10-01-2015, 12:41 AM
Here is a couple videos of the issue.
First video is short but you can really hear the issue
https://www.youtube.com/watch?v=5O7y7qagKdw
It was very difficult to capture the cloth moving in and out but if you watch closely in the first video you can see it best around 00:32 until the end. It is far more drastic then the video captures, my wife even noticed immediately and that is saying a lot... LOL The buzz is quite clear and it is usually at certain lower frequencies. Again it sounds like a buzz, you should be able to hear it. Again, everything is tight, in place and installed correctly. I have went over the thing 100 times nothing is loose. I have also run the unit with the speaker out on the table and the speaker cloth removed and just the bare baffle and there is NO buzz under those conditions.
I deal mostly in `50s era hi-fi stuff and there are volumes upon volumes of books written just on speaker cabinet design> They discuss the importance of proper ports, air flow, internal size, how to tune the cabinet to certain frequencies, etc ect.
What I think is happening here is with this new fabric is far more restrictive about air flow then the original was, and thus it is causing the cabinet - baffle to resonate at certain frequencies where it did not before. As mentioned if I remove the grill cloth and run the radio with just the speaker and baffle it sounds wonderful and I can turn the volume full blast without any buzz or issue. The speaker is mint, no tears, no voice coil rub, no loose gasket, magnet or coil, but as I said it works perfect without that grill cloth installed.
I took a break from the Philco tonight and worked on re-capping a `57 RCA SHF-4 for a fellow down in Mexico. I am pondering some small shims between the speaker and baffle but leaving a small air port open to see if it cures the problem and will try that next tomorrow eve. Meanwhile if anyone has any ideas please let me know.
Thanks
Todd
P.S a Longer video playing a few channels but you can hear the issue on different channels and see how annoying it is. The bad thing is I really enjoyed listening to this little guy the last two weeks and now I can't stand it because of the constant buzz...
https://www.youtube.com/watch?v=KL_6SVn9OIw
First video is short but you can really hear the issue
https://www.youtube.com/watch?v=5O7y7qagKdw
It was very difficult to capture the cloth moving in and out but if you watch closely in the first video you can see it best around 00:32 until the end. It is far more drastic then the video captures, my wife even noticed immediately and that is saying a lot... LOL The buzz is quite clear and it is usually at certain lower frequencies. Again it sounds like a buzz, you should be able to hear it. Again, everything is tight, in place and installed correctly. I have went over the thing 100 times nothing is loose. I have also run the unit with the speaker out on the table and the speaker cloth removed and just the bare baffle and there is NO buzz under those conditions.
I deal mostly in `50s era hi-fi stuff and there are volumes upon volumes of books written just on speaker cabinet design> They discuss the importance of proper ports, air flow, internal size, how to tune the cabinet to certain frequencies, etc ect.
What I think is happening here is with this new fabric is far more restrictive about air flow then the original was, and thus it is causing the cabinet - baffle to resonate at certain frequencies where it did not before. As mentioned if I remove the grill cloth and run the radio with just the speaker and baffle it sounds wonderful and I can turn the volume full blast without any buzz or issue. The speaker is mint, no tears, no voice coil rub, no loose gasket, magnet or coil, but as I said it works perfect without that grill cloth installed.
I took a break from the Philco tonight and worked on re-capping a `57 RCA SHF-4 for a fellow down in Mexico. I am pondering some small shims between the speaker and baffle but leaving a small air port open to see if it cures the problem and will try that next tomorrow eve. Meanwhile if anyone has any ideas please let me know.
Thanks
Todd
P.S a Longer video playing a few channels but you can hear the issue on different channels and see how annoying it is. The bad thing is I really enjoyed listening to this little guy the last two weeks and now I can't stand it because of the constant buzz...
https://www.youtube.com/watch?v=KL_6SVn9OIw
