Question about Avatar SB112 midrange mod

[babsobass]

Quick question for the cab experts out there. I recently modified an Avatar SB112 to replace the horn tweeter with an Eminence ALPHA-6CBMRA sealed-back midrange. I also replaced the Avatar crossover with an Eminence PXB:1K6 (crossed at 1.6KHz). And while at it I replaced the L-pad, which was fairly low wattage, with a 100W, 8ohm unit. I got most of my info from this thread:

https://www.talkbass.com/threads/need-help-wiring-replacement-high-pass-filter-for-avatar-cabinet-mod.924361/

The wiring I used looks like this:

So, to the issue. When I rotate the L-pad all the way in either direction, I still get sound out of the mid. In fact rotating the L-pad seems to have no effect. Obviously, I was expecting that all the way in one of the two directions would kill all sound from the mid.

I have yet to re-confirm all the wiring to ensure that it matches the diagram, but I wanted to check that the diagram is sound. Does the wiring diagram look good for this simple 2-way topology? My thought was that I might have the terminals on the L-pad wrong. The idea is that the midrange would be “grounded” (to in -) when turning all the way in one direction. (Ignore the IN-OUT-GND designation on the terminals, it was my guess - I don't believe the terminals are labeled)

Thanks ahead of time for your comments.

 

[jeff7bass]

Above my knowledge level but is it stuck full on or somewhere in-between? How does it sound?

 

[daveman50]

Cool beans!
That was my old thread - the correct link is:
Need help wiring replacement high-pass filter for Avatar cabinet mod
I didn't use the l-pad and have never missed it.
I still use the cab. It's still great. (A little heavy but not terrible.)

 

[babsobass]

Cool beans!
That was my old thread - the correct link is:
Need help wiring replacement high-pass filter for Avatar cabinet mod
I didn't use the l-pad and have never missed it.
I still use the cab. It's still great. (A little heavy but not terrible.)

It's all you, man.. I mean daveman! I did fix the problem (which I will post in a minute). But the core of this mod was taken straight from your thread.

 

[babsobass]

Ok, sometimes reading the instructions is the right thing to do!

The issue was, as I suspected, with the wiring of the L-pad. Instead of the L-pad sweeping between the crossover T+ and IN- as shown in the diagram above, it needs to sweep between both crossover outputs (T+ and T-). This was detailed in a little PDF available at the site I bought the L-pad. After a single wire change the midrange control works as it should. The updated wiring diagram is below.

 

[babsobass]

Above my knowledge level but is it stuck full on or somewhere in-between? How does it sound?

As I said above, this issue is now fixed.

As far as the mod itself, I really like the results. I was hoping that the midrange would be a little less harsh, and better compliment the frequency range of the woofer. I think this is what I got. I'll be gigging the mod this Friday for the first time. That'll be the real test.

 

[daveman50]

Very nice. Which l-pad are you using?

 

[daveman50]

It's all you, man.. I mean daveman! I did fix the problem (which I will post in a minute). But the core of this mod was taken straight from your thread.

This is why I love Talkbass. My original post was 9 years ago.
It's a massive knowledge base, a mega-brain for bassists!

 

[babsobass]

Very nice. Which l-pad are you using?

I used one from Parts Express, I think it's this one:

Home

 

[daveman50]

I used one from Parts Express, I think it's this one:

Home

thanks

 

[agedhorse]

Just note (for those not aware) that L-Pads are typically rated at 8 times the rated audio power, so a 100W L-Pad is really about 12-13 watts continuous. This is because audio signals are typically averaged to 1/8 rated power due to the dynamics present in typical music.

It’s similar to tweeters often being rated at a silly high number when in fact the rating actually means that it’s suitable when crossed over for a system of that rated power (on a good day).

 

[babsobass]

Just note (for those not aware) that L-Pads are typically rated at 8 times the rated audio power, so a 100W L-Pad is really about 12-13 watts continuous. This is because audio signals are typically averaged to 1/8 rated power due to the dynamics present in typical music.

It’s similar to tweeters often being rated at a silly high number when in fact the rating actually means that it’s suitable when crossed over for a system of that rated power (on a good day).

So Andy, how do I use that information? The SB112, as shipped to me, is rated at 250W. I assume that most of that wattage is absorbed by the woofer. I replaced the stock crossover and tweeter with a 1.6KHz crossover and a midrange. At that cross over frequency I feel that a 100W L-pad is sufficient (the L-pad replaced is rated at 15W!). Does that sound reasonable?

 

[agedhorse]

For bass guitar crossed at 1.6kHz, it should be fine. The 100W rating for tweeter use is also derated by the relative power per octave. On bass guitar, the power above 1.6kHz is quite low unless using heavy distortion.