Subwoofer amp?

[Speculant]

I recently discovered a 7" speaker in my closet, and I want to make a woofer out of it. Would this work just fine? Is it the cheapest option for a good quality sub amp?

 

[GranteedEV]

Why not just run the sub passive off of your receiver?

More importantly, do you even have the T/S paramters of the driver? It may just be a 7" midrange.

 

[Speculant]

I don't have a spec sheet for the driver, but tomorrow I will post what is printed on the back, and I will try to find the serial number of it.

Also, what do you mean by "run the sub passive off of your receiver"?

 

[TLS Guy]

I recently discovered a 7" speaker in my closet, and I want to make a woofer out of it. Would this work just fine? Is it the cheapest option for a good quality sub amp?

You really need to do some reading before anymore posts. Honestly your posts are quite idiotic.

You don't even know if this is a sub driver and I doubt it is. You just have no clue at all about speakers and how they work.

25 watts is not enough power for any decent sub.

To design a sub, you need a sub driver and you must know or measure the Thiel/Small parameters before you can begin.

 

[GranteedEV]

25 watts is not enough power for any decent sub.

Well you could probably make a tapped horn...

 

[Speculant]

You really need to do some reading before anymore posts. Honestly your posts are quite idiotic.

You don't even know if this is a sub driver and I doubt it is. You just have no clue at all about speakers and how they work.

25 watts is not enough power for any decent sub.

To design a sub, you need a sub driver and you must know or measure the Thiel/Small parameters before you can begin.

Ouch, dude. I guess I'll do some reading before posting more.

 

[TLS Guy]

Well you could probably make a tapped horn...

A huge exponential horn is about the only way you could do it.,However after going to that massive amount of work you would want something a lot better.

 

[highfigh]

You really need to do some reading before anymore posts. Honestly your posts are quite idiotic.

You don't even know if this is a sub driver and I doubt it is. You just have no clue at all about speakers and how they work.

25 watts is not enough power for any decent sub.

To design a sub, you need a sub driver and you must know or measure the Thiel/Small parameters before you can begin.

C'mon, don't sugar-coat it, tell him how you really feel.

 

[Swerd]

Speculant

For any woofer, to design a cabinet that performs correctly, you need to know at least three numbers: Fs, Qts, and Vas. They are often referred to as the Thiel/Small (T/S) parameters. Look in this example for those numbers.

Every manufacturer provides those values that they have measured. If you have the right tools and software, you can measure them yourself. Without those values, you can't make an intelligent choice, and you are essentially pissing in the dark on a windy day.

I won't try to explain how you go about designing a cabinet once you know the T/S parameters because it is fully explained in the book I mentioned to you earlier, Speaker Building 201. If you make the effort to read and understand that, we'll be happy to answer questions you have.

To answer your original question, I don't know of any 7" driver that was intended to be used as a subwoofer. Most 7" drivers I know of were meant to be used as mid-woofers in a 2-way speaker. Some really good examples might go as low as 35-40 Hz in an appropriate sized cabinet. And 25 watts RMS at 8 ohms is not nearly enough to work for a real subwoofer.

It would help me understand where you are coming from if I knew how old you are. Sometimes your questions remind me of my son when he was about 14 years old. He wanted to know everything - right now - without working to get the answers. If you are that young, inexperienced, but enthusiastic, go get that book and read the first few chapters. If you can't buy it, find it in a library. If you are older, but equally inexperienced, I have the same advice. Get that book and start getting smarter.

Don't take TLS Guy personally. He knows what he is talking about, and I would take any advice from him seriously, but his bark is worse than his bite .

 

[Speculant]

Speculant

For any woofer, to design a cabinet that performs correctly, you need to know at least three numbers: Fs, Qts, and Vas. They are often referred to as the Thiel/Small (T/S) parameters. Look in this example for those numbers.

Every manufacturer provides those values that they have measured. If you have the right tools and software, you can measure them yourself. Without those values, you can't make an intelligent choice, and you are essentially pissing in the dark on a windy day.

I won't try to explain how you go about designing a cabinet once you know the T/S parameters because it is fully explained in the book I mentioned to you earlier, Speaker Building 201. If you make the effort to read and understand that, we'll be happy to answer questions you have.

To answer your original question, I don't know of any 7" driver that was intended to be used as a subwoofer. Most 7" drivers I know of were meant to be used as mid-woofers in a 2-way speaker. Some really good examples might go as low as 35-40 Hz in an appropriate sized cabinet. And 25 watts RMS at 8 ohms is not nearly enough to work for a real subwoofer.

It would help me understand where you are coming from if I knew how old you are. Sometimes your questions remind me of my son when he was about 14 years old. He wanted to know everything - right now - without working to get the answers. If you are that young, inexperienced, but enthusiastic, go get that book and read the first few chapters. If you can't buy it, find it in a library. If you are older, but equally inexperienced, I have the same advice. Get that book and start getting smarter.

Don't take TLS Guy personally. He knows what he is talking about, and I would take any advice from him seriously, but his bark is worse than his bite .

Alright, thanks for the tips, I will definitely find that book and read it.

As for my age, I am a senior in high school. That should give you a good enough estimate on my knowledge level.

 

[gregz]

Alright, thanks for the tips, I will definitely find that book and read it.

As for my age, I am a senior in high school. That should give you a good enough estimate on my knowledge level.

Speculant, the first subs I bought as a teenager were from one of those huge liquidation sales in a stadium. I thought I'd gotten a sweet deal on a pair of 8's for only $20. I proceeded to build a shallow box out of 1/8 inch masonite, just big enough to fit each of them, fitted to the back shelf of my car. I ran them off a Radio Shack "40 Watt graphic equalizer," and got lots of sound but no real bass. They were horrible until the day their polypropylene cones cracked from sun exposure 6 months later.

For my next project, I bought a book on subwoofer design, and built two huge ported boxes for a pair of relatively inexpensive but decent 8" subs that were able to go quite low in a large enclosure. The boxes were so big the little 8's looked like zits. They took up my whole back seat. But they performed pretty darn well, even off that cheesey booster eq. From that point on, I had the bug, and I still have it 20 years and many speaker projects later.

My point is everyone starts somewhere, and there are worse crimes than not knowing anything and asking questions. If your 7" speakers aren't identifiable by the writing on the backs of them, there are ways to determine the thiele/small parameters but they're not easy and require some equipment most people don't own.

So let's start with the writing on the back, and go from there.

 

[Speculant]

It's an older Atlas/Soundolier (now just Atlas Sound) model.

It says "WD417-2V" on an upper portion on the back and "795410" on a lower portion on the back.

Googled some and found this spec sheet (this is pretty much the same thing as the pdf). I know that Hz/KHz isn't everything, but it can go down to 50Hz, which is from what I understand, pretty low.

It seems to me the bad thing is the power handling is only 15 watts. This seems a little weak. Overall, though, it looks to be a similar speaker (speaking in terms of quality) to this.

Now I just have to find out what the T/S parameters are.

 

[Swerd]

Alright, thanks for the tips, I will definitely find that book and read it.

As for my age, I am a senior in high school. That should give you a good enough estimate on my knowledge level.

That book was written by a high school teacher who actually taught speaker building as a course. It makes use of high school level math without any calculus. I hope you find it interesting.

... For my next project, I bought a book on subwoofer design, and built two huge ported boxes for a pair of relatively inexpensive but decent 8" subs that were able to go quite low in a large enclosure. The boxes were so big the little 8's looked like zits.

Those remind me of the cabinets I helped my son build for a high school science project. He used two of the same 8" woofers, one in a ported cabinet and one in a sealed cabinet. The ported cabinet was reasonably sized, but the sealed cabinet was as big as a two story doghouse. We could barely get it out of the basement.

 

[Swerd]

It's an older Atlas/Soundolier (now just Atlas Sound) model.

It says "WD417-2V" on an upper portion on the back and "795410" on a lower portion on the back.

Googled some and found this spec sheet (this is pretty much the same thing as the pdf). I know that Hz/KHz isn't everything, but it can go down to 50Hz, which is from what I understand, pretty low.

It seems to me the bad thing is the power handling is only 15 watts. This seems a little weak. Overall, though, it looks to be a similar speaker (speaking in terms of quality) to this.

Now I just have to find out what the T/S parameters are.

Well that tells us something. Atlas Sound makes public address systems like what you may have in your school. They seem to be made primarily for voice reproduction, not music. The spec sheets you found do tell us that these speakers are very sensitive, 96 or 97 dB at 1 watt at 1 meter is a lot louder than the 85 dB of the GRS woofer that Parts Express has. So even if they can handle only 15 watts, they will be very loud.

How good they sound is still a guess until we know more. You found the spec sheet at MCM Electronics. You could always ask them if they have anymore info about them.

I think it is a long shot that these will make a decent subwoofer, but it is still worth trying to find what you can about them.

 

[jinjuku]

You really need to do some reading before anymore posts. Honestly your posts are quite idiotic.

Way to welcome a newcomer I'll have to apologize on behalf of TLS Guy. It's not representative of how we do things around here.

To design an enclosure for any speaker their T/S parameters need to be known.

 

[Speculant]

I sent a email request for the T/S parameters, hopefully they will respond.

 

[TLS Guy]

Alright, thanks for the tips, I will definitely find that book and read it.

As for my age, I am a senior in high school. That should give you a good enough estimate on my knowledge level.

It would have been helpful to have known that from the beginning. I envisioned you as a red neck auto sound guy who was just starting to wander into HT!

I would encourage to pursue this hobby as you have an interest.

However forums like this can not teach you the foundation knowledge you require. We can guide and assist.

I was lucky to have good mentors during my school years. However I leaned that I had to do my home work and carefully research and consider my questions. If not is was not only a waste of time, but I found I did not get or really deserve the time of day of the highly knowledgeable individuals whose advice I sought.

Properly approached these individuals were extremely generous.

As far as that Atlas driver, there is no prospect of making a sub from any of their drivers. Even without the Thiel/Small parameters you can make an educated guess that the driver is not suitable because of their high sensitivity. Unfortunately there is a strong inverse correlation between sensitivity and bass extension.

 

[Speculant]

Ok, thank you for the valuable input. I tested the bass on this speaker just yesterday, and it wasn't as great as my cheaper woofer, so I figured that it wouldn't make a great woofer.

 

[webmailjojo]

powering a high powered subwoofer using a low powered amp

I have an question regarding using a "low-powered" amp (which was lying unused in my room) for powering my Bose 200W sub MB4. My bose sub is 8Ω and 200W with 110dB-SPL. The specifications of the amp plate is given below. I obtained this amp plate from an active speaker model FP-206 by brand POPE Professional

Amp specifications
Frequency Response 80Hz-20kHz
Sensitivity (1W/1M) -15dBu (line)
Power Rating 100 Watts Continuous. Pink Noise
200 Watts Program 400 Watts Peak
SPL 109dB
Crossover Frequency 1.9 kHz
Impedance 8 Ω


Do you think i can run them safety? I wouldn't be driving the volume too high.

 

[TLS Guy]

I have an question regarding using a "low-powered" amp (which was lying unused in my room) for powering my Bose 200W sub MB4. My bose sub is 8Ω and 200W with 110dB-SPL. The specifications of the amp plate is given below. I obtained this amp plate from an active speaker model FP-206 by brand POPE Professional

Amp specifications
Frequency Response 80Hz-20kHz
Sensitivity (1W/1M) -15dBu (line)
Power Rating 100 Watts Continuous. Pink Noise
200 Watts Program 400 Watts Peak
SPL 109dB
Crossover Frequency 1.9 kHz
Impedance 8 Ω

Do you think i can run them safety? I wouldn't be driving the volume too high.

Since the frequency response of that amp only extends to 80 Hz, it is useless for powering any sub.