SWR Grand Prix Preamp

Some of this amp's more interesting conveniences include:
- Ladder LED display in upper left-hand corner. Helps set optimal pre-gain level and looks great!
- Aural enhancer circuitry. Does the most commonly performed EQ tweaks all at once. Seems like it boosts low mids to increase cut, scoops hi mids to create transparency, and maybe ups the bass and presence just a taste. A very subtle control that defines the sound and brings the bass forward in the band's mix just a bit.
- Killer built-in tube direct box. You get adjustable pad, ground lift, and line/direct. In line mode, of course, you're sending the preamp line out to the board, but in direct, which usually means just the raw bass signal will go to the board, the Grand Prix will send the raw bass signal AFTER it gets warmed up by the tube! Beats the heck out of any solid-state direct box, even with tube emulation. I mean, would you rather have tube emulation or real tube sound? Oh, I almost forgot the XLR-out mute. Pull the knob out to keep your tune-up out of the board (but don't forget to push it back in after tuning).
- Killer built-in headphone amp (use with stereo headphones only). OK, here's the deal--you plug your practice tape or CD into the effects return, get the mix just right with the effects knob, and wail away.
- Hi-pass filter. You pull out the bass knob to start cutting out frequencies from 30 Hz down. This insures you are keeping harmful low frequencies from eating up your headroom and destroying your speakers.
- Tuner jack (yeah!)
- Sidechain effects loop. I don't have to sell you on this. But if you have problems hearing yourself in the studio mix, if the XLR-out is in "direct" mode, you can plug the headphone mix into the effects receive and use the effects blend to balance how much you hear of yourself to how much you hear of the band.
- There's other great stuff, but the main point is, if you buy this preamp, it's like having a super-flexible tube direct box and a headphone amp thrown in free.

Tube preamp. This is the strong and weak point, the tube sound. My '98 Bass 350 came with the best of the Russian tubes, which sounds brash and flabby all at once. This old green-line Grand Prix came with a Chinese tube (I wonder if it's the fabled Ruby Tubes 7025) that sounds fantastic.

What it boils down to is that SWR has built a great preamp, but it's up to you to put a great tube in it, because your entire sound goes through and depends on this one tube. If you buy a tube preamp and you want the best it has to offer, be prepared to invest some time and money (it's gotten so far out of hand for me that I ended up buying a mutual conductance tube tester, which entailed learning about tube testers, and now I'm waiting for new tubes for it). However, it's not as big a time drain as reeds are for reed instrument players, and once you get some good ones, you're through looking.

So far I have found two great P-bass tubes. For roundwounds, I like the lively and tight Tungsram ECC83. For flatwounds, I have a 1959 Sylvania black plate, gold print JHS 5751 that really takes the harshness out of the highs (particularly noticeable with stainless flatwounds) and unmasks the sound to let the low P-growl come through. One more thing, all the good tubes are out of production, so be prepared to do some hunting and learning, and especially, listening using your own particular combination of bass, string, and speaker.

EQ: Has 4 EQ bands with adjustable center frequencies. This is really important and very welcome moving from the Bass 350. The bass needs two mid bands, the lower to increase lower mids to improve cut as needed (to get through the band's mix), and the upper to cut upper mids to add transparency (makes sound more pleasant by removing nasal frequencies).

General construction: This amp is a high-performance amp that was built to give the best possible sound. Part of the price is a turn-on transient. Personally, I'll take that one thump per gig (which you can easily work around) in order to get great sound all night.

Would definitely use it on a gig without a backup. Have been using SWR preamps (built into various amps) for years without backup and never, ever needed one. However, regardless of the stone reliability of SWR products, if you get stupid or careless, you're on your own.

I e-mailed SWR once about an amp I was planning on buying used (asking what was the year of the amp in the photo I sent, and what features were added in what year), and they replied a few days later, very thorough and courteous. Aside from that, I've made no contact. SWRs don't break on me. And I don't need to ask too many questions. They've got the best user manuals in the business, all online along with a suggested settings GIF.

Overall, this is a very musical preamp. It is not my favorite sounding preamp in the world. The Fender Bassman normal channel is, and just for fun, I am going to build one of those soon, three knobs, two jacks, one tube. However the Grand Prix is the best real-world bass preamp for me because I don't work in a vacuum and I have to think about how I'm going to interface in the most musical way possible with the board. Maybe there are better preamps out there, but I got this cheaply at eBay in great condition and it does everything I want and more with tremendous convenience and reliability. It's good enough that for now, I'm through messing with preamps (except the fun project) and plan to spend my time messing with tubes, strings, and speakers instead.