Correct Cab for my vintage Earth Head

[lapubell]

So, this here is my first post on TB. I've trolled around a few threads here and there, and love all the quality responses people give here. Here's my question.

I have an old Earth Sound Research B2000 tube head that sounds dirty awesome. I really don't know much about large wattage electronics as I'm more of a small electronics nerd (<12 V, pedals, circuit bending, etc). I got the thing tuned up from a local dude here in Portland, OR and it sounds amazing. It's got that vintage warmth, and enough EQ options to make me smile, but I think the cab situation is lacking.

It has two outputs, and I was told from the local amp dude that I should be aiming for 4ohms each output. My current cab is this rad old Sunn 2x15 that is currently running at 8ohms. It's got 2 4ohm speakers in it, and they are wired in series (i think) which gives it the 8ohms.

So, should I split the speakers apart and wire each one to it's own input jack, so they each run at 4ohms? Is there a pair of speakers that I can add to it to bring the total ohms down to 4? Is that a stupid idea?

Thanks in advance for the responses. I can give pics upon request.

[JimmyM]

you're fine as is. that head runs at 8 and 4 ohms. just looked it up...

http://earth.ampage.org/node/2615

[fu22ba55]

I don't think pics would help, but I'd sure like to see pics of an all tube Earth Research head. All the Earth stuff I've seen pop up has been solid state.

Pics of the Sunn 215 would help too... theres the 215S, and the 215B... pretty much the same animal, except you can' fit some larger drivers in the 215B because of the internal structure of the cab.

You need to figure out how many watts the amp is rated at. (I'd wager around 100-300 depending upon how old it is.

You also need to figure out EXACTLY what kind of speakers are in that Sunn cab, so you don't blow them up.

Theoretically, if they are 4 ohm drivers, and the head will run at 2 ohms (two parallel 4 ohm loads), then yes, you would theoretically get a bit more volume by running each speaker individually.

---

Lots of maybes. We need pics of everything!

[v-grooves]

If it is not too much trouble, I would love to see a couple pics of that awesome head. When I was playing as a young punk in the early 70s, the closest I came to an Earth head was a friend who played in my band and I was able to convince him to leave the rig at my house for a few nights as it was so damn big to move around.

Droppin some low notes through the 2-15 cab, I proceeded to shake the plaster dust off of the ceilings for a while until my dad lined up a backhand to my head. It never made contact, but I got the idea.....stop.

I wonder where they got the name of the company from.....it would be cool if someone had that trivial answer.

Any rate, I am just looking back to my early years of playing the Fender bass and the Earth name always sparked my interest.

Let us know how things go redesigning your rig & best of luck.

Vince

[fu22ba55]

Now my interest is piqued...

Found these images on THE GOOGLE:









I know Earth was famous (infamous) in the late 70's for knocking off Peavey designs... if I had to wager, based upon the name only and those 4 6550s... I'd postulate this was a Sunn 2000S clone? Is that possible?

[Lowbrow]

Earth was abundant during my formative days - cheaper than most gear, and to my memory very good sounding.

[walterw]

i found a schematic for it here.

it appears the output is arranged like an old fender: the second speaker jack is not a separate tap from the transformer, but just parallel with the first jack. (it's just that the "main" jack has a shorting switch to keep the tranny from operating into an open circuit, which is why it is supposed to be plugged into first.)

if the amp is a fender clone (as some cursory googling suggests), then it likely is meant to run at 4Ω. if it is built like the fender, then it will tolerate the mis-match of 8Ω or 2Ω, but will run best, and develop the most power, at 4Ω.

[puremusic]

I am getting g.a.s. for one of those, I used to play through my dads when I was a kid. I wished he still had it I may start looking around the neck for one.

[Lowbrow]

See also:http://www.plush-amps.com/new_photos_home_page.htm

[D.M.N.]

The Earth B-2000s is a fender rip off, exact same as a Plush Royal-1060, or whatever they called it. Most of the Earth stuff WAS Peavy rip offs, but the early Earths were just Plush's based on fenders (Plush became Earth)

[v-grooves]

Did you get a free pair of male platform shoes with the purchase of a Plush amp? Damn they dumped a lotta sparkle into that vinyl paint.

I wish I would have saved a few of those old musical eqpt catalogs from the 70s (back when Community made some real speakers). The catalogs had all the gear I ever wanted in there, but couldnt afford (they had G.A.S. back then?).

Those catalogs sat at the top of the stack, even on top of my old Penthouse mags.....I just read the text in the catalogs, they had some good stories in those catalogs....honest. Ha!

Vince

[lapubell]

Yeah that's the amp. When I bought it it had no case at all, just the metal casing and guts. No tubes either.

I've put some money into it and it sounds super nice. I built my own casing for it and wrapped it in the yellow vinyl and it looks pretty awesome IMO. I'll post some picks tonight.

How would I go about finding the output of the amp? The google says that it's 100W, and 8ohms, but i'm guessing that means two 4 ohm cabs. That's what the repair man said anyway.

I'll bust out the screw driver again and open up that cab. It's got ~30 screws holding the back on, and it was quite the chore to open it up last time. Oh well.

[lapubell]

Ok, so as promised here are the pictures of the amp and cab.









notice the little tiny jack. That's all that's on the back, no info or nothing.





That says 4ohms, 60 watts. They are wired in series, so that should make this an 8ohm cab, with 120 watts rms power handling, right?

[fu22ba55]

Well, the yellow vinyl certainly doesn't disappoint.

Originally Posted by lapubell

That says 4ohms, 60 watts. They are wired in series, so that should make this an 8ohm cab, with 120 watts rms power handling, right?

That sounds right to me...

Someone should be along shortly to identify that Sunn Cab for you... it doesn't look like an 2000S cab (center port), so I'd take a wild guess and say 200S or Spectrum II?

There are others among us who know this cab.

[lapubell]

yeah I can't find anything about this cab online.

I hate to use this setup as it is right now. I know that they aren't working correctly together at the moment. I'm getting that nasty over loaded speaker sound whenever I turn it up past 3. It sounds great at low volume, but I need a cab that will work with my head at high volumes for mid/bigger gigs.

I'm hesitant to start rewiring things until I hear back from people on TB.

Thoughts?

[edbass]

Originally Posted by lapubell

yeah I can't find anything about this cab online.

I hate to use this setup as it is right now. I know that they aren't working correctly together at the moment. I'm getting that nasty over loaded speaker sound whenever I turn it up past 3. It sounds great at low volume, but I need a cab that will work with my head at high volumes for mid/bigger gigs.

I'm hesitant to start rewiring things until I hear back from people on TB.

Thoughts?

It's old; pre 1969, but it could be a couple of things.
What are the measurements of the cab? If it's 11.5" deep, I suspect it's a 1967 Sentura II or Spectrum II cab, if it's 15" I suspect it's a '67 Sonic II, a '68 Sentura II or Spectrum II cab.
Of course it could be anything if someone has replaced/modified the baffle, and honestly I can't identify what baffle that is, so that may be the case.
I'm also pretty sure those are replacement drivers, I believe the cab itself pre dates those drivers by a few years.

What it isn't is a 2000S, 200S, a Sorado or other Sunn bass cab. I think it's one of my above choices, and it probably had JBL D130's in it originally.

This is a 200S next to it's big brother the 2000S. It shares the same center port and ducting (as well as the D140F's) as the 2000S, just scaled down.



You should post your pic on the Sunn Forum, one of those Sunn-O-Philes will probably nail it promptly.

It's hard to gauge from the photo's, but it seems shallow to me. I'm going with 1967 Sunn Sentura II.

[Plstrns]

Holy crap that's a shallow 215!

[lapubell]

yeah, it's really shallow. only about a foot deep, maybe slightly deeper.

so, should i try and run this thing at 4 ohms by pulling each speaker out to it's own jack, and see how that goes, or leave it as is and sell it off for something that works with my head?

opinions?

[KramerBassFan]

you might have the speakers out of phase - just a thought.

[dmusic148]

Or one or both of them are blown.