800rb rig question.

[powellmacaque]

I run a 700rb into a 410sbx+ and a 115sbx-II and it sounds pretty good. I was thinking about purchasing an 800rb and having the 700rb as a backup and studio amp. I have a few questions however:

1. I am running the original 700rb, not the rb-II. Will I lose any volume by switching to an 800rb?

2. How do the amps compare tonally? I don't want a drastic change.

3. If I am reading the bi-amping correctly (and I'm probably not), I can run the 300W section of the amp into 4ohms and the 100W section into 8ohms, and they act pretty much independently. So hypothetically, could I run the 300W part into a 210 and the 115 and the 100W section into my 410?

4. How practical is the footswitch?

5. Is there any difference in model years as far as quality?

[timmus]

here's a link to a Harmony Central thread on the 700 vs 800 vs old vs new. FWIW. It may answer a few of your questions...
http://acapella.harmony-central.com/....php?t=1253450

[will33]

Originally Posted by powellmacaque

I run a 700rb into a 410sbx+ and a 115sbx-II and it sounds pretty good. I was thinking about purchasing an 800rb and having the 700rb as a backup and studio amp. I have a few questions however:

1. I am running the original 700rb, not the rb-II. Will I lose any volume by switching to an 800rb?

2. How do the amps compare tonally? I don't want a drastic change.

3. If I am reading the bi-amping correctly (and I'm probably not), I can run the 300W section of the amp into 4ohms and the 100W section into 8ohms, and they act pretty much independently. So hypothetically, could I run the 300W part into a 210 and the 115 and the 100W section into my 410?

4. How practical is the footswitch?

5. Is there any difference in model years as far as quality?

1. No.

2. Contour on the 800rb is a chiclet button, either 0 or -10db, 700rb is a knob/adjustable. IMO, shouldn't be using that anyway. Treble knob on the 800 is set at 4k, on the 700 it's 7k. Couple little things basically but no drastic differences.

3. You are reading the biamping correctly but your description of what cabs to plug into what doesn't make much sense. Usually just set it to full range and plug one or two 8ohm cabs (or a single 4ohm) into the low outputs. I will say, with cabs made for it, the 800rb makes more sense in biamping as the lows have 2-3x the power as the mids/highs.

4. Didn't know they had one. I don't think I've ever seen anyone with a footswitch hooked up to an 800rb.

5. Not that I know of but all the ones I've had or played have been old, are still working and still sound great.

In addition, the 800's have heatsinks on the back, no fan and don't get overly hot even when worked pretty hard. That one will also be your "silent running" studio amp.

[MartinBorgen]

bi amping is only like 5kHz and above-ish something. so would be a rather stupid thing to do for a BASS guitar :P

[lowphatbass]

Yea, I've never been a fan of biamping the 800RB. This set-up with a single 15" or 18" hogging all the watts and a thirsty 4x10" on top literally starving seemed to super common 10 or 15 years ago for festival backline and what not. Realizing that it was still adequate enough for the stage I learned to leave well enough alone instead of trying to reconfigure the rig and stress out the techs.
The 800RB is extremely durable and reliable, I'd say it's in the "Top 10" as far as bass heads go in the last 25 years.

[will33]

The biamping in the 800rb ranges from stuff almost in dedicated sub territory up to high tweeter stuff and the high amp is 100watts and 8ohms. Plenty to drive a mid-driver + tweet combination down low enough in frequency to where a woofer would normally take over. Lowend power is 2x @ 8ohms or 3X@4ohms compared to the high ( read mid/high ) end. This works out the same as putting 300watts to your mains and 600-900 watts to your sub in a PA setup, a good math to start with.

The rest of the rb series, no matter how much power in the lows has a 50 watt amp hooked up to the high section and is only for tweeters. The same can be had by putting the amp on full range into a normal cab with a passive crossover and adjusting the L-pad, the result is pretty much the same, especially gigging it. That's why you get great results setting the amp on full range and plugging a cab or two into the low output (now full range output) and pretty much ignoring that little high amp thing.

I've often wondered why with the 1001 and 2001, etc. why they kept the little 50watt tweeter amp thing and never went to a more powerful 800rb or combined a pair of 800rbs together to make them the ultimate in full-on power or high-power biamp amps.

[powellmacaque]

I'm still a bit confused with the setup of the 800rb as far as connecting speakers. The amp says one section is 300W @ 4ohms and has two speaker outputs (presumably for two 8ohm cabs to make 4 ohms of impedance) and there is another for 100W @8ohms for the high end. Where does that go? Am I incorrect in thinking that you can run the bottom into one 4ohm cab or two 8 ohm cabs and the top into another, independent 8ohm cab? This is the main confusing part to me.

Could somebody give me an example of a rig that could be used with the 800rb that uses the bi-amping feature?

[MIJ-VI]

Originally Posted by powellmacaque

I'm still a bit confused with the setup of the 800rb as far as connecting speakers. The amp says one section is 300W @ 4ohms and has two speaker outputs (presumably for two 8ohm cabs to make 4 ohms of impedance) and there is another for 100W @8ohms for the high end. Where does that go? Am I incorrect in thinking that you can run the bottom into one 4ohm cab or two 8 ohm cabs and the top into another, independent 8ohm cab? This is the main confusing part to me.

Could somebody give me an example of a rig that could be used with the 800rb that uses the bi-amping feature?

IIRC the variable crossover in the 800RB allows for either:

- high pass/100 Watt 'tweeter' amp into an 8 Ω min. cab (say.., a 2 X10)

- low pass/300 Watt woofer amp into a 4 Ω min. cab (say.., a 2 X 15) or two 8 Ω min. cabs (two 1 X 15s)

or...

the 'tweeter' amp and the woofer amp can both be run in full range mode which would allow for:

- the erstwhile 'tweeter' amp driving an 8 Ω min. 1 X 15 cab

- and the woofer amp driving either: a 4 Ω min. 2 X 15 or two 8 Ω min. 1 X 15s.

--------

In contrast to the above, the crossover in the 700RB (or later) is fixed at 5 KHz and is intended only to accommodate those modern G-K cabs which support the Horn Biamp System (the Neo Series form one example) via a special speakon cable:

- >5 KHz -->the 50 Watt tweeter amp
- <5 KHz --> the woofer amp

Exact details can be found in the owners manuals for these amps.

[lbwdog]

Actually, the 800RB has a very effective bi-amp feature if done properly. The active crossover can be adjusted from 100Hz to 1000Hz, so it should be chosen to split between bass and mid-range frequencies. IMO, a good setup would be a cab containing one or two 3015LFs for bass, crossed over to a 2x8" or 2x10"(+tweeter), at around 200-400 Hz.

Or, you can disengage the crossover, and run up to three 8 Ohm cabs full-range.

[powellmacaque]

Originally Posted by lbwdog

Actually, the 800RB has a very effective bi-amp feature if done properly. The active crossover can be adjusted from 100Hz to 1000Hz, so it should be chosen to split between bass and mid-range frequencies. IMO, a good setup would be a cab containing one or two 3015LFs for bass, crossed over to a 2x8" or 2x10"(+tweeter), at around 200-400 Hz.

Or, you can disengage the crossover, and run up to three 8 Ohm cabs full-range.

Well, I already have a 410sbx+ and a 115sbx cab by GK. I was thinking about finding another used SBX cab (I really like this series of cabs) if I got the 800RB. What would you recommend, another 410 or 115, or a set of 210s? I'm leaning more towards 210s

[MIJ-VI]

A 2 X 10 would appear to match up well with your current cabs:

- the 1 X 15 + a 2 X 10 in a bi-amp rig.

- the 4 X 10 + a 2 X 10 in either a bi-amp or full-range rig.

[maxbass]

IMHO RB800 no bi-amp + 410sbx+ 115sbx = killer rig

[BLDavis]

I tried to use the bi-amp set up with my 800rb back in the '80s but it never sounded right to me. Too much missing in the middle for the style of music I play.
I still play an 800rb but I run it full range from the 300 watt side into a Neo 410.
For large rooms or outdoor gigs, I add a Neo 210 on top of the 410 and run it from the 100 watt side. I use both cabs in full range mode and it sounds great. Very full and punchy.

[DrewinHouston]

Originally Posted by powellmacaque

4. How practical is the footswitch?

The footswitch turns on and off the boost. If you use the boost all the time to get that grindy sound, then it's not very practical. I use it to get a small volume bump when I need it. For me, practical.

[powellmacaque]

Ok. Sorry if I sound like I'm not getting the point, but I was looking at pictures of the back of the 800rb... Why are there three speaker outputs (one to lo and the other to hi)?

[Bmorefoozler]

I would recommend to run the amp full range unless you Purchase(good luck) or more likely build specific cabinets made for the purpose.
That said, a band I Frequently watched in the 90's ran a 2x15 for the low and a GUITAR 2x10 for the high and it sounded righteous...

With yoru current cabs, certainly run it full range.

Does the High amp still function in full range mode? I've never seen the amp runthat way.

I believe Foz is the user that has one, with cabinets designed for Bi-amping. Look into the Fearful series of cabinets either home- made or From Don Oatman at LDS. If you only want the cab to function Bi-amped, it can save you a fair ammount of money. With your 700Rb, you would probably want a seperate full range and bi-amp inputs.

Readers digest version, get a 4 ohm SUB cabinet that functions up to it's beaming frequency or lower, and then get a SMALL cabinet that goes as high as you want, and only low enough to get to the x-over, even PA tops and guitar cabinets are designed to go lower then you would need. Typically this is the range of 6-8 inch drivers, and one should do.

[BLDavis]

Originally Posted by powellmacaque

Ok. Sorry if I sound like I'm not getting the point, but I was looking at pictures of the back of the 800rb... Why are there three speaker outputs (one to lo and the other to hi)?

The "Speaker Lo" outputs can be used with either one 8ohm or one 4ohm or two 8ohm cabinets. The "Speaker Hi" output can only be used with an 8ohm cabinet.
Now looking at the front of the amp, the Master Volume on the far right controlls the 300 watt amp to the "Speaker Lo" outputs. The one beside it controlls the 100 watt amp to the "Speaker Hi" output.
The switch to the left turns the crossover function on and off and the knob beside it sets the crossover frequency point.
If you need more info, go to GK's website and you can download the 800RB manual for free. It probably explains it better than I can.

[rpsands]

FWIW there is at least one guy using an 800rb's active crossover to run a fEarful in biamp mode

[Foz]

Ya - I do that with a fEarful 15/6+1 as a back up amp [I use a 400+ full range regularly]. The 800rb + 15/6 fearful is OK, but is not properly matched = not perfect - the 3015lf is only available currently at 8 ohms as far as I know and with an 8 ohm load your lows are 3 dB down. If you could get a 4 ohm 3015lf it'd be the cats pajamas for a portable mid forward super punchy rig IMO.

The trick to using the 800rb for biamping is you want 4 ohms for your lows, 8 ohms on the highs and then you must answer the question where on the the power curve do you want the 3:1 power split. This depends on the efficiency opf the drivers used - for the fearful 15/6I reckon its in the 700 Hz range. This is where I think most folks who don't like the 800rb biamped are doing it wrong. The high side needs to be in the upper mids - so a full range 2x10 on top makes no sense. You want something like a 6.5" mid + horn on top.

Easier to pull off than a mod'ed fEarful maybe get a blown/used & cheap three way PA cab like the Carvin LS1503 and swap out the 8 ohm 15 for a 4 ohm 15 woof that more or less matches the box volume and port - then use the exisitng mid and horn, or remove the existing them and the xover - add the Duke LeJune horn xover from the fearful wiki and select from the fearful mid and horn components - wire up the jack plate for two inputs [one to the woof and one to the xover that feeds the mid + horn]. I reckon that'd make a real nice match for an 800rb.

[Bmorefoozler]

Originally Posted by Foz

Ya - I do that with a fEarful 15/6+1 as a back up amp [I use a 400+ full range regularly]. The 800rb + 15/6 fearful is OK, but is not properly matched = not perfect - the 3015lf is only available currently at 8 ohms as far as I know and with an 8 ohm load your lows are 3 dB down. If you could get a 4 ohm 3015lf it'd be the cats pajamas for a portable mid forward super punchy rig IMO.

The trick to using the 800rb for biamping is you want 4 ohms for your lows, 8 ohms on the highs and then you must answer the question where on the the power curve do you want the 3:1 power split. This depends on the efficiency opf the drivers used - for the fearful 15/6I reckon its in the 700 Hz range. This is where I think most folks who don't like the 800rb biamped are doing it wrong. The high side needs to be in the upper mids - so a full range 2x10 on top makes no sense. You want something like a 6.5" mid + horn on top.

Easier to pull off than a mod'ed fEarful maybe get a blown/used & cheap three way PA cab like the Carvin LS1503 and swap out the 8 ohm 15 for a 4 ohm 15 woof that more or less matches the box volume and port - then use the exisitng mid and horn, or remove the existing them and the xover - add the Duke LeJune horn xover from the fearful wiki and select from the fearful mid and horn components - wire up the jack plate for two inputs [one to the woof and one to the xover that feeds the mid + horn]. I reckon that'd make a real nice match for an 800rb.

Or....

Buy a headcase, with LeJune X-over, and throw it on top of your favorite 4 ohm load. 8x10, 4x10, 1x15, 2x15, 2x12, whatever you want. Just make sure you pick a cabinet based on your preference of it's sub 700 hz content. With an 18 sound Mid Driver, the headcase should keep up with just about anything.