Your journey with lower-watt tube amps -- Can a kit be good enough?

Thanks for the Dynaco ST-70 et al. suggestions. Since I am already running a Quicksilver Mono 60 with KT-77 tubes, I'm not sure this amp is really going to sound all that different. If I stick with the vacation analogy, I want to emphasize that I want to go somewhere really different and not have a "staycation."

I've had really good experience & sound with Mellow Tone Kits. Easy builds & their build instructions are posted on YouTube videos. They also give you all the specs & measurements for their equipment. Now I've only built 2 of their preamps..one in full kit form & the other just using the PCB boards they sell separately for a good price..though they did go up in price this year. Their boards are very versatile so you don't have to stick to the schematic they share. 

I've listened to their GU50 8watt monoblocks recently & was very impressed.. especially for 8watts. I thought it sounded great.  It's like $2k for the full kit though. I will add that I really like these guys at Mellow Tone/ValvesnMore. Super cool. 

I've built the original ST-70 & find it ok.. good amp for the money. When you part them out all new & spend under $1k it's just a good deal for a tube amp. A buddy has the Tubes4Hifi 12au7 ST-70 & it seems solid & an upgrade to the original..just a little different. I built their most recent SP13 preamp which is good, I prefer the MTK's but they have limited inputs & no remote in comparison. I wanted to try the SP14 & their ST70 but my experience with them wasn't stellar so I've kinda put them on the back burner. Skunkie designs just did a build video for the Tubes4hifi amp that kinda got me interested again. I have some chassis & transformers from the ST70 laying around. 

I really like the Van Alstine Ultimate PCB ST70. I use a sub so I  cut/roll off the bass on the Alstine amp around 50hz or so. I've built a couple of them at this point. Finishing another one up right now with transformers from Heyboer & Pacific Transformer. The OPT's from Pacific are cheap on price so I'm very curious how they will sound when complete. The owner insists that I'll be happy..we will see. First time I've used non-Dynaco iron. 

Pete Millet has some amp designs I'd like to try. He has some 50watt monoblocks that I just seen posted recently..though I'm not sure if he sells the PCB's for them on his eBay page. He has some amp projects on Wauwatosa Tube Factory WTFamps.com..i believe he still sells PCB's for some of those projects. 

Edcor Amps/Kits has links to DIY designs. 

Transcendent Sound sells full kits

Analog Ethos has very nice looking low powered kits. 

Specimen Products. Chicago based has an expensive SET & a couple other amp kits 

No personal dealings with those I listed..I just have them saved in my phone from when I was probably searching for kits/designs. 

PCB's & schematic designs are not kits though obviously. Like others have mentioned there are not a lot of full kits out there for sale. I'm hoping that if anyone  knows of any that exists to please mention them in this thread. Skunkie Designs has done a few low powered amp builds on her channel & posts all the parts needed. I wish I had the tools & skills to build the amp chassis/enclosure. If anyone knows of a place or person that will fabricate/cut out top plates for a fair price please mention it. 

At the moment I'm using a solid state class D Hypex Nilai DIY amp. High power extremely easy build. No soldering involved. I've paired it with a non-kit Icon Audio LA4 mkiii tube preamp that I did the Signature upgrade on. In my scenario I find the Nilai kit to perform & sound fantastic for the price. 

I forgot to add. To answer your original question I don't have any experience with low powered kits. But I'm interested in them. The one 8watt unit I heard was definitely good enough on speakers over 92db..4 & 8 ohm

@mattw73 Thanks for your detailed response. Very generous of you! The GU50 looks interesting and I like those guys too

@hilde45 no problem...I was just babbling on about whatever was popping into my head. Your thread is a topic I've been thinking more about recently though. I always just assumed one needed speakers with just a high sensitivity like 98db plus to be able to use an oldskool sound SET amp. Trying my Fritz speakers with a 25watt tube hybrid amp made me think that I might be able to get away with a low watt SET amp. 

I didn't have my Fritz when I listened to the GU50. I sold this guy an old pair of speakers & drove almost 2 hours to hear it & some other things he had. All of his speakers were older & mostly diy stuff. I just took his word for it that the couple speakers we listened to were 92-93db sensitivity when using the low powered amps. Everything sounded natural, big dynamic swings, clarity, just realistic. But I couldn't honestly say if my speakers would sound or could be handled the same way with low power. 

So I debate that if I'm really going to invest in a true SET amp that I should first build or own some speakers that where designed to really thrive with that type of amplification. Though I would take a chance on a good budget priced kit. Maybe it's all in my head but I do think there is something different yet enjoyable to a tube rectified single ended triode preamp & amp. 

I do think that going forward I will be more interested in diy & kit stuff..speakers included. I see now that I'm better off buying quality drivers using crossovers someone else designed & then implement quality parts. I've only done budget type preamp & tube amp builds but the outcome so far has exceeded my expectations. Low noise simple circuit tube gear sounds pretty good. 

I guess it just depends on where one is in their audio journey. If one is still out there striving to find the best sound possible then a kit is probably the very last thing on your mind. If you've gone that route, spent that cash, seen what you really get every time you up your budget & want to explore something really different..try some DIY. Get your feet wet with a kit that has great build instructions. Buy a soldering iron. It's kind of a cool feeling when someone comments that the stereo sounds good & I can say, thank you..I built that. My wife thinks it's amazing. I have yet to tell her that I'm just following someone else's instructions. 

Just my two cents, but having owned multiple ST70s and ST35s, I like the ST35 much better.

@hilde45 This is a comment worth exploring! The ST35 uses a triode Voltage amplifier while the ST70 uses a pentode. In addition, the smaller output transformers of the ST35 have wider bandwidth.

The input of the ST35 uses a 7247 tube, which is a 12AX7 section and a 12AU7 section in one envelope and is in current production. The 12AX7 section is the Voltage amplifier and the 12AU7 the driver. Since the 12AX7 is far more linear than a pentode (and has the most gain of any miniature triode) when feedback is applied, the tube distorts the feedback less (than a pentode) so the feedback is more able to do its job properly. This results in less higher ordered harmonic generation, so this is a much more interesting and relaxed amplifier to listen to and will fulfill your lower powered amplifier interest.

If one of these is properly built/refurbished it will give any SET a run for the money! It will play bass better, be more revealing (less distortion) and more neutral (less distortion).

And there’s a kit! Or there was. Their website says out of stock.

Go with the metal film option. Carbon resistors are really terrible.

Another source for pre-built all things Dynaco is: GetDynaco GETDYNACO.  My understanding is that Kenny Russell is the builder.  I have no connection to his products, but learned about them from the You Tube channel drD E Audio who uses a Kenny Russell ST-70 and Pas-3 preamp.  The combination sounds stunning with his Klipsch speakers.

Wow! Thank you @jetter and @atmasphere for the additional comments. The thread is really becoming a resource for others, as well as for me.

I built the Analog Ethos 2A3 Legendarium kit.

Perry is very helpful and the instructions are easy to follow.

Along with the instructions is a section explaining how it works.

Good parts, I didn’t feel the need to upgrade anything but the coupling caps.

You can download the instructions on his site.

I have to say though, a James Burgess 2A3 amp sounded a bit better for just a bit more money.

Have built several Audio Note Kits and thought they were very good for the money. Customers were very happy.

I have plenty of dynamics, no roll off at frequency extremes with my Tron 211 amplifier used with my Mhorn speakers rated at 93db. I easily get sound in the 90db+ in my 15x18 listening area.  It’s all about speaker matching and how well the amplifier is built in reference to power supplies.  The amplifier needs to have power reserves when needed. I have use 45, 2a3, 300b and 211 tubes in amplifiers I have owned over the years.  I agree with most on the 45 and 2a3 power output that you need 98db efficiency plus speakers(I prefer 100db +).  I used both of these tubes in Yamamoto and Triode Lab amplifiers with Klipsch Forted IV and that was in a larger room and was satisfied with the sound.  The 45 tube is the best sounding to me but your only going to get so much volume out of it and that’s a tube that I think needs 102db or better to get the most out of it unless your in a smaller room or near field setting.  PM me if you want to chat more about it.

Good luck

Don

@cfarrow Thanks for relating all that. Really interesting.

FWIW, last night I did some listening comparisons comparing the Sun Valley 845 vs. QS Mono 60 w/ KT77 tubes. I used my solid state amp (very neutral) and my Holo Spring DAC. All of my descriptions relate to how things sound in *my* room, of course.

Main impressions: Sun Valley 845's tonality was a bit softer, more detailed, further back in the soundstage, and slightly narrower soundstage (but very good); the bass was weaker, sometimes too weak. It was a bit less snappy in transients but still quite good—not sloppy at all. Instruments and voices had a bit more texture. It was very easy to listen to; never strident or approaching strident.

QS had better transients and dynamics by a bit; it had much better bass, and instruments were more forward in the soundstage. Voices and instruments were detailed but not as much, a bit less warm and intimate.

Overall: hard to say which is better. They were different, though both obviously tube amps. I suspect that a tube amp like the Sun Valley with a bit more grip on the speakers which keeps the intimate/texture/smoothness and improves the bass might beat them both. 

Not sure if any of this translates for folks, but sharing just in case.