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CA-F1 vs AU-919 (or 717) preamp

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1979

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Just curious if anyone could provide details on how the CA-F1 by itself compares to the preamp section of an AU-919 (or 717)? In other words, if an AU-919 (717) was used as a preamp only and connected to a BA-F1, would it basically still sound the same as a CA-F1 connected to a BA-F1? I imagine the Sansui svce manuals would indicate how many components/circuits may be similar between the CA-F1 & AU-919. Just wondering how much they may have in common since they were produced at the same time in '79/'80.

One nice thing about using the 919 as a preamp to the BA-F1 is the 919 has the much larger click-stop volume control knob, and some extra functions such as the Jump, Muting, Tape copy switches, that the CA-F1 lacks.

I was also thinking that an AU-919 might be safer to use in preamp mode if someone hasn't had the restoration work done on it to correct the design flaw that is known to damage the original NM 1012 transistors.
 
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1979 said:
Just curious if anyone could provide details on how the CA-F1 by itself compares to the preamp section of an AU-919 (or 717)? In other words, if an AU-919 (717) was used as a preamp only and connected to a BA-F1, would it basically still sound the same as a CA-F1 connected to a BA-F1? I imagine the Sansui svce manuals would indicate how many components/circuits may be similar between the CA-F1 & AU-919. Just wondering how much they may have in common since they were produced at the same time in '79/'80.
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I don't know the answer to this, but I suspect that the 'voicing' of the power amplifier in use would play a major part in what you hear. Note that in normal use, (Jump switch disengaged, & not using a phono input) there is no 'pre-amp' as such in the AU-919 - the input from a tuner or CD player is fed directly to the power amp.

1979 said:
One nice thing about using the 919 as a preamp to the BA-F1 is the 919 has the much larger click-stop volume control knob, and some extra functions such as the Jump, Muting, Tape copy switches, that the CA-F1 lacks.
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A larger volume control can be nice. However, the click stops can prevent you from setting a precise level requiring the use if the muting switch to give finer control over the volume increments. The 'Jump' function is an odd-ball in my opinion - engaged it drops the signal by 16dB. And if engaged and forgotten about, dissengaging it with the volume turned up to compensate, can be an 'interesting' experience. Tape copy switches - of somewhat limited use these days.

1979 said:
I was also thinking that an AU-919 might be safer to use in preamp mode if someone hasn't had the restoration work done on it to correct the design flaw that is known to damage the original NM 1012 transistors.
Click to expand...

No, an un-reconditioned AU-919 used as a pre-amp only, will be just as susceptible to damage as when used as a whole amplifier.

Lastly, I am puzzled by the questions and reasons why you might want to do this. From all I have read, the CA-F1 & BA-F1 combination is an absolutely magnificent setup - one of the finest sounding vintage pre-amp / power amp combinations there is.
 
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Actually, I already have two AU-919's, and a BA-F1 & CA-F1. The reason I brought up my questions: Although I enjoy the 919's very much and they are truly great amps, I haven't had the mod/restoration work done on them. I wish I could, but from what Ive heard, the $ cost to have it done is rather expensive (let alone the cost of one, but I have two- which involves extra packing/shipping & return shipping costs as well).

Its hard to enjoy the 919 when its played, as I'm worried the amp can go Poof! at anytime and the NM 1012's are 'history'...

I believe the BA-F1 also has the same 1012's, and would need the mod as well to correct the design flaw. Thus, if I cant afford to have all of these amps fixed, I was thinking to just keep the BA-F1 and sell the AU-919's, and perhaps from the sale, use the $ to have the work done on the BA-F1.

The CA-F1 is pushing 35 yrs old so I wouldn't be surprised if it too could use some restoration to replace old components. Its a nice preamp, but the large depth and very small height result in a front panel that has somewhat small knobs- not that its sooo bad, but the larger ones on the 919 are more appealing, thus the idea to use the 919 as a preamp, in which case I could justify still keeping & using it (if it was safer in preamp mode, to not have the 1012's go kaput).
 
Ah - now I see... AFAIK the BA-F1 is not nearly so prone to self immolation as the AU-919, but un-reconditioned you won't be hearing it at its best.

If I were in your position - much as I like the AU-919, I would sell one and use the money to fund the re-con of the BA-F1. Then use the BA-F1 / CA-F1 combination, then have either the CA-F1 or the AU-919 re-conned when you can afford it - and so on.

I have an AU-919 which I have reconditioned apart from the main PSU capacitors - these are definitely on the to-do list when I can afford it. There are one or two other things that I would like to revisit in the '919 at the same time to properly finish it off, but at the moment I am enjoying it very much.
 
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The BA-F1 is just as prone to destroying itself. The Black Mica caps plague it as well as the CA-F1. I have yet to see a CA-F1 come through here that does not have a blown phono channel as well. They are all time bombs that need servicing by a competent tech to be reliable. However, once done.... They are fantastic!!

Here is what a BA-F1 should look like :D

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1979 said:
Actually, I already have two AU-919's, and a BA-F1 & CA-F1. The reason I brought up my questions: Although I enjoy the 919's very much and they are truly great amps, I haven't had the mod/restoration work done on them. I wish I could, but from what Ive heard, the $ cost to have it done is rather expensive (let alone the cost of one, but I have two- which involves extra packing/shipping & return shipping costs as well).

Its hard to enjoy the 919 when its played, as I'm worried the amp can go Poof! at anytime and the NM 1012's are 'history'...

I believe the BA-F1 also has the same 1012's, and would need the mod as well to correct the design flaw. Thus, if I cant afford to have all of these amps fixed, I was thinking to just keep the BA-F1 and sell the AU-919's, and perhaps from the sale, use the $ to have the work done on the BA-F1.

The CA-F1 is pushing 35 yrs old so I wouldn't be surprised if it too could use some restoration to replace old components. Its a nice preamp, but the large depth and very small height result in a front panel that has somewhat small knobs- not that its sooo bad, but the larger ones on the 919 are more appealing, thus the idea to use the 919 as a preamp, in which case I could justify still keeping & using it (if it was safer in preamp mode, to not have the 1012's go kaput).
Click to expand...

Having worked at the sansui service here in greece , i"ve never heard the 919 going into oscilation , with the known consequences.
AU-X1 was known for that behavior. Anyway , if anyone is interested , there are some nma , for sale in a known place , pm me if you want.

Also the big psu caps should be changed in sight , along with all electrolytics in those amps. That goes for hyperion also.
Don"t be afraid your 919 will go pooof , just make shure the bias is ok , and at least the huge caps in psu are at least decent.I mean not dryied out.
As far as circuit design 919 is not far away from ca-f1, if at all.
 
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Nice photos!, appreciate all the good info. Yeah..., although its nice to have all these great Sansui amps, it can a curse as well as a blessing, to have them restored due to their age & various issues and the $$ needed to do that (especially when you're already struggling financially), I still need to have my CA-3000 serviced for the 'feed-thru' problem, a common issue on this otherwise superb preamp.
 
I completely recapped my 919 with the help (advice) of echowars and others here on AK. I couldn't have done it without these guys advice.
Only those big oval caps haven't been done. Maybe one day I'll do them.
For now,...it's awsome!:yes:
 
ghamilton said:
Only those big oval caps haven't been done. Maybe one day I'll do them.
For now,...it's awsome!:yes:
Click to expand...

The procedure has been posted a few times, but I'll post my AU-919 big oval caps change when I do them - unless you beat me to it :)
 
Anyone care to comment on the ops questions 7 years later? How does the ca f1 compare to the 919 as preamp? Very hard to find a ca-f1 these days.
 
pjrengineer said:
Very hard to find a ca-f1 these days.
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There is one for sale right now on that website - if you are interested.
pjrengineer said:
Anyone care to comment on the ops questions 7 years later? How does the ca f1 compare to the 919 as preamp?
Click to expand...
I imagine they would be very similar as the circuitry is almost identical, with perhaps a nod to the CA-F1 for somewhat more sophisticated MM Head Amp and more attention to PSU filtering.
 
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Hyperion said:
There is one for sale right now on that website - if you are interested.
I imagine they would be very similar as the circuitry is almost identical, with perhaps a nod to the CA-F1 for somewhat more sophisticated MM Head Amp and more attention to PSU filtering.
Click to expand...
The one on the website has some issues with the mc circuit.
 
One on "that website" right now has had all the MC preamp circuit components stripped, so has no functional MC preamp. Likely could have the needee parts repopulated (PCB is there) to make it work again. It is also stated to be a 100V version, and has some cosmetic issues. Price is almost reasonable, but personally I'd shy away from one that has been treated this way. Conversely, it is likely the least expensive CA-F1 you'll find without a time machine to go back ~10 or more years before the pricing mania really set in.
 
I've just seen this thread now. The CA-F1 with no MC section that you saw is mine. I previously bought it from Canada with condition "phono not working". When it arrived I find the MC section burned out and then stripped. Checking the profile of the seller and I can see they are adept at restoration/servicing, so they should have told me the full situation. They did not reply to communication so I left negative feedback.

Moving on though, I've seen other CA-F1 with phono section burned out. There are 24 JFETs in the MC section alone (!) that are now hard to come by, so they sometimes seem to be harvested even when working :(.

I have not restored the unit yet, sadly, but I'm using it after thorough check-up. Aside from the MC section it's a stellar unit. It's a lovely diamond-diff dual fet input preamp with cascoding and darlington SEPP. As Nelson Pass says, 'class A' is easy to market' but cascoding works.

I also own a 120V CA-F1, but I use the 100V unit (with a variac). Why? The Japanese CA-F1 actually has slightly better power supply setup (mainly bigger reservoir) and a few bits inside are also nicer.
 
smurfer77 said:
I've just seen this thread now. The CA-F1 with no MC section that you saw is mine. I previously bought it from Canada with condition "phono not working". When it arrived I find the MC section burned out and then stripped. Checking the profile of the seller and I can see they are adept at restoration/servicing, so they should have told me the full situation. They did not reply to communication so I left negative feedback.

Moving on though, I've seen other CA-F1 with phono section burned out. There are 24 JFETs in the MC section alone (!) that are now hard to come by, so they sometimes seem to be harvested even when working :(.

I have not restored the unit yet, sadly, but I'm using it after thorough check-up. Aside from the MC section it's a stellar unit. It's a lovely diamond-diff dual fet input preamp with cascoding and darlington SEPP. As Nelson Pass says, 'class A' is easy to market' but cascoding works.

I also own a 120V CA-F1, but I use the 100V unit (with a variac). Why? The Japanese CA-F1 actually has slightly better power supply setup (mainly bigger reservoir) and a few bits inside are also nicer.
Click to expand...
I have a 120v and it’s my go to preamp for testing new gear on my bench, blasting in the garage, or traveling with gear. It is so perfect. It pairs great with everything I’ve tried.
 
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