The 5.25" speakers are too small to be woofers and have low sensitivity.
The 6.5" woofer also has low sensitivity.

The crossovers in the manual have the inductances of the coils.
I doubt if you can buy the coils.

Use a power amplifier for each speaker and make an active crossover with opamps (no coils).

I have a subwoofer in the trunk and am using the other 2 sets of speakers for the mids and highs. That's why I want to make sure that the SPX-137R and the SPX-177R are cut off above 700Hz so that the bass tones don't blow them. The other settings that are determined by the fuse jumpers (for lack of the correct term) are used to set upper cutoff freq. so that the highs come out the tweeters ans the mid-range frq come out where they are supposed to.

 

Hmm, I don't think that standard fuses are 1/4" in diameter. Trying to cram a standard 1/4" pot shaft into the fuseholder/jumper would probably damage them. Seems to me that AWG 4 solid copper wire might be a close match, but I don't know where my spouse hid my digital calipers at the moment, so I can't check.

Many older pot shafts were made of brass. They would have 4.8 times the resistance of copper. Newer pot shafts seem to be made from aluminum; they're about 1.55 times the resistance of copper, but have a nagging tendency to return to their natural state (bauxite, a white powder) that does not conduct electricity well at all.

The jumpers were gold plated to eliminate the corrosion problem. Internally, they were most probably solid copper.

We have a local metal shop here in town and I can get a few different types of solid core wire or cylinder - so what would be the best material to use? I am thinking that 4g solid wire would be best because of what you stated above.

Man YOU GUYS ROCK!!!!!!!!!!!!!

 

Correct instructions for inductors from manual (value and wire gauge)

Identical cores, Look like what is shown in your photo: 3/4" inside diameter, 1/2" tall, 18ga Enameled Wire:

0.10mH - 72 turns, 16.5 ft wire, Est Resistance 0.12 Ohms

0.18mH - 95 turns, 23.5 ft wire, Est Resistance 0.16 Ohms

0.25mH - 110 turns, 28 ft of wire, Est Resistance 0.20 Ohms

0.32mH - 123 turns, 32.5 ft of wire, Est Resistance 0.23 Ohms


Again, the 1.5Ω/10W Resistor should be mounted above the board about 1/2" for air circulation, the bottom side of the board is discolored due to that resistor overheating.

Just from your suggestion I will plan to elevate all of the resistors off the board.

 

We have a local metal shop here in town and I can get a few different types of solid core wire or cylinder - so what would be the best material to use? I am thinking that 4g solid wire would be best because of what you stated above.

OK, just got back from checking a few standard fuses (mil-spec, in fact)
They actually ARE 1/4 inch in diameter. My apologies for the confusion.

The closest AWG to 1/4" is 2, but it's 0.00076" oversized (.76/1000 inch)

You would likely be better off to simply get some 1/4" round copper stock, and have it cut to length.

 

Correct instructions for inductors from manual (value and wire gauge)

Identical cores, Look like what is shown in your photo: 3/4" inside diameter, 1/2" tall, 18ga Enameled Wire:

0.10mH - 72 turns, 16.5 ft wire, Est Resistance 0.12 Ohms

0.18mH - 95 turns, 23.5 ft wire, Est Resistance 0.16 Ohms

0.25mH - 110 turns, 28 ft of wire, Est Resistance 0.20 Ohms

0.32mH - 123 turns, 32.5 ft of wire, Est Resistance 0.23 Ohms

How come the layout shows only 2 inductors (2 big coils) but the schematic shows 4? 0.10mH, 0.18mH, 0.25mH and 0.32mH

Also the schematic shows caps of 5.6uF, 12uF and 8.2uF and the board shows (the 5.6 and the 12uF OK) but then there is the 22uF and not an 8.2uF?

The resistor setup is also confusing. Schematic shows 1.0ohm, 2.2ohm, 1.5ohm and a 6.8ohm and the board shows a 4.7, 15, 1.5 (X2), 0.5, 3.3, 5.6 ones?

 

The different values would be for different frequency cutoffs, or different speakers, 4 or 8 ohm, or combinations of 4 or 8 ohm in parallel or even series.

I calculated above for 8 ohm, and came up with 0.15mH for 3800Hz using the caps that were jumpered in on the board in the photo.

 

The different values would be for different frequency cutoffs, or different speakers, 4 or 8 ohm, or combinations of 4 or 8 ohm in parallel or even series.

I calculated above for 8 ohm, and came up with 0.15mH for 3800Hz using the caps that were jumpered in on the board in the photo.

So which coil winding would I use to make the 2 that are attached to the board. Using 18g or 20g how many windings and what size bobbin or plastic roller etc....

 

18ga enamel coated wire would give you the best power handling, and still easy to wind. One source I found, you can get multiple colors http://www.parawire.com/18gaugemagnetwire.shtml

Any "magnetically inert" insulating material will work for the core, such as the empty spool from hookup wire, A piece of 3/4" PVC pipe with some flat pieces glued to either side to hold the windings in place, etc. The 3/4" inside diameter and 1/2" tall/wide IS IMPORTANT. If it is smaller, the inductance will be too low, if it is larger, you will run out of wire if pre-cut, and the inductance will be higher. within 1/8" is OK, windings will be between 1/4" and 1/2" deep in layers, try to lay them on neatly, the larger gauge wire will help a lot in that area.

I'd suggest 0.25mH, and the 0.18mH. Those seem to match what is in the existing one you are duplicating the best. Not because I want to make your fingers tired.

 

I'd suggest 0.25mH, and the 0.18mH. Those seem to match what is in the existing one you are duplicating the best. Not because I want to make your fingers tired.

Why does the schematic show 4 of the coils when I can only see 2 of them on the board?

 

They are selectable by a jumper, the model you show above doesn't have as many options as the full schematic allows for.

It is common for manufacturers to do this, then change the model number, or add a letter to the same model number. Once a PC Board is designed and built, all of them need to be used, the fab cost is too high to simply throw them out.

Example: Engineers designed circuit schematic to hold 4 options. The marketing design group, who have no clue how big an inductor is, designed an enclosure where only 2 would actually fit in the case, and ordered a huge batch to be machined/extruded. Rather than have either group start over, the PCB was made to fit the most common choices. Sometimes this happens in reverse as well.

 

They are selectable by a jumper, the model you show above doesn't have as many options as the full schematic allows for.

It is common for manufacturers to do this, then change the model number, or add a letter to the same model number. Once a PC Board is designed and built, all of them need to be used, the fab cost is too high to simply throw them out.

Example: Engineers designed circuit schematic to hold 4 options. The marketing design group, who have no clue how big an inductor is, designed an enclosure where only 2 would actually fit in the case, and ordered a huge batch to be machined/extruded. Rather than have either group start over, the PCB was made to fit the most common choices. Sometimes this happens in reverse as well.

That explains a lot thanks. Much appreciated.

Bill

 

I have a subwoofer in the trunk and am using the other 2 sets of speakers for the mids and highs. That's why I want to make sure that the SPX-137R and the SPX-177R are cut off above 700Hz so that the bass tones don't blow them. The other settings that are determined by the fuse jumpers (for lack of the correct term) are used to set upper cutoff freq. so that the highs come out the tweeters ans the mid-range frq come out where they are supposed to.

The SPX-137R are a 2-way set of low power speakers with a little 5.5" woofer. Its free-air resonance is 53Hz.
The SPX-177R is a low power little 6.5" woofer. Its free-air resonance is 42hz.
We don't know what size, power rating and resonance is your subwoofer.

The subwoofer should have a lowpass crossover at about 150Hz. The other speakers should have a highpass crossover at 150Hz, not 700Hz.

 

The SPX-137R are a 2-way set of low power speakers with a little 5.5" woofer. Its free-air resonance is 53Hz.
The SPX-177R is a low power little 6.5" woofer. Its free-air resonance is 42hz.
We don't know what size, power rating and resonance is your subwoofer.

The subwoofer should have a lowpass crossover at about 150Hz. The other speakers should have a highpass crossover at 150Hz, not 700Hz.

OK 150Hz it is. My sub has its own amp with built in crossover.

 

18ga wire has an RMS ability of around 300W with the size of inductors above.

Was 700 and 3800 still the two cutoffs? Keep in mind those are dependent on the capacitance shown as jumped in your photo.

 

18ga wire has an RMS ability of around 300W with the size of inductors above.

Was 700 and 3800 still the two cutoffs? Keep in mind those are dependent on the capacitance shown as jumped in your photo.

Yes 3800 for the tweeter and 700 for the mid

 

I thought the frequencies seemed odd, but ignored it. I've been following original question of duplicating the existing schematic, and knowing 700 and 3800 were desired cutoffs. I now stopped to look at the full system, and I'm confused as well... It's missing 2 octaves somewhere.

150Hz 24dB/octave Active LP on amp for sub.

6dB-12dB/octave passive crossovers for Midrange and tweeter, tweeter is 3800+ Highpass, Midrange is 700Hz Lowpass

Which driver is covering the two octaves between 750Hz and 3k? Or, between 200 and 800Hz if Midrange is configured as highpass? The Crossover doesn't have a bandpass, only lowpass and highpass.

 

I thought the frequencies seemed odd, but ignored it. I've been following original question of duplicating the existing schematic, and knowing 700 and 3800 were desired cutoffs. I now stopped to look at the full system, and I'm confused as well... It's missing 2 octaves somewhere.

150Hz 24dB/octave Active LP on amp for sub.

6dB-12dB/octave passive crossovers for Midrange and tweeter, tweeter is 3800+ Highpass, Midrange is 700Hz Lowpass

Which driver is covering the two octaves between 750Hz and 3k? Or, between 200 and 800Hz if Midrange is configured as highpass? The Crossover doesn't have a bandpass, only lowpass and highpass.

Not confused just misinformed. There is no sub connected on this crossover.

Basically, I want the tweeter to get only sounds above 3800 and nothing else. I want the mid range to get everything above 700 and nothing else. The sub is totally separate and on another amp that has its own crossover built into the amp.

 

This crossover has one lowpass and one highpass.

You are looking for two highpass filters.

In addition, vocals will sound very weak/tinny if the 500Hz range isn't covered well.

 

This crossover has one lowpass and one highpass.

You are looking for two highpass filters.

In addition, vocals will sound very weak/tinny if the 500Hz range isn't covered well.

Basically that is what I need but the the lower crossover needs to be a highpass set really low just to knock out the bass, so it will cover the 500Hz range. I guess you would call this a midpass. I just don't want the lower bass coming thru anywhere on this portion of the system.

 

This isn't the crossover you are looking for, then.

You need to design one with a highpass or bandbass for midrange, and a highpass for the tweeters.