Philips LBB-9020 (Gut Shots)

WhinyLittleRunt

WhinyLittleRunt

Member
In my quest to find a working Philips LBB-9020, I decided to post the pictures from my troubleshooting steps of the innards of this thing. Maybe this will help someone else as there is really nothing at all on the internet about these mics.

Back:


Model:


Front with on/off switch:


Top view:


With DIN connector removed for access:


Cover partway off:


Cover removed:


Closeup of circuit board:


Capsule:


Another shot of the top of circuit board:


Made by AKG?:


The capsule on this thing is contained, or at least it looks to be. There was really not much to see unfortunately. The only thing that was of real interest was that AKG stamp on the back of the circuit board. I would still really love to find out when this was made. Also, the 3-pin din connector needs an adapter to XLR which could also be part of the problem I was having with this thing if the wiring was not correct and I just didn't know it. This is the second one I received that didn't work and I thought the capsule was shot, and unfortunately there was really no way to know as it is self-contained. Hopefully these pics help somewhat for anyone else who owns one of these.
 
It is.

After the first one didn't work, I tried really hard to chalk this one up to user error, though I got nothing even bypassing the board and coming straight off the capsule wires.

Comes apart really easy, only have to de-solder the wires from the DIN connection and the cover just slides off.
 
looks like a dynamic intended for use with a tape recorder (1/8" tape) i base this on it looks like the switch on the side like the one i used to have. IIRC the switch was for remote switching.
I could be wrong.
Is the round thing a transformer? looks like a rudimentary one.
Did you stick the DMM (digital multimeter) on the capsule to measure resistance?
It was probabaly that the capsule was shot.
 
>Is the round thing a transformer? looks like a rudimentary one.

Well, half of one! It is an inductor, which is switched in to make the high pass filter circuit.
 
Once you've got resistance, inductance and capacitance nailed, you are ready for impedance!
Now you can really call yourself an engineer ;)
 
kip4 said:
looks like a dynamic intended for use with a tape recorder (1/8" tape) i base this on it looks like the switch on the side like the one i used to have. IIRC the switch was for remote switching.
I could be wrong.
Click to expand...

Supposedly the switch is a bass roll off or something; on the first one I got, there was a barely legible "Musik" penciled in on the housing at the bottom of the switch.

The main switch is an on/Off. Supposedly these are great sounding mics... Based on what little review I can find of them. One led me to believe it was supposed to be an MD421 clone...
 
Thanks I still don't get impedance totally yet and it will be a long time until I call myself an engineer. I'm learning everyday a little more.
It resembles an md it would be interesting to hear it.
 
WhinyLittleRunt said:
Supposedly the switch is a bass roll off or something; on the first one I got, there was a barely legible "Musik" penciled in on the housing at the bottom of the switch.
Click to expand...

Yes, as I posted above, the inductor forms a high pass filter aka "bass roll off".
They are often called 'Voice' and 'Music' settings. The filter helps compensate for bass-boosting proximity effect when speaking close up.
 
So what would be the correct adapter (DIN, Tuchel etc) to XLR that I would need to adapt a mic like this to XLR?

When I got the one posted, it did come with an adapter cable. But I'm having a hard time finding one that looked exactly alike (3-pin). I also read that the pins on this mic may have been wired differently so just plugging in an adapter straight through to xlr would possibly not work... Can anyone confirm this, or are these connections pretty standard prior to XLR being the mainstay?
 
Bumping this because I have a question about wiring up DIN to XLR adapters...

I just bought some adapters from Allied Electronics, Lumberg KV30 3-pin DIN. Now, I don't want to fry anything on the mics that I am yet to receive, so as far as wiring these adapters to XLR, do I assume that the pinout on the mic will be the same on the XLR side? Because I've read up on this a little, and I guess I would have to determine which one is hot, etc. Anyone think they could point that out to me just by looking at the pics of the circuit board? The bad mics did come with a pre-made adapter cable and I did open it up but didn't document the pinout... not sure if that cable was even wired correctly.
 
With the KV30 be careful to make sure that the thread matches the mic. Usually they do, but if you have to force it then don't be tempted to overtighten it or you can jam the locking ring.

On the photos you posted you had unsoldered the wires already so I can't say what went where, but read and blue are signal and black is ground. One would guess that red is hot, but that is by no means certain.

Normally with these mics the middle pin will be ground (equivalent of pin 1 on the XLR), and the outer two pins are signal hot and cold.

Normally DIN pin 1 is hot, but occasionally the polarity is reversed, so check phase against a known good mic. For example, most Beyer B260s with DIN plugs have hot on pin one, but every so often you find one that is reversed!

Cheers
Stewart
 
Excellent, thanks for that - I guess that would all make sense. All I worry about it frying the capsule if I happen to connect things wrong. Do I have to worry about that? If I wire in reverse, for example, I should just get nothing, right? I shouldn't blow anything up though?
 
If you reverse hot and cold, your signal will be reverse phase.

If you accidentally connect one side of the capsule to ground then you will either get no signal, or a 6dB reduction in output, depending on how your mixer is wired.

The only opportunity for damage is if you ground one side of the capsule and then turn on phantom power. Then you are putting a DC voltage and current through the capsule, which is generally a bad plan.
 
Excellent, thanks for all your help.
I received the mics yesterday and everything is working great.

I'm sure it's just the cable, but when I built my 2 cables with some nice quality Belden cable I had left-over from an old Neotek console, I got a NASTY ground buzz all over everything. I mean, you touch the grill of the mic and you got buzz. It was definitely in the cable though, because I finally just sacrificed one of my older XLR cables and when I wired that up to my DIN plug, it was perfect.

The reason I find it odd, is because it is shielded cable, and I also used the same cable (different color only, identical otherwise) when I was wiring up my XLR patch block on the wall of my control room to the back of my board. And when I did that, I didn't even use the extra ground lugs; I just did a straight-through female to male plug right to the board and there is absolutely no noise.

On the cable I made for the mic, I routed the ground through the extra ground lugs on both ends and still the thing buzzes like hell. I couldn't see any reason the XLR cable was any better other than it was thicker and the ground wire was beefier... Any ideas? It isn't critical either way now that they're working...
 
Bump.

I just got a few of these in today with a larger batch of used mics, I'll be seeing into them later today, if I can find some time.

Ussually old Philips mics don't really cut it, so I was surprised to find a whole thread dedicated to them here, while I was trying to dig up some info via Google.

Is anyone of you using these mics? And on what?
 
Am in the same boat as you, Chris.
Got some in on a batch order of used microphones. That was a few years ago and I still haven't gotten around to them.
 
Seems you got hold off two poor condition LBB 9020's.

I have an almost mint condition 9020/15, no switch, no bass roll off, in its box, the plug has never had solder applied to it, no scratches, so is probably almost unused, except like me, using a different connector. It works fantastic, tried it against a sennenheiser (can't spell) 835, it compares well, a great general pupose quality microphone, worthy of a place in a collection or as a used vintage piece of kit.. Might be interested in selling, interested? where are you in the world?
 
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