@jbhiller Don't know why my @ didn't work on the last post...
The Audio Gods are tough but fair-Have you had the "Curse of the 300B" ?
These amps can really pull you in to hear the singer. The voice instrument is so spot on it can provide moments of disillusionment. For example, I've always preferred Sam Cooke's Live at the Harlem Square Club over Live at the Coppa. The former is way more free and pushes the R&B needle. It's musical and soulful. On my 300B setup I agree with that but I also can put Live at the Copa on and be drawn in... in so much that I start enjoying that album as much as Harlem Square. My attention gets focused on the music and not that this isn't my favorite Sam Cooke album. And I start hearing and feeling things in the vocals that weren't present before. It's wonderful in the truest sense.
The 300B SET also delivers smaller group instrumentals like no other. Drums in the jazz, acoustic/folk settings are sublime. You really identify the drum skins. You do this sonically more than viscerally. It is, however, intoxicating.
When done right these amps can be captivating. But the 300B mistress is not without its issues.
-You have to mate it with more sensitive speakers. This is huge. You are no longer looking at the lion's share of state of the art loudspeaker reviews. No. You are searching for sensitive, efficient speakers because the 300B runs out of gas real quickly.
-You have few choices in amps,
-You have few choices in tubes and they get really expensive for the 'premium' makes.
-You are likely listening at below moderate to moderate volumes.
-You may keep a second system to use outside of 300B time.
When I go back to push pull, or even solid state, I immediately appreciate the power and increased visceral impact. My attention, however, gets more easily lost, and while they don't sound "bad", I lose the clear window into pieces of the performance. Subtle nuances of how the singer's voice has personality arising out of the phrasing and tone of the vocal. Instruments with the 300B sound more "instrumenty". I don't consider any of what's lost when switching to push pull to be hyper detail or analytic. Instead, it's characteristics of the sound that aren't there leaving less of the inherent personality of whatever sound is being reproduced--vocal, instrument, or the room in which the performance is taking place.
And so I've done things with my system to help it when it's in 300B mode and push pull mode. For 300B, I added an REL subwoofer and a second Sumiko I had laying around. I use those to load the room and expand low end but increase soundstage and make things sound bigger with few watts. For the push pull setup, I've got the input source all tube whether digital or vinyl.
This leaves me with the feeling that the Audio Gods are tough but fair. It's hard to have it all with SET or PP. Nonetheless, my mind seems made up that it seems easier to work within the 300B setup to make it better as opposed to the push pull.
As a total aside, I am not the audiophile sage that many are on this forum or out in the audiophile-wild. I will say with confidence though that if you love hifi you owe it to yourself to spend a month with a SET amp coupled with efficient speakers.
The 300B SET also delivers smaller group instrumentals like no other. Drums in the jazz, acoustic/folk settings are sublime. You really identify the drum skins. You do this sonically more than viscerally. It is, however, intoxicating.
When done right these amps can be captivating. But the 300B mistress is not without its issues.
-You have to mate it with more sensitive speakers. This is huge. You are no longer looking at the lion's share of state of the art loudspeaker reviews. No. You are searching for sensitive, efficient speakers because the 300B runs out of gas real quickly.
-You have few choices in amps,
-You have few choices in tubes and they get really expensive for the 'premium' makes.
-You are likely listening at below moderate to moderate volumes.
-You may keep a second system to use outside of 300B time.
When I go back to push pull, or even solid state, I immediately appreciate the power and increased visceral impact. My attention, however, gets more easily lost, and while they don't sound "bad", I lose the clear window into pieces of the performance. Subtle nuances of how the singer's voice has personality arising out of the phrasing and tone of the vocal. Instruments with the 300B sound more "instrumenty". I don't consider any of what's lost when switching to push pull to be hyper detail or analytic. Instead, it's characteristics of the sound that aren't there leaving less of the inherent personality of whatever sound is being reproduced--vocal, instrument, or the room in which the performance is taking place.
And so I've done things with my system to help it when it's in 300B mode and push pull mode. For 300B, I added an REL subwoofer and a second Sumiko I had laying around. I use those to load the room and expand low end but increase soundstage and make things sound bigger with few watts. For the push pull setup, I've got the input source all tube whether digital or vinyl.
This leaves me with the feeling that the Audio Gods are tough but fair. It's hard to have it all with SET or PP. Nonetheless, my mind seems made up that it seems easier to work within the 300B setup to make it better as opposed to the push pull.
As a total aside, I am not the audiophile sage that many are on this forum or out in the audiophile-wild. I will say with confidence though that if you love hifi you owe it to yourself to spend a month with a SET amp coupled with efficient speakers.
66 responses Add your response
@jbhiller You’ve got to use some homebrew cables that are speaker level (spades, bare wire, or whatever) at one end and RCA at the other... use a multi-meter to check whether black or red is tied to ground at your SET output. That will then connect to the outer jacket of the RCA plug. The other wire will be your signal wire going to the RCA pin. If you’re driving only the F4 with your SET, you’ll also need to add a resistor across the SET’s outputs... probably somewhere between 8 and 16 ohms. When driving only the F4, your SET will essentially be unloaded, so you need to add some resistance to prevent damage to your tubes and transformers. Ideal resistance is whatever the SET was optimally designed to drive... and it should be easy to experiment to see if you get a cleaner signal when it’s seeing a particular load. If you’re using the F4 in a bi-amping setup, then you don’t need to worry about this aspect (as the SET will still be loaded by the midrange & tweeters). Note that Mark at RenoHiFi used to make these cables for customers, so perhaps you could pitch him to buy a pair if you don’t feel comfortable building your own. Also, I had some trouble decoding this from the writing, but all the quotes you see in the 6moons article are directly from Nelson Pass. I think he’d probably provide a bit of input too if you wanted to get it directly from the source. Unfortunately I haven’t yet implemented any of this, so it’s all still theoretical on my end. |
@cal3713 , This is very intriguing. I tried making sense of how to hook up the F4 and got a bit confused by the diagrams. I get that I'm running speaker wire from the SET output to the high level inputs on my loudspeakers. Am I running a duplicate speaker wire to the F4 and what am I hooking it up to on the F4? |
For people with poor matching speakers who still want some of the 300b set magic, there's also the possibility of adding a "booster amp" such as the first watt F4. As outlined in the below 6moons review, you can drive this amp directly from the speaker outputs of your set. The set provides all voltage gain and the F4 provides the full current necessary to respond to difficult loads. Depending on setup, the set can simply see a perfect 8 or 16 ohm load and thus can be run with minimal distortion. Or, as I will probably do with my Coincident PRE's, if you've got bi-amp compatible speakers, you can use the f4 to take the bass load off your primary amp. Because it has zero gain and is being driven directly by the set, you do not get the normal coherence issues that come with bi-amping. It's no longer available from new from FW/Pass, but thanks to the generosity of Nelson Pass et al. you can build one yourself for under $1k... https://www.diyaudio.com/forums/pass-labs/234355-guide-building-pass-f4-amplifier.html https://6moons.com/audioreviews/firstwatt6/f4_3.html |
Charles, it took me years of listening and then making amps to learn what you lay out above. You are so correct. Would anyone believe that my NAD M22 amp provides less believable bass than my 300b or my Primaluna push pull? It tests with virtually no distortion too. There’s no meat on the bones compared to these others than measure poorly in comparison. |
In the High End community/sector there are certain numbers often and proudly presented to presumably impress audiophiles. Very high amplifier output wattage Very high current (amperage) peak capacity Very low output impedance of amplifiers Very low THD i.e. 0.001range Very high damping factor i.e. 1000 and higher. When it comes to actual sound quality and listening to music I don’t believe that the above stated parameters are necessarily shown to be beneficial. Charles |
The High End ndustry norm seems to be 85 to 88 db sensitivity and a 4 ohm nominal speaker impedance.Yeah- I don't get that. It doesn't matter what kind of amp you have, if you make it work hard its going to make more distortion, and with **any** amplifier tube or solid state the distortion is always higher driving 4 ohms as opposed to 8 or 16. Speaker cables are more critical on 4 ohms too. I always thought high end audio was about making the playback sound like it was real, but so often it sounds like being able to weld with your amplifier is more important. |
If only we could have 200 watt 300b SETs...why oh why not!?Its the output transformer- with SETs its very difficult to get bandwidth as power is increased. This is true of push-pull too, but you don't run into problems until you have about an order of magnitude more power (+70 watts or so). What gives SETs a lot of that magic is the ultra low distortion at lower power levels. Most push pull amps can't do that- they have a minimum distortion at a certain low power level and below that power the distortion actually increases. It is possible to build a push pull amp that has a very low distortion signature at low power like an SET but to do that the amplifier must be fully differential from input to output. If the amp has a single-ended input combined with a phase splitter circuit its common to run into problems. |
I am a believer in the church of 300B. That said, I'm highly contemplating trading in my SETs for a push pull tube amp. I know full well I may go on to regret it...but I am at a place where I need more power 30-40% of the time, and I want to make the move to floorstanders. Nonetheless, 300bs have been a revelation, in what can be accomplished by modern stereo systems. I swapped out a McIntosh solid state integrated amp for the Allnic A-6000s, which with 300b xls tubes pump out 60 watts of SET glory. They make magic. If only we could have 200 watt 300b SETs...why oh why not!? |
Thanks Charles, I wasn't aware of those. I know what you are really planning is to buy these 2 300Bs https://tubedepot.com/products/nos-western-electric-engraved-base-300b-black-plate-late-1930-s-match... |
Facten, Canary audio has made a 50 W 300b amplifier for quite a few years now. Allnic I believe alSo currently builds a 50 W 300b. At one time VAC produced 140 watt 300b mono blocks with eight of these tubes per channel (16 300bs total !!!). I am glad that I have found much contentment with a single tube 300b per channel SET 😊. Replacing multiple 300bs can get expensive in a hurry. Charles |
Facten, Thanks for providing the link regarding the Thrax 300b amplifier, this needless to say is a beast as it weighs 120 pounds. I suspect that the transformers, chokes and power supply are massive and yet of outstanding quality. This is an (it seems) all out state of the art effort. 50 watts pure class A push poll topology. I wonder how much nuance, inner detail and intimacy of a SET (single 300b) it will capture/preserve? No doubt it will have impressive authority, dynamics and musical power with an appropriate speaker. I look forward to the review. IMHO what SET does best and sets it apart from other topologies is tone, purity, intimacy and emotional connection with music listening. Charles |
Monostereo magazine looks like it will be doing a review at some point on these 300B mono blocks - 50wpc class A Here's the Thrax webpage itself should you be interested in seeing them http://www.thrax.bg/Spartacus300.php |
My listening level is never more than 65-70db in a room measuring 15’D x 25’W. That’s plenty loud for me 😊96dB is at the upper end of moderate efficiency. You might think its playing loud enough, but if you ran an amplifier that was making less higher ordered harmonic distortion, you might not think so. If you really want to hear what a 300b can do, try a speaker with +101 dB sometime! |
Question: would 300b amplifiers work with my ~93dB efficient JBL 4430 studio monitors? Or do I need something more efficient than that?Unless you are playing the speakers nearfield you either will need more power or more efficient speakers. Again, an SET is best used when the maximum volume attained does not used more than about 20-25% of full power. Otherwise the amplifier starts making more higher ordered harmonics. If you've ever wondered why SETs are known for being so much more 'dynamic' than their low power would suggest, this is why: Those higher ordered harmonics are used by the ear to sense sound pressure and since music has a great deal of transients, the loudness cues (distortion harmonics) initially show up on the transients as you turn up the volume. This sounds to the ear is if its more dynamic but in reality its just distortion. Once you are aware of this fact, its also easier to hear that such is the case, so I may have ruinied it for you if this is how you use your SET. |
I have a $120,000 system in a dedicated listening room and it is amazing. My second system, in my living room, cost $20,000 and is comprised of a Cary 300 SEI integrated 300 B tube amp with Wilson Benesch Arc Monitors and an REL S/3 Subwoofer. I'm using a Prima Luna tube CD Player and speaker cables and interconnects are Nordost. I can honestly say that the 300B set up is every bit as enjoyable as the big system which cost 6 times more money. Both systems provide a completely different listening concept but the 300 B outfit is so sweet that I could live with it alone if I could not afford both systems! I have been buying and selling stereo equipment for 45 years and the 300 B is very special to say the least. |
Hi Mark, In my opinion Yes it would. However this depends on how loud you listen and what type of music you listen to. For jazz, acoustical or any analog music you will achieve healthy volume levels. If on the other hand you listen to bass heavy reggae/ska at loud volume levels and like to pressurize the room with bass- then the 300B will start to run out of steam. I listen to all types of music- including what's mentioned above. With my 97 db speakers the 300B has plenty or current and headroom to achieve very loud levels but I am able to make them clip if I am pushing heavy rock music loudly. In that case, I really like my KT150 single ended or perhaps my EL34 push pull amplifier. However for all music- the 300B single ended sounds better when driven within its power limitations. I hope this helps, Aric |
Here is another link you all may find interesting. Eddy's article covered a good deal of the basics, but one thing he really didn't go into is how the amplifier interacts with the loudspeaker. Since SETs run zero feedback for the most part, this is pretty important! So here's the link:http://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php Also FWIW, Eddy didn't cover the issue of distortion completely. One important thing he left out is that SETs have distortion that linearly decreases to measurable at lower power levels- this is the source of that 'inner detail' you read about in them so often. Most push pull amps don't do that; below a certain power level their distortion actually increases. But this is not true of **all** push pull amps; it is possible to build a push pull amp that shares the character of decreasing distortion to measurable just like SETs have. |
I get very satisfactory sound levels with my 300b monoblocks driving Proac 1SC, (86 dB./1W/1M), by biamping below 70 hz. To a pair of servo subs. Marchand 4th order passive xovers, drive a pair of Yamaha servo subs . 300B is addicting to listen to. Room is 24 by 12 by 8 high. Diy ,Je labs 300B monoblocks . Relieving the main speakers from reproducing bass, improves efficiency a great deal, while maintaining most of the charachter or the Proacs. Very happy . |
@glow_worm That is one of the best articles out there in that it explains clearly what is going on in a single-ended amplifier that contributes to what many of us hear as its "magic". Of course we can also see why push pull is so efficient. I read that article a few years ago and it is inspirational to me when I'm designing an amplifier. Of course, like all things audio- it can become addictive! So true to the audiophile "bug" I will be playing with some large transmitter tubes next (211/845). I also wanted to thank those that made mention of Aric Audio in this thread for the kind words :-) Best regards, Aric |
Yes, I'm in the SET cult too. I have multiple SET-ups, all driving various Klipsch heritage speakers. My main set is Cary 300B monoblocks driving Chorus speakers with a tube pre and mostly vinyl sourcing. But my second, and actually preferred set, is Bottlehead 45 monos driving La Scalas. Both are louder than I'd ever need, and obviously the La Scalas are even more efficient, but to my ears the 45 tube is slightly more detailed and musical than the 300b, which I consider a "rock-n-roll" tube. One day I'll experiment more with tube rolling these amps.... |
If any readers want an overview of SE vs PP, this is the best I’ve ever found. It’s clear and interesting: http://www.x3mhc.no/dokumenter/SE-v-PP-Part1.pdf |
facten, I just read the review. It is spot on. Here’s how. The Elekit 300B kit (with upgrades) does sound clear, like "water" as Herb Reichert says. Compared to my Primaluna Dialogue HP it sounds cleaner and has a special presence. The Primaluna is a great amp indeed, but it sounds fuzzier than the Elekit. The Elekit, despite having 1/4 of the wattage or even less, sounds open and unforced. The Primaluna sounds more aggressive and not in a bright way but like the sound is being pushed at me. The Elekit is really simple to build. I think Herb Reicher was a touch conservative in describing the effort in building the kit--just to be safe. It’s actually super easy and the directions are foolproof. Even if you’ve never soldered you could just buy a spare breadboard and some cheap resistors, watch a Youtube video on soldering and you’re good. The only downside of the Elekit is that I wish it had 2 sets of single ended/RCA inputs. Also, it would be sweet if there were instructions on how to formally bypass the volume attenuator so you could run it as an amp alone and then build two and do monoblocks. But that being said, I have 98dB sensitive speakers and I can get things rocking in a big for me room (15 x 23 x 10’ high). |
Hi Lalit, My Aric 300B SET is a stereo amp that Aric upgraded with Hashimoto transformers, Duelund coupling caps and WBT Nextgen binding posts and rca inputs. I’m using the EML XLS 300B tubes. Aric will soon make my amp into monoblocks with two external power supplies and C3M driver tubes with an interstage transformer. Fun times ahead!! Good luck with your 300B audition. |
@mac48025, Thanks for sharing your experience with 300B SET. I can hardly wait to hear the purity of 300B SET in my setup. My Canterbury’s are 96db so I should be okay with 8wpc. I got both Sophia Electric 300B Mesh and Royal Princess so it will be interesting to hear the differences between the two tubes. Would you mind sharing which 300B tubes you’re using with SET’s? And are you using mono’s or stereo amps? I would like to try EML 300B-XLS and Takatsuki TA-300B once I am settle with my amp selection. I also echo your experience with Aric, great guy. |
Theres no doubt that any of the 300B topologies can produce beautiful music but which is best for you will depend upon your system/room requirements and your listening preferences. I had Arics 300B SET and 300B PP amps side by side in my listening room and while the PP was a very good sounding amp it lacked the purity of the SET that I can’t live without. Others with different musical preferences than mine might prefer the power of the PP more but with the jazz and acoustical music that I normally listen to the 300B SET is magical. Ive talked to Aric and Gary of Border Patrol and they both agree with my assessment that the SET has a degree of purity and refinement that neither the PSET or PP can match but obviously they have their place, especially with less efficient speakers or those that want more power. I’ve worked with Aric through five different builds now and I can’t say enough for his expertise, professionalism, character and willingness to create the best possible product for your needs. |
@alexatpos, I would also suggest to contact Aric from Aric Audio. He is super knowledgeable with 300B design and possibly accommodate you with pretty much any customization available under the sun. I am in process of trying his newest prototype of 300B with SE and parallel designed amp all in one chassis. The amp has a complement of 300B x 2, EL84 x 2, OA3 x 2 and 5U4GB x 1. The amp is capable of 8wpc in SE mode or 16wpc in parallel configuration. |