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April 19, 2012

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. 


  1. This is a great looking build. How did it come out finally? A couple questions. From the last photo it looks like you've added a ground from the board to the chassis, held down via one of the nuts holding the power transformer. Is this recommended? What is the additional white wire coming off the ground side of the speaker binding post? I'm getting ready to build one of these and just want to learn from your experience. Thanks.

  2. Surprisingly, that end bell that was paint shy is still waiting for a new coat. The powdercoater forgot which red he used (he has quite a few), and he finally found it, but when he coated it, the finish bubbled up (presumably from multiple layers) so it had to be stripped and I think it's getting a new coat this week. Laughable because it's probably been sitting over there for 9+ months, but I'm not in any real hurry.

    If you read through the DIYTube forum, and if I recall correctly as it has been quite some time since I touched this project, the amp benefits from grounding the board and negative terminals to the chassis. This is just my recollection though so hit up the boards and verify. Cheers and have fun with it!

  3. Hi
    My intention is to mount the DIYTube Clementine 6L6 Single Ended Tube Amp for personal use. I loved the design.
    I wonder if it is to achieve the source schema.
    Thanks for any information.
    The Ronaldo Silva

  4. It came out Gorgeous, congrats! And thanks for the tip on the additional grounding that benefits this amp!