Penta High End-  a great projekt.

 

What to do:

Change broken midrange speakers, remove the useless and sound destroying "push on" terminals and make silver soldering, and maybee make outside speaker connektion for use with a new extern amplifier

In this tread;  olso how to change tweeter to a modern type and much more

 

 

 

Typical problem on all kind of Penta´s, -  new or old old - BeoVox or BeoLab -The midrange are broken

 

How to remove grill. Place two fingers on the cloth  precisely where you can feel the clips, and then pull out  the cloth , - then the lock release 

 

Place the speaker on a table, and remove the grill  (Remember to PROTECT THE CABINET against scratches!)

 

 

 

Change the midrange drivers and cut off the push-on terminals and make a real silver soldering instead (use WBT-0820). The connectors are made of some kind of cheap metal and not cobber!, (but they are easy to mount on a factory!) 

 

They have a huge resistance and therefore not make the sound optimal. Remove them all.

 

 

Adjust the hook to the speakers if necessary.

 

 

 Then do the same on  the push-on terminals of on the bas and tweeter and make a soldering. For best result use silver soldering (WBT 0820) be carefull with the tweeter and dont use to much heat to long. Remember to PROTECT THE CABINET against scratches. the bass speakers can easely touch the sites of Penta

 

 

Use strips for protect lose wiring. If not, you will here them make noise when you play loud.

 

 

When finish with the soldering, replace the speakers again

 

 

 

 Go to filter in button- now its getting a littel more difficult. Its possible to remove the print for getting more space if you like. A good idea is always to take lot of pictures, before you lost the tread..

 

 

Cut off all push- on terminals again and make real soldering .Notice that the wires to print is very short.

 

Now its sunday...

 

If you want to use and another amplifier then change the speaker main wire to a longer one (you need 2 x 1 meter HI- END speaker cable - find a good thin type or drill a bigger hole in print). For best result, soldering the main speaker cable direct to the print.

 

 

The speakers wires inside the cabinet are made of pure cobber and sound absolutely okay . Once I have tried to change it to HIFI Supra speaker cable, but without any special improvenment. Therefore I canot see there are no need to change the original cables.

 

The new main speakerwire is drop down inside the old - now un-used amplifier, and coming out somewhere in of the buttom. Find the way you like best.  Make then holes for new speaker terminal underneath, use the best speakers terminals you can find  (yes I know, they are very expensive, but you can hear it!

 

IMPORTANT Remember to remove the main fuse in button of the amplifier and only leive the small fuse for the display,- it shall still work as normal.

 

Then its monday again..

 

 

That is a really good job Erik!
Thankyou for sharing this, and taking the time to do the excellent photo's!

Andy T.

Hi,
 

Very nice project.  I think if you combine this with the modification of the condensators, suggested by Die Bogener on the old forum, this should be even more impressing!

PS 1: what kind of Icepower amplifier do you use?

PS 2: any tips on removing the cover of the penta, without risking to damage the display? 

kind regards

Joost
 

Excellent job done. But why not an upgrade to the filter.

Just change the caps to polypropylene Audyn cap plus or better, and bridge them with a small 0.01µf cap to make the sound even smoother.

 Thanks  to all,  I`m glad to show my projekt for all in BeoWorld. Its not only the ear that can hear the changes. Here are the visible result  of the projekt

First I have powerede my 4  Penta with 4 X 1000ASP ,- and then the B&W,-PV1 subwoofer have 500 watt ICEpower . My next projekt are to power the Avant (center)speakers with 1 X 250 watt ICEpower

 Here are the amplifier I use for the front Penta, the rear amplifier are the same inside  but in a onother cabinet.

Penta, BC2 , B&W- pv1 and BeoVision Avant

 

 

 

 I have change the condensator in some others Penta before, but its ekspensive, ( 100- 200 euro each ) therefore i wait with this projekt . I have four Penta !

I have make some notes from the old projekt, and I hope BeoWorld members  will use them

 WHY USE TIME FOR THIS PROJEKT ?

Condensator need to bee change after  while. Here are a picture of a old (open) condensator. It should have been covered by silver , but now there only are a litle in the end.

 

 

Typical condensator

 

 

BeoLab /BeoVox NORMAL FILTER diagram

 

Here is a diagram if you instead want to make biwiring.

 

This graf shows the difference betveen a old and new condensator!

 

Condensatorer in filtrene , to one Penta  speaker (all types ),  are named here

Notice: uF is called "Micro Farrad" and nF is  called "NanoFarrad"

Midrange filter

C1: 22 uF 10% 35 V 

C2: 8,2 uF 10% 35 V

C3: 82 uF 15% 35 V

C4: 3,3 uF 10% 100 V

C5: 10 uF 10% 35 V

C6: 680 nF 10% 63 V -  olso called 0,68 uF

C7: 680 nF 10% 63 V -  olso called 0,68 uF

C8: 22 uF 10% 35 V

Bas and tweeter filter

C1: 68 uF 10% 35 V

C2: 220 uF 20% 35 V

C3: 47 uF 10 % 35 V

C4: 2,2 uF 10% 100 V   (tweeter)

C5: 3,9 uF 10% 100 V   (tweeter)

C6: 680 nF 10% 63 V - is a 0,68 uF   (tweeter)

Always use the best condensators  for tweeter and midrange. Its okay to use different brand in same filter, but keep them together.

 which mean one brand for tweeter and another brand for midrange.

 

If you not have time or money to change them all, then  first change condensator that are placed in serie, becouse they are most importent for the sound.

Most used brands in Hi-End condensators are these:

(choose MKP or MKT types) and yes- they are expensive,  but popular for DIY

 

Audyn CAP from Intertechnik,         Mundorf      J E N S E N

                             http://www.lautsprechershop.de/english/index_hifi.htm 

  

Notice .

If you have one of the first Penta,MK1 and MK2 you also need to change one speciel  resistance called  R1 in the midrange filter.  (See diagram)

It will give you a tiny difference in clear an natural midrange.

 If is a  3.3 ohm (colourcode: Orange, Orange, Black) you shall change it to a  to a smaller one; 2,2  ohm (Colour code: Red, Red, Black) 

 BeoLab with green display (MK3) should proberly already have this modicifation (Mk1 and MK2 with Yellow and Orange display have not).

All BeoVox Penta olso need a check, You can`t see which  version it is outside!

 

Very nice project, and thank you for sharing it with us!

I have one comment:

Penta2 seems to exixt with both versions of filters. I have Penta2 with the 2,2ohm resistor and other components identical to your diagram.  

I discovered that the versions with filters with 3,3ohm resistors has different capacitors and coils also, worth looking in to before ordering parts. This circuit diagram is in the work shop manual for Beolab Penta type 6621, 6622, 6623, 6624, 6625.

My Pentas are type 6621, which is confusing, should that not mean that they are an early version, why would they have the "newer" filters? 

The different type numbers are often just for different regions if listed for the same model and only the last digit changes.

 

 Here are  how a 20 years old  Penta amplifier look like inside!  Its nearly exploding!! The first sign are humming...

hi Bulgarien,

 

could you please tell me if the midrange drivers were ordered directly from B&O? If yes,I would like to know the caracteristics if possible( Brand name and if is 4OHM or 8OHM?).

 

 I would appreciate if you can provide me that information! (I bought Penta 1 speakers few weeks ago and all the drivers were replaced but not with the originals one so your help will help pe for sure!)

 

regards,

constantine

You ordre the midrange drivers at your normal B&O shop.

Dont worry if the labelname are different from the original.

 The label name on the old one was Nokia!, now its no-name  but its the same speaker with the same spec as the "original") If its fits, there is no problem.(you will proberly only  need to adjust the "hook "

You can see the name Nokia on the two old  midrange speakers to the left, the others midrange on right site  are new ones

Hi Bulgarien,

Thanks for all the pictures! Really nice.

 

Do you really think that soldering all the connections is well worth the hassle?

It is a lot of work disassembling the speakers, and I am afraid that I'm going to dent or scratch them in the process! I have replaced all the capacitors in both the crossovers and the amp, and I think the speakers sound really good as they are now. However, everything can be better!

What do you think? Should I go through with this as well?

 

Magnus 

Do you really think that soldering all the connections is well worth the hassle?

 Yes no doubt about that, its not difficult , its take some hour and yes it´s so boring, but you have to understand that the very fine signal to the speakers will see all kind  of connectors as a resistor.

 

Only with a silver soldering the original, full and clean signal will

 

There is no easy way to High End sound, but I will promise that you can  hear the difference.

Thanks. I wasn't trying to criticize you in any way, I just wanted to make sure that this was really worth it before trying to pull the grilles of again. Nearly destroyed them before giving up the last time! :p

Great project! I am very impressed!

Thanks for sharing 

 If I can convince  you and others about the great Penta sound you can get on easy  and cheap way, then I´m happy

How to remove the  Penta grill, without breaking anything.

Place two fingers on the cloth  precisely where you can feel the clips, and then pull out in the cloth (one or two centimetre), - then the key release  and the grilles suddenly  jump out.

Do the same one the others clips. I think there are 8 at the top and 8 at the lowest grill

When put it on again, just click it on, step by step.

Job done!

 

Hi there, I am new to this and have got a pair of these and limited knowledge.

I understand most of what has been done but if someone could please advise me. Assuming the rest of the speakers are in good order can the amplifiers be removed and then plug into the red and black terminals shown in the pictures. (these are the ones the amplifier output connects to) with another amp rated 8 ohms 150w. My thought is to use the speakers and casing but drive them with a high end home theater receiver using its internal amp instead of the Penta Amps.

Yes - but you might want a pair of Beovox Pentas (without amplifier) rather than the Beolab ones!

Brian

amazing!

saw this project before and the first thing I thought was "respect"

Thanks  I´m glad that I can help.

The schematic shows all four bass drivers installed in series, which would mean they are 32ohm each???

Bulgarien:

 

 Here are  how a 20 years old  Penta amplifier look like inside!  Its nearly exploding!! The first sign are humming...

What about the amplifiers in the beolab 6000 - 8000.

Will they have the same problems after 15 - 20 years??

The schematic actually shows them in parallel.  I believe they are 8 Ohm units, but I'm not sure about that

I have a Beomaster 8000 that could be a good partner with my Beovox Penta's, but the BM8000 can only provide 150w if the total cumulatative load is 4 ohm, so I could use a pair of 8 ohm units in parallel to get 4 ohm, or possibly other combinations wired up in serial and parallel, the single tweeter would need to be 4 ohm though.

the Penta has 9 drivers, and I need to replace the 4 midrange anyway, and a few others, so I may as well change them all if I can use the external 3 way active crossover (Behringer CX3400)  that I bought ages ago for another project

http://www.behringer.com/EN/Products/CX3400.aspx