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List of capacitor coupled solid state receivers and integrated amplifiers

GMuk said:
On the receiver side I can add the L&G (Luxman) R3400 and R3600.
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I recall seeing a spec sheet somewhere for the L&G Luxman series that listed their THD as about 0.1%. That seems very low for a cap coupled design. Any further verification?

I'll be looking myself and will plan on adding them, and maybe other receivers from that line, the next time the list is updated. Thank you!
 
GyroTuner said:
I recall seeing a spec sheet somewhere for the L&G Luxman series that listed their THD as about 0.1%. That seems very low for a cap coupled design. Any further verification?

I'll be looking myself and will plan on adding them, and maybe other receivers from that line, the next time the list is updated. Thank you!
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I have never been able to find a service manual or schematic for either of these, but the board layout with large capacitors on the outputs led me to think they were capacitor coupled.

IMG_20230416_153838469.jpg IMG_20230416_153852087.jpg

I did manage to find a brochure in German that gave some distortion figures:
upload_2023-4-16_17-47-35.png
 
Nice finds, especially the brochure, there are some other pictures here: https://www.circuitsonline.net/forum/view/60584

Only one big filter cap suggests a single rail power supply. There is an empty hole in the chassis for another filter cap but they probably just used that same chassis for other similar products.

And this thread also suggests it is cap coupled: https://audiokarma.org/forums/index.php?threads/luxman-group-l-g-r-3400.850912/

However, those low distortion figures still raise a little bit of doubt. It would be nice to see a schematic.
 
FWIW - As well as having a single large filter cap, a quick check would be to measure voltages on the collectors of the output transistors. If both are NPN, they will have the supply voltage and half the supply voltage on them. If NPN and PNP, they NPN will have the positive rail and the PNP will have zero volts on it.
 
sregor said:
FWIW - As well as having a single large filter cap, a quick check would be to measure voltages on the collectors of the output transistors. If both are NPN, they will have the supply voltage and half the supply voltage on them. If NPN and PNP, they NPN will have the positive rail and the PNP will have zero volts on it.
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Thanks. I had a look at this. The R3400 has 4 x SD155 NPN output transistors and the R3600 has 4 x SD188A NPN. I am not getting voltages as mentioned in your reply though. I get 30V on one transistor on the R3600, but 0V on the other per channel. The R3400 is similar but around 25V. Both were bought as faulty for repair so that may be one of the issues with them. Both pass the DBT and the displays light up.
 
GyroTuner said:
I believe they are and will include them in next list update. Thank you.
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might wanna include a note next to the str6046 as the "a" model is not. such as:

str-6046(non "a") ...just to avoid confusion and unnecessary questions;)

you are doing a great job keeping up with this.:thumbsup:
 
Also I have read that there are unobtainable parts on the A units as well. Thats why there are many for sale on the bay. By the way I have collected 6 cap coupled units this past month. I going out to the deep end with this cap coupled thing. I wish we could get a good Transformer coupled list going as well. I tried to start one but my thinking is there isnt alot of folks that were alive yet during those times. Lol
 
Thank you all for the feedback. I made a few updates to the list, bringing the totals to 285 receivers and 122 integrated amplifiers.

Unfortunately, it appears that I can't edit the first post in this thread to include the latest list. That feature seems to have been disabled after the site upgrade. However the latest list, dated December 6, 2023, is attached to this message.
 

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@bhairavi, you are welcome.

Congratulations on the Sansui 4000 - that's a nice receiver. I'm a big fan of the old Sansui cap-coupled integrateds, especially the AU-222 and AU-777A. But you almost can't go wrong with any Sansui!
 
here's one

quadraflex 085r...8.5wpc


drun tunes plus mini q 104.jpg

it uses 2 chips, each bridged with an output cap on each output of each chip(4 caps)


005.jpg


Inked012_LI.jpg

* = output coupling caps.



drun tunes plus mini q 107.jpg

i don't consider myself a collector but here i am.
 
I wanted to sort by power, see below. Then I also wanted receivers and amps in the same list so I wouldn't have to scroll back and forth between the two lists to check a particular Kenwood or Sansui, for example, so that is the next post.
 

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That Quadraflex is really cool. I bought out the repair Depot of Quadraflex in the 1980's.

To add to the capacitor coupled amplifiers.

Dynaco ST-80.

Dynaco ST-120.

Really good sounding amps. Had a made in England receiver that was also cap coupled Dynamax or something had a picture of Queen Elizabeth on it...

Most of these amps use a design called "Totem Pole" found in the early RCA and GE transistor manuals.

Often used with a driver transformer and Germanium transistors.
 
Thanks to everyone for their contributions. The sorted lists are nice.

The Quadraflex 085r will be added to the next list update.

The Dynaco ST-80 and ST-120 are power amps and the list is just for integrated amps and receivers.

Have not heard of the receiver with the Queen Elizabeth picture. Would be interested in learning more about that one.
 
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GyroTuner said:
Thanks to everyone for their contributions. The sorted lists are nice.

The Quadraflex 085r will be added to the next list update.

The Dynaco ST-80 and ST-120 are power amps and the list is just for integrated amps and receivers.

Have not heard of the receiver with the Queen Elizabeth picture. Would be interested in learning more about that one.
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i have the sears version of this on my bench now, model 570.74100202

Annotation 2024-09-09 222300.png


3bx sa7100 sears 060.jpg

i'll get back to you on the output power.
 
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