Rex, your view on all this is super healthy and balanced. Even when you get it right it's natural for many of us (all of us on this forum?) to ask ourselves how to make it "more" right. There are many times where I have to just tell myself to stop touching stuff and listen. And usually when I stop touching for weeks and weeks (and weeks?) I can at least enjoy it for a bit and then I don't feel so anxious about it. None of this, to all of our points, is a slam dunk no brainer can't be contested.
SETs and Horns
- Thread starter Al M.
- Start date
Yes, I got my best bi-Amping results use two KR Audio VA-350s.
That said, I have also gotten really good results using a low and high power SET for my current two-way setup.
The fact that bi-amping with different tech doesn’t work well is for me a clear indication of just how much the amplification does impact the sound.
I find it hard to believe that you find all your amps sound similar. A friend of mine brings over his Devialet sometimes and it just kills the sound, flattens dynamics and spatial presentation. It is a profound change. He now has VTL monos that sound totally different from the Devialet and from my main SET.
I am actually much more tolerant of speaker idiosyncrasies than I am of amp electronic signature...
Furthermore, I essentially went to horn speakers because I wanted to get the best out of my SETs. Not the other way around. It took me effort to find horns, to gain the dyanmics and maximize my SETs without sacrificing coherence, transparency and low coloration that I already had with my large electrostats.
Ralf is not totally right about your 845 either. He is right that for sustained power you might have only 7 or so watts of really clean power but music is dynamic and most of the time you will be cruising at less than a watt and all you need are peaks that will be handled suitably and your amp will likely do that just fine. Unless you are listening very loud and cruising at several watts you will have plenty of headroom and the likelihood you will hear distortion on peaks is low.
I subscribe to this theory but have never really tested it other than superficially. My multichannel SETS all use the same driver tube but vary in that the power tube is different or they are single stage only. It works and is super coherent.
Whenever we are hearing differences between amplifiers, most of the time its all about the distortion they do or do not make, since the ear assigns a tonality to all forms of distortion. the rest of the time is if the speaker isn't a match for the amp so you can get a frequency response error, but since most speakers are anything but flat quite often that doesn't amount to much unless its a country mile off. This is because the ear seems to favor tonality induced by distortion over actual frequency response.
What happens in the case of nearly all SETs is that above about 20-25% of full power, the higher ordered harmonics come in to play. If your speaker has insufficient efficiency, in order to get the system to play loud enough the amp will be pushed into this area. Usually we're talking about transients since that is where the power is with a lot of music. When the higher orders show up on the transients, the ear interprets this as 'dynamic' and this is why so many SETs are described as being 'more dynamic than you would expect from a lower powered amplifier' in owner's and reviewer's comments. This is also the same reason why SET owners often say that 90dB is plenty loud enough, since the ear is using that distortion to determine how loud the sound is and is telling you its louder than it really is. Put another way, its not a good sign when it sounds loud when it really isn't!
IMO/IME the mark of a good system is that it never sounds loud, even when over 100dB. That requires all your ducks in a row; the source has to be unassailable by room vibration, the preamp as well and the amps unable to generate the higher ordered harmonics. If you tick all these boxes the system won't sound 'loud'. So you need efficient speakers for that (horns) even if you have an 845 as a power tube unless you're in a small room.
I've heard so many people comment about 'shouty' horns when its not really the horn's fault; I find that if you have enough power in reserve (and a lack of higher ordered harmonics) then that won't happen.
I think the issue is that this is yet another facet of music reproduction where there are significant individual differences in how the ear/brain hear and interpret these different types of distortion. We'll never all agree because we literally hear differently.
Ralph and I have both brought up this issue over on Agon in a few threads and I always end up citing a Nelson Pass article where he talks about how in his testing 1/3rd of listeners prefer 2nd dominance, 1/3 prefer 3rd dominance, and 1/3 do not differentiate (https://www.passdiy.com/project/articles/audio-distortion-and-feedback). As Ralph points out, everyone finds the higher ordered harmonics unpleasant.
Like you (and me), Nelson believes that 2nd vs. 3rd harmonic dominant profiles do indeed sound different. If anyone's curious, you can build one of Nelson Pass' BA3 front ends (https://diyaudiostore.com/collectio...roducts/burning-amplifier-gain-stage-for-ba-3), drop it in a box with a simple power supply brick, attach RCAs on the inputs and outputs, and then directly manipulate the balance of 2nd vs. 3rd harmonic distortion in your system by simply manipulating an on-board pot. $100 and you can see for yourself where your ears fall.
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I've got the same-series EML 20A (mesh) tubes on my preamp and absolutely love them. High linearity, low distortion DHTs that sound really great. And because they're modern production tubes, you don't have to play the Ebay lottery to find a good pair.
Voyager - Tron Electric
The Tron Voyager is a unique and very special amplifier, and has been a personal project for Graham for many years; as the concept of an OTA circuit he found both intriguing and challenging. It is a true OTA (One Tube per channel Amplifier). There are only three valves in the whole amplifier...tron-electric.co.uk
with emission labs 20B DHT
View attachment 75032
http://www.emissionlabs.com/datasheets/EML-20B.html
Sorry for the line of responses, I'm just now reading this thread and there's too much good content not to comment. I've resisted a bunch.
Anyway, Kingrex, this is exactly what I've found with my (non-horn) Coincident PREs. Every time I tried bi-amping I lost coherency, strikingly so. I've built my own amps and at one point was biamping with the exact same amplifiers on the top and bottom, and *still* there was a significant hit to coherency. Definitely not worth it in my estimation and like you I gave up on the venture (aside from subwoofer systems).
In reading about people doing multi-amp setups with big horn systems I really can't figure out why they're getting such a different result. Is it because horns are just less coherent, so it's not as obvious that the different amps are pulling the drivers apart?? I see people arguing that good horn systems do not have coherency issues, but I just can't get my experience to gel with the commonness of high-end bi & tri-amped horn systems. Would love to figure out why.
P.S. I'm considering buying a big horn system (maybe Sadurni), so I'm not criticizing, just honestly trying to figure out the inconsistency.
Thanks. I just emailed earlier today about setting up an audition once vaccinations happen. They appear to offer some additional value vs. the comparable AGs and the reviews are pretty positive. I've still only heard horns casually by wandering into various RMAF rooms on a trip almost 10 years ago, so I need to listen carefully and see if the typology really is for me. I am worried about coherence and horn coloration and want full range speakers that can play all genres. I've been rewarded every time I've simplified the circuits feeding my speakers and am attracted to horns for exactly the reason this thread was made. I loved my 300b SET monoblocks but had to move on because Coincident tricked me into buying their top of the line model by lying about amp compatibility/speaker sensitivity.
There a plenty of reasons why multiamping may not work and why any speaker, not just horns may not be as coherent as we wish. I am not even exactly sure what you mean by coherent as it may mean different things to different people, but it does not really matter. Large horns either require a large listening room so you can listen in the mid or far field, or a smaller listening room and listening in the near field, which is what I do, and which I prefer. The way that I listen requires physical time alignment of all transducers to the listening chair and a small sweet spot that is oh so sweet. My way is like a F1 race car, not very flexible, but so excellent for its task. The other way is more like a car in the Dakar Rally with driver and navigator and excellent performance but just not as fast as F1. For me, normal box speakers are more like mums SUV dropping a load of kids at school... gets the job done without any fuss and is very flexible in that it can tread both terrains with more passengers, but is not as fast as the race cars.
Big horns take dedication to setup and tune to race readiness. Something like the Sadurni is a good option because as far as I am aware it can be multiamped and physical time alignment of the channels is possible so you can listen in the near field if you want to... which I would recommend.
I have enjoyed my horns since 2008. Here is a videofrom this week where I mounted a new toy a Lyra Helikon mono ( a present from good friend and forum member ALF). 13 Watt bespoke SET with OPT's custom wound by Tribute for me some years ago. These feed 4 drivers per side with the Avantgarde subs having their own SS plate amps feeding 2 x 10 inchers per side.
On my Coincident PREs, I can separately amp the 2 x 12" drivers in the bass cabinets and the Accuton midrange/tweeter pairing in the head units. When I do so the music falls apart and sounds less "of a whole" than it does with a single amp driving everything. This is what I mean by a reduction in coherency.
Again, this happens even when the amps are identical, so differences in distortion profiles is not the reason. I presume the causal factor is small smearing effects created by imperfect alignment of the electrical signal as delivered to the different drivers which is especially problematic at the crossover frequencies. And perhaps its even more problematic in my PREs because the midrange units have no high-pass filter and the woofers play up into the 1000s. Their crossover filtering starts at 125Hz, but its a first order slope.
Maybe its less of an issue for some horn systems because you can more easily compensate for the electrical signal timing issue by changing driver distances?
That is exactly my issue with what Ralph has been writing around the internet that the 2nd and 3rd harmonic dominant distortion spectra will sound essentially the same due to masking but this is not correct. There are numerous commentaries that the 2nd sounds more open and "bright" whereas third dominated tends to sound "hooded". As to preference, Pass could be right about that and it would explain the difference in amp choice amongst people.
Agreed with high orders but I would point out that an all (or mostly) odd dominated spectrum will likely sound worse than a spectrum that has all harmonics in an exponential decay with increasing order. There is an article in Stereophile by Keith Howard where he adds distortion to a recording showed that, at least to his preference, the worst sounding addition he made was with all odd orders and the least offensive was an alternating even/odd pattern that decayed exponentially. The best overall of course was no added distortion...which he stated debunked the idea of "euphonic" distortion. This also fits with observations from earlier audio writers, like Jean Hiraga, who stated that a monotonic spectrum (meaning an exponential decay with increasing order) was preferrable (Cheever also made this claim). It turns out that only single ended circuits make such a pattern (unless a designer of a PP circuit deliberately unbalances the circuit to minimize the even order cancellation that PP circuits make).
I disagree that people all hear literally differently...there are more similarities than differences and this should all a psychoacoustic correlation between measurements and listener preferences. This is what Geddes was working on to some extent and also what Cheever attempted in his master's thesis (a good first start but inconclusive if his metric was really predictive or not).
I have seen this interesting box from Pass...have you built this and tried it out?
I have found that it is possible to blend very well when the amps are the same on both sections...or at least the same technology (ie. both SET or both PP tube or SS Class A). The timing differences in electrical paths would be extremely small compared to the time scales in an electro/mechanical system like a loudspeaker. The exception to that would be if there was some DSP applied to one set of drivers and not to another where the time delay could then be signficant.
I use a digital xover where the outputs are digital so I use my own DACs that are pretty simple DACs (no complex DSP or filtering) and so I think the signal runs through these DACs at about the same speed and the amps are very simple 2 stage SETs. So timing differences between the horns and the mid/bass drivers should be negligible compared to the phase shift from the filter itself. Of course having a mid/high horn allows me to adjust the timing to get the best blend.
Trying to blend an amp like a SET with something like a Class D amp has always been an exercise in frustration for me....I once tried to use them for sub duties but it was a fail.
Yes and no. I have it, but built and used it only as a gain device so I could match subwoofer levels. I've just started getting enough listening experience to pay attention to the distortion profiles and put together the pieces of why I like the gear I do. I'd go play with it as outlined above, but sadly have to pack up the entire system and put it into storage this week. Sold my house and am in transition land for a while. The house sale profits are what have me interested in trying a horn system.
And I totally agree with this, but don't have any other possible reason why biamping with identical amplifiers would have a negative impact in my system. I was sure it would be a positive, as I could double my power (and power supply reserves) while simultaneously reducing the speaker load on the amplifiers. Unfortunately that was not true. Regardless of causal factor, something got worse.
This is super interesting. When you are running it all of the same amp (i.e. not vertically bi-amping), are the two sets of drivers just connected via jumpers on the posts, or were they wired internally? I couldn't find a photo of the rear of your speakers. Also out of curiosity, how are you splitting the signal before the amps?
You weren’t biamping with an active crossover? You were still using the speakers own passive crossover, right? I have always used an active xover when biamping.
I removed all posts and use low mass pure copper clips to connect my wires (solid core silver throughout). My speakers have physically separate bass and head units, so there's no internal wiring to bypass. As you can see in the attached photos, I run two sets of wires directly from the amp to the speakers. I've tried jumpers, but prefer the separate wire runs.
I've tried a couple different ways to pull off the signal splitting, two sets of RCAs from different outputs on the preamp, and a switch on the amp that splits the signal from a single RCA input and sends it to two amplifier boards (each with independent power supplies). [As you can see, the amps are DIY -- highly modified/specialized First Watt F4s].
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Correct. I've played a bit with digital crossovers when I was trying a Lyngdorf TDAI-3400, but did not like the sound of the digital processing. I do use a miniDSP hd 2x4 on my sub units and it's really excellent (minus the low input impedance).
Also tough to bypass the passives in my speakers as I've got to get in there and cut wires just to try. Obviously this means my active crossover experience was sullied. Really just a way to remove the low frequencies from the 300b SET monoblocks I was also using at the time.
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