AF’s Weblog

July 25, 2012

Diagnosing and Fixing a Tube Amp

Filed under: Amps — Tags: , , , , , — audiofanzine @ 10:23 am

To read the full detailed article see:  Diagnosing and Fixing a Tube Amp

Guitar amps are, no matter how you cut it, black boxes. You may think you have control over them, but when it gets down to it, you can’t really see inside the black box, and even if you could, there aren’t any moving parts. Electricity is largely non-mechanical. Or in other words, magic. And when the magic stops, most people think all they can do is resort to prayer. Or an amp technician.

Fig. 1. My trusty Fender Vibro-King was on the fritz, and the suspects were the output tubes and the speakers.

When your amp isn’t performing up to snuff, there’s still a lot you can do without having an EE degree, or even knowing how to operate test equipment. Here are some holistic approaches—and solutions—you can try yourself, as I did when my tube amp went on the fritz. Warning: Some of the following procedures involve messing around with the components of the amp, so be careful. Electricity can kill you. Proceed at your own risk.

Creeping Death

Failure in a tube amp is often creeping and insidious, more like the wearing of the tread in your tires than a light bulb blowing. Because the changes generally occur over time, you can become inured to little degradations in performance. Then one day, maybe after you’ve been away and come back to it, you realize something’s not right. Such was the case with me and my favorite tube amp, my Fender Vibro-King (see Fig. 1). The following procedures, though, will work on many tube amps. Just swap out the specifics or make the necessary adjustment for your model accordingly.

Testing….is this thing killing?

The first test I made was just to see how loud my amp got, and if it was ear-splitting—as nature intended—at its highest volume. The Vibro-King has no master volume, so this is fairly easy to determine: wind the lone volume knob up to 10, stand the hell back, and play your guitar with the controls full out. Disappointingly, the amp, in its maxed-out state, did not rattle the windows, disturb the neighbors, and risk injury to my eardrums. I knew the amp wasn’t firing on all cylinders even without the benefit of test equipment or knowing which link in the chain was falling down on the job (if you’ll forgive the mixed metaphor). Next step: Just how is it not delivering full power?

Let’s take a closer look…

Conclusion

It’s a fine line to determine what you should monkey with and what you should leave alone when something goes wrong in a tube amp. Amps are much more difficult than guitars for two reasons: 1) They’re all electrical and not mechanical and electrical; and 2) you’re dealing with high voltage, which is dangerous to you and your amp. But that doesn’t mean that you should be afraid of your amp, just that you need to take the necessary precautions. If your amp doesn’t work and you find out it’s because of a user-replaceable blown fuse, you’re going to feel pretty foolish if you have to learn this from the tech at the shop. That’s perhaps the simplest example, but even being able to swap out tubes and diagnose problems can help you understand better your amp and even lead you to solutions—even if they’re incomplete and temporary. But that’s sometimes all you need to get you through that last gig before you can pay a visit to the shop.

To read the full detailed article see:  Diagnosing and Fixing a Tube Amp

May 21, 2012

Kemper Profiling Amplifier Review

Filed under: Amps, Guitar reviews, Hardware — Tags: , , , , , , , — audiofanzine @ 10:13 am

To read the full detailed article with sound samples see:  Kemper Profiling Amplifier Review

The world of amp modeling is merciless. It’s been a long way since the first 6U rack processors came out with their utterly obscene prices and a sound that would make every POD Mini owner laugh out loud today.

Considering the huge offer available right now it’s quite difficult to choose a product: between plug-ins (Eleven, Guitar Rig, Amplitube…), custom-shaped devices like the giant bean (Line 6 POD), multi-effect pedals (VOX Tonelab…), amplifier heads, guitar combos, rack processors, and strange things in between (VOX AmpPlug, Amplitube iRig for iPhone…), most musicians looking for different legendary amp imitations at an affordable price almost always feel helpless.

All the more since the simulation quality has dramatically increased, even if it’s surprising to see that some pioneer products are still very successful, especially the first SansAmp. Now, as if by magic, a hungry newcomer just appeared in this wild jungle. It is committed to lay down the law and beat all competitors. Let me introduce you to the magic preamp, the gear that simulates your own amps and even more, the Kemper Profiling Amplifier! With such a name you feel like in a third-rate science fiction movie, and it’s nearly true… I know, it’s hard to get excited when you hear for the umpteenth time that you can “just throw your all-tube amps away because here comes the solution to your problems: all your amps in a single, universal magic box that can do everything…”. But forget about the past: a little bird told me that this product is really valuable, that it could revolutionize modeling concepts and that it will be a crazy source of inspiration for the most creative people among us…

Winter 2012, Antarctica — A team of German scientists discovers…

Kemper Profiling Amplifier

… a small but extremely appealing unit. And this is the first highlight for people who use public transportation like me: the cardboard box containing the product is very light. It may seem like a small detail, but it does count, especially if you take into account that Kemper’s goal is to put all your old and modern amps (and more) into a single box that you can take anywhere with you to use with every single setup! In this regard, Kemper didn’t forget a thing: they also added an optional transport bag that recalls the bag of an Orange Tiny Terror, and an optional amplifier module to change the Profiling Amplifier into a real all-round amplifier head.

It’s time to open Pandora’s box and… surprise! The beast looks pretty nice (a mix of an old tube radio receiver and the control panel of a jet) even if it doesn’t feel very rock’n’roll, if you know what I mean. A good thing is the leather handle: it’s a simple feature but it gives the electronic box a classy style. The manufacturing quality is very good. Germans are famous for that and people at Kemper are no exception. Turning the controls and checking out the connections you get the impression that the unit is quite sturdy in spite of its very light weight.

So, now it’s time to power on the device and start checking out the control interface. Honestly, if you have used this kind of product before, you shouldn’t have a problem browsing the presets (yes, Kemper packed presets into the product) and edit them. The interface is not the most friendly, fun or colorful (simple display, no pictograms), but you’ll quickly find what you’re looking for: each button is assigned to the function described by its name; everything is quite practical if you think logically. Just read the short (but nice!) user’s manual and you’ll master every feature. First of all, let’s check out the presets of a product that seems to be just a competitor of the Eleven Rack (for example): to that effect I connected the master out to a Neve channel strip and sent the preamp signal directly into Pro Tools.

Now, let’s take a closer look…

Conclusion

People who know me also know that I’m a living paradox when it comes to amp simulations. My heart tells me that the endless charm and poetry of a real good amp, vintage or not, with its imperfections and intrinsic tone richness are worth the few technical disadvantages of analog gear. On the other hand, the strong scientific background I got from my family taught me to value technical progress, because only innovation can bring the human brain to new creative dimensions. And here is my personal opinion: Kemper has done an amazing job! The profiling process works really good and you can create very special sounds depending on your application and your imagination (you can can model an old radio receiver, an ambiance mic, etc.). However, I won’t sell my amps overnight — a copy will always remain a copy! That being said, huge congratulations to the team that designed this product: it blew me away! And the price is quite reasonable considering all the innovations it entails. Hats off!

Advantages: 
  • Good sound
  • Clever design
  • A real amp cloner!
  • Nice look
  • Reasonable price
Drawbacks:
  • XLR input without phantom power
  • Storing process too long
  • Really old-school way to exchange data with a computer

To read the full detailed article with sound samples see:  Kemper Profiling Amplifier Review

January 9, 2012

A Guide to Re-Amping Techniques

Filed under: Amps, Bass, Guitar reviews — Tags: , , , , , , , — audiofanzine @ 8:05 am

Re-amping is a technique that gained a lot of popularity in the last 15 years. The technique’s obvious advantages are numerous…

 

Direct recording is an ideal way to reserve tonal flexibility for mixing (especially useful in the DIY world);

Instrument amplifiers and stomp boxes offer virtually limitless opportunities to create the right sound with a not-so-virtual interface;

It’s fun, which is still allowed.

Sometimes the re-amping goal is simple. An electric guitar can be recorded direct while monitoring a software amp simulator. During mixing the direct guitar track (sans faux amp) will be re-recorded through an actual amp.

Re-Amp Signal Flow

Now let’s take a closer look…

Either or Both?

Sometimes it can be difficult to decide whether the original signal should be used in combination with the re-amped signal. In these cases there’s usually something unique about each signal, but they may not be working together well. This conflict can often be resolved by creating more contrast between the original and re-amped signals. On keyboard tracks, for example, I will frequently make significant, crossover-style EQ choices that allow me to more subtly combine the unique elements of each signal type. Another technique that can be used with remarkable ease is one I dubiously call “Sum and Amp-ness”. I think it kills for gritty bass, particularly with tight, close drums.

  1. Use a DI bass right up the middle of your mix. Get it sounding great, and setup a re-amp path;
  2. Setup a nicely overdriven bass tone on an amp. Somewhere in signal flow, HPF this path in the 300 – 500Hz neighborhood. I like to do it before the amp;
  3. Use the return from the amp just as you would use the ‘side’ component of a mid-side mic array. For maximum sum and difference affect, mic the amp off-axis.

This set-up leaves you with strong, centered low frequency focus, but adds an interesting distorted ‘width’ component. Try it out in mono-tending drum and bass situations. Finally, don’t be afraid to let the re-amp path hang out in input monitoring while you mix. There’s no real reason to record it until you’re getting close to printing mixes. It’s incredibly easy to make changes as long as it’s all still live.

To read the full detailed article see:  How to Re-Amp

November 10, 2010

Speakers, Amps & Impedance Feature Article

Filed under: Speakers — Tags: , , , , , , , — audiofanzine @ 10:39 am

Considering that speaker/amp connections, impedance, the different combinations, and incorrect wiring are a recurring source of confusion for audio heads and musicians, we decided to try to clear things up a little.

We will try to explain the most common cases and you’ll have the possibility to post your specific questions in the forums.

The two most common notions that we will use here are impedance (stated in Ohms, Ω, and which has a value from 2 to 8 or even 16 in most cases) and output power (stated in Watts, W, with a value ranging from 1 to 1,000 or even more, since some bass amps produce over 1,200 watts of power!). Following, we will briefly refer to the efficiency of a speaker, which is stated in decibels (dB) in most manufacturer spec sheets, and shouldn’t be confused with the output power stated in the same unity; don’t worry, we will explain you why.

An Ohm Story

So, we will focus on impedance and power, both for speakers and amps, and explain how to combine them for the best results and to avoid any problems. The output power delivered by an amp, regardless of whether it’s a tube or solid-state amp, is given for a certain impedance. If you fail to follow the indications given you could damage your amplifier more or less seriously, which will surely be detrimental to your wallet. Besides this tutorial, you should read the product manual of your amp first to know how to connect the system the best way.

From now on, we will use the term “amp” for “power amplifier.” In most cases a so-called “amplifier head” combines a preamplification stage (gain, EQ, compression, FX loop, one or more channels, etc.) and a power amplification stage (including the volume control and a presence parameter on some tube amps). Thus, when we speak of tube or solid-state amps, the term applies to the power stage. The fact that a preamp stage features tubes has no consequence on the behavior of a solid-state power amplification stage.

On the other hand, a combo amplifier system includes an amplifier head (preamp + power amp) plus a speaker — all within the same cabinet. But from an electronics point of view, each element has to be considered separately. The internal speaker of a combo has its own impedance and has the same electronic behavior as an external speaker cabinet. Everything that we state here applies to an amplifier head with one or two external speaker cabinets, or to a combo — an amplifier head with a speaker plus an eventual additional speaker cabinet.

We address guitar and bass players from the point of view of a musician. P.A. amplifiers work under the same theoretical basis, but they show a specific behavior. To answer your specific questions about P.A. systems, please refer to the P.A. forum.

Faithful to our “from musicians to musicians” philosophy, we will simplify everything, which will result in electronics specialists thinking our descriptions are inexact. Our goal is to explain to you how to connect your gear, and although it is always nice to understand how it works it is not necessary to know every single detail!

Let’s start with some easy theory: what is impedance?

An Ohm Story

The impedance of a speaker is the “electrical resistance” to the flow of current for a given frequency. The symbol for impedance is “Z.” The higher the impedance, the more the speaker opposes the current being delivered, and the less it develops output power for a given initial power. The resistance of an 8-ohm speaker is two times higher than that of a 4-ohm speaker. In other words, a 4-ohm speaker will let more current pass through the circuitry than an 8-ohm speaker. The lower the impedance, the more the load increases for the amp feeding it, up to the point where it could short circuit.

The impedance of an amp refers to the resistance it can handle (or it expects to experience) when a speaker is connected. In fact, the electronic circuit is conceived to work with a given impedance, which is often very low according to its construction (about tenfold less than the speaker’s), making output stages very vulnerable to excessively high loads. That’s why manufacturers state the impedance the amp can support in the user’s manual. If the resistance is too low or too high the amp could suffer damages.

Serial, parallel…

In electronics there are two ways to wire a circuit: in series and in parallel. A serial connection means that the components are wired successively in the circuit like in a string of pearls (or like stomp boxes connected one after another). A parallel connection means that the circuits is divided in several branches that feed different elements and are later on brought together again.

An Ohm Story

In the case of an amp with speaker cabinets, most connections between the amplifier head and the speaker cabinets are made in parallel. For example, the great majority of bass amplifier head manufacturers offer amps with two parallel outputs. The signal is common in the beginning, but it is divided among the two connectors, it goes through one or several speakers, and comes back (via the same cable) into the amp where it meets again with the ground/earth. The same applies to the great majority of guitar amps with two parallel outputs.

It might happen that inside the speaker cabinet some speakers have a serial wiring (i.e. they are directly connected to each other) while the others have a parallel wiring… But then again, if you already open or wire the speakers of a cabinet, you don’t need this tutorial!

Except in some rare cases (for example if you have to connect together a lot of speakers or you have weird speaker cabinets), guitar players will usually find only parallel connections, and will have to connect the amp output directly to the speaker.

 

Some speaker cabinets provide pass-through outputs that allow you to chain several speaker cabinets without coming back to the amp. Although such wiring is electrically correct, it’s better to avoid them in practice. To avoid any potential problems, don’t leave room for doubt (“which connector should I use to link my two speaker cabinets?”). Regarding such pass-through outputs on speaker cabinets, some manufacturers choose parallel wiring while the others use serial wiring. In short, it’s a headache. Use such connectors only if you know exactly what you’re doing!

Instrument cable, speaker cable…

An instrument cable is a small-diameter wire that includes a single isolated conductor surrounded by a shield. A speaker cable includes two isolated conductors and no shield. It can be an actual risk for amps (especially tube amps) if you don’t use the proper cable: to connect a speaker, you must always use a speaker cable. If you’re not sure, don’t do anything: the conductor of an instrument cable has a very small diameter, which can lead to overheating and destruction of the conductor. As a consequence, the full power cannot be transmitted anymore, which can cause damages to the amp’s output transformer.

Now let’s dig in deeper…

Conclusion

After this brief subjective digression, let’s come back to more objective things. When you choose an amp head and matching speaker cabinets or a combo plus an additional speaker, pay attention to the output power of the amp and its output impedance, as well as to the power handling and the impedance of the speakers to be sure it’s a safe system. Afterwards, it is also crucial to pay attention to connections: a wrong wiring can damage your speakers, your amp or both. So, read the specs of the product carefully and connect the right speaker to the right amp with the right cable… and make your sound rock!

To read the full detailed article see:  An Ohm Story

September 28, 2010

Mesa Boogie Transatlantic TA-15 Amp Head Review

We have recently seen the birth of some tube amp heads for electric guitars sporting a reduced size and weight, such as the Vox Night Train. This amp head format allows guitarists to enjoy their sound without breaking their back lugging gear to and fro. So now it is Mesa Boogie’s turn to launch its own portable version of a tube amp head, the Transatlantic. It’s up to us to test all of this and see if Mesa Boogie has succeeded …

Let’s Unpack

Mesa Boogie Transatlantic TA-15

First thing we notice out of the box, the very small size of the machine: 12 3/8”W x 6 3/4”D x 5 7/8”H, weighing only 12 pounds.

A “carry on” is provided with the head, just to remind us that this is a transportable amp head format. There are pockets everywhere for storing goodies found at the bottom of the box:

  • A footswitch with a button (Channel ½)
  • An HP cable long enough (about 5 meters)
  • A conventional AC power outlet

The head has a retractable iron handle iron gives it a “Lunchbox” look.  This is not the best example for ergonomics in action, but it deserves to be there (after 45 minutes in the crowded subway, my hands longed for a plastic handle). The Design and the buttons “gas cooker” style provide an unusual looking product, a bit out of time, vintage, but at the same time utilizing modern materials such lots of metals.   Finishes are well cared for and we don’t notice any defects, the “Made in USA” has its effect.

Mesa Boogie Transatlantic TA-15

The highlight of the show is when the head is turned on: a blue light emanates from the bowels of the beast to dazzle the eyes.   Question of taste, I think it looks a little Jacky-tuning, but this sensation disappears when the sound comes out of the speaker.  We would have liked the option to disable the effect of “Neon 205 GTI”…oh well!   Let’s forget this episode in bad taste (which may be felt only by me) and move on to the bowels of the head.

The Mesa Boogie Transatlantic TA-15 is equipped with 4 preamp 12AX7 type tubes, and two EL84 type tubes for power amplification.  Patented technology provides three power modes for the amp section, selectable via switches on the front. In the 5 Watts mode, the head is working on a Class A tube power, 15 Watts mode, two tubes are used in Class A mode Push-Pull, while in 25 watts mode 2 tubes operate in Class A / B power .

Now let’s get to the settings …

Conclusion

It was a pleasure to test the Mesa Transatlantic amp head, once I passed the halo of blue neon light. We like the sound it delivers, rather vintage type, bluesy or rock, as one wishes.  However, we lament the lack of extreme sounds with gain galore for playing a proper palm mute. With all the little options that the amp front panel and independent channels offer, we come to find a pleasant sound very easily.  It can also be well used both during rehearsal, as well as in concert with 25 Watts and a footswitchable channel.  In short, if it did not cost the modest sum of about $900, the average guitarist would be in heaven and it would have been easier to swallow this pill.  Apart from that, the guitarists looking for a portable head with a distinctive sound, yet with many options, will be delighted!

Advantages:

  • Successful design
  • 2 Channels
  • Tweed Sound
  • Small size
  • Convenient carry bag
  • Quality Manufacturing
  • Palette of sounds through the front panel switches
  • Adequate power for rehearsals and acceptable to neighbors
  • Footswitch included

Drawbacks:

  • Neon Blue “Jacky tuning”
  • No FX loop
  • Push / pull for the master / cut
  • A bit expensive
  • No extreme sounds

To read the full detailed article with sound samples see:  Mesa Boogie Transatlantic TA-15 Review

July 2, 2010

Marshall JMD501 Review

Every guitar player knows Marshall and its cult amp series that has been manufactured for over 40 years now. Sometimes praised, sometimes criticized – everyone has certainly heard about the Marshall Plexi, JMP and JCM800, some of which even became reference products. After the launch of a new all-tube series (JVM), a solid-state series (MGFX) and a tube/solid-state hybrid series (Valvestate), Marshall only lacked a tube/digital hybrid product range. Thanks to its cooperation with Softube (well-known for its software amp simulations), Marshall has now launched the new JMD:1 series entering the semi-digital area. Today, we’ll take a deeper look inside the JMD501…

Unpacking

The JMD501 is the 50-watt combo version of the JMD:1 product family. As soon as you take it out of the box, you’ll immediately recognize the typical Marshall look: golden front, classic knobs, logo, typography… Nothing new on this amp! The dimensions are standard for a 50-watt combo (25″ x 20.7″ x 10″) and it weights 50 lb. It features a 12″ speaker, two EL34 power tubes and one ECC83 preamp tube.

Front panel

Marshall JMD501

On the front panel, you’ll find an input for connecting your guitar and a knob for selecting one of the 16 amp models available. You’ll have to read the user’s manual in order to know which hardware is being emulated: there are no “I’m a JCM800” or “I’m a JMP-1 with a Guv’nor” labels. You’ll have to settle for ambiguous descriptions like “Clean natural” and “Lead Classic”! Perhaps Marshall didn’t want to push it too far. Just read the user’s manual to find out the topology of each model.

Marshall JMD501

The front panel also includes a standard gain control, a 3-band EQ (bass, middle, treble) and a channel volume knob. All five controls work in different ways depending on the selected preamp model.

You have four channels to which you can assign any setting. And it also features a manual mode, which is very convenient to get an overview of the amps’ sound possibilities. There is also a foot switch included that allows you to toggle between channels/presets.

Like on Line 6 amps, a single control allows you to select and adjust one of the modulation effects. You can choose between gate, chorus, phaser, flanger, and a tremolo controlled by the Mod Depth setting; the speed rate is defined by the position of the Mod Adjust knob. Unfortunately, it is impossible to mix two effects. The amp also provides a delay effect with tap tempo and different modelings that affect repetitions (Hi-fi, Analogue, Tape and Multi). Apart from that, the JMD501 includes a digital reverb. All in all, thanks to its effects and control possibilities, the amp proves to be a very comprehensive tool. The presence knob is placed at the end of the signal path, just before the master volume control. Finally, also notice that the amp is equipped with power and standby switches.

Rear panel

Marshall JMD501

The JMD501 is generous when it comes to connections! You have additional speaker outs at your disposal: one 16 ohm out, one 8 ohm out and two 16 ohm outs, plus an effect loop with send/return connectors, a +4dB/-10dB level selector and a mix control.

Marshall JMD501

The preamp output allows you to connect the JMD501 preamp to an external power amp. This connector also works when the amp is in standby mode (Silent Recording mode). The same applies to the phones output which allows you to play guitar with the sound of your amp without disturbing your whole neighborhood (in standby mode the speaker output is muted).

A line input adds the possibility to connect a line-level source (MP3 or CD player) to play along with your favorite songs. The amp also features an Emulated Line Out on XLR that emulates the miking of a 4×12″ speaker cabinet. Just like the headphones and preamp outputs, you can use it silently in standby mode.

Marshall JMD501

The Footcontroller input is dedicated to the supplied foot switch, but the amp can also be controlled via its MIDI in and out. By the way, using the foot controller is somewhat complex in the beginning. I had already tested the foot controller of the Marshall JVM210H, which is a bit unpractical (pressing a switch for the second time allows you to change mode — green, orange or red — without changing channel). The JMD501 foot controller includes six switches and allows you to store up to 28 presets directly in the Preset Store mode. You can also assign some switches of the front panel to the foot controller: manual, channel 1-4, modulation on/off, delay on/off, tap tempo, FX loop, and compare.

Now, the time has come to experience the sound of this unique amp!

Conclusion

Marshall promised to revolutionize amp technology by offering a sort of summary of their legendary amps in a single combo – and everything for just under $1,200. Reality looks very different: the price is a bit high compared to it competitors and the amp is not very versatile because the modelings are limited to Marshall amps. The cheap character of some presets disappointed me a bit (especially the clean sound), although the crunch presets sound very good and the modulation effects are quite convincing.

Advantages:

  • Crunch sound!
  • Good modulation effects
  • Comprehensive rear-panel connections
  • Supplied with a foot controller
  • 16 different simulations

Drawbacks:

  • Price
  • Clean sound a bit too cheap
  • The “war-machine” foot controller

To read the full detailed article with sound samples see: Marshall JMD501 Review

June 23, 2010

Vox AC15VR Valve Reactor Combo Amp Review

Filed under: Amps — Tags: , , , , , , , , , , — audiofanzine @ 2:31 pm

A few years ago, Vox launched their legendary AC30 as an amp head or as a combo, all made in China at an affordable price. This year, VOX is spoiling us with a hybrid series, using a special amplification technology mixing transistors and tube. This 15 Watts model is what’s on the menu for today.

Hybrid Technology

Vox AC15VREveryone has heard of Marshall’s hybrid series (Valvestate) or Fender’s. It was often a mix between a transistor amplifier and a 12AX7 tube as a preamplifier.  This technique allowed them to smooth out a little transistor stiffness and also to allow these amps to properly take on the pedals’ full power. (reminds me of my Marshall 8080 First series).

VOX uses here a different technology in the VR series: The preamp section is provided by transistors and the op-amp, while the amplifying part is based on a single 12AX7! What ?!  This can’t be right!   I admit, I myself second guessed this specification, but it is correct and verified.  It is the same technology that was used in the Valvetronix series. This “amplification” tube has even been renamed “Valve Reactor” for the occasion.

Explanation: A 12AX7 tube is a dual triode, which is present in the circuitry only to give color to the sound. It is then connected to a solid state power amplifier where the transistor amplifier is more powerful and neutral than the tube amplifier. The tube therefore serves to color the signal, the bulk of the amplification being provided by the transistors.

Autopsy

Vox AC15VR

The amp features separate channels: a clear controlled by the “normal volume” and a channel focused more crunch / distortion with two gain levels (OD1 and OD2). The “master” section includes the overall volume of the amp. It is best to adjust the volume of the channel used to get the desired sound (gain level) and then raise the master meter to increase the general level, being careful not to push too hard, otherwise saturation is inevitable (but if you want to, go ahead!). In this same section, there is also a digital reverb that quickly becomes rough when you push a little volume. But it is enough to give a little life to clean sound if you do not exceed 9 o’clock on the dial. You can manually engage it the by raising the potentiometer or by using the optional foot switch. The latter also allows you to switch between channels.

The VOX AC 15VR is equipped with a two band equalizer bass / treble, like almost all VOX amps if I remember correctly. Pushing the bass potentiometer, it overwrites the signal to unravel the inherent charm of VOX amps. Try the setting Palm Mute pushed, and you’ll understand. As for the treble, the sound tends to become a little aggressive after 12 o’clock both on its clean and distortion channels.

Vox AC15VRWe notice a control panel that runs essentially unadorned or without any funky colors.  But don’t laugh at VOX, in this model there is no amp simulation, no useless effects, no loops effects, no direct output. You just plug and play!

On the rear panel, it is possible to connect an external speaker to the amplifier and to bypass the internal speaker.  Be careful to respect the 8 Ohms impedance and perform the operation when the amplifier is off!

Conclusion

Vox AC15VRTo conclude, this little amp found for less than $400 in the USA, is sufficient for guitarists who want to play at home with the master volume that can push the gain without making enemies in the neighborhood.  It has no Speaker output, but output to an external cabinet is possible. We appreciate the ease of use, the little time it takes to find good quality sound.  In short, unless you hate the sound philosophy and VOX itself you can buy it with your eyes closed.

Advantages:

  • Good value for the money
  • Construction Quality
  • Nice crunch
  • Output to connect another Speaker

Drawbacks:

  • A little heavy for a 15 Watt
  • The overdrive type 2 too dirty
  • Channel switching not very smooth

To read the full detailed review see:  Vox AC15VR Combo Amp

May 3, 2010

Marshall JMD Amplifiers

To see more gear video demos see:  Audiofanzine Video Vault

April 28, 2010

Blackstar Amplification HT Club 40 Review

British amp and stompbox manufacturer Blackstar is known among guitar players for its Artisan Series of hand-wired amps that crunch, and its One Series, a line of hi-gain models for metal freaks. The brand is back this year with a new range of tube amps called HT Venue which ought to be less expensive but still versatile. We focus on the 40 watt combo.

Blackstar HT Club 40Blackstar was founded in 2007 when former Marshall employees decided to create their own tube amp brand. They started out by launching tube overdrive stompboxes followed soon afterwards by amps conceived in England and hand-assembled in Korea (the Artisan Series). The One Series came out one year later with a more modern sound and a much higher headroom. The only thing missing to round off its product range was a more affordable product line. This is what they have achieved with the HT Venue Series, which inherits some of the features of the more expensive series and benefits from the know-how of the Blackstar team.

This Series includes not less than six amps ranging from 20 to 100 watts including combos, amp heads and speaker cabinets. The model we review today is the HT Club 40, an all-tube, 40-watt combo sold for about $700.

Let’s start by unpacking the amp…

Dark Valvor

Blackstar HT Club 40The HT Club 40 is a juicy 53.8 lbs, 24.4″x22.3″x11.7″ baby. Under the hood you’ll find a preamp stage with two ECC83 tubes, a 40-watt RMS power amp with a pair of EL34 and a 12″ Celestion speaker. The finish is quite good with plastic knobs and on/off and standby chrome switches. The handle on top and the dark gray cabinet covering are made out of leather. The amp looks very classy but without overdoing it, which will certainly appeal to most guitar players. The amp sits in a three quarter-closed back cabinet, whose open part is protected by a grill. The HT Club 40 seems quite sturdy and it ought to withstand transportation without a problem.

The connections include a guitar input and three speaker outputs on the rear panel: one 16-ohm output for the internal or an external speaker, plus two additional speaker outputs for a pair of 16-ohm speakers (internal+external or a pair of external speakers) or a single 8-ohm speaker cabinet. Besides these connectors, you’ll also find an input for the included footswitch (nice detail!) for channel selection and reverb activation. It also features an output with speaker simulation for direct connection to a mixer or a sound card. The sound of the speaker simulation is not the best but it adds versatility and it will certainly come in handy at times. The integrated digital reverb has a selector to choose between a bright and a warm/dark effect sound. The effect won’t replace your stompbox or dedicated rack processor but it is more than enough for rehearsals.

Last but not least, a mono FX loop with a +4dBu/-10dBV switch will allow you to connect external effect units to the amp.

Let’s take a look at the preamp settings…

Conclusion

Blackstar HT Club 40With the HT Series, Blackstar offers quality amps with versatile sound possibilities at an affordable price. The manufacturing quality is good and the special features offer the user some major advantages. The different voicings provide four basic sounds, while the ISF control affects the EQ settings of the lead channel radically, allowing the guitar player to easily and quickly shape his sound. Add enough output power to play with a band plus the footswitch that comes along and you end up with a versatile and affordable all-tube amp.

Advantages:

  • Good value for money
  • Two voicings per channel
  • Effective and creative ISF control
  • Footswitch included
  • Versatility
  • Enough power to play with a band

Drawback:

  • Clean sound could have more personality

To read the full detailed article see:  Blackstar HT Club 40 Review

April 26, 2010

[Musik Messe 2010] Two Notes Torpedo VM 202

To see more gear video demos see:  Audiofanzine Video Vault

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