Advent 300 No Worky

Discussion in 'Solid State' started by Superman541, Aug 26, 2017.

  1. northpaw

    northpaw Active Member

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    210
    Location:
    New England
    On the Nichicon cap, odd that the datasheet does not fill the box for 4700/50 in its dimension matrix. You can ask digikey the question, or perhaps find the equivalent diodes you need from mouser if you want to order from the same place.
     
  2. Superman541

    Superman541 Active Member

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    127
    Thank you, Northpaw. It's folks like you who make me feel I can get good advice here.

    FWIW, I swapped out the Large Advents for a pair of Dahlquist DC-8s, and I was underwhelmed. The Large Advents rawk, in comparison. My humble view. I would like to get a pair of the fabled DC-10s, to experience.

    And for the record, just between us, SS gear does seem to my ear, to distort fairly quickly moving up from low volumes. VERY powerful SS gear does not do this as much, but I have a strong preference for tube gear, at all volumes. My humble opinion. So far as the systems I have heard. In my 60 years. It is my birthday today.
     
  3. Ballylongford

    Ballylongford AK Subscriber Subscriber

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    Happy birthday.
    :beerchug:
     
  4. northpaw

    northpaw Active Member

    Messages:
    210
    Location:
    New England
    Glad I could help out, and Happy Birthday.

    I had the Advent 300 paired with OLAs for at least 10 years (late 70s to late 80s), and they are a very good pairing. I'm not one for blasting, so I did not experience harshness with this setup. I've never had any tube gear, so I can't compare the relative virtues. Ditto for Dahlquist speakers, but there are some very strong proponents here for at least some Dahlquist models and I have no doubt that some of them are great performers.

    In the late 80s I went for more power with a NAD 7240PE in my main system. It was more powerful and while very good, I felt it was otherwise a lateral move from the Advent. More recently, I acquired a few Nak SR or TA series receivers, and feel they are a step up, but like the NAD, have a far larger chassis than the Advent. At any time I will have one of those Nak receivers paired to DCM-TF400s for a "second" system connected to a turntable, and a "main" system consisting of an Adcom GTP-450 and a Nak PA-5 paired to ADS L730s.

    Bottom line, I think it is hard to beat the Advent 300 for a small-form receiver. The only one that I've had that is competitive is a NAD 7225PE.
     
  5. Superman541

    Superman541 Active Member

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    127
    Yup, this thing does really well. I'm pretty sure it will be in service, somewhere in my house or garage, forever.

    I need to get an order in, for the filter caps and the diodes. I've been lazy, busy or both. Here is a simple question: Will this unit sound better with fresh filter caps, upgraded to 4700uf from 3000uf?
     
  6. Alan0354

    Alan0354 Super Member

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    2,679
    Location:
    Bay Area
    Questionable, but it's the right thing to do.

    I am hoping the diode will prevent the transistors from deep saturation and recover faster and hope you can hear the difference.
     
  7. sregor

    sregor AK Subscriber Subscriber

    Messages:
    3,190
    Location:
    Mass
    As Alan says, questionably, but the original caps weren't that great, and were mechanically a problem. Whether or not you change them, make sure the caps get securely tie-wrapped into position, as the leads breaking off the filter caps was another common problem. My 2 cents.
     
  8. northpaw

    northpaw Active Member

    Messages:
    210
    Location:
    New England
    Those two caps have to be replaced, they're leaking. If they are not affecting the sound yet, they will soon. They will loose their ability to effectively filter AC, and you will get more and more ripple on the DC rails. This will give you hum on the output, and expose other components to increasing AC where they are designed for fairly clean DC.

    That is why, back in post #8, I asked you to use your DMM to measure AC across the caps, as that is a measure of how much degradation has gone on. Now that you have sound, my guess is not much degradation yet, because you are not complaining about the sound. So I don't know if you would notice any improvement in sound with the replacement at this time (I did not when I changed my non-leaking ones), but sure as rain, the problem will come. Not replacing them would be sort of like leaving leaking batteries in your flashlight as you head out for a camping week because the light is still working...

    You can go with 3000µF or up to 4700µF; which one is not likely to affect the sound.

    Remember to pick up some desoldering braid, and one of those rosin flux pens (both available on the big river site, if not at digikey or mouser), as they will help you a lot with soldering.
     
  9. Superman541

    Superman541 Active Member

    Messages:
    127
    Thank you again, Alan, Northpaw and others who have been so kind. I have the 4700 uF, 50V caps that should work in the power supply. I intend to install them today.

    20171105_150610.jpg

    Alan, I also have the diodes you mentioned, though I am not sure I will try to install them today. Candidly, this receiver sounds amazing. Way more powerful that its rated 15W would suggest and one of the cleanest and warmest SS amps I have ever heard. There is no distortion problem to fix, it seems.

    I would like to get some input on another problem. This unit has two banks of speaker outputs. A and B. A works fine. The R side of B works fine. The L side of the B speaker output terminals appears to be non-working. I wonder what I could do/test, to see if I (we) can find the problem. There are two schematics, both very very tiny, attached to the bottom of the unit. The one below is a decent image of one of them (a .pdf I hope can be clipped onto this message). The other one is less clear. I find no "speaker" output mentions, or A/B speaker switch mentions, in either schematic. Is there anything you need from me in order to help determine the fault?

    Other Schematic.jpg
     

    Attached Files:

  10. northpaw

    northpaw Active Member

    Messages:
    210
    Location:
    New England
    The speaker switches (S6 and S7) are on the right side of the "better schematic", near the middle of the right side. The output jacks themselves are just labeled with large L and R. Everything comes into that final output area as a single feed, and the switches distribute the feed to the selected speakers and the headphone jack.

    If you have a problem with one of the B outputs, it is most probably in the switch for the B speakers, located behind the front panel. Try some cleaner/deoxit there and work it back and forth. There is little else that can go wrong, except a broken/corroded switch or broken/corroded wiring from that switch to the physical jacks on the back panel.
     
    stereoguy70 likes this.
  11. Superman541

    Superman541 Active Member

    Messages:
    127
    Thank you!
     
  12. Superman541

    Superman541 Active Member

    Messages:
    127
    Not the most professional job. The solders are not pretty, but they seem to be okay. Switches are deox'd. Hard to believe this thing will work after I fiddle with it, but we shall see.

    20171105_182713.jpg 20171105_182638.jpg
     
  13. Superman541

    Superman541 Active Member

    Messages:
    127
    It works! The Speaker B switch is finicky, it turns out.
     
  14. northpaw

    northpaw Active Member

    Messages:
    210
    Location:
    New England
    Finicky means the switch contacts are still dirty/oxidized. With no music playing, if you work it more (i.e., dozens of times) and hit it with small amounts of additional deoxit at times, it should continue to improve.
     

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