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Beolab Penta MK3 - Weichen und Schnickschnack (Wiring diagram)

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Kwuensch
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Kwuensch posted on Wed, Oct 23 2019 4:38 PM

Moin, 
ich bin jetzt stolzer Besitzer der Penta MK3 und habe noch meine kleinen Wehwehchen.
Als ich sie mit meinen M70 verglichen habe, musst ich Festellen, dass die Penta in den Höhen und in den Tiefen etwas schwach auf der Brust sind. Das ganze ist natürlich auch ein bisschen unfair zu vergleichen und ich meine hier nicht den "Badewannensound", aber ich hätte die Penta schon ganz gerne so, wie ich mir deren Potential vorstelle.

Vllt. einmal mehr zu meiner Kette:
Beogram 1000 und/oder Beogram 3300 an einem Röhren-Pre + Beosystem 4500(alles bis auf Plattenspieler) + Powerlink an Penta bzw. vorher über Lautsprecherkabel an die M70

So, jetzt bin ich im Archiv auf einen Post gestoßen, wo Die_Bogener (habe ihn auch via Mail kontaktiert, aber keine Antwort bekommen | okay, es ist auch erst ein Tag vergangen Smile ) sehr detailliert beschrieben hat, wie er seine Frequenzweiche optimiert, bzw. bestückt hat. Leider sind da die Bilder hops gegangen und das Servicemanual der 6631 zeigt mir irgendwie nicht das richtige Diagramm für die Weichen. Ich habe auch nur ein Diagram im Netz finden können.

Kann mir da jemand etwas zu Rat stehen oder hat das jemand von euch schon einmal gemacht?

Also im Detail, Weichen überbrücken und neue Kondensatoren etc.
Sicken und der andere Kram sind top und machen mir hier erstmal keine Probleme.

Freue mich über eure Hilfe!

Gruß Kaya

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Manbearpig
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Dillen:

Those blue radial Maxcap capacitors will be bad by now.
The boards are largely identical to the ones in the first post, - they can have either radial or axial capacitors fitted.
To preserve or reachieve the original sound I suggest you fit new electrolytic capacitors instead of the old electrolyctics. No MKPs or other film capacitors.
In the best of cases there won't be any discernible difference from electrolytics, in the worst of cases the speakers will end up sounding
"modern" (some owners may like that), but they can end up sounding far from intended - sterile and wearing on the ears compared to the
original soft and pleasant (B&O-) sound of the electrolytic capacitors, to the point of relief when switched off.
Electrolytics was also what B&O chose to use for the Pentas.

Martin

 

Hello there,

may I jump in and curiously ask where that change of mind comes from or what happened? I can very well remember that in the older threads, where Die_Bogener first suggested all those modifications, you were full of praise and claimed quite different things. Or am I getting something wrong here?

Greetings,

Kai

 

 

Dillen
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Dillen replied on Sun, Oct 27 2019 11:02 AM

I don't recall praising the use of film capacitors in crossovers in particular.
At first I thought it was a great idea to replace electrolytic capacitors with film capacitors. Mainly because they (at least in theory) should last forever.
I even made capacitor kits containing film capacitors for several of the larger B&O speaker models.
But many buyers reported back, that they didn't like the sound of the speakers after the rebuild to film, and a few
even asked me to revert their speakers back to electrolytics.
I wondered about that, but also had to admit never listening seriously and for longer periods of time to speakers rebuilt
with film capacitors, so I sat down and did exactly that. My conclusion was, that they were right, - the sound was wearing on the ears.
Where I could listen to "original" speakers for hours without experiencing any fatigue, I grew tired of listening to
the ones rebuilt with film capacitors fairly fast. In the best of cases I honestly couldn't tell any difference from electrolytics, but in the worst of
cases I felt a relief when switching off.
I also came to the conclusion that the speakers, filters and everything was designed for using electrolytics, and
if any other type of capacitor would've made them better speakers, B&O would've used that.

I no longer provide film capacitor kits.
Feedback from buyers made me aware, and I feel that the, at times very steep, prices of the film capacitors can't be justified.
As mentioned earlier, some owners may actually like the sound of the film capacitors, - a sound that I like to refer to as "modern",
because it seems that's where many speaker producers are heading, but it's not the typical and well-known "B&O-sound", - it's not
what B&O intended and it's not the original and warm sound, I prefer myself.
Another thing is, that the film capacitors are often quite bulky in size and rarely fit particularly well in the filter boards.
This alone can be a challenge to some DIY'ers.
Some film capacitor types are so big they need to be placed elsewhere inside the speaker cabinet, which again requires extended lead lengths = not good for cap specs.

What I recall praising was Die_Bogeners modifications to the amplifier section of Beolab Penta.
A few coupling capacitors and some OpAmps are replaced for newer types.
This is not done to improve the sound reproduction as such, - actually the sound isn't colored notably, but it dramatically
improves the signal/noise ratio, an area where the active Pentas with their "volume control" constantly at max can use all attention obtainable, and
it also takes care of certain older OpAmp types that are notorious for injecting their own noise into the signal, so is absolutely worth doing.
These modifications also got included (with Die_Bogeners accept) in the amplifier rebuild kits I make.

But it's all a matter of taste.
If you like the "modern" sound then by all means go ahead and fit film caps (keep leads short and fasten everything so nothing rattles or breaks their solder joints), but if you want the original sound I recommend staying with electrolytics.

Martin

Kwuensch
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Hey Dillon,

I have now equipped the right speaker with the MKPs and hear what you mean.

the warm sound goes away and it gets very sterile.  is that possibly at the depths?  I'm still considering to equip the left because otherwise I have no complete system.

Manbearpig
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I have compared moded and unmoded examples of speakers and amplifiers. I have never made that experience. The mods Die_Bogener suggested clear things up, increase bass and treble. But obviously it also depends on who does the work and not only on the components used. Die_Bogener himself only delivers perfect work and honestly, from a theoretical point alone, his suggestions make much sense. The practical result lives up to that, although, of course, no wonders are to be expected.

I do not really buy that "B&O knew what they were doing" argument. Sorry, but although the Pentas were a very expensive to manufacture speaker and top of the range at the time, times where B&O tried to excel sonically were long over by then. The Penta turned out to be a mass product and costs obviously did play a role. Some of the components used were mediocre or even below that. Just look at those cheap resin enclosures for the midrange drivers - a disgrace to anybody who knows what some of the older spearkers looked like. Some of the electronic components definitely also were not the best (although drivers were still pretty decent). Beogram 4000, Beolab 5000, Beomaster 4400, even the Quad system, and some others - those were the times where costs did not matter to an equal extent. And you can tell. An overhauled Beomaster from that time paired with Beovox M100 will give any modern system even when paired with Beolab 5s a run for its money.

I prefer the moded systems sonically and electronically since they will last as you also highlight. Higher quality compomnents with better specs used in a savvy way won't hurt. One last remark: Die_Bogener knows his stuff. He, from my point of view, is one of the most knowledgable guys when it comes to Beosystem 4500 - 7000, Beocenter 9500, Beolink 7000, Pentas, RLs, but also the TVs and VCRs of the time.

Greetings,

Kai

Kwuensch
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Kwuensch replied on Sun, Oct 27 2019 10:01 PM

Hey Manbearpig,

I have just installed the MKPs in the crossover and, if the sound stays that way, I have to agree with Dillon.

I do not know if the capacitors need time to burn in. But if they stay that way, the warm sound is gone. 
Unfortunately, I do not know much about the mods of Die_bogener, but an increase in heights does not seem to make sense to me now. I do not want to doubt it, what I read seemed thought out to me.

Best
Kaya 

Stereomensch
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Du kannst mit Manbearpig auch Deutsch reden, ist schließlich seine Muttersprache Smile

 

Hast du denn jetzt nachgeguckt, was für einen Hochtöner du hast?

 

Wenn du zu den Bogeners Kontakt haben willst, schreib mal Ulf Kiener an.

Dillen
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Dillen replied on Mon, Oct 28 2019 6:47 AM

I am not questioning Die_Bogeners skills and knowledge at all.
As mentioned, I have actually adopted a few of his ideas, and I have sent several B&O owners, asking for repairs in Germany, to him over the years.
He may like the sound of Pentas fitted with MKP capacitors and recommend it to others.
I just don't.

Despite many people wanting it to be - or wishing that it was - Penta was never an audiophile speaker.
It wasn't intended to be and it won't be unless drastically redesigned, which in my opinion would be a shame.
Penta is in my opinion one of the most beautiful speakers ever built, and it's an excellent speaker in its
own right, with an absolutely pleasant and nice sound.
The engineers did their best with their knowledge, experience and not least the limitations of the design they were presented with, and
clearly they must have faced a couple of challenges in the process; Cabinet volume and width quickly springs to mind.
Usually the drivers are the most difficult parts as their T/S parameters often seem to call for cabinet volumes that just cannot
be granted, resonance points etc. but B&O had some drivers custom produced and ended up with what I think is a more than
acceptable result, considering the design.
I'm sure they would have liked to introduce a 10-inch woofer somewhere, - it just couldn't be done, so they settled for
a group of four 5-inch drivers (pairing identical woofers is something that many speaker designers warn against doing, but something
that B&O have managed to succeed in since the 1970s (4700/P45/RL60,140 etc.)

When you judge Penta speakers performance you must keep in mind to sit down in a normal listening position.
Not stand up in front of the speaker as many people tend to do and as the speakers design somehow asks of you.
Generally, speakers should be placed at ear height - your ear height when listening, that is - which
for most owners of f.e. wall-panel speakers comes out as surprisingly low and why speakers like f.e. Beovox S45-2 should be on
stands rather than placed directly on the floor.
Pentas midrange and tweeter section is at the right height for this, and its woofers are distributed
above and below accordingly.

I agree, that many of the older, discretely built, amplifiers sound excellent, and I would almost always prefer to listen to one
of them rather than anything modern. Just as the case is with speakers - as mentioned, it seems to be the sound trend of the time.
It can make a pleasant sound, well, but the Beomaster 6000/4-channel really doesn't qualify to be up there
with Beomaster 4400 and 8000 in my opinion. It's a great design but in effect it is really nothing more than two Beomaster 901s.

Several of the newer, and highly praised, B&O speakers use composite enclosures and cabinets.
I'm a bit curious as to how you would improve the Pentas midrange enclosure?
And what would be achieved?

Martin

Kwuensch
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Kwuensch replied on Mon, Oct 28 2019 11:28 AM

Hey Stereomensch,
werde es mir merken ;)
Hatte Die_Bogener schon angeschrieben, aber warscheinlich auf eine alte Mailadresse, da ich gesehen hatte, dass er wohl hier im Forum nicht mehr wirklich aktiv ist.
Ich habe auch nochmal geschaut und meine, dass das die mit den Plastikkappen sind.
hier noch ein Foto:
 

Stereomensch
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Und ja, du hast die alte Version! :)

 

Bezüglich Umbauvorschlag:

Schau mal hier:

https://forum.beoworld.org/forums/t/17557.aspx?PageIndex=2

 

Hermann (Hfinette) hat den Umbau gemacht, den kannst du auch sonst mal fragen.

Gruss Christian

Kwuensch
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Dank dir für den Link!
Ich glaube ich habe so ziemlich alles gelesen, was zu dem Thema geschrieben wurde.
Anfangs hatte ich das Problem, dass ich mich an dem falschen Diagramm orientiert habe und da so meine konkreten Problemchen hatte.
Ich bin auch ehrlich, ich bin kein Elektroingenieur, sondern eher ein Typ mit einem Lötkolben und Interesse.

Jetzt habe ich, wie gesagt, die ganzen alten Roedersteiner durch Jantzen MKPs ersetzt und höre den Unterschied.
Was Dillen sagt, kann ich (zumindestens bis jetzt) bestätigen. Durch den Umbau der MKPs habe ich einen Verlust des Warmen Sounds. Die Höhen sind prägnanter geworden und das wollte ich auch, aber der "Verlust" ist ganz klar in den Mitten und in Tiefen.
Ich überlege momentan wieder die alten (falls ich sie nicht beschädigt habe) in den Tiefenbereichen einzubauen, oder die Verbindungen, ich habe hier Silber verwendet, durch Kupfer zu tauschen. (Ist für mich eigentlich Schwachsinn, aber vllt. sind die Kabel auch einfach zu dünn).
oder ich mache weiter und baue á la Die-Bogener um (wozu ich auch tendiere).
Die Hochtöner werde ich erstmal nicht wechseln, es sei denn, ich finde zufällig ein Paar in der Bucht.
Hattest du die Pentas vor und nach dem Umbau gehört?
Was hast du alles geändert? Welcher Unterschied war dann?

Viele Grüße
Kaya

Dillen
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Dillen replied on Mon, Oct 28 2019 2:24 PM

You really should compare MKPs to fresh electrolytics - not to old and worn out electrolytics.

Martin

Kwuensch
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@dillen

can you recommend which ones?

Manbearpig
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Dillen:
I am not questioning Die_Bogeners skills and knowledge at all.
As mentioned, I have actually adopted a few of his ideas, and I have sent several B&O owners, asking for repairs in Germany, to him over the years.
He may like the sound of Pentas fitted with MKP capacitors and recommend it to others.
I just don't.

That is perfectly fine. It just seems sometimes that people tend to forget rather quickly. Many of the old threads and in particular the pictures are unfortunately no longer available. But Die_Bogener was one of the most active, creative, and knowledgable contributors. Admittedly very few members formerly kindly asking for his advice are putting the exact same ideas and contributions they used to appreciate so much earlier now down. That is a bit irritating to me as far as trustworthiness is concerned. I am not particularly addressing you, not the least in fact, but I have observed such a tendency in general. I, however, can still very well remember the times when Die_Bogener was more active on here and many were still reaching out for him, asking for his advice, and having nothing but praise for his ideas and contributions.

Dillen:
Despite many people wanting it to be - or wishing that it was - Penta was never an audiophile speaker.
It wasn't intended to be and it won't be unless drastically redesigned, which in my opinion would be a shame.
Penta is in my opinion one of the most beautiful speakers ever built, and it's an excellent speaker in its
own right, with an absolutely pleasant and nice sound.
The engineers did their best with their knowledge, experience and not least the limitations of the design they were presented with, and
clearly they must have faced a couple of challenges in the process; Cabinet volume and width quickly springs to mind.
Usually the drivers are the most difficult parts as their T/S parameters often seem to call for cabinet volumes that just cannot
be granted, resonance points etc. but B&O had some drivers custom produced and ended up with what I think is a more than
acceptable result, considering the design.
I'm sure they would have liked to introduce a 10-inch woofer somewhere, - it just couldn't be done, so they settled for
a group of four 5-inch drivers (pairing identical woofers is something that many speaker designers warn against doing, but something
that B&O have managed to succeed in since the 1970s (4700/P45/RL60,140 etc.)

I totally agree, and we are probably in a minority on that, but Penta is an astonishingly beautiful speaker. I have thought multiple times about swapping to Beolab 1s or Beolab 9s, but just couldn't convince myself that overall this will really be an improvement. I find Pentas to be utterly beautiful, but know many that will totally oppose that point of view. As far as Pentas being audiophile of not, it all depends. I prefer my M75s, but Pentas are a damn nice sounding speaker for what they are. Still one of the best in B&O's portfolio of active speakers if you ask me. Their strengths particularly shine when playing loud.

Dillen:
I agree, that many of the older, discretely built, amplifiers sound excellent, and I would almost always prefer to listen to one
of them rather than anything modern. Just as the case is with speakers - as mentioned, it seems to be the sound trend of the time.
It can make a pleasant sound, well, but the Beomaster 6000/4-channel really doesn't qualify to be up there
with Beomaster 4400 and 8000 in my opinion. It's a great design but in effect it is really nothing more than two Beomaster 901s.

Ok, this is the tricky part. First, I was talking built quality, not sound quality. And built quality of the 6000 Quad ranks definitely up there in my book. However, as far as sound quality is concerned, I don't agree. I have owned roughly 10 Quads and stated before on the forum what sometimes seems to be forgotten. First, there are different generations of the Quad that showed remarkable differences electronically. The last generation for example didn't reduce volume when switching to double stereo, whereas the first generation did. Second, some of my Quads sounded surprisingly different. For example, one played as lound on volume 5 as some others did on volume 10. And no, there were no electronic defects. The Quad was B&O's first 4-channel receiver apparently and they were still experimenting with the design. Therefore, many more or less significant differences exist between individual models. There was no serial production back then. Individual examples were not entirely standardized. To make a long story short, I figured that there are well sounding Quads that for me rank up there with the other receivers named. However, they are few. What is more, replacing capacitors didn't do much good to the sound on the Quad. But that is just my experience. Of the many examples I have owned, I still possess one that is totally restored but with the original capacitors still fitted wherever possible. Needless to say that it is the example that outperformed all the others I have had, no matter whether fully resored with capacitors replaced or not. It is one of the last made and presumably was hardly used by the previous owner. Whether this is generalizable, I do not know.

My friend who helps me with the restaurations of the Quad and has done many (>20) was pretty surprised by the statement that the Quad essentially is two 901s in one cabinet. This information is repeated over and over again on here, but he doesn't agree. What is more, he actually likes the 901 very much as far as built quality, electronic design, and performance is concerned. Therefore, even if the Quad essentially was two 901s combined, that is not necessarily a bad thing.

Dillen:
Several of the newer, and highly praised, B&O speakers use composite enclosures and cabinets.
I'm a bit curious as to how you would improve the Pentas midrange enclosure?
And what would be achieved?

The design is functional. But so are the Beogram 7000 etc. designs. It is just cheaply made.

Greetings,

Kai

TanteInge
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Moin,

ich kann gar nicht mehr zählen, wieviele Geräte der Martin (Bogener) für mich und auch Kumpels von mir repariert und klanglich optimiert hat. Von der Ouverture über diverse 7000er Teile, Lautsprecher bis hin zu einem MCL2P und sogar einem SONY Big Smile.

Für mich ist er ein regelrechter Held und ohne ihn wären meine B&O Errungenschaften längst im Elektroschrott bzw. als defekt in der Bucht verramscht.

Zum eigentlichen Thema der Art der Modifikationen: ich persönlich liebe den „Bogener Sound“: abgrundtiefe Bässe und kristallklare Höhen. Davor war der out-of-the-box Klang von B&O ja okay, aber eben nur okay. Erst wenn diverse Teile (ELKO‘s usw.) gegen andere/höherwertigere getauscht worden sind, weiß man, was noch alles geht.

Vielleicht liest er ja gerade „still“ mit und dann habe ich eine weitere Möglichkeit gefunden, mich zu bedanken 🙏🏼

In diesem Sinne grüßt,

TanteInge

My B&O:

  • Living-Room: BeoMaster 7000 (white), BeoGram 7000 CD (white), BeoGram 6500 Vinyl (white), BeoCord 6500 Tape (White), KEF LS 50 (white) with Yamaha NS-SW 300 Subwoofer (white)
  •  Guest-Room: BeoSound Ouverture, DeToma Stavolo 700 active (white), MCL2P, Technics SB-C700 (white)
  • 2x Beo4 (modded by LinVis), BeoCom 4 and A9 Keyring; Light-Manager by jbmedia
Kwuensch
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Moin,

Ich habe nun die Pentas länger laufen lassen und habe so ziemlich alles gehört, was ich gut kenne, sodass ich mir einen Eindruck machen kann (Wohlgemerkt immer alles Subjektiv).
Von "Eagles - Hell Freezes Over", über "Brian Bromberg" bis hin zu Nicolas Jaar etc. Meistens direkt von Platte oder via Flac vom Rechner. Ich könnte jetzt noch mehrere Alben aufzählen, das wäre aber am Thema vorbei.


Naja, was soll ich sagen...
Irgendwie verfliegt das vorherige Vermissen der "Wärme". Genau kann ich es aber auch nicht beschreiben. Entweder mussten sie sich einspielen und haben tiefen dazugewonnen, oder ich nehme sie mit der Zeit anders wahr.
Als ich die Pentas frisch stehen hatte, habe ich sie direkt mit den M70 verglichen und die waren viel präziser. Sie haben eine ganz andere "Auflösung vom Bühnenbild" gehabt, was ich dann als Potential gesehen habe, da sie wirklich nicht so gut geklungen haben.
Mittlerweile spielen sie allerdings ziemlich Ähnlich.
Der tausch der Kondensatoren war somit genau richtig. Ob es jetzt MKPs oder normale Bipolare Elkos sein sollten, war mir garnicht mal so wichtig. Es ging eher darum, den relativ dumpfe Klang zu beseitigen (Was wohl daran lag, dass die Kondensatoren tatsächlich Ihren Zenit überschritten hatten).

Durch viel Internetrecherche kam ich dann auf den Mod von Die_Bogener, wobei die Bilder leider fehlten. Interessiert hatte es mich dennoch, gerade weil so viele darüber berichtet haben.
Ob ich es noch umsetzte bleibt fraglich. Bin ganz froh darüber, sie revidiert zu haben, ohne dass etwas schief ging :)
Optimieren kann man da ja immer noch.

Irgendwann wird trotzdem der Moment kommen, wo ich mich frage, ob sie ohne die MKPs besser geklungen hätten. Das kann ich nicht ändern und liegt auch eher in -meiner- Natur. Ob ich sie dann wieder zurück baue oder so lasse, kann ich jetzt nicht beantworten.

Stereomensch bzw. Christophe hatte die Idee mit dem DSP, mit dem ich jetzt versuchen ein bisschen rum zu testen. Dazu werde ich mir den minidsp 2x4 ("hd" oder nicht "hd" werde ich später entscheiden) holen und und mir einen Adapter bauen, damit Powerlink trotzdem noch funktioniert, denn auf das Display möchte ich nun wirklich nicht mehr verzichten.

Ich danke euch allen, für die eure Hilfe und finde es schön, dass für die Pentas noch so viel Passion übrig ist.

Werde weiterhin berichten, wie es weitergeht und welche Erfahrung ich mit dem DSP mache.

Vielen Dank / Thank You!

Kaya


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