Aum Acoustics
Integrated 45 Tube Amplifier

“The Aum Acoustics 45 tube integrated amplifier equipped with the Emissions Lags (EML) 45 mesh plate triodes, the Grant Fidelity Treasure 6SN7SE triodes, and the 6AX5GT rectifier  provides the finest combination of musicality and audiophile-style sonics that I’ve ever heard.”

My Custom Integrated 45 Tube Amplifier

Thank you Allan Eaton! I purchased your upgraded 45 tube amp and loved it. Your circuit design and the vintage transformers that you use make all the difference in the world and I knew I could use your proven circuit design and your same vintage transformers and vastly improve your already beautiful sound quality. After contacting you and building a relationship, I designed one of my custom cnc chassis for your own personal 45 tube amp along with my new version. My chassis is 1″ wider to accommodate the large Mundorf gold/silver/oil capacitors that I used instead of inexpensive electrolytic capacitors.  After that purchase, I then added two pair of V-Cap CuTF capacitors and Audionote 2W Niobium silver and 2W Tantalum silver resistors plus a host of other upgrades. 

You sent me a complete transformer set (all Tamura vintage iron) to build this amp and I substantially upgraded your circuit design so that none of the parts are even close to the same. The price of these parts is many times what you’ve used and because of the way I built this amp from years of my own experience, I accomplished the goal that I sensed was sitting there – untapped. I built an incredible sounding amplifier that is both beautiful and archival. The sound quality is stunning and breathtakingly beautiful.  Now that its built and playing sweet music in my studio I thank you for your friendship and for allowing me to build this new amp using your Tamura iron and your circuit design.

I ordered a custom pair of Coherent Audio speakers and after 6 months of waiting for them, I gave up and moved on and am glad I did. I cancelled that order and am through with that company. Instead, I purchased a pair of Charney Maestro single driver speakers with Voxativ A2.6 drivers that are 101db efficient and are a perfect match for this new amplifier.

During my prior exposure to using the 300B tube and 2A3 tube, I’ve given up using both (particularly the 300B tube). I just don’t like the 300B anymore and the 2A3 is too “boring”. I found out that the 300B has too much “push or tension” in the midrange. Can this be corrected? Somewhat but it would take a really stiff power supply and probably would cost closer to $20,000 to tame this tube properly. That’s crazy and I have no interest in doing that.

Years ago, I built an incredible 2A3 amplifier. I really liked it but didn’t have the right speakers and ended up selling it. The 2A3 tube amp I built would be a better solution than when using a 300B tube. However, without really good high efficiency speakers (since the 2A3 reduces power from the 8 w/ch of a 300B amp to 3.5 w/ch), neither amp design worked well for me. The 2A3 tube didn’t wound right at the time so I sold the amplifier. I didn’t find the right speakers back then even though I should have kept that amp but didn’t. I’m now glad that I sold it. I almost built it again.This new amp, however, sounds much much better!

My goal was to purchase a pair of really high efficiency speakers so I could use a superb low powered SET tube amp but I hadn’t yet found those speakers. And instead, chased many other designs where I basically wasted a huge amount of money. If I had come across the amplifier I just built and had the speakers I recently purchased, I never would have used another system. That would have been my “desert island” setup.

Cancelling the Coherent Audio speaker order was the best thing that ever happened to me. Those speakers would have been 97db in efficiency (a good move to gain better efficiency) but also used the 12″ Radian coax speakers that were good but not good enough. My friend, Frank Ng at Triode Labs in Canada, didn’t like the Coherent speakers with any of his amps. His favorite speaker design was a good horn and there were many to choose from but the good ones typically were way too large and heavy for me. I gave Coherent 6 months to build the speakers that I ordered and in the end, I gave up. There’s a lot more behind this decision but I won’t share that with you since my cancelling this order tells you something and that’s all that you need to know.

I immediately called Brian Charney after cancelling that order. I originally spoke with him about his speakers prior to placing my order with Coherent Audio. However, Brian doesn’t work with distributors or dealers and doesn’t offer a margin on his speakers. That’s the only reason I originally didn’t have him build a pair of speakers for me during that original conversation. I went with Coherent Audio since I was to receive a 40% margin so I could sell those speakers as an audio dealer.

So after cancelling the Coherent Audio order, I called Brian Charney and asked him about the Maestro Extreme speakers that he was building. I liked their appearance and the weight and size was as large as I wanted to go. Partime Audiophile had just reviewed the normal Maestro with both the Voxativ A1.6 and A2.6 full range drivers. The reviewer found that the A2.6 added the body that was missing from the A1.6 Voxativ speakers and that’s what he recommended. After that review, he found that the larger Maestro Extreme cabinets that Brian sent him (prototypes at the time) made all of the difference in the world and he purchased the Maestro Extreme speakers to use as his review speakers. Normally, he would have sent the speakers back and moved on. These impressed him so much that he spent his own money to make this purchase and to keep them – permanently.

After learning that, I purchased a brand new pair of baltic birch unfinished Maestro Extreme speakers from Brian with the Voxativ A2.6 full range drivers. I spent a day sanding those and then applied eight coats of wipe on poly and now the speakers are done and look great. These speakers are unbelieveably good and do not require the addition of a subwoofer to get adequate bass. Brian’s low end frequency response of 38Hz is accurate (in my room) and these speakers are 101db efficient. They are perfect speakers to use with my new custom w w/ch 45 tube amp. In fact, they are the missing speakers I’ve been searching for a very long time. These are “end game” speakers and I’m very pleased with them (particularly when combined with my 45 amp).

I had imported 4 pair of Rethm speakers (as a distributor) in the past and never liked them. Those too were expensive and had full range speakers with separate bass speakers and a bass speaker amp built into each cabinet. They just didn’t have the sound quality I was looking for, were too thin sounding, and only about 40% of my music sounded really good using them with my custom 2A3 amp. After that experience, I built two more full range speakers with different drivers and the same result – thin and no bass. I quit and moved on to 2 way systems that were much lower in efficiency.

I’ve been building audio components for many decades and finally, in 2021, I built my first 300B amplifier. I’ve heard this amp type used in other systems but didn’t like the lack of treble and loose bass. Very few 300B amps are designed well to sound their best compared to other stellar amps (like the 2A3 and 45 tube amps). Previously I had built a stellar 2A3 amp and always liked the 2A3 that I used better than the 300B amps I’ve heard. However, there is something about the 300B tube that seems to provide the most beautiful midrange ever heard even though its unnatural. If you also want a good linear presentation and correct sound quality that comes as close to live music and also want tight bass and extended treble, then you need to spend some serious money on the amp and the related tubes that I’m now using. The 300B amp just isn’t worth using (in my opinion). From my experience now after building 2 300B amps and owning a 3rd one made by Triode Labs in Canada, I’m done with 300B amps. I just don’t like that tube enough to use it anymore. To get the amp to sound good costs way too much money and the complexity involved is insane.

If you aren’t using stellar transformers (particularly output transformers) like those made by Hashimoto (in Japan) then you’re missing out and probably should consider using a different tube type amplifier. Solid state? I can’t go there any more. Even though I’m a detail freak and have worked with many Class A solid state amps, I find that a tube amplifier provides a degree of emotional connection that I can’t obtain with any solid state amp. If I use solid state, then I need to also use my own custom built tube preamplifier (with Tortuga LDR volume control) but that detracts from the sound quality even though it initially sounds like the best solution. Simplicity is the key to obtaining the absolute best musical sound quality. Finding that solution, however, is like looking for a “needle in a haystack”.

What caused me to try the 300B tube power amp instead of my Pass solid state power amp (with my custom tube buffer) was my construction of several Elekit 300B 8600S DIY kits. This Elekit amp kit was reviewed positively so many times that I had to join the rest of the builders to find out what was going on. Eventually the ruckus was too much and I joined the fray. I love building amps but typically build my own from scratch. This time around, I purchased a retail priced kit that was easy to put together and I was surprised at how good it sounded (even though it wasn’t what I ultimately wanted for myself). It still had too much push in the midrange (a level of tension) that I didn’t want and didn’t use a rectifier tube and choke in its design. It had a solid state rectification design and is probably why some of the other reviewers enjoyed it. It sounded better than most 300B amps but still didn’t sound anywhere near the quality of a $20K Border Patrol 300B amp with a stiff power supply.

I heard a beautiful tube amplifier sound quality once I had my first Elekit 8600S built with Lundahl transformers, V-Cap CuF coupling caps, Takman resistor upgrades, and TKD pot upgrade. However, this amp sounded more like a 2A3 amp rather than a 300B. That was partly due to the fact that the 8600S uses solid state rectification with no choke rather than the typical tube rectifier. Even though the voicing was good, it wasn’t good enough (not emotionally attractive enough) so I kept looking at other 300B designs but was using the 300B tube as the underlying basis for this search.

I ended up purchasing a pair of Takatsuki 300B tubes to elevate my sound quality beyond the Cossar WE300B tubes that I initially used. Yes! Those were excellent but they sure were expensive and the amp still had an unnatural midrange and honestly way too much treble that revealed the distortion underneath. You needed a “dark sounding” speaker system to really use this tube and that’s not what I had at the time. I was using a pair of DIY GR-Research NX Studio monitors that I had just built with a pair of expensive subwoofers as stands. After making this purchase and going through the aggravation of building these speakers I moved on and continued my search.

One of my favoite amplifier manufacturers is Finale/Triode amps located in Canada. I’ve been a dealer for them in the past and decided to purchase their Triode 300B EVO21 tube amplifier to find out if it could obtain the sound quality I’ve been looking for during my long adventure in audio with their circuit design. It used 300B tubes (I already owned the Cossar and the Takatsuki 300B tubes) and it had a tube rectifier and choke. So potentially, the emotional connection would be there and I was very interested.

To summarize: Yes! This amplifier had “that” beautiful yet detailed emotional sound quality that I desired. But it wasn’t easy to create that sound quality and I had to use a large number of exotic 9 pin tubes from my collection to get it to sound right. In the end . . . it still didn’t sound right. I listened for awhile and then decided to sell it (and move on again). The 300B tube even in that amp just didn’t have the sound quality I was searching for and I didn’t like the printed circuit board design build that Triode uses.

At around $9K in price for a Triode Labs 300B built with Hashimoto iron (some of my favorites) this solution just wasn’t it. I no longer have an interest in any 300B amp and am not going to pay $20K for a Border Patrol version just to hear it. That’s insane. I’ve now given up on using the 300B tube.

What’s the catch here? Unfortunately, to obtain the best sound quality using a 300B amp, you need to spend some serious money. The 300B amp that I last used costs $9K (without expensive tubes). The best sounding pair of Takatsuki 300B tubes retail at $2,500 a pair and of course, the other smaller tubes and rectifier tube are expensive too. Once this expenditure is made, the sound quality becomes good (if you know how to pick the right tube combination and own enough rare tubes to come up with a decent solution). And, for a 300B tube amp, this isn’t expensive compared to the other few better alternatives. But . . . again, the sound quality is not right and I couldn’t listen to Triode’s 300B amp beyond a short period of time. I sold it. To get this amp to even sound right required a really expensive array of tubes and tubes are like light bulbs. They only last for a specific period of time and then you need to purchase them again to keep going (if you can even find them). I wasn’t interested in throwing away that much money over and over again and while working with vanishing tubes.

Another concern that I had is that speakers need to be high efficiency types for a 300B amp (around 95db or higher) and that is somewhat limiting but not impossible to come up with a good solution at different budget levels. I guess that’s the reason many choose that tube type since there are more speakers that work well with it. However, most of those people don’t build amps and are not accomplished musicians who know what real music should sound like so they don’t have a clue that there actually is a better solution at a reasonable price (particularly when you consider re-tubing over time.

My Custom 45 Integrated Tube Amplifier

“The Aum Acoustics 45 tube integrated amplifier equipped with the Emissions Lags (EML) 45 mesh plate triodes, the Grant Fidelity Treasure 6SN7SE triodes, and the 6AX5GT rectifier  provides the finest combination of musicality and audiophile-style sonics that I’ve ever heard.”

I’m done with the 300B tube as well as the 2A3 tube. Neither one led me to audio nirvana as I had planned. My expensive Triode Labs 300B EVO is now sold and has been replaced by my custom Aum Acoustics 45 integrated tube amp. I’m very pleased with that decision!

My Triode Labs EVO21 300B That Is Now Sold!
My 2A3 Amplifier Is Also Now Sold - My 45 Amp Is Better