Service kenwood ka 50
just another comercial product with nothing realy special to talk about ...
yet again the same story ... all caps replaced all switches and pots cleaned nothing to tune in the amplifier japanese designer of these and previous "brown" models of kenwood was so sure about the parts that VBE is runing from a standard resistor and no trimmer
often depenting o the costumer and the use of the product i replace those with a trimmer in order to beef the bias up to so persentage to gain bitsof quality ...
even though musical and quiet amplifier ... still is a lower than average design of the 80s at least compairing to now days machines
remains both negative and positive that all this kenwood family uses a passive tone control that uses signal from the outpout to operate ....positive since with a proper and easy speaker can produce nice sonics and negative since long cables and strange loads will almost make it unstable
reagards sakis
just another comercial product with nothing realy special to talk about ...
yet again the same story ... all caps replaced all switches and pots cleaned nothing to tune in the amplifier japanese designer of these and previous "brown" models of kenwood was so sure about the parts that VBE is runing from a standard resistor and no trimmer
often depenting o the costumer and the use of the product i replace those with a trimmer in order to beef the bias up to so persentage to gain bitsof quality ...
even though musical and quiet amplifier ... still is a lower than average design of the 80s at least compairing to now days machines
remains both negative and positive that all this kenwood family uses a passive tone control that uses signal from the outpout to operate ....positive since with a proper and easy speaker can produce nice sonics and negative since long cables and strange loads will almost make it unstable
reagards sakis
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Service alesis ra 500
ALESIS RA 500...
dont really know if this is real alesis product or some other factory that have some arangement with Alesis
cheap small amplifier ( size and power ) sound is quiet good for a classic efp /Vi limmiter design .... amplifier is very balanced nothing is too much or too litle ...Vi limmiter works properly for this type of application ...it kills sonics ...but at least it does it carefully
the abilty to drive low loads is very lilte
cooling is done with external heat sinks only ..bearly enough
pcbs inside are boiling if stressed
generally a marginal design ...
capacitance is fairly low for this amp ....
at least it has a brand name and a low prize
thermal stress produce soldering issues ...resistors driver and protector was blown replaced and go ...
ALESIS RA 500...
dont really know if this is real alesis product or some other factory that have some arangement with Alesis
cheap small amplifier ( size and power ) sound is quiet good for a classic efp /Vi limmiter design .... amplifier is very balanced nothing is too much or too litle ...Vi limmiter works properly for this type of application ...it kills sonics ...but at least it does it carefully
the abilty to drive low loads is very lilte
cooling is done with external heat sinks only ..bearly enough
pcbs inside are boiling if stressed
generally a marginal design ...
capacitance is fairly low for this amp ....
at least it has a brand name and a low prize
thermal stress produce soldering issues ...resistors driver and protector was blown replaced and go ...
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i dont see the reason to ask me ...i am not the desiger of the P3A .... you may ask the designer directly for that
www.sound.westhost.com
www.sound.westhost.com
You may be interested to know Sakis that this amp is same as Behringer EP500, must be same Chinese factory makes them and different case and badging.
Thank you for the description as it is useful to know. I know a lot of people who think the EP500 is some kind of wonder amp, but you have revealed it's true colours and some that I suspected for a long time.
thanks richie00boy.... compaired that i have repaired almost 600 amps the latest 5 years and only one ( 1) behringer i wouldnt know ... but i will look in to it since i am not really sure for it
thanks though
your comment about a500 from behringer and RA 500 from alesis made me do a litle searching richie00boy and after i got a schematic for both and inside pictures of both i can guarantee you that are not only two absolutelly diferent products but also that behringer is by far better
alesis features normal trafo- behringer is torodial
alesis features 2X10.000 mfd for the all amplifier one bridge and powersupply
behringer features 2x10.000 mfd +seperated rectifier per board
behringer features 2 leyer pxb while alesis features piggy boards to fit everything in a 3U short box
behringer uses 2U box that is more dee than alesis
true the front side is probably made by the same designer
regards sakis
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Service A.C Magnum Class A
i am not in tha Class A thingy ...i am just a classic 2SA1302 class AB person ...but bussines is bussines and i have to repair that also from time to time as we speak my first krell is on the way ....
ok doki the machine comes in with a number of problems but most that the amplifier shut down out of the blue for no reason and as the costumer said it just happend after the amplifier has been upgraded from another technician ....
striping down the litle brit is not an easy task since to be able to have acces down under you need to unscrew everything and that of course means that you need to redo all the mechano work replace or alline insulators whixh happens to be plenty ...
To make long story shorter the amplifier has been upgraded by some tech guy that replace the cables from the pcb to the binding post ( about 20 cm ) from the original cable with VDH cables and beefed the idle enough to boil all the solderings inside the amplifier
Results local regulators for the first stage of the amplifier totaly disoldered and afew resistors boiled but other than that no other problems
after that discovered some factory mistake ...in chanel A source resistors was 0.33R while in the other channel it was 0.22r
replaced the broken , did the soldering and the mechano and then bias the amplifier to something more earthy and listen to it ....
terrible expirience .... the sound was "mufled " treble was confusing midle was perfect , bass, sound stage and depth was simply upsent ...just wasnt there ...the amplifier had a terrible low end and seemed to me that was working with some compressor behind it
i simply didnt bother to look why costumer was more than happy and that was the end of story ...if anybody bothers to ask if i find the sound of a P3A better i will answer +10.000 times better by far
here is some pictures of the litle cr@@p
i am not in tha Class A thingy ...i am just a classic 2SA1302 class AB person ...but bussines is bussines and i have to repair that also from time to time as we speak my first krell is on the way ....
ok doki the machine comes in with a number of problems but most that the amplifier shut down out of the blue for no reason and as the costumer said it just happend after the amplifier has been upgraded from another technician ....
striping down the litle brit is not an easy task since to be able to have acces down under you need to unscrew everything and that of course means that you need to redo all the mechano work replace or alline insulators whixh happens to be plenty ...
To make long story shorter the amplifier has been upgraded by some tech guy that replace the cables from the pcb to the binding post ( about 20 cm ) from the original cable with VDH cables and beefed the idle enough to boil all the solderings inside the amplifier
Results local regulators for the first stage of the amplifier totaly disoldered and afew resistors boiled but other than that no other problems
after that discovered some factory mistake ...in chanel A source resistors was 0.33R while in the other channel it was 0.22r
replaced the broken , did the soldering and the mechano and then bias the amplifier to something more earthy and listen to it ....
terrible expirience .... the sound was "mufled " treble was confusing midle was perfect , bass, sound stage and depth was simply upsent ...just wasnt there ...the amplifier had a terrible low end and seemed to me that was working with some compressor behind it
i simply didnt bother to look why costumer was more than happy and that was the end of story ...if anybody bothers to ask if i find the sound of a P3A better i will answer +10.000 times better by far
here is some pictures of the litle cr@@p
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service Luxman LV 110
nice simple luxman come in to the shop for service a classic story ...no damages ...all caps to be replaced... a bit if mechano since all was dryied up arround the transitors ... tune the idle and good to go
a bit of cleaning here and there and other than that absolutelly nothing else...
I have seen wonderfull production luxman thatsounded superior but this one wasnt one of them .... low power , but better ends ( even better from my previous post ) the amplifier had plent of high and a nice pre amp but wasnt clean enough ...
expected from the prize tag of this model ... i think that it was a cheapy
on the negative i will say that there is no real protection and luxman in order to avoid power on off noises switches the speakers on off with the same switch that powers on of the all machine ...very cheap i think
on the other hand a bellow average amplifier can serve a kitchen system ...
here is a picture
nice simple luxman come in to the shop for service a classic story ...no damages ...all caps to be replaced... a bit if mechano since all was dryied up arround the transitors ... tune the idle and good to go
a bit of cleaning here and there and other than that absolutelly nothing else...
I have seen wonderfull production luxman thatsounded superior but this one wasnt one of them .... low power , but better ends ( even better from my previous post ) the amplifier had plent of high and a nice pre amp but wasnt clean enough ...
expected from the prize tag of this model ... i think that it was a cheapy
on the negative i will say that there is no real protection and luxman in order to avoid power on off noises switches the speakers on off with the same switch that powers on of the all machine ...very cheap i think
on the other hand a bellow average amplifier can serve a kitchen system ...
here is a picture
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Thank you for the update sakis. However I made a mistake, it was the Behringer A500 I meant. The EP500 is indeed a better quality amp and more expensive.
Interesting comments on the class-a amp. Class-ab rocks
you didnt make any mistake the all subject and pictures is from the A500 ....
as about commnents regarding the p3A in class i am probably the wrong person to be asked sine i know nothing about it
as told the P3a is very happy with 30-50 ma and my standard version is about 120
I will ring a bell though once more that my son's version that was created with BD829-30+2SA1302-3281 plays so good and by far better than BD139-140 while still is biased very low like 40-50 ma
kind regards sakis .....
hei ...richie00boy...since you are UK located it could be a nice idea to pick up a phone and find out for us the whereabouts of AC Magnum and if possible a schematic ....just for the record
( AC Magnum is a proper name though for this machine since it could be easilly used as an AC ( airconditioner) but only for winter season )
( AC Magnum is a proper name though for this machine since it could be easilly used as an AC ( airconditioner) but only for winter season )
servive nikko 8085
i love NIKKO products .... each and everyone of them i lay my hands on was a masterpiece on its class
here is this model 8085 ..integrated amplifier with a tuner standard repair and no upgrades for that one .... will mean total cleaning tuning and recaping
after that and especially for the specific model that seems that is made especially for germany which of cource means stupid 5pin DIN plugs everywhere and even more stupid .- speaker plugs
after the repair a wonderfull very sensitive and suprizinglly sensitive tuner come up ... before the repair aft functions and a bit of frequency roll of problems have been fixed with simply replacing the caps .... no coil or cap to be touched resulting an extremlley acurate tuner
add to this that in radioamps the tuners often do not produce decent sound but not for this one ... the tuner actually sounded wonderfull
the preamplifier section sound German ... tone control will add wonderfull sonics both for bass and treble ... bit coloury but that is ok i think for this style of amplifier loudness and phono stage is arround the same philosophy
wonderfull simple amplifire section original powerfull toshibas will guaranty more than 60 heavy real watts per chanel coming from a big trafo and big caps ...relativelly big heatsink will also ensure that amp will run cool even if pushed .... excellent dula transistor in the input and wonderful control of the idle and ofset ////
it has been fun to work with a very nice japanese amp especially made for the german ...odd combination
here is a picture
( please also keep in mind that i keep schematics for most of the equipment i repair and also have very good memory if you need just e mail me )
i love NIKKO products .... each and everyone of them i lay my hands on was a masterpiece on its class
here is this model 8085 ..integrated amplifier with a tuner standard repair and no upgrades for that one .... will mean total cleaning tuning and recaping
after that and especially for the specific model that seems that is made especially for germany which of cource means stupid 5pin DIN plugs everywhere and even more stupid .- speaker plugs
after the repair a wonderfull very sensitive and suprizinglly sensitive tuner come up ... before the repair aft functions and a bit of frequency roll of problems have been fixed with simply replacing the caps .... no coil or cap to be touched resulting an extremlley acurate tuner
add to this that in radioamps the tuners often do not produce decent sound but not for this one ... the tuner actually sounded wonderfull
the preamplifier section sound German ... tone control will add wonderfull sonics both for bass and treble ... bit coloury but that is ok i think for this style of amplifier loudness and phono stage is arround the same philosophy
wonderfull simple amplifire section original powerfull toshibas will guaranty more than 60 heavy real watts per chanel coming from a big trafo and big caps ...relativelly big heatsink will also ensure that amp will run cool even if pushed .... excellent dula transistor in the input and wonderful control of the idle and ofset ////
it has been fun to work with a very nice japanese amp especially made for the german ...odd combination
here is a picture
( please also keep in mind that i keep schematics for most of the equipment i repair and also have very good memory
if you need just e mail me )Attachments
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Service pioneer sx-450
HERE is a nice machine ...as simple as it can be ...low in power nice preamp small sweet amplifier ...unfortunatelly quasi ( i dont know why i state this as a minus but i do )
had the chance to listen to it before and after the thing was half dead ...over used, all capacitors inside completely dried out, sounded very mufled with a bad bandwidth and very telephone sound ...no ends at all
complete recaping tuner also ...very stable and accurate but bit hissy ... expected i think for a tuner that old and that simple
still a very sweet litle machine could be a perfect secondary system ... or if pre and main seperated the main amplifier could perform superb with a pair of sensitive speakers
selector section kinda noisy crosstalk figures are probably bad ...but with only one active source thing is quiet ok
beyond caps replaced did some litle things with the inputs since those was filetred with ceramics but also with very big values that reduced bandwidth .... reasonable for the time to protect from RF injected in but now days sources areby far better so it was good to let the amp free a bit more to enjoy some high frequencies
Costumer liked to have the speaker binding post replced ... so we did
here is some pictures
HERE is a nice machine ...as simple as it can be ...low in power nice preamp small sweet amplifier ...unfortunatelly quasi ( i dont know why i state this as a minus but i do )
had the chance to listen to it before and after the thing was half dead ...over used, all capacitors inside completely dried out, sounded very mufled with a bad bandwidth and very telephone sound ...no ends at all
complete recaping tuner also ...very stable and accurate but bit hissy ... expected i think for a tuner that old and that simple
still a very sweet litle machine could be a perfect secondary system ... or if pre and main seperated the main amplifier could perform superb with a pair of sensitive speakers
selector section kinda noisy crosstalk figures are probably bad ...but with only one active source thing is quiet ok
beyond caps replaced did some litle things with the inputs since those was filetred with ceramics but also with very big values that reduced bandwidth .... reasonable for the time to protect from RF injected in but now days sources areby far better so it was good to let the amp free a bit more to enjoy some high frequencies
Costumer liked to have the speaker binding post replced ... so we did
here is some pictures
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Service luxman l3
poped in the shop for service and if possible som kind of upgrade ...eventhough is the first time that i open one of these i have heard before from other costumers that these are simply nice small amps like all of them of luxman at the time ( or most of them) ( i will have to exclude all STK3082 models 
)
Any way from various owmers i have heard that the amp is fine but kinda of dark especially in high frequencies
belive it or not this particular ruther cheap comercial amplifier is properly builted or better say properly designed cause i think that on the way many things went wrong ...
problems located in three areas
one that capacitors electrolytics in the amplifier board are placed onatop horizontally and beyond the fluid issue that concetrates in one are and loose capacitance having caps onatop is a temperature collector ...
two
that way too many ceramics are involved in signal path and divisions of the amplifier so beyond thebtotal recaping ive done the favour to replace input with MKT filter with silver mica and miller caps here and there with styroflex caps ...
three
and worst i would say was the vbe transitors of both chanels that evnthough had the proper size soldered in the proper area to sense temperature actually was never installed in the right place ( as seen in photos ) and to my understanding that was simply an assembly error that manage to convert the white cream to almost dust from time and temeprature combination
Result that amplifier was overheating and had thermal runaway which was an issue that we fixed
Amplifier now measures and sounds by far better ...it is a quiet amplifier concidering the way and tiome it was made even though ahs seperated bass and treble controls these remain quiet accurate offset is ultra low 0.001 and with a very good adjustment and also biass was quiet high for this type of amp but after the repair was extremelly stable ...
since in the some time in the feature i will see on of these again it will be interesting to notice if they are made proprely in the VBe area and my piece had simply an assembly error
here is some pictures
poped in the shop for service and if possible som kind of upgrade ...eventhough is the first time that i open one of these i have heard before from other costumers that these are simply nice small amps like all of them of luxman at the time ( or most of them
) ( i will have to exclude all STK3082 models )Any way from various owmers i have heard that the amp is fine but kinda of dark especially in high frequencies
belive it or not this particular ruther cheap comercial amplifier is properly builted or better say properly designed cause i think that on the way many things went wrong ...
problems located in three areas
one that capacitors electrolytics in the amplifier board are placed onatop horizontally and beyond the fluid issue that concetrates in one are and loose capacitance having caps onatop is a temperature collector ...
two
that way too many ceramics are involved in signal path and divisions of the amplifier so beyond thebtotal recaping ive done the favour to replace input with MKT filter with silver mica and miller caps here and there with styroflex caps ...
three
and worst i would say was the vbe transitors of both chanels that evnthough had the proper size soldered in the proper area to sense temperature actually was never installed in the right place ( as seen in photos ) and to my understanding that was simply an assembly error that manage to convert the white cream to almost dust from time and temeprature combination
Result that amplifier was overheating and had thermal runaway which was an issue that we fixed
Amplifier now measures and sounds by far better ...it is a quiet amplifier concidering the way and tiome it was made even though ahs seperated bass and treble controls these remain quiet accurate offset is ultra low 0.001 and with a very good adjustment and also biass was quiet high for this type of amp but after the repair was extremelly stable ...
since in the some time in the feature i will see on of these again it will be interesting to notice if they are made proprely in the VBe area and my piece had simply an assembly error
here is some pictures
Attachments
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