Sunn Coliseum Lead Conversion to Bass Amp?

alaskaleftybass · #1 11-05-2012, 05:17 PM

Hi guys, I know this is totally crazy, but I recently fell into a great deal on a Sunn Concert Lead amp. It has two channels, and a 410 cabinet.

So, here's my crazy question:

Can I convert this to a bass amp? I tried it already, and even with the old stock 10" speakers and open back it puts out great sounding bass. I know the tone controls are different than bass but I have an active Ibanez bass.

I wonder if I could put in 4 x 10 Eminence bass speakers, and replace the back panels with a closed ported plywood panel, with the port in the center. I noticed some 410 bass cabs have a round port right in the center of the cabinet.

Or I could try selling it. I live in a small town in Alaska and there aren't really any guitarists that would need something like this.

Thanks for reading my crazy idea.

alaskaleftybass · #2 11-05-2012, 05:23 PM

I think these are CTS speakers. They may be Sunn branded, but they have the cutout circle in the middle of the metal dust covers.

mc_muench · #3 11-05-2012, 05:23 PM

No need to change anything on the head, but I would sell/trade the guitar 4x10 cab and try to find a sunn 215.

nashvillebill · #4 11-05-2012, 05:28 PM

It's been a while since I looked at the Coliseum bass/lead schematics, but IIRC the only difference in the amp itself was in the preamp sections, the Lead had reverb and distortion. But--again IIRC--the basic preamp circuit was pretty much the same. FET input gain stage, in both cases, I think--going from memory though.

So the amp itself is fine for either. The cab is the difficulty. You would have to enclose the back, then use WinISD to see what drivers would match that cab's internal volume. The Eminence's might do, or they may not, WinISD can be used to predict the results.

For only a little bit more work, you could keep that cab as-is and just make a new cab from scratch, designed for exactly the drivers you want.

alaskaleftybass · #5 11-05-2012, 05:48 PM

Hmmm thanks nashvillebill, I like that idea too. I would be preserving the cab too. Thanks MC :-)

sectsmonk · #6 11-06-2012, 08:13 PM

I'm looking into buying a Coliseum Lead myself, and it looks quite a bit different... Also, yours says 'Concert Lead' on the front...Regardless of what kind of amp it actually is, it's definitely a Sunn, and I bet it sounds killer for bass.

I second the 2x15 idea, but really any bass guitar cab (which matches the head) should be a dramatic improvement over that guitar 4x10.

sectsmonk · #7 11-06-2012, 08:18 PM

Coliseum Lead pics, for comparison:

http://s304.beta.photobucket.com/use...mary%5d=images

http://s94.beta.photobucket.com/user...ad70s.jpg.html

daveman50 · #8 11-06-2012, 09:08 PM

Quote:

Originally Posted by mc_muench

No need to change anything on the head, but I would sell/trade the guitar 4x10 cab and try to find a sunn 215.

+1. The head will be great for bass. But you can't "convert" the cabinet.

alaskaleftybass · #9 11-06-2012, 10:32 PM

I stand corrected, I think I'm going senile lol.. This IS a Concert Lead. Thank you for the correction. But wow it still sounds loud and great!

nashvillebill · #10 11-07-2012, 04:52 PM

The Concert Lead and Concert Bass both share the same power amps and preamp boards, but the Concert Lead had an additional board to provide reverb...going from memory though, I sold my Concert Bass a year or so ago.

dhsierra1 · #11 11-07-2012, 05:00 PM

not tons of power, something like 150 watts at 4 ohms if my info is correct. A nice cab that's efficient would be the way to go to get the most out of it. My bias is DIY but if not possible I sure like the idea of a Sunn 2-15, esp if it has JBLs

nashvillebill · #12 11-07-2012, 05:33 PM

Yep, it has (4) 2N3055's and IIRC I measured around 150 watts into 4 ohms. I would definately not try running that amp into 2 ohms, the heatsinking is inadequate.

I had the original Sunn 2x15 with the Sunn transducers and they were anemic, maybe they would be OK with guitar but not heavy bass. I stuck JBL2226H's in that cab and thtat was a huge improvement (and driving those JBL's with much more power too).

alaskaleftybass · #13 02-01-2013, 04:27 PM

Quote:

Originally Posted by sectsmonk

Coliseum Lead pics, for comparison:

http://s304.beta.photobucket.com/use...mary%5d=images

http://s94.beta.photobucket.com/user...ad70s.jpg.html

WOWWWW Sweet stack of amps!

FYI, I used the amp stock last weekend, and wow it got loud. The difference was I was in a large room. It seemed louder in the back. I cranked up the volume to about 4 and the master up about half. The speakers didn't even distort or fart out. I play straight ahead type bass, no slapping etc. Just dumb old 4/4 notes and blues. But wow I loved it. I'm still wondering if I put in a 3" flared horn and enclosed the back, allowing the horn to concentrate the bass signal. LOL I don't think I know what I'm talking about...

Thanks to all you guys for your comments and kind suggestions...

alaskaleftybass · #14 03-18-2013, 05:18 PM

I'm going to hunt for a Sunn bass cab on eBay.... selling the cab......

heavybrother · #15 03-19-2013, 07:10 AM

I've been using a Beta Lead with a 215BH for a while, and while technically a guitar head, it sounds fantastic with bass. Not sure about active vs. passive, as I play a passive Precision, tuned to C, and it sounds huge. Probably the loudest, most gnarly 100watts I've ever heard. Definately look for a 2x15 of some sort, and you will love it.

alaskaleftybass · #16 03-19-2013, 12:50 PM

Woooo hooo, that is one bada$$ setup! Thanks for sharing!

zon6c-f · #17 03-19-2013, 12:57 PM

Try this:

A heavier cabinet, but the Sunn 1-18 vh [folded horn] @ 300 watts/ 4-ohms is magnificent; no loss of highs either as with w- horns.

Stay away from Sunn Magna 2x15's. I owned (2) of those in mid '70's.. couldn't tell difference between those and my Kustom 200 loaded with CTS.

Again.. 1-18 vh is a tone MONSTER.

zon6c-f · #18 03-19-2013, 01:07 PM

Sunn 2x15 sh 150watts/ 4 ohms... on "the bay" now.
....May be more to your liking.

If I could, I would buy it.

alaskaleftybass · #19 03-19-2013, 01:24 PM

Thanks guys! They both sound like excellent choices. I would love a Sunn cab to go with the head. Sunn is sort of Godlike to me because I remember in the day they were the biggest and baddest bass amps before everyone else started building theirs up... ummmm except for the Beast SVT 810's lol...

I live in Alaska so I'm going to have to find a buyer who's agreeable to shipping up here...

zon6c-f · #20 03-19-2013, 01:45 PM

In that case.. find a 1-18 vh and buy it; have someone clone another. Stack the 2 vertically.

Now your head will read @ 2 ohms; full power..stand back and cause earthquakes in your zone.

You'll never mention SVT again.. unless it's from your cardiologist...look that one up.