Features: My Diezel is a 1999 model. The VH4 has the reputation of being one of the most versatile guitar amplifiers ever made, which it easily covers just about any style you can imagine (jazz, classic rock, blues, stoner rock, metal, emo, garage rock, 80's shred, etc.) It has four completely independent preamps, which are in essence channels, that are controlled by MIDI. There are six effects loops, one for each channel and two global ones, one serial and one parallel.
All of the effects loops are tube buffered, and the input for the instrument is as well, apparently (this helps greatly if you use a long cable and are tired of signal loss). This paticular VH4 is a stereo model, the VH4S; it has true stereo capability which can sound AWESOME with effects, especially delay. This amp has everything except the kitchen sink, so there's not really much of anything that it doesn't have that I wish it did. I've used most of the effects loops so far, and they all have their perks. The reason why six effects loops exist on this amp are not because they expect you to use them all at once, rather that it provides you extreme flexability in shaping your rig (for example: imagine having an old Boss chorus with reverb in the 1st channel effects loop, a flanger in the 3rd channel effects loop, etc., and a rackmount delay processor in the master parallel loop, all controllable and programmable to bring up with the pressing of only one footswitch. Everybody's needs and wants are different.)
I use the amp for gigging and recording, and it definetly provides. The power that this amp has is staggering. I have Ruby EL34STR's in it now, and its conservativly rated at about 120 watts with those. The VH4 and VH4S will take any power tube that you can imagine with the flick of a switch: KT88's, EL34's, 6L6's, 6550's, KT66's, etc. It is EXTREMELY sensitive to power and preamp tube changes, which makes it even better if you're after that sound in your head. // 10
Sound: Ok, there are many misconceptions about the sound of this amp, most of which come from people who have only played on one for a few minutes, heard someone else play it, or haven't even ever heard or played one at all. It will not slaughter your Dual Rectifier, kill your friend's JCM 800, or whatever. Diezel amps, especially this one, have their own tone; they don't sound like anything else out there right now, although some comparisons can be made. The point of this amp is to cover as many sounds as possible and sound really, really, really good at each one.
The Diezel VH4(S) tone is very "Hi-Fi", meaning that its extremely balanced across the whole spectrum. There isn't nearly as much "give" as most amps, and its very unforgiving if you're a sloppy player. If you make a mistake, everyone will know it. However, if you can master playing it, the tones that it will reward you with are some of the most satisfying that I've ever experienced. The attack is very fast and immediate, and the amp is very tiGHT. I know I sound like a tool saying this, but the closest thing that I can relate it to is a finetuned Ferrari: the experience seeing a Ferrari Zoom by is ok to pretty cool, but driving one at full tilt is another world altogether.
As far as being a heavy sounding amp, the VH4(S) does not approach the Bogner Uberschall or the Diezel Herbert. While it does sound very modern, its more Marshall-ish in its overdrive channels. It can get pretty heavy and it punches you in the chest on every channel, but it doesn't have that razorblade sound that you can get from a Uberschall. Nevertheless, I still play it over any other amp being made today.
I use two Gibson Les Paul Customs, a 1969 Black Beauty and a 1978 Silverburst w/ Tom Anderson pickups with a coil tap switch in the neck pickup tone knob. I have several other ones, but these two offer a huge range of tones by themselves. I play a lot of stoner-type rock and heavier stuff, like in the vein of Kyuss, Mastedon, Crowbar, The Melvins, Prong, etc. My true love is 70's prog rock, especially King Crimson. This amp handles pretty much anything I throw at it. It is extremely quiet, its scary. When I first got it I turned it on, switched to channel 3, EQ'd it up and cranked the masters to 10 o'clock. No hiss or anything. I hit a chord and it scared the living crap out of me. This amp is loud. very loud. I'll go through each channel:
Each channel as a seperate knob for: Gain, Volume, Treble, Midrange, and Bass. Channels 1 and 2 have seperate bright switches.
Channel 1 (Clean):
This channel has a huge amount of headroom. Its pretty difficult to make it distort, but if you crank the gain all of the way you can get a very nice, stinging overdrive. Crank the channel's volume knob with that setting and it gets very velvety. The clean has been described as sounding like a cross between a 60's Fender Twin and a Hiwatt, which seems to pretty much cover it. It punches you in the chest very hard when loud, and the bright switch makes a huge difference if you want to get that caustic 60's garage rock tone or a twangy country vibe. Overall, this channel is best described as the best piano sound ever made for guitar if definetly makes single coils sound almost like a Grand.
Channel 2 (Clean/Light Overdrive):
I don't usually set this channel up for clean, but when I do it has a very tight bark, reminciant of an old non-master volume amp just waiting to be unleashed. When cranked its AC/DC, all the way. I'll often put my Fender Blender in front of this channel to get that fuzzed-out late 80's early 90's grunge sound, ala Billy Corgan (who, incedently, is using two Diezel VH4's now). With the bright switch off and the neck pickup on with the tone rolled down, it does a great Duane Allman tone. You can hear every note, nuance and finger slide, so its best to be careful.
Channel 3 (Heavy Overdrive/Rhythm Channel):
If you've heard of Diezel amps, its because of this channel. Woo boy, does this channel smoke! It sounds HUGE and FAT, and its impossible to muddy up. No matter how much gain you have piled up on it, you still can hear every note in any chord that you play, clear as a bell. The distortion doesn't cover up your sloppiness, either. I can do so much with just this one channel. It even does a good clean when I roll the volume knob down. Its so responsive, balanced and harmonically rich its disgusting. IMO, this is the absolute finest modern overdrive channel ever made. It paticuarly excels at modern riff-based hard rock. My best friend said it sounded like the best modded JCM 800 that he's ever heard. I love JCM 800's, this thing's just different to me. When you play one, you can be the judge.
Channel 4 (Lead):
What?1? EVEN MORE gain!?! You'd better believe it! This channel picks up where channel 3 left off. It isn't as lound and ribcage-shaking as channel 3; its more compressed and balanced. It was designed for lead playing, which it definetly excels at if you're a shred-head. Lower gain settings do sound great, but lets face it: there's no point in raising the gain knob past 10, 11 o'clock! This channel has a natural midrange hump in its voicing, which is there to help you naturally cut through the mix. When set with the channel volume high and EQ'd properly, it can be a very heavy sounding channel (but not Uberschall heavy. Look at the Diezel Herbert for that). // 10
Reliability & Durability: This amp is built like a tank in Northern Bavaria in Germany. If one of the power tubes fail, there's a built in fuse and indicator light that tells you which one failed. Plus, it knocks out the matching tube to let you finish the set without having to stop! Pretty cool, VERY cool. Since I bought it used I had it serviced by Uwe Salwender in Los Angeles, the Diezel distributor for the United States. I haven't had a problem since. Both Peter and Uwe are extremely good people, who are willing to bend over backwards to make sure that you are getting the sound that you're hearing in your head. They have the best customer support I've ever had, tied with Zvex Effects. // 10
Overall Impression: This amp is it for me. I love it so much, and with the EL34's in it it has that grind that a Marshall lover like me wants, plus a totally different tone than anything else out there. Pretty much anything that I want is right there at my fingertips. I've been playing for seven years and I own a lot of other gear (check out my Zvex reviews). If it were stolen I couldn't afford another. If you get the chance to play one, try it and give it more than 20 minutes. I'm pretty sure that you'll like it. // 10