Nothing exotic, but the commonly used Elna (and Panasonic) is usually good. I'm talking about the main supply cap here. Few years ago, the only good quality cap around was a black Nippon Chemicon. I think some fakers forgot and missed this model. Oh, and I didn't measure but listened, so it is natural if I prefer the better sounding one, even if it is old
D)I meant physically "axial". They usually are better sounding capacitors. And BTW, I'm not sure if durability (of the caps for example) will improve the profit margin of the manufacturer.
That was my point: regarding sound quality.
Yes, I understand the situation. It is good if you can replace everything and the customer pay for that. But if you own such a low quality amps such as the ones you have in your repair shop, will you replace all the caps? Me, absolutely not (and I'm talking from experience).
Oh yes, no doubt about that cap in the feedback chain. They are never too good to keep.
What I have learned here is that with old caps in the main supply, I may experience a "boom" once in a lifetime. But it seems that it would not happen, because when it still sound good, it means it is not dried, and I don't know why should there be a "boom". I have never experienced or seen things like that happen. My god, my aikido uses a very very old cap in the 300V power supply (just because it sounded good). I will have to replace that
Thanks
SERVICE YAMAHA AX 700
I WILL .. spent a few moment s not to describe any goods of the Ax 700 but mostly a situation and a story of a damage ...
Symptom was that the amp was breaking up but only at very low power ...one may think that its a pot issue ... i did the same thing and actually i was wrong big time .... You see log pots often do things like that but in very low power .
the problem was the output relay
funny thing is that it had been to YAMAHA service center before and they didn't replace the relay they just cleaned the contacts ...
funny thing is that the relay was defective any way regardless the clean or not issue since contacts was misplaced and was impossible to meet as can be seen from the pics
Most nice of all though is that the relay features some duct tape on it to support two small ferrite breads next to the relay coil ...I cannot understand what happens here ? while measuring the amp the Yamaha people found out that the coil produced some high pitch noise and wanted to suppress it with the ferrite ?
if so that is a remarkable detail and show how much caution was given to their products at the time ...
enjoy some relay pics
I WILL .. spent a few moment s not to describe any goods of the Ax 700 but mostly a situation and a story of a damage ...
Symptom was that the amp was breaking up but only at very low power ...one may think that its a pot issue ... i did the same thing and actually i was wrong big time .... You see log pots often do things like that but in very low power .
the problem was the output relay
funny thing is that it had been to YAMAHA service center before and they didn't replace the relay they just cleaned the contacts ...
funny thing is that the relay was defective any way regardless the clean or not issue since contacts was misplaced and was impossible to meet as can be seen from the pics
Most nice of all though is that the relay features some duct tape on it to support two small ferrite breads next to the relay coil ...I cannot understand what happens here ? while measuring the amp the Yamaha people found out that the coil produced some high pitch noise and wanted to suppress it with the ferrite ?
if so that is a remarkable detail and show how much caution was given to their products at the time ...
enjoy some relay pics
Great thread, Sakis.
The Luxman LV-105U looks very interesting - the first hybrid tube/solid-state amplifier from a mass manufacturer that I've ever seen. Does anybody know of others like it?
I would be much obliged if you could post the schematic (or a link to it).
EDIT: found the service manual at http://wegavision.pytalhost.com/luxmanLv-105us/
The Luxman LV-105U looks very interesting - the first hybrid tube/solid-state amplifier from a mass manufacturer that I've ever seen. Does anybody know of others like it?
I would be much obliged if you could post the schematic (or a link to it).
EDIT: found the service manual at http://wegavision.pytalhost.com/luxmanLv-105us/
Last edited:
It's interesting alright. I've seen a piece of mild steel curved to fit around the coil too, as a modification to Chinese clones of that pattern in your pics.
I didn't think about it at the time, but it does change the closing force and frequency of chatter if there is enough iron. I never found out where the buzz of relay coils originated if the supply is clean DC. Ferro-resonance somewhere but with the PSU?
I imagine ferrite was very common in Telecom operations and technicians usually had cartons of the stuff - It's where I got even RF slugs, bobbins, potcores, some toroids and even Transformer mouldings in those days anyway
SERVICE NAD 3150
i dont like nad amps of that time and that series
Personally i like amps that are absolute and truth ....obviously machines like that include the perfect playing of nice productions but also include the danger of playing a bad production that actually will sound even worst as a final result.
It seems to me that this time NAD's tend to round the edges or leave you with impression that the sound you listen might be sweet but is somehow processed by something ...is not natural ...
It seems to me that sound is like someone introduced one EQ to the system and then someone else introduced another EQ to cancel the tonal diference from the previous EQ .
Chaotic construction a zillion voltages inside plenty of local stabilization marginal trafos and huge output transistors..
---All electrolytic needed to be replaced
---Plenty of soldering to be done
---some rearrangement of capacitors
--- sealed trimmers
--- tune it ...scope it and let go ...
i am not thrilled....
gut fotos and schematic available
i dont like nad amps of that time and that series
Personally i like amps that are absolute and truth ....obviously machines like that include the perfect playing of nice productions but also include the danger of playing a bad production that actually will sound even worst as a final result.
It seems to me that this time NAD's tend to round the edges or leave you with impression that the sound you listen might be sweet but is somehow processed by something ...is not natural ...
It seems to me that sound is like someone introduced one EQ to the system and then someone else introduced another EQ to cancel the tonal diference from the previous EQ .
Chaotic construction a zillion voltages inside plenty of local stabilization marginal trafos and huge output transistors..
---All electrolytic needed to be replaced
---Plenty of soldering to be done
---some rearrangement of capacitors
--- sealed trimmers
--- tune it ...scope it and let go ...
i am not thrilled....
gut fotos and schematic available
Last edited:
SERVICE GAS SON OF AMPZILLA
GAS ...stands for :great American sound
I have in mind that these people actually mean what they say .... very nice amp after almost 40 years a pioneer design quick , powerful , rich, clean tolerant on a variety of loads...massive construction and simple but very effective metalwork ...
I think it sounds much better than a 555 but the construction is by far lighter and less robust next to an ADCOM ....
After 40 years only things to be replaced was:
---all electrolytic capacitors
---one diode
---4 bulbs
---a couple of RCA plugs in the input
and that's about it ...Now watching a very nice 40KHZ square wave on my scope actually ... thrilled me
schematic is available ...and as about noises and input transistors that some claimed to have problems with i 've noticed absolutely nothing but that is after i fixed all power supply sections and cleaned all contacts and corrosion very carefully ...
inner fotos
GAS ...stands for :great American sound
I have in mind that these people actually mean what they say .... very nice amp after almost 40 years a pioneer design quick , powerful , rich, clean tolerant on a variety of loads...massive construction and simple but very effective metalwork ...
I think it sounds much better than a 555 but the construction is by far lighter and less robust next to an ADCOM ....
After 40 years only things to be replaced was:
---all electrolytic capacitors
---one diode
---4 bulbs
---a couple of RCA plugs in the input
and that's about it ...Now watching a very nice 40KHZ square wave on my scope actually ... thrilled me
schematic is available ...and as about noises and input transistors that some claimed to have problems with i 've noticed absolutely nothing but that is after i fixed all power supply sections and cleaned all contacts and corrosion very carefully ...
inner fotos
service pioneed sx 680
a true vintage machine from Pioneer based on STK 0039 IC with the only benefit that external parts such was LTP , VAS and VBE are discrete and this can make some difference at least next to ""all included"" STK
classic vintage sound full of colors and sonics very etchy loudness extra sensitive tuner that is actually very accurate ...
Had to replace most electrolytics , replace one STK IC , do a good cleaning tune the radio a bit and that's about it
gut foto and schematics available
enjoy
a true vintage machine from Pioneer based on STK 0039 IC with the only benefit that external parts such was LTP , VAS and VBE are discrete and this can make some difference at least next to ""all included"" STK
classic vintage sound full of colors and sonics very etchy loudness extra sensitive tuner that is actually very accurate ...
Had to replace most electrolytics , replace one STK IC , do a good cleaning tune the radio a bit and that's about it
gut foto and schematics available
enjoy
based on this http://www.diyaudio.com/forums/soli...ur-solid-state-pics-here-219.html#post2853259 JAcco is ""calling" me a dentist ...
well years ago i liked very much the tools he used and actually visited a shop with all the dentist hardware.... beyond tweezers and "fingers" i realized that the bits used to drill the tooth make a wonderful pcb drill ...it can drill high speed drills in the pcb and will not leave flash around the drill ...( ALSO DREMEL COMPATIBLE )
also i learned that now days ultrasonic except cleaning tooth and soldering leftovers might also clean other things
a year ago i got my shelf an almost non working ultrasonic for tooth and i started to play with in order modify it to see if it can be used to clean switches form amplifiers ...
not 100% ready yet will need more work but take a look at he results ...
enjoy
well years ago i liked very much the tools he used and actually visited a shop with all the dentist hardware.... beyond tweezers and "fingers" i realized that the bits used to drill the tooth make a wonderful pcb drill ...it can drill high speed drills in the pcb and will not leave flash around the drill ...( ALSO DREMEL COMPATIBLE )
also i learned that now days ultrasonic except cleaning tooth and soldering leftovers might also clean other things
a year ago i got my shelf an almost non working ultrasonic for tooth and i started to play with in order modify it to see if it can be used to clean switches form amplifiers ...
not 100% ready yet will need more work but take a look at he results ...
enjoy
SERVICE PRIMARE A30.2
Never listen to a Primare before ... the specific one come in to the shop clicking protection and had no probs except all protection resistors and fuses blown in the secondary power supply of 48+48 V for the first stage of the amp .
Had in mind that after replacing everything there was going to be some other fault ...well ...i was wrong that was about it looking at the schematic available found out that all voltage was according to specs .
To my understanding he design of this secondary supply is a bit thin and could be made with a bit of durability in mind especially when the rest of the machine is made like a tank !!!
Scope it and had shock number one found a wonderful square wave extending easily to the astronomic number of 100KHZ where the corners was just a bit rounded
scopewise is the first amplifier that beats my P3A ...well actually it beat the sound of it also transparent , quick , real ,tight, brilliant , and extremely analytic .....everything ...name it its there
As about the schematic which i have been looking over and over again to understand exactly how is working and looks pretty simple , the outputs are also nothing exotic 1943-5200 the only "exotic part" is the BC 846 856 inside as a pre driver and that will be a 300MHZ device ..Honestly is the first amplifier that i listen to that features 1943-5200 and sounds that well .
other than the above the amp is a dual mono and inside is seriously made with order ..
enjoy some pics ....and someone will have to study the schematic and tell me what makes this amp so grate
Never listen to a Primare before ... the specific one come in to the shop clicking protection and had no probs except all protection resistors and fuses blown in the secondary power supply of 48+48 V for the first stage of the amp .
Had in mind that after replacing everything there was going to be some other fault ...well ...i was wrong that was about it looking at the schematic available found out that all voltage was according to specs .
To my understanding he design of this secondary supply is a bit thin and could be made with a bit of durability in mind especially when the rest of the machine is made like a tank !!!
Scope it and had shock number one found a wonderful square wave extending easily to the astronomic number of 100KHZ where the corners was just a bit rounded
scopewise is the first amplifier that beats my P3A ...well actually it beat the sound of it also transparent , quick , real ,tight, brilliant , and extremely analytic .....everything ...name it its there
As about the schematic which i have been looking over and over again to understand exactly how is working and looks pretty simple , the outputs are also nothing exotic 1943-5200 the only "exotic part" is the BC 846 856 inside as a pre driver and that will be a 300MHZ device ..Honestly is the first amplifier that i listen to that features 1943-5200 and sounds that well .
other than the above the amp is a dual mono and inside is seriously made with order ..
enjoy some pics ....and someone will have to study the schematic and tell me what makes this amp so grate