IF THE 1ST WATT SUCKS, WHY CONTINUE?

Most people would assume that a 2-watt single-ended tube amplifier wouldn’t have what it takes to get out of its way, let alone control a loudspeaker to a dynamic conclusion. They would say, “It couldn’t possibly have any real bass, but we hear the midrange is to die for.”

Many would assume that the only way to use a lower-powered 2-watt amp is with huge, nasty-sounding horn speakers.

Despite popular belief, you don’t need large horn speakers to receive stunning sound quality from a good SET amplifier. Many alternative speakers (that are high-efficiency and easy to drive) can be purchased as excellent alternatives for this amplifier style. However, my ideal speaker for this amplifier is the Charney Audio Maestro Extreme with Voxativ A2.6 drivers @ 101db. Yes, it would be best to have high-efficiency speakers for this amp, and they are pretty much required., But honestly, that can be accomplished with cabinets that don’t need two guys to move.

WHAT ARE THE ADVANTAGES OF A 2W 45-TUBE AMP AND A PAIR OF HIGH-EFFICIENCY SPEAKERS?

1. The first thing that I would cover is that after buying, selling, and building almost every amplifier design known to man and while using nearly every type of speaker design, I’ve concluded that tube amps provide an emotional connection to music that is better than any other alternative and this is the direction for my final creations. All of your musical presentation is contained within the 1st watt, and that 1st watt must be beautiful and not just technically correct.

2. If you use high-efficiency speakers (@100db or higher), you only need another watt to propel that beautiful sound quality into your listening space. If you use more watts (than the 2 watts that a 45 tube provides) with a lower efficiency speaker design (but still higher than average), you’ll compromise your final sound quality but possibly gain some other features. The sound quality improvement is the most important, in my opinion, and the different things you might achieve with a more powerful amplifier and less efficient speakers aren’t worth it. The emotional connection to music becomes lost even though other aspects of music reproduction improve. I’ve tried the best market designs and built my own, so I speak from direct experience. I’ve been attempting and investing my time and money in this lengthy search. I think a two-power tube triode DHT-type amp provides the best sound quality. Yes, you can improve things with more power (such as using parallel tubes in an SE design), but this still holds compromises. The least compromised, best sound quality comes from a two-power tube amp (either 45, 2A3, or 300B). Even with those three designs, there are still plenty of variables to deal with to achieve the sound quality you might prefer.

The best sound quality (based on my own experience) is obtained with a 45-tube amp (2 watts) and a pair of high-efficiency speakers that are at least 100 efficient. That is an ideal and should be what most people would enjoy, and it is what I now use myself.

WHY THE 45 TUBE INSTEAD OF THE 2A3 or 300B?

Again, through the experience of building high-end amps that use all three stellar DHT tubes, the 45 is the absolute best! I’ve built and purchased other builds from manufacturers for all three tubes. The 45 tube is the absolute “best” for me, and I know what live music sounds like. I’m a former professional jazz piano player and have played on stage with numerous other musicians in various venues. The 45 tube provides the closest sound quality I’ve ever heard, reproducing recorded music of these performances. Here’s what Sophia Electric has to share about this:

“The 45 would have been forgotten for its modest power output. However, one outstanding strength has made audiophiles rediscover it decades later. The sound from the 45 tubes is simply pure, seductive, and even magical! Anything good that can be said about the 300B tube, the 45 can do better, with only one limitation of 2W output, versus 3.5-4W from 2A3 and 8W from a single-ended 300B.”

The 45-tube amp I built is an absolute success, and I’m happy with its sound quality. Finding the right matching high-efficiency speakers is the only thing that becomes difficult when using a good 45 amp. Brian Charney has a line of speakers, and I would begin with his Maestro Extreme cabinets and a Voxativ A2.6 driver as a minimum recommendation for this system. If you purchase this speaker, you will not be sorry. It’s one of the best systems I’ve ever heard – second to none.

However, I’m now back to listening, building, and finding that elusive 300B amplifier that will exceed or at least equal the sound quality of the 45 tubes (but have a bit more body and the beauty that comes with the 45 amp). I’m working with several circuit designs and will look for the best one for the system I put together. Stay tuned! Having a closer sound to 8w/ch allows more speaker choices to play more genres of music in all rooms. 2 w/ch needs speakers that are 104db efficient and not around 100db to sound the best, and this is the main reason I’m now back to working with the 300B amp. I won’t quit until that “magical” power amplifier that uses the 300B tube appears.

My Selling Price For This Amp Is $12,000

This is not an inexpensive amplifier to build. It has all film capacitors and a hybrid build design. I use custom-printed circuit boards that I designed and built because the wire gauge of my resistors and capacitors is too large to solder directly (both ends) to my Yamamoto tube sockets.

I’ve spared no cost to build this amp. It’s the third and final version, which is extremely special. All future amps will be identical, but finding above-average parts is now a problem. It seems that the world is getting less quality-conscious as time goes on.

I’ve used all the expensive Teflon Yamamoto tube sockets that I purchased directly from Yamamoto in Japan. Those are still available as I write this.

I’ve used an expensive Hashimoto PT-160 power transformer and a pair of Hashimoto H-20-7U potted output transformers. The selection of output transformers is the most important thing to include in an amplifier. These are overkill in size, but their frequency range is excellent, and the sound quality is even better than the last version of this amp I built using vintage Tamura transformers. This particular amp is the best without comparison!

All resistors are expensive Audinote 2W Niobium silver non-magnetic except for the pair of Audionote 2W Tantalum silver non-magnetic used between the input jacks and pin1 on the 6SN7 tube socket. 

Mundorf makes all of the capacitors, including the three tube caps in the power supply, which are film caps. I’ve used a pair of Silver In Oil Mundorf supreme coupling caps and sized these capacitors to provide the best sound quality.

The Lundahl 10H choke, LL1638, is used between the 1st and 2nd capacitors in the power supply and is recommended for use with the EML 45 tubes, which I also recommend for use in this amp.

I set the voltage on the 45 tubes to slightly more than 260 volts. The max for a pair of 45 tubes is 275 volts, and the max for a pair of EML 45 tubes is 300 volts. I still need to take a photo of this new 30W resistor (again, overkill, but it will operate warm and not hot at this size). I used a large 25W rheostat to find the best-sounding resistor value and then ordered that resistor value. I tried all the voltages between 250V and 300V before settling on the installed resistor values. The 6SN7 tubes operate much less than their maximum and will last longer.

This is the most beautiful amp I’ve ever heard, and combined with a pair of high-efficiency speakers, it’s as good as you’ll get. Plus, how I’ve built this one will provide decades of use without the need to recap any electrolytic capacitors you will find in other amps. Every solder joint was made using a 10X headband magnifier, and each joint has been carefully cleaned so there is little to no solder flux residue.

The input plus and minus wires use solid silver 24 gauge wire provided by the low-capacitance Venhaus wire I installed.

The dual mono pots are TKD 100K pots, and after experiencing dual mono pots in my two prior amps, I will not go back to using a stereo pot.

I highly recommend purchasing a Khozmo build passive preamp with a remote control unit if you want a remote control. If you’re going to use an active preamp instead, no problem. Both will work well. However, no input capacitor is installed in this amp between the RCA jack and the input wire. This results in a much cleaner sound quality, plus no need to choose an expensive capacitor that doesn’t affect sound quality. If your preamp is designed correctly, you will not have a problem. If there is a slight problem, you might need to have input capacitors installed (one pair), and that’s easy. However, it is best not to use them unless you absolutely must.

The rest of the wire in this amp is mostly 18 gauge Venhaus copper and silver and some 21 gauge Venhaus (for connecting both 6SN7 tubes).

All tube sockets are mounted on hanging plates isolated from the top plate with 1/4” rubber dampers. This arrangement reduces tube vibration from the amp and prevents it from easily transferring back into the chassis.

The RCA jacks are my favorite (FP-901 rhodium-plated made by Furutech). The binding posts are KRYO ITE posts (again, now my favorite). The IEC module is Furutech FI-03 rhodium. Everything has been chosen after many decades of building and listening to amps that I build. This one has all of the parts I’ve found to be the best-sounding and provide the longevity I planned for this amp.

This amp should last for many decades of use. The top plate is chrome-plated 1/8” aircraft aluminum, and the sides and bottom plates are all extruded 1/8”. It takes me about three months to build this amp using CNC-based software. The capacitor mounting plates are custom Front Panel Express created, and the printed circuit boards are blackboards made for me (my design) by OSH Park in California. The power transformer uses 16 gauge Notch wire to connect to the 120V input line.

The hum pot is a vintage Russian pot that is substantially overbuilt. Something like this could easily cost $600 if it were a new part. Fortunately, the cost of this pot is reasonable since I purchased it new, but it’s an old stock part. The large 30W Ohmite resistor in the attached photo adjusts the voltage in the hum pot. The 2nd 30W Ohmite resistor not in this photo (but now installed) is to drop the voltage from the rectifier tube to slightly over 260 volts.

This amplifier is the best I can create and results from decades of building and listening to systems I’ve built, purchased, and made by others.

Kevin at glowinthedarkaudio.com reviewed my prior 45-tube amp. He loves this amp, and you can read his review on his website. However, this next 45 amp is even better, and I would say it is about as fine a 45-tube amp as you will ever find.