How to connect a vintage tube amp to a modern tube power amp

schnebeni · #1 02-14-2011, 04:41 PM

Hi everyone, this is my first time posting on talkbass so correct me if I make some kind of talkbass faux paux, but here is my question. I have two amps that I recently got through low low craig's list had to buy advertising.
1. Stereo One hundred Mesa Boogie Power Amp with 6550 GTs.
2. Vintage Sunn Solarus with attatched 2x10 combo cab.
The question is, how do I feed the output of the sunn solarus (which has no fx line, or preamp out line) into the input of the mesa boogie without some serious meltage going on? I've been warned of tube amps self destructing without proper load and I want to avoid it if at all possible. I was thinking maybe run a line out of the sunn into a DI box http://www.behringer.com/EN/Products/DI100.aspx and then running that to some crappy speaker and linking that DI to the sunn... But that just sounds like way too much. There has to be a simpler solution!
Please please please help!
Schnebeni.

schnebeni · #2 02-14-2011, 04:42 PM

*linking that DI to the mesa

BassmanPaul · #3 02-14-2011, 04:49 PM

You have only told us half the story. What do you plan to connect to the Mesa??? As with anything the details matter.

Sartori · #4 02-14-2011, 06:20 PM

Don't connect a speaker out to an input meant for an instrument or preamp.

RickenBoogie · #5 02-14-2011, 07:26 PM

It seems the 2 pieces of gear are not really meant to be connected. A combo amp, (the Sunn) is an "all-in-one" unit complete with a preamp, poweramp, and speakers, where the Mesa is strictly a poweramp. I'd use the combo as is, and buy a preamp and speakers to use the Mesa. Especially since the Sunn has no apparent OUTPUT to connect to anything.

Sartori · #6 02-14-2011, 07:42 PM

You could always buy a tube bass preamp.

Conrad Sundholm even sells one.

Passinwind · #7 02-14-2011, 07:56 PM

Quote:

Originally Posted by schnebeni

There has to be a simpler solution!

Yep. Sell the Sunn to a doom metal aficionado and use your windfall to buy a couple of nice cabs and the rack preamp of your choice.

schnebeni · #8 02-14-2011, 09:27 PM

Well the problem is I really really love the tone of the sunn. And the whole thing is going out to a trace elliot 2x10 cab.

schnebeni · #9 02-14-2011, 09:27 PM

It's just a little too quiet.

rickdog · #10 02-14-2011, 09:59 PM

Quote:

Originally Posted by schnebeni

Hi everyone, this is my first time posting on talkbass so correct me if I make some kind of talkbass faux paux, but here is my question. I have two amps that I recently got through low low craig's list had to buy advertising.
1. Stereo One hundred Mesa Boogie Power Amp with 6550 GTs.
2. Vintage Sunn Solarus with attatched 2x10 combo cab.
The question is, how do I feed the output of the sunn solarus (which has no fx line, or preamp out line) into the input of the mesa boogie without some serious meltage going on? I've been warned of tube amps self destructing without proper load and I want to avoid it if at all possible. I was thinking maybe run a line out of the sunn into a DI box http://www.behringer.com/EN/Products/DI100.aspx and then running that to some crappy speaker and linking that DI to the sunn... But that just sounds like way too much. There has to be a simpler solution!
Please please please help!
Schnebeni.

Quote:

Originally Posted by schnebeni

*linking that DI to the mesa

OK, lemme see if I've got this right... you like the tone of the Sunn, but it's not loud enough... so you want to tap into its speaker output with a DI and amplify it further with the Mesa, right?

That can probably be made to work. I've seen passive DIs (sorry, don't remember brand or model) that are meant to take a speaker-level signal. I don't know from Sunn Solarus, but if it's a tube amp you'll still need a speaker connected to it or you'll see that "serious meltage". Solid state is usually okay with no load, but check the manual, OK?

Whether that will give you the tone you want is another matter. What you're hearing from the Sunn is the product of the whole package: preamp, power amp, speakers, and enclosure, all of which have some effect on what you hear. Amplifying the signal out of the power amp may not give you the same sound as you hear out of the speaker.

You might want to think about miking the Sunn, and either putting that through the Mesa (you'll probably need a preamp) or through a decent PA.

And, as BassmanPaul pointed out, the speaker you connect to the Mesa will make its own contribution to the sound.

But hey, the passive DI is a relatively inexpensive thing to try, and is a handy thing to have around in any case. I'd say check that out first, and let us know how it sounds!

schnebeni · #11 02-14-2011, 10:11 PM

Ok, thank you! On that note, should I just use a satellite cabinet to take the speaker load off of the sunn? And is it possible that I could use some kind of resistor off of the DI to take the load? And what kind of mic can I use to mic bass? And if I wanted to replace the Sunn with a preamp, what kind of preamp would I put funds towards, because there's a huge market to choose from.

Sartori · #12 02-15-2011, 12:40 AM

If the Sunn is a tube amp, it needs a speaker load. It can't operate without one.

Passinwind · #13 02-15-2011, 01:06 AM

Quote:

Originally Posted by schnebeni

It's just a little too quiet.

It's a guitar amp and was never intended for bass duty, hence my recommendation to sell it and get something more appropriate. Also, are you sure it's not actually a 2 X 12? And it has an open back, right? One guitarist in my very first band played through one and he always struggled to keep up with the Fenders and Traynors that all my friends were using back then. But it did sound pretty nice.

Anyhow, you like it and it's what you have. If you keep using the combo speakers it only would take a few dollars in parts to build a line output into the amp, tapping right off the power amp output. Killing those speakers may not be too tough to do though. You could instead cheap out on the Behringer DI (which essentially does the same thing anyway, but likely with a little added noise), or get something nicer that can also handle speaker level signal for a few times more money. I like the DBX active DI for this application, but it needs phantom power, which is another can 'o worms. The Behringer can run on battery power, but it typically sounds better with phantom power too IME. Those DI options could keep you from needing to hire a tech to do the work for you. Or you could run the Sunn into an actual bass cab of appropriate impedance and see what that gets you. A dummy load with a line output feed is another option, or you could have a tech wire up a preamp out and not even use the Sunn's power section at all.

None of these are especially simple solutions if you're going to haul all this stuff to gigs (in which case I would just mike the Sunn and call it a day), but you still have said nothing about your playing situation or budget. The standard request in that case is to ask you to fill out your profile, so...

T-Bird · #14 02-15-2011, 01:15 AM

Hi.

The DI-way or miking the cab is the easiest solution (and will probably give the desired result), tapping into the pre-signal of the Sunn is the cleanest solution (and won't most probably be what You're sonically after).

The schematic for the Sunn is easy to find, and any tech worth his/her salt can do the Pre-out/Slave-out mod with a relative ease.

Regards
Sam

schnebeni · #15 02-15-2011, 08:20 AM

Ok, I've been doing some research and I think I answered most of my own questions. I've decided that I'm just going to scrap the Sunn, makes me want to cry :'(, and replace it with an eden navigator wp100. Is that a good option?

Passinwind · #16 02-15-2011, 08:48 AM

Quote:

Originally Posted by schnebeni

Ok, I've been doing some research and I think I answered most of my own questions. I've decided that I'm just going to scrap the Sunn, makes me want to cry :'(, and replace it with an eden navigator wp100. Is that a good option?

Take up guitar and keep the Sunn for that? Keep it at home for your practice amp?

I like the Navigator a lot. That and a Mesa tube power amp sounds like a very nice rig to me.

Oh...and welcome to Talkbass.

schnebeni · #17 02-15-2011, 11:34 AM

Haha, thank you everyone! Peace out and keep up the solid advice.

Calaverasgrande · #18 02-15-2011, 12:23 PM

REMIX
I would suggest you take the SUNN to a good tech and have a direct output added to it. I am not familiar at all with Sunn tube amp circuits but it's not too hard to do. They may be able to simply hang a resisitor off of the circuit in the right place and put a nice 1/4" jack on the back of the amp. Or if that wreaks havoc with the amp, it could be done with a 1:1 transfomer. Either way it could be accomplished for about the same cost of a DI and give you the setup you desire.
Where are you located? Perhaps someone coudl reccomend a good tech?

Sartori · #19 02-15-2011, 03:52 PM

Tube pre-amp from Conrad Sundholm: C4 Bass Preamp.

m.oreilly · #20 02-15-2011, 04:51 PM

expensive...