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Feliks Audio Arioso amplifier, or: Stereophile slides into irrelevance

Vuki

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I find the review highly entertaining, with lot of interesting musical references. Great review in spirit of Sound Practices magazine.
 

Koeitje

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8W? Seems like a good amplifier to drive Hifiman HE-6SE's or something.
 

escksu

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They were intended for monitoring of audio in remote situations, like a van. The beginning of desktop audio. Also: midbass boom instead of bass and overall eq focused on speech.

Midbass boom? I dont recall hearing any midbass boom in all my experience. Focus on speech, yes i do agree. Thats what makes them so awesome hen paired with the right equipment.

Perhaps you could describe more about what you meant by midbass boom.
 

escksu

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At about 83dB per watt he must have had to sit REAL close to hear anything at all without clipping from 8 watts a side. They are possibly the worst speakers in existence to use with a low power tube amp. I suppose their minimum impedance is high-ish at (I believe) 7.9 ohms, but this does not fix the sensitivity issue. But I guess if you run tubes at clipping, they do sound different from solid state :p.

Any evidence to back your claims?
 
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Robin L

Robin L

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Any evidence to back your claims?
Yeah:

"The measured voltage sensitivity was very low, at a fraction over 82dB/W/m. Low-powered amplifiers will not drive the speaker to very high levels, yet the limited dynamic headroom means that high-powered amplifiers are to be avoided—a paradoxical design indeed"

BBC LS3/5a loudspeaker 1989 Measurements | Stereophile.com

The frequency response shows that there is no "midbass boom" in the usual sense. There is a very slight bump in the midbass:

"In-room, the spatially averaged response (fig.2) holds few surprises: a lumpy upper bass, with no low bass to speak of; a basically smooth curve, tilted up in the top two octaves; the exact "subjective" curve, in fact, drawn back in 1976 by J. Gordon Holt on p.6 of Stereophile Vol.3 No.12. Measured in the woofer's nearfield, the -6dB point was a high 68Hz, the room reinforcing this only slightly to just above 50Hz. The degree of upper-bass boom means that the '3/5a must not be placed near the rear wall in an attempt to add bass weight. The result will be thick and muddy."

So if one attempts to increase bass by moving speakers to wall or corner, they will hear midbass boom. If they don't there will be little impression of bass. The same would apply to using traditional tone controls: the bass you'll get won't be the bass you want.

If John Atkinson was right, 30 years ago, then the LS3/5a will be a bad match for the Feliks Audi Arioso amp.
 

MaxBuck

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I have to say I find silly discussions of noisy, distortative tube amps to be much more entertaining than reading missives from people expounding upon audiophile USB cables and SSDs. The latter remind me too much of people who think COVID vaccine contains microchips.
 

escksu

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Yeah:

"The measured voltage sensitivity was very low, at a fraction over 82dB/W/m. Low-powered amplifiers will not drive the speaker to very high levels, yet the limited dynamic headroom means that high-powered amplifiers are to be avoided—a paradoxical design indeed"

BBC LS3/5a loudspeaker 1989 Measurements | Stereophile.com

The frequency response shows that there is no "midbass boom" in the usual sense. There is a very slight bump in the midbass:

"In-room, the spatially averaged response (fig.2) holds few surprises: a lumpy upper bass, with no low bass to speak of; a basically smooth curve, tilted up in the top two octaves; the exact "subjective" curve, in fact, drawn back in 1976 by J. Gordon Holt on p.6 of Stereophile Vol.3 No.12. Measured in the woofer's nearfield, the -6dB point was a high 68Hz, the room reinforcing this only slightly to just above 50Hz. The degree of upper-bass boom means that the '3/5a must not be placed near the rear wall in an attempt to add bass weight. The result will be thick and muddy."

So if one attempts to increase bass by moving speakers to wall or corner, they will hear midbass boom. If they don't there will be little impression of bass. The same would apply to using traditional tone controls: the bass you'll get won't be the bass you want.

If John Atkinson was right, 30 years ago, then the LS3/5a will be a bad match for the Feliks Audi Arioso amp.

Regarding that, yes, placement of the LS3/5a is quite crucial. I really dont think these little speakers are good at bass. I would say they are more for stuff like jazz.
 
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Robin L

Robin L

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Stereophile Recommend Components 2021 Awards

Air Tight ATM-300R: $18,500 with Electroharmonix 300B tubes
AD, who was on record as having "never heard a single-ended 300B amp that I disliked," was especially smitten by this compact yet remarkably heavy (54lb) stereo amplifier: a three-stage design in which 12AU7 and 12BH7 dual-triodes are used as voltage-gain stages and drivers, respectively. The output tubes are a single 300B per channel, specified to output 9W each. Distinctively, the ATM 300R uses global feedback, but tapped from the primary rather than secondary side of each channel's output transformer. AD heard from the Air Tight amp "startling . . . details of musical nuance," "lusciously textured and colorful" strings and woodwinds, "realistic force" in its reproduction of timpani, and the ability to sound surprisingly big. He also made special mention of the ATM 300R's way with orchestral double-basses, noting their "depth and power, and far greater clarity of pitch than I've heard through any other 300B amplifier, bar none." Re-auditioning the amp in his newly modified listening room, through vintage Altec Flamenco loudspeakers, confirmed those positive impressions, and then some. Writing from his test bench, JA described the Air Tight as "well engineered," praising in particular its apparently "excellent output-transformer design." (Vol.41 No.2, Vol.42 No.11)
And here's the [dire] lab results from Stereophile:
Air Tight ATM-300R power amplifier Measurements | Stereophile.com
 
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Robin L

Robin L

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Regarding that, yes, placement of the LS3/5a is quite crucial. I really dont think these little speakers are good at bass. I would say they are more for stuff like jazz.
These were purpose-built speakers, meant to be thrown into a remote van to monitor radio broadcasts. I don't think these speakers are good for music [I had access to a pair]. Limited dynamics, no real bass, fussy for use in a typical space [but they really weren't intended to be used that way.] I can understand why tubaholics go for the LS3/5a on account of its high impedance, but the speaker can't play loud, can't play deep. Typical high-end cultism: does one thing right if you throw too much money at it.
 

dtaylo1066

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$6,500. Certainly a 100% subjective review, replete with embellished metaphors. In respect of or alliance to objectivity, why bash the design if we have no real data about it?
 
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Robin L

Robin L

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$6,500. Certainly a 100% subjective review, replete with embellished metaphors. In respect of or alliance to objectivity, why bash the design if we have no real data about it?
Because, being a classic SET design, it has a very high probability of having a distortion profile that looks like this:

119ATM300fig07.jpg
 

A Surfer

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Not to mention the cost per watt is nothing short of obscene, regardless of the existence of even worse offenders in the marketplace. Tubes are sexy, absolutely, but this type of product is clearly made for those who have significant amounts of disposable income and can afford to overpay in such a manner.
 

Freeway

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They were intended for monitoring of audio in remote situations, like a van.

Like a 'white' van? One rolled up and tried to scam me at a red light. Actually I did pull over to have a peek inside.
 

A Surfer

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Like a 'white' van? One rolled up and tried to scam me at a red light. Actually I did pull over to have a peek inside.
Too funny. I would totally have wanted to. I was approached once with the infamous extra speaker deal in a shopping centre parking lot, but I was in a hurry and couldn't look.
 

Koeitje

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Regarding that, yes, placement of the LS3/5a is quite crucial. I really dont think these little speakers are good at bass. I would say they are more for stuff like jazz.
Yeah....no, if you listen to any jazz involving a double bass these are terrible speakers.
 

rex4539

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I would love to listen to this amp paired with Klipschhorns. I'm quite confident it would sound divine.

Of course, if you have the budget for Klipschorns, there are much better (and stronger) tube amps to choose from.

So perhaps repurposing it as a hi-end headphone amp would not be a bad idea.
 

escksu

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Yeah....no, if you listen to any jazz involving a double bass these are terrible speakers.

I don't know much about jazz as they are not my type of music. But from my experience, I do know vocals sounded very good on the LS3/5a.
 
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