sunn 200s tube studio preamp for bass?

[thecraig]

hi everybody,


im a new guy here though i have admittedly been a lurker for the last couple months. i am a pro studio bass player in nashville, tn. i have finally seen the light. not long ago i had never played thru a real tube sunn amp. in fact i had no idea they ever built a tube amp. i only knew of their solid state 80's stuff which was never my thing. so now fast forward a few months and i already own 2 sorado heads, and 2 2-15" cabs, and my coliseum pa head gets here this weekend hahaha. before my divine revelation, i was using a drip edge dual showman in the studio, but now am totally devoted to the sunn. i am just blown away by not only the warmth and tone of these amps, but the total instrument definition at the same time. just amazing. so i use my sorado at every session. sometimes i get to use a cabinet with it, but most days i am direct. in those instances i use a dummy load with a direct output into a neve 1073 and a urei 1176 with various pedals on the front end. in a track you would be hard pressed to pick out the direct sound from the mic'ed up jbls. its really that good. so my question is this..... i have a tech that is going to build a studio preamp for me, possibly using one of the sorados for parts. i am wondering what are the essential components to keep in the circuit? im not much of an electronics guy so i really am in the dark. what i know is that i really love the way the rig sounds as is, but would love to lighten my load a little and cut down on setup time. how much tone is coming from the output transformer / tubes? since i dont need to power a cabinet at 90% of my sessions, how much of the heavy bits (if any) can be left out without compromising the tone of the circuit as i am hearing it now? also would love input from cats such as edbass who clearly have thought all this stuff thru, from the other side of the soldering iron, what pitfalls to look out for, points that need to be brought up with the tech, and generally any features that would come in handy that i might not have thought of. this is a fantastic forum, and i have already learned so much. i really appreciate the shared passion for these amazing amps, and the ability to learn more about them. thanks and greetings from nashville to all.

craig

[Oli]

Hi,

I talked to TAD a couple of years ago abot the Sunn's and thier (big) output transformres. I think that  these transfiormers do have a  effect on the sound. I do remember when fender did put these little trannis in their guitar combos and the sound was totally differnet. What I do know is that the KT 88 / 6550 do have a HUGE effect on the sound and the dynamic. The bg hit with the "small" tube heads is that you can easyly go into the tube satisfaction. This gives you "compression". With the Sorado I do use nearly no compresion on the bass in the mix (though I do not have the UREI or Fairchild compressor for myself, maybe that yould change my mind... ).

What kind of dummyload do you use? Is it just a plain resistor or something with a inductive load like these:

http://www.tubeampdoctor.com/product_info.php?products_id=385

I'm curently getting myself in reamping, using a Dummyloyd (just resistor) with these:

http://www.tubeampdoctor.com/product_info.php?products_id=666 and an RE 20 with the box. Not too happy with this setup at very moment...

Greetings

Oli










 

[biltmore]

In my opinion, the tubes and transformers have just as much to do with the sound as the pre-amp. I've seen transformer tests before, where they use the same exact model of amp with the same specs & tubes ... and there really is a difference.

[Isaac]

Craig, your tech should be able to wire up a temporary preamp out from the Sorado. With that, you can try it and see if that will give you the sound you're looking for. If it does, then a lighter preamp can be built. If not, well, then you have your answer.

[thecraig]

Great feedback everybody. U guys confirmed my suspicion. There Are no extra parts in my amp haha. Go figure. God bless u Conrad! Shifting gears on the pre. Thinkin now about just leaving the Sunns alone and making a hybrid showman/ 200s. Really want to get a killer speaker simulation / dummy load thing going on it. Oli, to answer ur question... I'm using a thd hotplate set to load utilizing the direct out.  It sounds pretty damn good but I would love to get something that sags like a speaker when u hit it hard. Is this the same oli from the musicman stingray forum? If so ur sound sAmples are epic man and have really helped me a bunch!

Craig

also... Anyone have info on the Conrad c4 tube bass pre? Is it essentially a 2000s w the contour knob? No info on his site. Admit that I haven't searched this forum yet. 

[Soundmasterg]

Great feedback everybody. U guys confirmed my suspicion. There Are no extra parts in my amp haha. Go figure. God bless u Conrad! Shifting gears on the pre. Thinkin now about just leaving the Sunns alone and making a hybrid showman/ 200s. Really want to get a killer speaker simulation / dummy load thing going on it. Oli, to answer ur question... I'm using a thd hotplate set to load utilizing the direct out.  It sounds pretty damn good but I would love to get something that sags like a speaker when u hit it hard. Is this the same oli from the musicman stingray forum? If so ur sound sAmples are epic man and have really helped me a bunch!

Craig

also... Anyone have info on the Conrad c4 tube bass pre? Is it essentially a 2000s w the contour knob? No info on his site. Admit that I haven't searched this forum yet. 

I'd suggest that you email Conrad and ask him about it. He's very friendly.

Greg

[CLD]

I contacted Conrad in October 2008 about this preamp and it looks like a good unit. I'm sure the tone is there. If the economy hadn't turned south, I would have one  by now!

At the time he was selling them direct for $695. Here are the specs he sent me:

C-4 Bass Tube Pre-amp
The C-4 is a fresh design incorporating the latest technology and unique tone circuitry.  The rack-mount pre-amp is clean, quiet and wallops a punch.  There is great versatility in the tones you can achieve.  In the studio, the C-4 develops an active and alive low end.  It doesn’t sound pinched off according to a leading producer-engineer.  Reports received say the C-4 is unbelievably punchy.  The contour control is one of the favorite features of the C-4.  Recording engineers report that those problematic upper bass frequencies are very easy to dial out.  We are also receiving feedback that the highs are very extended and are rich in harmonic content.
Front Panel Features:
- 1 Instrument Input Jack
- 1 Tuner Input Jack
•  1 Instrument/Tuner Select Switch
•  1 Input Volume control
•  3 Tone Controls – Bass, Contour and Treble
•  1 Master Volume Control
•  Jewel Pilot Lamp
•  Power Switch

Rear Panel Features:
   •   Power Cord
   •   Fuse Post
   •   ¼” Unbalanced Output

Construction Features:
* 2-Space Rack Mountable Steel Black Painted Chassis
* 1/8” FR-4 Hand Wired Terminal Board
* Conrad’s custom Super Wire (Details)
* Chassis Mounted Ceramic Tube Sockets
* Galactic Star Grounding Scheme for reduced hum and noise
* Stainless Steel Hardware

Tube Complement:
* 1 JJ/Telsa 12AX7 Preamp Stage
* 1 JJ/Telsa 12AX7 Gain and Output Buffer Stage

[Oli]

Oli, to answer ur question... I'm using a thd hotplate set to load utilizing the direct out.  It sounds pretty damn good but I would love to get something that sags like a speaker when u hit it hard. Is this the same oli from the musicman stingray forum? If so ur sound sAmples are epic man and have really helped me a bunch!

Hi,

no, sorry, have never been to the mm forum, I'm more up for te P-basses...(well I should think of getting one singray with this old, fat bride).
I know the Hotplate, I used it in a studio session a couple of years ago (mid 1990s), I think with an borrowed SVT amp. The sound on the tape was really good, easy going. Though I thought the small fan was quite noisy.

Have a lok at this toy: http://www.tedweber.com/atten.htm . It uses a "speakermotor" which is in fact just the coil of the speaker. Great idea, though I've not bought it (yet). Maybe someone around has already tested it.

Greetings

Oli

[noel]

I've thought about building a stand-alone version of the 200s preamp.  I haven't done it yet because I've been busy with other projects.  All you'd have to do is replicate what you see on the schematic minus all the gain and output stages.  Basically from the instrument input to output of the treble control.  The 6AN8 is a pentode triode in a single package which acts as 2 gain stages before going to the output section.  The only question really is do you clone the power supply exactly or come up with a better way of getting the rail voltage for the 12AX7 since that's all you're really powering.  I'd suggest just coming up with a new power supply as you only need to supply the 320V so the rest of the original power supply is overkill for this type of project.

I think a preamp like this would sound really good but as I say I haven't tried it yet.  I don't know that you can say it will sound the "same" as the whole rig for a lot of reasons.  Audio myths die hard so this is the way I think of it: the preamp is where you shape your tone but the power tubes, OT etc. certainly effect the character of the tone.  Bottom line, you're not really comparing apples to apples when you use only a preamp versus an entire bass rig (even if the preamp in the rig is the same).  That said, I think you'll be pleased with how just a Sunn preamp sounds. 

It should be a really easy project since its just a 12AX7 and a couple discretes plus a 320V power supply.  I hope this helps the project and let us know how it sounds when you get it built up!