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

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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")

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.
 
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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
 
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.
 
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Looks like your tweeter network touches the ground (between 3.3 ohm and 3.3uF)
 

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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.
 
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:) :) :)

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.
 
hello jay,

yes that's a good option.

so i did it, nowhere the sounds drops away. so i guess i must be alright.

in the beginning i hadn't connect the tweetercoil to the minus, and the tweeter played a lot louder, (maybe because off the presence of more low to the tweeter)

i have mailed troels and he answered a couple of times, he told me that it could be that we are too used to listen to too much highs. and he has a point on that. my fonken fe127 have to much highs.

maybe the speaker has to set in, cause i find them quite dull at the moment; i will play them for a few days;
any tips are welcome

thanks again
 
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Joined 2005
tweeter could be sticking
happened to me once
it played, but very low
I loosened faceplate
realligned it
and all was well again

I checked by pushing the surround/coil connection gently, by using a soft pointed toothstick

to check tweeter, maybe just put a small cap in series with it
and play music

is it just one tweeter, or both having same problem
if tweeters are sound and functional, check xo layout
might be a simple error, somewhere
 
a sticking tweeter, mm, that's interesting, never heard of it. but i think that that is not the issue. i wonder if there is an issue, except my own ears.

the highs are there, the lows are there, but i find them lacking "very high mids", it sound like there is a veil over it; nothing seems very clear, male voices sound dull, and i don't expect a male voice of 100hz to be dull. maybe i need to look into the bass part of the filter.

i know it is difficult when somebody is describing the sound of speaker, but is does sound dull. i have a bob brines fostex 167, and that doesn't has to much high's either, still it plays much more bright detailled in the midrange.
i'll investigate further.

i don't have a frequency analyzer, otherwise i would use it.

i have to say that the sound doesn't sound compressed at all, that's great;
 
i think i found a clue.

i was looking at the frequency response and saw that the highs are bit under the lows.
at 300hz the bass goes to 86db, at 6000hz it is 82db; the highs are bit lower then the lows, and yes the most commercial speakers do a little lift (some a serieus lift) of the highs;

at the same page at troels website, there is a norwegian guy who has build them too, and (from google translate) i can make up that he put's a 1.8 ohm with the woofer to muffle it a bit. I guess that would do the trick.

so some questions about it:
1)where to place the resistor ? and how much watt would it have to bear.
2)can i not lift the tweeter a bit, so that i don't loose any efficency ?

thanks guys
greetz
 
No, don't put a resistor on the WOOFER, instead reduce the resistors on the tweeter.

I have built the enclosure (mine is not ported yet), measured the tweeter, and simulated the crossover. I might be able to take a look at it when I'm home either at night or on the weekend and suggest some values and which resistor to adjust...
 
Please try this:

Connect a second resistor in parallel with your 3.6 (suposed to be 3.3) ohm resistor "R1051".

For the parallel resistor you are adding use a value between 1.5 - 4 Ohms.

EDIT: Also, until I can check the simulation at home, I'm not sure, but you may want to replace your 5.0 Ohm (supposed to be 4.7 Ohm) resistor with one that is 4.7 ohms or less.

EDIT II: since we know you want more tweet not less, you don't have to remove any resistors which are already in place unless you can't find the right size second resistor to put in parallel with it to get the level you want... Here is a web page you can use to do the simple calculation of parallel resistors for you: http://www.1728.com/resistrs.htm
 
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thanks a lot critofur,

i was planning putting some resistors parrale, but i got only big or very small values, not really the desired 6-16 ohm at 10 watt, but i might give it a try
thanks for the website

i don't know much about filter design, but i wonder what it would take to add 2db to the tweeter;
 
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Phew-- I don't know whats going on here. I have that vifa TW, and I am used to a little more sizzle, but over the years I come to realize that often what i hear is peaking of one sort or another. That vifa can have highs! What i do have is recommedations about how to set up the box, so the wiring is not so maddening.

I believe in -No terminal strips.
- A ground wire permanently attached to the back of the box. Connections: at the bottom of the box, woofer (-) at the top Tw (-) in the middle: binding post-black
Then: woofer inductor secured to the box back panel, (+) into it, ?red? wire out.

Now a whole lot of things you won't tweak are out of the way, certified, and ready to go. What remains can be put on some board, small, which will slide easily out of a driver hole.
A black wire goes to it, a plus, and a (Ind) + wire. The wires need not be massive!!
this makes everything troublesome, and in terms of series resistance, is nothing, like nothing, of consequence. Likewise the resistors can be quite minimal (I have lots of 1W resistors around, for paralleling). when you like your design, you can go with 10W types.
But really, for a tweeter, 3-W is fine (life 3 10r's together. of 1W each, to get 3.33 ohm)

A nice slim (+) wire can go to the TW (+) a regular like 18-19 Ga wire goes to the woofer. (I don't know the metric sizes, here) IN SHORT LENGTHS, the wire power dissipation is, like, nothing. Really! All this is to clarify the setup, so that you can actually SEE where the mistakes are. (I have made plenty of mistakes. Mostly when there is a PCB involved, rather than where point-to-point wiring is involved.
I have those sandwich cone peerless-en that Troels likes (the original 850-488 or near thereto) so someday, I'd like to try this project! As mentioned, I find the XT25G30's just fine, and smooth.

Go for it! Doug
 
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Joined 2005
i don't know much about filter design, but i wonder what it would take to add 2db to the tweeter;

it appears there are two resistors in series with the tweeter
one before the actual xo, and one after

the only one you should touch is the one before the xo...R1011
first move, try to paralel it with another resistor of equal size
then it will have half its original value
and lets hear what happens

or you could try to simply short it with a wire
but please make sure its the right resistor(R1011)
 
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