Monday, November 14, 2005

Adventures in Tube Emulation

I recently bought a Sansamp Programmable BDDI (Let's call this the SAPBDDI for short … hmm, not very short, is it … maybe I’ll just say Sansamp) and this has recently distracted me from more meaningful engagements (like updating my blog or other cyber-loafing). Here is what I’ve learned so far (Warning: these are totally biased, and not necessarily informed opinions; your milage may vary):

  1. I’m running this with a Thunderfunk 550, Accugroove Tri112 and dbx160A compressor. I've (per the Sansamp manual) put the dbx160A in the pre-EQ loop, and the Sansamp in the post-EQ loop. Well, maybe not; what the heck, I still can't decide where to put this. Maybe I'll just run it into the input.
  2. SansAmp's preprogrammed 'fat tube' sound is very addictive ... I've put my Ritter Roya on passive humbucker mode, and really love the tubey sound. It doesn't quite get that overdrive 'squeak' that you can hear with real tubes, but otherwise, it's pretty nice. The Thunderfunk is warm, but the Sansamp adds a little something extra which I'm still trying to figure out. Anyway, for this alone it is worth its modest price.
  3. The SansAmp manual says it is low noise, but I'm spoiled by the Thunderfunk, which is even lower noise. So in comparison, the Sansamp adds some noise ... not much, but noticable. That said, the footswitches (which the manual says are custom) are completely noiseless, and have a nice feel when hand operated. You can always take the Sansamp out of the loop with a step on the footswitch, and its noise drops to zero.
  4. Here's how to control Sansamp noise. First, never boost the line out level (at least not in this configuration). Boosting will only add noise. Second, do put the Sansamp after the preamp-EQ section, and keep the preamp gain low. Third, if you are going for a vintage sound (I’m using my Variax 700 Bass on vintage Jazz / flatwound setting) then turn the treble EQ down on the Sansamp. This will cut way down on the annoying high frequency digital noise which is from the Sansamp, not the TFB (definitely). If you need the higher frequencies (for slap as they say) then turn the level and presence down, or conversely, just live with it if you want that distorted tube sound. You need to fiddle with the settings for each different bass you input, but there always seems (IMHO) to be a setting where the sound is ‘tube modulated’ the way I would like, yet where the Sansamp noise is acceptable.
  5. The Variax Bass sounds are very much improved by the Sansamp!
  6. The 'lazy pot' feature of the footswitches is brilliant. You step on a switch to change settings, and the old setting turns off instantly, but the new setting fades up over a few seconds. The gives you time to drop the volume on your bass pot if the new setting it too loud.
  7. It's definitely worth it to have 3 switchable sounds. And the 3 footswitch package is actually a more practical shape for the Sansamp. Well worth the price differential over the non-programmable.
  8. I've not used a real tube amp, so don't know what I'm comparing to. But if this is close to the sound, I can see why musicians are willing to put up with the expense and weight of tube amps. My guess is that the Sansamp provides better tone that a tube preamp like, e.g., the Demeter, or GrooveTube, because it is a mic-ed speaker emulation that captures the tube-speaker interactions.

I seem to have made a big improvement in the noiseiness of the Sansamp by upgrading the cables on the Post-EQ loop. I have my own caples put together from Sommer-'The Spirit' cable (a very good German instrument cable) tipped with Neutrik NP2x 1/4" plugs. This cleans up the Sansamp sound almost completely, though I really don't know why -- whether the Sansamp is picking up noise, or if its the Post EQ of the TFB550

The Sansamp manual notes that you can have unusual interactions with two digital devices in the signal chain, because of Sansamps A/D - D/A conversion (because their tube emulation is through analog circuitry). I've noticed this when I put my Variax Bass at the front ... turning the bass' knobs can elicit squeeks and buzzes if you are not careful.

Is it as good as a tube amp? Hmmmm ... not yet. I've got a GrooveTubes Brick on order, and I'll make a definitive decision when I A/B them in a couple of weeks.

Tubes rule. I think they still do; I'm not sure ...big, hot, heavy, expensive, fragile ... but in the back of your mind, you still wonder if you aren't missing something with solid state.

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