Second hand display's are few and far between. They can be ordered at B&O, but it'll cost you. I've never worked with the Ridax display's, so I can't comment on them, nor on how easy or hard it is to fit them into the Penta's. Regarding your other steps in upgrading the Penta's, I've got a very different opninion then that of the topic starter.

Directly soldering the wiring to the unit with silver soldering, will not give you any audible inprovement. It is stated that the resistance of the connectors is very high, and that of silver solder is very low. This is true in a way, but the differences are to small to be heard. Fact of the matter is, that altering the resistance does in no way alter the soundquality. The resistance of the connectors is absolutly lineair in the audiospectrum, just as the silver solder is. The only influence a lower resistance has, is that he speaker will play measurably louder then the connector version at a given input signal when using silver solder. But the difference is very small and can easily be corrected by turning the volume up a very tiny amount. The only thing you will accomplish, is that the resoldered Penta unit is just a minute tad more sensitive then the connector version. But given the fact that Penta's are a relativly sensitive speaker already, you gain no substantial benefit. This we tested in many different ABX hearing sessions at my former company. But that is just my 2 cents.

Adding or replacing your amplifier will also not give you much improvement. It is often stated that the Penta's need a very beefy amplifier to really shine. I've got no idea who started that statement, but it is ridicilous. The Penta's are very sensitive for a cone-speaker system (91 dB versus 86-88dB for an average speaker), so no need for power in that respect. The impedance curve is also very amplifier friendly, so no need for power there either. I drive a set of Penta's using a 12 Watt OTL Tube amplifier at home, and this combo can play loud enough to make windows rattle. Ok, the Penta's are capable of earthshaking volumes, if you drive them with a 200 Watt per channel amplifier, but I doubt one will ever reach those volumes in normal live in there home setup.

But hey, those are just my 2 cents on those matters. I am a trained electrotechnician, so I normally use to smile when audiophiles claim outragous improvements, which have no electronical or physical explanation what so ever. I just want to let you in on the other side of the coin so to speak. Believe who you want to believe, and make your own discissions.

Good luck with your modding project. Hope it works out for you!

Chasepoes wrote:

Yes this feeds directly to the display. Behind the plastic front (inbetween the two front grills) you'll find the other end, with a connector attached. If you can find the original LCD display's, you can connect them directly to that connector and mount them behind the translucent front. Plug the bottom connector directly in a powerlink and the display's will work. No soldering or external AC required!

How did/would you do that?

All the penta display's get there power (10V AC, type mkI, II, III) through the powerlink, which comes from the main transformer.  

Imho a wrong suggestion.

Beobuddy wrote:

How did/would you do that?

All the penta display's get there power (10V AC, type mkI, II, III) through the powerlink, which comes from the main transformer.  

Imho a wrong suggestion.

What I meant was: If you connect the original display's to the connector found behind the plastic panel (situated inbetween the two front grills), the display is connected correctly. Offcourse you have to hook the Penta up with a Beolink capable amplifier, using a Beolink cable for them to work. There is no need to 'change', rewire or solder anything inside the Penta to make it work, that was my point.

The idle current trimmers go bad and the idle current can run astray, that's a common fault.
Seeing Penta amplifiers melted down, like the one pictured, is not common.
The "melted" plastic in the penta amplifier is just a sign of an ignorant or unaware owner, who let the amplifier
run even if it started to hum (which BTW was noted by the owner) got red hot and presumably started to smell of burning
dust and warm electronics in either order.

Regarding refoam'ing, I am not worrying too much about the spider alignment - the cone is not too heavy in
these speakers so not very prone to distort the spider - but rather the coil/pole piece.
You may be able to center everything correctly without shim'ing anything, you also tell that you have a huge
experience which presumably lifts your success rate but trust me when I say that far from
all owners can do the same.
I have lost count of the failed DIY-jobs arriving here. Something either "didn't quite fit" or "didn't
quite come out as planned" or the speakers "for some reason" started to distort after a DIY refoam.
Some owners stop when they realise that they are in too deep and while things can still be saved - others don't.

I agree on the connectors. They are not as bad as some people might think and I also doubt that soldering the
connections will improve the sound quality. Indeed the change in resistance would be microscopic and the introduction of
a small resistance will not affect sound quality - only volume - and unless a connector is really bad, lose or burned, you won't
ever notice any difference.
The connectors solder joints in the board is a different matter though. They can crack and that can indeed
cause sound problems so they should definitely be attended and solder with a hint of silver would be what
I would choose too since it doesn't tend to crack as easy as the standard 60/40 or 63/37.

The Pentas are wonderful speakers and they are worth restoring.
The capacitors in the crossovers are important for sound quality and they will have started to dry out by now.
The same goes for the capacitors in the amplifier section of the Beolab versions. Here the problem is not specifically sound
quality related but rather a matter of stability. Important none-the-less.
There is, however, a few capacitors in the signal path that needs attention and also a couple of op-amps that can be replaced
with better modern types as also suggested by Die_Bogener in another Beoworld thread.
A convenient kit is available, put together with Die_Bogeners friendly assistance and partly
based on his superb suggestions. Improvements you can actually hear.
The Penta amplifiers are some of the better discrete amps built by B&O. They are not as bad as some owners
think - they just need the usual 20+ year service like any other electronic item.

Martin

Hi & thanks for the very valuable comments & suggestions , which adds even more confusion & hesitation about what to do, but at least gives a better idea of what can change (or not) if one replaces something by something else. 🙂

I guess my only urgency at the moment is the midrange drivers being rotten, after that I'll be able to do proper listening sessions & find out if something else needs to be improved.🤔

Chasepoes wrote:

Directly soldering the wiring to the unit with silver soldering, will not give you any audible inprovement. It is stated that the resistance of the connectors is very high, and that of silver solder is very low. This is true in a way, but the differences are to small to be heard. Fact of the matter is, that altering the resistance does in no way alter the soundquality. The resistance of the connectors is absolutly lineair in the audiospectrum, just as the silver solder is.

Sure, but the resistance between different connectors is not constant. I'm not claiming that would be audible either, measurable just perhaps...

Adding or replacing your amplifier will also not give you much improvement. It is often stated that the Penta's need a very beefy amplifier to really shine. I've got no idea who started that statement, but it is ridicilous. The Penta's are very sensitive for a cone-speaker system (91 dB versus 86-88dB for an average speaker), so no need for power in that respect. The impedance curve is also very amplifier friendly, so no need for power there either.

Just what I have been saying... Pentas are excellent speakers for silent listening. No need to make them jump before the music "opens up". Hooking them up to a Beomaster 900 was very enlightening.

In another post:

What I meant was: If you connect the original display's to the connector found behind the plastic panel (situated inbetween the two front grills), the display is connected correctly. Offcourse you have to hook the Penta up with a Beolink capable amplifier, using a Beolink cable for them to work. There is no need to 'change', rewire or solder anything inside the Penta to make it work, that was my point.

But the Penta displays need power to work. It will not come over Powerlink, you have to supply it from somewhere else if the Penta amp is left out of the equation. So not quite as simple as "hooking them up".

tournedos wrote:

resistance between different connectors is not constant. I'm not claiming that would be audible either, measurable just perhaps...

Ok. I thought the soldering was done to improve the sound. Simply disconnecting and reconnecting them again will make them have perfect contact again.

tournedos wrote:

But the Penta displays need power to work. It will not come over Powerlink, you have to supply it from somewhere else if the Penta amp is left out of the equation. So not quite as simple as "hooking them up".

Your right. I just thought that the previous poster intended to mount some Beolab 200's. The auxilary power is not necessary in that setup.

Hi, I've just received the new rubber rings by mail today, so tomorrow being a bank holiday in France, I'll start refoaming the midrange drivers and hopefully at the end of the day I'll discover a better "Penta sound"😁

Well, I've just completed refoaming one of the Pentas, didn't expect it to be so easy, once you know what to do and where to glue, it's like making pancakes, only the first one is a mess, then the others are great!

The sound improvement is obviously noticeable, now I'm going to silver solder the filter wires and keep working on these beauties..Just finished cleaning the frets as well, now they start looking great!😐

Someone in the first messages on this post showed pictures of the "original" Nokia midrange drivers, and guess what? Mine are not Nokias! 

They were made by a German company called SEL, I couldn't find any info about them on the net..see for yourself:

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