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Topics - culturejam

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Okay, so this is my third cheap Chinese laser engraver. The first one worked great, but was limited in carving area (a ludicrous 42mm x 42mm area). Read the long thread here, if you care:

Then I got a bigger one with a more powerful laser (2.5W) and a much larger carving area (200mm x 130mm). But, I could never quite get it properly squared up and aligned, so while it was powerful enough to burn down to metal with two passes, the second pass always lowered the fidelity of the artwork. So I disassembled it and sort of gave up (but I did keep the controller board, stepper motors, and laser module for some future project).

So now I have found a "Goldielocks" unit that's more or less in between these two. It has a similar motor system to the first smaller unit (appears to be CDROM carriage motors instead of stepper motors), and with the same power at 1.5W, but it's got double the carving area at 80mm x 80mm. And, like the larger one I had, this one does not have a platform that moves on the Y axis; it has X/Y up top and you simply free-position your cutting material underneath.

This one is *almost* big enough to do full face 125B, but if you don't need to etch all the way down by the footswitch, it will get the job done without needing to set up multiple position etching runs. But I'm sure a 2-off art setup can be figured out. Right now I'm doing some tests to figure out the native resolution so I can create some Illustrator templates.

Now some pics and comments on this particular machine:

This thing feels smaller than the original small unit, but it's actually wider (and also shorter). It has a built-in safety glass shield on the front, which is very cool (negates the need for green glasses when just checking progress).

My unit arrived (via BangGood) with a faulty laser module that would barely mark wood with laser power maxed and speed at minimum. I pulled the laser from my original small unit and it was a perfect match for this one (and works great). They offered me a measly $5 refund for the laser, which will cost me $20 to replace, but since the whole unit was only $85 shipped, I guess I shouldn't bitch too much. :)

This thing is SLOW for cutting powdercoat. Thin layers of rattle can paint is a lot faster to work with. Wood marking is pretty quick, as is leather. It can cut cardstock or very thin cardboard and paper. That's about it for cutting.

Accuracy/consistency on multiple passes is excellent. Two passes at max gets pretty deep into a thick powdercoat. A third pass yields marginal benefits over two. After that, you either have to be okay with a dark brown color, you can back-fill with acrylic or some kind of ink, or you can physically remove the last bit with a dental pick (or something similar). 1.5W just can't quite get down to metal by itself. And there aren't any more powerful laser modules that will fit this machine without major modifications and perhaps some firmware changes and/or power supply upgrades. Still, for the price vs performance, it's a good deal and a fun thing to play with.

Finished / cleaned out etch:

As with all my idiotic adventures........more to come!

Build Reports / Wacky Belton 2 Reverb
« on: June 04, 2018, 09:15:06 PM »
First full/completed pedal I've finished up in like 10 months or so. Stuffed some boards for FFX and tested a ton of prototype PCBs, but this one is the first full build I've done in ages.

It's based on my old Box of Hall schematic with some minor filtering tweaks and a trimmer to set the max amount of feedback available on the Feedback pot. Otherwise, it's pretty much the same.

I originally pitched this to Mark at Black Arts Toneworks as a product for his company, and he really liked it but ultimately didn't feel reverb was the kind of effect that fit with the brand. So I had this populated board kicking around in my "done but not boxed" pile for like, uh, 5 years, haha.

Sounds mostly like a Belton 2, which is to say there is a fair bit of modulation. But this one, for whatever reason has this really great modulation-drone sound if the Feedback is set just right. It sorts of becomes its own instrument that you can play over. I think a post-rock or noise-rock player would really get some use out of this. I'll try to do a quick sound clip this week.

Finishing was with a oddball ad-hoc mask as described here:

The guts are quite a mess, but this is just for me and I know it's solidly done, so I don't care.

Open Discussion / NuTube Amp Kit(s) -- Ideas for Brian?
« on: May 18, 2018, 05:49:27 AM »
Thought these were kinda cool.

I gotta say I would be all in on a madbean NuTube project.

Had this for a couple weeks but haven't had time to post anything. Just got some parts in for mods as well, so more to come after this.

This is a Jet City Custom 5. Single-ended octal output tube with 2x preamp tubes. The circuit is Marshall-ish but has some odd choices for values (in my opinion). I bought a mod instruction sheet that supposedly gets it really close to a JCM800 in the preamp. While I can't share the document because of copyright laws, I can share what mods I end up making. :) The guy who did the mods apparently is tight with the guy who owns Jet City, and he was nice enough to share the factory schematic with me. I may redraw the preamp section so I can share it as well. I feel like any modification instructions should include a schematic.

This is, apparently, Jet City's attempt to use up the leftover Pico Valve chassis and transformer stock. The circuit is derivative of the Pico, but definitely not the same. I believe the chassis is identical (which is also almost an exact fit for a Valve Jr.... and I've read that it's the same guy behind Jet City, Black Heard, and the Valve Jr), and the transformers are marked "PicoValve". Like the Pico, this one also has a 5H choke.

Apparently, the guy behind Hovercraft Amps did the circuit mods. Also apparently, all of Hovercraft's amps are modded Jet City amps or similar with a dressed up head cab and face plate. Weird.

As it is, the bass is flubby and loose. Same complaints as the Pico, although this one does sound better (I briefly owned a Pico, so I recall the problems with it). More gain on tap here, as the Custom 5 has bypass caps on the first three amplifier stages, whereas the Pico has none.

I'm going to do whatever I can to tighten up the bass (starting with the filter caps and then moving on to coupling caps). Other than that, I dig the way it sounds. Great hard rock tone. The boost switch is sort of odd, and in the bass setting really just doesn't sound remotely good. The only way it works is in the treble setting. I may muck with those values as well.

This thing is HEAVY!

As promised, I am becoming the JimiLee of small cheapish amps.  ;D

I have more new amps than time to post about them, but I'll do this one tonight. First entry was the MonoPrice 5W 6V6 10" combo for $99.

Tonight is the SET5 5W EL84 super-tiny head. It is $99 including shipping. Got it from here.

It is a LOT smaller than I thought it would be. See first pic below for size reference (never miss a chance for product placement!). Seems quite well made overall. OT is a little small, but I can't say I expected big iron in a 5W $99 amp.

Here's the specs:
5 watts via 1x EL84 and 1x 12AX7 (Chinese tubes, of course)
Treble, Bass, and Volume controls
1W and 0.1W attenuation modes (slide switch on rear)
8 and 16 ohm outputs

Frankly, it sounds pretty good. It doesn't have a ton of umph, but it does have a decent tone at full volume. Kinda sounds like a Valve Jr, but with a touch more gain and a little smoother. There's clean headroom with humbuckers up to about 3 or about 4 with single coils. Bass and Treble are actually useful. The 1W setting sounds pretty good with the amp cooking; the 0.1W has too much high cut and frankly isn't loud enough to do anything useful other than rock out next to a sleeping baby. Haven't tested any other tubes in there yet, but I have some in the mail. I don't expect massive improvement with different tubes, but swapping is half the fun of tube amps. :)

Internal build quality was nicer than I expected. And nothing is surface mount. Modding should be relatively easy. I have emailed the distributor and asked for a schematic, so we'll see what happens.

I noticed there are 8 or 10 1/4-watt resistors (and they are carbon film). I assume these guys did the math and feel okay with that low of wattage in certain spots. Also, the "anchor" tabs on the power tube socket were not soldered, so the socket moves more than I like when removing a tube. I will fix that shortly. Some of this appears to be wave soldered, while other components are definitely done by hand. They didn't do any flux cleanup, which isn't the end of the world, but obviously a little on the sloppy side. A few components are little crooked, but I'm being picky.

The cage is actually three pieces, and the front/back grill are removable. I'm totally going to 3D print a new badge for the front.

Overall, it's a nice little amp. Great platform for modding or doing a gut-n-rebuild. But it's also okay just as it is as a tiny amp head for practice or recording. Not a damn thing wrong with it out of the box.


Open Discussion / Ring Modulator from college physics project
« on: April 27, 2018, 12:18:30 PM »
Not sure if this has been posted already, but I though it was worth sharing. See attached PDF.

The guy used a Analog Devices AD633 Four Quadrant Analog Multiplier to do the heavy lifting. Could be a jumping off point for a new pedal project.

I had some ebay bucks burning a hole in my virtual pocket, so I figured I'd see if the MonoPrice / Stage Right 5W 8" tube combo amp was worth a damn. Best $92 amp I've ever bought.  ;D

Some of you probably know that MonoPrice doesn't actually make anything. They get private label stuff from manufacturers and resell it. But they are very good at choosing nice stuff and selling it at irresistible price points. I have one of their mini 3D printers, and it's excellent (and cheap as all hell).

Based on my readings on the interwebs, this amp is just another rebadge of the Laney Cub 8 (itself just a rebadge of some nameless non-brand amp). That pretty much means it's a Champ clone with a simple tone control added between the preamp and power amp. There is also a switch on the front panel that says "5W / 1W", but it doesn't actually change anything regarding voltage and it's not a pentode / triode switch. All it really does is add more input resistance to load the guitar pickup more. Still, it works well and doesn't have a big impact on tone. I'd guesstimate that it drops volume by about 25% and there is a small amount of overall gain reduction (which may or may not be a good thing depending on your application).

Considering the tiny cabinet and 8" speaker, it sounds very good. The output tranny is pretty small, but it doesn't seem to lack in the low frequencies. With stock tubes, it favors single coils for max headroom, as humbuckers drive it pretty early on the Volume knob (a little hair shows up around 3 on the dial). The Tone control is very responsive all the way around, but there is a big jump right near the end of the sweep (clockwise). The way Tone is set up in the circuit, it also sort of acts as a gain control as well. Between Volume, Tone, and the "Watt" switch, you can get a lot of sounds, especially if you play with your guitar's controls as well.

Stock 6V6 is Sino clear glass (6V6GT). Honestly, I think it sounds just fine. The preamp tube is totally unmarked, but the documentation says it is 12AX7. It must be a low gain 12AX7, because I swapped in a JJ ECC83 and it had noticeably more preamp breakup. I ended up putting in a JJ ECC81 (12AT7) to get a little more headroom, and it really works nice. Since I had a single, I also put a JJ 6V6 in there. I'll play that for a few weeks and then put the stock 6V6 back in and see if I can hear a difference.

The only thing I wish it had was a master volume, but it's a Champ, so there ain't one. I can probably get where I need with just my guitar volume. I think there is enough room for a 10" speaker if I cut the baffle a little bigger.

For $100 folks, this one is a no-brainer. As with many of these Asia-made amps, you can't come close to buying the parts for the asking price of a finished amp.

Open Discussion / How the JCM800 Circuit Works
« on: April 04, 2018, 06:57:24 PM »
This is a great technical analysis of the JCM800:

Just thought I'd share. It's probably already been posted here, but I don't recall seeing it.

Open Discussion / NAD: Marshall DSL20HR
« on: March 31, 2018, 10:24:24 PM »
I've actually had this for about two weeks now. Just wanted to wait to play it a few hours before I weighed in with an opinion on tone, features, etc.

Overall, I really like it. I'll break down what I see as the pros and cons:

Tons of gain on tap on the red channel, but it never gets fizzy.
Low-end is very prominent but can be mostly dialed out if desired (Bass control + Resonance control)
The tone stack is very responsive and works in a logical way
Sounds *phenomenal* when cranked and *really really good* at lower volumes...this is all on the 20W mode
It's 20W but still has EL34s, but it's cathode biased instead of fixed. So it's still got a "big bottle" sound about it without being a total beast watts-wise.
Digital reverb is pretty decent. Better than a Belton brick, but not as good as a dedicated DSP pedal or rack unit.

The green (clean) channel is what I would call "neither fish nor fowl". It can't ever get totally squeaky clean (with humbuckers anyway), but it also doesn't ever top out with a nice crunch. It goes from sorta-clean to not-quite-driven.
In the 10W mode on the red channel, the same tone is mostly still there as 20W, but there is a fair loss of high end which requires an EQ adjustment to get it close to the 20W mode. Still, it's impressive and a noticeable volume reduction. I marked this a con because I had read many comments saying "it sounds exactly the same at 10W as 20W", but I'm just not hearing that.

Not tested yet: effects loop, emulated output jack.

Other notes:
 The EL34s are JJ brand and matched (see photos below). The silkscreen says Marshall, but the shape is a dead is the JJ logo sticker on the base. :) 
 The phase inverter appears to be Chinese, but V1 and V2 appear to be JJ as well. Silkscreen markings are identical to the EL34s, and I compared the internals to some JJ 12ax7s I have, and they look nearly identical (same getter, same plate size and configuration, etc).

Enough yapping. Here's some photos.

Open Discussion / New Function f(x) demo video from Anderton's
« on: March 12, 2018, 02:24:08 PM »
Check it out, ya'll

They made a comment about us not having info about this pedals on our site, but I think they visited during a brief period last week in which we had a site problem and nothing would load.

<a href="" target="_blank"></a>

Open Discussion / Another lazy finishing technique
« on: February 25, 2018, 07:18:50 PM »
Got the idea while chasing my kid through Joann Fabric the other day. I saw these cool disk things that looked like they would make for a neat rattle can stencil. Apparently this things are called a "plastic canvas". This is pretty much the same one I used:

So yeah, just lay this thing on an enclosure and hit it with spray paint. Probably a good idea to finish off with some kind of clear coat.

Here's my first attempt. Literally took 20 seconds. The box is a Hammond pre-powder-coated. Paint was some kind of random white that I had laying around. The lines aren't clean at all, but it's hard to get that when the enclosure itself isn't flat. I'm sure there's a way to make it sit flatter, but this was a first (lazy) try.

We cut the cord here at the 'Jam household back in June, and frankly I'm not really missing anything. We signed up for PlayStation Vue and generally like it. It's not perfect, but we get almost everything we were watching on cable (all the "critical" content, with the exception of The Daily Show) and we're saving about $60 a month...and that includes HBO as an add-on. What's more, the HBO on-demand catalog is so much deeper on Vue than what we had with our cable box. Also, having Netflix, Amazon Prime Video, and PBS Kids all integrated into the same device with PS Vue is just so convenient.

The biggest gripe we have is that the way the DVR works is not all that awesome. It's not really DVR in the traditional sense, actually. You can add a specific show that you want to record, but it will record ALL of that show. You can't just record one episode. Also, if you want to start watching from the beginning of a show that is being recorded (live), you first have to go to the current time and then you can play from the beginning. This sucks for sports or anything with spoilers (ie - any show with any sort of plot).

Maybe the worst is that you can only pause live TV for 4 minutes. That's nearly a useless amount of time for pause, at least for people with small children.   ;D My cable box could pause for 2 hours, and it was 8 years old. But, I'm doing all the PS Vue stuff through a Roku, which has no local hard drive to dump on.

My internet is 65Mbps down and about 25Mbps up. The cost is ~$65 a month. I ask about this because I'm curious what others are getting / paying. Once you cut the chord, MB is the name of the game.

Open Discussion / A bit of ornamental fun
« on: November 28, 2017, 08:14:40 AM »
I saw some empty plastic ball ornaments at the craft store the other day and decided to make some bead-filled ornaments with the little one. But then I thought, what if I fill one with all the parts in my breadboard bin that I know I'll never actually use again? (I always say I'm going to reuse the resistors, but with my free time ever-dwindling, I just don't bother hunting anymore).

Turned out pretty good, if not damn heavy. I threw just about every kind of part we use to make pedals in there, including germanium diodes and transistors, a BBD, a VCA, an OTA, op amps, transistors (including JFETs), knobs and switches, and even some surface-mount digital stuff. I think I maybe forgot an inductor, but I think I have some small axial ones I can cram in the top.   

Open Discussion / Function f(x) - Newsletter
« on: October 25, 2017, 09:16:59 PM »
Just thought I'd let you guys know that we (Function f(x)) have set up a newsletter system-thingie on our web site. Certainly don't feel obligated to sign up, but if you want to, here's the link:

We're planning on no more than 1 email per month. The main purpose is to announce new products, do promotional stuff like giveaways and coupon codes, and let people know when we have one-off or b-stock pedals available.

The only info we are collecting is email address. So apart from letting people know what we are up to (and giving stuff away), there's not much nefarious we can do with just an email address.  ;D


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