GK 400 RB

[JAS]

I just bought an old GK 400 RB head on Ebay. I was wondering what kind of speaker cab people have had success pairing this with.

Also, how much volume can I expect to get out of this head? How would you describe the sound?

How many watts should I look for in a speaker cab to compliment this amp?

Should I go with a 15" or 12"? I seem to like 15" speakers for their warmth and punch for both electric and upright.

[mrpc]

Try an old Altec 421-A 15". Nice combo with that amp.

[bassbob]

The 400RB's are light and powerful for their size. I got one a while back and it works really nice with an old Yamaha 15" cabinet. I am finishing up a 2 8" speaker cabinet and hope to try this out soon also. I did have a 200 RB way backwhen that was nice but a little weak in louder bands.
Good luck.

[JAS]

O.K., I know this has been discussed a lot but here goes...

The GK 400 RB is 200 watts at 4 ohms.

-I am looking to buy one 4ohm 15'' speaker cab

-Should I get a speaker cab that has a power rating of...
a) 200 watts
b) more than 200 watts (how much more) or
c) less than 200 watts (how much less)


I understand that the debate is you can achieve a better sound with the amp having about twice the wattage of your speaker cab but you run the risk of blowing your speakers. What is headroom?

[mrpc]

What kind/brand of single 15" 4ohm cabs are available out there?

I wonder what the difference in sound will be using one speaker and changing the impedence to 4ohms, instead of the more common single 8ohm load?

I suggested the old Altec speaker only because I recently spent some quality gig time with an older 400Rb/ 8 0hm 15"Altec (in a small Carlson reflex cab) combo, and it really sounded good, for electric bass anyway. Very dynamic. Not super loud, but I didn't need to be loud, as there was P.A. backup.

I'd say that you ought to just try some different cabs and see what sounds and feels good, maybe try an outboard preamp for the acoustic bass, for extra EQ.

[JAS]

The manual says to use one 4ohm speaker or 2 8ohm speakers. Why would you use one 8 ohm speaker? You would only be getting half the power out of it right?

[mje]

Originally Posted by JAS

The manual says to use one 4ohm speaker or 2 8ohm speakers. Why would you use one 8 ohm speaker? You would only be getting half the power out of it right?

But that might be all you need. I mean, my Traveller 400 can work into 4 or 8 ohms. I used an 8 ohm cab for BG because I like the sound, and it's plenty loud enough.

[JAS]

I guess that might be all you need, but why not have the ability to maximize your equipments potential. Most amplifier manuals say to use either one 4ohm speaker or two 8 ohm speakers. 2 8ohm speakers are equal to the same power as one 4 ohm speaker. One 8 ohm speaker would only have the capacity for half the sound output that the amp is capable of providing. I am guessing that the sound quality would be much better if you are getting the most efficient use of your power as well.

[mje]

Originally Posted by JAS

I guess that might be all you need, but why not have the ability to maximize your equipments potential.

That's sort of like arguing that you should get the biggest engine available for your car to maximize its potential. You may not need it. I could get the maximum volume from my amp with a pair of 15" horn enclosures. But I get all I need from one 12" box.

Originally Posted by JAS

... I am guessing that the sound quality would be much better if you are getting the most efficient use of your power as well.

Untrue, for two reasons. One, the impedance of the load has nothing to do with the efficency of the amplifier. Two, load impedance, as long as it within spec, has no effect on the sound quality (linearity, whatever) of a properly designed solid state amplifier.

Impedance is only critical with tube amps, where using the wrong load can make the output tubes operate outside of the linear portion of their transconductance curve.

[mrpc]

I'm not sure, but I'm guessing that the GK will give you about 150 watts at 8 ohms. Your amp tech can measure it on the bench for you.

And the amp probably won't work as well or sound as good at 4 ohms into a SINGLE speaker. Again, I'm guessing.....

Why not just go out and find some different speakers, and see how they sound, before purchasing anything. Sometimes even an older P.A. 15" or monitor cab can surprise you, especially if it's CHEAP!

The 400RB is a great amp, and the good news is that you can get 'em at a very nice price used!

[fdeck]

Carvin makes a 4-Ohm 15" cab, but it's a beast, and likely to be too boomy for upright, just guessing from its sheer size. My thought is that you should take note of what is nice about the 400RB head, and buy a speaker with the same attributes: Compact and portable with killer tone. An 8-Ohm 1x12 will probably get you more than enough sound for upright bass. If you ever need more sound, a second cab gets you the add'l power, plus an extra 3 dB sensitivity.

I've had good luck using a 400RB paired with a Bag End S15. I used this setup at a few gigs but found that I wanted a smaller amp. That said, the electric bass sound was awesome and the upright bass sounded almost as good. I've played GK amps through SWR and Hartke speakers on gigs but my Bag End 15 has been my favorite so far.

Edit: I agree that double bass tends to sound better through twelve inch speakers compared to fifteens.

[fdeck]

I think that so long as the 15 is not too bassy, it can sound great with DB. This is the same, AFAIK, as adjectives such as Punchy, Tight, Quick, and Responsive. I got there with a DIY 15" cab that is, if anything, too tight. Just a couple days ago, someone one the EB side mentioned the S15 as being tight sounding.

[fdeck]

I just noticed that Schroeder makes a 4-Ohm 1x12.

The Bag End S15 is the tightest, punchiest 15 that I've ever used.

[mrpc]

Bag End is great! The old Altec 421-A in a "tight" cab and with 100-200 watts fits that description as well! Sweet sound.

[FredH]

I like the sound of the GK 410 powered by the GK 400 RB. I have always liked 10” speakers. It must be a holdover from my EB days but I like the quickness and fuller middle tones you get. Heck 12” speakers are nice too but I can't use anything bigger.
There’s a lot to be said for matching amps and speakers from the same manufactures. Good chance that the engineers used company gear when they did the initial design work.

Course gear match up is a dark art.

[winston]

I have an '87 400RB (original owner). It sounded very good through an EV-loaded BagEnd S15D I had but the best combo I've found is with a Euphonic Audio Wizzy 1x12. It's a small, light (29#), efficient 4 ohm cab that pairs up well with the 400RB. This setup gets louder than I've ever needed for DB and sounds very good with BG, too. I usually find myself cutting the highs and high mids a bit.

One nice thing about the 400RB is that if you don't like the sound of the GK preamp you can use any stompbox EQ/preamp (I've used a Boss Bass EQ pedal, Fishman Platinum Bass EQ/DI and various SansAmps) into the FX return--the boost control has enough gain to let you use an instrument-level signal to drive the amp to full volume.

[mrpc]

Originally Posted by winston

but the best combo I've found is with a Euphonic Audio Wizzy 1x12. It's a small, light (29#), efficient 4 ohm cab that pairs up well with the 400RB. This setup gets louder than I've ever needed for DB and sounds very good with BG, too. I usually find myself cutting the highs and high mids a bit.

That's valuable info here. "Small, light and efficient, while pairing with the amp well" are the cab specs that JAS seems to be looking for.