Topic: Surplus amps

[obey]

Just sharing with you a picture of my nikko 9095 amp. Sayang lang at may missing siya na button (tape 2 monitor) at medyo nabubura na yung graphix niya.  Pero wala akong masabi sa tunog

[oweidah]

obey, nice nikko ! btw ..mga sir....kamusta po ba ang power consumption (meralco) ng mga surplus sansui luxman etc?...tnx

[sandawa]

i think Wanderlust - one of the good guys you can trust here - is unloading some of his gear including an AU-D907X. even at P10K walang lugi dyan, kung sa US eBay, it would still bid as high as $600. if it's the AU-D907X Decade, lalo na - a Japanese resident here told me there's not much difference between 907X-Decade and first generation Sansui Alpha 907.

[oweidah]

yup ... 2lo laway sansuis circa .70/80s .....saw @ website www.sansui.us 

[oweidah]

sirs.. pwede magpaturo? clueless ako pier gears. i know its a hit or miss thing. sana pwede magbigay kayo tips do's and dont's; step by step procedure on buying surplus amps, etc. what to look for when inspecting the units; then after buying; how to go about cleaning, and the what ifs? where to buy parts (if still available); service centers if meron or refer to competent technicians, hobbyists.
thanxalot...
peace...

[shuttertrigger]

sirs.. pwede magpaturo? clueless ako pier gears. i know its a hit or miss thing. sana pwede magbigay kayo tips do's and dont's; step by step procedure on buying surplus amps, etc. what to look for when inspecting the units; then after buying; how to go about cleaning, and the what ifs? where to buy parts (if still available); service centers if meron or refer to competent technicians, hobbyists.
thanxalot...
peace...

good bunch of questions. these were also my questions at the back of my mind...

[sandawa]

senior (in age) members of the forum have given tips on buying used hifi in previous posts fn this thread. check out posts by guys like av_phile, akyat, narayan, JojoD (mas bata ito!), etc. also a lot of tips in audioslavery's Pinoy Audio board. look for the same names. the more advanced tips such as setting DC offset and bias could be found at Audio Karma's vintage audio forum started by Echo Wars.

[oweidah]

sandawa tnx.

[sandawa]

there are some points in your inquiry that were hardly covered in our previous posts:

- service centers usually don't accept Jap domestic gear but individual technicians do.
- if you know how to test and correctly set the DC offset and bias, there's little chance you'd have a problem wth your surplus amp. most of my surplus amps, at least half a dozen, were over 2 years with me now without trouble.
- use only 100-volt transformers to be sure; (110v transformers could harm your hard-to-find amp)
- consult JojoD for modifications, if he's not busy, he'll help you.

[Lord Foo]

Clueless din ako but I followed the advice of Sir Sandawa and the other Guru's here....I read up on all their posts before buying my first unit at the pier.


100 volts vs. 110 volts.

I totally agree with Sir Sandawa re: 100 volts. My brod's Sony CD Player heated up faster when using 110 volt step down transformers. He had better results when using the flimsy looking 100 volt transformers u can buy at the pier for 200 pesos rather than the heavy black 110 volt transformers costing 500 pesos or more.


DC/BIAS ISSUE.

Also I've followed Sandawa's DC Bias offset advice on two of my units (a pioneer SX1080 and a Sony VFET 5650) and the results were extremely satisfying.  The sx1080 is now running cool as a cucumber after staying in the closet for almost a year due to extreme heat produced by the unit in the past.  The 50 watt SONY TA5650 is now one of my best sounding amps (IMHO). The thing is, u need the manual to calibrate for DC and Bias and some expert advice or you'll burn something in your amp real quick. I am now on a crusade to get Service Manuals on all my amps and check DC  and Bias settings.

[av_phile1]

100 volts vs. 110 volts.

I totally agree with Sir Sandawa re: 100 volts. My brod's Sony CD Player heated up faster when using 110 volt step down transformers. He had better results when using the flimsy looking 100 volt transformers u can buy at the pier for 200 pesos rather than the heavy black 110 volt transformers costing 500 pesos or more.

Japanese household current is strictly 100Vac that is said to have little or no fluctuation.   It is important to have 100V step down transformer, preferrably regulated  types to ensure you get exactly 100V when loaded.  I think you can get better mileage out of surplus gears with this.   Never use 110Vac step down.

[sandawa]

true, although a Japanese trader here in Davao once told me their domestic appliances were made with a tolerance of plus or minus 30% of the voltage rating for a short period of time (a minute or so, he said), it's best to use 100 volts here since even the local transformers rated at 100volts go up to as high as 110 volts in residential areas. based on feedback, Jap made amps run okay for a while in the US (117 to 120V ac) but would eventually burn after an hour or more of use. so, if your Jap amp is plugged in a 110V transformer, you'll have a problem sooner or later.

[wanderlust]

i think Wanderlust - one of the good guys you can trust here - is unloading some of his gear including an AU-D907X. even at P10K walang lugi dyan, kung sa US eBay, it would still bid as high as $600. if it's the AU-D907X Decade, lalo na - a Japanese resident here told me there's not much difference between 907X-Decade and first generation Sansui Alpha 907.

sir,

salamat po. i actually am not very convince in letting this baby go,  hirap, but i have not used it since jan this year, sayang lang kong nakatago at inaalikabukan lang.

posting the innards

[oweidah]

sir sure?

[shuttertrigger]

any updates on surplus amp at pier? 

[gutchy]

mga gurus,

any comments po ba sa NEC A-10 maganda po kya e2 for 2 ch listening..
galing ako sa pier eto lng ung medyo mandang amp dun.. saka ung Onkyo A-701 Integra.. o maghintay nlng kya ako bka my maganda pang dumating.. any suggestion po?

http://www.niji.or.jp/home/k-nisi/a-10.html

[ATJr.]

i am no guru, but one japanese friend told me, products for local jap markets are even better quality than those for export! brands that are popular here in philippines are not that popular in japan!

that nec model looks awsome! from what i can glean from the psu design, it has a second thyristor controlled power supply traffo that reinforces the main traffo when demand for higher output is detected! psu rails are reinforced!

these japs can really come up with innovative techniques in amp building!

[ATJr.]

sir,

salamat po. i actually am not very convince in letting this baby go,  hirap, but i have not used it since jan this year, sayang lang kong nakatago at inaalikabukan lang.

posting the innards

the only difference i can see from your pic is that the Alpha907 used torroidal transformer while yours used an EI transformer. that being the case, you have to option to convert that to 220volts easily! there are many shops doing conversion to 220.

[shuttertrigger]

mga gurus,

any comments po ba sa NEC A-10 maganda po kya e2 for 2 ch listening..
galing ako sa pier eto lng ung medyo mandang amp dun.. saka ung Onkyo A-701 Integra.. o maghintay nlng kya ako bka my maganda pang dumating.. any suggestion po?

http://www.niji.or.jp/home/k-nisi/a-10.html

bro, magkano daw yung NEC A - 10? Yung Onkyo? pareho bang may phono input? Thanks 

[Lord Foo]

The Nisi site says:


Input terminal (level/impedance)

PHONO (MM) 2. 5mV/47k Ω 
PHONO (MC - Low) 80 μ V/10 Ω
PHONO (MC - Hihg) 250 μ V/100 Ω
TUNER 150mV/20k Ω 
TAPE (1 and 2) 150mV/20k Ω 
CD 150mV/20k Ω 
AUX 150mV/20k Ω

[shuttertrigger]

The Nisi site says:


Input terminal (level/impedance)

PHONO (MM) 2. 5mV/47k Ω 
PHONO (MC - Low) 80 μ V/10 Ω
PHONO (MC - Hihg) 250 μ V/100 Ω
TUNER 150mV/20k Ω 
TAPE (1 and 2) 150mV/20k Ω 
CD 150mV/20k Ω 
AUX 150mV/20k Ω

bro, eto ba yung specs ng NEC? pwedeng pwede na ito kabitan ng TT...

[sandawa]

i am no guru, but one japanese friend told me, products for local jap markets are even better quality than those for export! brands that are popular here in philippines are not that popular in japan!

that nec model looks awsome! from what i can glean from the psu design, it has a second thyristor controlled power supply traffo that reinforces the main traffo when demand for higher output is detected! psu rails are reinforced!

these japs can really come up with innovative techniques in amp building!

2ny,

i've been reading your posts and i assure you, even with over 20 years of hi-fi hobby (including some 5 years of trading hifi in Diliman in mid-80s) i'm learning a lot. it's true Japs had cut on expense for their international models to be competitive. even for same number models, those sold internationally were fitted with inferior, cheaper, components. thus, Jap domestic models, now known as surplus here, are of better quality. that's the reason why some Audio Karma veterans envy our stash of cheap Jap vintage gear.

anyway, here's the innard of the Alpha 907 for comparison with the 907X-Decade:

[ATJr.]

bro, eto ba yung specs ng NEC? pwedeng pwede na ito kabitan ng TT...

pwedeng pwede, look, you have a choice of either MM- moving magnet or MC - moving coil pickups for your TT 

[ATJr.]

2ny,

i've been reading your posts and i assure you, even with over 20 years of hi-fi hobby (including some 5 years of trading hifi in Diliman in mid-80s) i'm learning a lot. it's true Japs had cut on expense for their international models to be competitive. even for same number models, those sold internationally were fitted with inferior, cheaper, components. thus, Jap domestic models, now known as surplus here, are of better quality. that's the reason why some Audio Karma veterans envy our stash of cheap Jap vintage gear.

anyway, here's the innard of the Alpha 907 for comparison with the 907X-Decade:

japanese have a different mindset when it comes to selling to their countrymen vis-a-vis selling to foreigners! they are very nationalistic you know.

my japanese friend even told me that SONY is not that hot in japan!

i am able to judge quality of amps by looking at its schematics and innards! at least, those amps sold in saudi targeted for our OFW are of low quality imho. example are sansui's with grey plastic shells, i wouldn't touch them at all! but the sansui G-series are quite good also! so it realy depends on the model, some are lemons but there are GOLDS!

[sandawa]

true, those silver Sansuis sold here in the '80s were hardly distributed in Japan. matindi ang Hapon sir, Sansui's top of the line Alpha series in the int'l market is always one model down compared with their domestic models. Thus, the Alpha 907 series or its equivalent, was never sold internationally, only the Alpha 707 models - re-numbered 911, etc. - were sold in the US and Europe. the few Alpha 907 in the US (Jap domestic models as in our surplus amp) are now bidded at close to $2,000 used (even the Alpha 607, at over $1,000 used). that figure is 7 times the average eBay closed-deal price for the classic Dynaco ST70, which is quite popular here.

BTW, guys, if no one gets Wanderlust's 907x-Decade until next weekend's payday, akin na yan! but i'm giving a chance for others to own it since i already have 3 Sansui TOTLs. if ever, that would be my 4th and probably my 14th amp. hirap dito sa probinsya, walang shops to audition good equipment. thus, the only option is to buy the best ones and decide which ones to hook and which ones to shelve.

[shuttertrigger]

sir lordfoo, how much po yung NEC na nakita nyo? san po banda sa pier? thanks..

sir 2ny, thanks for the reply..

[av_phile1]

true, those silver Sansuis sold here in the '80s were hardly distributed in Japan. matindi ang Hapon sir, Sansui's top of the line Alpha series in the int'l market is always one model down compared with their domestic models. Thus, the Alpha 907 series or its equivalent, was never sold internationally, only the Alpha 707 models - re-numbered 911, etc. - were sold in the US and Europe. the few Alpha 907 in the US are now bidded at close to $2,000 used (even the Alpha 607, at over $1,000 used). that figure is 7 times the average eBay closed-deal price for the classic Dynaco ST70, which is quite popular here.

You may want to skip their models using their proprietary super feedforward circuitry which I heard was quite unstable at high volumes that easily fried the power transistors.  But I suppose those are the international models.  I don't know about similar sansui feedforward designs meant for the local jap market.  I think my old AU-D11 was also a feedforward design.  Though I don't recall sending it to the repair shop often coz I only listen at comfortable levels then.   

[sandawa]

the feedforward technology was Sansui's comparative edge. it speeds up signal flow, which should result in faster musical response compared with other amps (notwithstanding the long winding connectors and electronics components the signal should pass through). 2ny or JojoD could probably explain how it's done, (something to do with bias?) but that technology was pushed to the edge in AU-X1, globally recognized as the "sunugin" amp, which Sansui engineers said was the best amp they produced ever (in late '70s).

i think Sansui used the technology for the silver series, as pointed out by AVphile, but it cautioned buyers not to hook the amps to speakers below 8 ohms. yang ang naging problema ng technicians sa V.V. Soliven dahil maraming speakers, especially US-made pairs bought from  expats' garage sale back then, that ran below 8 ohms average na kinabit sa Sansui silvers (kasama na ako dun - using ARs and JBLs).

anyway, since i have a file here for those technically inclined, below is the innard of AU-X11, which was the revised version of the AU-X1 para hindi na masunog:

[ATJr.]

the feedforward technology was Sansui's comparative edge

it was a nice circuit trick whereby at high frequencies, feedback coming from the output stage (output transistors) were bypassed and feedback  taken from earlier stages, from the VAS(voltage amplifier stage, which btw provides for the full voltage swing of the output transistors) or predriver stages.

rationale behind this is that feedback coming from the output emitters are delayed so that it does no good at higher frequencies! at that time, there was an outcry against global feedback and this provided a nice workaround!

this is one innovation started by the japanese, technics i think it was who pioneered this. of course just as there are fads in clothing, there are also fads in the audio industry!

prof. w. m. leach thought it made a lot of sense so he incorporated it in his latest iteration the leach low tim ver. 4.5

[ATJr.]

You may want to skip their models using their proprietary super feedforward circuitry which I heard was quite unstable at high volumes that easily fried the power transistors.

feed-forward scheme was not responsible for this! output transistors getting fried in the case of sansuis, was a serious design flaw! being mass market, low cost amps, the designers designed the output stage on the assumption that these would not be overworked, meaning it will not be used at high levels and low impedances simultaneously for extended periods!

SOA(safe operating area) of the output transistors were overestimated! where 4pairs are needed, they put in only 2pairs, that is why the output trannies got fried! another reason is rails should have been lower but due to power specs race, they used the transistors near the edge of their ratings.

maybe they got freshmen engineers do the design!