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. 

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. 

 

The Millett DCPP Engineers Amplifier

Another great project from the man himself, Pete Millett. The Engineer's Amplifier is a distortion canceling push-pull amplifier that makes use of low-cost TV tubes, namely four 6JM6s and 6CB6s. If you prefer the top cap look, you can substitute 6JN6s for the 6JM6s. The amplifier puts out about 18 watts in stock configuration, or well over a hundred with some tweaking (take a look at TubeLab posts especially). As seems to be the recent tradition from Pete, the board is large and bright red, and makes use of a compliment of Edcor transformers. The audio path is pure tube except for the CCS in the LTP tail, a few tube purists may take issue with that but they'd be missing out on a great amp ;)

There they are! Fairchild FQPF8N60C

Some nice concessions to us vintage parts lovers are the lovely green Koa Speers carbon film and traditional carbon comp resistors, the latter being used as grid stoppers. There's also some good old silver mica caps in there. I decided that I wanted this build to be unique, and had some interesting ideas in mind, including a nice Zebrawood wood base with an illuminated slot for the logo and a copper / antique copper powdercoat scheme.

Board top with ceramic tube sockets

Board bottom with resistors populated

I initially build this amp with Russian paper in oil caps:

Russian PIO

But eventually settled on AmpOhm aluminum paper in Oil.

AmpOhm aluminum foil paper in oil capacitors

Here's some final photos of the build:

Orangey Red LCDs

Cardas copper binding posts and Vampire RCAs

The illuminated logo was achieved by using a piece of perforated powdercoated metal as the base, then fastening the "Millett" brass logo I designed on the front. Lighting the logo from behind is a small circuit featuring 16 diffused orange LEDs that runs at 6.3V off the heater. The nice top plate with cool little perforations around the MOSFETs was made by Bob Collins (DIYAudio member PPP6l6gc) for a very reasonable price.

Some other fun little upgrades from the stock build were:

• Cardas Copper Binding Posts
• Vampire RCAs
• Kimber and Oyaide Wiring
• AmpOhm Paper in Oil Aluminum Capacitors

The sound is very detailed and engaging. Quite the opposite from the lush Dynaco ST70. Another recommended build from Pete Millett.


Wondering where I got all my parts for this build? Check out a list of my favorite online vendors here.

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.