 150uV on a 5V supply in the audio bandwidth. The noise comes from the internal voltage reference and amplifier. But funnily enough, I don't think it matters much - it is usually swamped by the noise produced by the circuit the reg supplies.
What does seem to happen is that external HF noise can pass through with little attentuation. The main mechanism is obvious - the internal error amp is heavily compensated for stability, so the active bandwidth of 3-pin regs is fairly limited. I'd also speculate that the pass transistor is usually a darlington-type structure, and probably has a fair amount of parasitic capacitance from input to output (I can't measure this directly).
Now - whether the noise that comes thorugh matters in a particular application, and what you can do about it (eg RC or LC filter before the 317) - those are the questions needing answers IMO.
What does seem to happen is that external HF noise can pass through with little attentuation. The main mechanism is obvious - the internal error amp is heavily compensated for stability, so the active bandwidth of 3-pin regs is fairly limited. I'd also speculate that the pass transistor is usually a darlington-type structure, and probably has a fair amount of parasitic capacitance from input to output (I can't measure this directly).
Now - whether the noise that comes thorugh matters in a particular application, and what you can do about it (eg RC or LC filter before the 317) - those are the questions needing answers IMO.
I'm also looking for it... anyone?
Whatever, I've moved, I've recieved my full Ray's upgrade from Fanrell and set up a music room.
Unfortunately the room even if lovely sounds awfull !
I'll try another temporary room this afternoon, any advice to set up the stuff? The planned music room is now my attic...
Whatever, I've moved, I've recieved my full Ray's upgrade from Fanrell and set up a music room.
Unfortunately the room even if lovely sounds awfull !
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I'll try another temporary room this afternoon, any advice to set up the stuff? The planned music room is now my attic...
System set-up / Off-topic
Hi Matthieu,
Diffusion is key for good sound in a typical room. I too have just moved house and the sound of my new room is pretty poor. I have already bought 4 large sheets of 4mm plywood, which I will bend into convex arcs and fix to the walls to act as poly diffusers.
I have also attached 4 wooden CD racks to one wall, which gives some diffusion.
Does it feel nice to be in the room, or does it feel a bit odd and unpleasant? You don't even have to speak (never mind clap your hands) to know if a room will sound good for music, it's obvious. But if it's poor it can often be made good
Speaker placement: get them as wide as they can go and not too close (keep 10cm+) to any walls or you will suffer from a honking midrange. You must sit bang in the middle and not right against the back wall (unless you want a messy bass-heavy sound).
Where to place your electronics is sometimes disputed. Some say (including Russ Andrews) between the speakers is ideal as it keeps the acoustic feedback path short and speaker cables short. The alternative is to use longer speaker cables and find a quiet spot (one with no major room peaks, absolutely not a corner) and place it there, away from the speakers.
How does the system sound bad? We can try to help... altho I'm about to go on holiday for two weeks.. when I return I'll show a pic or two of how I am making my room sound good.
A good room and system/listener placement is really 50%+ of getting good sound! Some people miss this!!
Simon
Malefoda said:
Hi Matthieu,
Diffusion is key for good sound in a typical room. I too have just moved house and the sound of my new room is pretty poor. I have already bought 4 large sheets of 4mm plywood, which I will bend into convex arcs and fix to the walls to act as poly diffusers.
I have also attached 4 wooden CD racks to one wall, which gives some diffusion.
Does it feel nice to be in the room, or does it feel a bit odd and unpleasant? You don't even have to speak (never mind clap your hands) to know if a room will sound good for music, it's obvious. But if it's poor it can often be made good
Speaker placement: get them as wide as they can go and not too close (keep 10cm+) to any walls or you will suffer from a honking midrange. You must sit bang in the middle and not right against the back wall (unless you want a messy bass-heavy sound).
Where to place your electronics is sometimes disputed. Some say (including Russ Andrews) between the speakers is ideal as it keeps the acoustic feedback path short and speaker cables short. The alternative is to use longer speaker cables and find a quiet spot (one with no major room peaks, absolutely not a corner) and place it there, away from the speakers.
How does the system sound bad? We can try to help... altho I'm about to go on holiday for two weeks.. when I return I'll show a pic or two of how I am making my room sound good.
A good room and system/listener placement is really 50%+ of getting good sound! Some people miss this!!
Simon
Re: System set-up / Off-topic
More Simon, I would say even more. A bad room can destroy everyting.
I'm using bass absorbers to get the right amount of bass - (to newcomers in the field of roomtreatment surprisingly enough, the more you absorbs, the more bass (dryer, deeper and tighter) you'll hear)). The "cost" is that you have to have enough juice in you poweramp and your drivers has to deal with more movement.
Else wise I total agree with you. Diffusion either by natural (choice, and placement of interior) or by "building" is a great place to start.
Roomtreatment is overlooked by to many.
SimontY said:
More Simon, I would say even more. A bad room can destroy everyting.
I'm using bass absorbers to get the right amount of bass - (to newcomers in the field of roomtreatment surprisingly enough, the more you absorbs, the more bass (dryer, deeper and tighter) you'll hear)). The "cost" is that you have to have enough juice in you poweramp and your drivers has to deal with more movement.
Else wise I total agree with you. Diffusion either by natural (choice, and placement of interior) or by "building" is a great place to start.
Roomtreatment is overlooked by to many.
You're right, even with a fully modded CD53 I wont catch back my former sound!
As you said, I now feel the room is the n°1 factor. I can have **** or million dollars stuff, it sounds like my laptop computer!
I've moved to the new room, this one even if empty does not " claaAAAAaaapppp " hands
Maybe Holy Björk helped.
This is the target room... for the speakers location, maybe against the high church style wall...
I'm going to make some cheap improvments to the current room, as some old curtains and boxes of dead clothes to help... then start to upgrade the cdp...
As you said, I now feel the room is the n°1 factor. I can have **** or million dollars stuff, it sounds like my laptop computer!
I've moved to the new room, this one even if empty does not " claaAAAAaaapppp " hands
Maybe Holy Björk helped.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
This is the target room... for the speakers location, maybe against the high church style wall...
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I'm going to make some cheap improvments to the current room, as some old curtains and boxes of dead clothes to help... then start to upgrade the cdp...
CD67SE muffled channel output
Hi All,
I put in the split 5v feed mod to my CD67SE at the weekend.
Unfortunately, when I put it all back together I found that 1 channel was working ok (as far as I could tell given the muck from the other) but the other was much quieter and distorting badly.
I know I'll have to start tracing the fault with a multimeter but given that the channel is not completely dead I'm not sure what to look for.
Anyone have any suggestions as to the likely culprit or where best to start looking (I've checked the + and - 12v regs and they're putting out the correct voltages).
Any advice gratefully accepted
Regards
Pete
Hi All,
I put in the split 5v feed mod to my CD67SE at the weekend.
Unfortunately, when I put it all back together I found that 1 channel was working ok (as far as I could tell given the muck from the other) but the other was much quieter and distorting badly.
I know I'll have to start tracing the fault with a multimeter but given that the channel is not completely dead I'm not sure what to look for.
Anyone have any suggestions as to the likely culprit or where best to start looking (I've checked the + and - 12v regs and they're putting out the correct voltages).
Any advice gratefully accepted
Regards
Pete
Re: CD67SE muffled channel output
Hi Pete,
Not knowing what changes you exactly made, it's guesswork.
Look for shorts and bad joints. If nothing shows up undo your mod.
What's clear is that things go wrong after the audiosignal is made analoge because only one of both channels is affected. I would bet on a short around the DAC.
Regards, Jaap
Chivvyp said:Hi All,
I put in the split 5v feed mod to my CD67SE at the weekend.
Unfortunately, when I put it all back together I found that 1 channel was working ok (as far as I could tell given the muck from the other) but the other was much quieter and distorting badly.
I know I'll have to start tracing the fault with a multimeter but given that the channel is not completely dead I'm not sure what to look for.
Anyone have any suggestions as to the likely culprit or where best to start looking (I've checked the + and - 12v regs and they're putting out the correct voltages).
Any advice gratefully accepted
Regards
Pete
Hi Pete,
Not knowing what changes you exactly made, it's guesswork.
Look for shorts and bad joints. If nothing shows up undo your mod.
What's clear is that things go wrong after the audiosignal is made analoge because only one of both channels is affected. I would bet on a short around the DAC.
Regards, Jaap