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Vintage Bagend AF 1 (1985) help ...

Jerseydeadhead

Jerseydeadhead

Guest
Apr 6, 2017
106
114
#1
I have an old bag end cab from the mid 80s, it's gigantic and heavy as hell but holy poopie does it sound amazing!

Anyway I had someone from BAGEND send me some old spec sheets cause I had a feeling the specs I got from the seller were a little bit off and I attached them to this post .

What i'm confused about is the crossover system. The way I was told it works is as follows . If you plug into the left input the signal goes full range to all 3 speakers. If also plug into the second input whatever is sent through that input goes directly to the 18" speaker while the other input gets sent to the 12" + horn.

Now what i'm confused about is it looks like in the specs there's a built in crossover in front of the 12" + horn. But im not very good at reading at specs so i'm not sure what i'm looking at lol. Anyway I was told to use an external crossover before plugging into the cab if I wanted to use both inputs, but it seems like to me there is already a crossover inside the cab?

If anyone could check out this spec sheet and help me make sense of it I would greatly appreciate it !
 

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#2
Jerseydeadhead said:
I have an old bag end cab from the mid 80s, it's gigantic and heavy as hell but holy poopie does it sound amazing!

Anyway I had someone from BAGEND send me some old spec sheets cause I had a feeling the specs I got from the seller were a little bit off and I attached them to this post .

What i'm confused about is the crossover system. The way I was told it works is as follows . If you plug into the left input the signal goes full range to all 3 speakers. If also plug into the second input whatever is sent through that input goes directly to the 18" speaker while the other input gets sent to the 12" + horn.

Now what i'm confused about is it looks like in the specs there's a built in crossover in front of the 12" + horn. But im not very good at reading at specs so i'm not sure what i'm looking at lol. Anyway I was told to use an external crossover before plugging into the cab if I wanted to use both inputs, but it seems like to me there is already a crossover inside the cab?

If anyone could check out this spec sheet and help me make sense of it I would greatly appreciate it !
Click to expand...

At first blush the 12+ horn crossover appears to be between the 12 and the horn, not in front of both. But it's not clear whether the 12 is high passed or not, which the printed specs imply to be so. In any case, just wire it as you were told.
 
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#4
Jerseydeadhead said:
Okay so I would use an external cross over. Let's say I set it at 120hz plug the high into input 1 and the lows to input 2. The low is sent straight to the 18 and the high will get split between the horn and 12" ?
Click to expand...

Yep, but of course you need two power amps between the crossover and the two cab inputs.
 
#7
Jerseydeadhead said:
If you plug into the left input the signal goes full range to all 3 speakers. If also plug into the second input whatever is sent through that input goes directly to the 18" speaker while the other input gets sent to the 12" + horn.

Now what i'm confused about is it looks like in the specs there's a built in crossover in front of the 12" + horn. I was told to use an external crossover before plugging into the cab if I wanted to use both inputs, but it seems like to me there is already a crossover inside the cab?
Click to expand...

Notice the switching in the jack circled in red. When nothing is plugged into this jack, the 18 is connected to the other input jack on one side and the box labeled LF-Coil AFX-LO on the other. This box should be some sort of Low Pass Filter network (I believe from the specs its' intended to form a time-aligned 125 hz effective crossover. A high pass is not used on the 12 because the driver is in a small sealer chamber.

When you plug into the switching jack, the 18 is disconnected from box labeled LF-Coil AFX-LO and also from other jack. This isolates the 18 from the rest of the circuitry so you can safely biamp the 18 and 12+horn.
upload_2018-6-1_12-5-41.png


So both of the statements I left in your quote are true. If you want to properly biamp, you need a crossover. I would start with it set at 125 hz and fiddle around to see if you like it set anywhere between 125hz and about 250hz.
 
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#9
Wasnex said:
Notice the switching in the jack circled in red. When nothing is plugged into this jack, the 18 is connected to the other input jack on one side and the box labeled LF-Coil AFX-LO on the other. This box should be some sort of Low Pass Filter network (I believe from the specs its' intended to form a time-aligned 125 hz effective crossover. A high pass is not used on the 12 because the driver is in a small sealer chamber.

When you plug into the switching jack, the 18 is disconnected from box labeled LF-Coil AFX-LO and also from other jack. This isolates the 18 from the rest of the circuitry so you can safely biamp the 18 and 12+horn.
View attachment 3035619

So both of the statements I left in your quote are true. If you want to properly biamp, you need a crossover. I would start with it set at 125 hz and fiddle around to see if you like it set anywhere between 125hz and about 250hz.
Click to expand...


Awesome, thank you for the info. It's a weird cab but it's my baby. I've only used the crossover with it once and had it set at 100hz, I'll try it alittle higher next time!
 
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#12
Jerseydeadhead said:
Interesting... I can bridge my power amp and run the cab full range through one input but that bumps my wattage to 400w.
Click to expand...

Is the amp safe bridged into 4 ohms? If yes, try it both bridged and biamped and choose the one that best meets your needs. A bit of caution is warranted as I believe 400 watts exceeds the continuous, but not the peak power handling of the design.

With biamping, I would suggest experimenting with running the crossover frequency even higher than 250hz, just for fun. You will probably be surprised by the tonal variety this gives you. Depending upon the design of your crossover, you may need to flip the polarity of one channel for best phase response. Sometimes a polarity or phase switch is built into the crossover to make this easy. My old Bag End S15 had a banana plug, so I just flipped the plug when I biamped with an old GK 800RB.
 
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#13
Wasnex said:
Is the amp safe bridged into 4 ohms? If yes, try it both bridged and biamped and choose the one that best meets your needs. A bit of caution is warranted as I believe 400 watts exceeds the continuous, but not the peak power handling of the design.

With biamping, I would suggest experimenting with running the crossover frequency even higher than 250hz, just for fun. You will probably be surprised by the tonal variety this gives you. Depending upon the design of your crossover, you may need to flip the polarity of one channel for best phase response. Sometimes a polarity or phase switch is built into the crossover to make this easy. My old Bag End S15 had a banana plug, so I just flipped the plug when I biamped with an old GK 800RB.
Click to expand...

Actually after double checking the power amp specs looks like bridge-mono into 4ohms bumps me up to 500w! 8ohm stereo is 145w per channel. So looks like I need to get a different power amp or stick to bi-amping because 145w is underpowered for a 300w full range. When you bi amp it brings the wattage down to 200w
 
#14
Jerseydeadhead said:
Actually after double checking the power amp specs looks like bridge-mono into 4ohms bumps me up to 500w! 8ohm stereo is 145w per channel. So looks like I need to get a different power amp or stick to bi-amping because 145w is underpowered for a 300w full range. When you bi amp it brings the wattage down to 200w
Click to expand...

IMHO, either way should be fine as long as it meets your needs and you pay attention. Feeding the speaker 500W continuous would probably be a bad idea, but it will easily take 500 watt peaks according to the spec sheet. Given you say 145W seems loud, I doubt you will ever need need that much power, but having additional headroom can provide better tone and feel....but this subjectively depends upon your goals, which is why I suggest trying both ways.
 
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#15
Wasnex said:
IMHO, either way should be fine as long as it meets your needs and you pay attention. Feeding the speaker 500W continuous would probably be a bad idea, but it will easily take 500 watt peaks according to the spec sheet. Given you say 145W seems loud, I doubt you will ever need need that much power, but having additional headroom can provide better tone and feel....but this subjectively depends upon your goals, which is why I suggest trying both ways.
Click to expand...

Right on. After all this info I can't wait to get home and mess around with this thing
 
#16
Jerseydeadhead said:
Actually after double checking the power amp specs looks like bridge-mono into 4ohms bumps me up to 500w! 8ohm stereo is 145w per channel. So looks like I need to get a different power amp or stick to bi-amping because 145w is underpowered for a 300w full range. When you bi amp it brings the wattage down to 200w
Click to expand...

One reason biamping has fallen out of favor is that inherent mismatch when using typical stereo power amps. Using a complementary mismatch of driver impedances can mitigate that some, but that doesn't seem to have been a very popular approach.
 
#17
Bag End for life! (Or Marshall 1990 8x10... for the mojo)
Just have to chime in about bag End, 4x12, 1x8, 1x15 are tops. But the bag End enclosed 2x10 is my favourite cabinet ever made for low end.

#RambleOn
 

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