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  1. #1
    Senior Member mark214's Avatar
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    Question Crown DC-300A & D60 service

    I have pair of DC-300A and a D60 amps that have been sitting unused for 10+ years, I am looking to have checked/serviced.
    Any recommended techs out there?
    Thanks
    Last edited by mark214; 10-28-2021 at 12:39 PM. Reason: correction

  2. #2
    Heather [Senorita member] hjames's Avatar
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    Quote Originally Posted by mark214 View Post
    I have pair of DC-300A and a D60 amps that have been sitting unused for 10+ years, I am looking to have checked/serviced.
    Any recommended techs out there?
    Thanks
    I see your location is "Low Earth obit" but perhaps if we knew better where you are actually located we could offer more helpful info.
    I've had good luck with Music Technology in Springfield, VA - but no idea if that's local to you or not.

    https://www.musictechnology.com/
    2ch: RPi-4, Oppo, Acurus RL-11,Jolida 502,Valencias,JBL L212,Von Schw
    7: Oppo BDP103D, B&K, UREI 809A, JBL B460

  3. #3
    Dang. Amateur speakerdave's Avatar
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    There's an outfit in Crown's home city that specializes in legacy Crown products.

    AE Techron, Elkhart, Indiana.
    "Audio is filled with dangerous amateurs." --- Tim de Paravicini

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    Quote Originally Posted by speakerdave View Post
    There's an outfit in Crown's home city that specializes in legacy Crown products.

    AE Techron, Elkhart, Indiana.
    AE Techron was the industrial amp division of Crown, some of the original Crown audio techs also work there
    now.

  5. #5
    Senior Member mark214's Avatar
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    I hooked up the first DC300a to a pair of speakers and looped it off of an iPod for 12 hours a day it ran well, without a fan the heat sinks were warm but not hot the pots were noisy as heck but a blast of DeoxIT ended that issue.
    The other DC300a will be run through the same thing.
    The caps look original, I am going to look at having them replaced, neither amp looks like they have been serviced.

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by mark214 View Post
    The caps look original, I am going to look at having them replaced, neither amp looks like they have been serviced.
    Are these the original series A, not the DC300A-II? Either way, one tough amp that may still be performing perfectly. Though not saying you shouldn't have it checked out. The years fly by but my original D150 went back to Crown sometime around 1977 when it was still in warranty and has been soldiering on just fine ever since.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Do both channels of the amps sound the same?

    Keep in mind the DC (direct coupled) 300 has no coupling caps in the signal path, not saying there could
    be a few other small electrolytics that maybe could be needing changed.

    Remember that direct coupled means that amp will pass and amplify DC voltage if there is any on the input!

    The D60 amps do have coupling caps in the signal path.

  8. #8
    Senior Member mark214's Avatar
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    Quote Originally Posted by Mike Caldwell View Post
    Do both channels of the amps sound the same?

    Keep in mind the DC (direct coupled) 300 has no coupling caps in the signal path, not saying there could
    be a few other small electrolytics that maybe could be needing changed.

    Remember that direct coupled means that amp will pass and amplify DC voltage if there is any on the input!

    The D60 amps do have coupling caps in the signal path.
    Are there any way or ways to protect speakers from the potential of passing DC from a DC 300a? Or is that not a major concern with the direct coupled amps?
    Yes both channels sound about the same.
    Protecting at best hard to replace JBL speaker components is a primary consideration.

    Thanks to You and all who have posted to this thread, if has been very helpful.
    Last edited by mark214; 10-31-2021 at 06:00 PM. Reason: added comment

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    For use when driving compression drivers its standard procedure to install DC blocking capacitors in the speaker enclosure for just that purpose usually sized to roll off about two octaves below the desired crossover frequency. Not terribly practical for speakers with crossovers below a few hundred Hz. Its a big part of the reason that DC300s went out of favor with professional users back in the 80s. It's not out of the question to build an outboard relay protection circuit to emulate that used in most large power amps but I don't know of any off the shelf versions these days.


    Quote Originally Posted by mark214 View Post
    Are there any way or ways to protect speakers from the potential of passing DC from a DC 300a? Or is that not a major concern with the direct coupled amps?
    Yes both channels sound about the same.
    Protecting at best hard to replace JBL speaker components is a primary consideration.

    Thanks to You and all who have posted to this thread, if has been very helpful.

  10. #10
    Senior Member mark214's Avatar
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    Quote Originally Posted by BMWCCA View Post
    Are these the original series A, not the DC300A-II? Either way, one tough amp that may still be performing perfectly. Though not saying you shouldn't have it checked out. The years fly by but my original D150 went back to Crown sometime around 1977 when it was still in warranty and has been soldiering on just fine ever since.
    Mine are the pre series II amps.

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    Senior Member mark214's Avatar
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    Thanks again for the responses.

    I found a service center that has been servicing Crown JBL and many other lines of pro gear for many years about 100 miles from me and will be working with them directly.

    The post on Velleman protection gear or for that matter any other manufactures of devices that will protect my valued JBL speakers looks like something I will be looking into as well.

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    I still use blocking caps on HF drivers and the days of powering them with DC300's are long over.

    If I'm not mistaken the Crown manual had a schematic for a relay DC protection circuit to put between the amp and speaker.


    Edit......I just looked up a DC300 manual and the relay circuit was for general overload protection where the a relay would switch a light bulb in series between the amp and speaker. It would most likely help save your speakers for a DC accident.

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    Quote Originally Posted by mark214 View Post
    Thanks again for the responses.

    I found a service center that has been servicing Crown JBL and many other lines of pro gear for many years about 100 miles from me and will be working with them directly.

    The post on Velleman protection gear or for that matter any other manufactures of devices that will protect my valued JBL speakers looks like something I will be looking into as well.
    Hello!

    I wonder if you would share/recommend the service center you referred to in the quote?

    I have some vintage Crowns - PSA2, SA2, DC300s that need some attention

    Thanks for your time!

    Rob M.

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by dvr3725 View Post
    Hello!

    I wonder if you would share/recommend the service center you referred to in the quote?

    I have some vintage Crowns - PSA2, SA2, DC300s that need some attention

    Thanks for your time!
    If you read the entire thread you will see a helpful suggestion for Crown service from folks who will actually respond when you ask them where they are!!

    These guys know Crown better than anyone else left out there: https://crownservice.aetechron.com/
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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