Slicemaster:
The people who have taken the time to respond are trying to help you, not engage in an anti-Blaupunkt conspiracy, as you seem to be saying. It takes a certain amount of effort to make and upload a graph. The response from you should be something besides accusations. Nobody is getting paid for this, you know.
If you must know, there are certain combinations of Qts, enclosure volume and vent tuning, if any, that are considered optimum. According to the database of WinISD, which is normally pretty accurate, the Blaupunkt PCWG 120 has a Qts of .45, and a Vas of 4.3 cubic feet. Normally, for a vented box, the recommended box size would be between 3.5 and 6 cubic feet-considerably larger than the 2 cubic feet you mentioned.
Fact is, for this Blaupunkt and a 2 cubic foot box, most speaker designers would consider a SEALED enclosure the ideal way to go. You are kind of stretching it a little-but not terribly-by going vented. One speaker could be used for both a sealed and a vented enclosure, but the sealed enclosure will be smaller and have not so deep a bass output.
Every woofer in every box will have a cutoff frequency, beneath which the loudspeaker plays less and less loudly the lower you go. If you compare the PCwg120 and the Peerless, you see that at 30 Hz, the Blaupunkt is about 7 dB down from it's normal playing level. The Peerless is about 3 dB down.
If my amplifier is putting out 100 watts, when I hit 30 Hz I would have to feed the Peerless 200 watts to bring it up to normal playing level. I would have to feed the Blaupunkt over 500 watts to do the same thing.
On the other hand, at 37 Hz, the Blaupunkt will be at the same volume level that the Peerless is at 30 Hz. You got that?
Yes, you can make the vent longer. If it hits the back of the box, you can go to Home Depot or some place and get an elbow that will allow the vent to fit into the enclosure. To tune the box to 25 Hz, the 3" diameter vent should be 12 3/4" long. Such a vent would work well in your box, by the way.
I'm going to try it one more time. Following is a graph of the Blaupunkt in a 2 cubic foot box tuned to 30 Hz. Note the position of the response at 30 Hz in relationship to the green line, which is the point at which the response is 3 dB down. Now look at the Peerless, which I showed earlier. The Peerless puts out more at 30 Hz.
To briefly summarize, the Blaupunkt will work okay in a 2 cubic foot enclosure vented to 30 Hz or 25 Hz. The Peerless will work a little better, but if your heart is set on the Blaupunkt, it won't be grossly mismatched in the 2 cubic foot vented enclosure.
The people who have taken the time to respond are trying to help you, not engage in an anti-Blaupunkt conspiracy, as you seem to be saying. It takes a certain amount of effort to make and upload a graph. The response from you should be something besides accusations. Nobody is getting paid for this, you know.
If you must know, there are certain combinations of Qts, enclosure volume and vent tuning, if any, that are considered optimum. According to the database of WinISD, which is normally pretty accurate, the Blaupunkt PCWG 120 has a Qts of .45, and a Vas of 4.3 cubic feet. Normally, for a vented box, the recommended box size would be between 3.5 and 6 cubic feet-considerably larger than the 2 cubic feet you mentioned.
Fact is, for this Blaupunkt and a 2 cubic foot box, most speaker designers would consider a SEALED enclosure the ideal way to go. You are kind of stretching it a little-but not terribly-by going vented. One speaker could be used for both a sealed and a vented enclosure, but the sealed enclosure will be smaller and have not so deep a bass output.
Every woofer in every box will have a cutoff frequency, beneath which the loudspeaker plays less and less loudly the lower you go. If you compare the PCwg120 and the Peerless, you see that at 30 Hz, the Blaupunkt is about 7 dB down from it's normal playing level. The Peerless is about 3 dB down.
If my amplifier is putting out 100 watts, when I hit 30 Hz I would have to feed the Peerless 200 watts to bring it up to normal playing level. I would have to feed the Blaupunkt over 500 watts to do the same thing.
On the other hand, at 37 Hz, the Blaupunkt will be at the same volume level that the Peerless is at 30 Hz. You got that?
Yes, you can make the vent longer. If it hits the back of the box, you can go to Home Depot or some place and get an elbow that will allow the vent to fit into the enclosure. To tune the box to 25 Hz, the 3" diameter vent should be 12 3/4" long. Such a vent would work well in your box, by the way.
I'm going to try it one more time. Following is a graph of the Blaupunkt in a 2 cubic foot box tuned to 30 Hz. Note the position of the response at 30 Hz in relationship to the green line, which is the point at which the response is 3 dB down. Now look at the Peerless, which I showed earlier. The Peerless puts out more at 30 Hz.
To briefly summarize, the Blaupunkt will work okay in a 2 cubic foot enclosure vented to 30 Hz or 25 Hz. The Peerless will work a little better, but if your heart is set on the Blaupunkt, it won't be grossly mismatched in the 2 cubic foot vented enclosure.
Attachments
thank you for all your help...
espechialy kelticwizard..... tank you so much!
i am sorry if i gave you guys the wrong idea about what i was trying to say....
the fact is that i am a little tence about this project ,it being my first ever....
i am relly tankful for you guys here who took the time to help me out....
i am striving to lern more and i hope i did not give you guys the wrong idea about me.
it's just that i want to make an informed desicition about what components i choose and why....
i again that you all for the help and time....
aditional feed back would be nice but never required....
thank you, kelticwizard for helping me get my facts straight....
as you guys can tell i am relly new to the diy cercit.....
this is my first time working indepth with speakers and enclosures. and i am hoping to upgraid the driver to a better quality one when i have the money.....thanks to your advice....
thank you all...
espechialy kelticwizard..... tank you so much!
i am sorry if i gave you guys the wrong idea about what i was trying to say....
the fact is that i am a little tence about this project ,it being my first ever....
i am relly tankful for you guys here who took the time to help me out....
i am striving to lern more and i hope i did not give you guys the wrong idea about me.
it's just that i want to make an informed desicition about what components i choose and why....
i again that you all for the help and time....
aditional feed back would be nice but never required....
thank you, kelticwizard for helping me get my facts straight....
as you guys can tell i am relly new to the diy cercit.....
this is my first time working indepth with speakers and enclosures. and i am hoping to upgraid the driver to a better quality one when i have the money.....thanks to your advice....
thank you all...
one last q....
does it matter how close to the enclosure wall the port comes to?
in other words can the port be 2in away form the back of the box.... if it does matter what type of elbo should i get?
does it matter whitch way the port end is pointing when i put the elbo on......
thanks for all the help....
this is my final q....
does it matter how close to the enclosure wall the port comes to?
in other words can the port be 2in away form the back of the box.... if it does matter what type of elbo should i get?
does it matter whitch way the port end is pointing when i put the elbo on......
thanks for all the help....
this is my final q....
Slicemaster:
No need to make that your last question. This forum is all about people asking questions. I ask questions from others who know more about certain audio subjects than myself.
Just downloaded the manual for the Blaupunkt 120. It's a better woofer than I thought. It probably is your best choice for your subwoofer after all. Will explain in another post, gotta run for now.
No need to make that your last question. This forum is all about people asking questions. I ask questions from others who know more about certain audio subjects than myself.
Just downloaded the manual for the Blaupunkt 120. It's a better woofer than I thought. It probably is your best choice for your subwoofer after all. Will explain in another post, gotta run for now.
Slicemaster:
Before I can absolutely say that the Blaupunkt is the best speaker for the job, I have to check one thing with their technical department. The Xmax-the back and forth movement of the cone-is listed as .25 inch. For many speaker manufacturers, that means .25" from midpoint to front, then .25" from midpoint to back. However, some speaker manufacturers measure all the way from the back of the speaker's travel to the front. That is quite a difference. I am pretty sure that Blaupunkt measures from center to front, but I want to check. I will do so Monday.
One of the reasons I liked the Peerless woofer so much was that it had a symmetric magnet system. There is more magnet behind the voice coil than in front, in most speakers. As a result, near the tuning frequency in a vented box, most speakers experience "suck-in", that is, they travel all the way to the back of their position, and instead of moving back-and-forth, they just move forward. Essentially, they cannot reproduce half the waveform. Incredibly high distortion.
There are magnet systems that prevent this, but usually the woofers with them are expensive. One reason I like to recommend the Peerless, when appropriate, is that it is inexpensive but it still has that magnet system.
Well, I checked the Blaupunkt's manual. It has a symmetric magnet system too. Very impressive for the price.
The Blaupunkt is a 4 ohm speaker, the Peerless an 8 ohm speaker. Makers of 4 ohm speakers often have a sneaky way of stating their sensivity so that the speaker is listed as 3 dB higher than it really plays. Long story, I'll explain later if you want. Well, the Blaupunkt does not do that, It is a genuine 90 dB@1W/1M. Actually, 89.5 dB, but rounded off it is 90 dB. So the Blaupunkt is about 1.5 dB more sensitive than the Peerless.
Your Parts Express subwoofer amp gives off 250 watts into 4 ohms, and only 150 watts into 8 ohms. That is about 3 dB higher for the 4 ohm speaker-the Blaupunkt. Add to that the 1.5 dB higher efficiency, and the Blaupunkt can be driven to 4.5 dB higher level than the Peerless.
The Parts Express amp has instructions on how to boost the output at 30 Hz, so the Blaupunkt can put out equally to the Peerless at 30 Hz. Above 40 Hz, the Blaupunkt can be driven to 4.5 dB higher than the Peerless. Put another way, throughout most of the bass range, the Peerless would require a 450 watt amp to play as loud as the Balupunkt does on your Parts Express 250 watt amp.
I will contact the tech department of Blaupunkt on Monday to double check the way they measure Xmax, but I am sure it is the center-front, not back-to-front. Assuming it is center-to-front measurement, I would say that, with the Blaupunkt, you selected an excellent woofer for the price. It is one that I will recommend to other people.
Before I can absolutely say that the Blaupunkt is the best speaker for the job, I have to check one thing with their technical department. The Xmax-the back and forth movement of the cone-is listed as .25 inch. For many speaker manufacturers, that means .25" from midpoint to front, then .25" from midpoint to back. However, some speaker manufacturers measure all the way from the back of the speaker's travel to the front. That is quite a difference. I am pretty sure that Blaupunkt measures from center to front, but I want to check. I will do so Monday.
One of the reasons I liked the Peerless woofer so much was that it had a symmetric magnet system. There is more magnet behind the voice coil than in front, in most speakers. As a result, near the tuning frequency in a vented box, most speakers experience "suck-in", that is, they travel all the way to the back of their position, and instead of moving back-and-forth, they just move forward. Essentially, they cannot reproduce half the waveform. Incredibly high distortion.
There are magnet systems that prevent this, but usually the woofers with them are expensive. One reason I like to recommend the Peerless, when appropriate, is that it is inexpensive but it still has that magnet system.
Well, I checked the Blaupunkt's manual. It has a symmetric magnet system too. Very impressive for the price.
The Blaupunkt is a 4 ohm speaker, the Peerless an 8 ohm speaker. Makers of 4 ohm speakers often have a sneaky way of stating their sensivity so that the speaker is listed as 3 dB higher than it really plays. Long story, I'll explain later if you want. Well, the Blaupunkt does not do that, It is a genuine 90 dB@1W/1M. Actually, 89.5 dB, but rounded off it is 90 dB. So the Blaupunkt is about 1.5 dB more sensitive than the Peerless.
Your Parts Express subwoofer amp gives off 250 watts into 4 ohms, and only 150 watts into 8 ohms. That is about 3 dB higher for the 4 ohm speaker-the Blaupunkt. Add to that the 1.5 dB higher efficiency, and the Blaupunkt can be driven to 4.5 dB higher level than the Peerless.
The Parts Express amp has instructions on how to boost the output at 30 Hz, so the Blaupunkt can put out equally to the Peerless at 30 Hz. Above 40 Hz, the Blaupunkt can be driven to 4.5 dB higher than the Peerless. Put another way, throughout most of the bass range, the Peerless would require a 450 watt amp to play as loud as the Balupunkt does on your Parts Express 250 watt amp.
I will contact the tech department of Blaupunkt on Monday to double check the way they measure Xmax, but I am sure it is the center-front, not back-to-front. Assuming it is center-to-front measurement, I would say that, with the Blaupunkt, you selected an excellent woofer for the price. It is one that I will recommend to other people.
As for the ports, there is an adjustment to be made if the opening of the port lies along one of the interior walls of the enclosure. You do want to leave a few inches between the port opening and any walls, as well.
The port can lay along the inside wall of the enclosure as long as the opening is a few inches away from any obstruction. The air must be able to enter and leave the port without any blockage or slowdown..
You probably want to line the interior of the walls of the enclosure with stuffing. Just line the walls-don't fill the enclosure as some people do with a closed box. The air must flow freely in a ported box for it to work properly.
Feel free to ask me any question you wish. If I don't hear from you, I will post Monday and let you know about the excursion question I have for Blaupunkt technical department.
The port can lay along the inside wall of the enclosure as long as the opening is a few inches away from any obstruction. The air must be able to enter and leave the port without any blockage or slowdown..
You probably want to line the interior of the walls of the enclosure with stuffing. Just line the walls-don't fill the enclosure as some people do with a closed box. The air must flow freely in a ported box for it to work properly.
Feel free to ask me any question you wish. If I don't hear from you, I will post Monday and let you know about the excursion question I have for Blaupunkt technical department.
thanks a ton!
i will take your advice about the port and i am looking forward to hearing from you one monday about the tech stuff.....
as for tomorrow i am building the enclosure tomorrow.....
i took your advice and got some 1/4 in craft foam...dont ask...
my friend has had tremendous succuss with this foam and it looks good too...
i am so greatful to have met some one like you here and i hope to stay in contact....
as for a nother q.....
do you think i should get and elbo to tilt the port downward so it is less likely to be too close to the back wall......
kind of like this....
(sorry for the bad art)
i will take your advice about the port and i am looking forward to hearing from you one monday about the tech stuff.....
as for tomorrow i am building the enclosure tomorrow.....
i took your advice and got some 1/4 in craft foam...dont ask...
my friend has had tremendous succuss with this foam and it looks good too...
i am so greatful to have met some one like you here and i hope to stay in contact....
as for a nother q.....
do you think i should get and elbo to tilt the port downward so it is less likely to be too close to the back wall......
kind of like this....
(sorry for the bad art)
Attachments
::::::::::::::::::::::::::::::::::::::Slicemaster:
Thanks for the kind words.
I think your port and elbow is about right.
One small thing. You can put the port just about anywhere, but most people prefer closer to the bottom of the enclosure, so the closeness to the floor might increase bass response just a bit. Of course, then the elbow will be pointing up into the enclosure if you do it that way. You can also put the port in back if you want.
I am not sure I have heard of craft foam, but if it worked, it worked.
One tip. You want to make sure the box is airtight, even though it is ported. Use construction adhesive to line the inside of all the joints after the box is together.
Good idea to post the pictures of the enclosure. Yes, I would like to see those pictures. You give me too much credit though. You are the one who is making this come about, not me!
Thanks for the kind words.
I think your port and elbow is about right.
One small thing. You can put the port just about anywhere, but most people prefer closer to the bottom of the enclosure, so the closeness to the floor might increase bass response just a bit. Of course, then the elbow will be pointing up into the enclosure if you do it that way. You can also put the port in back if you want.
I am not sure I have heard of craft foam, but if it worked, it worked.
One tip. You want to make sure the box is airtight, even though it is ported. Use construction adhesive to line the inside of all the joints after the box is together.
Good idea to post the pictures of the enclosure. Yes, I would like to see those pictures. You give me too much credit though. You are the one who is making this come about, not me!
i think i will keep the port where it is just because i dont want to have to redesign again...thanks for the tip anyway....
and do you know of any good webpages that give indepth instructions on how to paint and finish the enclosure......
i found a breaf one but i would like more details.....
if you know how your comments are always welcome....
thanks.......
and do you relly think placing the port at the bottom it worth the hassle? thanks.....
what product do you reccomend for sealing the inside of the enclosure.....
i alreddy have some relly cilicon culk for the joints but what do you think i should use for the rest of the inside?
water sealer?
or what....
thanks
and do you know of any good webpages that give indepth instructions on how to paint and finish the enclosure......
i found a breaf one but i would like more details.....
if you know how your comments are always welcome....
thanks.......
and do you relly think placing the port at the bottom it worth the hassle? thanks.....
what product do you reccomend for sealing the inside of the enclosure.....
i alreddy have some relly cilicon culk for the joints but what do you think i should use for the rest of the inside?
water sealer?
or what....
thanks
As long as the port is within 2 feet of the floor, or less, that is really all that is necessary. If a redesign is a hassle, I wouldn't do it.
Silicon is great for sealing the inside joints. Make sure it is the clear silicon, not the white stuff for sealing bathroom enclosures. The white stuff is silicon rubber mixed with caulk, and does not last as long. Get the pure silicon rubber.
I don't think you need to coat the inside of the enclosure with anything. Building material should be at least 3/4" thick.
Looking forward to seeing those pictures.
Silicon is great for sealing the inside joints. Make sure it is the clear silicon, not the white stuff for sealing bathroom enclosures. The white stuff is silicon rubber mixed with caulk, and does not last as long. Get the pure silicon rubber.
I don't think you need to coat the inside of the enclosure with anything. Building material should be at least 3/4" thick.
Looking forward to seeing those pictures.
---well i am done for the day and it is almost finnished!---
i looks so good!
all i need to do now is sand it and put the woofer and amp in!
well i am still looking for a resorce on how to paint the sucker so it looks good.....
so please post that......
thankyou kelticwizard for all the help.....
i am looking forward to hearing more from you....
well every thing worked out perfictly.....
i even got some steel brackets to brace the inside walls......
well please any one who knows or wants to help me out finding a good site that tell me how to paint this thing....please post links!
i will post pictures of final product in a cuple of weeks when every thing is in....
i will check the board for new messages every day.......
--==note==-- all the screws are counter sunk and the holes will be filled with puddy and sanded....this has not been done yet in pictures
Slicemaster:
Beautiful job!! Everything looks great!
The boxes you have are perfectly good to load in your Blaupunkt and start going. However, I think I might bring up the subject of bracing.
Two cubic feet has been sort of standard size for speaker boxes since at least the 1960's, as a compromise between volume for the bass and livable dimensions. Some perfectly good boxes did not use internal bracing, some did.
So it is purely optional on your part, since you can live without it.
If you do decide to add some though, I would go about it this way.
The metal speaker frame will brace the front. The back requires a 9" X 9 1/4" cutout for the subwoofer amplifier, which should also serve to brace the back. That leaves the top, bottom, and sides.
Using anything from a 1" X 3" hardwood piece or a 2 by 4, cut two pieces that fit across the top and bottom going from one side to the other, (not front-to-back). Looks to be about 15" across, by the looks of it. Then cut the pieces to go up and down the sides, which will meet the other pieces you cut which run along the top and bottom. Then attach the bracing to the inside of the cabinet.
Since you have sealed the joints and even used metal braces, you can cut the corner of the wooden brace to fit over them. All of this should be able to be done through the hole for the speaker cutout.
There are a couple of ways to glue the bracing to the inside of the cabinet, including one that does not require screws fron the outside of the box. You might not want to put screws in from the outside.
Again, this is all optional. You can use the box "as is" and it will be fine, since it clearly is a very well-made enclosure.
PS: I just checked Parts Express. Are you going to be using the subwoofer amp with or without the remote control? The remote control model seems to be only $6 more.
Beautiful job!! Everything looks great!
The boxes you have are perfectly good to load in your Blaupunkt and start going. However, I think I might bring up the subject of bracing.
Two cubic feet has been sort of standard size for speaker boxes since at least the 1960's, as a compromise between volume for the bass and livable dimensions. Some perfectly good boxes did not use internal bracing, some did.
So it is purely optional on your part, since you can live without it.
If you do decide to add some though, I would go about it this way.
The metal speaker frame will brace the front. The back requires a 9" X 9 1/4" cutout for the subwoofer amplifier, which should also serve to brace the back. That leaves the top, bottom, and sides.
Using anything from a 1" X 3" hardwood piece or a 2 by 4, cut two pieces that fit across the top and bottom going from one side to the other, (not front-to-back). Looks to be about 15" across, by the looks of it. Then cut the pieces to go up and down the sides, which will meet the other pieces you cut which run along the top and bottom. Then attach the bracing to the inside of the cabinet.
Since you have sealed the joints and even used metal braces, you can cut the corner of the wooden brace to fit over them. All of this should be able to be done through the hole for the speaker cutout.
There are a couple of ways to glue the bracing to the inside of the cabinet, including one that does not require screws fron the outside of the box. You might not want to put screws in from the outside.
Again, this is all optional. You can use the box "as is" and it will be fine, since it clearly is a very well-made enclosure.
PS: I just checked Parts Express. Are you going to be using the subwoofer amp with or without the remote control? The remote control model seems to be only $6 more.
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