tag:blogger.com,1999:blog-5570761091300290332012-01-09T10:03:13.386-06:00New use for old technology.Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.comBlogger221100tag:blogger.com,1999:blog-557076109130029033.post-74200271393586874962011-07-03T11:56:00.017-05:002011-07-03T13:02:32.776-05:00

Supposedly the electronics in the original Danelectro guitars were very heavily shielded. When I bought this reissue '63 Dano baritone, I was more than a little disappointed that aside from the "lipstick" pickup covers, the instrument was practically unshielded. The back of the pickguard had a skimpy little strip of aluminum tape between the controls.It wasn't a great surprise though, as this is

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com1tag:blogger.com,1999:blog-557076109130029033.post-57568752211969663232011-03-23T20:00:00.001-05:002011-03-25T16:41:28.320-05:00

Do you have a desire to build a fractional-watt miniature solid-state guitar amp? Apparently many people do, since there are several schematics out in the wild on the DIY discussion boards. For some reason, they tend to be built around little "chipamps" like the LM386 and its successors. They work off a 9V battery and are pretty easy to build. Make magazine even featured one version that was

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-37852866310130367872011-03-08T05:22:00.002-06:002011-03-08T05:25:04.742-06:00

The first commercial recording using this amp was released on 3/8/2011:I play rhythm guitar for this track on my Yamaha RGZ-211M through the BoxHead, mic'ed with a Nady ribbon.BoxHead Amp - Finished a photo by OakBloodThree on Flickr.

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-89217122979689726642010-03-14T19:46:00.006-05:002010-03-14T20:12:39.497-05:00

Last Christmas, I got my wife a Creative Zen X-Fi 2 media player. It came with one game, Sudoku and the Creative labs website didn't have any others to download; recently a little searching showed that they had released an Application Development Kit for the player. The kit is really just a simulator and a document describing the API. Programming on the X-Fi 2 is done with the text esditor of

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-36385215374107715882010-02-22T19:48:00.000-06:002010-02-22T13:49:15.511-06:00

One way or another, the next major project will probably involve microcontrollers. A few possibilities:Reconfigurable tube guitar amplifier: An amplifier has a mutable topology that is be at least as flexible as a typical channel-switched amp, but with fewer signal-path components. The microcontroller is there to keep track of valid topological arrangements and operate relays and softswitches.

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-8574274985107143202009-10-25T08:32:00.007-05:002009-10-25T14:37:26.479-05:00

Here's a video with images of the BoxHead inside and out, with a soundtrack where all guitars are played through the BoxHead:

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-34127203862871186882009-10-18T12:57:00.004-05:002010-06-11T14:36:39.839-05:00

The long-awaited 2 × 6973 amplifier has been essentially done since April, and it’s called BoxHead. I held off on this post as it was undergoing occasional adjustments since then. Here’s a rundown of the design:Power supplyThe power transformer is a “semi-custom” unit from Edcor. Although it’s not a standard model, it was a custom configuration requested by a previous customer, so Edcor

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com1tag:blogger.com,1999:blog-557076109130029033.post-22022470604745078482008-12-01T15:00:00.012-06:002008-12-01T15:12:22.332-06:00

Here's an update on the Foray into Furniture:The first photo is an overall shot, including the CPU, Digi 003 rack interface, monitors and wall-mounted display. All the wood is cherry; the top is 3/4" plywood with veneer banding on the edges. The sides and back are 1/4" plywood. The CPU shelf is 1/4" solid cherry. The rest is solid cherry 1×2s. I used a tongue & groove router bit to make the

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-25457243206753643682008-11-21T20:00:00.006-06:002008-11-21T20:00:01.030-06:00

It may be a while before concrete evidence of the next electronic project shows up here, but here's a little teaser and progress schematic for the next amplifier, the Lama Kazu 12PP. It will be a 15-ish watt push pull with 6CM6s for the output (they're 6V6s in noval bottles). The preamp will be:Input -> 6AU6 -> Gain control -> 12AV7 gain stage (DC-coupled between sections) -> Tone stack (

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-55909525397353179922008-11-20T20:00:00.001-06:002008-11-20T20:00:00.996-06:00

Have you ever seen a piece of furniture for the home recording studio that meets the following criteria?Compact footprint for use in a small room.Work surface elevated for comfortable use of keyboard & mouse while standing (with guitar strapped on).Computer CPU elevated so that a vacuum cleaner can go under.Enclosed sides to help contain CPU fan noise.Includes a storage drawer.No

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-71451979544736077092008-11-03T20:00:00.001-06:002008-11-03T20:00:00.645-06:00

You already use Duncan Amps and NJ7P to find tube datasheets. Here are a couple browser search plugins I made to make it easier:NJ7P plugin.TDSL plugin.

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-84937163065489353422008-10-20T20:00:00.001-05:002008-10-20T20:00:00.169-05:00

I started out with the idea to make a tube DI box for the '63 Dano Baritone guitar I ordered. It turned out that the Dano was long delayed and the order was eventually canceled, due to some manufacturing problems. I continued with the project as a bass DI. I threw in a microphone input for laughs. The circuit evolved.A starting point was the Altec 1566 preamp. I wanted a pentode input, so I

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com1tag:blogger.com,1999:blog-557076109130029033.post-21357323427944032602008-09-27T06:34:00.016-05:002008-10-10T14:07:55.384-05:00

I won't spend any time with the background on the Kalamazoo Model 1. It's all available at Miles O'Neal's Kalamazoo Field Guide. Here's what I did to improve our Model 1 and why:I added a power input module. This includes an EMI/RFI filter, and moves the power switch to the back panel, and off of the tone potentiometer. The original front-panel fuse and neon remain.Volume and tone

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-63679050736271990062008-06-08T13:44:00.005-05:002008-10-20T09:28:03.074-05:00

The tweaks to a simple single-ended amp could be endless. I think this will be the last adjustment to the Lama Kazu 8SE, however. (Note: It wasn't! Some edits to this post were made in October.)I decided to try a 12BZ7 in the second gain stage/cathode follower. Of course the bias had to be adjusted for that. Not knowing how exactly the 12BZ7 would act at clipping, I decided to add a small (

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-35629502040720137542008-05-24T08:00:00.011-05:002008-05-24T08:00:00.865-05:00

I started out wondering: "How variable are JFETs? How many parameters must be measured when selecting them?" I ended up with a grungy overdrive/distortion: the Stupid FET Trick.Looking at the 2N5457 datasheet from Fairchild, you can see that drain saturation current (IDSS) and gate cutoff voltage (VGS(OFF)) are correlated: I've seen other methods on the web for selecting FETs to use in audio,

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-7313042518816158572008-05-17T08:00:00.006-05:002008-05-17T08:00:03.376-05:00

While performing inventory of my parts bins last fall, I came across a couple ancient-looking TO-1 metal cans. I have no recollection of their origin, but the leads were rather short, so I presume I cut them out of a junked radio or similar item, probably when I was a pre-teen. At first I presumed I acquired them at the same time, but it turns out they're from different manufacturers, so maybe

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-68507031710061903332008-05-10T06:00:00.003-05:002008-05-16T08:54:43.520-05:00

Recently, I mentioned in on an online forum my idea for a 15-ish-watt amp based only on Compactrons with a 6AS11 preamp and a pair of 6LU8s for the power amp and phase-inverter (each tube contains a beam tetrode and a medium-μ triode). One response was: "You should get a job with Metasonix". I suppose I could have taken offense at the comparison: While I think there is a place (and probably a

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-38649664756504461622008-05-03T02:00:00.004-05:002008-06-01T17:00:46.855-05:00

The Lama Kazu 8SE was revised last fall; I never got around to mentioning it here until now. The revised schematic is at right. Most of the changes were to reduce the gain, smooth out the overdrive character and clear up some blocking distortion.V2 was changed to an ECC832, (JJ's equivalent to 12Dw7) with the high-μ triode at the input and low-μ triode at the driver stage.V1 was changed to an

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-62832963199593022272008-04-30T08:00:00.001-05:002008-05-13T19:43:32.585-05:00

A beta-test version of my Treble Peaking Filter Calculator is now on-line (graciously hosted by tafkad.com)! What it does is calculate the resistor and capacitor values required to make a high-pass shelf filter with specified turnover frequencies.If you use this in the early stages of an amp or distortion circuit, before any overdrive or clipping actually occurs, the concept (and circuit) is

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-25978634887517688062007-09-04T14:33:00.000-05:002007-09-28T10:37:47.636-05:00

Some of the woodwork is finally done. Here are progress photos:Treble end:The edges have been routed to receive guitar bindings. Unfortunately the router took off some chips of the surface veneer which will have to be repaired before the bindings can be attached. Holes on front will receive grommets.Bass end:Bellows frame:Treble end with bellows frame, handle and palm rest (mock-up).Valveboard

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-78796008298174304292007-07-17T10:29:00.001-05:002008-10-10T14:28:24.159-05:00

It started as an attempt to create something like the Kalamazoo Model 1, but with more gain, better tone control and a master volume.Summary:Single-ended, ~8W RMS (Clean); ~11W (Full distortion).Preamp tubes: 2×ECC83. Power tube: 1×7591.Speaker: Jensen C8RCabinet is FSC-certified pine, finished with Tried & True wood finish (hand-rubbed Linseed & Beeswax product). Grill cloth is Marshall "cane".

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0tag:blogger.com,1999:blog-557076109130029033.post-45292617328451293022007-03-22T14:27:00.000-05:002007-04-30T12:10:28.649-05:00

The project began in 2000 with the closing of Star Concertina in Cicero, IL. Much dreaming ensued about carrying on the tradition of [Chemnitzer] Concertina manufacturing in Chicago.A bit of tinkering with old boxes followed.Some conversations were had with John Bernhardt:What was done by Star in-house.What was outsourced.How some construction details were realized.Where materials were

Theodorehttp://www.blogger.com/profile/16307400694831257099noreply@blogger.com0