Sony Vfet TA4650 and Yamaha ca1000 DC offset /bias info

lordfoo

lordfoo

Active Member
I just came home with two nice amps for my collection.

A Yamaha CA1000 and a sony Vfet 4650.
Can anyone help provide info on the DC and Bias adjustments for these units. I haven't plugged them yet till i've balanced the settings.

Also, would anyone tell me the difference between the CA1000 and the CA1000III?

The CA1000 i found mentioned in Axel's Vintage Knob ( which made me decide to buy the unit in the first place.) whereas the CA1000III is mentioned int the japanese website.

Oh, I've already acquired a TA5650 and registered it at the vintage knob. I intend to register the TA4650 also if it is rare enough.
 
Register to hide this ad
lordfoo,

CA-1000III = CA-1010
1000III was the moniker for the japanese market, 1010 for the rest of us.
Click the "ZN" button on the 1010 page ; IIRC, Zeljko's mentions proper bias current in his description.

I own a CA-1010 but it now needs basic TLC which I unfortunately don't have time to carry on...

All V-FETs are rare enough to be registered :)
 
lordfoo said:
...Also, would anyone tell me the difference between the CA1000 and the CA1000III?...
Click to expand...

your southern neighbor's Yamaha CA-1000III:

ca3.jpg


ca4.jpg


ca5.jpg
 
my you have great gear sandawa!
how are the B-3's V-FETs doing?

here are two old shots of my own CA-1010 - this one came from Switzerland. Seems to be some differences around the output drivers... little boards added for thermal sensing/protection or something of the kind?
 
thanks axel, the B-3 is doing okay. it's part of a bi-amp system consisting of a WiredState tube pre-amp and a Sonic Impact T-amp also used as power amp. the B-3 drives the mid/low units of my KEF 101 series 2 and the T-amp handles the high-frequency units.

that system integrates the valve sound, vintage solid state V-FET technology, and the sonic characteristics of the digital chip amp.
 
Last edited:
Sir Sandawa,

For the pair of meters alone, I like your CA1000III better than my CA1000.
:)

I have a soft heart for meters.
 
here are three from a japanese website - I still haven't found a proper catalog image for the B-3, hence its absence from TVK's V-FET section so far. I guess patience is a virtue :)
 
inductor said:
hi
i have service manual if you want any details
Click to expand...

Hi inductor,

I would appreciate it very much if you can provide me a soft copy of the service manual.

thanks,
Foo
 
After almost a year in storage, i pulled out the Yamaha CA1000 and hooked it up with a Sony CDP 337ESG, A Sony SA50ES tuner and a Dual 505.2 Turntable with a pair of AR2a speakers.

The amp rocks with the AR2as.

I hooked it up with a pair of Yamaha NS690 speakers and the results were even better. Mids and high were as good as the Ar2a but the bass is much much better.
 
Last edited:
Update:

Yamaha CA1000

The CA1000 is now in storage, replaced with a Sansui AUD707xdecade. I realized later that the AR2a is actually an AR2ax with the two mid range drivers. These are in the speaker A outlets. A pair of Onkyo speakers are in the speaker B outlets. Why store the yammy? The Sansui kicked its ass. Maybe there's a problem with the ca1000 capacitors or something. I still have to find service manuals for the ca1000.

SONY TA4650 VFET

Meanwhile the 4650 VFET is still not being used. I've sent it to my brother technician for bias adjustments, diode replacements along with my 5650. It is still with him since after the diode replacements, capacitor replacements and bias adjustments, the pre-amp turned out to be problematic. The 4650's power amp hooked up with another preamp however sounded very good.

SONY TA5650 vfet matched with Yamaha NS1000m.

The 5650 came back recently and is now singing sweet harmony with a pair of NS1000m's. The combination is very very sweet. If you have both units, you have to match them up.

Two CD's i used as test disks, brought out the best in the yammy+sony combination. Sara K. and chris Jones, Live in Concert recording and "The Latin Jazz Sound". Sara's Guitar and voice came out very very cleanly . You have to check out this two recordings. They are fantastic.

I also used the great guitar Cd entitled, 'Concierto de Aranjuez. Joaquin Rodrigo." .. Great indeed but the first 2 CDs seemed to match better the VFET-NS1000m combination and my tastes. Also, the tracks gets silent and then very very loud suddenly which is okay for dramatic effects but not for my neighbors' ears.

The combination is going to stay very very long in my room.
 
lordfoo said:
Update:


SONY TA4650 VFET

Meanwhile the 4650 VFET is still not being used. I've sent it to my brother technician for bias adjustments, diode replacements along with my 5650. It is still with him since after the diode replacements, capacitor replacements and bias adjustments, the pre-amp turned out to be problematic. The 4650's power amp hooked up with another preamp however sounded very good.
.
Click to expand...

Hi Lordfoo,

I've recently acquired a 4650 then ran a DC-offset checks. It shows difference between two channels. One shows 12mV, the other shows 1.5v (without power transistors). Please help indicate possible problem(s). Thank you
 
Make sure you do not use a variac to power up the 4650. The service manual is available on hifiengine.com.

The manual states to set bias at 75mv. Many say this is too high. I bias my 4650 at 50mv and do not notice any distortion. Search AK as someone else tested distortion on this amp at various bias settings and came to the conclusion 50mv is fine.

Also, Echowars is one of the resident experts on Vfet amps.

Hope you get it running. Mine is still in my main rig, has been since 1980.
 
You must log in or register to reply here.
Back
Top Bottom