DIYTube Budgie SE 3W Single Ended Amplifier

Our good friend Shannon Parks over at DIYTube has designed another great tube-based amplifier, this one using a pair of EL84 power tubes and a single 12AX7 driver tube.The Budgie has been designed from the ground up to be an affordable build, the power and output transformers (sourced from Edcor) run a measly ~$100 or so dollars for all three! Throw in the parts ($35), tubes ($35), PCB ($39), and build your own chassis ($20), and you should be able to scrape by under $250. Granted, this would be a bare bones build, but it just goes to show you that this is an affordable design. You can go hog wild and add Shannon's top custom printed top plate and a Hammond chassis with walnut sides, and maybe some boutique coupling capacitors, and we're still looking at a reasonable price tag for a single ended tube amplifier.

Budgie SE with custom printed top plate and walnut sides

The DIYTube Budgie SE Schematic

I chose to skip the top plate as I enjoy building my own chassis (it prolongs the whole building process which I find inherently enjoyable anyway). I had a scrap piece of copper which I trimmed to 7" x 12", which is a little larger than the custom printed PCB and will allow a little more air between the components. The base would be an intricate mitered wood frame made from chair rail molding from the hardware store. 

The copper plate was cut, punched, drilled, Dremeled, etc. to hold all the parts in place. The layout used to plan the initial plate size was used to determine where each hole would fall. Small holes were drilled using the drill press, larger holes for tubes and the Neutrik locking plug were punched using GreenLee punches, the extra-large holes for the capacitors were cut using hole saws on the drill press, and square holes, like for the transformer and IEC inlet were cut using a Dremel metal cutting disc. The copper is a little denser than aluminum and requires a bit more effort to cut through.

Once the chassis plate had all the holes necessary to accommodate the parts for the build, it was sanded down, starting with 80 grit sandpaper and ending with 600 grit. Next, a coat of clear satin finish was sprayed on each side to protect the copper, otherwise it tends to pick up fingerprints and oxidize. I've had good luck with the clear satin enamel from Krylon. I tried the Valspar outdoor clear satin and it clouded up and flaked off, so I won't be using that again. Gloves needed to be used after the sanding process so my fingers wouldn’t leave any oil on the copper. Once the clear coat was dry, parts could finally be fastened onto the plate.

Copper Plate with myriad holes

First the various connectors and jacks could be installed. The RCA females are nice quality Philmore gold plated units with a Teflon dielectric. The binding posts are generic heavy duty gold plated brass with clear plastic on top, made to look like WBT's early binding posts I assume. Also installed is the ubiquitous Neutrik 1/4" TRS locking jack, which I elected to install with the release up front for ease of use, the IEC inlet with built in fuse, and a small toggle switch for power.

The Budgie gets some cost effective connectors

Populating the PCB were a number of parts I had lying in the parts bin, some Koa Speers resistors (green) from Mouser, and some spiffy Elna RFS Silmic II electrolytic capacitors from Digikey. Both the Koa Speers and Elna Silmics are considered to be "warm" sounding parts (the opposite of bright or harsh), which is usually what I'm going for. The big blue caps are 150uF Cornell Dubiliers that have good ripple current ratings, which will help smooth the power supply a bit in addition to the Triad choke called for in the design. In addition, I added some surplus Nichicon 0.1uF film caps bypassing the power caps, which would help ripple to some minor degree as well. I also found some oddly shaped Mundorf EVO Aluminum 1uF film caps that I installed on the side of the board. These were relatively low cost and a bit more interesting to look at than a standard film cap.

Top of the PCB with Tube Sockets, Film Caps

Bottom of the PCB

The PCB could now be fastened to the copper plate with short aluminum standoffs.

Directly beside it would sit the 1H Triad choke which I pulled from an ST70 when I upgraded that choke to Classic Valve's heavier duty model.

Sitting directly beneath the output transformers are a pair of matched vintage Russian silver mica capacitors. If a manufacturer was making these today, I'm sure they'd be pricey, but given that they are old military surplus, they're downright affordable. Some audiophiles feel these sound comparable to the Russian Teflons, so I figured I'd give them a shot. They are certainly interesting looking little metal brown boxes.

Check out those Russian silver mica caps!

With all the small parts in place, I could secure the Edcor power and output transformers. I purchased some unpainted bells from Edcor (I'd imagine these are popular products on their page for anyone who doesn't want blue) and had them powdercoated with an antique copper color, then replaced the nylon washers and the nickel hardware with brass for a more uniform look. These were secured to the copper chassis with rubber washers to dampen a bit of the vibration they produce.

You can always hide a depth mounted screw under an xformer

Since a copper plate cannot sit on its own, a wooden base was fashioned out of some decorative molding from the hardware store, the edges rabbited with a router so the plate could sit on top via "gravity mount", and then mitered to be a perfect fit for the plate. Once the four pieces of molding were secured together with woodglue and allowed to dry, I went through the process of copper leafing and antiquing the wood. If you'd like to see more details on this process, please check out my Bottlehead Crack Coppermine project.

Completely wired up

And the photos of the finished unit:

Front

Rear

I had a listen with a pair of Sennheisers and really enjoyed the quality of the headphone output. I'll be testing the unit with some speakers shortly. Looks like Shannon has another winner on his hands!

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind. 

Budgie Cinemag MC Step Up Transformer (SUT)

The Budgie Cinemag MC Phono Step up transformer (SUT), phew, that's a mouthful. If you haven't been initiated into the wonderful world of vinyl, or even if you have, you might not know what all that means, so I'll do a quick clarification.

The Budgie series is Shannon Park's series of audio circuits that are designed around offering both great sound and reasonable pricing, Budgies for audiophiles on a budget. These include phono pre-amps, single ended amplifiers, step up transformers, and more. Cinemag is an american maker of fine audio transformers for microphone, phono and other applications. MC stands for moving coil. Many record players include MM cartidges (moving magnet) which have a higher (louder) output than moving coil cartridges. Many of the most high-end cartridges, as well as the immensely popular Denon DL-103, are moving coil.

A step-up transformer, or SUT for short, is needed to bring the low output level of moving coil cartridges up to the level of moving magnet cartridges, so one can use a traditional phono pre-amp for pre-amplification purposes. The SUT is plugged in right between the turntable and the phono preamp. Granted, there are phono preamps with both MM and MC capability, but they're not as common as the standard MM phono pre, which many audio enthusiasts are likely to already have.

Enter the Parks Audio Budgie Cinemag SUT. If there is beauty in simplicity, this design is Kate Upton in a bikini. A pair of load switches (MC high at 141 ohm load for medium output MC cartridges and MC low with a 35 ohm load for cartridges with a low output [less than 0.2mv]) and a ground lift are the only controls adorning the unit. Other than that, you have the input RCAs, output RCAs and ground binding post and that is all she wrote.

The attractive Budgie SUT board

Internally simple as well, only 48 solder points are required for an operational unit, including eight for each MC transformer, eight for each switch, and two for each RCA. Only twenty or so parts are necessary, including the PCB, the RCAs, the transformers, the switches, the screws, the black aluminum box for shielding purposes, and the feet.

Hammond alumminum chassis painted black

Cute little isolation feet

The Budgie SUT will work with three different Cinemag transformers, depending largely on your budget. (The pricing listed is as of this writing, Feb 2014 and may be different by the time you order.) You'll need two transformers, the CMQEE-3440APC runs $50ea, the CMQEE-3440AHPC runs $75ea, and the CM-1254PC runs a whopping $175ea. For differences, see below statement from the Budgie manual:

“The CM-1254 was designed specifically for moving coil phono cartridges. The CMQEE-3440A was originally designed for Quad Eight for microphone and line input to their preamps. The CM-1254 is much more difficult to make than the CMQEE-3440A and, hence, the price difference. The CMQEE-3440AH uses laminations which have seen collected over many years for characteristics which are optimal for
moving coil applications. We use the same laminations for the CM-1254.”

For this particular build, I used the CMQEE-3440AH PCB version with the nicer lams.

Cinemag CMQEE-3440AH transformers - PCB versions

In addition to the nicer lams, I added a set of Vampire RCAs with Teflon dielectric (below) and a Vampire binding post for the ground connection (seen above next to the transformers).

Vampire chassis RCAs

Thanks to the simplicity of this design, one won't need the little isolator rings or the ground rings that come with the RCAs, although it's always wise to save spare parts like these for later use.

Ground and isolation rings not needed

The RCAs (and ground binding post) will simply be screwed in the existing holes on the PCB, which effectively grounds them to the board. You'll need a small wire to run between the RCA signal and the solder pads on the PCB. For this I chose to use some Cardas 5Ns silver. A little bit of fashioning is necessary with a pair of needle nosed pliers for the solid core silver to give it the right form.

Silver wire looking like a deformed paper clip

Before soldering in the Cinemags, I chose to lay down a piece of electrical tape on the board, then poke the pins through it. This would help ensure the solder would not leak through the PCB holes while hot and short to the transformer housing.

PCB with electrical tape in place

Each of the little switches is soldered in place, and I put a dab of solder on the ground post as I didn't want it to loosen over time. The board was then cleaned up with some isopropyl alcohol and a toothbrush, followed with a few dabs of a towel (do note the black coloring on the PCB may bleed a little bit).

Holding the board to the chassis are some size #8 machine screws. I went with brass to match the mostly gold look of the unit.

This is a great little build from Shannon Parks and a bit more straightforward than using vintage microphone transformers or the wired versions of the "can" transformers.

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind. 

DIYTube Get Set Go 300B Headphone Amp

It's been a little while since the last post, and there's a good reason for that; I've been gathering parts for a very special DIYTube Get Set Go made specifically for the Audeze LCD-2 headphones. The Get Set Go is a single-ended triode design made first-and-foremost for high-sensitivity speakers that only need a few watts to fill a room with sound, such as the Planet 10 Audio Frugel Horn. I did have the fortune to build the Get Set Go for speakers previously and was impressed with the overall tonal character and quality of the sound.

The Get Set Go Board from DIYTube

You may be wondering why someone would be using a speaker amp for a pair of headphones. A typical headphone amplifier will output relatively a small amount of power compared to the speaker amplifiers (in small fractions of a watt measured in milliwatts). The Audeze, as well as certain other planar magnetic headphones like the HiFiMan, really benefit from some added wattage to sound their best as they aren't the most sensitive drivers. Hense, using a low-powered speaker amplifier makes sense, but there are some changes that are necessary.

The biggest change is the output impedance. While speakers are typically 4, 8 or 16 ohm, headphones often range between 32 and 600 ohm. The Audeze headphones that the amplifier is being made for are 50 ohm (although I have also seen them listed as 60 ohm). Since 50 ohm single-ended output transformers don't really exist on the market, you can either have one custom wound, or try and find something that would have an equivalent turn ratio. There's a handy calculator that Shannon of DIYTube recommended that will give the equivalent turn ratio for this purpose. A 3.5K / 50 ohm output transformer would have a turns ratio of 0.12, or 8.367:1. Gery at Transcendar offers a 1.6K / 16 ohm single-ended transformer, the TT-023-OT, which is a 10:1 ratio and close enough for our purposes. Per Shannon, The reflected load would be a touch more linear and lost max output would be minimal.

Secondly, learned from previous experiences like with the Millet Jonokuchi, and to a much lesser extent, the ECP Audio Torpedo, headphone amplifiers do not like their output transformers to be close to the power transformer. When they are too close in proximity, there is something called flux interaction when the magnetic waves interfere with one-another and cause an audible hum with certain headphones. So not only will the output transformers be moved to the opposite side of the chassis, but rather than using an EI transformer for power, a toroid will be used instead as they create much less of a magnetic field. Antec is one of the few manufacturers out there that builds certain toroids specifically for tube amplifiers. The Antec AS-2T300 would be a good substitute for the PA774 with a bit higher ratings.

So other than the transformer choices and their position, this build will be fairly similar to the previous Get Set Go. To make things a little different, 300B tubes will be used rather than 6B4Gs. Also Mundorf Silver Oil capacitors will be taking the place of the Jupiter wax paper caps. The Mundorfs should be a little more detailed, which the Audeze can benefit from with their warmer/darker presentation.

The first action-item on the list was the chassis. I always like to create a virtual mock-up of the chassis layout to see different set-ups and settle on what I feel will work the best. Note that in this layout, the output transformers are distanced from the power toroid and chokes.

Virtual Chassis Layout

Once this is settled, I forwarded the dimensions over to Keith (ebay seller po1019) to fabricate the chassis. The virtual layout is then used as a guide to lay out the parts, take measurements and make markings, and ultimately start drilling / cutting away. After prepping a number of aluminum and steel chassis, I have a small collection of very handy Greenlee punches, which are ideal for making clean holes for tubes and sockets. The metal area (which will be behind the little red tab on the Neutrik locking plug) to release the headphone plug was recessed a bit by sanding using a Dremel and by hand for adequate clearance.

The prepped aluminum chassis

I decided that this chassis would have a more unique and artistic finish. Something more worn and rustic looking. I was actually inspired when I was scrapping off the dark grease on an old baking sheet. This finish starts with some black engine enamel that is then sanded and scrapped by hand minutes after spraying. It produces and interesting texture in my humble opinion.

Textured Bottom Plate

Texture Detail

The texture is achieved by hand using worn out sandpaper at different times of paint dryness, along with the sharp point of a scissor to get the longer lines. Once the texture was where I wanted it, I gave the chassis two coats of clear satin enamel. The parts can now be dropped in place. I began with the smaller pieces, including the headphone sockets, which were flush mounted and secured with black oxide screws. The switch, pilot light, RCAs, binding posts, IEC, Teflon 300B sockets and hole grommets were all installed next.

Part installation on the chassis

Next comes the fun part, the population of the PCB. Varying from the BoM, we have Elma Silmic II caps, Nichicon FineGold caps, Kiwame and Mills resistors and Mundorf Silver/Oil Caps. Slight changes to the circuit includes the Wima 0.1uF snubber cap and a pair of Solen 630V 5.6uF bypass caps in the power section.

The populated Get Set Go Board

On the bottom of the board, at Shannon's suggestion, we have a few of the Mills power resistors to help distribute the heat a little better. 

Bottom of the board

Now comes the long process of preparing the wood side panels. I decided on an antique silver leaf finish for these pieces. Since there is no off-the-shelf option for antique silver leaf that was readily available, I'm using some Speedball brand silver leaf pieces and some Old World Art brand leafing and antiquing materials.

Leafing Materials

Below are the wood side panels for the chassis before any prep.

Wood Chassis Panels

The first step in the antique leafing process is a red basecoat. This is typically used with a gold foil, so we'll see how it performs with silver. Below is the wood with the basecoat applied.

Red antique basecoat

 After two basecoats and a layer of adhesive size, the wood is covered with the silver foil sheets. This is a very unusual process, the foil is incredibly thin and will tear apart if it catches your fingers, so you have to be delicate. each foil sheet is laid down with a little bit of overlap.

Silver foil sheets laid in place

The foil is then burnished with a cheesecloth to have it form the curves of the wood. This is a messy process and the foil flakes will end up everywhere. They are so thin that you'll find them floating in the air. Once this is complete, a layer of sealant is used to protect the foil. 

Silver foil after burnishing

The antiquing kit included an antique glaze that is made for gold so it's a brownish hue. It didn't look right on the silver. Instead I chose to rub it down with powdered graphite before sealing it again. Then two layers of satin clearcoat were added for additional protection of the finish.

More to come

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind. 

DIYTube 6L6 Clementine Single Ended Tube Amp

Shannon Parks, owner of DIYTube, has made a number of projects available since 2003 when the DIYTube ST35 clone was made available. DIYTube is both Shannon's small business located in central Illinois and a close-knit forum featuring a handful of helpful and prolific members. Projects on DIYTube include the 60 watt Eiclone amplifier to driver boards for Dynacos to stand-alone single-ended amplifiers like the Clementine and Get Set Go. The projects are all well documented and feature circuit boards for easy building.

The Clementine can be configured to use with 1626 Darling tubes (hence the cute name... oh my darling Clementine) to output 3/4 of a watt or with 6L6 tubes (equivalents: 6L6GC / 807 / 1625 / 6BG6) for a fruitful yield of 5 watts (see what I did there?). This post is dedicated to the building of the 6L6 Clementine.

DIYTube Clementine Schematic

The transformers used for this build aren't quite as fancy as the Transcendars found in the Get*Set*Go build, these would be the tried and true Edcor XPWR005-120 power and GXSE15-8-5K outputs. If you aren't familiar with Edcor, they're likely one of the best-value transformer manufacturers in the U.S. They've been around since 1971 and have been offering distinctive "True Blue" transformers to hobbyists for decades. All of their transformers are made-to-order, so there's usually a 4-6 week waiting period before you get your order, which really isn't so bad considering their pricing.

Edcor power and output transformers

Deviations to the BoM (bill of materials) include the typical Kiwame / Koa Speers carbon film resistors, along with a pair of matched Mundorf Supreme 0.22uF capacitors. Barely squeezed in was a pair of 100uF 100V Elna Silmic IIs. Also packed in was a little bit more capacitance in the power section using 150uF caps and a pair of 2.2uF Solen film bypass caps. Lots of green and red on this board, looks like Christmas time ;)

Top of the populated Clementine board

Important to note is the 8 pin sockets need to be carefully lined up before and during soldering. It's possible to end up with them at a slight angle, which will cause the tubes to jut out at an angle on the top of the chassis. With a bit of heating the joints and shifting, I was able to get them nice and parallel with the board. Once everything was placed, a nice scrub-down with a toothbrush and rubbing alcohol was in order to get all the rosin flux off the board.

Bottom of the populated Clementine board

For the chassis, Keith (po1019 on Ebay) fabricated me a very nice one made from aluminum and walnut side panels. Keith's work is very professional and I hope to continue using his chassis for my future endeavors.

Custom chassis with walnut side panels

One of the more time consuming parts of a build is creating all the necessary holes in the chassis using a combination of the drill press, Greenlee die punches for the tube holes and a Dremel cutting disc for the IEC inlet. Below is the chassis ready to head over to the powdercoater.

Prepped chassis top plate

Chassis bottom plate with vent holes

The chassis was then powdercoated a nice cream color. 

Powdercoated Clementine Chassis

...and the transformer bells a dark red. The transformers also got some brand new nylon screw insulators and brass hardware. I'm not sure why, but often times the nylon insulators that come with transformers are worn looking and discolored. This process is a decent amount of work. The original hardware has to be removed, the bells sanded and taken to the powdercoater, the nylon insulators squeezed into place, then the brass screws trimmed down to fit, then the acorn nuts tightened in place, all for the sake of presentation.

A beautified Edcor transformer

The next task is to add some rubber grommets to the chassis where the wire from the transformers runs inside. This is to protect the wire from rubbing up against a potentially sharp edge on the hole and shorting to the chassis metal. It's an added precaution for the sake of safety. 

Rubber grommets on the chassis holes

The next process was to add the switch, pilot light, power inlet, signal input RCAs and output binding posts. The RCAs are Cardas GRFA, the binding posts are Cardas Economy ACBP, which are still on the pricey side in my humble opinion but not as much as the CCBP copper posts I typically use. Nearly all these items are installed with a socket wrench.

Chassis-mount items in place

The PCB and choke were then installed. The PCB was installed using standoffs, screws and lockwashers to prevent anything from coming loose down the line. The choke was installed using rubber washers underneath to damp any vibrations from making their way to the chassis, along with size #6 hardware.

Chassis and PCB in place

Next the Edcor transformers can be installed. Only two were added at this point as one of the bells was a little shy on the paint from the powdercoater and it needed a respray. The transformers also get rubber washers underneath, along with size #8 hardware, including lock washer, washer, nut and screw.

Two of the Edcor transformers in place

The Edcors were wired into place. I've seen a number of members double up the 6.3V taps in order to use other tubes, but for this particular build I only plan on using 6L6s so I won't be performing that mod. The extra 6.3V tap (brown) will be dedicated to the pilot light. The power wiring and front switch was also wired up during this step. Directly after the fuse is a GE Thermistor wired on solder tabs (the little black circle in the middle of the photo below). A thermistor is a resistor which has a resistance that varies depending on temperature. In this case, the NTC thermistor is used for inrush-current limiting. A higher resistance is provided initially which prevents large currents right after turning the amp on. Once it has heated up, the resistance is much lower, allowing higher current flow. 

Transformers and power wired up

UPDATE: After a lengthy delay waiting to get the transformer bells resprayed, I've finally finished up this wonderful little amp. I used a pair of Svetlana 6L6 tubes and a NOS coin-base 6SL7. The Clementine sounds like a champ, surprisingly resolving. For my personal tastes, I like to run it with a subwoofer to get some additional bottom-end extension.

A rear photo of the unit with Cardas binding posts and RCAs

Front photo of the unit

Detail photo of the wood side panel 

Below is the detail of my custom designed and engraved Clementine logo with clipped cornes on a brass plate. This logo was designed in Illustrator (vector) and sent to a trophy maker for engraving.

Clementine custom engraved logo

I hope you enjoyed this build. I highly recommend checking out Shannon Park's offerings at DIYTube and Parks Audio. Also be sure to check out my matching Get Set Go amplifier.

Need a custom audio cable to take your rig's sound to the next level? Contact Zynsonix Audio for smart solutions.

The Fine Print:

Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind.