Usually you can find right and left inputs on the line|microphone input on a sound card. On my laptop its on a minijack connector and you choose the level when you plug the jack via a popup windows on the system.
The negative speaker is connected to the negative pin of the headphone out.
I've made a small jig using two female RCA connectors where I connect a standard RCA/minijack connector for line input.
See attachment.
Attachments
I think the schema show everything :
Headphone Output right -> Rsense
Mic input left -> Rsense
Mic input right -> + speaker
Connect :
- ground Headphone output
- ground Mic input
- speaker negative pin
All together
Yes you need Rsense, a 100 ohms resistor 1/4 W 1%, as shown in the schema.
Headphone Output right -> Rsense
Mic input left -> Rsense
Mic input right -> + speaker
Connect :
- ground Headphone output
- ground Mic input
- speaker negative pin
All together
Yes you need Rsense, a 100 ohms resistor 1/4 W 1%, as shown in the schema.
Attachments
Last edited:
Question about damping
If someone could weigh-in, I had a question about the foam and stuffing I used. I'm going to be taking out the drivers tomorrow to finish my speakers so I hope someone can answer by then. I used 1.5" acoustic eggcrate foam to line all walls except for the baffle and about .75 lb of acousti fill per speaker. Stuffed heavily top and bottom and a handful behind the two woofers. Troel's design called for 10mm foam, but I didn't notice until after I had ordered the eggcrate. Is the foam I used okay or is the speaker over damped or something? Also, does this sound like the right amount of stuffing? Or maybe I should remove the fill since I used such a thick foam?
Thanks
If someone could weigh-in, I had a question about the foam and stuffing I used. I'm going to be taking out the drivers tomorrow to finish my speakers so I hope someone can answer by then. I used 1.5" acoustic eggcrate foam to line all walls except for the baffle and about .75 lb of acousti fill per speaker. Stuffed heavily top and bottom and a handful behind the two woofers. Troel's design called for 10mm foam, but I didn't notice until after I had ordered the eggcrate. Is the foam I used okay or is the speaker over damped or something? Also, does this sound like the right amount of stuffing? Or maybe I should remove the fill since I used such a thick foam?
Thanks
Hi Satx,
I'm going to buy few resistors today, maybe il will install them tomorow.
I wil write the review after I will have the correct tweeter level.
I'm going to try 1.2 and 15 ohms, 1.5 and 15 ohms for the L-pad value.
One of this combinaison should be OK producing ~0.5 and ~1 more db of attenuation.
Concerning the stuffing, i've done as recommended on Troels web site:
bitumen pad + 10 mm felt on every side except top and floor side and front panel.
Three pieces of sonofil (dacron) on back and top, one piece behind each woofer.
I dont think eggcrate foam is the right product for stuffing.
Also measuring the impedance of the speaker can show if theres is bad resonance in the box.
FIY Modifying the stuffing can modify the box tuning
I'm going to buy few resistors today, maybe il will install them tomorow.
I wil write the review after I will have the correct tweeter level.
I'm going to try 1.2 and 15 ohms, 1.5 and 15 ohms for the L-pad value.
One of this combinaison should be OK producing ~0.5 and ~1 more db of attenuation.
Concerning the stuffing, i've done as recommended on Troels web site:
bitumen pad + 10 mm felt on every side except top and floor side and front panel.
Three pieces of sonofil (dacron) on back and top, one piece behind each woofer.
I dont think eggcrate foam is the right product for stuffing.
Also measuring the impedance of the speaker can show if theres is bad resonance in the box.
FIY Modifying the stuffing can modify the box tuning
Last edited:
Pascal,
Are you changing R1051 and R1061? Is that how you are attenuating the tweeter?
On the stuffing, I don't even know where to get the felt, but he does say 10mm felt or foam. I also don't know where to get foam that thin, I think the thinnest I found was about 20mm. It is acoustical foam, don't know if thats any different than normal eggcrate. I have seen seen eggcrate used in subwoofers, But I wonder if it kills the midrange some. I know it can change the tuning because it gives the impression of a larger box, I still think it is tuned between 40 and 42hz; it's at 42 just based on net volume.
Are you changing R1051 and R1061? Is that how you are attenuating the tweeter?
On the stuffing, I don't even know where to get the felt, but he does say 10mm felt or foam. I also don't know where to get foam that thin, I think the thinnest I found was about 20mm. It is acoustical foam, don't know if thats any different than normal eggcrate. I have seen seen eggcrate used in subwoofers, But I wonder if it kills the midrange some. I know it can change the tuning because it gives the impression of a larger box, I still think it is tuned between 40 and 42hz; it's at 42 just based on net volume.
Too much stuffing might "kill" the midrange and make the speaker sound dull. In my Ellams I originally had too much sonofil behind the woofers and it made the sound suppressed and dull. I took half sheet out and now the midrange is clear and present. You could try taking some stuffing out, but remember that your speakers are still running in. IMO you should let them play for couple of weeks, and don't be afraid to crank up the volume every now and then. After the woofers have broke in, the tonal balance will be different. That way you also adapt to the sound and start to recognize their character.
Hi,
I'm using an online calculator to determine port length and the numbers that it is providing are different from the numbers that Troels specifies. Troels says that for a 2.68" id port to cut it to 2.36" for a port tuning of 45hz for the 40L Nomex build. The calculator calls for a 2.68 id port to be cut to 3.4" length for 45hz in 40L. What gives? I'm am actually using a 2.5" port and have tried a couple of different lengths for different tuning, but now I'm not sure if I have it tuned to what I thought. I currently have It cut to 4" for a presumed tuning of about 40hz.
Can anyone shed any light here.
Thanks
I'm using an online calculator to determine port length and the numbers that it is providing are different from the numbers that Troels specifies. Troels says that for a 2.68" id port to cut it to 2.36" for a port tuning of 45hz for the 40L Nomex build. The calculator calls for a 2.68 id port to be cut to 3.4" length for 45hz in 40L. What gives? I'm am actually using a 2.5" port and have tried a couple of different lengths for different tuning, but now I'm not sure if I have it tuned to what I thought. I currently have It cut to 4" for a presumed tuning of about 40hz.
Can anyone shed any light here.
Thanks
According to my calculations:
34l cab, 2.5" port dia, Fb=40Hz -> 3.45" port length
40l cab, 2.5" port dia, Fb=40Hz -> 2.75" port length
I used speakerboxdesigner worksheets and multiplied the port length with 0.7 (I do not know where this factor is from, but Troels uses it when determining port lengths).
34l cab, 2.5" port dia, Fb=40Hz -> 3.45" port length
40l cab, 2.5" port dia, Fb=40Hz -> 2.75" port length
I used speakerboxdesigner worksheets and multiplied the port length with 0.7 (I do not know where this factor is from, but Troels uses it when determining port lengths).
The actual port length depends on how it is flared. Do not spend too much time on deciding which port length and which exact tuning point you want to have. Think of them as suggestions and basis for tuning by your ears (and possibly with impedance and/or FR plots) to get your preferred sound. If it suits you, it doesn't matter if the actual tuning is 40Hz or 45Hz. If the bass output is too dominant and heavy, lowering the tuning will help in most of the cases. If it is OK by your means of evalution, then You don't have to any changes. And have patience with the running in period 
The tonal balance will have changes within couple of weeks.
The tonal balance will have changes within couple of weeks.- Status
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