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Need some guidance with Speaker building !

Gary Mattis

Gary Mattis

Active Member
Hi Everyone ! , I'm a speaker builder newbie ! , I have a speaker project that has been on the back burner for awhile now that I would like to get done . I have two doner SP 200 Sansui cabinets to use and they have everything except for 1 of the woofer's that I robbed for a Jukebox , they sounded terrible to me but the woofer actually sounded good in the jukebox, the other donar speakers are a pair of Alnico 12 inch Magnavox console speakers with Jensen horns and are 3 ways that look pretty terrible but sound pretty good - they sound much better then the Sansui SP200's , my Amplifier is a 30 watt 6V6 PP 1959 Bell Pacemaker 2221 model with a few mods , I used a good military sealed power supply and I changed the rectifier tube from a 6CA4 to a 6X4 instead , then I drilled air holes so that the amp could breathe better , It seemed to me that the 3 Amp heater rectifier was not really necessarily and it was burning up the power supply. I have not purchased my turntable yet but was thinking of a belt drive magnetic cartridge, I have a mini disc and a regular Sony CD player both with adjustable bit rates , my tape player is a MCS dual cassette player , Bogen tube FM tuner , so my speakers need to work good with all of that stuff ! . Both sets of speakers have crossover networks in them and my thought was to use the two Sansui 5 inch speakers with the Jensen horns and Magnavox 12's , cut the tweeter holes into a rectangle and mount the Jensen horns there and use the Magnavox crossover networks with a mid range mod . I guess I would need to do some calculations on the ohms of the mids and adjust the crossover networks for the mid speaker changes ? Am I on the right track with this speaker project ? , This is my first real speaker project ! , Maybe someone could guide me with the midrange changes , the Magnavox speakers sound very good like they are now I just thought I could improve them with bigger mids and better cabinets. I'm not a rich guy so I need to try to make do with what I have. Thanks for any help on this one !
 

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I'm just getting into speakers and am working on projects like your project.and sounds like you need a measurement setup.
http://www.parts-express.com/dayton-audio-umm-6-usb-measurement-microphone--390-808
http://www.parts-express.com/dayton...er-based-audio-component-test-system--390-806
and maybe a small amp:
http://www.parts-express.com/lepai-...dio-mini-amplifier-with-power-supply--310-300

Cheaper mics can be gotten off the bay and other places.

I already had the dbx measurement mic and a lexicon lamda usb sound card and built my own impedance jig.
Bacically this just modified for my setup.
https://sites.google.com/site/amateuraudio/projects-1/arta-limp-and-or-room-eq-wizard-impedance-jig.
Use a small realistic amp for my set up. Which has its own filter cal file to remove the built in loudness curve.
Then Holm Impulse, Arta, Room EQ Wizard to take measurements. Crossover designer and Box simulator. What
 
You should, at a minimum, find the cut off frequencies of both the woofer and the small horn. A real backyard approach to this is to use tones and find the frequency where the driver no longer makes any sound. That Sansui squawker may be something you can do without since older Maggie woofers approached being a single-driver speaker. I have a console with 12"Magnavox field coil drivers and there is no horn or tweeter. If you can go two-way instead of three-way, it greatly eliminates complexities. You may just need a filtering capacitor and/or a potentiometer in that situation. You really can't use a purpose-built crossover network and substitute drivers. The result will probably be bad.
 
Gary, I know what it's like working on an extremely limited budget. That's me. But do yourself a big favor and ditch the speakers you have now. Instead, get thee on a regular basis to every Goodwill, Savers, and ReStore at your closest larger city and begin the hunt for good speakers. You will be amazed at some of the things that show up for less than $10 - far less than you will invest in getting your current speakers to a listenable point. If you just want to tinker, fine. But if you want something on which to enjoy great music, hit the second hand stores with reckless abandon. You'll be glad you did.

GeeDeeEmm
 
Gary Mattis said:
Hi Everyone ! , I'm a speaker builder newbie ! , I have a speaker project that has been on the back burner for awhile now that I would like to get done . I have two doner SP 200 Sansui cabinets to use and they have everything except for 1 of the woofer's that I robbed for a Jukebox , they sounded terrible to me but the woofer actually sounded good in the jukebox, the other donar speakers are a pair of Alnico 12 inch Magnavox console speakers with Jensen horns and are 3 ways that look pretty terrible but sound pretty good - they sound much better then the Sansui SP200's , my Amplifier is a 30 watt 6V6 PP 1959 Bell Pacemaker 2221 model with a few mods , I used a good military sealed power supply and I changed the rectifier tube from a 6CA4 to a 6X4 instead , then I drilled air holes so that the amp could breathe better , It seemed to me that the 3 Amp heater rectifier was not really necessarily and it was burning up the power supply. I have not purchased my turntable yet but was thinking of a belt drive magnetic cartridge, I have a mini disc and a regular Sony CD player both with adjustable bit rates , my tape player is a MCS dual cassette player , Bogen tube FM tuner , so my speakers need to work good with all of that stuff ! . Both sets of speakers have crossover networks in them and my thought was to use the two Sansui 5 inch speakers with the Jensen horns and Magnavox 12's , cut the tweeter holes into a rectangle and mount the Jensen horns there and use the Magnavox crossover networks with a mid range mod . I guess I would need to do some calculations on the ohms of the mids and adjust the crossover networks for the mid speaker changes ? Am I on the right track with this speaker project ? , This is my first real speaker project ! , Maybe someone could guide me with the midrange changes , the Magnavox speakers sound very good like they are now I just thought I could improve them with bigger mids and better cabinets. I'm not a rich guy so I need to try to make do with what I have. Thanks for any help on this one !
Click to expand...

First things first, I will assume you want to use the cabs you have. Let's start with a list of what you need to do:

1. Measure the inside of the cabinet inside and calculate its volume, preferably in Cubic Ft. and also the metric conversion to Liters.
2. What is the actual diameter of the holes where the drivers will go.
3. Check on the internet for the cut off frequencies of the crossover. Usually in the manufacturer's literature for speaker models you will find at which Hz are the cut-off. If it reads 250/2000 or 2K it means that it is a 3-Way speaker where the woofer to mid cut is at 250Hz and the mid to tweeter cut is at 2,000Hz (2K).

This is your first project, a good learning experience, let's not get very technical. The problem here and in many places, I fault at that many times, is that as a beginner one is anxious and excited about the project, and those with experience tend to get very technical and some think that one already knows many of the things they know. This is like loosing your virginity, you are anxious and excited, you don't know sh*t about what you are doing, but in your head you are thee best; the reality is that you're NOT! But, you enjoy it very much, and as you do it more times and read or watch movies about the subject you get better at it, and once you understand the female body and mind then you become great at it. It takes time, practice, simulations and patience.

When you have the info, advise.
 
PR Audio said:
This is your first project, a good learning experience, let's not get very technical. The problem here and in many places, I fault at that many times, is that as a beginner one is anxious and excited about the project, and those with experience tend to get very technical and some think that one already knows many of the things they know.
Click to expand...

I could not agree with you more. And my intention is not to pour water on Gary's enthusiasm. I have over fifty years of failed speaker-building projects behind me, and I enjoyed the heck out of every one of them! It wasn't until the advent of the internet that I began to actually understand enough of the process to begin building speakers the way they should be built - and I'm still learning.

I'm happy that you've jumped in with helping him on his project. Maybe between the two of you he can put together something listenable. The fun is in the process. Good luck, Gary. And keep us informed on your progress.

GeeDeeEmm
 
gdmoore28 said:
Gary, I know what it's like working on an extremely limited budget. That's me. But do yourself a big favor and ditch the speakers you have now. Instead, get thee on a regular basis to every Goodwill, Savers, and ReStore at your closest larger city and begin the hunt for good speakers. You will be amazed at some of the things that show up for less than $10 - far less than you will invest in getting your current speakers to a listenable point. If you just want to tinker, fine. But if you want something on which to enjoy great music, hit the second hand stores with reckless abandon. You'll be glad you did.

GeeDeeEmm
Click to expand...

GD's advice is sage, and I don't think it's pouring scalding urine on anyone's parade. Finding a complete set of factory made speakers at a thrift store and restoring them is a far better training ground than a mish-mash of disparate parts of questionable quality and unknown specs. Find a set of Boston Acoustics for a song, spend a little money on some foam surrounds (MAT Electronics), capacitors (Parts Express) and wood patch (Home Depot).
Once those Bostons are sounding good, you'll have a reasonable, more pragmatic foundation to further build upon.
 
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Two questions ? First ; Can I sub a 9.9 ohm mid for a 7 ohm midrange speaker ? , If so can I use 2 of them wired in parallel ? I'm trying to increase the midrange some , the highs and lows sound great. Both networks used similar coils and caps. 3.9 ohm on the dual midrange and 4 ohm on the single midrange.
 
Rebuilding or enhancing what you have is certainly doable!

However lets get to some "middle ground" with the level of performance you are looking to achieve. As some posters have noted you may be disappointed with the ability of the Sansui speakers to compliment your set up. Sansui was not known to create "memorable" drivers nor cabinets. This said, they can be enhanced at the sake of durability.

So.... go ahead and give it a go, there are plenty of support suppliers.. IE: Parts Express, Madisound, and several others.

Remember to give an after-action, same or new post, and we'll give you additional pointers as you "climb the HIFI scale" :banana:
 
gdmoore28 said:
I could not agree with you more. And my intention is not to pour water on Gary's enthusiasm. I have over fifty years of failed speaker-building projects behind me, and I enjoyed the heck out of every one of them! It wasn't until the advent of the internet that I began to actually understand enough of the process to begin building speakers the way they should be built - and I'm still learning.

I'm happy that you've jumped in with helping him on his project. Maybe between the two of you he can put together something listenable. The fun is in the process. Good luck, Gary. And keep us informed on your progress.

GeeDeeEmm
Click to expand...

GD, I'm glad you agree... Tell me about failed projects, the good outcome is the spare parts one owns after those projects, very useful for the next one.

BTW, people here have good intentions, and their advice, experiences, and knowledge are not to be taken lightly; it is just that at times it can be too much info and confusing to put it all in order. OP will get it, just takes lot of reading and practice, it is a mix of tech and art. Like GD said, the internet is a great DIY resource.

Gary Mattis said:
Two questions ? First ; Can I sub a 9.9 ohm mid for a 7 ohm midrange speaker ? , If so can I use 2 of them wired in parallel ? I'm trying to increase the midrange some , the highs and lows sound great. Both networks used similar coils and caps. 3.9 ohm on the dual midrange and 4 ohm on the single midrange.
Click to expand...

You could sub the 9.9 with the 7 Ohms, but you will need to modify the x-over, same if you paralleled the mid drive. You could download simulation software (free) and simulate see what happens.
 
The speakers are done and they sound pretty good up around 20 Watts with the bass set flat and the treble set at minus 1 , just a tenge trebelly overall . The four Sansaui 5 inch midrange speakers (2 per side) do not like any more power then aboit 20 Watts , rated at 40 ? - but they do offer up a crisp voice even though they are a bit strained (I think ) , I think those four speakers should be replaced , with something a little bit better before they self destruct ! . I closed up the air holes completely , I like solid cabinets. The horns stuck up a little bit so I need to caulk around them later on when I replace the 4 midrange speakers. They sound pretty good overall , but there not like EVs , JBLs , Eminence or Celestron's ! , About like vintage Jensen and that's is all I expected to get out of them to begin with. I was wondering if the expensive caps I used on the midrange was a mistake or not ? The old caps were more tame and suttle ! , In parallel it should not change the sound very much with a 2 ohm dirrerance , so it must be the cap blasting the midrange ! . I used to set the treble 1 positive now it is 1 negative , could a by pass resistor be added to the cap to tame it down a little bit ? Or to ground ? , I think 2 - 8 ohm mids or two 4 ohm mids in series would help my situation on each speaker. They sound OK in the room there in , I just think I can improve them some. This speaker project turned out pretty good. Thanks for the advice , weather I used it or not ? . I know that I can go buy myself some good used speakers for cheap at a pawn shop but that doesn't teach me anything except to throw money at my problems ! , To me ; Any sinner can do that ! . Now on to my overheating power supply !
 
A small value resistor in series will attenuate the sound and lower the crossover frequency. A higher value resistor in parallel will attenuate the sound increase the crossover frequency. one in series and one in parallel is an L-Pad. Looks like you have an adjustable l pad so what is adding a resistor going to do? Did it control the Mids or just the super tweeters
 
phansen39 said:
A small value resistor in series will attenuate the sound and lower the crossover frequency. A higher value resistor in parallel will attenuate the sound increase the crossover frequency. one in series and one in parallel is an L-Pad. Looks like you have adjustable l pads so what is adding a resistor going to do?
Click to expand...
I did not use the adjustable Sansaui , I used the fixed Magnavox set up instead. A single coil and single cap . How small a resistor in series ?
 
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