From my link in post #22, the Trebax 100 optimistically extends to 20,000 Hz (see attachment).
As for relative phase, this can also be determined by the relative positions (depths) of the sound emitting centres of the drivers and not just by the crossover components. Best to phase by ear as you have suggested.
P.S. I would leave the crossover as standard. I can't help but feel you are overthinking things in regard to the addition of the dome tweeter.
I would simply roll the dome in gradually above, say, 12,000 Hz, but would not go as far as to roll off the Trebax, which seems to be rolling off mechanically on its own accord.
As for relative phase, this can also be determined by the relative positions (depths) of the sound emitting centres of the drivers and not just by the crossover components. Best to phase by ear as you have suggested.
P.S. I would leave the crossover as standard. I can't help but feel you are overthinking things in regard to the addition of the dome tweeter.
I would simply roll the dome in gradually above, say, 12,000 Hz, but would not go as far as to roll off the Trebax, which seems to be rolling off mechanically on its own accord.
Attachments
Agreed.
I found a .25mH inductor so I'll put that in parallel with the 10 ohm resistor and dome tweeter and see how it sounds.
Won't need to low pass the trebax for sure as the link you posted in post 3 has the trebax going to 16kHz with it being 8dB down at 20kHz.
Now for the music out when these drivers were made, that would have been fine as there wasn't much music content above 15kHz anyways.
A bonus is if I don't like the sound with the inductor, I can just disconnect it as the .47uF cap is what I'm currently using.
I found a .25mH inductor so I'll put that in parallel with the 10 ohm resistor and dome tweeter and see how it sounds.
Won't need to low pass the trebax for sure as the link you posted in post 3 has the trebax going to 16kHz with it being 8dB down at 20kHz.
Now for the music out when these drivers were made, that would have been fine as there wasn't much music content above 15kHz anyways.
A bonus is if I don't like the sound with the inductor, I can just disconnect it as the .47uF cap is what I'm currently using.
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Yes, the link in post #3 tells all about the Trebax. In post #41, I attached the info on the Trebax 100 which appears to be a different unit.
In those days, FM radio was a popular music source. Since FM only extended to 15 kHz, there was little point in the tweeter extending further.
EDIT: I understand your inductor placement. I had to put the capacitor in place!
In those days, FM radio was a popular music source. Since FM only extended to 15 kHz, there was little point in the tweeter extending further.
EDIT: I understand your inductor placement. I had to put the capacitor in place!
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Oh ok think I do have the Trebax 100, however it looks just like the one in the link in post 3. Checking the dimensions of the horn in both links they appear to be the same driver or at least the horn is the same.
Either way the dome tweeter reproduces what the trebax is lacking so I'm satisfied.
Now when I get the tube amp restored and sounding its best I'll try it on the speaker with and without the dome tweeter just to see if the dome is still needed as sometimes some speakers perform better on tubes than solid state.
Once had a low cost pair of two way speakers that used just a single capacitor for the crossover. They sounded great on a tube amp, but on a solid state amp it was as though someone put an l-pad on the tweeter and turned it down.
Either way the dome tweeter reproduces what the trebax is lacking so I'm satisfied.
Now when I get the tube amp restored and sounding its best I'll try it on the speaker with and without the dome tweeter just to see if the dome is still needed as sometimes some speakers perform better on tubes than solid state.
Once had a low cost pair of two way speakers that used just a single capacitor for the crossover. They sounded great on a tube amp, but on a solid state amp it was as though someone put an l-pad on the tweeter and turned it down.
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I found a few year old Wima .47uF cap in my stash and installed that along with the inductor. The dome tweeter seems to sound great and I can easily tell when I cover its face as the top end of the treble goes away.
Overall I am well pleased with the sound.
Overall I am well pleased with the sound.
I agree.
I at least won't tweak until I get the Heathkit amp, and I'll only tweak then if it is needed. When I tweak a speaker I prefer doing it connected to the amp it will be used with. That way I get the best sound.
The dome tweeter circuit is connected to the input of the crossover.
I at least won't tweak until I get the Heathkit amp, and I'll only tweak then if it is needed. When I tweak a speaker I prefer doing it connected to the amp it will be used with. That way I get the best sound.
The dome tweeter circuit is connected to the input of the crossover.
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I was in an oldies mood today so when I could listen to the speaker I played some oldies.
The speaker sounds great with modern music, but sounds real good with oldies music which I kind of expected given when the drivers were made.
EDIT:
Now if I do happen to run across another pair of the RCA woofers, I'll have two proper cabinets made and have a nice set of open back stereo speakers.
The speaker sounds great with modern music, but sounds real good with oldies music which I kind of expected given when the drivers were made.
EDIT:
Now if I do happen to run across another pair of the RCA woofers, I'll have two proper cabinets made and have a nice set of open back stereo speakers.
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Should I get a small box to put the trebax in with the dome tweeter above the trebax or should I leave it as is?
I went ahead and put them in a small box. I used double sided tape to secure the boxes to each other then I used two screws, washers and nuts to make it more secure. The dome tweeter is heard a little easier being above the trebax instead of between the midax and trebax.
One further question.
The copper screen material that I used to cover the woofers is made up of thin wires that are spaced 1/16" (1.57mm) from each other vertically and horizontally.
Will that attenuate the sound coming from the two RCA woofers?
If so can I simply add the same material over the other drivers and achieve the same attenuation?
One benefit of the copper screen material if it works is it will help keep dust out of the midax, trebax and dome tweeter.
The more I listen to this speaker the more I like it. Can't wait to hear it on a tube amp.
I like how clean the sound is. The midax is real clean sounding especially for vocals.
One further question.
The copper screen material that I used to cover the woofers is made up of thin wires that are spaced 1/16" (1.57mm) from each other vertically and horizontally.
Will that attenuate the sound coming from the two RCA woofers?
If so can I simply add the same material over the other drivers and achieve the same attenuation?
One benefit of the copper screen material if it works is it will help keep dust out of the midax, trebax and dome tweeter.
The more I listen to this speaker the more I like it. Can't wait to hear it on a tube amp.
I like how clean the sound is. The midax is real clean sounding especially for vocals.
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Metal mesh for woofer grilles should be sufficiently open (say about 60% open in area) to not impede air flow. You could work out the open area of your screen material using your wire thickness and spacing dimensions. If using the screen material over the woofers currently introduces no problems, then I wouldn't worry.
Your copper screen may cause diffraction and loss of high frequency energy when placed over the high frequency drivers.
By simply holding the mesh in front of the individual HF drivers and listening for any difference it makes, you can judge for yourself how significant the loss introduced by the mesh is.
Your copper screen may cause diffraction and loss of high frequency energy when placed over the high frequency drivers.
By simply holding the mesh in front of the individual HF drivers and listening for any difference it makes, you can judge for yourself how significant the loss introduced by the mesh is.
Oh ok.
Not sure how thick the wire is nor do I have a way to measure it accurately I don't think.
I'll post a picture of the mesh in a bit.
EDIT:
I took about a 2" X 3" piece of the screen and blew on my hand with the screen between my hand and mouth and with it removed. The air hitting my hand felt stronger without the screen and with the screen in place I could feel a slight bit of air hitting my face.
So I may just remove the screen.
What kind of material would be recommended to use that will protect the woofers should something hit it accidentally?
Not sure how thick the wire is nor do I have a way to measure it accurately I don't think.
I'll post a picture of the mesh in a bit.
EDIT:
I took about a 2" X 3" piece of the screen and blew on my hand with the screen between my hand and mouth and with it removed. The air hitting my hand felt stronger without the screen and with the screen in place I could feel a slight bit of air hitting my face.
So I may just remove the screen.
What kind of material would be recommended to use that will protect the woofers should something hit it accidentally?
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There are commercial expanded metal mesh speaker grille sheets, but they can be fairly pricey.
https://www.expandedmetalcompany.com/applications/automotive/speaker-grilles
Or you can get individual 12" loudspeaker grilles from the likes of Amazon.
https://www.expandedmetalcompany.com/applications/automotive/speaker-grilles
Or you can get individual 12" loudspeaker grilles from the likes of Amazon.
Cool.
I may look into that.
With the grill on it seemed like the midax and trebax seemed slightly louder.
I removed the grill and the sound is more balanced.
What I might do is look for one of those grills that doesn't use the speaker mounting screws to hold and instead uses four tabs that are screwed to the box as I really don't want to remove the woofers just to mount grills as that won't be very easy.
Perhaps something like this.
https://www.amazon.com/Tongze-Speaker-Grill-Cover-Mesh-Waffle/dp/B0C173DJC5/ref=sr_1_8?
I may look into that.
With the grill on it seemed like the midax and trebax seemed slightly louder.
I removed the grill and the sound is more balanced.
What I might do is look for one of those grills that doesn't use the speaker mounting screws to hold and instead uses four tabs that are screwed to the box as I really don't want to remove the woofers just to mount grills as that won't be very easy.
Perhaps something like this.
https://www.amazon.com/Tongze-Speaker-Grill-Cover-Mesh-Waffle/dp/B0C173DJC5/ref=sr_1_8?
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So I decided to put lipstick on a pig and paint the cardboard box with some satin black paint I have at work. I got the small box, large box top and large box front painted. Just need to add a second coat to the large box front.
It doesn't look very good, but it looks tons better than just the bare cardboard did. May try to take a picture Monday.
Cardboard sure does absorb paint......................
Seems like satin black was what was used on the midax as I painted the front edge and side of the horn where the mounting holes are and it matched the rest of the paint perfectly.
Thought I would have to paint the inside of the horn as well given it had a few spots that look like my Altec 811B horns which do need a repaint, however I tried cleaning it first with a cleaning wipe and it was just dirt and such so I did not need to repaint that.
I also found some ring terminals at work that fit the driver connecting screws on the midax so that I no longer need the wires just stuck in the holes where banana plugs would go. The smooth finish midax has ring terminals on it which is how I figured out it was possible to remove those screws and use ring terminals without damaging the driver.
I may try a low pass on the trebax to see if it improves the sound further as it sounds like the trebax is reproducing some of what the dome tweeter is reproducing. I'll have to move the l-pad from inside the crossover to the trebax terminals though, but that will be fine. The high pass I'll stick in the box the trebax and dome are in.
Usually that's how it goes with me. I try something and over time I either think it sounds good as is or I notice things that aren't right which a brief listen cannot reveal.
EDIT:
I need to order some resistors for another speaker project so I'll just add a cap and inductor to the order. I'd need a .234mH inductor and a .521uF capacitor.
It doesn't look very good, but it looks tons better than just the bare cardboard did. May try to take a picture Monday.
Cardboard sure does absorb paint......................
Seems like satin black was what was used on the midax as I painted the front edge and side of the horn where the mounting holes are and it matched the rest of the paint perfectly.
Thought I would have to paint the inside of the horn as well given it had a few spots that look like my Altec 811B horns which do need a repaint, however I tried cleaning it first with a cleaning wipe and it was just dirt and such so I did not need to repaint that.
I also found some ring terminals at work that fit the driver connecting screws on the midax so that I no longer need the wires just stuck in the holes where banana plugs would go. The smooth finish midax has ring terminals on it which is how I figured out it was possible to remove those screws and use ring terminals without damaging the driver.
I may try a low pass on the trebax to see if it improves the sound further as it sounds like the trebax is reproducing some of what the dome tweeter is reproducing. I'll have to move the l-pad from inside the crossover to the trebax terminals though, but that will be fine. The high pass I'll stick in the box the trebax and dome are in.
Usually that's how it goes with me. I try something and over time I either think it sounds good as is or I notice things that aren't right which a brief listen cannot reveal.
EDIT:
I need to order some resistors for another speaker project so I'll just add a cap and inductor to the order. I'd need a .234mH inductor and a .521uF capacitor.
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Didn't want to buy parts not knowing if it will make the speaker sound better so I found a larger inductor and unwound some until I got the correct inductance. All I need is to find the capacitor. Closest I can easily get with just two caps is using a .47 uF and a .047 uF in parallel for .517uF. Given a 5% tolerance of most regular film caps the .521uF cap can be anywhere between .495 uF to .547 uF.
Given a typical 5% tolerance of a .47uF and .047uF cap the cap combination can be anywhere between .491uF to .543uF.
So I believe a .47uF and .047uF cap in parallel will work just fine and also a .5uF cap . No need in trying to make a .521uF cap which would have required a .47uF cap in parallel with 5 .01uF caps which would have actually had more variance in tolerance.
Given a typical 5% tolerance of a .47uF and .047uF cap the cap combination can be anywhere between .491uF to .543uF.
So I believe a .47uF and .047uF cap in parallel will work just fine and also a .5uF cap . No need in trying to make a .521uF cap which would have required a .47uF cap in parallel with 5 .01uF caps which would have actually had more variance in tolerance.
I wouldn't sweat over it.
A variation of up to plus or minus 10% of the theoretical value is acceptable in an application such as yours.
A variation of up to plus or minus 10% of the theoretical value is acceptable in an application such as yours.
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Closest I have is a 1uF 10% Auricap that reads 1.096uF and a 1uF orange drop that reads 1.065uF for a total capacitance of .54uF. That would be within the 5% tolerance range of the .521uF cap value I needed so I'll try that.
Now if I can hear no audible difference, I'll remove the low pass on the trebax as I'll then know it isn't needed.
Now if I can hear no audible difference, I'll remove the low pass on the trebax as I'll then know it isn't needed.
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