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Author Topic: My experience with s3x as a loudspeaker amp  (Read 373 times)

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Offline ccmccull

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My experience with s3x as a loudspeaker amp
« on: March 07, 2022, 09:04:36 AM »
Hi all,

I’ve been living with my s3x amp for a few months now, and I wanted to share a wild experience I’ve recently had with it.

I bought the s3x kit as a headphone amp for my sensitive Grados and it’s fantastic with them as expected. But a couple of weeks ago, I thought I’d try it out on loudspeakers. I run fairly low sensitivity Spendor S3/5R2’s (84dB/W/m), so I wasn’t really expecting much from this 2W amp compared to my 100W Schiit Vidar. More specifically, what I expected was that the s3x might be more intimate and “musical” (whatever that means) on acoustic, folk, and small ensemble jazz, but that it would fall down on higher dynamic range orchestral, funk, and rock. Boy was I wrong. I’ve done a bunch of A/B testing of these two amps and I have yet to find a track that the Vidar out-performs the s3x. Sometimes it’s close to a draw, but often the s3x is noticeably superior. I’ll share more details on what I mean below in some listening notes on specific tracks.

But first, the setup for the comparison: I used a rasberrypi4 ropieee Roon endpoint streaming Qobuz, a schiit modius DAC into a moreplay preamp, whose two RCA outputs fed the two power amps. Now, my speaker setup is a little weird. I run stereo SVS-SB1000 subs in parallel with the Spendor’s speaker level cables. I run the SVS cross-overs at their highest setting (~180 hz), and I set their volume very low, in order to just barely fill in the mid and low bass that’s somewhat lacking from the small Spendors. The subs sit on 3 foot speaker stands with the spendors on top of the subs. It’s an ugly setup, but it sounds great. The room is 14x17, moderately acoustically treated, and I sit around 9 feet from each speaker. For these tests I listened at a punchy but not deafening volume.

The A/B test wasn’t perfect and certainly wasn’t blinded. I didn’t use a switcher box, I just moved the banana plugs between the Vidar and the s3x. I marked the Moreplay volume pot in two spots with masking tape at levels which pretty accurately equalized the volume on the Vidar and S3x. I used a test tone and spl meter to calibrate the volumes. I set the s3x volume pot to ~70%.

Here are some listening notes. This is the first time I’ve ever written down my thoughts on listening to anything, so I probably don’t use all the right buzz words. Go easy on me!

First up, Brandi Carlisle, In these Silent Days, You and Me on the Rock: the placement of the two acoustic guitars are more focussed on the s3x. On the Vidar, they sound like they’re coming directly from the speakers. Also, the background singers are better separated from Brandi on s3x. You get a clear sense they’re standing behind Brandi. On the Vidar, the presentation is flatter.

Sarah Jarosz, Build Me up from Bones, title track: On s3x amp, Sarah’s voice is more nuanced, less high-mid forward. The vidar renders her voice slightly more stridently. But the cello and violin solo parts near the end are where the s3x shines. It reveals the bow pressure and speed like the Vidar can’t. (I’m a cellist so I love this!) They sound like they are in the room with you. The vidar separates them correctly left to right, but they don’t sound like realized instruments in the room. Again I think it’s the soundstage depth behind the speakers that makes the difference.

Daft Punk, Random Access Memories, Give Life Back to Music: The s3x amp is more alive, the tinkly chimes in the center right are crystal clear, the placement of the two voices are more clearly top left vs. bottom right. (How do they do that with a stereo recording?!) The s3x also has a wider soundstage which extends clearly outside the speakers, e.g. the handclaps. The vidar soundstage is more constrained between the speakers.

Peter Gabriel, Plays Live, Rhythm of the Heat: The general sense of spaciousness of the concert venue is superior on the s3x. This again comes from the soundstage depth and imaging outside the speakers. The Vidar is flatter and between the speakers

Alabama Shakes, Sound and Color, Gimme all your Love. This is a track where I was really expecting the Vidar to win, since it’s such a high dynamic range recording. Not true. The overall dynamics are actually stronger on the s3x. When the kick drum starts up again in the 2nd half of the song, you feel it in your guts. The vidar is no slouch, but it doesn’t make you tense up like the s3x does. Beyond this, there is a whole different level of detail on the s3x. You can almost feel the drumsticks touching the high-hat and ride cymbal. Particularly on the high-hat, the Vidar makes all the touches sound the same.  At 1:05 when the singer sings the a-huh-a-huh-a-huh part, you can almost see her jaw moving.

Lady Gaga & Tony Bennett, Love For Sale, I’ve got you Under my Skin: I don’t think this is a particularly well recorded album and it’s interesting that the amps are much more closely matched in this setting. The instrument imaging isn’t very good on this recording. But I did notice that the s3x amp transparently reveals all the weird intonations and head bobs away from the mic Lady gaga does, e.g. on the early line “you’re so deep in my heart”. The Vidar represents her voice more flatly. The rim shots are more prominent on the s3x. The walking base line is slightly muddier on the Vidar.

Orchestre symphonique de Montreal (Charles Dutoit), Holst The Planets, Uranus the Magician: The difference here is the overall sense of the concert hall. With the s3x amp, it’s like you’re in the mezzanine front row and you can picture the whole stage in front of you. Every instrument section is perfectly placed on the stage. The vidar just doesn’t do this - it sounds more “stereo”. At 1:30, when the strings and french horns play in unison, you can clearly distinguish the violins to the bottom left, the horns to the center right. At 3:44, when the timpani starts rocking, you can almost see the mallets flying!

I hope this was interesting for someone to read, maybe as you’re considering whether to buy a s3x kit. Overall, I was blown away by how much kick and detail this little 2W amp can deal even on supposedly low sensitivity speakers! None of this post is meant to disparage the Vidar. It’s a truly great amp. But I will probably keep it disconnected in this setup from now on, in favor of the s3x.


« Last Edit: March 07, 2022, 09:29:00 AM by ccmccull »
Colin
{Ortofon 2m Blue > U-Turn Orbit > Eros 2} & {Roon Ropieee RPi4 > hifiberry-digi2-pro > Modius} > Moreplay > S.E.X. > {{Spendor_S3/5r2 & SVS_SB-1000 (x3)} & Grado_sr325x}

Offline Paul Birkeland

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Re: My experience with s3x as a loudspeaker amp
« Reply #1 on: March 07, 2022, 09:13:01 AM »
I applaud you for giving this setup a shot!  How loudly did you find that you were listening?
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline ccmccull

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Re: My experience with s3x as a loudspeaker amp
« Reply #2 on: March 07, 2022, 09:22:57 AM »
Subjectively, it was loud, i.e. I wouldn't want to listen any louder. Objectively I'm not sure how to answer (OK I shouldn't have said I used an SPL meter in my original post, I used the android app Spectroid for the volume calibration, and my ears...) On that app, background is ~ -130 db, and the loud parts were ~ -60 db. So 70 db I guess?

I'll also say that I can definitely turn up the s3x much louder without distortion.


Colin
{Ortofon 2m Blue > U-Turn Orbit > Eros 2} & {Roon Ropieee RPi4 > hifiberry-digi2-pro > Modius} > Moreplay > S.E.X. > {{Spendor_S3/5r2 & SVS_SB-1000 (x3)} & Grado_sr325x}

Offline ccmccull

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Re: My experience with s3x as a loudspeaker amp
« Reply #3 on: March 07, 2022, 09:48:32 AM »
duh. I forgot I have an SPL meter in Rew. (with umik calibrated mic). LZFmax 72 dB, LZpeak 83 dB.
Colin
{Ortofon 2m Blue > U-Turn Orbit > Eros 2} & {Roon Ropieee RPi4 > hifiberry-digi2-pro > Modius} > Moreplay > S.E.X. > {{Spendor_S3/5r2 & SVS_SB-1000 (x3)} & Grado_sr325x}

Offline Doc B.

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Re: My experience with s3x as a loudspeaker amp
« Reply #4 on: March 07, 2022, 10:04:06 AM »
Thank you for the kind review! According to your meter you aren't even pushing a full watt into your speakers. I think one lesson here is how well adding a powered sub to small low powered speakers can work. I do that in my home theater, which uses a couple of 3.5W Stereomours for front and center and a S.E.X. amp for surrounds. I run two powered subs, one under the screen and one right behind our seats (the sandworm scenes in the new Dune are bladder shakers) and the other speakers sound clear and uncompressed even in sound effect heavy scenes.
Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline ccmccull

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Re: My experience with s3x as a loudspeaker amp
« Reply #5 on: March 07, 2022, 10:32:46 AM »
Happy to opine Doc!

Would you please educate me on the math behind your 1 watt statement? FYI the mic was at listening position at  around 9 feet from the speakers.
Colin
{Ortofon 2m Blue > U-Turn Orbit > Eros 2} & {Roon Ropieee RPi4 > hifiberry-digi2-pro > Modius} > Moreplay > S.E.X. > {{Spendor_S3/5r2 & SVS_SB-1000 (x3)} & Grado_sr325x}

Offline Doc B.

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Re: My experience with s3x as a loudspeaker amp
« Reply #6 on: March 07, 2022, 10:57:49 AM »
Speakers are 84dB @1W @1M. You can pretty much ignore there being any level dropoff using pink noise or other wide band signal with some bass content within the reverberant field (i.e. the part of the room where reflected sound dominates), so your meter reading at 3M is pretty similar to what it would be at 1M. If 84dB speakers are running at 83dB peak that means the amp is pushing slightly less than 1W peak into them. That is presuming you are only running one channel for the measurement. If both speakers are running when you measure 83dB each speaker is using only half the power, hence each amp channel is putting out half as much power.

This of course is different than measuring frequency response, where you would see some level differences in the HF portion of the response as the mic position gets closer to the speaker.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline ccmccull

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Re: My experience with s3x as a loudspeaker amp
« Reply #7 on: March 07, 2022, 11:14:51 AM »
Great explanation thanks!
Colin
{Ortofon 2m Blue > U-Turn Orbit > Eros 2} & {Roon Ropieee RPi4 > hifiberry-digi2-pro > Modius} > Moreplay > S.E.X. > {{Spendor_S3/5r2 & SVS_SB-1000 (x3)} & Grado_sr325x}

Offline tsingle999

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Re: My experience with s3x as a loudspeaker amp
« Reply #8 on: March 08, 2022, 01:58:00 PM »
Great review and right on the money in terms of my experience with that amp! I have had people's jaw drop when comparing it to a solid state amp. It is one of the best kept secrets in audio! The other BH I feel is a audio secret is the Nectar headphones with the BH stat electrostatic amp.
SGS iTransporter with Qobuz to Roon to Optical Rendu to BH DAC (Battery) to BeePre to 300b(ehemoths) to Jagers.
Bottlehead Stat headphone amp with Brick DAC