I agree regarding the WAVAC. I heard a system with Venture speakers and the HE-805, some of the absolute best imaging and presence I've ever heard. Peggy Lee was in the room, singing to us. This was a big room and the Venture speakers were in the middle of the room.
SETs and Horns
- Thread starter Al M.
- Start date
Yeah, to respond to both you and @Al M. I am specifically talking cupped hands coloration which hit me on the Tunes and the old Cessaro Chopin for example. I do know some hear a plasticky coloration on AGs, but not sure i've spent enough time or hear that. I might hear a pair this weekend and let you know.
On the JBL article, I'd say that is a coherency issue not a coloration.
The Chopin had a massive cupped hand combination and was a poor speaker, like Wagner. Cessaro you have to go full horn size like Tang, Beethoven onwards. Liszt is poor as well, nice mids for amplified audiophile vocals, no connection to mid bass and below.
interesting. did you hear it on the Wagner too? I'd love to hear the new Alpha but at >$100k now
THe Tunes can have a somewhat insistent midrange but I would not have said "cupped hands". I am surprised that the Chopin had this effect because the mid range is primarily a high sensitivity direct radiator...I wonder if having the horn mouth pointing forward rather than down is impacting the midrange in that design. If I put my ear down on the floor by the opening of my Odeons there is a quite a bit of midrange but since it is going down to the floor it is not impacting on the midrange sound. Horning has their mouth pointing out the back (originally their speakers had it also going down to the floor). If it is pointing forward it might be audible and color the mids. I was having a discussion with another WBF member that we think the bass loading is actually a TQWT and not an exponential horn (Cessaro calls it "hornreflex") and that might let more midrange through than an exponential horn. I still need to hear the Wagner as people who have heard it at shows liked it but some on here did not.
Which JBL speakers?
There's a lot to unpack in this question! What is the amplifier being used to drive the horn? One of the reasons SETs are commonly used with horns as opposed to most push-pull amplifiers, tube or solid state, is that the latter usually use feedback, but not high enough amounts. The result is that the feedback adds higher ordered harmonics and intermodulations ocurring at the feedback node (re.: Crowhurst; we've known about this for over 60 years). These are easily heard on many horns, and is something that isn't that audible on SETs until you push them. But horn designers often need to be careful- the interface between the throat and mouth of the horn can cause trouble if not designed correctly. They don't sound fatiguing or agressive if designed and set up properly!
Clipping is easy to see, even with an SET, if you have an oscilloscope.
While I've no doubt the last sentence is true, the one prior to it simply cannot be, if this amp is class A, which I have to assume it is. Again, if an amplifier is class A, by definition it has 0dB of headroom.
As you know that review was written over 20 years ago; it appears that Bascomb accidentally shorted one speaker terminal to ground in his test rig (which is a very easy thing to have happen, for example if the signal generator and 'scope are both grounded). If this happens, the drive to the output tube grids becomes unbalanced, and a significant 2nd order will appear as a result (along with higher distortion overall).
If your amplifier is SET and not running feedback (because that will improve the measurements...), then the chances are very high that I can. In fact I can also say that a fully differential push-pull triode amplifier using an output transformer built to the same level of competence as expressed in your amp will have lower distortion and greater bandwidth. With regards to the MA-1, it has full power to 2Hz, so has unmeasurable squarewave tilt (IOW, less than 1 degree of phase shift) at 20Hz. No SET can do that and so will have less impact (phase shift in the bottom octaves robs the amp of impact). If you look at the specs of your amp, while the bandwidth is specified as you say, it does not say whether we're talking about +/- 1/2dB or +/- 3dB, or what. That really opens the door to variance; they could be 6dB off and still say that. Have you seen any measurements? I'd be quite curious to know how it really does.
But there is also the issue of what is meant by 'better'
FWIW we've never specced our gear to measure all that well (although I feel bandwidth is important); we've specced it to not make the higher ordered harmonics, due to the ear's sensitivity to them. In that regard, a cubic non-linearity is desirable as both the even and odd orders fall off at a faster rate. This is due to how distortion compounds from stage to stage in any amplifier if not eliminated in the prior stage. I'm not happy that our amps make distortion, but if one is pragmatic one has to accept that its going to be there.If you are referring to harmonics here, the ear treats the 2nd and 3rd the same way. The idea that the 3rd is hard is a myth; its the only odd ordered that isn't though.
My only dabble with horns which lasted 1 week due to serious lack of WAF. You can just see the transformers of the ANUK Ongaku behind the coffee table. I might try again one day....
Thank you for your answer. In my ears it was the K3rd. always more annoying than the K2nd because it was further away from the fundamental wave. I was wrong about that.
Last edited:
Sorry, you cannot say the ear treats 2nd and 3rd the same...they contribute different characteristics to the sound. 2nd is more open and 3rd is more “hooded”. Think trumpet vs. clarinet.There's a lot to unpack in this question! What is the amplifier being used to drive the horn? One of the reasons SETs are commonly used with horns as opposed to most push-pull amplifiers, tube or solid state, is that the latter usually use feedback, but not high enough amounts. The result is that the feedback adds higher ordered harmonics and intermodulations ocurring at the feedback node (re.: Crowhurst; we've known about this for over 60 years). These are easily heard on many horns, and is something that isn't that audible on SETs until you push them. But horn designers often need to be careful- the interface between the throat and mouth of the horn can cause trouble if not designed correctly. They don't sound fatiguing or agressive if designed and set up properly!
Clipping is easy to see, even with an SET, if you have an oscilloscope.
While I've no doubt the last sentence is true, the one prior to it simply cannot be, if this amp is class A, which I have to assume it is. Again, if an amplifier is class A, by definition it has 0dB of headroom.
As you know that review was written over 20 years ago; it appears that Bascomb accidentally shorted one speaker terminal to ground in his test rig (which is a very easy thing to have happen, for example if the signal generator and 'scope are both grounded). If this happens, the drive to the output tube grids becomes unbalanced, and a significant 2nd order will appear as a result (along with higher distortion overall).
If your amplifier is SET and not running feedback (because that will improve the measurements...), then the chances are very high that I can. In fact I can also say that a fully differential push-pull triode amplifier using an output transformer built to the same level of competence as expressed in your amp will have lower distortion and greater bandwidth. With regards to the MA-1, it has full power to 2Hz, so has unmeasurable squarewave tilt (IOW, less than 1 degree of phase shift) at 20Hz. No SET can do that and so will have less impact (phase shift in the bottom octaves robs the amp of impact). If you look at the specs of your amp, while the bandwidth is specified as you say, it does not say whether we're talking about +/- 1/2dB or +/- 3dB, or what. That really opens the door to variance; they could be 6dB off and still say that. Have you seen any measurements? I'd be quite curious to know how it really does.
But there is also the issue of what is meant by 'better'
If you are referring to harmonics here, the ear treats the 2nd and 3rd the same way. The idea that the 3rd is hard is a myth; its the only odd ordered that isn't though.
Thanks for writing this up in such great detail. I have to say that what you have described is almost a perfect match to what I have found over the years, and I absolutely agree with the need to multi-amp with SS for the proper bass and even mid-bass. My most recent experiments (and main system) are open baffle, but I found much of the same when I owned and used horns exclusively.
The ONLY thing I would even mention as a constructive question is your minimum 15 wpc assessment, and my reason for that is that for most SET owners, that means going to something like an 845 or PSET 300B...both of which I feel like have some trade offs on their own in the areas of micro-dynamics, from personal experience. I'm sure there are tubes and configurations (in really top amps) that I haven't heard and owned and of course I could be wrong, but in my case, for example, a properly designed PX4-driven amp at what is probably 8-9 wpc can produce both macro- and micro-dynamics that, in the case of micro-dynamcics, can exceed that of a top-level 845 SET or top-level 300B PSET (which I realize is not SET and comes with it's own trade offs). For selfish reasons I don't mention my PX4 amps much in forums so I don't have to compete with as many folks in finding good tubes on the market!
Can you give some examples of SET amp designs and driver/power tube combos that you feel maximize the 15 wpc SET range? My only first-hand experience is Thoress 845, Melody 845, and Audion Silver Dragon 300B PSET so I suspect there are many others that I could/should look into.
Some great posts on this topic!
I've built my system around SET amps, and agree with many observations here. While I acknowledge Ralph's many issues with SET I also agree with acg that they can work well if carefully implemented. I also think we see a lot of questionable amp/speaker pairings so unfortunately in many cases we hear non-ideal results.
In addition to what's stated already, I think it's best to consider the moving mass of the drivers (MMS) and power handling capability of the speaker the SET amp will power. You can get big full-range speaker systems with lots of drivers that have high efficiency, but that doesn't mean it's now a great candidate for a SET amp. That big speaker may be efficient but it also probably has high power handling and large MMS as well. I've found SET best in applications where MMS is kept to a minimum. In my system it's less than 3g for a 7W SET amp and it covers >400 Hz.
As far as SET for bass, there's more compromises...
- Large and expensive amps with high voltages required.
- Limited selection of woofers will work well.
- Woofers that work well have flexible cones so you need more of them to reduce excursion and limit distortion vs a modern woofer with a stiffer cone and more excursion capabilities.
- Electrical "grip" on woofer is not as good vs SS because of OPT, again requiring specific woofers and limited excursion for best results.
Basically, the ideal bass solution will necessarily be relatively larger in size and much more expensive.
SET bass makes more sense for a larger horn system where cost and space aren't as much of a consideration. I think it can match better with compression drivers in high gain horns too.
For smaller systems, I really like my horn-loaded 4.5" wideband midrange drivers. I think they are easier to match with an active bass solution vs CDs, and it can cover enough range you can listen near-field, you don't need nearly as much space as a 5-way system. Very easy to integrate into a living room, which is exactly the opposite of a 5-way system.
So horns can be really different in character, but I think SET works best for all of them... except for woofers in smaller systems.
I've built my system around SET amps, and agree with many observations here. While I acknowledge Ralph's many issues with SET I also agree with acg that they can work well if carefully implemented. I also think we see a lot of questionable amp/speaker pairings so unfortunately in many cases we hear non-ideal results.
In addition to what's stated already, I think it's best to consider the moving mass of the drivers (MMS) and power handling capability of the speaker the SET amp will power. You can get big full-range speaker systems with lots of drivers that have high efficiency, but that doesn't mean it's now a great candidate for a SET amp. That big speaker may be efficient but it also probably has high power handling and large MMS as well. I've found SET best in applications where MMS is kept to a minimum. In my system it's less than 3g for a 7W SET amp and it covers >400 Hz.
As far as SET for bass, there's more compromises...
- Large and expensive amps with high voltages required.
- Limited selection of woofers will work well.
- Woofers that work well have flexible cones so you need more of them to reduce excursion and limit distortion vs a modern woofer with a stiffer cone and more excursion capabilities.
- Electrical "grip" on woofer is not as good vs SS because of OPT, again requiring specific woofers and limited excursion for best results.
Basically, the ideal bass solution will necessarily be relatively larger in size and much more expensive.
SET bass makes more sense for a larger horn system where cost and space aren't as much of a consideration. I think it can match better with compression drivers in high gain horns too.
For smaller systems, I really like my horn-loaded 4.5" wideband midrange drivers. I think they are easier to match with an active bass solution vs CDs, and it can cover enough range you can listen near-field, you don't need nearly as much space as a 5-way system. Very easy to integrate into a living room, which is exactly the opposite of a 5-way system.
So horns can be really different in character, but I think SET works best for all of them... except for woofers in smaller systems.
Parsons, the first valve amp I built was the Melquiades of famous Cat origins. The 6C33C is low Rp, hence low output impedance and proved to be very transparent and capable power tube in my estimations. That breadboarded amplifier redefined what I thought SET amps, or any amps, could achieve in terms of realistic musical replay, and shone a glaring light on what it is that in my experience almost no other amplifiers are able to achieve. Listening was almost like being sat down in the headmasters office and given a thorough talking to in order to correct my ways. That amp is about 17 watts and like all SET's really does need to operate at about 10% (I am probably harsher in this estimation than many others) so >100dB/w/m sensitive speakers, but because of the low Rp it is more forgiving on normal (unfavourable) loudspeaker impedance loads. Micro and macro dynamics all in their right place.
But I do not like to spruik one particular set of tubes or another as the greatest or best. It is not so much the tube that makes the great system but how the tube is used and its place in making the sound you are after. Persistence, thoughtfulness, and perhaps a bit of luck. In my system, the preamplifier is at least as important as the amplifiers or loudspeakers...they operate as one, a team. The amps are specifically designed to work best with those particular loudspeakers and the preamp is designed to best run those particular amplifiers. At all stages sound quality is the ultimate goal.
I will say this about vacuum tubes though, and please take it however you see it, but in my experience I need some DHT somewhere in the chain. Get the filament supply right on those old darlings and there is nothing to compare. My preamp uses the 10 family of directly heated triodes and it has proved to be the absolute icing on the cake in terms of the 'realism'. Also, from my dealings with tubes, micro dynamics seem to be limited by B+ voltage and power rating of the SET amplifier. Smaller gaps and less output power means better output transformers which seems to mean better micro-dynamics and detail, a fairly loose analogy, hence using sequentially smaller SET amps for upperbass, mids and highs.
While I've certainly not heard everything out there, the 845/211 amps that I have heard seem to clump around like elephants. Bold, brazen, not a lot going on 'inside'. Maybe I need to get out more. I have heard a couple of Audion Amps including the Silver Night 300B PSE but they were mismatched to the speakers (bookshelf 2-ways!) and unfortuately displayed all the things that SET amps do when they are having a hard time.
Ralph, what about crossover distortion in push-pull mode? Do you agree that even in class A there is still some of it in push-pull designs, as argued in the main answer (by poster Neil_UK) to the question in this link?
Presence of Crossover Distortion in Class A Amplifier
This question is about theory facts of class A audio amplifier. It is known that class A amplifier is usually biased so that an amplifier's quiescent point is in the middle of the amplifying devic...
electronics.stackexchange.com
(I have to confess that I don't understand the technical argument. The poster answers critics in the small print comment section below his posted main answer.)
This link:
argues that while in class B crossover distortion is a significant problem, both in class A and class AB it is not.
The complete absence of crossover distortion in a SET circuit seems to be a main advantage constantly cited by its proponents. How significant is the issue in your view?
Interesting thoughts and I agree with your assessments. I found the 845 tube, like you, to be the SUV of DHTs...it simply ran over some of the micro-details and micro-dynamics too often vs. a 300B, PX4, 45 and 71a. It had a lot of punch, but ultimately was too heavy-handed for me. The PSET 300B had a similar issue for me, personally. I rolled a lot of tubes in each configuration (and at significant cost), but ultimately found the need to drop back a bit toward a lower WPC tube and amp. While I love my PX4 amp, I also own a very respectable second PX4 amp that is not as good, so it is definitely not all in the tube chosen, but the implementation, and of course the proper matching with pre-amp and speaker to the particular amp.
For Heights and Mids i woulder prefer SET 6-8 watt like this it Thomas Mayer Design,
a One Stage Tube Amp 6hs5 years ago build for other Forum as DIY Project.
Not for Newbies high B+ Voltage 1300 V, you need a good Power Supply and an excelent Output Transformer keep it simple when you want sound good my opinion.
the only thing is you need 2-3 volts rms at the input of the amplifier to get the maximum output power. or an Step up transformer 1: 2 or 1: 3 at the input of the amplifier.
vinylsavor.blogspot.com
Or look at this at his Website when you not want DIY.
For Bass you need more power to control the woofer like this PST Tube amp
Not expensive Tubes i hear it with some Blumenhofer Speakers sounds fantastic.
The advantage of an integrated amp is that if you have multi-way horn speakers you can adjust the volume sensitively to the horn driver.
a One Stage Tube Amp 6hs5 years ago build for other Forum as DIY Project.
Not for Newbies high B+ Voltage 1300 V, you need a good Power Supply and an excelent Output Transformer keep it simple when you want sound good my opinion.
the only thing is you need 2-3 volts rms at the input of the amplifier to get the maximum output power. or an Step up transformer 1: 2 or 1: 3 at the input of the amplifier.
Tube of the Month: The 6HS5
Hi! This months tube is a very special type with some extraordinary properties, the 6HS5. This is a quite 'modern' tube, developed in the ...
vinylsavor.blogspot.com
For Bass you need more power to control the woofer like this PST Tube amp
Not expensive Tubes i hear it with some Blumenhofer Speakers sounds fantastic.
The advantage of an integrated amp is that if you have multi-way horn speakers you can adjust the volume sensitively to the horn driver.
For Heights and Mids i woulder prefer SET 6-8 watt like this it Thomas Mayer Design,
a One Stage Tube Amp 6hs5 years ago build for other Forum as DIY Project.
Not for Newbies high B+ Voltage 1300 V, you need a good Power Supply and an excelent Output Transformer keep it simple when you want sound good my opinion.
the only thing is you need 2-3 volts rms at the input of the amplifier to get the maximum output power. or an Step up transformer 1: 2 or 1: 3 at the input of the amplifier. View attachment 75026
Or look at this at his Website when you not want DIY.Tube of the Month: The 6HS5
Hi! This months tube is a very special type with some extraordinary properties, the 6HS5. This is a quite 'modern' tube, developed in the ...
For Bass you need more power to control the woofer like this PST Tube amp
Not expensive Tubes i hear it with some Blumenhofer Speakers sounds fantastic.
The advantage of an integrated amp is that if you have multi-way horn speakers you can adjust the volume sensitively to the horn driver.
I had Cary monoblocks many years ago with the 572 tube and it does sound good but doesn't last very long...
This Mayer amp might have better bass with a good driver...which matters a lot in normal amp designs... it is often the driver that let's the whole design down!
For Heights and Mids i woulder prefer SET 6-8 watt like this it Thomas Mayer Design,
a One Stage Tube Amp 6hs5 years ago build for other Forum as DIY Project.
Not for Newbies high B+ Voltage 1300 V, you need a good Power Supply and an excelent Output Transformer keep it simple when you want sound good my opinion.
the only thing is you need 2-3 volts rms at the input of the amplifier to get the maximum output power. or an Step up transformer 1: 2 or 1: 3 at the input of the amplifier. View attachment 75026
Or look at this at his Website when you not want DIY.Tube of the Month: The 6HS5
Hi! This months tube is a very special type with some extraordinary properties, the 6HS5. This is a quite 'modern' tube, developed in the ...
For Bass you need more power to control the woofer like this PST Tube amp
Not expensive Tubes i hear it with some Blumenhofer Speakers sounds fantastic.
The advantage of an integrated amp is that if you have multi-way horn speakers you can adjust the volume sensitively to the horn driver.
hi, you know a set up with the Mayer 6cb5a and horns?
Yes. A Friend had it with Blumenhofer FS 3 for some years sounds really good , not like hifi ..just like music.
Not suitable for parties. sounds musical, airy and smooth with a very good resolution, he likes to listen to his music quietly .perfect match
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