troels design: peerless hds ppb 830860 + vifa xt 25tg 30-04 : Low volume tweeter

[then_dude]

hello everybody,

i helped a friend of mine building a speaker. We choose the troels gravesen design :"peerless hds ppb 830860 + vifa xt 25tg 30-04" because of the low cost and small size.

Peerless HDS PPB 830860


my friend has done the woodwork, and we soldered the filter.
when we connect the drivers: the tweeters plays at the volume of a headphone, the woofer is going strong.

i have connected a fostex fe127 to the woofer and then to the tweeter connection and it is clear that it is a filter issue.

i have looked at the scheme and everthing seems in place, and i have measured a few parts and they seem okee (the resistors), the caps are only measurable if i disconnect them, but my friend has glued everything, so that is not a desirable option. I have taken a picture of the filter.

i wonder if anyone could comment on this.
i will also email troels, so that he can shed his light on this issue too, if he finds the time.

thanks in advance

(ps i'm trying to find out how a picture is put online")

[PeteMcK]

check your wiring, then check it again...
also check the values of resistors in the tweeter circuit, what are the colours on them?

[then_dude]

the resistors have no color on them, it is written on them, but i measured them, and they were okee, (at least within 10% tolerance): the 4.7 was 5; and the 3.3 was 3.6

we have both looked at the wires for many times, we don't see any mistake, still it is 50% change that there is.
thanks

[andy2]

If you could take a picture of the tweeter xover so we can take a look.
Also Troels tends to voice his speakers pretty laid back so his treble level a bit lower than other speakers you've heard before.
There is L1031 to ground so make sure it's not shorted.

[Jay]

Looks like your tweeter network touches the ground (between 3.3 ohm and 3.3uF)

[then_dude]

thanks jay,

but it is the picture that suggest this , in reality it is not touching.

so do you think the wiring is okay ? if this is the case, some parts must be off specs, and then i guess i need to unsolder and mesure every part.

[critofur]

Could you measure the the impedance of your speaker and post a picture of that?

[Jay]

Simply bypass each components (R/C) in the tweeter network one by one using wire to see which one is malfunctioning.

[then_dude]

hello,

i have unsolderderd a few connections and measured every component and they are all in spec. exept the coil, that has an RDC of 0.30 instead of the 0.23 which it mentioned on the label. still, i don't think that that could cause such an enorm drop in volume.
i'm clueless. and i have it with the two speakers, so the two filters act the same. (so i guess the both parts are oke, and the wiring is okee...) strange.

[Jay]

1) Check if your tweeter is not broken: Put the woofer in the tweeter connection. If treble comes out loud enough from the woofer then the tweeter is broken. If not then continue...

2) Connect tweeter negative to ground and tweeter positive to several points:

a) between 8.2uF and 4.7 ohm (bypassing the 4.7 ohm). If normal then the 4.7 is broken. If not normal then continue...

b) between 3.3uF and 8.2uF (bypassing the 8.2uF and 4.7 ohm). If normal then the 8.2 is broken. If not normal then continue...

Well, no need to go further. This is simply the simplest troubleshooting in the world. What you need is simply a procedure to FOLLOW. That's how we engineers work.