Vintage Peavey "Bi-Amping" Question

[Obese Chess]

Hi all,

On my constant quest to disrespect my own back - sort of a carrot-and-stick situation balancing my two loves, playing bass and powerlifting - I have recently picked up a Peavey Bass MkIV and a Peavey 1820 cabinet - the cabinet is a single 18 and two 10s.

The cabinet has inputs on the back for both "full range" and "Bi-Amp: high/low" as shown in this thread: https://www.talkbass.com/threads/peavey-1820-cab-actually-2-ohms.1211870/

The head also has crossover/bi-amp outputs.

My thought is that the design is such that I can split the frequencies and send the lows to the 18s and the highs to the 20s, but I don't really understand how this is done. The manual only sort of describes how to do this when using an external power amp, which I am not using:

or how to use the crossover outputs as an effects loop, which i am also not doing. Peavey's customer service was unfortunately useless when I asked them this, telling me to consult a techinician.

Talkbass counts as technicians, right?

So, how do I set this up for the best results?

Thanks!

 

[Stylee Mousse]

The crossover outputs are line level, I.e. need to go to a power amp channel (one per output) which then they go to the speaker biamp inputs.

Ok - I see then you can use the internal amp for one of the crossed frequencies via the power amp in input. So you just need one extra amp channel to biamp


I’d just run it full range and see what you get. It should be plenty loud

 

[Michedelic]

Hi all,

On my constant quest to disrespect my own back - sort of a carrot-and-stick situation balancing my two loves, playing bass and powerlifting - I have recently picked up a Peavey Bass MkIV and a Peavey 1820 cabinet - the cabinet is a single 18 and two 10s.

The cabinet has inputs on the back for both "full range" and "Bi-Amp: high/low" as shown in this thread: https://www.talkbass.com/threads/peavey-1820-cab-actually-2-ohms.1211870/

The head also has crossover/bi-amp outputs.

My thought is that the design is such that I can split the frequencies and send the lows to the 18s and the highs to the 20s, but I don't really understand how this is done. The manual only sort of describes how to do this when using an external power amp, which I am not using:
View attachment 7128325

or how to use the crossover outputs as an effects loop, which i am also not doing. Peavey's customer service was unfortunately useless when I asked them this, telling me to consult a techinician.

Talkbass counts as technicians, right?

So, how do I set this up for the best results?

Thanks!

I’ll skip the bi-amp shaming, there will be plenty of that otherwise, but I would have to ask, why all that clunky old Peavey gear? The amp(s) will give you enough of a workout. If I was going to go this route(again), I’d at least use separate lightweight modern cabs.

Anyway…that amp has a single channel power section, correct? Yes, you will need to acquire an additional power amp unit in order to have the proper bi-amp set up. Within your amp, the signal is sent(after the preamp)to an internal crossover, which splits the signal so that the highs are filtered out on one side, and the lows attenuated on the other. Which side gets assigned to your on-board mono power section, I’m not sure how that gets done, but what’s left over would go to an auxiliary outboard mono power amp, and then to the appropriate driver(s).

 

[Obese Chess]

I’ll skip the bi-amp shaming, there will be plenty of that otherwise, but I would have to ask, why all that clunky old Peavey gear? The amp(s) will give you enough of a workout. If I was going to go this route(again), I’d at least use separate lightweight modern cabs.

Anyway…that amp has a single channel power section, correct? Yes, you will need to acquire an additional power amp unit in order to have the proper bi-amp set up. Within your amp, the signal is sent(after the preamp)to an internal crossover, which splits the signal so that the highs are filtered out on one side, and the lows attenuated on the other. Which side gets assigned to your on-board mono power section, I’m not sure how that gets done, but what’s left over would go to an auxiliary outboard mono power amp, and then to the appropriate driver(s).

1. I love how it sounds, I'm strong enough to carry it, I don't bring the cabinet to shows anyway (I just run direct from the head) and the entire rig was $200.
2. That makes sense, I believe it does have a single channel power section but I don't know how I'd confirm this. I was basically thinking the internal crossover section would send the lows to one set of speakers and the highs to another, but basically it sounds like you're saying it will do that but you need to independently power both splits, thus the need for another power amp.

 

[WayneP]

I used to have a Mark IV back in the ’80s – loved it. It’s a mono amplifier. As already mentioned, you’ll need a second (basic power) amp if you want to biamp the 1820cabinet.

With bi-amplifying, an electronic crossover is needed to separate the high frequencies from the low, sending the high and low signals to different amplifiers that will drive the speakers designated as high frequency (the 10" speakers in this case), and low frequency (the 18s). Often the electronic crossover is a stand-along unit. However, the Mark IV has this feature built-in, so an outboard device is not needed.

All you need to do is run a jumper cable between the Mark IV’s “Crossover High Out” jack to the “Power Amp Input” jack. Connect the Mark IV’s back-panel speaker output to the “Bi Amp Hi” jack on the 1820. What you’ll have then is the Mark IV powering the two 10” speakers (i.e. the highs) in the 1820 cabinet.

Back at the Mark IV, run a cable from the “Crossover Lo Out” to the input of your second amp, and connect it’s speaker output to the 1820’s “Biamp Low” jack. Bingo, you now have a bi-amplified speaker.

Next, adjust the Mark IV’s “Crossover” knob to where you want it set. This is what determines which frequencies go to the “high” speakers, vs. the “low” speakers. You probably want to set it somewhere between 100-175 (Hz). So, everything from 100-175 Hz and up goes to the high (10") speakers, and everything below 100-175 Hz goes to the low (18") speakers. Probably best not to set it much below 100 Hz, or you can potentially damage the 10” speakers by sending too much bass to them. Again, somewhere between 100-175 will probably work best.

A couple of potential benefits from this arrangement:

1. The cabinet will play louder now that the internal passive crossover is bypassed (passive crossovers “soak” a certain amount of amplifier power).
2. Adjusting the level of the “LOW” amplifier up or down (as well as changing the “Crossover Frequency” knob) will change the tonal characteristics of the speaker cabinet. You may possibly find a combination you think sounds better than the the way the cabinet sounds when run full-range.

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
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[Stylee Mousse]

My band in the 90s carried a mk IV as a backup head for either guitar or bass. It was never needed. I did a stack once at a bigger with the mk iV, my GK 400RB, 2 115 cabs and a weirdo 8 5” cab on top that kinda looked like a Bose 901. It actually killed that night!

Unlike the lore, the MK IV was always breaking down on us, I think we ran rehearsal vocals through it for a while.

 

[Obese Chess]

I used to have a Mark IV back in the ’80s – loved it. It’s a mono amplifier. As already mentioned, you’ll need a second (basic power) amp if you want to biamp the 1820cabinet.

With bi-amplifying, an electronic crossover is needed to separate the high frequencies from the low, sending the high and low signals to different amplifiers that will drive the speakers designated as high frequency (the 10" speakers in this case), and low frequency (the 18s). Often the electronic crossover is a stand-along unit. However, the Mark IV has this feature built-in, so an outboard device is not needed.

All you need to do is run a jumper cable between the Mark IV’s “Crossover High Out” jack to the “Power Amp Input” jack. Connect the Mark IV’s back-panel speaker output to the “Bi Amp Hi” jack on the 1820. What you’ll have then is the Mark IV powering the two 10” speakers (i.e. the highs) in the 1820 cabinet.

Back at the Mark IV, run a cable from the “Crossover Lo Out” to the input of your second amp, and connect it’s speaker output to the 1820’s “Biamp Low” jack. Bingo, you now have a bi-amplified speaker.

Next, adjust the Mark IV’s “Crossover” knob to where you want it set. This is what determines which frequencies go to the “high” speakers, vs. the “low” speakers. You probably want to set it somewhere between 100-175 (Hz). So, everything from 100-175 Hz and up goes to the high (10") speakers, and everything below 100-175 Hz goes to the low (18") speakers. Probably best not to set it much below 100 Hz, or you can potentially damage the 10” speakers by sending too much bass to them. Again, somewhere between 100-175 will probably work best.

A couple of potential benefits from this arrangement:

1. The cabinet will play louder now that the internal passive crossover is bypassed (passive crossovers “soak” a certain amount of amplifier power).
2. Adjusting the level of the “LOW” amplifier up or down (as well as changing the “Crossover Frequency” knob) will change the tonal characteristics of the speaker cabinet. You may possibly find a combination you think sounds better than the the way the cabinet sounds when run full-range.

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
Official Pedulla Club #45
Administrator, Official Heartfield Club #36
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Administrator, Official Pre-Gibson Tobias Owners Club
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Big Cabs Club #23
My Basses
My Rig: Stage and FOH Friendly
Make Your Own Cables: A How-To Guide

Wonderful, thank you! I notice that the manual makes mention of shielded vs un-shielded cables for these purposes. What's the difference, exactly? In practice, does this just mean use speaker cables to connect the amp and the cabinet, and use instrument cables to connect the crossover?

 

[WayneP]

Wonderful, thank you! I notice that the manual makes mention of shielded vs un-shielded cables for these purposes. What's the difference, exactly? In practice, does this just mean use speaker cables to connect the amp and the cabinet, and use instrument cables to connect the crossover?

Yes, so-called instrument (shielded) cables for connections between electronics, and speaker cable between amp and cabinet.

They should not be interchanged because speaker is not shielded and therefore prone to introduce hum. Instrument cables are small-gauge and can impede the amplifier from delivering full power to the speaker (speaker cable is typically at least 18 ga., while instrument cable is on the order of 24-26 ga. or so). You can search on-line for examples of each.

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
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[Hectobar]

with this commitment you need a cs-800 power amp. It will clearly fit the theme of “impossible to blow over”. Solid peavey power amp and heavy as hell.

I used one of those cabs. It crushed.

Do it!!!!!!!!

 

[J Wilson]

The basics here:

1). The 1820 is a two-way cabinet; i.e., the 2-10" speakers and the single 18" speaker are meant to receive speaker current after a crossover: The incoming speaker current is split between highs and lows (highs to the 10's, lows to the 18) EITHER internally in the cabinet through the FULL RANGE input(s) . . . or EXTERNALLY via the crossover control on the amp and the BiAmp Hi and Low speaker jacks.

2) Your Peavey head contains a single power amp section. As is, using the Full Range speaker out to the Full Range input on the cabinet, the cabinet itself will divide the signal to the 10's and 18, and you're ready to go.

3) Should you decide to use the Crossover control on the head and the BiAmp Hi and Low jacks in the cabinet, you will need a second amp in addition to your head. Could be another bass head, a stereo PA power amp, several ways to do it.


I did #3 back in the day as most bass amps crapped out at 200w, and if we needed big watts, for a while, bi-amping with big power amps was one of the few ways to keep up.

It was a big PITA, and today, with 800w amps the size and weight of a box of cigars, they're a foot note.

I'd run it like #2 and call it a day.

 

[Obese Chess]

So, I've run into a different issue - the MkIV 400/1820 combo sounded great and was violently loud at the store and at home, but in our rehearsal space is significantly quieter than the heavy rig it replaced, a MkIII Centurion (130W) and a Sunn 115. Given that I'm dealing with much more wattage and much larger speakers, I feel like this shouldn't be the case. I'm wondering if the bi-amp solution @WayneP suggested will fix it (I could stack the MkIII on top of my current rig but that's a bit much even for me), or if the amp has somehow managed to break itself in the past couple of weeks and needs repairs.

 

[WayneP]

So it isn’t as loud as the other rig. But is it getting as loud as you need, or are you maxed out?

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
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[Obese Chess]

So it isn’t as loud as the other rig. But is it getting as loud as you need, or are you maxed out?

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
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Maxed out, too quiet. I can feel it moving a ton of air, but it doesn't have any real clarity and nobody else can hear me, which doesn't make sense on a higher-wattage amp with a larger cabinet, especially one with a reputation for being ear-splittingly loud. I think part of the issue is that I'm kicking the compressor on, which is really squashing/muddying the sound, but even so the volume even maxed out is a lot quieter.

 

[Stylee Mousse]

Are the 10s working?

 

[WayneP]

Bi-amping will certainly get you more volume, but you won’t know if it’s enough until you try it.

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
Official Pedulla Club #45
Administrator, Official Heartfield Club #36
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My Basses
My Rig: Stage and FOH Friendly
Make Your Own Cables: A How-To Guide

 

[Redbrangus]

I don't know anything about the rating on the MkIII Centurion, but the MkIV amps were 400 watts at 2Ω (theoretically), so 200 watts at 4Ω. That's not a ton of power for the 3 drivers, IMO.

 

[Obese Chess]

Are the 10s working?

Feels like it.

Bi-amping will certainly get you more volume, but you won’t know if it’s enough until you try it.

Regards,
Wayne A. Pflughaupt

Make Your Own Cables: A How-To Guide Unique Arrangements of Hymns, P&W Standards, and Original Tunes
Official Pedulla Club #45
Administrator, Official Heartfield Club #36
Administrator, Official Tobias Club #133
Administrator, Official Pre-Gibson Tobias Owners Club
Administrator, Fretless Club #943
Big Cabs Club #23
My Basses
My Rig: Stage and FOH Friendly
Make Your Own Cables: A How-To Guide

Cheers, thanks.

I don't know anything about the rating on the MkIII Centurion, but the MkIV amps were 400 watts at 2Ω (theoretically), so 200 watts at 4Ω. That's not a ton of power for the 3 drivers, IMO.

130W at 4Ω on the Centurion, which hit like a truck though an Eminence 15". I guess I assumed more watts plus bigger = louder.

Sounds like this cabinet just really needs to be bi-amped, which means I'll stay running direct at shows and this will live in the rehearsal space. Ain't no way I'm getting all this in the back of a Ford Fiesta.

 

[Obese Chess]

ha ha ha. Uh, yeah, that worked alright. Thanks @WayneP .

Guitarist whose rig is on the exact opposite corner of the room from mine: "dude, I can feel you over here."

The only issue I'm running into now is really high feedback from the Centurion when the post-gain is turned up above 3, but I chalk that up to any number of issues that could stem from using two amps older than I am, and I really haven't needed to turn it up louder than that anyway.

 

[Stylee Mousse]

Are you running the high biamp out into an instrument input on the centurion? If so,too much signal there.

Prob should be going into something like “power amp in”

 

[Stylee Mousse]

Looks dope tho…