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April 22, 2019
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Amp Insider with Brandon Montgomery: The Dumble Zone PDF Print E-mail
Tuesday, 02 June 2009 10:16
Part 1

GJD: There seems to be a lot of misnomers about Dumble amplifiers in terms of the models names, voicings, serial #s, etc.

BM:  I agree but I don’t think any one really knows all the exact details except the man himself.

GJD: In your opinion, why is there such a mystery and lack of clarity around a lot of the details about these amps.

BM: Well, I think there is a few factors that come into play.  First off, there is a lot of misinformation based on hearsay and just like anything else, inaccurate statements that get repeated over and over end up being what people believe. 

Second of all, there are less than 300 Dumble amplifiers in existence.  They are scattered throughout the globe and no two amps are exactly the same.  Also, there are variations upon variations which again can lead to inaccurate descriptions.
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Amp Insider: Amp Logic PDF Print E-mail
Wednesday, 06 May 2009 08:41
by John Tomaszewicz, President, JT Sound Inc.
With so much discussion and emphasis on guitar amp components, I thought I would add some perspective having been a professional Components Engineer for much of my Engineering career. I have often thought that universities should have a course on Components Engineering to focus on component specification and selection. An important part of my job function was to find out what components would fail in the field or in production, and then find a solution. Quite often, I found that even the most gifted engineers would fall prey to relying on a component to perform to an unspecified parameter. The most common problem was not a bad component but things such as the component manufacturer improving their process and consequently enhancing their yield. This resulted in the device no longer functioning in the product the way the designer intended.

INTERCONNECT RELIABILITY PROBLEMS: Mechanical switches are often the weakest link due to contact wear and increasing contact resistance. Gold contacts must be mated with gold contacts or they provide an inferior junction to a less costly tin plated to tin plated junction.  Simply stated, similar metals provide a better junction than dissimilar metals. Common use of jacks as a switching mechanism in effects loops has shown to be problematic.  Primarily because of oxidation on the contact coupled with a reduction of contact force due to metal fatigue.

CAPACITORS: Ever see a capacitor specification for frequency response?   Probably not.  Most engineers know that electrolytic capacitors exhibit objectionable distortion and frequency roll-off.  Even capacitors that are often thought of as good quality can have serious deviation from an ideal capacitor frequency response within the audio band. Is this roll-off acceptable and desired?  This would be an example of relying on an unspecified parameter.

ECONOMIC SHIFTS: Common guitar amp tubes almost became extinct during the late 80’s. Amplifier manufacturers had to shift to less favorable tubes to maintain production.  We need to keep an eye on supply through these extremely tough economic times.  A good contingency plan would be wise. Don’t get caught producing a product that relies on some unspecified magic.  e.g.  What if your unique transformer manufacturer goes away? Shocking as this may seem, I have been through this type of issue many times and often the only solution is a costly and painful lifetime buy.  As simple as these issues may seem, the exorbitant cost of ignoring them can be overwhelming.
 
The Skinny on 9v Pedal Power Supplies PDF Print E-mail
Monday, 30 March 2009 14:50
By Benjamin Fargen - GJD Contibutor
So you have you’re brand new snazzy pedal board all laid out and assembled with your favorite new and vintage pedals…but you think to yourself….”this is the third brick of 9Volt batteries I have gone through in 2 months?...not cool…I need a better way to power this battery buster!”

This time we will explore 3 different ways to get the precious power needed to a pedal board… whether it is an off the shelf solution or custom built DIY style, I’ve got you covered.

Single “Wall wart” style pedal power source:


There are several companies including “One Spot” and “Godlike” that make high current capacity single outlet transformers (some up to 1700ma) that can power multiple pedals (15-20!) via a daisy chain wire system. These units are affordable and work well for most players using standard 9V pedals. For custom boutique pedal users…please check with the company before using this type of power supply…I have had conversations with many pedal builders that frown upon these units because they are an unregulated power source. Certain pedal units can be damaged that do not have a self regulating power supply input…that being said… I have used this type of power supply with many different pedals and never personally had any problems or issues.
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The Pedal Insider: Junction Capacitance and The Miller Effect In The Fuzz Face - Part III PDF Print E-mail
Thursday, 19 March 2009 11:26
Part III : Deathnium
By Theo Hartman - GJD Contributor
As the industry continued to explore ways to improve the transistor it became clear that using vacuum deposition techniques to deposit ultra-thin layers of material onto wafers provided far superior control over junction geometry and carrier longevity. Likewise, material purity improved. As a result, the end of the 1960’s saw a mass migration to planar technology whereby semiconductors were constructed via epitaxial (deposition) techniques instead of alloying.

At the same time, there was a race to establish Germanium or Silicon as the semiconducting substrate of choice. Silicon won for a number of reasons but basically because the teams working on it finished first. Germanium is actually faster (for electrons to cross the junction) than Silicon, but this took second-fiddle to market readiness and no doubt other factors such as temperature stability.
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Industry Insider: Album Production Series Part 3; Trials and Tribulations PDF Print E-mail
Tuesday, 17 March 2009 13:49
By John McGlasson - GJD
With the undertaking of any big project, regardless of discipline, there are going to be speed bumps, even roadblocks. I’ve had several in the last couple months. At this point, our former distributor owes me a fairly sizeable sum of money for sales that took place months, in some cases, years ago. I spent everything I had and then some to promote these artists, and with the well-documented decline of the overall music business, I’m finding myself at it’s mercy, and am having a hard time getting by, much less paying the studio thousands of dollars. Add in my personal legal issues and incurring fees, and you’d think I wouldn’t be able to continue; not the case. We all pull together, we persevere.

Thankfully, our producer, Tony, has been involved with the label almost from day one, he knows what we’re up against, and he knows the seeds I’ve planted all over the place are growing, even though we’re not seeing the fruit today. With the exception of Backyard Tire Fire’s most recent, yet-to-be-released album, Tony produced every title the band has released. BTF is on a major upward rise, their new album was produced by famed producer Steve Berlin, and will be released this summer by Hyena Records as was their previous release. I own or have rights to all titles up to the point they went to Hyena, so it stands to reason that the money is coming. Tony has known BTF longer than I have, and we share the belief in our hearts that a big payoff is coming, and soon. So Tony is willing to let me continue with my own production, and running a tab with him until the payoff comes. Without friends like Tony, there’s no question I’d be done for.
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