need some help with a speaker re-build project???

[stevenlevel 146]

Hi I'll try to keep this short but need to explain what I'm trying to do here:

 

I have an old non-powered sub that's been used as furniture for many years now and I decided to turn it into a dual 10" sealed powered sub.

 

I found two nice 10" drivers with 2" voice coils for only $35 at PartsExpress. So these are 4 Ohm woofers that I plan on wiring in series turning the 2 drivers into a 8 Ohm load and will be powered by a Audio Source Amp 100 in it's mono mode of 160 watts.

 

My main question is how to use a high pass in line RCA filter at 100 or 80 HZ so the woofers only play low bass.

 

So I'll have 2- 10" woofers playing the same mono output from my Carver C-1 preaout 2 right or left channel.

 

Then I'll run from the pre-out 2 to the Audio Source amp 100's RCA input and then run the speaker wire from the amp to the subs two drivers.

 

So can I place a inline 80 or 100 HZ high pass filter into the secondary amps input to get the proper bass frequencies I need? The amp has a volume control to adjust the output and is rated at 1% THD just like most powered subs are.

 

So will this setup work as I have stated it? If not please explain. Also any suggestions or feedback is always welcomed by you wonderful people.

 

Thanks in advance. Steven Level 

 

 

 

 

 

 

 

[RobertR 847]

You'll want a low pass filter, not a high pass!

 

Just for fun, you might try using your amp in it's stereo configuration, and run one driver with left and the other with right channel information.  Sometimes a bass instrument is recorded well to one side, and that can result  a balance problem with a single channel hookup.

 

RobertR

[fill35U 1,847]

Cool project, Steven!  Got pics?

 

+1 to what RobertR suggested. You definitely need a low-pass filter... You'll get 120W out of that amp with the two 4 ohm drivers in stereo, vs. the 150W bridged into both in series, but the difference in power will be inaudible. 

 

As another good reason for running in stereo, it's generally a bad idea to run (sub)woofers in series. Differences in driver parameters can make them share the load unequally. They also couple to each other acoustically, i.e. the sound from one can affect the other. Not a problem with *dual voice coil* drivers interacting with themselves, because the coils are mechanically linked together.

 

Have you done any calculations for optimizing the volume of the cabinet with the drivers you're using? What's the Parts Express part number for your woofers?

[kve777 6,896]

Woofers or Subwoofers? I entered your parameters for woofers and found none, for subwoofers and found only one at $39. None at $35. Yes, what is the part number?

 

BTW- I have a good working Klipsch KSW 10 Subwoofer amp for $40.00 + shipping. You can use it with a PE subwoofer in your cabinet and have all the features of a regular sub.

 

KSW 10 Type: 10" bass reflex, tuned port enclosure Amplifier: Peak output power 225 watts into 4 ohms FTC Rated Power: 55 watts continuous, 22-125Hz @ 1% THD m a x i m u m Auto Power On: 2 second ON delay, 15 minute OFF delay Frequency Response: 29-120Hz±3dB Maximum Acoustic Output: 110dB 1 /8 space 1 meter Low Pass Crossover: Continuously variable from 40-120Hz, 24dB/octave slope above 120Hz Inputs: 2) Line level RCA phono jacks 2) High level speaker terminals Phase: Switchable 0-180 degrees Drive Component: K-1070-K 10" (25.4cm) driver

 

 Manual

[stevenlevel 146]

I was going to use these in some Cerwin-Vega RE-24's that had blow woofers and just seal the speakers enclosure and get rid of the port as these drivers Part# 299-2188 are best when used in a sealed enclosure.

 

So I can still just cut out the port tube and seal these old C-V speakers from 1994 and use them with these 10" woofers.

 

Then I thought why not try getting my old and very large old non powered stereo sub working again if these drivers will perform good enough.

 

They weigh 7.25 lbs each and at $17.50 each and 55% of retail price of $40 each I figured I could try using them in my old non-powered sub that is non ported and was a stereo subwoofer.

 

No one ever stated if a lowpass inline RCA would work to filter out from 100 or 80 HZ if they were plugged into the amps inputs? 

 

These drivers look as though they they will work well enough but they are not high end sub-woofers per say.

 

They are rated down to 39 HZ which is good enough and I just thought I could at least try them in the old sub just to see how they sounded. Since the amp has a volume control and a balance control it should be pretty good for driving these two 4 Ohm drivers.

 

Can someone tell me which inline pair of lowpass filters I need from Parts Express? They are not cheap at about $30 for a pair but if they will work and these 10" drivers also get low enough I'll buy them.

 

Love the idea of a stereo sub like it was before. Didn't even think of that but the amp can handle 4 Ohm loads so why not?

 

I didn't order the inline filters yet since I didn't know if they would work. As mentioned I bought these 10" replace the blown 10" woofers in a rescued pair of C-V 3 way speakers and these were rated as the best to replace those drivers if I eliminated the rear port which would be simple.

 

But then I began to think about the extra amp and using it to drive both these drivers mounted in my old large sealed stereo non-powered sub that I have had forever.

 

Thanks again for all the feedback in advance and if you guys can give me the part # for the inline low pass filters that would be great. Thanks again and sorry if I was redundant here. Steve 

 

 

 

 

[stevenlevel 146]

I think my Hafler DH-500 or my C-1 preamp has some faulty resisters or caps as I'm getting some excessive hiss at full volume of the MM phono stage.

 

It odd as one channel is super clean and one channel produces more hiss than I ever heard before.

 

Was thinking I need re-ground the amp with a STAR ground like it had before I replaced the RCA inputs but it's hard to do. I was able to replace the RCAs but there is no room to work in the back of the amp unless I'm willing to remove a bunch of parts like the two main large caps.

 

Just not sure how to get the amp grounded correctly so it produces no audible hum of hiss like it did before I messed around with it. It's only audible at near full volume so most music playback is not effected but it bothers me just knowing it's there when it was not before I replaced the RCA inputs. 

[fill35U 1,847]

No worries, Steven! 

 

Yes, the inline low pass RCA devices (Harrison Labs FMOD) should work fine. The 100 Hz low pass ones at Parts-Express HERE .

The drivers you're using really want a large sealed box, like 3 or 4 cubic feet *each*. If you put them both in the same enclosure, that enclosure should be 6 to 8 cubic feet. If it's much smaller than that, you'll lose more low frequency, and you're already starting high for a modern subwoofer. Plus your amp won't have the power to force more out of the low end with EQ, even though the speakers might handle it.

 

Glad you're bringing that old speaker back to life!  

[stevenlevel 146]

Will 60 watts per channel be enough power? The amp100 I have shows 60 watts per channel into 4 Ohms and not 140.

 

It's odd as it's 50 watts per channel into 8 Ohms but only bumps up to 60 with a 4 Ohm load.

 

This amp was bought to power my rear Definitive Bi-Poles and runs off my Yamaha receiver rear speaker outputs right now.

 

The size of the sub is very large compared to the 12" powered sub that's sitting on top of it currently.

 

It's at least twice the cubic feet of the 12" Dayton Audio powered sub that's sitting on top of it.

 

This was purchased back in 1983 as a kit from Chicago Speakerworks. I bought the satt's or bookshelf speakers first in 1982  for $325 a pair and then worked a part time job at 15 to save up for the stereo non-powered sub that cost $350 in kit form.

 

My dad was an audiophile back in the day and thought they were by far the best speakers I could afford to buy.

 

The satts still work and actually still sound pretty good to this day. They had a 5" peerless coated driver with rubber surround and a 1"soft dome tweeter. The stereo sub actually was working until 2 years ago when the cross-overs caps blew apart making the inside of the sub look like the yard the day after a fire works display.

 

I thank you guys for the info. Can I run the woofers without the low pass filters to test it safely?

 

Would you get the 100 HZ or 80 HZ low pass filters? I was thinking 100 HZ as the drivers should get down to about 35 HZ as the sealed enclosure is built like a tank.

 

I also bought new gasket sealing tape and good deep threaded screws to get my main front speakers sealed air tight and get rid of any stripped screws as well.

 

My front Definitive 450's don't sound even to me in output as the left seems to be playing louder to me.

 

So I'm going to replace both 6 1/2" with new one's sent from Definitive for free and make sure they are mounted perfectly and air tight. Same for the 10" side mounted passive rads as a few of the screws may be stripped causing air leakage.

 

Hopefully, when I'm done doing all this the front speakers will sound exactly the same as air leakage is a big issue that needed to be addressed.

 

 

 

 

 

 

 

 

 

 

[stevenlevel 146]

 

 

Cool project, Steven!  Got pics?

 

+1 to what RobertR suggested. You definitely need a low-pass filter... You'll get 120W out of that amp with the two 4 ohm drivers in stereo, vs. the 150W bridged into both in series, but the difference in power will be inaudible. 

 

As another good reason for running in stereo, it's generally a bad idea to run (sub)woofers in series. Differences in driver parameters can make them share the load unequally. They also couple to each other acoustically, i.e. the sound from one can affect the other. Not a problem with *dual voice coil* drivers interacting with themselves, because the coils are mechanically linked together.

 

Have you done any calculations for optimizing the volume of the cabinet with the drivers you're using? What's the Parts Express part number for your woofers?

 

What if the sub is divided with a board in the middle that isolates each woofer?

 

Would that allow both drivers to play mono without any issues? 

 So one for each 10" woofer and non-ported which will allow these 7+ LB woofers to play at there lowest, as they are designed to play in sealed cabinets.

 

I realize these drivers I'm using are not high end subwoofers that cost over $100+ each. However, they do have 2" voice coils and can handle 150 RMS for what that's worth? 

 

I'm hoping you will respond back as the amps manual says only 60 watts into a 4 Ohm load which is odd since it's rated at 50 into 8. Is the manual possibly wrong with the 4 Ohm rating?.

 

I would love to go with a stereo powered sub if possible but do you really think that 40 to 50 watts for each driver will produce enough bass without me clipping the amp? 

 

I hooked this amp up to my main system just to test it well and it sounded horrible if I pushed the volume up beyond 50% with my phono stage on my C-1 preamp playing vinyl. Lots of hum was produced if I turned the amps volume knob up above 50% or so.

 

I hope you hit me back and can help with these ??s If these is a better amp that I can buy used for this sub on Ebay I'll look into it? This amp is currently driving my Definitive BP1x rear surrounds since my Yamaha receiver allows a secondary amp for the rear speakers, and it's fine it that role as I paid only $60 for it and they are very small Bi-Poles.

 

I'm sorry to bother you again but everyone sort of moved on with this post even though I had a few questions un-answered.

 

I know PE has sub only amps with the variable cross-overs that would work well but the one I wanted is nearly $300

 

Please everyone come back and help??? 

 

 

 

 

 

 

[4krow 7,210]

   I wish that I still had the Harrison module that I used way back, because it was able to act as a line level crossover for just such an application as yours. You could choose frequency and even slope. It was a little passive type black box that was easy to adjust and if nothing else, would give you and idea if you were going in the right direction or not. Might be a good idea to look at all the products that Harrison Labs have to offer. 

[4krow 7,210]

http://www.hlabs.com/products/crossovers/index_files/Page384.htm

 

 

 

 I somehow got this right 

[fill35U 1,847]

What if the sub is divided with a board in the middle that isolates each woofer?

 

I would advise this approach regardless of connections, because the divider will stiffen and strengthen the box. And if one driver (or amp channel) fails, the other driver won't suddenly see twice the effective box volume with a lousy passive radiator (potential over excursion). Since you're going sealed, I don't think it'll make as much difference as to divided or not if you wire in series, which I still think is to be avoided. 

 

Would that allow both drivers to play mono without any issues?

 

Any issues from series wiring will still be there. I still think better to drive each woofer with its own channel. But hey, it's very easy to try it both ways and see for yourself, if you bring connections out for each driver (two pair of speaker terminals on the side of the cabinet). 

 

So one for each 10" woofer and non-ported which will allow these 7+ LB woofers to play at there lowest, as they are designed to play in sealed cabinets.

 

With those woofers, a relatively big sealed box is as good as you'll get for lowest bass extension. Unless you're willing go go Infinite Baffle, which these woofers would also do well at.

 

Magnet weight isn't everything, just look at the woofers in Amazing Loudspeakers. Or neodymium magnets.  

 

I realize these drivers I'm using are not high end subwoofers that cost over $100+ each. However, they do have 2" voice coils and can handle 150 RMS for what that's worth?

 

I would put more trust in the specs for an expensive driver than for a very inexpensive one. Testing costs money, there's more room for profit after testing in extensive drivers, and folks who spend more money usually have a higher expectation of performance and agreement to specs. But assuming the power handling spec is trustworthy, it means the driver is capable of handling more power than your amp can put out, even at full clipping. This is not a bad thing for toughness, but if you put the woofers in a much smaller than optimum box, that amp might not be able to drive those woofers to full excursion for full output on the bottom end. Again, not bad for the safety of the drivers, though.

 

I'm hoping you will respond back as the amps manual says only 60 watts into a 4 Ohm load which is odd since it's rated at 50 into 8. Is the manual possibly wrong with the 4 Ohm rating?.

 

Power specs like those usually mean the amp has a marginal power supply or current capability. Shell probably be struggling with those woofers, either 4 ohms stereo or 8 ohms bridged. Not much you can do about that without changing woofers or amp, but try and see! It may sound terrific! 

 

I would love to go with a stereo powered sub if possible but do you really think that 40 to 50 watts for each driver will produce enough bass without me clipping the amp?

 

 

Depends on the music, the room, where you place the sub, your preferences, and how well the amp tolerates clipping,  

 

I hooked this amp up to my main system just to test it well and it sounded horrible if I pushed the volume up beyond 50% with my phono stage on my C-1 preamp playing vinyl. Lots of hum was produced if I turned the amps volume knob up above 50% or so.

 

Sounds like something's not right. Do you get the same hum if you use a different amp, but keep everything else the same? 

 

I hope you hit me back and can help with these ??s If these is a better amp that I can buy used for this sub on Ebay I'll look into it? This amp is currently driving my Definitive BP1x rear surrounds since my Yamaha receiver allows a secondary amp for the rear speakers, and it's fine it that role as I paid only $60 for it and they are very small Bi-Poles.

 

Considering that you can find used but working 5.1 receivers on eBay with 100W/channel for $60 or less, I'd say you've got almost limitless options. The nice thing about dedicated sub amps ("plate amps") is that the usually have features like auto-on, adjustable low-pass frequency, and phase adjustment. See the one kev777 was offering above...

 

I'm sorry to bother you again but everyone sort of moved on with this post even though I had a few questions un-answered.

 

No worries, it's been a busy holiday weekend! 

 

I know PE has sub only amps with the variable cross-overs that would work well but the one I wanted is nearly $300

 

The majority of them are less than that, and there are a few where a pair would cost you less than $200: SUBWOOFER PLATE AMPS AT PARTS-EXPRESS.COM 

[stevenlevel 146]

 

 

http://www.hlabs.com/products/crossovers/index_files/Page384.htm

 

 

 

 I somehow got this right 

 

 

This looks like it would be better than using the standard RCA type inline adapters.

 

Is this for a stereo signal that gets mixed into a mono signal? That's what it looks like but I can't tell exactly what this actually does other than that. I also don't quite understand how this works?

 

Can you please explain how this works? Is this a simple device that is placed between the amps inputs and the amp being used?

 

 

[4krow 7,210]

   The web page that I directed you to explains all of the questions that you have.

[fill35U 1,847]

 

 

 

http://www.hlabs.com/products/crossovers/index_files/Page384.htm

 

 

 

 I somehow got this right 

 

 

This looks like it would be better than using the standard RCA type inline adapters.

 

The main advantage is that it's parametric, i.e. you can change the crossover point(s) with jumpers instead of having to buy different FMOD attenuators. Some models of that PFMOD also have parametric high-pass filters for your main amp and speakers.

 

 

Is this for a stereo signal that gets mixed into a mono signal? That's what it looks like...

 

It takes a stereo signal from your preamp. From there it depends on the model, but it looks to me like all the low outputs are summed mono. So even if they have two output jacks for the lows, they're both sending the same signal. 

 

 

but I can't tell exactly what this actually does other than that. I also don't quite understand how this works?

 

Can you please explain how this works? Is this a simple device that is placed between the amps inputs and the amp being used?

 

Yes, thats where this would go, same as the FMOD attenuators mentioned previously, or any other line level crossover. These PFMODs are adjustable, and some models can also cross over the high frequencies to another amp. Which is often desirable, as it lets your main amp and speakers work less hard if they're not trying to reproduce the lows that your sub is taking care of.