subdirectory_arrow_left subdirectory_arrow_left Solid-State Guitar Preamps
Gear Solid-State Guitar Preamps {{currentManName}}swap_horiz Select a
Find a manufacturerkeyboard_arrow_down
  • settings_backup_restore
140 products20 news items1 reviews35 classified ads60 user reviews2 discussions

Review Solid-State Guitar Preamp

Tonebone PZ-PRE: The Test

Tonebone PZ-PRE Acoustic Preamp When Radial engineering, who has a reputation for making quality gear, branches out into acoustic instrument pre-amps, the result is the Tonebone PZ PRE, a pedal with two high-impedance inputs, a boost and an EQ. Let's take a look... read more…

User reviews on Solid-State Guitar Preamp products

Smoking hot versitale distortion (Amt Electronics - DT-2 Dist Station)

By MountAnDewMe, 15/01/2013
The Distortion station from AMT electronics is perhaps my favorite and most versitle transistor based distortions around. The unit can be powerd fron a nine volt battery or from an AC adapter.The unit has one quarter inch input and one quarter inch output. There are rotary knobs for controlling level, low, high, and gain. There are also three independent three way switches that select amp type, modification, and mic simulated placements. American, British, and Tweed are the three amp types available. The modifications available include Clean, High gain, and Hot wired. The three mic placements are Classic, Center, and Off-axis. These switches combined with the highly interactive tone controls create a tone tweakers dream come true. The pedal is fully analog so you are working with real sounds and not struggling to make fake sounds behave as real ones like with some digital models.


As with my other early AMT purchase there was no documentation provided in the box however the AMT site does contain great detail about their product line. A manual would have been nice with this pedal though because of all the variations available. As far as tone creation is conserned there are almost too many ways to shape the output. Take time and learn how each of the switches interact with each other and then how the basic four knobs vary those options. Rest easy though because in general it is easy to create totally awesome sounds. The pedal ranges for subtle to outrageous and everywhere in between. Do not let the lack of a mid control imply this pedal can not do metal. By using the switches properly and boosting the low and mid you can get an insane amount of metal distortion suitable for the heaviest or fastest riffage needed.


I have had a pleasent experience using this pedal with my entire guitar collection ranging from Gilmour to Yngwie to some of my death machines. While I do own a vast collection of pedals this one covers the most ground by far. It can be fairly warm considering it is transistor based and scream with out being overly harsh, unless harsh is what you are shooting for. My favorite use for this pedal though is for Metal, all types and varieties. To me it is my go to distortion box for placing in front of an amps clean channel. No matter what you are going for though be assured that the pedal is clear and capable of loads of saturation without some unpleasant results I have heardin other pedals. Also unlike most Metal based pedals this can do hard rock to acid rock to blues to sqweak and sqwuak regae tones.


There is nothing about this pedal I do not like and the only thing I could find to improve on it would be a fourth switch to engage a tube, but I have tube based units and more things could ruin what I consider to be one of the most valuable pedals in my collection. Definitaly a desert island unit if you get my drift. This pedal may seem a touch higher in price than comparable units but its versitility more than justifies its cost. I ordered this pedal site unseen after hearing many sound clips, yes I know they can be deceiving at times but this time the chance paid off. At the time of purchace AMT units were very hard to obtain and I am forever thankful that I did not stop the pursuit of this pedal. I am always previewing pedals but this purchace raised the bar on what I accept as a good unit. I would definitaly do what I had to do to replace it if it were gone but it is well built and hopefully it will always be there for me.

100% Diezel (Diezel - Zerrer)

By madchap, 30/07/2015
This is a FET preamp fitted with 2 individual channels (Gain, Treble, Middle, Bass, Volume). It also offers a presence and a deep control, and a master volume, All 3 knobs are shared by the two channels.
The preamps comes with no manual and a somewhat cheapish power adapter. One may think that someone is trying to cut down costs and boost profit at Diezel... if we didn't know better!:-D
The aluminium body is thick, sturdy and quite bulky, and yet the preamp is rather light (1.3kg). The Zerrer offers no less that 6 kinds of outputs so most situations should be covered! We have a "amp in", a "poweramp in" that can also be used as a "stereo FX loop" (send/return), a "compensated output" (w/ cab sim) for mixing desks, a headphones out (ofc w/ cab sim), an external footswitch control in case we want to trigger the Zerrer from a distance, and finally an "auxiliary in" with two independent volume knobs to plug in our MP3 player or other sources!

The Zerrer is a true bypass preamp, but when activated sound only goes through when connected to the "amp in" output...which is obviously when we need it! Otherwise the bypass footswitch is used to mute the preamp.
I'll be honest I think the preamp LOOKS pretty bland and common...knobs are not of the Diezel type and the overall design could easily be improved but, hey, aesthetic is only second to tone! And in that department the Zerrer delivers big time!

If you're already familiar with Diezel amps, clean/crunch channel is from D-Moll and lead channel is VH4 (channel 3)
If you're not, let's say that gain-wise channel 1 goes from a Fenderish or JC clean type tone to a big crunchy JTM or JCM800+. You can dirty the clean channel VERY progressively. Channel 2 more or less picks it up from there and brings us into high gain territories. Think VH4, Herbert or 3x Rectifier (the amount of gain, not the tone!).

Tone-wise, the Zerrer brings us Diezel signature sound. It's extremely sensitive to attack and picking styles (just like a real good quality TUBE amp, no less!), and of course the guitar you'll plug into it will greatly influence the tone. Honestly it's so impressive to hear how responsive it is that I need to mention it once more! I've had many preamps and amps over the course of the last decades, and this one ranks at the very top for sure!
Depending on how high you set the channel volume, EQs will be relatively or extremely sensitive. Basically if channel volume is full on, the tiniest turn of a knob has a huge impact on the tone. When channel volume is set at noon, it is more what you'd expect from a standard amp or preamp.

It is only my opinion but I believe the Zerrer needs to be plugged into a sort of poweramp. I use a torpedo and the combination of the two is terrific! I also tried to plug the Zerrer into Recabinet 4 and it sounded pretty good, though not quite as good as into the torpedo. The Headphones out in comparison sounds like plugged into an IR file. When I first used it I found the tone somehow lackluster. Mind you, it's quite decent and pretty usable and useful when on the road for sure, (and better than any mass-market modeler out there!) but still, we're a far cry from what a "fully fledged" (so to speak) Zerrer can deliver!

My previous preamp was a Mesa boogie V-Twin (good tone, but definitely not as versatile as the Zerrer) The Zerrer is definitely as responsive as the V-twin, even more actually IMHO. I have also owned a Herbert for several years (the first models) . To very briefly compare the two, the Herbert is way more versatile than the Zerrer, and is also voiced slightly differently, so the Zerrer can only mimic a fraction of what the Herbert can do, but it's not all that bad, as with a bit of extra EQing, I can get close enough anyway ...and it's way more convenient to carry around than a 30kg head and a 4x12!! But Peter, if you read me, we also need a Herbert preamp! :-D

All in all, I'm very pleased and satisfied with the Zerrer. It is a frigging great piece of gear that delivers an awesome tone, plus, it's portable and very versatile. Once more Diezel puts out an excellent product on the market and above all one that should disappoint none! It's small in size but delivers big time! If you're looking for a high quality and portable preamp at an affordable price, just grab one, you just can't be disappointed!

you can hear it on my souncloud page (mostly metal stuff though):

Alter Your Guitar Tone in Seconds or Change a Strat into a Humbucking Axe (Walrus Audio - DEFCON4)

By MGR/Brian Johnston, 03/10/2018

DEFCON4 is not your typical EQ pedal. First, it’s a preamp that offers up some compression and push in tone, and so you get some energy behind those crafted changes. Second, the choices behind each EQ setting (Bass, Midrange and Treble) are very well honed, so that each selection (adding or taking away bass, mids or treble) is obvious, thus making it easy to dial in a better (different) sound than what your pickups are producing. Third, the 10dB MOSFET boost is just the right amount to thicken up your tone and make it more three-dimensional. The YouTube video with this review goes through the various settings with a humbucker-equipped guitar and through all the various bass, midrange and treble settings. You can hear how the DEFCON4 can enhance both clean and higher-gain settings. However, what is even more impressive is how you can take a single-coil Strat and make it sound like you’re playing with higher output humbuckers.

To repeat, each EQ has settings that were very well-crafted, although you can get under the Chassis and change each bandwidth if so desired. The Bass adds bass without sound muddy, or takes it away without sounding too thin. The same is true of the Midrange and Treble, in that you can tweak a bit here and there and nothing is out of whack, and yet is obvious to the ear. DEFCON4 likely is one of the best tools to reshape your tone so that you can get rid of that weak jangly sound, clear up muddy pickups, etc. And when on stage you can switch from humbuckers to single-coils and not miss a beat, all at the push of a footswitch.

DEFCON4 is the signature pedal of composer and performer Ryan Adams, DEFCON4’s original intent was to allow Mr. Adams the ability to switch from a humbucker guitar to a Strat, and still be able to produce an equal amount of output and fullness in tone. Along with Walrus Audio, DEFCON4’s claim to fame has become a super fast tone-shaper, possible with only a few clicks of a 3-band equalizer and along with a 10dB MOSFET boost, if necessary. Some of the pedal is bells and whistles, such as the name, the little Defcon 1 through 4 lights, and certainly a world map that lights up with missile launching schematics – but who cares? It looks friggin’ cool and it is fun to use. If looking cool isn’t an issue, then I suggest all guitar manufacturers stop with the fancy paint jobs, graphics, and body designs. Not likely, right? And for those old enough to remember, the overall artwork and pedal design concept comes from the 1983 movie WarGames and Ryan Adams’ “love for all things 80’s nostalgia.”

The tone-shaping capabilities of this pedal are exceptional, and the gang at Walrus Audio pulled this one off very well. Each click of each EQ bandwidth seems to change a guitar’s tone noticeably and in a very usable manner. Perhaps you don’t want full-out treble, but even when cranked to the limits it still sounds good, particularly with darker pickups. The point is that you can achieve a multitude of different tones very easily so that the same guitar can become a very different guitar.

Do note that there can be no change in tone if you keep all the EQ settings pointing to 12-noon (zero). From there you have four choices on each… two steps down (-1 or -2) or two steps up (+1 or +2). For example, if you consider the Bass knob you can decrease bass a bit by clicking one step counter-clockwise, or remove even more bass with two steps counter-clockwise. Conversely, if you want more bass than click one step past 12-noon for more bass, and even more bass with one more click. The same works for the Midrange and Treble knobs. This makes operation of DEFCON4 easy since the degree of change from one position to the next is noticeable, but not extreme, so that you can add or take away just a little or a moderate amount (but not so much in either direction that the tone doesn’t sound usable). This is not like many other EQs that seem to offer an almost infinite amount of fine-tuning, which actually makes it challenging to zero-in on that ideal tone. As a result, DEFCON4 makes it very easy to remember past settings, or at least easy to achieve them again in a matter of seconds. The 10dB MOSFET boost can be used on its own or in conjunction with the EQ (and vice versa) and has a number of potential uses in different situations. For example, you could use the EQ to shape your tone and then add the 10dB for lead solos, regardless of the guitar. Or you could use the 10dB with EQ to thicken up your single-coil guitar. In regard to the latter, there are some musicians that likely enjoy jamming on a Strat for some hard rock or even metal, but those single-coils just don’t have the output and thickness of tone desired. That can be rectified with one pedal… DEFCON4.

DEFCON4 measures about 3.5 x 4.5 inches (8.9 x 11.4 cm), with a solidly built aluminum chassis. The feel of the pots when turning the knobs are of good quality as they ‘click’ from one position to the next. The plastic knobs are of good quality, while the small switches (to engage or disengage each EQ knob) are both solid in feel and located in a protective location… just beneath and between the larger EQ knobs. The input/output for cables are located along the sides, as well as the power supply (standard 9v 2.1 mm @ 100mA) insert is on the side. This places the inserts in a more precarious position (as compared to rear chassis inserts), but being a slightly larger pedal it’s unlikely one’s foot would step on any cables while stomping. Likely the only ‘fragile’ part of DEFCON4 would be the LED screen showing the graphics, although you do not need the screen to operate the pedal (it’s simply a ‘cool’ factor). Regardless, I cannot fathom actual damage from normal and regular use, as opposed to abuse and dropping something on it. For more information you can check out the pedal at:

News Solid-State Guitar Preamp

Feeling Luke-y?

Published on 10/21/15
ToneConcepts, Ernie Ball and Sterling by Music Man are holding a contest to win Steve Lukather-related gear and goodies.

Forums Solid-State Guitar Preamp

Solid-State Guitar Preamp classified ads

Radial Tonebone PZ-Pre

$175 Reverb classified ad

Boss Guitar Driver GL-100

$99 Reverb classified ad