Decware SE84-DIY build thread.

[Guest David H]

In my quest for better sound, a name that continuously enters the conversation is Decware. After looking at Steve's web page several times over the last year or better, I decided to take a serious look at S.E.T. amplification. The major set back was $$$.... Yes again its the green, not so much that the amps are expensive but the dollars per watt. Recently I checked back with Decware and found to my liking a DIY SE84 amp kit for a measly $300, but I still have some concerns.

Is 2.3 watts per channel enough?

At this price how much quality can I expect?

Will I really hear the EL-84 tube magic?

Is this kit easy enough for a beginner?

Well it time to find out, I ordered the kit and I am ready to build.

Here is a link to the Decware DIY Kits.. http://www.decware.com/newsite/diy.html

[mike stehr]

I think Steve pinched the Decware SE84 circuit from a single-ended 6BQ5/EL-84 General Electric console stereo amplifier.....with some modifications of his own of course.

2.3 watts per channel would be plenty for Klipsch LaScala or Khorn, unless you have a giant sized listening area. Then 2.3 watts won't cut it. I listened nearfield with Lascala using a 71A triode. Something like 800 millivolts per side.......but I had enough power and loudness. I couldn't rattle walls, but that's not what listening to triodes is about......

Hopefully, you get plenty of quality for a single ended 6BQ5 amp.

Single-ended 6BQ5 can sound rather good. I prefer pentode connection. Where there is a screen supply instead of triode strapping a 6BQ5/EL-84.

I dunno if you have heard a directly heated triode such as a 2A3 or 300B in a single ended amplifier, but don't expect a SE 6BQ5 amplifier to pull off the same open euphonic "magic" tone. They can get rather close, however......

Single-ended 6BQ5/EL-84 circuits are perfect for someone starting out DIY with vacuum tubes.

The nice thing about a kit is one can just put it together without much if any troubleshooting. Layout has already been done, the builder just has to follow it. Don't forget to add your touch to the amplifier.....personalization so to speak. You don't want it to look like a typical Decware amp. You want a "GotHover" amp.
[EDIT] Dave Harris amp.

I never could afford a kit amplifier, so I always end up doing full ground up projects. Or reworking a vintage amplifier.And it takes a little time to configure a wiring layout, sockets, transformers, etc....I like doing it, so it isn't a big deal to me.

A Magnavox single-ended 6BQ5/El-84 console stereo amplifier can be found for rather cheap. They are rather nice sounding little amplifiers brought up to snuff with some mods.

I did a breadboard of the "RH84" single ended 6BQ5/EL-84 amplifier circuit. It uses a 12AT7 driver. I was using James 6123HS universal output transformers which was kinda overkill.......but the RH84 circuit I threw together had the closest sound to that of a directly heated single-ended triode. It was real close......With the OPT's used, it was better than the Maggotbox amps with respect to bass.

[Guest David H]

Per the instructions, I verified and separated all of my parts, I started by installing the tube sockets.

Mike, this one I am going to build stock per the instructions, If I absolutely love it, I will install it in a custome chassis, and maybe swap out the caps for ones of my liking.

[Guest David H]

One of my question is answered so far. This amp is so easy to build, I am anticipating 3-4 hours start to finish.

Here is a closeup, as you can see all of the parts are labeled on the board. This is nearly fool proof, Ooops I hope I didn't speak too soon.

[Guest David H]

Now that the resistors are installed, I am installing the caps.

[Guest David H]

Caps instlled, I have to say it kills me to install the $0.25 signal caps in this circuit.

[Guest David H]

This is the shot where I wire the output transformers incorrectly, so much for idiot proof.

[Guest David H]

Decware SE84C DIY completed in just over 3 hours. Almost time for the smoke test.

[Guest David H]

The only Items not included in the base kit is the IEC power cord, tubes and a few jumper wires. Decware does however include the IEC receptacle, and stressees many times in the instruction to strain relief all of the transformer wires to prevent damage.

[Brac]

Nice job, looking foward to your impressions.

[Guest David H]

Great news, the Decware passed the smoke test, voltage measurements are correct, time for a road test.

[Guest David H]

For this amp I used 60's vintage RCA 6BQ5 output tubes an a Bugle driver tube. I let the amp warm up a little, then played a few of my favorite artists, ie Diana Krall, Norah Jones, etc...

[Guest David H]

Preliminary review, Right out of the gate the Decware SE84C-DIY is a nice sounding amplifier, extremely low noise floor for an amp with AC filaments, and is well balanced. I am not going to get to detailed on this prelim, because I have had not had the oportuninty to critically listen. Doing so would be unfair to myself and Decware. I will say this kit is alot of fun to build and even a beginner with soldering experiance can complete this amp in a short amount of time without issue.

I also want to add, I am surprised at how loud 2 watts plays on my Cornscala's.

I will report back in a few days, when I have had a chance to get a little more intimate with this amp.

Comments welcome....Dave Harris

[mike stehr]

The breadboard thing is cool for swapping out parts, tweaking, etc....

I guess if you want to show everything wired up on a piece of wood, here's my breadboard of the RH84 with James OPT's. Sylvania black plate 6BQ5's with a RCA white label 12AT7, Heathkit tube power supply for B+ and heater voltage.

[Guest David H]

Now that is a true DIY scratch build, I think the Decware may have been a little easier. I looked into building my own, but by the time I priced out the parts, I was at or near the price of the Decware.

How did your amp sound? So far I am very pleased with the SE84C-DIY Decware, but I am going to give it a few more days before I write a more thorough review, I am also going to compare to another DIY 84 amp and a 300B. Not exactly apples to apples, but will give me a good comparison.

[The Dude]

Nice work Dave, I think theres another forum member that was wondering if 3.5 watts would be enough for his Cornscalas. It sounds like you were pretty happy with only 2.3, hopefully he stumbles upon this thread especally once youv'e really criticed the amp. Whats the website were you found such a nicely priced little tube amp, do they other stuff.

nick

[Guest David H]

Whats the website were you found such a nicely priced little tube amp, do they other stuff.

www.decware.com Yes, they have an nice list of products, many projects and downloads, enjoy.

[Guest David H]

Today, I spent most of the morning listening to the Decware, and have to admit I am surprised and utimately pleasesd with the overall performance and sound. The only thing I could ask for is a touch more headroom, which I intend to solve by running a pair of these Bi-amped into my Cornscala's. I really feel I need to clarify this statement so it can not be misinterpreted. With 100+db speakers, and a 12x18 room, the average spl at full output is approximately 94db, which is plenty loud, but occasionally I like to irritate my wife, and that is going to require an additional 3 to 6db. Her breaking threshold is 100db

Around 11am Johnny 5 showed up with an Ebay purchased EL-84 powered s.e.t. amp that he wanted to compare to the Decware. Johnny 5 told me did not like the Ebay amp at all, and because this was his first experiance with EL-84 set amplification, he was discouraged about the low powered s.e.t.'s altogether. I played a few passages strong in bass to get him a feel for the Decware, because his major complaint on the DIY Ebay rig was "bass is lacking". After only a few minutes he exclaimed the Decware trashes the Ebay junk I bought. Next I installed Johnny's amp, which by the way must weigh a pound and a half, and proceeded to listen, instantly I could tell his asessment of the amplifier is correct; which led to some testing. I had no intentions of breaking out the osciloscope, but I had to know what was going on with Johnny's amp.

Testing Johnnys DIY Ebay amp... First I hooked up Johnny5's new amp and feed it a 200hz sinewave. Initially the output followed the input nicely, then I dropped the signal to 30hz and the amp trace dropped off the screen, confused I reset the scope got both traces back. What did I do wrong? I thought to myself. Next I increase the frequency to 2khz and watched the ampitude from the amp increase tremendously leading me to believe the amp is non-linear. To verify its not my gear or something I am doing wrong, I hooked up the Decware.

Decware EL-84C-DIY test: Already I am thrilled with the Decwares performance, but to verify what I am hearing an in comparison to the Ebay rig it was necessary to perfom the Identical tests as above. I started with 200hz, once again the traces followed nicely. Next I dropped to 30hz and noticed only a very slight reduction in output, which I expected, what I didnt expect was a near flat sweep from 50hz to 20Khz. I had to go back and verify what I was seeing multiple times, what I found is that the Decware is an amazing low $$$ amplifier that easily competes with or betters my much higher dollar amps in all areas except power output.

My overall opinion of the Decware DIY is this is an incredible amplifier, that deserves all the praise I have given it and more. I am impressed with its quiet operation, and will reccomend this amp to DIY'ers with high efficiency speakers, that listen to music rather than look at it.

Build quality: Steve did a great job obtaining incredilble parts, that won't "break the bank", and work nicely together. The transformers are of adequate size and are quite heavy, nice to know there is some iron in there. The circuit board uses heavy traces, solder masking and, every part is labeled to keep the build as simplistic as possible. There are only a few parts that I would like to swap out, but that is personal preferance, and may not improve performance.

Imaging is impressive, I found myself enjoying instrument placement, and even turned my head to look for a sound, but as soon as I turned it was gone, as I turned my head back the sound returned, it was subtle and pleasant, and I am not sure I had ever noticed it in the past.

Speed and accuracy: When I see this as a defining quality often I roll my eyes. When I refer to speed in an amp, I am referring to bass, and I feel that the bass is accurate, not as bloated as some push-pull amps but quick and full, even pushing a 15 inch woofer the bass sounds very natural.

Well that's it... I like it....what more can I say.

Beware of Ebay's audio jewelry.

[Guest David H]

Both channels - Decware

[Guest David H]

Red is input 0.5v scale yellow is output 5v scale. 1500hz