DIYTUBE 6B4G Get*Set*Go GSG SET amp

GET*SET*GO Single Ended Triode Amp

2x 6B4G with 6SL7 Driver, 6AX5-GT Rectified

3 wpc of pre SET power

Completed on 10/17/07

My friend Steve Chu whom I made the original GSG SET with 6B4G for wanted have the 300B mod done on his. So here you have it. Those big bottles are JJ 300Bs. I honestly can't tell if they are any better than EH 300Bs that cost 40% less. They look pretty imposing though. The sound got cleaned up quite a bit. I really do like the solid state rectifier with the amp. I personally prefer sharper sound. I tend to get a warmer sound and less definition. Some folks like that. It's merely a matter what you like the best.

Shure M-65 Clone Phono Record Tube Preamp Preamplifier

Shure M-65 Clone Phono Preamp

RIAA equalization using a pair of 12AX7

Powered with a pair of filament transformers

Completed on 9/26/07

Inspired by the fact that my new Adcom GTP-600 preamp didn't have a phono stage...


Yep, I could have used a bigger chassis, but I worked with what I had on hand. I Can't believe I fit all the parts in a box this small. It looks cool messy like this with an open top, so the cover's off. It sounds pretty natural and brings outs the vintage vinyl sound. The only modifications that I made on the original M-65 schematic is rectification on the filament power supply and the increase in capacitance for the PS. A cool little project under 60 bucks...(I did use parts pulled from my other guitar amp that I gave up on).

Dynaco Mark III MKIII Monoblocks - Refurbished

Vintage Dynaco Mark III (MKIII) Monoblocks

60 watts per block

1x 6AN8 drives 2x KT88 per block

Restored and converted using a pair of MKIIs

completed on 9/13/07

6L6GC SET "Simpleton" amp

"Simpleton" 6L6GC Single Ended Triode

1.5 watt per block

1x 6SL7 drives 2x 6L6GC

Designed by me

Sold on eBay!

Built on 9/2/07

I happened to have a aluminum base painted in cashmere beige for another project the never got finished. It was a perfect fit for the top plate. The 6L6GCs are brand new Svetlanas that I orignally bought for my ST-70, but I wasn't impressed with how it sounded with those tubes. So, I am using a matched pair for this amp and the other for a guitar amp. The 6SL7 is nearly NOS Tung-Sol. They all look neat with the brown base. The rectifier tube (6X5) is Sylvania.


This amp sounds pretty good. I was a bit concerned with the 7.5k primary on those Valve Juinor OPTs, but multiple secondaries allowed for experimentation and I liked 4 ohms tap to 8 ohms load with my speakers the best. The bias is very similar to 6V6 tubes, so I tried those on the amp and it sounded great with a plenty of SET power. All in all, this project was a success. I built it to sale on eBay, I like it enough that I might just keep it...

13EM7/15EA7 (6EM7) "Miniblok" SET amp

"Miniblok" 13EM7/15EA7 (6EM7) Single Ended Triode

1 watt per block

15EA7 - Dual Triode (Driver/Amp) Silicon Rectifiers

Sold on eBay

Inspired by late Fred Nachbaur

Built on metal-on-wood chassis.

Finished product! 13EM7s are dual triodes that have one section capable of high gain but low power, thus ideal for a preamp stage, and the other capable of low voltage gain and high current, thus ideal for a power stage.

Under the hood. Again, like the 6080 SET, it's a bit crammed, but the layout is well thought of before hand and minimal wiring is employed. The power trannies are two 12.6 VAC filament transformers in parallel, powering the two 12.5 V 450 mA filaments and a reverse connected 12.6 VAC > 240 VAC transformer for the plate voltage. There is a bit of hum (hardly audible), which could be due to AC filament supply. Fred used -3o VDC for fixed grid bias. The man was genius. He knew how to use cheap (including tubes) parts to make amazing sound tube gears. The schematic for "Miniblok" is available here.

These amps sound real nice. Don't let 1 wps fool anyone - these probably are one of loudest amps I have heard save the ST-70. The sound is open and spacious with strong mids and a plenty of tight bass. I have a tube audio buddy who built one of these in stereo and think that it sounds better than his 300B that cost him a fortune to build! 13EM7s do make some nice SETs. It would be interesting to hear a Push Pull version.

6AS7 6080 Lilliput Single Ended Triode SET Tube Amp

"Lilliput" 6AS7/6080 Single Ended Triode

RCA 6SL7GT Driver - 6AS7/6080 outputs
Rectified with 6AX5GT

Completed on June 2007


Built on compact 8x5x2 Hammond chassis

6AS7s can be substituted with 6080s. They are twin triodes with incredibly low plate resistance, often used in OTL designs or head phone amps.

Under the hood . A bit crammed, but got everything in there including those tiny output trannies that fit comfortably in one hand. In spite of their small size, they pump out good volume with efficient speakers.

The amp was originally designed to be driven by a 6SN7, but I had some trouble biasing the tube with parts that I had on hand. So, the 6SL7 came into rescue and it worked out great. This project gave me an idea that I might want to experiment with later - run 6as7 in parallel per channel and hook up bigger OPT with lower primary impedance (1.25 k to 8 ohms). That ought to yield around 7 wpc. Hmmm...

DIYTUBE Dynaco ST-70 - Refurbished

Vintage Dynaco ST-70 Modified with DIYTUBE ST-70 Driver Board

35 wpc in stereo and 70 w in mono
Completed in June 2007

The ST-70 is an amp that no tube aubiohobbyists should live without. This was an eBay find that was in pretty good working + cosmetic condition. However, I wan't terribly impressed with its sonic characteristics, particularly it's tubby bass and lingering muddiness in mids+highs. So, it was was time for a makeover.

...and after!!!!

The chassis was completely gutted and cleaned first with Fast Orange to get rid of years of organic deposits. The chassis was then polished several times with Turtle Wax's chrome polish, followed by Blue Magic metal polish, all of which are cheaply avaiable at local discount autopart stores. All tube sockets were replaced with ceramic octals.

and after...

Shannon Park's DIYTUBE ST-70 driver boards are a standard upgrade of the 7199 boards. The tube complement is 1x 12ax7 and 2x 12au7. The design is pretty much a time tested modified Mullard design dating back 50 years. The board allows individual biasing of output tubes for push pull perfection.

Under the hood...everthying was rewired and neated tucked away.

The only thing that's left to be done on the amp is to retube. 3 Svetlana and 1 Mullard EL34s (Russian productions) are on the power duty for now, and I would like to experiment with 6L6GCs or KT77s. All in all, the restoration was a great success wiht much improved sonics. It pumps out some serious wattages of pure listening enjoyment - deep and accurate bass and very forward mids. Great sounding amp!