General Forum

Re: Replacing the midranges on Penta (already done)

Turbo — Sat, 25 Apr 2009 06:48:07 GMT

After listening to the speakers for a while now, I have this conclussion: -I do not really know what I have acomplished

To be honest, the difference is not that big when listening to music with good sound quality. I have experienced greater improvements with the capacitor replacement, and changing the OP-amps in the amplifiers. However there seems to be a bigger difference when listening of lower quality of music, that is MP3 and such. The anoying mid range has become "softer" I find myself listening to the same tracks without being anoyed with the sharp penetrating guitars and other sounds in that frequency range.

I am quite sure that this is not due to the level of the elements being lower. When listening to very familiar tracks like Brothers in arms and some Ulf Lundell tracks it really sonds good and the voices and guitars sounds very good as they did before. So far the improvements are, as I said in the listening to MP3 oflower quality, and I really try to avoid these.

I will get back with some more findings!

Re: Replacing the midranges on Penta (already done)

Turbo — Sun, 19 Apr 2009 09:12:52 GMT

Very interesting discusion, by the way. Many issuses could be covered here, and I hope this could be to interest or use to the Penta owners.

So far, with no deeper analysis, it seems to be a very good modification. I have mostly been using the speakers for radio background listening and some playing while drunk Sounds as always very good for this, they are really impressive when played loud with a good quality CD.

I will do some more serious listening this week.

Re: Replacing the midranges on Penta (already done)

Turbo — Sun, 19 Apr 2009 09:00:33 GMT

I think I forgot to mention one thing about the installation of the new elements. The original way they are mounted can not be used with these elements. I used a simple solution, thick glue. Simular to silicone but made for making engine gaskets, it is black so it is not visible and the only problem could be if I want to change the elements again. This stuff is extremely strong and I guess that serious violence is needed if I want to replace the elemntes.

One thing that would be really interesting would be to compare this modification to new/old (but in nice condition) B&O-elements and refoamed elements. I am thinking of refoaming my old ones just for this. But it will always be so many issues to if I got it right and quality of the new foam etc, that this would not prove anything.

New elements would be more interesting, but it would be quite expensive to do this. If I knew anyone with Pentas it would be easier, but most of my friends think that I am an idiot putting money and time in to this. No one I know is interested in this and they think that their systems sounds perfect, systems they have bought from the supermarket or inherited from some relative...

Re: Replacing the midranges on Penta (already done)

rayfenwick — Sun, 19 Apr 2009 06:06:33 GMT

Dillen:

Ray, I 've been there, except I picked my nose rather than eat a bisquit.

Martin

Thanks for that Martin - it is the only way my electronics capabilities will ever be compared to yours

Re: Replacing the midranges on Penta (already done)

Dillen — Sun, 19 Apr 2009 02:07:05 GMT

Ray, I 've been there, except I picked my nose rather than eat a bisquit.

Martin

Re: Replacing the midranges on Penta (already done)

rayfenwick — Sat, 18 Apr 2009 17:27:05 GMT

You mean anything worth appreciating is worth suffering for - that kinda thing? No pain, no gain?

I actually like Marmite, but this stuff is nowhere near as tasty.... (as I found out when I ate a biscuit whilst having some un-noticed goo on my fingers.... )

Did I mention I *really* hate that stuff?

Re: Replacing the midranges on Penta (already done)

Medogsfat — Sat, 18 Apr 2009 14:27:28 GMT

rayfenwick:

Take apart tape deck. Stick fingers into previously un-noticed belt residue. Say naughty word. Walk to get stuff to clean hands, treading into the bit of sticky belt that dropped to the floor unseen. Don't notice you are now leaving sticky black marks on the wooden floor until it is too late. Say more naughty words. etc etc.

Some old belts go powdery, some stay pretty much the same. B&O ones (so far) turn into something like Marmite....

Ah! - but it wouldn't be as much fun or nearly as satisfying if it was easy Ray

I like the Marmite analogy though - you either love it or hate it!

Chris.

Re: Replacing the midranges on Penta (already done)

rayfenwick — Sat, 18 Apr 2009 11:08:57 GMT

Jandyt:

The causes of foamrot!
<snip>
My new theory is -----

-----lack of movement!

Well, constant movement would prevent stuff settling on the speaker, as the air would constantly be blowing it away. Plus the constant air movement would lead to pollutants being more diluted.

It is definitely true for drivebelts. Left static they stick to the drivetrain (small metal pulleys like motor pulleys first..) So I always advised customers to use cassette decks/turntables occasionally.

Someone I know had their Pioneer TT spinning constantly for well over a year. Not what I had in mind, but the drivebelt is fine....

Re: Replacing the midranges on Penta (already done)

rayfenwick — Sat, 18 Apr 2009 11:02:48 GMT

Dillen:

Gooey molten belt residue can be shifted fairly easily using IPA.
I agree, it can make the worst mess and is very hard to get off fingers and clothes.

Martin

Let me see if this sounds familiar to you Martin, though your workspace is most certainly more organised than mine...

Take apart tape deck. Stick fingers into previously un-noticed belt residue. Say naughty word. Walk to get stuff to clean hands, treading into the bit of sticky belt that dropped to the floor unseen. Don't notice you are now leaving sticky black marks on the wooden floor until it is too late. Say more naughty words. etc etc.

Some old belts go powdery, some stay pretty much the same. B&O ones (so far) turn into something like Marmite....

Re: Replacing the midranges on Penta (already done)

Dillen — Sat, 18 Apr 2009 10:39:59 GMT

Gooey molten belt residue can be shifted fairly easily using IPA.
I agree, it can make the worst mess and is very hard to get off fingers and clothes.

Martin

Re: Replacing the midranges on Penta (already done)

Jandyt — Sat, 18 Apr 2009 09:53:47 GMT

The causes of foamrot!
This has been discussed so many times, and always with no satisfactory answer.
Sunlight? I don't think so, as I have repaired Beo4s with rotten foam behind the display. Sunlight has never been there.
Tobacco? Don't think so, but may excaserbate (sp) the problem. I have seen remotes riddled with filthy brown nicotine, but still with good foam.
Humidity? Possibly.
Lack of humidity? Possibly.
Chemical reaction with air? Then why can one speaker be fine, and another goosed?
My new theory is -----

-----lack of movement!

I have a pair of Beolab Pentas that have been in use for 16 hours a day, since they were new in 1993. Perhaps switched off for around three weeks each year. That is a lot of hours (do the sum)!
One stands in a corner where the sun never reaches, the other has direct sunlight on it.
Neither is subjected to nicotine, as I smokes figs outside, or in the garage.
I have central heating.

All 8 midranges are like new. Not even tacky to the touch!

Andy T.

Re: Replacing the midranges on Penta (already done)

rayfenwick — Sat, 18 Apr 2009 09:27:52 GMT

Jandyt:

Yes, I too am following this thread with interest.
I have a pair of Beovox Pentas with midranges that are in the early stages of foamrot.

Of course you already know this Andy, but it gives me the chance to grumble anyway - don't ever touch the foam stuff! It is the nastiest, stickiest, most adhesive gunk known to man - like an excretion of the devil's bottom! (I went through a whole can of WD40 cleaning up behind that stuff when I refoamed a pair of CXs, and also belts on a 7700 cassette deck that had gone the same way...)

Now that's over with, I can ask if anyone else has noticed that speaker foams/belts in stuff that was in a smokey atmosphere seem to turn into that sticky tar-like mess far faster than stuff that has never been subjected to smoke? Must be some science behind this....

Re: Replacing the midranges on Penta (already done)

Jandyt — Sat, 18 Apr 2009 07:17:28 GMT

Yes, I too am following this thread with interest.
I have a pair of Beovox Pentas with midranges that are in the early stages of foamrot.

Andy T.

Re: Replacing the midranges on Penta (already done)

rayfenwick — Fri, 17 Apr 2009 18:51:36 GMT

Hi Jens

I think a few of us will be very interested in your results, and as you say, you can never tell with speakers, all strange things are possible

Re: Replacing the midranges on Penta (already done)

Turbo — Fri, 17 Apr 2009 18:50:08 GMT

cooldude:

Hi Turbo,

It's indeed very difficult to find matching drivers for B&O speakers. Especially if the original ones are no longer available (I don't know if the midranges drivers are still available by B&O but I think they prob are.)

I suggest , in order to get as good a sound as possible, to consider refoaming the original ones. I have refoamed many,many speakers now and the results are very satisfactory. If you can do it yourself (not that difficult, but a bit of a learning curve needed) it's a cheap solution that often gives very very good results and probably closest to original specs. The foam rings are available and cheap and the biggest factor is your time of cleanup and reglueing.

Anyways, I look forward reading your update in a couple of days.

I never really tried to find original replacements. Refoaming is one way to go, and I am for sure capable of doing it myself, but from the prices I have found on Ebay etc, it would be quite expensive.

I am not going that way because I am sure that the mid ranges on the Penats never were especially great from the beginning! No use on fixing something that could be replaced for something better. The original specs is not what I want, there are improvements to be done to this old construction. And to be honest even B&O cut corners in quality in components. Nothing proves that better than all the modification tips you can find here. Besides the agening of components that happends to all old electronics.

I could be wrong on choosing theese elements, but then i will let you now so no one else do the same misstake.