Douk Audio Class A & AB Pure Tube Audio Matching Power Amps & Preamps

 October 1, 2025

#522

Gentle reader,

Since I came across a Chinese designed and made all-tube power amplifier at a bargain price on eBay, which I wrote about here: The Robb Collections: World Premiere Review  of Douk Audio's Exciting new Class A DJ587 Tube Stereo Power Amplifier! I have continued to be Douk-curious. I updated that article with what I thought was THE matching preamplifier. Turns out, I only knew part of the story.

All Douk Audio images courtesy of Douk Audio.

Well, it turns out there are at least two different ones, both using the same chassis, but with varying numbers and types of tubes. The DJ198 preamplifier is pictured above.

"This!" I'm channeling Doug DeMuro again, above is their DJ417 preamplifier. Note the numbers of and configuration differences. I had come across a DJ918, but it turns out that was a typo as it is "Identical!"* to the DJ198. *remember: My Cousin Vinny

This is identical to the DJ587 power amp which I reviewed and am thoroughly in love with. It is advertised as a "Class A" power amplifier. 

And this, is a DJ511. Note the differences between the two of them. The DJ511 is a "Class AB" "Push-Pull" power amplifier.

This is the rear of the DJ198 preamplifier. 

And this is the rear of the DJ417 preamplifier.

These are the four tubes which the DJ198 preamplifier uses.

These are the six tubes used in the DJ417 preamplifier.

This is what is inside the factory assembled DJ198 preamplifier.

And this is the insides of the factory assembled DJ417 preamplifier.

The much simpler (looking) Do-It-Yourself version of the DJ198 preamplifier.

And this is the insides of the DIY DJ417 preamplifier.

I am 69 years old and had my first job as a fledgling auto mechanic in 1973. My father had a Hallicrafters multi-band tube radio when we were growing up, just like this one. IT was my first experience with tube audio equipment. I was allowed to take it to work so that I had music. IT received AM only, WGOE was my rock station. What I knew about tubes then: It takes a while to "warm up" to make sound. And, do not stick your fingers or anything else inside the back of the radio. That was it.

This was Nancy's father's actual Hallicrafters multi-band tube radio. It still worked when we were dating in the early 1990's. Nancy inherited it. I have not tried to see if it still works. It might.

This is a Hallicrafters Civic Patrol radio I found in an antiques store and bought. It does nothing but buzz. Maybe the frequencies are no longer used. I do not know.

This dangerous and I-do-not-even-want-to-try-and-see-if-it-works, Philco radio I bought for five bucks, also from an antiques store.

These are is it's guts after I cleaned them up and put them back inside.

This is an identical, but slightly older Philco I bought via eBay for ten bucks. It is in surprisingly good condition and has the proper factory knobs.

When it arrived, the back cover had been shoved in a bit during it's trip to our house. I removed it to fix the cover. I found everything clean and shiny inside, much to my delight. As you can see by the tube's glow, it works. It's AM only, but it's from 1937 and it WORKS!

What I have learned about tubes since then is: Tubes operate at high voltages, thus the three transformers verses one, the AC power transformer, in solid state equipment.

This is the back of the DJ511 power amplifier. Note a single input.

This is the back, identical to my DJ587, power amplifier with two swtiched inputs.

The insides of the factory assembled DJ511 power amplifier.

This is the eBay photo of a DJ587 which was in the eBay ad for the one I bought. I have not taken the bottom cover off to see what may be much different (based upon every other unit in the series) that what this photo shows. Perhaps more like the other factory assembled units shown above.

Note: All of these new product images were made by Douk Audio employees in China. I secured all of them from their eBay product ads on eBay. The vintage equipment (minus the first Hallicrafters photo) were made by me.

Now, that you have the model numbers of the two preamplifiers and two power amplifiers they have produced so far, with this chassis. I look forward to reading your comments regarding the differences between the two sets of fraternal twins. For instance, which of the two designs is better.

One last thing, if you are a tube aficionado, what benefits could one expect by using NOS tubes or Soviet ones compared to the modern day Chinese made ones? 

Thanks for taking the time to read this, the second chapter, of my new interest in tube driven stereo equipment. Feel free to leave a comment below, or via Facebook.

I write two more blogs, but have not updated either in a while: Pictures of Nancy. The Love of My Life. and: People Say I'm Special. But I Don't Know Why

Scott Robb

October 1, 2025

#522