My New Website

I have a new website dedicated to marketing my tube amps. If you have been following my blog, you might find it interesting. Please check out: www.tubeaudiolab.com

WE91A Monoblocks

Western Electric 91A (WE91A) Monoblocks, construction in progress

Based on the article by Joe Roberts in Sound Practices, summer 1992

Pure Class A , singled ended directly heated triode, 9 wpc

JE Labs 2A3dx II

JE Labs 2A3 Deluxe Single Ended Triode Amplifier

Completed on 7/30/08

3.5 wpc of pure class A DHT SE sound

Tubes: 2x 2A3s, 2x 76s, 2x 6SN7s, and 5U4

JEL 2A3dx

JE Labs 2A3 Deluxe Single Ended Triode Amplifier

Completed on 7/10/08

3.5 wpc of pure class A DHT SE sound

Tubes: 2x 2A3s, 2x 76s, 2x 6SN7s, and 5Z3

Excellent match for those mini back loaded horns

A pure delight for bottleheads...

Those OPTs are trusty Transcendar custom wound in Hollister, CA. They really are fine sounding irons. This is 3rd amp that I built using those irons. It won't be the last for sure.

Completely handwired.

Dynaco ST-70 Type with KT-88s in Triode Mode

ST-35 and VTA SP-6

Dynaclone ST-35 with VTA SP-6 Preamp

Custom order

Completed on 5/31/08

Back Loaded Horn Speakers with Fostex FE-87

Scott LK-48B Restoration Project

Scott LK-48B Restoration Project

17 watts per channel integrated tube amp

4x Telefunken EL-84 (6BQ5/7189)

4x Telefunken 12AX7

2x 6U8A

I often hear fairy tales about how people unexpectedly find something really neat for peanuts in the world of audio. Such tales usually begins with a visit to a local thrift store or estate sale. Well, that sorta happened to me, except I didn't visit no store. I got it on eBay. Got a near mint Scott LK-48B (a kit version of 222C) for $304 by bidding with 30 sec to go in the auction (aka sniping). Yes, like they say on eBay, you don't just buy things - you win things. I was very happy with my purchase and was paying a reasonable price for an amp of such caliber.

When I got the amp I was mostly excited about hooking it up and listening to the amp for the first time. And I was not dissappointed! It sounded soooo good. There was a little glitch with one of 6U8As that failed to light up once in a while and caused one of the channel to go dead. The tube seems to be doing ok now, but I already placed an order for a replacement.

So, here is the fun part - since I had that minor problem with the 6U8A, other tubes caught my attention. I thought it might me a good idea to see if retubing the whole amp was in order. So, I started investigating other ones. To my surprise, all my other tubes, save the good 6U8, looked like they were original Telekunkens! After doing some research on the web, it was confirm that these were indeed genuine Telefunkens. So, basically I had an amp that had tubes that cost twice as much as the amp they are plugged in. Wow, I felt like one of those people on Antique Road Show!

Anyway, I am going to refurbish this beauty up. The chassis will be polished. All pots will be cleaned and lubed. I already placed an order to recap the whole thing, with Auricaps and all. More pictures to follow...

DC Double Darling

Dynaco A-25 Speakers Restoration

WE91 clone Project

WE91 (Western Electric 91) 300B Clone Amp

JJ 300B (4oW heat dissipation) driven by 5693 pentodes

Conservatively around 9 wpc

Completed Feb 2008

So, I have been building loads of SET amps in pursuit of sonic perfection (more like psychological warfare) and I have come to a conclusion that such a thing is unattainable until I built this. I guess what really happen was I built something that I can be content with for a long time to come. I have built several DHT single ended triode amps with big bottles such as 300Bs, 6B4Gs, 2A3s, etc. in various combinations of designs, and I kept finding myelf comparing them not upto par with some of the Darling amps that I built. What was really disappointing was that Darling amps cost only 1/3 of these amps to build!

I did have high hopes in the WE91A. I have been studying this amp for a while on the web, and, after talking with Raymond Koonce who built many of WE91A clones, I decided to embark on building one for myself. It wasn’t an easy decision because parts cost alone was going to be well over a grand. I also wanted to custom paint the chassis, so it was going to be double the work.

I really didn't want to compromise on parts used for this amp. I wanted make sure that this amps will last for a long time to come. Every part used well exceeded in their respective power handling ratings. A good example of this is the Hammond's OPTs that are rated 30W. The amps only puts out 9 wpc. There are in all 9 irons, three of which weigh 35 lbs together. My estimate of the finished amp is around 55 lbs.


I detest tube amps with PCBs, mostly because I like to do things in old school fashion. Everything is point-to-point wired. I tried using as few electrolytics as possible. The only places that I used electrolytics were bypass and filament bias caps. The bypass caps are Black Gates. I used Solens in many places. The coupling caps are Hovlands. The filter caps (large silvers one sticking out on top) are oil filled ASC polypropylene caps. I could have saved a lot of money using alternate parts, but I didn't want to. The power supply section is very robust with a split rail PS with separate chokes.




I was originally going to have the chassis and iron bells powdercoated, but it didn't work out due high cost and lead time. So, I decided to just spray paint the whole thing using automotive paint and clearcoat. It was a lot of work. I put on at least 5 coats of cherry red paint + buffing with rubbing compound in between coats. I then put on about 8 layers of clearcoats with buffing in between coats. I then baked the whole thing at 145'F overnight. I guess it came out alright. I also have to mention that I learnt an important lesson. I neglected to wear a respirator while spraying and really compromised my immune system. I came down with the flu the next day, from which I was bedridden for 3 days. The flu lasted about a full week.

I have never punched or drilled this many holes before. I still marvel at how I fitted all that stuff in a 17x10x3 steel chassis.

Ok, so how did it sound? When I heard it play music for the first time, I said to myself, "Finally, this is what I'm talking about!" I think I have finally found a 300B amp that I could fall in love with. JE Labs 300B was alright, so was GSG 300B hybrid, but they weren't anything that I would get excited about.

The WE91A is so SMOOTH. This amp makes listening so effortless. Even with some of tube amps I have, which I think are decent sounding by anyone's standard, I would get hearing fatigue after a few hours. This one could sing the whole day for I care.
I don't know what it is - 5693 pentode drivers, the design, voodoo- whatever it is it's working for me and I am loving it. Was it worth the flu, money, and time? Absolutely! All that was forgotten when I heard it play my favorite records for the first time.

1626 Darling Single Ended Triode SET Tube Amplifier V

1626 Darling SET Tube Amplifier

0.75 wpc of pure SET sound

5th Darling on sale on eBay

This amp is headed to Singapore. The guy loves the amp. I do hope that he's got a pair of efficient speakers for this to drive. I never get tired of building Darling amps, especially when they bring in good profits to perpetuate my hobby.

JE Labs 300B SET Amps

JE Labs 300B SET Amplifier with James 6123HS OPTs

Custom ordered

Completed on 2/25/08

This was by far the simplest amp that I've wired so far. It helped to have all the big components mounted on top and to have all that space underneath. The only thing that I would have done differently is to have the OPT where the choke is. Steve Chu, my customer, wanted it this way for looks and I just had to make it work. Well, customers are always right. When I first fired the amp up, I noticed that there was clicking noises coming from the bypass cap for 6SN7. Apparently, the voltage handling on the cap was a bit low and was working to its limit. I replaced them with 47uF 160VDC and the clicking went away.

Under the hood with everything mounted on the top plate. Notice the octopus of wires coming out of those holes off of power tranny.

Voila! The finished amps. I thought my Dynaco MKIIIs were big. They are puny compared to those 300B monoblocks!

Yep, all those irons for glorious 9 watts of SET audio.

These monoblocks weigh at least 40 lbs each.

Size comparison of James 6137HS iron to 6113HS. The 6137HSs are SE 30W 7K primary and 4, 8, 16 ohms secondary taps. I am putting 8 ohms loads to 16 ohms taps to lower the primary Z to 3.5 k for 300Bs. It's all about ratio when it comes to trannies.

How does it sound? I am very happy with these amps. They really groove to the music when listening to rock or pop music. Great textural rendition and rhythmic integrity when listening to complex ensemble. 9 wpc is plenty for my listening level and the efficiency of my speakers, but it's still just 9 watts. They do seem struggle a tiny bit when I try to push the full power of orchestra through them. All in all, their dynamic performance is amazing for most music I have CDs, mp3, and records for.

Will I build these for myself? Probably not, mostly because of its size and the cost of construction. I think the same caliber of sound can be achieved using other designs in stereo at 3/4 of cost or less.