Hi,
This preamp has been an old faithful but I've noticed an issue which I don't think is a new one.
Most noticeably, when I listen to piano Music, there are at times peaks that sound like mild clipping. I've had different combos of amps, cd players, cables and speakers and it always comes back to this preamp as being the culprit.
Sounds fine with the matching tuner always. Does this point to a cap issue?
Thanks!
This preamp has been an old faithful but I've noticed an issue which I don't think is a new one.
Most noticeably, when I listen to piano Music, there are at times peaks that sound like mild clipping. I've had different combos of amps, cd players, cables and speakers and it always comes back to this preamp as being the culprit.
Sounds fine with the matching tuner always. Does this point to a cap issue?
Thanks!
Nikko is very nice equipment ... nothing that is done in 5 minutes ...designers have been seriously working to create them
in such age you have to replace most electrolytics inside ....easy task to do inexpensive but time consuming ( for an amature if you are )
given the chance many of the capacitors inside can be replaced for a lot better ones and this is expected to alter the sound of the preamp for the best ...
Changes need to be verified by instruments and you need to be prepared to listen to an "other" preamp after the recap or the upgrade
kind regards sakis
in such age you have to replace most electrolytics inside ....easy task to do inexpensive but time consuming ( for an amature if you are )
given the chance many of the capacitors inside can be replaced for a lot better ones and this is expected to alter the sound of the preamp for the best ...
Changes need to be verified by instruments and you need to be prepared to listen to an "other" preamp after the recap or the upgrade
kind regards sakis
I'm grave digging a bit on this thread, but I didn't stop using this pre. As a matter of fact, I've been using a TT, tape deck, tuner and cd player with it. Now I'm not sure the problem has completely gone away but it's been some time since I've heard it. Maybe using it continuously like I have been lately has caused some reforming? It did sit for a few years and was hooked up on some occasions.
Could be dirty controls that were causing the issue and now with all the use they are freed up a bit.
Thanks
Could be dirty controls that were causing the issue and now with all the use they are freed up a bit.
Thanks
could be also weather conditions .... lower or higher temp might effect soldering and/or performance
Upgrades in users like you ( people that know and use the equipment daily and know them inside out ) usually are very effective cause the user can listen to the difference instantly .
None of he NIkko i repaired in the past had working capacitors inside all of them where just about ok with more than 15% tolerance...
these are simple facts ... keep them in mind
Kind regards
sakis
Upgrades in users like you ( people that know and use the equipment daily and know them inside out ) usually are very effective cause the user can listen to the difference instantly .
None of he NIkko i repaired in the past had working capacitors inside all of them where just about ok with more than 15% tolerance...
these are simple facts ... keep them in mind
Kind regards
sakis
Thanks guys.
The pre is driving my tube amp, and come to think of it, the pre is also still hooked up to a big solid state amp that is not being used now. I imagine there must be some resistive load, albeit small, on the preamps output.
No doubt the problem didn't show up from other sources in the past for the reason mentioned Sam.
The pre is driving my tube amp, and come to think of it, the pre is also still hooked up to a big solid state amp that is not being used now. I imagine there must be some resistive load, albeit small, on the preamps output.
No doubt the problem didn't show up from other sources in the past for the reason mentioned Sam.
Pure Brew, You did say your problem is with a CD player, but not with a tuner, right?
I'm not aware of the age of the NIKKO but some equipment that was older than 1983 (intro, of CDs) would clip or rather, just distort more when 2V CD signals were fed where 250 mV signals were expected. A lot of good equipment was sold off or just sidelined when this happened here. Tandy/Radio Shack, I think, also sold a lot of little in-line attenuators
This may not be the actual situation and it may have worked fine some time ago, so failing caps and their related power supplies are still a strong likelihood, as Sakis suggests. Obviously this is a signal level issue and is before the volume control, if it persists at all settings.
I would attenuate the CD input, borrow a player with a level control on the output etc. as the options are available to you and test this first. You may find, even listening to the relative levels of tuner and CD, that this is the matter. The fix then is easy but re-capping, if you like your NIKKO, is still a must in the line/preamp section at least.
One last simple suggestion - play The CD through the tape in/monitor sockets - some pre-amps have less sensitivity there.
I'm not aware of the age of the NIKKO but some equipment that was older than 1983 (intro, of CDs) would clip or rather, just distort more when 2V CD signals were fed where 250 mV signals were expected. A lot of good equipment was sold off or just sidelined when this happened here. Tandy/Radio Shack, I think, also sold a lot of little in-line attenuators
This may not be the actual situation and it may have worked fine some time ago, so failing caps and their related power supplies are still a strong likelihood, as Sakis suggests. Obviously this is a signal level issue and is before the volume control, if it persists at all settings.
I would attenuate the CD input, borrow a player with a level control on the output etc. as the options are available to you and test this first. You may find, even listening to the relative levels of tuner and CD, that this is the matter. The fix then is easy but re-capping, if you like your NIKKO, is still a must in the line/preamp section at least.
One last simple suggestion - play The CD through the tape in/monitor sockets - some pre-amps have less sensitivity there.
I know this is an old thread, but I do have a question about this preamp and I see no point of starting a new one.
I got this preamp of ebay, cheap, I believe I paid $9 +sh for it, and offcourse I tested it and found an issue.
Well, it sounds pretty good on every input, and its phono mm itput is fine, actually I am very pleased with its sound, certainly nicely done phono preamp, just the mc input is very quiet, something is wrong there.
I am using low output benz micro on one turntable, and if I use mm input with step up transformer, it sounds great. When I want to run the cart without step up, just use mc input, its mute. There is some sound comming thru, but its too quiet. So obviously there is somethig wrong with pre-pre. I tested on other turntable with ATOC9, the same outcome. I could live with step up trafo, I have quite a few of those, but I am intrigued as to what could be wrong.
When I looked inside, obviously first think I did, to clean the pots and switches, it lookes like noone ever opened the unit, it looks all original. I assume all the caps are original.
I replaced input and ouput caps in the pre-pre sections, but no inprovement. I checked all the voltages on transistors, all reads fine. I have not taken any transistor out, as I believe they should be fine, if all the voltages are as they should.
Anybody has any idea what should I do? Thanks a lot.
I got this preamp of ebay, cheap, I believe I paid $9 +sh for it, and offcourse I tested it and found an issue.
Well, it sounds pretty good on every input, and its phono mm itput is fine, actually I am very pleased with its sound, certainly nicely done phono preamp, just the mc input is very quiet, something is wrong there.
I am using low output benz micro on one turntable, and if I use mm input with step up transformer, it sounds great. When I want to run the cart without step up, just use mc input, its mute. There is some sound comming thru, but its too quiet. So obviously there is somethig wrong with pre-pre. I tested on other turntable with ATOC9, the same outcome. I could live with step up trafo, I have quite a few of those, but I am intrigued as to what could be wrong.
When I looked inside, obviously first think I did, to clean the pots and switches, it lookes like noone ever opened the unit, it looks all original. I assume all the caps are original.
I replaced input and ouput caps in the pre-pre sections, but no inprovement. I checked all the voltages on transistors, all reads fine. I have not taken any transistor out, as I believe they should be fine, if all the voltages are as they should.
Anybody has any idea what should I do? Thanks a lot.
Attachments
Hi sakis, thanks for fast response. I checked +/- 12 volts suply, it works fine, if it would not, servo in next stage would not work. So I measure correct +/- 12 volts comming to pre-pre, and most of the voltages indicated in the schematics are close to the spot.
I replaced already two input capacitors in each half, and two output caps. Should I go ahead and replace all of the caps in pre-pre section? I need something more specific to go after.
I replaced already two input capacitors in each half, and two output caps. Should I go ahead and replace all of the caps in pre-pre section? I need something more specific to go after.
Are both channels equally affected... I'm guessing so.
Strange problem. Obviously check supplies as sakis mentions. Beyond that, and I think I'd be looking closely for some quirk in its operation first off. Switch positions/jumpers etc.
Might help to see a bit more of the circuit and the switch operation. As shown it should have masses of gain. Worth checking physical continuity across the switch and confirming that the 1K and 10 ohm really are in contact.
That servo looks scary with a 741 and large (diy
) bipolar caps.
Strange problem. Obviously check supplies as sakis mentions. Beyond that, and I think I'd be looking closely for some quirk in its operation first off. Switch positions/jumpers etc.
Might help to see a bit more of the circuit and the switch operation. As shown it should have masses of gain. Worth checking physical continuity across the switch and confirming that the 1K and 10 ohm really are in contact.
That servo looks scary with a 741 and large (diy
) bipolar caps.
Hi gents, here is an update. There are good news and there are bad news. The good news is that pre-pre section is working, the bad news is that phono selector is totaly busted. Well, from the front it behaves fine, you can select four positions, it has nice feel to it, it clicks. However, from that mechanism on the front pannel, which includes two plastic wheels with teeth, there is long flat cable which has flat metal advancing in and out, you know what I mean, an that part is not moving. So its only in one position, no matter what is selected on the front pannel. So the mystery is solved.
Unfortunately, there is no way I can fix that, since even the actual selector on the board is busted, it has some broken plastic parts inside. There is no way I can replace it, first I have no parts to replace it with, second it has dozens of pins soldered on the pcb. All I can do this time is to fix it in one position by wires.
In any case, thanks for the help.
Unfortunately, there is no way I can fix that, since even the actual selector on the board is busted, it has some broken plastic parts inside. There is no way I can replace it, first I have no parts to replace it with, second it has dozens of pins soldered on the pcb. All I can do this time is to fix it in one position by wires.
In any case, thanks for the help.
yes, yes, those are the switches...boywonder, thanks for the offer, but please do not do it, thats way too much work and I am affraid it would not lead to success
those switches in nikko are most likely configured differently, it would be hard to match the contacts, the preamp phono switch has four positions in three sections (the schematics I provided is only part of it...; mc, phono 1 47k, phono 1 100k, phono 2...that is 12 pins per side, 24 pins on the pcb to unsolder, I do not want to do that...
I am going to make simple selector mc / mm...it will take just one switch on the back
this preamp is never be for anybody else but for me, so it can be ugly and moded, so the switch on the back is no problem, swith on the front will be non-functional
I plan to use this for experimentations, since I do have better preamps...
those switches in nikko are most likely configured differently, it would be hard to match the contacts, the preamp phono switch has four positions in three sections (the schematics I provided is only part of it...; mc, phono 1 47k, phono 1 100k, phono 2...that is 12 pins per side, 24 pins on the pcb to unsolder, I do not want to do that...
I am going to make simple selector mc / mm...it will take just one switch on the back
this preamp is never be for anybody else but for me, so it can be ugly and moded, so the switch on the back is no problem, swith on the front will be non-functional
I plan to use this for experimentations, since I do have better preamps...
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.