A case for warm (vintage) amplifiers

[AJM1981]

Aha. Nice speakers. From what I can see the manufacturer's stated sensitivity is 88 dB. Let's say that's true (manufacturers have a penchant for exaggerations). With then 10-15 amp watts. Then it mostly depends on how high the volume you play and whether you play with very dynamic music or not.
"Normal" dynamic jazz, blues, pop, rock recordings at a "normal" let's say 65 dB listening volume are fine. Or at least they would have been for me under those conditions.
(I would have added a subwoofer, but that's another matter)

Thanks. I would like to make a point connected to the dynamics. I used the Duke Ellington track example of a bright chord burst at the beginning, followed by the rest of the track in a slightly lower gain. There are similar dynamics in the beginning of the original tubular bells recording, when the passage starts with the motive at a lower gain followed by the grand piano (and layered effect) "hit" that towers way up in gain.

The voicing of the two amps mentioned is kind of what keeps the balance in dynamics. It softens the raw edges in some frequencies leading to a solution other than compression, that also solves it. With modern voiced amps (the ones being described as analytical) compression is the solution been moved to, to stitch things together.

Recording technology and how it has developed and philosophy around recordings. Commercial aspects (loudness war for example) also have to be weighed in. There is a lot to be said about it. Here is an AI summary of a number of threads, from different forums, regarding the question of:
The best recording of Kind of Blue:
View attachment 483732View attachment 483733
I leave aside how right or wrong it is regarding what is being said regarding the AI compilation (a topic for a new thread here on ASR?). I'm just stating that discussions exist.

There was a bit of 'for radio' emphasis in the 60s and 70s. But the loudness war as we know it as a debated topic started taking off "publicly" after the CD was introduced in the 1980s, which opened up the pandora's jar of experimenting (it did not have the physical limitations of a record and a needle, bass could be cranked up).

The CD was an excellent medium, but it was abused. First of all to 'highlight' clarity for showroom purposes, followed by the infamous loudness war, leaving a bad taste to more modern "consumer-purists" history

Even modern recordings. For example this superbly good album (the music not the recording). Steven Wilson later fixed the recording though:

They have murdered "Tears for Fears" ... digitally!

Check this out: https://magicvinyldigital.net/2022/03/04/tears-for-fears-the-tipping-point-review-lp-cd-qobuz-tidal-amazon-atmos-blu-ray-audio/ ALL the existing digital formats are screwed! The compression, the clipping! Quoting my buddy Danny: "The sound engineers should be shot. Out of a...

www.audiosciencereview.com

That debate all formed later on, in times of these amps' rollout on the market, the CD was not even a prototype yet.

 

[DanielT]

The voicing of the two amps mentioned is kind of what keeps the balance in dynamics. It softens the raw edges in some frequencies leading to a solution other than compression, that also solves it. With modern voiced amps (the ones being described as analytical) compression is the solution been moved to, to stitch things together.

Don't forget to factor in what your speakers can do. Your Denton 85th has, for the size of that speaker, about the expected roll of f3 60 Hz for example:

Wharfedale Denton 85th

Wharfedale Denton 85th Anniversary loudspeaker review

www.hi-fiworld.co.uk

As long as you don't push your amps into clipping and you let them operate at the level where they have the lowest distortion, I have a hard time believing that they color the sound, or soften the raw edges in some frequencies (at an audible level). Unless you fiddle with the tone controls that is.
But okay, low powered amps in combination with dynamic music at a higher volume, amp clipping may occur but it does not soften the raw edges.
On the contrary creates the opposite of a soft sound.

There was a bit of 'for radio' emphasis in the 60s and 70s. But the loudness war as we know it as a debated topic started taking off "publicly" after the CD was introduced in the 1980s, which opened up the pandora's jar of experimenting (it did not have the physical limitations of a record and a needle, bass could be cranked up).

Speaking of cranked up, or higher volume. That was the problem with the loudness war. Volume at the expense of dynamics.

 

[AJM1981]

Don't forget to factor in what your speakers can do. Your Denton 85th has, for the size of that speaker, about the expected roll of f3 60 Hz for example:

That is true for the Dentons. Though the treble roll off is just one factor and having a nad amplifier connected to them also gives a totally different signature in which things are more 'straight in the face' sounding. And for that I know that this is where I would argue as a producer "it should be like that" and as a consumer "it does not have to be like that".

Wharfedale Denton 85th

Wharfedale Denton 85th Anniversary loudspeaker review

www.hi-fiworld.co.uk

Speaking of cranked up, or higher volume. That was the problem with the loudness war. Volume at the expense of dynamics.

I read the Dire Straits' Brothers in Arms was a showcase for a louder endproduct and that the stretch that digital media provided was key to creating the monster of Frankenstein (the loudness war). : )

But this so much hated phenonema you demonstrate here really kicked-off in the 1990s with growing criticism following in the early 2000s. It was not even a topic in times these amps in the openingpost were on the market. But in terms of a different spotlight on even making "heavier shouting parts" palpable a "warmer sounding amplifier" is in my opinion the way to go alternatively.

More of a solution at the end over a solution in content treatment.

Luckily the loudness war as your example showed is kind of on its way out again. Mastering engineers also keep eyes on these discussions.

 

[DanielT]

That is true for the Dentons. Though the treble roll off is just one factor and having a nad amplifier connected to them also gives a totally different signature in which things are more 'straight in the face' sounding. And for that I know that this is where I would argue as a producer "it should be like that" and as a consumer "it does not have to be like that".

Amplifiers and sound signatures, you and I have a different view regarding its impact. That there are measurable differences between different amplifiers is an objective fact, but when do these differences become audible? It is a favorite topic here at ASR, that is, when does it become audible? Audibility then regarding everything that has to do with what you pop into the hi-fi sound chain.

But okay sometimes amplifiers can actually create a sound signature but then they must be considered poorly designed amplifiers (which your Sansui amplifiers are not), such as this one:

Dayton Audio HTA20 Hybrid Tube Amp Review

This is a review and detailed measurements of the Dayton Audio HTA20 Hybrid stereo tube amplifier with included DAC and Bluetooth. It is on kind loan from a member and costs US $185. This is a cute looking tube amp! It even has the obligatory enclosure for a transformer (don't know if there is...

www.audiosciencereview.com

I read the Dire Straits' Brothers in Arms was a showcase for a louder endproduct and that the stretch that digital media provided was key to creating the monster of Frankenstein (the loudness war). : )

What a coincidence that you mention Dire Straits' Brothers in Arms because here is an ongoing thread about about that record:

Brothers in Arms in 2025, 40 th anniversary : Which Format Delivers the Best Sound? CD, LP, Streaming, Blu-ray, SACD, Stereo to Atmos

"Brothers in Arms" is the fifth studio album by Dire Straits and remains the band’s greatest commercial success, with over 30 million copies sold worldwide, including around 2 million in France. Released in May 1985, the album received a Grammy Award in 1986 for Best Engineered Album...

www.audiosciencereview.com

 

[pinger]

Unless someone can show a repeatable double blind A/B test that can identify sonic differences between two properly functioning SS amps they all sound the same IMO. I'll wait for the test.

 

[mhardy6647]

The definition of 'properly functioning' may be tricky here. Capacitor-coupled solid state outputs will most likely perform measurably and (possibly also) audibly differently than a direct-coupled ss (power) amplifier stage.

 

[pinger]

The definition of 'properly functioning' may be tricky here. Capacitor-coupled solid state outputs will most likely perform measurably and (possibly also) audibly differently than a direct-coupled ss (power) amplifier stage.

"possibly also" Kind of what I'm getting at!

 

[AJM1981]

It would be easy money for anyone here to select the au505 in a double blind test compared to a more revealing one. I would maybe not be able to pick it when it would be compared to another random warm voiced amplifier. Altough I perhaps would at lower gain levels and its high "presence" level.

Will leave out the lighter au101 in this claim as it is best with its loudness contour on as mentioned, and that would be cheating if no aides would be virtually allowed

 

[mhardy6647]

back in the old times, "they" (ahem the manufacturers) were pretty good labeling 'flat' attenuators as VOLUME (or LEVEL), and contoured attenuators as LOUDNESS. This was even true on low-end equipment (all-in-ones, e.g.). Admittedly, not something one can take to the bank, so to speak -- but if the attenuator's labled VOLUME, it is probably contour free.
Check the schematic!

Not to drift too far into the weeds -- but in the good old days, when hifi was taken pretty darned seriously, it wasn't all that uncommon to find variable VOLUME and LOUDNESS.


OK, this Sherwood has a GAIN adjustment (secondary control -- but it's there) and variable LOUDNESS.

EICO HF-20 (random internet photo, although I once had its big brother, the HF-52, which was similarly configured. I do miss that integrated "monoblock"!)

More recently -- Yamaha's offered variable loudness for decades (albeit not so much in recent years).

 

[DanielT]

It would be easy money for anyone here to select the au505 in a double blind test compared to a more revealing one. I would maybe not be able to pick it when it would be compared to another random warm voiced amplifier. Altough I perhaps would at lower gain levels and its high "presence" level.

Will leave out the lighter au101 in this claim as it is best with its loudness contour on as mentioned, and that would be cheating if no aides would be virtually allowed

I'm not so sure about that. Consider, for example, that speakers can have upwards of ten times more distortion than the au505. That in itself makes it quite difficult if you for example you plug in an amp that has ten times less distortion than the au505 and do a blind test between them*. After all, it's the speakers in both cases that produce the most distortion. So how easy will it be to tell the amplifiers apart in a blind test? Maybe with a lot of practice and ultra-low-distorting speakers. But the au505 has I can see around 0.07% distortion at 10 watts. At least it's not something I can hear with music.
*provided that the au505 is not driven into clipping during such an amp blind test

Check this out, with only 8 watts and at best 1% distortion with this tube amp:

Record breaker: Raphaelite CS30-MKII tube amplifier review and measurements

Raphaelite CS30-MKII 300B integrated tube amplifier review: A New Performance Record This is a review and detailed measurements of Raphaelite CS30-MKK 300B single ended tube amplifier. It is available on eBay for $1449 + $310 shipping to California + tax. There are some better deals from...

www.audiosciencereview.com

..........this is how it turned out in a blind test of Raphaelite CS30-MKII tube amplifier vs:

Take the blind challenge! 300B SET vs. Straight Wire with Gain

The challenge: How does a budget 300B SET compare to a "straight wire with gain"? You tell me. It's time to put your ears to the challenge. Poll is open for 14 days. No peeking at the results. Test Setup: I connected a Topping D90, set it at 0 dB volume, to a budget 300B single-ended...

www.audiosciencereview.com

 

[DSJR]

Those old Sansui amps are very much loved over here.

 

[AJM1981]

I'm not so sure about that. Consider, for example, that speakers can have upwards of ten times more distortion than the au505. That in itself makes it quite difficult if you for example you plug in an amp that has ten times less distortion than the au505 and do a blind test between them*. After all, it's the speakers in both cases that produce the most distortion. So how easy will it be to tell the amplifiers apart in a blind test? Maybe with a lot of practice and ultra-low-distorting speakers. But the au505 has I can see around 0.07% distortion at 10 watts. At least it's not something I can hear with music.
*provided that the au505 is not driven into clipping during such an amp blind test

Check this out, with only 8 watts and at best 1% distortion with this tube amp:

Record breaker: Raphaelite CS30-MKII tube amplifier review and measurements

Raphaelite CS30-MKII 300B integrated tube amplifier review: A New Performance Record This is a review and detailed measurements of Raphaelite CS30-MKK 300B single ended tube amplifier. It is available on eBay for $1449 + $310 shipping to California + tax. There are some better deals from...

www.audiosciencereview.com

..........this is how it turned out in a blind test of Raphaelite CS30-MKII tube amplifier vs:

View attachment 484143

Take the blind challenge! 300B SET vs. Straight Wire with Gain

The challenge: How does a budget 300B SET compare to a "straight wire with gain"? You tell me. It's time to put your ears to the challenge. Poll is open for 14 days. No peeking at the results. Test Setup: I connected a Topping D90, set it at 0 dB volume, to a budget 300B single-ended...

www.audiosciencereview.com

When someone would sit in a listening room with the evo 4.2 and i would label the au505 number 1 and my Nad number 2 playing a couple of songs, It would be darker and fresher in opposites. The au505 has the slight illusion of loudness contours without it being active (one of those old amps that does not really need that switch, it sends it over the top), so low volume listening would spoil it already in the sense of presence. The emphasis is on different frequencies as well. The bolder voicing of the au505 perhaps makes it more engaging for classic rock and jazz and a little less engaging with electronic dance music and snappier pop and rock.

 

[audio_tony]

I find this thread quite interesting.

This may be off topic - but only this morning I was pondering one of my early systems (a Realistic SA-800 amp, Trio KD1033 turntable, Ortofon FF15E cartridge and Realistic Minimus 10 speakers). Looking back, I thought the sound I had back then was more satisfying than various modern kit I've owned in the past 20+ years.

The bass in particular seemed better. I still have the SA800 amp and Minimus 10 speakers - I should connect them up one of these days, maybe I'll find my audio nirvana again lol...

There is a tongue in cheek element to this post....

 

[DanielT]

When someone would sit in a listening room with the evo 4.2 and i would label the au505 number 1 and my Nad number 2 playing a couple of songs, It would be darker and fresher in opposites. The au505 has the slight illusion of loudness contours without it being active (one of those old amps that does not really need that switch, it sends it over the top), so low volume listening would spoil it already in the sense of presence. The emphasis is on different frequencies as well. The bolder voicing of the au505 perhaps makes it more engaging for classic rock and jazz and a little less engaging with electronic dance music and snappier pop and rock.

What NAD amplifier do you have?
If I skip this with distortion and take up frequency response. It affects more, the fact is that a good FR is the most important thing to have. I think most hifi enthusiasts would agree with that. IF your amplifiers do not have a straight FR, let's say that the tone controls affect, (even if they appear to be in the zero position) then there is absolutely a possibility of hearing differences. We are quite sensitive to differences in FR. A few dB may be enough. Maybe just one dB. You can test here:

Blind Testing a 1 dB Level Difference

Discover the smallest difference in level (dB) you can reliably hear.

www.audiocheck.net

By the way, speaking of practicing and that practice makes perfect. I practiced, for example with lots of quick A/B tests, so that I could finally hit the mark every time at the 1 dB level while listening with headphones.

 

[AJM1981]

What NAD amplifier do you have?

A 314, rather spartan amplifier. Mid 90's.

If I skip this with distortion and take up frequency response. It affects more, the fact is that a good FR is the most important thing to have. I think most hifi enthusiasts would agree with that. IF your amplifiers do not have a straight FR, let's say that the tone controls affect, (even if they appear to be in the zero position) then there is absolutely a possibility of hearing differences. We are quite sensitive to differences in FR. A few dB may be enough. Maybe just one dB. You can test here:
View attachment 484218

Blind Testing a 1 dB Level Difference

Discover the smallest difference in level (dB) you can reliably hear.

www.audiocheck.net

By the way, speaking of practicing and that practice makes perfect. I practiced, for example with lots of quick A/B tests, so that I could finally hit the mark every time at the 1 dB level while listening with headphones.

Well trained

I find this thread quite interesting.

This may be off topic - but only this morning I was pondering one of my early systems (a Realistic SA-800 amp, Trio KD1033 turntable, Ortofon FF15E cartridge and Realistic Minimus 10 speakers). Looking back, I thought the sound I had back then was more satisfying than various modern kit I've owned in the past 20+ years.

The bass in particular seemed better. I still have the SA800 amp and Minimus 10 speakers - I should connect them up one of these days, maybe I'll find my audio nirvana again lol...

There is a tongue in cheek element to this post....

Bass character ís also a thing. It seems mainly a choice for a high damping factor for modern amps and a lower damping factor for more traditional voiced ones.

The latter does not seem a very popular choice nowadays, maybe because a higher damping factor gives a tighter bass which is favored, but it also creates "far more" room to a subwoofer "connection", which as a device has taken its commercial position in a newer landscape of hi-fi after the 70s (maybe a reason? Didnt look into this direction yet). There are some exceptions, but "the hifi consumer market" seems centered around the higher side.

With the sansui and films there is quite a "full picture of sound", it is cinematic with a broader deep bass with character through my Wharfedale Evo 4.2. That have more woofer headroom which most modern amplifiers don't really utilize, the au505 does.

I would maybe like to, as a careful hypothesis, throw in the coin that when the consumer market would to the wider extent embrace a low damping factor (again), that it would perhaps nót make a big part of the subwoofer market obsolete, but it would occupy and bloom into frequency territories that would create more doubt about the need for that very last bit. I own a decent small B&W sub for a couple of years. With the sansui it made me doubt its smaller "frequency shade" and its use. I didnt really miss it when it was turned off.

 

[audio_tony]

Bass character ís also a thing.

I suspect what it amounts to (for me at least) is that my early system(s) had a characteristic bass 'bloom' which was likely down to damping factor or just lousy speakers, whereas my 'modern' system(s) all seem to have precise, tight bass (but seemingly not as deep* as my older systems).

It's quite difficult to quantify really.

*the modern systems probably go deeper I suspect. But deep bass isn't always 'quality' bass if that makes any sense.

 

[AJM1981]

I suspect what it amounts to (for me at least) is that my early system(s) had a characteristic bass 'bloom' which was likely down to damping factor or just lousy speakers, whereas my 'modern' system(s) all seem to have precise, tight bass (but seemingly not as deep* as my older systems).

It's quite difficult to quantify really.

*the modern systems probably go deeper I suspect. But deep bass isn't always 'quality' bass if that makes any sense.

I get the theoretical sketch though there are different ways to look at it. If modern amps would do it like sansui did, it would spoil parts of the current marketing ecosystem in which every hi-fi household needs a subwoofer as the range from the bottom end of frequencies of the woofer to the sub would be smaller.

A few explanations of why there was a shift from a lower to a higher damping factor

1. The Solid-State Revolution and the Rise of Negative Feedback

· The Problem: Early transistor amplifiers (late 60s/early 70s) often sounded terrible—harsh, brittle, and prone to a flaw called Transistor Distortion (Crossover Notch Distortion). This was audibly unpleasant.
· The "Solution": Engineers discovered that applying large amounts of Global Negative Feedback (NFB) was a highly effective way to measure much lower levels of Total Harmonic Distortion (THD) and eliminate crossover distortion on the test bench.
· The Unintended Consequence: High NFB inherently creates a very low output impedance, which translates directly to a high damping factor. This became the easiest path to making a solid-state amp measure well, even if it didn't always sound best.

This was kind of the pre-revolution , if we may call it that way.

2. The Ascendancy of "The Spec Sheet" and Objectivism

· "The New Religion": In the 1970s, hi-fi moved from a niche hobby to a broader consumer market.

Thank the masses and the marketing of audio possibilities.

Manufacturers needed simple ways to differentiate their products. A spec sheet with impressively low distortion figures (0.005% THD!) and a high damping factor (200!) became powerful marketing tools.

· The "Straight Wire with Gain" Ideal: The new philosophical goal for an amplifier became complete transparency—to add or change nothing. A high damping factor was framed not as a "sound," but as the absence of a sound—the ultimate control and accuracy. This objective, measurement-driven approach was championed by influential figures like Matti Otala (who critiqued TIM distortion) and publications like Stereo Review.

In short.

'Amplifiers should not have a sound signature of their own'

it was literally a statement in a new vision according to a new philosophical movement, also heavily advocated by Peter Walker (Quad) and utilized in the 303. This philosophy seems also a little bit on its way out again these days.

3. The Demands of New Speaker Technologies

· The ESL-63 and Planar Magnetics: The launch of the Quad ESL-63 electrostatic loudspeaker in 1981 was a landmark. Electrostatic and planar magnetic speakers (like Magneplanar) present a brutal, highly reactive load to an amplifier. A low-damping-factor amp could easily lose control, distort, or even oscillate and self-destruct.

Speaking about wrong pairings. With electrostatic loudspeakers it literally was about life and death (for the gear).

This was with a growing consumer market a problem not to underestimate those days. Especially because no one really knew what path hifi would go in general. Electrostatic loudspeakers were once embraced as the future of hifi. Some forecasters envisioned a world in which hi-fi consumers moved to electrostatic loudspeakers.

They only did not really make it really into that future apart from a niche audience. And pairing the sansui au505 with an electrostatic loudspeaker would have been a quite a riskful and perhaps terrible choice.

So, this and the CD that followed as a prototype. The mid 70s were transitional into a new age, maybe among the biggest turning points in audio history..

 

[RexrothPigeon]

Especially because no one really knew what path hifi would go in general.

The only path hifi can go is towards higher fidelity, that is, greater faithfulness to the source recordings, which means a path towards cleaner, more neutral reproduction.

Of course home audio gear can take other paths, but it's not hifi if it does so, it's an effects box.

 

[pinger]

It would be easy money for anyone here to select the au505 in a double blind test compared to a more revealing one. I would maybe not be able to pick it when it would be compared to another random warm voiced amplifier. Altough I perhaps would at lower gain levels and its high "presence" level.

Will leave out the lighter au101 in this claim as it is best with its loudness contour on as mentioned, and that would be cheating if no aides would be virtually allowed

If its so easy why has there never been a documented double blind test proving that differences are audible and can be identified? Also dont you think if it could be proven manufacturers would use it to sell their products? The fact that they dont tells you all you need to know. I'm speaking of course about SS amps

 

[AJM1981]

The only path hifi can go is towards higher fidelity, that is, greater faithfulness to the source recordings, which means a path towards cleaner, more neutral reproduction.

Of course home audio gear can take other paths, but it's not hifi if it does so, it's an effects box.

The part you quoted was about electrostatic loudspeakers in the 70s, the future that was projected on them (once it was like the next best thing, Quad released one of the first consumer friendly sets) and their higher damping factor requirements in order not to literally destroy the gear. Electrostatic loudspeakers were once a possible new future, but they did not take anything near the largest market share.