Hi, everybody, I've just gotten a 1002, has someone changed the output parts to get a better voltage , with a passive preamp I must set it nearly at maximum to get a decent sound level . Nonetheless it is a fantastic machine !
You probably have low-efficiency speakers - that may lead to the volume problems you are describing.
Well, a couple of pages back in this thread, people have described JFET and tube output stages that you may consider. I also have another idea, which has not been discussed before:
If you want to have more output voltage with not too much effort, you can replace the NJM2100 opamp (now operated as a buffer) by a better unit, for example the OPA2134. You have to fumble a bit with the signals and traces (we can discuss this in more detail if you are interested) but it should be possible to use the present opamp position on the board to install a pin compatible unit in non-inverting mode.
In combination with replacing some parts by better equivalents (e.g. the capacitors) and complete removal of some others (e.g. the muting transistors) this should lead to a higher output-voltage level at a better quality than in the stock unit.
Mick
Well, a couple of pages back in this thread, people have described JFET and tube output stages that you may consider. I also have another idea, which has not been discussed before:
If you want to have more output voltage with not too much effort, you can replace the NJM2100 opamp (now operated as a buffer) by a better unit, for example the OPA2134. You have to fumble a bit with the signals and traces (we can discuss this in more detail if you are interested) but it should be possible to use the present opamp position on the board to install a pin compatible unit in non-inverting mode.
In combination with replacing some parts by better equivalents (e.g. the capacitors) and complete removal of some others (e.g. the muting transistors) this should lead to a higher output-voltage level at a better quality than in the stock unit.
Mick
Hi, are you Mick from the Dogbreath web site ? If I 've understood what you wrote , there are two MJM 2100, on the RCA outpout signal path and your idea is to replace one by another AOP ?
Yes, Dogbreath is my site.
In the RCA signal path there is one NJM2100 which is a dual opamp. My idea is to exchange that opamp by an opa2134, which is also dual. Some connections have to be changed to use it as an amplifying stage but that should be possible.
Mick
In the RCA signal path there is one NJM2100 which is a dual opamp. My idea is to exchange that opamp by an opa2134, which is also dual. Some connections have to be changed to use it as an amplifying stage but that should be possible.
Mick
OK, but I'll need your help but don'tworry , I'm not in a hurry . I already have some OAP because I've made some tests on a Philips 723 :
OAP 2277P , 2132PA, 2664AP .
OAP 2277P , 2132PA, 2664AP .
HIgher output level on PSX
Dear gentlemen,
I have already replaced the NJM2100 by an OPA2134 and it works fine. Please be aware that your supply is +5V only, so the maximum output you will get is +/-2,5V peak or 1,76V RMS. Practically it is a bit lower. Regarding the opamp you have to make shure it will allow operating at +5V or +/-2,5V which is very low; anyhow, the OPA2134 will do.
If you desire higher output than above you will have to rise the supply voltage of the opamp. I have plans to realize this idea with a modified PSX powersupply either single +16V or bipolar +/-16V .
The modification on the powersupply is done on the secondary side only. The raw 24V is followed by a linear regulator preferably located close to the opamp. Attached you`ll find a schematic of the bipolar version, for unipolar you have to skip the negative votage generation.
You will have to cut the supply lines of the opamp and connect to the new voltage.
With symmetrical supply you get rid of the output caps, input caps are still required to block the DACs 2,5VDC.
Up to now I only have finished the modification of the power supply, it is working fine.
My final configuration will be opa2134 followed by a push-pull J-FET stage (2SK170, 2SJ74).
Regards,
Jürgen
Dear gentlemen,
I have already replaced the NJM2100 by an OPA2134 and it works fine. Please be aware that your supply is +5V only, so the maximum output you will get is +/-2,5V peak or 1,76V RMS. Practically it is a bit lower. Regarding the opamp you have to make shure it will allow operating at +5V or +/-2,5V which is very low; anyhow, the OPA2134 will do.
If you desire higher output than above you will have to rise the supply voltage of the opamp. I have plans to realize this idea with a modified PSX powersupply either single +16V or bipolar +/-16V .
The modification on the powersupply is done on the secondary side only. The raw 24V is followed by a linear regulator preferably located close to the opamp. Attached you`ll find a schematic of the bipolar version, for unipolar you have to skip the negative votage generation.
You will have to cut the supply lines of the opamp and connect to the new voltage.
With symmetrical supply you get rid of the output caps, input caps are still required to block the DACs 2,5VDC.
Up to now I only have finished the modification of the power supply, it is working fine.
My final configuration will be opa2134 followed by a push-pull J-FET stage (2SK170, 2SJ74).
Regards,
Jürgen
Maybe one can make a power supply only for the OPA ? That's what I have inside my Philips 723 .
Hi Juergen,
nice to see that this idea can be realized. Some questions, however:
- If you use the second half of the Opa2134 as a servo, you need four of them for both channels. You cannot use the footprint of the present opamp then, right? This was one central point of my idea, though.
- If you make an extra supply line for the output stage, then you can use it to give the opa a higher voltage, and hence you dont need the extra jfet stage anymore. Or, argued the other way round, if you build a JFET stage, you dont need the Opa stage....
Cheers,
Mick
nice to see that this idea can be realized. Some questions, however:
- If you use the second half of the Opa2134 as a servo, you need four of them for both channels. You cannot use the footprint of the present opamp then, right? This was one central point of my idea, though.
- If you make an extra supply line for the output stage, then you can use it to give the opa a higher voltage, and hence you dont need the extra jfet stage anymore. Or, argued the other way round, if you build a JFET stage, you dont need the Opa stage....
Cheers,
Mick
Hi Mick,
I agree fully to your comments. Yes you would need 2 dual opamps to do the whole thing on a seperate board.
If you like the minimal versions you could use the footprints of the components.
Personally I prefer the combination of both, the opamp and the JFET buffer stage. To my ears it sounds better than the opamp alone.
To use the buffer alone with an amplification of 1 has already been done in one of my PSXs and I like what I hear. (I even prefer it to the version with OPA2134 alone). This solution is very pure but does not give additional gain, maybe 2 or 3.
So in the end it depends on your personal taste and the equipment you are connecting your PSX to.
Regards,
Jürgen
I agree fully to your comments. Yes you would need 2 dual opamps to do the whole thing on a seperate board.
If you like the minimal versions you could use the footprints of the components.
Personally I prefer the combination of both, the opamp and the JFET buffer stage. To my ears it sounds better than the opamp alone.
To use the buffer alone with an amplification of 1 has already been done in one of my PSXs and I like what I hear. (I even prefer it to the version with OPA2134 alone). This solution is very pure but does not give additional gain, maybe 2 or 3.
So in the end it depends on your personal taste and the equipment you are connecting your PSX to.
Regards,
Jürgen
Gentlemen,
Maybe I should explain more in detail what modifications I have done on my PSX and why I prefer the solution with opamp and JFET buffer combined.
Starting from a first try using the AV connector without the caps installed, my first change was to exchange the opamp from JRC2100 to OPA2134. Without changing any of the caps I noticed only a very small improvement in sound compared to the original, but inferior behaviour compared to using the AV output.
Then I went for the minimal solution and implemented the single ended JFET buffer as posted earlier in this thread. Using the DACs 2.5V DC level I could get rid off of the input caps. I changed the output caps to 10uF polyester. A small hf filter has been added between the DAC and the JFET. Soundwise I like this version more than the above, a bigger improvement than before. Still this version has some drawbacks:
First the supply voltage is 5V only. This is disadvantageous for both the opamp version and the buffer version. You run easily into the limitations of maximum output voltage, depending on the load. So you have little or no headroom.
Increasing the supply voltage helps a lot. Now you can increase the opamps amplification factor from 1 to 2-3 without running into clipping at maximum output from the DAC. Still I would like to add a buffer. A lot of opamps do not like output loads even fine types perform better when not loaded. Adding the JFET buffer to the opamp and closing the loop around both rises new problems: The JFETs parasitic caps may add additional phase shift and worsen the performance.
Therefore I decided to close the loop around the opamp only and add the JFET buffer. With the DC servo I do not need an output cap (bulky). The buffer gives additional decoupling from the cable impedance and the preamp`s input.
This last version of output amp has not yet been implemented in my PSX but is serving as last stage in a RIAA phono amp where I like the sound very much. I think that one advantage of the PSX is its small package, pc board completely shielded and so on. So I wanted to keep the format, no external circuitry.
Regards,
Jürgen
Maybe I should explain more in detail what modifications I have done on my PSX and why I prefer the solution with opamp and JFET buffer combined.
Starting from a first try using the AV connector without the caps installed, my first change was to exchange the opamp from JRC2100 to OPA2134. Without changing any of the caps I noticed only a very small improvement in sound compared to the original, but inferior behaviour compared to using the AV output.
Then I went for the minimal solution and implemented the single ended JFET buffer as posted earlier in this thread. Using the DACs 2.5V DC level I could get rid off of the input caps. I changed the output caps to 10uF polyester. A small hf filter has been added between the DAC and the JFET. Soundwise I like this version more than the above, a bigger improvement than before. Still this version has some drawbacks:
First the supply voltage is 5V only. This is disadvantageous for both the opamp version and the buffer version. You run easily into the limitations of maximum output voltage, depending on the load. So you have little or no headroom.
Increasing the supply voltage helps a lot. Now you can increase the opamps amplification factor from 1 to 2-3 without running into clipping at maximum output from the DAC. Still I would like to add a buffer. A lot of opamps do not like output loads even fine types perform better when not loaded. Adding the JFET buffer to the opamp and closing the loop around both rises new problems: The JFETs parasitic caps may add additional phase shift and worsen the performance.
Therefore I decided to close the loop around the opamp only and add the JFET buffer. With the DC servo I do not need an output cap (bulky). The buffer gives additional decoupling from the cable impedance and the preamp`s input.
This last version of output amp has not yet been implemented in my PSX but is serving as last stage in a RIAA phono amp where I like the sound very much. I think that one advantage of the PSX is its small package, pc board completely shielded and so on. So I wanted to keep the format, no external circuitry.
Regards,
Jürgen
Battery as power supply
Hi everybody,
i was reading first twenty pages and I was wondering how come nobody have said anything about using battery instead wall-wart as power supply for PS1. Would that be good idea or I have missing something.
Thanks and congratulations on great discovery in High-End Audio(PS1 of course),
BenJ
Hi everybody,
i was reading first twenty pages and I was wondering how come nobody have said anything about using battery instead wall-wart as power supply for PS1. Would that be good idea or I have missing something.
Thanks and congratulations on great discovery in High-End Audio(PS1 of course),
BenJ
Using batteries will be rather elaborate. You need two voltages which are no standard battery values (3.6 and 7.6 V) so regulators are required also with batteries, and the circuit constantly draws 500mA on each voltage rail, i.e. you need high capacities.
Mick
Mick
Batteries actually "sizzle" a bit. thay are not as clean as people think.
I might use them for an amplifier, where high current for short durations is required, but they may not be a good idea for constant current wioth low levels.
So some earching around the forum and the net before you decide on batteries.
I might use them for an amplifier, where high current for short durations is required, but they may not be a good idea for constant current wioth low levels.
So some earching around the forum and the net before you decide on batteries.
PS1 Console Testing
Is there anyway to test the console (initiate a "play" sequence) on the PS1 w/o the controller? I see lonely consoles in thrift stores, would like to test them before buying.
Is there anyway to test the console (initiate a "play" sequence) on the PS1 w/o the controller? I see lonely consoles in thrift stores, would like to test them before buying.
Re: PS1 Console Testing
Keep a controller in your pocket? Buy a cheap remote off ebay, you will no doubt use it once you have found a PS1 to your liking.
How will you listen to it anyway?
If you just want to check it's working then it should spin up with a disk in from power on.
DreadPirate said:
Keep a controller in your pocket? Buy a cheap remote off ebay, you will no doubt use it once you have found a PS1 to your liking.
How will you listen to it anyway?
If you just want to check it's working then it should spin up with a disk in from power on.
Re: Re: PS1 Console Testing
Thanks for tips. Is the 1001 that is the "best", the only one with RCA jacks? If it has RCA jacks, should I just grab?
What cheap remote is best? From Mike's page, looks like there may be mods necessary to get PS2 remote unit to work with PS1?
I intend on hooking up to main system just like a standard CD player (rca jacks).
Thanks for tips. Is the 1001 that is the "best", the only one with RCA jacks? If it has RCA jacks, should I just grab?
What cheap remote is best? From Mike's page, looks like there may be mods necessary to get PS2 remote unit to work with PS1?
I intend on hooking up to main system just like a standard CD player (rca jacks).
Lostcause said:
No mods are required for remote control. Just plug the receiver into the port.
More work is only necessary if you want to include the receiver into the case.
Mick
More work is only necessary if you want to include the receiver into the case.
Mick
Does the SCPH-5501 have built in RCA jacks? If not, do I just come off the DAC and do the old "Swenson Mod"? From what I've read these are good sounding too and probably more reliable than the 1001. Any comments on that?
Hi everyone soundlovers,
I have tried a bridge of 4 MBR60100CT Schottky diodes instead of
MUR860 or MSR860 on the power supply of Mister Mick Fuerbacher.
It's amazing.... total other sound.
I don't know when using Schottky's it is necessary to recalculate the capacitors for the psu or there must other things change.
However it sounds better, minus harsch ! Try it !....
😉
I have tried a bridge of 4 MBR60100CT Schottky diodes instead of
MUR860 or MSR860 on the power supply of Mister Mick Fuerbacher.
It's amazing.... total other sound.
I don't know when using Schottky's it is necessary to recalculate the capacitors for the psu or there must other things change.
However it sounds better, minus harsch ! Try it !....
😉