General Forum

Re: Some questions about pentas and crossovers

tournedos — Mon, 28 Dec 2009 15:31:33 GMT

Foams - you can't get them from B&O, only complete new midrange drivers. Not that expensive, but needing eight of them still makes it an investment.

No problem at all mixing caps from different manufacturers (or even different types). I got all the caps for mine by Intertechnik (160V MKT). The 27 uF is a bit of an oddball, but IT makes it as well - I had to wait a long time for my order because of them though. You might just as well use 22 + 4.7 uF in parallel which will be close enough and much easier to source. Likewise 8 or 8.2 uF is pretty much the same, differences this small will disappear in the tolerances of real components.

The original caps were nothing fancy, just regular bipolar electrolytics. When new, they will sound just fine, will be a lot cheaper than foil caps, and will physically fit in place without modifications (the 68 uF MKT caps will not). There are a couple of caps on the crossovers that are plastic foil types to begin with (the white, square ones) - leave them be, they will not suffer from age and replacing them won't do much good. You'll obviously need to replace defective parts though, sounds like you may have a problem there.

Re: Some questions about pentas and crossovers

Steven Aston — Thu, 24 Dec 2009 14:12:57 GMT

Sorry, They are Beolab Penta, MKII. 1992. Getting signal from a beomaster 4500 and Beovision 3-32.

Re: Some questions about pentas and crossovers

Premiumverum — Thu, 24 Dec 2009 13:22:26 GMT

Are they beovox or beolab penta's? (without or with the built in amplifier)

Changing the electrolytic caps is always a good idea in speakers this age. Beoworld member Dillen can probably supply a kit with all the right capacitors you need! Drop him a PM.

Good luck with your penta's!

Some questions about pentas and crossovers

Steven Aston — Thu, 24 Dec 2009 12:47:09 GMT

Hi all, first time posting on the forum. Been lurking in the background awhile now. I have just acquired a set of penta II's and they need some work.

First off, they need midrange foam as usual. I have found a kit on the bay for 42, has anyone ever tried this? is it worth it? or should i get OE foam from B&O?

Secondly, Only the center midrange drivers are working, opened up the speaker and tested the drivers. They seem to be working just fine, there is no signal on the blue connection on the crossover. Any ideas?? I checked all the caps, the 22MFD cap seems to be open and the 68MFD cap only has a capacity of 1.7MFD. Could this be casuing the problems?? according to the schematics i found, its a straight shot from the - conection to the blue wire. if the cap is shot I should just be getting full signal right??

Thirdly, I have read all of the posts on penta upgrades from caps to silver soldering all of the internal connections and ICE power. I am located in the us and I cannot find all cap sizes i need from a single brand or model, can i mix and match caps from different brands and lineups??How will this affect the sound?? Or can i go with a slightly larger or smaller cap so that I can go with the same brand all around? for example using an 8MFD instead of an 8.2MFD or a 25 instead of a 27?? Which scenario is better? Unless someone can tell me where I can get all needed sizes from one brand and supplier. I require the following:

x8 .68MFD

x2 5.6MFD

x4 8.2MFD

x2 22MFD

x2 27MFD

X6 68MFD

Which brand is recommended?? read alot about the mundorf caps but thats a lot more than I can spend at the moment. What brand would give me OE sound?? Just want to get them running correctly at this point in time. I can always go back later and upgrade to better caps once I have everything working and the ICE conversion done.

Sorry for all of the questions, I really hope that someone here can point me in the right direction. Would love to get my speakers up and running. THANKS!!!