This is the sixth and final part of the Bang & Olufsen Beolab Penta restoration. For the original post, see:
Vintage Bang & Olufsen Penta Restoration “Project Twins” – Part 1
This project was completed before my first child was born. I have a few additional B&O projects I’d like to complete but time is more limited with the addition to my family. It was grueling to complete in my workshop which topped off above 110 degrees on many days. It was however extremely rewarding and I absolutely love the sound of these speakers. To the best of my recollection, they sound better than the new pair I auditioned in New York back when I was still in high school in the early 90′s. So, here are the pictures of my labor of love:
Almost compete right speaker next to a Beolab 8000. Waiting for new closure before attaching final front panel:
Almost compete left speaker next to a Beolab 8000. Waiting for new closure before attaching final front panel:
Straightened out top speaker cap:
Groove between stainless steel was painted black to match the new black paint on the other plastic panels:
Fresh coat of stain black paint on all gray plastic parts. This shot is reflecting the color of the carpet a bit. The color presents darker in person:
New stainless panels revealed. Beautifully straight without a single fingerprint:
Final picture of the restored speakers:
{ 25 comments… read them below or add one }
Thanks Alan!
Unfortunately, I don’t have the parameters for the midrange drivers. Depending on when they were manufactured, the drivers might says Nokia, but I think they are the same. Since most of the drivers out there have likely changed due to age, you might want to get your hands on a new one before doing your tests. Last time I checked, B&O still had replacement drivers, albeit expensive.
A tri-amp setup could be really interesting. I believe I read about someone who did that with some ICE amps a while back. IIRC, he was very happy with the results.
Good luck and keep me posted as your project progresses!
Nice workmanship! The folks at B&O would be proud!
I used to sell B&O when I was in college. I recently bought 2 pairs of Pentas (1 pr Mk1 & 1 pair MkII). The Mk1′s work great. The midranges in the MkII’s need new surrounds.
Do you know the Thiele/Small parameters for the midrange driver? They can be determined using a $100 test kit like http://youtu.be/dARRX-tZpg4.
I think SEAS makes the driver for B&O. Perhaps someone has obtained the T/S parameters for the SEAS model #? Any pointers/help is much appreciated!
I’m considering a project to tri-amp one of my pairs. I have a high quality stereo active crossover and amps. This is probably looked down upon by true B&O fans, but I thought it would be an interesting project. Thoughts?
Thanks,
Alan
Jim,
Thanks so much! So nice to hear from other B&O fans in Texas. I gave up on vinyl years ago when I wanted to digitize everything, but I’ll take you up on the offer if I get back into it. The best glue is Aleene’s Original Tacky Glue. You can get it at craft stores anywhere in central Texas. I believe I picked mine up at Michaels, or Hobby Lobby. So are you saying that the Penta’s sound fine with music through the BS9000 but distorted from the Sony receiver? I’m just trying to understand the problem. Sorry for any delay in my responses. I’m in the middle of moving.
Cheers,
Eric
Hi Eric. I’m so glad I stumbled onto your website. WOW! Great stuff!!
I have a pair of Penta IIIs that I am about to re-foam. What is the best glue to use? Your re-foams look so clean and professional. Beautiful work!
My TV surround sound is connected to the passive side. Recently, I have had to turn them way down because of EXTREME distortion when any bass is present. I am using a Sony AV receiver.
I run my BS9000 through the active amps and it sounds perfect so I’m thinking that it must be the sony amp.
Your thoughts would be greatly appreciated.
Best regards.
Jim
Monte,
The 6603 is the Mk. I.
On all of the Penta’s I’ve seen, the top cap is held in place with two strips of very strong double sided tape. I used a heat gun and lots of finesse to remove them without damaging them. Good luck!
Eric, what a great project and nicely doccumented!
I have been searching all over and your project is just what I have been looking for.
I am helping a friend redo a set of these but I am not sure what model it is. All I can find is the model number 6603. Would you know what Penta (MKI, II, or III) they would be similar to?
I am haveing a problem with one of the amp lights staying amber. I cannot find any burnt components or hot spots on the board. I will replace all the caps/potentiometers and test the other components as your suggested earlier.
Also, before I start with the top section, how is the top aluminum cap removed? Is it just stuck on with two sided tape? These speakers have been kept in very nice conditiona and I don’t want to mess up the beautiful look.
Thanks and that is a very professional job on your speakers!
Doug,
First try switching the right and left channel to try to isolate whether or not it’s the receiver. Are you using the receiver’s speaker out directly to the Penta as a passive speaker? Or, are you using an RCA out from the receiver to the Penta amp?
Eric
Hey Eric,
Great restoration job by the way! I currently have 8 Pentas & only 4 are working properly now. I have 2 hooked up to a Pioneer Elite receiver as a part of a surround sound system and on just one side I have had 3 speakers start to pop & buzz & then shut down. Could it be the Receiver? Also, would you know where I could get them repaired in the Chicagoland area?
Thanks!
Doug
Allan,
To my knowledge, I don’t think B&O still stocks that item. I’ve bought a few spare Penta parts from: http://myworld.ebay.com/parts-bay. You might try contacting them to see if they have any, but I didn’t see any listed currently.
Good luck and thanks!
Eric
Hi.
I just must say: What a job. Your Beolab Penta looks like a million.
I have a pair of Penta MK2 but I have a problem.
I´m looking for the Display Glass Part number. 3320132 for both speakers.
Can you please help me. I can´t finde them anywhere.
Allan Koch
Denmark
Alejandro,
Check http://www.hifi-manuals.com or http://www.beoworld.org/manuals.asp (subscription required)
hello I’m repairing the amplifier will have some diagram that I find the fault, thanks
Thanks Roy, they were certainly a labor of love. Once things settle down, I’ll have a few more restoration projects posted, but sleep is quite limited with a new baby in the house.
Ryan, You have to keep them stainless! It’s ok to paint the plastic parts, but the metal is what makes them so distinctive. I’d love to see the condition of the ones you found. Feel free to email me pictures: http://egoh.com/contact/
Wow, I just found some in the garage of a house I bought. They are in bad shape, but nothing like what yours were. I wish I had the know how, to do what you’ve done. I wish I could just paint the whole things flat black.
NICE JOB!!! You my friend are an Artist. Having built a few Fried Transmission line speaker kits I can see the fine work, attention to detail and love of the job. It was a pleasure to read your story and follow your processes.
Thanks A LOT LOT LOT!!!
I tried doing research on this stuff but I have absolutely NO idea what’s going on with this(I did try to fix my cars before when I was in college a couple years back, because of lack of good tech guys in Tucson AZ, and I did ok hahaa) but this time I totally failed. Maybe, because of lack of time from work and stress. My brain seems not functioning haha. But yeah, like you just said I should take it to some local tech(way too expensive to send them back to B&O) to check them up with a full service since I am planning to keep them as long as I am still standing on this earth lol.
Btw, I think I will kinda rebuild it with new mesh n stuff. I will send a couple of pictures of before and after to you, just to share the pleasure coz you look like a B&O fan like I am. hahah
Again. I am appreciated with your precious time and reply!!
Km
Km,
Thanks for the kind words. The amplifier is going into protection mode, most likely because some of the components need replacing. The likely culprits are any (all) of the electrolytic capacitors which dry up with age and need replacement, the two adjustment potentiometers which also deteriorate with age, and possibly the transistors. At this age, the amplifier really needs a full service to bring it back to give it another 10-20 years of service.
Oh, and don’t try using it any more since it can do more damage.
Cheers,
Eric
Hi Eric
Your work is absolutely amazing!! I wish I could have your skill to get my penta 1 reborn like this. Sadly I dont have such skills, knowledge and space(since moved back to HongKong from states) to do that. By the way, I have been having trouble with one of the speaker.
One of them stopped working. I put both of them on “AUTO” (whenever you connect your speakers to your ipod they automatically turn on), they usually turn to “GREEN” light when the speakers work but somehow one of them turned to yellow(orange?) and it doesn’t have any sound but only a “POP” and when I tried to turn it off by switching to “OFF”, it doesnt turn off and the light is still on “Yellow”.
Now, sometimes it turns on but even if its on the sound would go totally off with no sound or some weird sound like sizzling. I heard it is about the amp or something.
I hope you can help me on this so I know whats going on and take it (maybe both of them since they are old) to check. Or do you have any suggestion/advise for me?
Appreciated!!!
Km
Eddie,
The resistors and coils likely burned out due to shorted electrolytic capacitors. You’ll need to likely replace all of them while replacing the other damaged components. I believe there are three versions of this crossover floating around. My Pentas are MKI but have MKII crossovers, so you might have to check all versions until you find the one that matches what you have.
If you have the same crossover as I do,
L6 on the bass is a 1.8mH air coil
L3 on the midrange is 100uH air coil
I believe you’re in Europe, but I’ve had good luck working with Mark at http://meniscusaudio.com for custom wound coils.
Good luck!
Hi Eric
I just disassembled my Penta s , and discovered that I had the same promlem with burnt resistors and coils.
Do you have the values for the L6 coil on the Bas and treble filter and the L3 coil on the midrange filter ?
I have looked at other sites with the penta filter but they do not describe the same values of caps and resistors as on the filters i Have. I do not think that they are the same. But looking at your pictures your filters look alot like mine.
Best regards
Eddie
Hi Eric
Congrats with the newborn. Thats alot of work.
I have ordered the Aleene’s Original Tacky Glue and also the cloth with some strech.
Best regards
Ed
Ed,
I’ll see what I can do, but it might take a little while since I have a newborn at home and things are a bit hectic. But, there isn’t a whole lot to see. Just rough cut fabric and some Aleene’s Original Tacky Glue residue.
Cheers,
Eric
Hi Eric
Thanks for your reply.
The jig sounds like a good idea.
Would it be too much to ask to se a foto of the backside og the top and bottom grills?
Best regards
Ed
Ed,
There are two ways to deal with this: 1) Make a jig 2) Use stretch fabric
I’ve done both for different B&O speakers. Method #2 is easier. In either case, you’re going to need a ton of clamps. Unfortunately, I didn’t take pictures of how I replaced the cloth, but I’ll try my best to explain.
1) You’ll need to make a jig out of wood that will restrict the frame from flexing too much inward. This way, you’ll still be able to stretch the fabric while not making the frames into an hourglass shape. I usually build the jig to be slightly smaller than the speaker so that there is still extra tension once the grille is installed to take out any remaining wrinkles or creases.
2) The easiest thing to do is to buy fabric that has a lot of stretch to it. In the US, fabric stores sell “dance fabric” which has some elastic to it. It’s available in many colors and finishes. I used matte black on these Pentas. Since the fabric is so stretchy, it’s much easier to get all the wrinkles out. The lower grilles are a breeze with this fabric. The upper grilles can still be challenging on the very top, but with some patience and a ton of claps, you can get it perfect.
Good luck!
Eric
Nice work
I have a pair of Beovox Penta with torn cloth
How would one replace the front coth. I have tried with bad result as the cloth frame is very soft and bends.
Best regards
Ed
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