Definitive Technology BP20 Mod Thread

Tony M

I've heard on this forum many times, better cross-over components do enhance the already fine speakers.

The BP30s do sound balanced to me. Tonight though, I turned on the receiver when I stepped in the cottage, and I then changed the stations to find something besides a commercial. One station sounded like crap! I didn't remember that particular station sounding this bad, but it was. I switched stations some more and ...oh yea...out came some fine sounding music.

I've heard a ton of speakers here and I've owned 2 sets of BP10Bs. I loved their sound. Back then, I was jammed up and had little space to really enjoy them. Somewhere along the years, people would stop by and see what I'd sell. Pickers...some were. Anyway, I got money back, maybe a little more, and would go on with my painfilled life.

I regret selling a lot of things and those "Perfect and in their boxes" BP10Bs are up there in the top 10. 2 reasons but the bigger reason is told below.

A guy screwed me and didn't pay me the rest of what he owed me on those perfect BP10Bs. He gave me a down payment and never came back. He lived 60 miles away and I didn't know where exactly. I anguished for 2 whole years about getting back at him in bad ways. Then I started reading novels to get my mind off the con job he pulled. It worked. I moved on. Then a year later or something like that, I saw an ad for these BP30s plus some other stuff for 300.00. I emailed and got to go buy the package.

I still feel GOD and or karma had something to do with me being the first of 10 people who emailed after me after seeing that ad. I was lucky or blessed.

A lot of what I own or owned is a true blessing of wishes to find cool audio stuff fulfilled during tough times. The tough times have been pretty much over for 4 or 5 years now. I don't go looking for audio stuff except on FB marketplace and CL. Everyday almost, I check them out since I've made space now. But new purchases have to be special, really special now.

I'm still waiting on the Lottery Win wish to be fulfilled.

4Sounds

That was messed up. But look what you have now!:) Yeah ..upgrading components does enhance them. It's just true. Also I see nothing wrong with enjoying them as they are. For instance I have not changed my BP20,s at all. That reminds me..you should also look on Offer up they have some great finds. I found my BP20's for $350 on there. They are in perfect condition with the original boxes, manuals, and carpet spikes. The man even delivered them, stayed as I tested them, gave me the receipt showing he bought them in 1992 and that I'm the second owner. He also threw in 2 extra woofers and tweeters brand new from Definitive Technology. After seeing the speakers worked fine we sealed the deal and he left. I played them the whole day and they sounded... beautiful. The cabinets are this nice grey color that gives them an industrial look that I really like (they are a lighter grey than pictured). In short I don't think I want to change them at all. I have an extra pair of BP20 crossovers that I could tamper with just for fun though.




I'm a tweaker by nature upgrading my 10's afforded me opporunity to scratch that itch and learn some things I would not have otherwise. I like the technical and engineering part of audio as much as I enjoy music itself. So I do at some point look inside of every price of equipment I own..just to get some basic grasp of what's there and how it works....it's fun to me. In any case I still have all the original parts for my 10's should I for any reason ever want to take them back to factory status.

Thanks for sharing Tony!😎

Tony M

Those BP20's look brand new.

That's quite a nice story too. A man helping somebody else (you) out beyond the norm.

Others have reminded me of the OFFER UP site. I keep forgetting to search there.

At my age, 64, I have a ton of stories surrounding audio events.

Here's a quick one.
While yard saleing in a neighborhood event, I turned the corner to look on another street, and there they were, 150 ft. away maybe. I spoke to my wife, there's a set of JBL L5's on the left. She asked how I knew that. It was because I owned a set of L1 and L3's. I didn't see a woofer on the sides, so they probably were L5's. It was late in the morning too. I was shocked they were even there. Anyway, I asked how much? 20.00. each? I asked. No, for both, he said. I took the covers off and they looked good. He said he'd refund my money if they didn't work when I got them home. I think I gave him 40.00. They worked fine. I can remember playing "No Quarter" CD through them. That was a test CD I was using during that time. All JBL L1,3,5 series were awesome speakers to me. I regret selling all of them too. Their shape is pretty unique as are their grills. I'm going to go back in my sales book and see if I just had the L3s and not a set of L5's from that memory. They were JBL-L5s. Why did I ever sell them, I guess 300.00 was a good reason to pass them on.




I have a great story about a set of Technics SB7070 and a Pioneer SX1050 receiver I bought at a yard sale.



I don't think I ever opened up many speakers EXCEPT to find out why an individual speaker or tweeter wasn't playing.

I wanted to learn how to redo speaker crossovers 10+ years ago but still haven't.

4Sounds

Well it certainly not the best looking and I'm sure many flaws can be pointed out. But.. here it is in all of it's unorthodoxy. And naturally, I think I have one of the best sounding BP10's on the planet😉. This smoothed the highs and killed the bite, brought put midrange clarity and detail and more. The bass retained that thunderous quality but is more controlled and contured, with nice punch. The speakers sound free!




Didn't mean to hijack this BP20 post but I'm sure they won't mind if their lil brother BP10 get a lil attention.😊

VR3

Looks great!

4Sounds

Thanks Trey:)

Kiwiaudio

Hi Guys, first post ! I sent emails to a couple addresses i found for you VR3. Not sure if you are still into doing crossovers for folks, if not i understand. I can do it myself, but im a rookie compared to you. Im Rebuilding a pair of D/Tech BP20s and want to do crossover upgrades that are not too crazy. It has to go back in the hole though, as opposed to huge outside the box units.
Maybe if you are not doing rebuilds anymore, could you please recommend some components and values? I dont mind spending some coin on these, but i have a feeling i dont really need to.
My BP20s have the Definitive replacement drivers, and ill be using the Vifa D27TG-35 Tweeters, so basically oem.

Cheers,
Kiwi.

rooftop59

Kiwiaudio wrote: »

Hi Guys, first post ! I sent emails to a couple addresses i found for you VR3. Not sure if you are still into doing crossovers for folks, if not i understand. I can do it myself, but im a rookie compared to you. Im Rebuilding a pair of D/Tech BP20s and want to do crossover upgrades that are not too crazy. It has to go back in the hole though, as opposed to huge outside the box units.
Maybe if you are not doing rebuilds anymore, could you please recommend some components and values? I dont mind spending some coin on these, but i have a feeling i dont really need to.
My BP20s have the Definitive replacement drivers, and ill be using the Vifa D27TG-35 Tweeters, so basically oem.

Cheers,
Kiwi.

@VR3

Kiwiaudio

What do everyone use for speaker gaskets these days? Originals are shot and they are wafer thin foam.

pitdogg2

I've used this cut to width. You'll want then then cut to length diagonally instead of straight across to avoid air leaks. If your speaker is ported I guess it really doesn't matter.

https://www.homedepot.com/p/Armacell-2-in-x-30-ft-R-1-Foam-Insulation-Tape-TAP18230/100539553

Kiwiaudio

Can i just replace the caps and resistors with like values, but of higher quality ?

AndreE

Some sticky one side foam from a local hardware store but not to thick. There is a larger port nearby so keeping it tight is nice but not overly critical. Part’s connection should have a sale soon. 20% can help and Move you up in quality without adding cost. Caution to size as it’s a tight fit to port tube.

Kiwiaudio

Would anyone have an original single board Definitive Tech BP20 crossover laying around that i could buy? Ive modified both of mine and have a problem. I would like an original to help me troubleshoot.
A schematic would help too but i have no idea where to get one of those.

VR3

The crossover is pretty basic

What issue are you having

Kiwiaudio

Yes, it is a pretty simple one but somethings not right. All i did was replace the two caps and two resistors with like values but better components. I left the air core coil in the tweeter circuit alone, and the iron core coil in the woofer circuit alone.
I used a 15Mf Clarity cap and Jantzen superes resistors, values .5 and .82 on the tweeter circuit.
Solen cap on the woofer circuit.

Everything is soldered in exactly where it was before, though physical location a little different with the restrictions of the board. Its tight as you know !

On the woofer circuit with woofers connected, i get 4 ohms resistance at the input cup as expected.

On the tweeter circuit, i get 0 resistance at the input cups with the two 6Ohm tweeters connected in parallel as they should be. So somethings open. Tracing the circuit, i cannot see a problem.

Gardenstater

I don't know the circuit but capacitors do not pass DC current so you probably should get no reading/open on an ohmmeter for the tweeter circuit.

Kiwiaudio

Here are a couple of pics while i draw a schematic.

VR3

You definitely shouldn't see 0 ohm readings with a driver connected

But a few of those solder joints look suspect. Did you remove all of the old solder?

Kiwiaudio

Here is a crude schematic as i see it on the board.

Gardenstater

Yeah so if you jumper out the capacitor, then you'll get a resistance reading.

Kiwiaudio

Gardenstater wrote: »

I don't know the circuit but capacitors do not pass DC current so you probably should get no reading/open on an ohmmeter for the tweeter circuit.

I did notice that the components are in series, and the cap wont pass my multimeter probe set to impedance. With the tweeters hooked up though, i cannot get the 1.5volt battery test to make the speakers pop either !

Im just leery of connecting these up with the amplifier seeing no load !

Kiwiaudio

VR3 wrote: »

You definitely shouldn't see 0 ohm readings with a driver connected

But a few of those solder joints look suspect. Did you remove all of the old solder?

Yes, i used a solder sucker and braid. Admittedly, i could probably clean up some of the joints, but they do all have continuity. Both crossovers demonstrate the same symptoms too.

Kiwiaudio

Gardenstater wrote: »

Yeah so if you jumper out the capacitor, then you'll get a resistance reading.

And yes, temporarily jumping the cap works. I get 1.5 ohms actual at the input cup with both tweeters connected.

So you dont see a problem then ?

Gardenstater

Kiwiaudio wrote: »

Gardenstater wrote: »

Yeah so if you jumper out the capacitor, then you'll get a resistance reading.

And yes, temporarily jumping the cap works. I get 1.5 ohms actual at the input cup with both tweeters connected.

So you dont see a problem then ?

I would say off hand that it seems a little low, even though the tweeters are in parallel but I do not know what the DCR of each tweeter measures (check them) or what the DCR of the air coil inductor is (check that too).

Kiwiaudio

Tweeters listed at 6 ohm actually measure at 4.7
Air coil measured at .5 ohms attached to the board.

Gardenstater

6 ohms nom. impedance makes sense because I found that is the rating of the overall speaker system. DCR is always less than nominal impedance, so 4.7 seems reasonable. If you do the math with the circuit you drew and the values you gave that would give a very low resistance of only 1.25 Ohms, pretty close to your 1.5 Ohm measurement.

VR3

I may have missed it but what exactly is the issue you are having. Do they sound bad, don't work, etc

Gardenstater

Are you sure you have drawn the circuit correctly? Are you sure the 0.5 ohm resistor isn't in series with the air core inductor? That would give 1.52 Ohms total circuit DCR.

PS: You have to disconnect the negatives at the tweeters to measure the DCR of that inductor on the board.

Kiwiaudio

I may have missed it but what exactly is the issue you are having. Do they sound bad, don't work, etc

I wanted to do a mild refresh on the crossovers, and after replacing the caps and resistors, i tested my work with a multimeter and found the open HI circuit with speaker drivers connected as they would be in the cabinet. Ive never seen this before and figured i must have messed up somewhere. Ive always seen a load at the speaker input cups, and indeed if i jumpered the Hi and Lo cups together as most people will with this speaker, it will present about a 5 ohm load from the LO circuit.
I have not put the speakers back together to try yet - im half expecting to get nothing out of the tweeters.
These were so simple, and i was only replacing with like values, that i didnt test the factory setup beforehand. Now i wish i had an original crossover to compare.

Are you sure you have drawn the circuit correctly? Are you sure the 0.5 ohm resistor isn't in series with the air core inductor? That would give 1.52 Ohms total circuit DCR.

Ive traced it several times and im pretty sure my schematic is correct. You should be able to see it on this pic. Black arrows depict the air core inductor

Gardenstater

Well OK I can't tell for sure without arrows for the other components. But anyways there's no reason to think that it isn't going to work. The capacitor doesn't pass DC current which is why you had to jumper it out to get a DCR reading on the tweeter circuit. The capacitor will have some resistance in playing signals because of ESR aka effective series resistance. Maybe those tweeters needed a low impedance circuit in order to get the right voicing vs. the 4 midwoofers.