Tweak Notes

[ last update: 30April2006 ]

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Murgatroid(?) scheme A

Murgatroid(?) scheme B

Murgatroid(?) scheme D

New Work Table

[ 06Mar2006 ]

All that talk about workshops (see below) got me thinking about how I could make mine a little better, and the number one thing on my list turned out to be some kind of work table on wheels. I originally thought I'd just get a relatively cheap utility cart, but I couldn't find anything with all the right dimensions (or that seemed appropriate for hacking to the right dims).

After some hanging out in office supply and hardware stores, I decided to bite the bullet and go for a fully custom solution - a Craftsman toolbox on a furniture dolly, with a 32 x 18 inch wooden top.

I present to you the Harmonic Appliances Toolbox Table:

closedopenwith v2 proto

"Workshop" Photos

[ 31Jan2006 ]

This is my response to the "Post Your Bench Pics" thread over on the AX84 BBS. I couldn't believe how neat some of those guys' shops looked! These pix were taken soon after a fairly serious cleanup, BTW...

These shots are all of my home "office" (I sometimes actually work from home), that's also my electronics bench, library, music room and parts department (just about my whole life!). The only things that don't happen here are the woodworking and larger scale metal work (more than a hole or two). That stuff happens in the garage, after I kick my wife's car out for the duration.

These snaps all link to larger versions. Can you find the Verberator II prototype?

The work area:

The mighty heap o' crap:

The new (Nov05) sax:

The Pods are taking over!

[ 28Aug2005 ]

Thanks to Alan Watson (AKA "Knob-head"), I now have way cooler knobs for my Verberator, and many future amps. He calls this shape the "pod" and the finish "gothic." In addition to the large pods shown above, I also bought some smaller pods and "thorns."

Here are a few more pictures of the new knobs, both on the amp and off:

     Most of the Verberator front panel.

     Tone & Reverb controls.

     All three knob types that I bought.

The thorn knobs will eventually be used for impedance selector switches, and I expect to use some of the small pods for things like tone and/or reverb controls on amps that don't have a lot of front-panel space.

If you're interested in building amps with a look that stands out from the crowd you should definitely check out – Alan's got some great designs, and it was a pleasure doing business with him.

O frabjous day!

[ 07Nov2004 ]

Yippee! I've been slowly debugging a fuse-blowing problem with the Verberator. Yesterday I not only found & fixed it, but in the process almost completely eliminated the 120Hz buzz that I've never been happy about (I felt pretty much forced to use the highest NFB setting).

The fuses were blowing because I had a dead rectifier diode, which was easy enough to fix once I found it. I had been cheap/lazy the last time I tinkered with the PSU section (to put in UF4007s with R+C filters across them) and used only one diode for each side, so my guess is that the power-on surges were just too much. Now there's a pair of UF4007s on each side, but the R+C filters are gone (latest schematic here).

In the process of fixing it, I happened to re-route the wire from the diodes to the first filter cap, and my 120Hz buzz went away! Is that a great bonus or what? Now, even with NFB turned off the Verberator is quieter than it used to be on the maximum NFB setting. My lucky day...

Sax and Violins

[ 07Nov2004 ]

A week ago I had a bonus burning a hole in my pocket, so I went out and bought myself a Tenor Sax. I've always loved that sound, and have been seriously thinking of getting one for the past two years, so I decided it was time to take the plunge.

It's really easy to get the basics going, but I'm pretty sure I'm going to be taking some lessons. If nothing else they should help prevent the formation of bad habits. Also, scales on the sax are wierdly "non-linear" in a way that's gonna need a lot of practice to get used to...

[I've had a violin for ages, but they're so much harder to play in tune!]

Introducing the Highway 86

[ 07Nov2004 ]

My only complete build of the past year has been the Highway 86. The original idea came from the "Hwy-86" schematic that I offered to host for Aharon Colman (met via AX84) back in June. It's intended to be a low power "Route 66" based on a pair of ECL86/6GW8s, with a 6AU6 in front.

I'd been planning to do something with either 6BM8s or 6GW8s for a while (and acquiring tubes and suitable trannys), so I already had 90% of the parts on hand. Aharon's schematic called for a different rectifier, but my Highway 86 is basically just his circuit with a master volume and indicator tube added. The final schematic is here.

I'm not ready to put up a project page yet (see below, and also I haven't got around to recording samples), But here are a few things to look at in the mean time...

Not dead, just busy...

[ 07Nov2004 ]

I never thought I'd be updating this every day, but going a whole year is a little ridiculous. I've partly just been busy, but I've also been feeling that I should put my site maintenance energy into a re-design before I 'publish' another project (I've built a parts guitar and an amp already). We'll see...

Verberator Update

[ 09Nov2003 ]

I've known for a while now that there was a mistake in the preamp of my Verberator, but haven't had a chance to open it up (it's been sitting in my brother's studio, where I get to play it as loud as I want).

The symptom was that the Verberator tone controls worked great except when the Bass pot was turned up past 60% rotation. If you went past 60% Bass, the tone was abruptly deadened. It didn't really bother me (I rarely have the urge to crank the bass that much, so I wasn't prevented from using it), but I knew it was wrong and wanted to fix it.

After a few more months of hanging out at Ampage & AX84, and an email from a very helpful guy by the name of Robert Manktelow, I was sure that the problem was that there was no decoupling capacitor after the cathode follower in the preamp (triode V6B). Today I finally got the chance to install the missing cap (C33, on page 2 of the Rev. F schematics). I'm happy to report that the control now works perfectly over the whole range.

Other aspects of the Verberator have been evolving, too. A few revs back I changed R16 (in the Direct Out section on page 4) to 100k. Definitely an improvement, as it puts the pot in the middle of the voltage divider.

I've also switched to 2k2 screen resistors on the EL84s, mostly because folks were recommending that for similar circuits over on Ampage a while back – no obvious difference, to these old ears. In addition, I've latched onto some Soviet 6Π14Πs (sometimes written as 6pi14pi or 6P14P), which are supposed to be direct replacements for EL84s. I haven't done a serious comparison yet, but they seem at least as good as the JJ tubes that were in the Verberator first. Maybe a taste test will be my next posting…

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