JBL A180 Tower Speaker Review

[Dennis Murphy]

I'm very, very pleased with the sound of A180 mod. After side by side listening of my A170 and A180 mod I made A180 mod front speakers and A170 surround ones.
@Dennis Murphy, you're a legend!

Anybody my age is a legend. But I'm glad you like the results.

 

[Azatto]

Just measured inductanses of the stock filter and here is updated schematic.

 

[MickeyBoy]

Apologies, don't know what happened there.

Here is the list with links:

- Crossover PC Board 2-Way 12 dB
$3.99
Quantity: 4
Total Amount: $15.96

- Dayton Audio DNR-1.0 1 Ohm 10W Precision Audio Grade Resistor
$1.49
Quantity: 2
Total Amount: $2.98

- Dayton Audio IC181 1.0mH 18 AWG Laminated Iron Core Inductor
Quantity: 2
Total Amount: $14.98

- Dayton Audio DMPC-15 15uF 250V Polypropylene Capacitor
$6.81
Quantity: 2
Total Amount: $13.62

- Dayton Audio DPR10-2.4 2.4 Ohm 10 Watt Precision 1% Audio Grade Resistor
$1.79
Quantity: 2
Total Amount: $3.58

- Jantzen Audio 3.9uF 400V Z-Standard Capacitor
$3.88
Quantity: 2
Total Amount: $7.76

- Dayton Audio DMPC-4.7 4.7uF 250V Polypropylene Capacitor
$3.29
Quantity: 2
Total Amount: $6.58

- Dayton Audio DMPC-10 10uF 250V Polypropylene Capacitor
$5.48
Quantity: 2
Total Amount: $10.96

- Dayton Audio 0.27mH 18 AWG Perfect Layer Inductor Crossover Coil
$4.89
Quantity: 2
Total Amount: $11.58

- Dayton Audio 0.10mH 20 AWG Air Core Inductor Crossover Coil
$2.89
Quantity: 2
Total Amount: $6.78

- Dayton Audio DPR10-20.0 20 Ohm 10 Watt Precision 1% Audio Grade Resistor
$1.79
Quantity: 2
Total Amount: $3.58

Many thanks, Alex. Alas, the 1.0 mH inductor is out of stock at Parts Express until October. Haven't figured a practical way around this.

 

[375HP2482]

The values for the Bottom Woofer correlate to a 1.0 kHz Butterworth LPF.

I'm thinking that most of the excessive measured distortion around 1.3 kHz may be coming from the tweeter, which is crossed over too low for a 2-pole filter (C-L). If so, then adding another pole (C-L-C) would reduce that significantly.

I always used 3-pole filters on tweeters and AMT units, along with a Polyswitch at the filter input. At the time we were paying around ten cents per microfarad for film capacitors, so not a big deal -- the Polyswitch was typically fifty cents.

 

[375HP2482]

Many thanks, Alex. Alas, the 1.0 mH inductor is out of stock at Parts Express until October. Haven't figured a practical way around this.

You could use two 2.0 mH and parallel them.

Or use the 20-gauge air core version, which would reduce level by 0.5 dB relative to the 1.0 mH iron core.

 

[Dennis Murphy]

The values for the Bottom Woofer correlate to a 1.0 kHz Butterworth LPF.

I'm thinking that most of the excessive measured distortion around 1.3 kHz may be coming from the tweeter, which is crossed over too low for a 2-pole filter (C-L). If so, then adding another pole (C-L-C) would reduce that significantly.

I always used 3-pole filters on tweeters and AMT units, along with a Polyswitch at the filter input. At the time we were paying around ten cents per microfarad for film capacitors, so not a big deal -- the Polyswitch was typically fifty cents.

I checked that out and it's not the tweeter. The distortion is just as high without the tweeter running. It's breakup from the upper woofer. (See posts 74 and 98).
BTW, I transplanted the components on my test board to a much longer and thinner board that would fit through the rear input terminal opening. That means I can ship my single modded 180 to Amir if he wants to measure it. I wouldn't need it back. it's Amir's call. I know he's really busy.

 

[MickeyBoy]

You could use two 2.0 mH and parallel them.

Or use the 20-gauge air core version, which would reduce level by 0.5 dB relative to the 1.0 mH iron core.

Thanks. I'll have to parallel two and figure out later how to orient them on the board to minimize unwanted interaction.

 

[375HP2482]

The two coils should be mounted with their iron cores pointing at right angles and/or separated on the board. Using two coils in parallel quadruples the power capacity while halving the resistance.

It wouldn't hurt to insert an RXE065F Polyswitch in series with the input of the HF filter. They are Back Ordered at Parts Express but Mouser has them. For use in Karaoke go with RXE050F.

 

[MickeyBoy]

The two coils should be mounted with their iron cores pointing at right angles and/or separated on the board. Using two coils in parallel quadruples the power capacity while halving the resistance.

It wouldn't hurt to insert an RXE065F Polyswitch in series with the input of the HF filter. They are Back Ordered at Parts Express but Mouser has them. For use in Karaoke go with RXE050F.

Many thanks for the advice about mounting the inductors in a T pattern. But now you've thrown in something I am unfamiliar with: a polyswitch. More research ahead.

 

[375HP2482]

A polyswitch is a conductive skin on a heat-sensitive membrane that, when heated from excessive current, expands and separates the conduction regions, drastically reducing conduction (increasing resistance). This reduces the passthrough current significantly, protecting any downstream devices of limited power capacity. Once the applied voltage has been reduced, the device contracts sufficiently to bring the conductive regions back in contact. The thermal time constant of this action is lower (quicker to respond and reset) with the smaller polyswitches (physically smaller/lower current), which is appropriate for fragile devices like tweeters.

 

[MickeyBoy]

A polyswitch is a conductive skin on a heat-sensitive membrane that, when heated from excessive current, expands and separates the conduction regions, drastically reducing conduction (increasing resistance). This reduces the passthrough current significantly, protecting any downstream devices of limited power capacity. Once the applied voltage has been reduced, the device contracts sufficiently to bring the conductive regions back in contact. The thermal time constant of this action is lower (quicker to respond and reset) with the smaller polyswitches (physically smaller/lower current), which is appropriate for fragile devices like tweeters.

Whew - so like a fuse that resets itself. I am about to put a cap transplant and new binding posts on a pair of old Infinity Qe speakers and have been stumped by the fuse. Now you have given me the answer. Many. many thanks, as usual.

 

[375HP2482]

Polyswitches were developed by the Raychem Corporation, who also invented heat-shrinkable tubing and the touchscreen. Polyswitches were part of the Circuit Protection Group at Raychem, which was split off and bought by Littelfuse Corp.

 

[Head_Unit]

This is a 2.5-way design with upper woofer

What size are the woofers? It's hard to tell from pictures sometimes. That would be my review request, to list woofer size. (And if not too much trouble the cabinet size)

 

[375HP2482]

Woofer and cabinet sizes are widely available.

 

[MickeyBoy]

What size are the woofers? It's hard to tell from pictures sometimes. That would be my review request, to list woofer size. (And if not too much trouble the cabinet size)

Yes, this info is widely available. But I'll give it anyway. The woofers are nominal 6.5" and measure 5.5" edge of surround to edge. The cabinets are 11.5" deep. 9" wide, and 41" high, not counting the legs which raise the box about 1.75" off the ground.

 

[Head_Unit]

Woofer and cabinet sizes are widely available.

Yes, this info is widely available.

It's just much more convenient if @amirm can just type that at the start of the review as a quick reference. It's quicker than Googling a model number, then paging through to see the information (and sometimes manufacturer dimensions it is not clear if footers are included). First world problems, I know. And some degree of laziness, mea culpa [breast beating emoji]

 

[Erici]

It's just much more convenient if @amirm can just type that at the start of the review as a quick reference. It's quicker than Googling a model number, then paging through to see the information (and sometimes manufacturer dimensions it is not clear if footers are included). First world problems, I know. And some degree of laziness, mea culpa [breast beating emoji]

So you would rather have Amir add commonly available information to each review rather than complete more reviews? That's not a very good idea.

 

[Presently42]

So you would rather have Amir add commonly available information to each review rather than complete more reviews? That's not a very good idea.

To play devil's advocate, if the information is so commonly available, searching for (if indeed it even needs searching for) and including it in a review will take a trivial amount of time; and in no way preclude further reviews being made

 

[tw 2022]

To play devil's advocate, if the information is so commonly available, searching for (if indeed it even needs searching for) and including it in a review will take a trivial amount of time; and in no way preclude further reviews being made

Ditto...

 

[Head_Unit]

So you would rather have Amir add commonly available information to each review rather than complete more reviews? That's not a very good idea.

Oh my god I don't think it would take long to type "two six inch woofers" eh? To provide some context, since it's hard to tell sometimes. If it's too time consuming to take out a tape measure, yeah that can be looked up although as I noted manufacturers' dimensions are not always clear.