When I replace C301 with 1 uf, and remove R305, should I remove C303 ( on the left scheme) and put a wire instead of it. On the right scheme I see only 1 cap after the pot. (C303, marked with yellow)
You need to bypass (short it out) one of the caps. This is how mine looked after the mods. I bridged the new caps across the the holes.
Also note: these pics were taken before adding the additional diode in series with D301/303, D302/304 - from memory, I just lifted one leg, and soldered the additional diode in series - it was a simple mod to do (as are all the other mods).
After looking at the images I took - I remembered I modified the headphone board too. I fitted a stronger socket (mine was plastic and broken).
I also fitted an upgraded OPAMP RC4560D.
On the HP board, I removed the muting transistors Q401/402, the resistors that provide the switching current for these (not really necessary to remove, but done for completeness). R401/402 were changed for lower impedance (100R from memory), R403/404 were increased to ~75k, and R407/408 were reduced to ~2k7 to reduce overall gain. I didn't change mine, but C403/404 (100uF) could be usefully increased (470uF would be good) if driving lowish impedance headphones.
These are the parts I changed on the HP board - the red ones can be removed (they are for muting).
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Thanks Tony for shearing so detailed and useful information ! Do you think it is a good idea to change the power cord with a good audio cord. And put a power socket IEC C14 with a filter as well.. Something like this :
You have to be careful with these sockets, because they depend on a 3 core mains feed, which means that your preamp will become referenced to mains ground.
The 1000 is a double insulated device, and as such only requires a 2 core cable with no earth.
You could possibly use a different type of filter - one that doesn't require a ground reference. DON'T try and use the one above without a ground - as the ground will rise to mains potential due to the two caps (Cy) connecting live and neutral to ground.
Ok, thanks ! Probably I will use 2 core audio power cable with a socket without a filter and no ground as well.
I would like to tell me your opinion : Here is the story of my NAD 1000 . An year ago I bought Pro-ject Pre Box S2 Digital which is a DAC with preamp and power amplifier Atoll AM 100 Signature. The speakers are Klipsch RP 600M. I connected everything and I was in shock : the sound was not good at all, without any live. Even Pro-ject Pre Box S2 Digital is a pre amplifier I decided to try to put an other preamp before the Atoll AM 100. I found on the second hand market NAD 1000 in very good condition and on a good price and a bought it. When a connected it to the system everything just expanded a lot , the sound became wider, very live etc. I was so inspired so I recaped the NAD1000, bought better interconnects and speaker cables, bought a streamer IFi Streamer with a silent power supply. The sound now is amazing for my taste. Can you please tell me your opinion why additional device ( in this case NAD 1000) can make so big improvement? In general on theory every addition should make the sound worse, In my case I put 2 preamps one after an other....?
The Pre Box S2 is probably not good enough to pair with the Atoll. To me, the Pre Box looks more like a DAC with a volume control.
And you say "In general on theory every addition should make the sound worse" - this is not necessarily true - making a truly transparent pre / line amp is very easy to do.
If you insert any line amplification into the signal path and it degrades the sound, then it is either poorly designed or faulty in my opinion.
But in your case, I suspect the Pre Box is simply outclassed by the Atoll - and the Atoll needs a better preamp (which you have in the NAD).
And you say "In general on theory every addition should make the sound worse" - this is not necessarily true - making a truly transparent pre / line amp is very easy to do.
If you insert any line amplification into the signal path and it degrades the sound, then it is either poorly designed or faulty in my opinion.
But in your case, I suspect the Pre Box is simply outclassed by the Atoll - and the Atoll needs a better preamp (which you have in the NAD).
There is an other thing: For me almost always the sound is better when I put the treble on the NAD to max ( +7 dB)
The bass is always on 0. Do you thing there is something wrong in the chain ?
The bass is always on 0. Do you thing there is something wrong in the chain ?
You have a serious* issue in your setup.
I can not believe the Pro-ject Pre Box S2 Digital to be so bad**. Secondly the S2 is still in the chain but without penalty so it is not the direct cause. Apparently the S2 and Atoll don't like each other much. It would pay off to investigate what is going on. Is it the low input impedance of the Atoll for instance? How about grounding/PE/RF issues? Have you tried the simple trick of plugging in Schuko power plugs 180 degrees turned (if you are in EU)?
*Another cause could be hearing problems. I have dealt with that in my circle and some wanted outrageous treble levels that were ear bleeding to those that had OK hearing. Many people with severe hearing issues simply refused to acknowledge this and blamed the others for not coping with very high volume levels and such. This all caused misunderstanding, irritation and sometimes a high count of defective tweeters. If this is the cause you will be on a deviating path as then it becomes not HiFi but adaptation to an unfortunate shortcoming. The setting of treble to +7 dB is not normal and it would explain why you don't like the direct connection of S2 to the Atoll. This can easily be verified to just use another inserted device with tone control set to highest setting. If you like that as well you have an answer.
** Did you test with the various filters of the S2? What about the flat setting?
I can not believe the Pro-ject Pre Box S2 Digital to be so bad**. Secondly the S2 is still in the chain but without penalty so it is not the direct cause. Apparently the S2 and Atoll don't like each other much. It would pay off to investigate what is going on. Is it the low input impedance of the Atoll for instance? How about grounding/PE/RF issues? Have you tried the simple trick of plugging in Schuko power plugs 180 degrees turned (if you are in EU)?
*Another cause could be hearing problems. I have dealt with that in my circle and some wanted outrageous treble levels that were ear bleeding to those that had OK hearing. Many people with severe hearing issues simply refused to acknowledge this and blamed the others for not coping with very high volume levels and such. This all caused misunderstanding, irritation and sometimes a high count of defective tweeters. If this is the cause you will be on a deviating path as then it becomes not HiFi but adaptation to an unfortunate shortcoming. The setting of treble to +7 dB is not normal and it would explain why you don't like the direct connection of S2 to the Atoll. This can easily be verified to just use another inserted device with tone control set to highest setting. If you like that as well you have an answer.
** Did you test with the various filters of the S2? What about the flat setting?
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I agree with jean-paul - having the treble turned right up suggests some issue somewhere, especially with those Klipsch speakers which are known to be bright sounding!
Are the biwire links in place on the back of the speakers?
Are the biwire links in place on the back of the speakers?
I have tried several times without the NAD , only the Pro-jet and the Atoll but the sound is not good for me. When I use a CD player as a source I also prefer the treble to be +7 db on the NAD. If I put the treble on 0 the sound become some kind of dark, I do not enjoy the music much. Also I mentioned that jazz, classical music ( in general slow music) sounds much much better than rock , heavy metal, etc. May be it is a matter of the quality of the record.
Unfortunately I have some hearing problems with the left ear but not something significantly.
Unfortunately I have some hearing problems with the left ear but not something significantly.
Ah you already excluded that the S2 is the cause. Then your remark "The Pre Box S2 is probably not good enough to pair with the Atoll." is simply not right.
1. If the S2 was not good enough it would also be not good enough when coupled with the NAD. With another source the issue is the same so you are having treble loss either elsewhere in the chain or in the hearing.
2. The insertion of a superfluous device apparently works out OK because it can have extreme treble. Any other device with extreme treble levels will then be to your likings. If the S2 would have a +7dB treble setting you would like it.
3. If these findings in 1. and 2. are right a simple small circuit upping treble 6 or 7 dB would be sufficient. You wouldn't need the large NAD and added noise/distortion at all.
4. Have you excluded the loudspeakers? If the tweeters are damaged/kaputt/missing biwire links that would be sad but solvable.
5. What about trying out another amplifier? Just to exclude.
My well meant advice when all technical defects have been excluded and all is working correctly: have your ears measured and mention the treble loss. Ask for graphs/numbers and let them explain to you.
BTW you don't answer questions that are asked to help you solve YOUR issue. It costs other peoples time and not replying is simply not cooperative.
1. If the S2 was not good enough it would also be not good enough when coupled with the NAD. With another source the issue is the same so you are having treble loss either elsewhere in the chain or in the hearing.
2. The insertion of a superfluous device apparently works out OK because it can have extreme treble. Any other device with extreme treble levels will then be to your likings. If the S2 would have a +7dB treble setting you would like it.
3. If these findings in 1. and 2. are right a simple small circuit upping treble 6 or 7 dB would be sufficient. You wouldn't need the large NAD and added noise/distortion at all.
4. Have you excluded the loudspeakers? If the tweeters are damaged/kaputt/missing biwire links that would be sad but solvable.
5. What about trying out another amplifier? Just to exclude.
My well meant advice when all technical defects have been excluded and all is working correctly: have your ears measured and mention the treble loss. Ask for graphs/numbers and let them explain to you.
BTW you don't answer questions that are asked to help you solve YOUR issue. It costs other peoples time and not replying is simply not cooperative.
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Sorry Jean -Paul but for some reason your previous post did not appear in my browser on time. I did not see it that is why I did not answer.
Bellow are the answers:
1.Have you tried the simple trick of plugging in Schuko power plugs 180 degrees turned? - Yes I tried , no difference.
2.Did you test with the various filters of the S2? What about the flat setting?- Yes , I did, the differences are very small, almost negligible.
3.Are the biwire links in place on the back of the speakers?- Yes , they are very well tight.
4. Have you excluded the loudspeakers? If the tweeters are damaged/kaputt/missing biwire links that would be sad but solvable. - The speakers are OK. I bought them brand new.
5. What about another amplifier? Just to exclude. - I have not tried an other amplifier, but before the Atoll I had Yamaha R -N 303 D where I also liked more the treble to be up . Now with the Atoll , Pro-ject and NAD the sound is much better and detailed if I compare to the Yamaha.
Bellow are the answers:
1.Have you tried the simple trick of plugging in Schuko power plugs 180 degrees turned? - Yes I tried , no difference.
2.Did you test with the various filters of the S2? What about the flat setting?- Yes , I did, the differences are very small, almost negligible.
3.Are the biwire links in place on the back of the speakers?- Yes , they are very well tight.
4. Have you excluded the loudspeakers? If the tweeters are damaged/kaputt/missing biwire links that would be sad but solvable. - The speakers are OK. I bought them brand new.
5. What about another amplifier? Just to exclude. - I have not tried an other amplifier, but before the Atoll I had Yamaha R -N 303 D where I also liked more the treble to be up . Now with the Atoll , Pro-ject and NAD the sound is much better and detailed if I compare to the Yamaha.
4. Should still be checked as new things can be incomplete etc. Always check and double check. Example: how many times I have been shown setups that were excellent according the owners but that I just did not think it sounded OK and discovered 1 loudspeaker had + and - in reverse so out of phase ….
Otherwise it is the hearing. Sorry. The difficulty in this is the separation from the average norm. I know a very nice guy with tinnitus that never likes normal loudspeakers as he experiences those as metallic sounding. Such deviations result in either deviating setups only suited to the owner. This is hard to accept and therefor often blamed to the world.
You could try out a simple treble upping circuit instead of the NAD en when you like it you will know it is not the NAD being magical.
Otherwise it is the hearing. Sorry. The difficulty in this is the separation from the average norm. I know a very nice guy with tinnitus that never likes normal loudspeakers as he experiences those as metallic sounding. Such deviations result in either deviating setups only suited to the owner. This is hard to accept and therefor often blamed to the world.
You could try out a simple treble upping circuit instead of the NAD en when you like it you will know it is not the NAD being magical.
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In my profession hearing loss is standard (imagine being an audiophile trying to keep his ears 100%). Some are in their thirties and already hard hearing. One of my older colleagues was becoming deaf and he was very worried.
He visited an old special doctor who operated his ears (high risk and uncommon practice). His hearing was quite normal again after this. Sometimes you are lucky and sometimes you aren’t.
I had an incident with a very high power switch and BAM!!! instant beeping and damage. Went straight to a doctor and got the in German speaking countries standard Spritze. Completely went away, pffffff. Relief!
He visited an old special doctor who operated his ears (high risk and uncommon practice). His hearing was quite normal again after this. Sometimes you are lucky and sometimes you aren’t.
I had an incident with a very high power switch and BAM!!! instant beeping and damage. Went straight to a doctor and got the in German speaking countries standard Spritze. Completely went away, pffffff. Relief!
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I am glad to hear everything went well for you after the accident. With the ages probably for every one of us the hearing, especially in the high frequencies goes down.....
May be it is a good idea to go somewhere and listen somebody else good Hi -Fi system without tone correction ( +7 db treble) and see if I will like it. Or to go to a Hi-Fi show and see if I will find something that I like without busted high frequencies.
Can somebody suggest me a good circuit for upping treble around 7 dB . It will be between the preamp and the power amp ? . I wold like to try one of the tips Jean Paul gave me....
Do you have a laptop and a microphone?
If so, download and install Arta (ignore the instruction to get a licence key - you can install and run it without a licence) - and then run some checks on your system.
IMPORTANT! Start off at a low volume, and set all tone controls / other adjustments to 'flat'.
Playback some white noise (Arta can generate this for you) and look at the spectrum (capture it and post it here) and we can tell you if anything is obviously wrong.
You can also try a pink noise capture.
Obviously, results will depend on the quality of your microphone, however if there is something obviously wrong, it should be visible anyway.
If so, download and install Arta (ignore the instruction to get a licence key - you can install and run it without a licence) - and then run some checks on your system.
IMPORTANT! Start off at a low volume, and set all tone controls / other adjustments to 'flat'.
Playback some white noise (Arta can generate this for you) and look at the spectrum (capture it and post it here) and we can tell you if anything is obviously wrong.
You can also try a pink noise capture.
Obviously, results will depend on the quality of your microphone, however if there is something obviously wrong, it should be visible anyway.