Evan’s MK2 BeoLab Pentas
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Wonderful thread Evan, congrats to a very nice work, looking good
The worst of the sealing issues I found was actually around the twee-mid baffle edge. The foam is predictably rotted and without any life left however that wasn’t the worst part. Whoever assembled this foam tape originally back in the day completely missed the actual sealing edge / contour of the baffle. This is effectively an acoustical “short circuit”.
Now its time to talk tweeters. As I mentioned earlier on, one of them was making zero output.
One of my eagle-eyed colleagues noticed that the lead wire was broken. The coil measured ok (from the broken end) so I decided to do a repair.
I attempted to solder the broken lead wire but unfortunately it is coated so nothing stuck to it. Next path was to take the butterfly off and take a turn off the coil and unwind some fresh lead wire. Sadly some more bad evidence of restaurant thrashing was hidden inside.
I think someone cooked this coil a little too hard! The coil was loose in the gap and had come off the former!
Wonderful thread Evan, congrats to a very nice work, looking good
Cheers, Soren! Thank you very much!
Ok so I’m officially up the creek with only one working tweeter at this point. Being the time-impoverished individual that I am, I leapt up from my workbench and into the car. Drove up to the office to rummage around for some tweeters that might hold me over until I replace the fried one with another original SEAS unit.
We seemed to be overstocked on these [very old build] H26TG06-06 units. These are almost completely unmatched in every way from the originals acoustically but they are an epic tweeter overall. I had to take the waveguide off of course and add some branding because stickers make everything better. Also had to glue down the butterfly as the clips that hold the waveguide on also secure the butterfly.
Last night was when everything came back together. I hauled them up stairs and plugged them in to the AVP. Just in time to watch an episode of our current series before falling asleep.
That glorious moment I have been working toward had finally come – time to flip the switch(es)!
The left BeoLab played sweet, sweet music but the BeoLab on the right was playing very loud 60Hz. Something is very horribly wrong. Sadly they will probably just sit for a while because I have been going hard on this project lately and as I pointed out earlier, those amps don’t make life easy. So unless I find another amp to run them on temporarily, it will likely be a while before this gets wrapped up. Wales is calling.
Luckily they are nice to look at. Thanks for reading and following along! If you happen to have a spare, functional amplifier I’d love to hear from you. Additionally if you have an extra Penta tweeter (SEAS 25 TNF H386) I’d love to take it off your hands.
This isn’t over, but over for now.
Small update for you folks. Yesterday I drove 250 miles round trip to pick up these bad boys:
This is a pair of MK2 BeoLab Penta amplifiers and I managed to also find them on FB Marketplace.
One of them is working fine but the other is blowing fuses apparently. In a little while I will go through and recap these just as I did the original pair. I’ll swap one of these (or whichever one is working) into the bad speaker and repair the original amp fully at a later date.
The cool thing about this project is once both of the naughty amplifiers are back in shape I will have a pair of spare amps to put to work! I think I will be 3D printing some accessory parts to make them look like BeoLab 200s.
I’ve always thought that it would be cool to “stack” two amps at the bottom and bi-amp the Pentas. I don’t think that they would sound much better, but I think they would look better being 15cm taller. 😉
Glitch
Ha! That’s a great idea! After writing my last post I realized I could build them as a tower of amps on a single plinth so that they form a “stereo” amplifier haha!
The system I am building is turning out to be very unique thanks to all these odd ingredients (which is something I’m beginning to appreciate!). It seems to be made of chess pieces! Almost nothing matches except for the Penta content.
I think for now I am going to stick with the BeoLab 200 plan once I sort out at least two, fully functional and refreshed amps.
With either the “stacked Penta” or “stacked BL200” you will need to figure out how to route the wires through the amps. The wire routing might be the most challenging part of the project.
I’m looking forward to seeing pictures of whatever you build.
Glitch
Hi Evan,
thank you very much for this thread! It will come in handy when I start to work on my Penta Amps tomorrow! By the way, did you measure the old filter caps after removal?
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