Author Topic: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.  (Read 11561 times)

Offline HAL

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The Orchard Audio BOSC amps have arrived to demo with The Monoliths speaker system.  These will be the BG NEO10 driver amp in the system for trials.
 
Made a custom set of 2' speaker cables for direct connection to the driver terminals.

Balanced inputs on the amps, so easy connection to the dspMusik 2x8 digital crossover. 

A slight change in Parasound A23 tweeter amp levels to match the BOSC amp gain.  Very simple change to the crossover.

Offline mdconnelly

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #1 on: September 25, 2019, 10:53:35 AM »
Looking forward to hearing what you think of them!     Leo's Kickstarter campaign will expire on Oct 6th and I really hope it succeeds.    :thumb:

Offline HAL

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #2 on: September 25, 2019, 06:04:05 PM »
Will keep everyone posted as I get listening time.

Everything is connected.  Here is one BOSC amp directly connected to the BG NEO10 planar driver.   Next is updating the gain settings in the dspMusik 2x8 crossover block diagram.

Offline orchardaudio

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #3 on: September 25, 2019, 06:26:25 PM »
Looking forward to your findings.

Offline Guy 13

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Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #4 on: September 25, 2019, 06:33:34 PM »
Hi all.
I am curious to know how they sound,
those units are so little...
In size of course.

Guy 13
Grace Digital Mondo RIT
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Offline tmazz

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #5 on: September 25, 2019, 11:29:40 PM »
Leo was the featured guest at an AudioSyndrome meeting at my house about 18 months ago where he demonstrated his first generation amp, DAC and streamer (the Apple series) for the club. Very nice sounding gear. His streamer/DAC combo impressed even our most die hard vinyl guy, who said he thought was "engaging." While this might sound like somewhat faint praise the background story to this is that this was the first time I had ever heard him say something nice about any piece of digital equipment.

And from everything I have heard, the new series of gear sounds even better.

Definitely worth consideration on sound alone, but even more so if space is a consideration for you, as Leo gets great sound out of gear that has a very small footprint.
Remember, it's all about the music........

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• VPI HW-19 Mk IV/SDS/SME IV/Soundsmith Carmen Mk II ES
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Offline orchardaudio

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #6 on: September 26, 2019, 05:03:11 AM »
Leo was the featured guest at an AudioSyndrome meeting at my house about 18 months ago where he demonstrated his first generation amp, DAC and streamer (the Apple series) for the club. Very nice sounding gear. His streamer/DAC combo impressed even our most die hard vinyl guy, who said he thought was "engaging." While this might sound like somewhat faint praise the background story to this is that this was the first time I had ever heard him say something nice about any piece of digital equipment.

And from everything I have heard, the new series of gear sounds even better.

Definitely worth consideration on sound alone, but even more so if space is a consideration for you, as Leo gets great sound out of gear that has a very small footprint.

Wow I can't believe it's been that long...

Offline HAL

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #7 on: September 28, 2019, 12:56:32 PM »
The BOSC amps are up and running in The Monoliths system.  The are powering the BG NEO10 mids, so a very sensitive frequency range of 200Hz to 2.6KHz. 

Checked DC offset since both the BOSC amps and dspMusik 2x8 are DC coupled.  Highest channel DC offset was 24mVDC, very similar to other amps here.  Very good for fully DC coupled!

First listening with everything from start is that they are very good.  The rest of system will be coming up to temperature and more listening once it is stabilized.  Class A/B amps take awhile here as usual. 

More as listening continues.

Offline HAL

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #8 on: September 28, 2019, 07:10:42 PM »
From the first listening, the BOSC amps are much quieter than the A23's.   Background noise level is below hearing from the mids where before there was a background noise level.  The BG NEO10 is 92dB/1w/m sensitivity, so most amps have a residual noise level.  Not with these.

The lower gain of the amps helps to use more of the DAC's output voltage range compared to the higher gain amps.   Gives better overall SNR for the system.

Nothing stands out as wrong.  Everything is clean and distinct without being analytical.  Very nice with big orchestral pieces or complex rock music.  Acoustic instruments sound very realistic.  There is an immediacy that having direct connection with very short speaker cables makes possible.  Transient edges have excellent attack and nice decay. 

Very happy with the amps in the system so far and lots of listening to do.

Offline orchardaudio

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #9 on: September 29, 2019, 04:54:11 AM »
Background noise level is below hearing from the mids where before there was a background noise level.

The residual noise of the amp itself is only 32uV, then whatever noise your DAC makes will be added to the 32uV multiplied by the Amp's gain. Since the gain of the amp is low relative to others the overall output noise will also be very low and should be completely inaudible.

Offline Guy 13

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #10 on: September 29, 2019, 05:17:54 AM »
Background noise level is below hearing from the mids where before there was a background noise level.

The residual noise of the amp itself is only 32uV, then whatever noise your DAC makes will be added to the 32uV multiplied by the Amp's gain. Since the gain of the amp is low relative to others the overall output noise will also be very low and should be completely inaudible.

Hi.
Some amplifier manufacturers rate their s-n ratio in db,
I saw -90db on a tube amplifier, how does that compare to your 32uV ?
I know db doesn't mean much if you don't state other parameters.

Guy 13
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Offline HAL

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #11 on: September 29, 2019, 06:00:24 AM »
Background noise level is below hearing from the mids where before there was a background noise level.

The residual noise of the amp itself is only 32uV, then whatever noise your DAC makes will be added to the 32uV multiplied by the Amp's gain. Since the gain of the amp is low relative to others the overall output noise will also be very low and should be completely inaudible.

Hi.
Some amplifier manufacturers rate their s-n ratio in db,
I saw -90db on a tube amplifier, how does that compare to your 32uV ?
I know db doesn't mean much if you don't state other parameters.

Guy 13

If my math is correct the noise floor is -132dBV in a 1Hz bandwidth (corrected for 20KHz bandwidth measurement) from a 32uVrms noise floor.  That is not SNR as stated. 

If I spotted it correctly the SNR is 120dB.
« Last Edit: September 29, 2019, 06:01:55 AM by HAL »

Offline orchardaudio

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #12 on: September 29, 2019, 06:12:25 AM »
SNR is 121dB (a-weighted) or 118dB with no weighting. The 32uV number is based on the 121dB measurement.

dB is just a ratio between two numbers. The amp's nominal output voltage is 34.6Vrms, since the noise is 32uV. The SNR is 121dB.

Every 20 dB is equivalent to a factor of 10. So 120dB is 1,000,000:1.

With 121dB it is a little better than a million to 1.

Offline Guy 13

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #13 on: September 29, 2019, 01:16:00 PM »
SNR is 121dB (a-weighted) or 118dB with no weighting. The 32uV number is based on the 121dB measurement.

dB is just a ratio between two numbers. The amp's nominal output voltage is 34.6Vrms, since the noise is 32uV. The SNR is 121dB.

Every 20 dB is equivalent to a factor of 10. So 120dB is 1,000,000:1.

With 121dB it is a little better than a million to 1.

Thanks for the information.

Guy 13
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Offline HAL

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Re: Orchard Audio BOSC amps here to demo with The Monoliths Speaker System.
« Reply #14 on: October 01, 2019, 08:15:29 PM »
Hope people go and support Leo's Kickstarter campaign.  Only a few more days left to sign up.

Very happy with the BOSC amp listening trials and have put in for two pairs. 

Have a demo for some friends on Thursday and then they go back to Leo.  Hope the next person enjoys them as much as I do.