Update. I have all 17 100uF caps now fitted with Panasonic FR 35V types (with the change of polarity of C16/C17) and I couldn't be happier.
https://www.mouser.de/ProductDetail/Panasonic/EEU-FR1V101?qs=tfZGHB2PWd1LosiJY3G7%2Bg==&countrycode=DE¤cycode=EUR
I did not bridge some of the capacitors. The sound is rich balanced full and very spatial. Also, the frequency response is very balanced.
I had in between increased the output voltage and I had to exchange the last 2 resistors in the signal path of each channel before the output. This was disappointing and I went back to the standard 0.5V with 2.2K in series and 1K in parallel. Unfortunately the legs of the original resistors were broken off when I bent them again. I thought it would be no problem to change them. First I had Vishay metal film resistors. The sound was aggressive. Then I followed a recommendation from a forum (not for the 34) and took KOA SPR 2 watt. The sound was very clean and pleasant but all the spaciousness was gone, even after two weeks of listening. But I had also ordered the same types in the 1 watt version. I can not believe it but all the spaciousness was back. The 2 W types sound a tad "cleaner" but I quickly got used to this bit more distortion of the 1 W type. The musicality and 3D presentation are more important to me.
So the 34 can stay to my satisfaction.
I do not belong to the group of esoterics. I have also not exchanged the parts for reasons of a curiosity. The caps were too old and the resistors broke in two. Maybe someone can explain scientifically why the 2 watt types sound so sterile and 2D but the 1 watt caps of the same series KOA SPR so open transparent and musical. I'm not counting beans, it's obvious to the ears of my wife and our friends as well.
BTW for all lovers of the Quad 306, I have found at Mouser inexpensive and good banana speaker plugs that do not change the outer appearance but much more stable to accommodate the plug because they are made of gold-plated metal and not a thin sheet metal sleeve in a plastic tube.
https://www.mouser.de/ProductDetail/Pomona-Electronics/2854-2?qs=4luskHXVU9Y30tZjyXNdvg==&countrycode=DE¤cycode=EUR
As a replacement for the mains electrolytic capacitors of the 306 I installed these new caps. They last 8000 hrs at 105 degrees and they sound very good (if they are allowed to have a sound at all).
https://eu.mouser.com/ProductDetail/KEMET/ALC80A562CC063?qs=T94vaHKWudSbqp8mWLAllw==&countrycode=DE¤cycode=EUR
https://www.mouser.de/ProductDetail/Panasonic/EEU-FR1V101?qs=tfZGHB2PWd1LosiJY3G7%2Bg==&countrycode=DE¤cycode=EUR
I did not bridge some of the capacitors. The sound is rich balanced full and very spatial. Also, the frequency response is very balanced.
I had in between increased the output voltage and I had to exchange the last 2 resistors in the signal path of each channel before the output. This was disappointing and I went back to the standard 0.5V with 2.2K in series and 1K in parallel. Unfortunately the legs of the original resistors were broken off when I bent them again. I thought it would be no problem to change them. First I had Vishay metal film resistors. The sound was aggressive. Then I followed a recommendation from a forum (not for the 34) and took KOA SPR 2 watt. The sound was very clean and pleasant but all the spaciousness was gone, even after two weeks of listening. But I had also ordered the same types in the 1 watt version. I can not believe it but all the spaciousness was back. The 2 W types sound a tad "cleaner" but I quickly got used to this bit more distortion of the 1 W type. The musicality and 3D presentation are more important to me.
So the 34 can stay to my satisfaction.
I do not belong to the group of esoterics. I have also not exchanged the parts for reasons of a curiosity. The caps were too old and the resistors broke in two. Maybe someone can explain scientifically why the 2 watt types sound so sterile and 2D but the 1 watt caps of the same series KOA SPR so open transparent and musical. I'm not counting beans, it's obvious to the ears of my wife and our friends as well.
BTW for all lovers of the Quad 306, I have found at Mouser inexpensive and good banana speaker plugs that do not change the outer appearance but much more stable to accommodate the plug because they are made of gold-plated metal and not a thin sheet metal sleeve in a plastic tube.
https://www.mouser.de/ProductDetail/Pomona-Electronics/2854-2?qs=4luskHXVU9Y30tZjyXNdvg==&countrycode=DE¤cycode=EUR
As a replacement for the mains electrolytic capacitors of the 306 I installed these new caps. They last 8000 hrs at 105 degrees and they sound very good (if they are allowed to have a sound at all).
https://eu.mouser.com/ProductDetail/KEMET/ALC80A562CC063?qs=T94vaHKWudSbqp8mWLAllw==&countrycode=DE¤cycode=EUR
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