 |
| Hi Jeff, I have a Bellari ADB3B direct box which has a tube. I hooked it up to the mixer at church and the soundman said it produced a distorted sound in the lower notes on my five-string bass. I don’t hear the distortion in headphones or through an amp. Could the tube be blown? How can you tell when the fuse is blown? Jerome |
Hi Jerome,
To answer your questions, if either a fuse or a tube was blown the unit would likely not function. However, the tube could still be contributing to the problem. The tube used in your unit is a standard 12AX7/7025 tube, but there are many different 12AX7 tubes currently available and some seem to reproduce low-end better than others in different applications. My suggestion would be to audition as many tubes as possible to see if you can find one that minimizes the distortion.
The unit can be configured a couple of different ways and you may be using it incorrectly for this application. According to the manual the unit has two gain settings, -20db and +20db. The -20db is recommended for a line or speaker level signal, while the +20db is recommended for guitar level. In reviewing the specs, the -20db setting has a frequency response of 20hz to 40khz, which is fine for guitar or bass. The +20db setting, however, has a stated response of 50hz to 20khz – not so good for bass guitar, where the low E string has a frequency of 41hz and worse for your bass, since the low B string has a frequency of 31hz. Sending a signal through the unit that is out of the useable frequency range can cause the signal to become distorted. My suggestion would be to try running the extension speaker output of your amp into the unit using the -20db gain setting and see if that cures the problem.
Here’s to clean living – I mean signals.
| My ’65 Fender Twin reissue is about ten years old. The reverb on it is very weak, even when fully cranked. I gave the amp a good kick with the reverb at 10 and heard a huge “sprong!” that even woke my kid up, but when I plug in it is very subtle. It used to sound like a canyon of reverb – is there a problem with the tube? Also, my vibrato is on the skids. It’s as if it has no depth, just a slight shimmer. At some faster settings it doesn’t even sound on. I had the lamp replaced three years ago, but that didn’t seem to help. Thank You, Chris |
Hi Chris,From the sound of your explanation we can assume that the reverb recovery circuit is working fine. This leaves the reverb drive components as the cause of the malfunction. I would start by replacing the reverb drive tube. This is a 12AT7 tube and should be the third tube from the right when viewing the amp from the rear. If you have an extra 12AX7 tube handy, you may use that for troubleshooting purposes. If you don’t have a spare 12AX7, you may borrow the 12AX7 from the first position on the right – the normal channel preamp tube.
If the tube is not the cause of the problem, I would next suspect the reverb tank or cables. Unplug the reverb send and return cables from the underside of the chassis. Then, using a multimeter, measure the resistance at each plug from the center pin to the outer shell. One plug should read approximately 1-2 ohms, with the other reading approximately 175-200 ohms. If you are missing the latter, the problem is either a faulty RCA cable or an open transducer on the input of the reverb tank. By removing the reverb tank and measuring directly at its input jack, you will be able to determine if the problem lies in the tank itself or the connecting cables. If this all checks fine, the cause is either a bad reverb drive transformer or other internal components, and is something a good amp tech will need to verify.
As far as the vibrato being weak, you mentioned having the lamp replaced. Most of the time when servicing a vibrato problem, a tech will replace the entire vibrato assembly. If you literally meant just the lamp in the assembly, there is little chance that the problem would be repaired since a weak photoresistor in the assembly is usually the cause of the problem, not the lamp itself. You could try replacing the fifth tube from the right – the tremolo oscillator tube – with a known-good 12AX7 and see if that cures the problem, but other than that the amp will need to go to a good tech for further troubleshooting.
Jeff Bober
Co-Founder and Senior Design Engineer – Budda Amplification
jeffb@budda.com
www.budda.com
©2007 Jeff Bober
EBS BassIQ Blue Label Triple Envelope Filter Pedal
The EBS BassIQ produces sounds ranging from classic auto-wah effects to spaced-out "Funkadelic" and synth-bass sounds. It is for everyone looking for a fun, fat-sounding, and responsive envelope filter that reacts to how you play in a musical way.
Reverend Vernon Reid Totem Series Electric Guitar - Shaman
Silos features six presets, tap tempo, one full second of delay time, and three voices—two of which are styled after bucket-brigade and tape-delay sounds. In the $150 price category, it’s not unusual for a digital delay to leave some number of those functions out. And spending the same money on a true-analog alternative usually means warm, enveloping sounds but limited functionality and delay time. Silos, improbably perhaps, offers a very elegant solution to this can’t-have-it-all dilemma in a U.S.-made effect.
A More Complete Cobbling Together
Silos’ utility is bolstered by a very unintimidating control set, which is streamlined and approachable. Three of those controls are dedicated to the same mix, time, and repeats controls you see on any delay. But saving a preset to one of the six spots on the rotary preset dial is as easy as holding the green/red illuminated button just below the mix and preset knobs. And you certainly won’t get lost in the weeds if you move to the 3-position toggle, which switches between a clear “digital” voice, darker “analog” voice, and a “tape” voice which is darker still.
“The three voices offer discernibly different response to gain devices.”
One might suspect that a tone control for the repeats offers similar functionality as the voice toggle switch. But while it’s true that the most obvious audible differences between digital, BBD, and tape delays are apparent in the relative fidelity and darkness of their echoes, the Silos’ three voices behave differently in ways that are more complex than lighter or duskier tonality. For instance, the digital voice will never exhibit runaway oscillation, even at maximum mix and repeat settings. Instead, repeats fade out after about six seconds (at the fastest time settings) or create sleepy layers of slow-decaying repeats that enhance detail in complex, sprawling, loop-like melodic phrases. The analog voice and tape voice, on the other hand, will happily feed back to psychotic extremes. Both also offer satisfying sensitivity to real-time, on-the-fly adjustments. For example, I was tickled with how I could generate Apocalypse Now helicopter-chop effects and fade them in and out of prominence as if they were approaching or receding in proximity—an effect made easier still if you assign an expression pedal to the mix control. This kind of interactivity is what makes analog machines like the Echoplex, Space Echo, and Memory Man transcend mere delay status, and the sensitivity and just-right resistance make the process of manipulating repeats endlessly engaging.
Doesn't Flinch at Filth
EarthQuaker makes a point of highlighting the Silos’ affinity for dirty and distorted sounds. I did not notice that it behaved light-years better than other delays in this regard. But the three voices most definitely offer discernibly different responses to gain devices. The super-clear first repeat in the digital mode lends clarity and melodic focus, even to hectic, unpredictable, fractured fuzzes. The analog voice, which EQD says is inspired by the tone makeup of a 1980s-vintage, Japan-made KMD bucket brigade echo, handles fuzz forgivingly inasmuch as its repeats fade warmly and evenly, but the strong midrange also keeps many overtones present as the echoes fade. The tape voice, which uses aMaestro Echoplex as its sonic inspiration, is distinctly dirtier and creates more nebulous undercurrents in the repeats. If you want to retain clarity in more melodic settings, it will create a warm glow around repeats at conservative levels. Push it, and it will summon thick, sometimes droning haze that makes a great backdrop for slower, simpler, and hooky psychedelic riffs.
In clean applications, this decay and tone profile lend the tape setting a spooky, foggy aura that suggests the cold vastness of outer space. The analog voice often displays an authentic BBD clickiness in clean repeats that’s sweet for underscoring rhythmic patterns, while the digital voice’s pronounced regularity adds a clockwork quality that supports more up-tempo, driving, electronic rhythms.
The Verdict
Silos’ combination of features seems like a very obvious and appealing one. But bringing it all together at just less than 150 bucks represents a smart, adept threading of the cost/feature needle.
EarthQuaker Devices Silos Multi-generational Time Reflection Delay Pedal
