Messages

Note: The following is a mailing list posting by John Dunlavy, a well known audio designer. I stashed a copy of this posting because I wanted to cite it in my stereo equipment page, and at the time there were no good repository of the mailing list or usenet articles that was accessible via a stable URL. I would suggest you check out audio postings by dunlavy for even more information.

96.11.5 - Cable Nonsense - Long.pdf

A white paper on the performance attributes of various loudspeaker designs.

CONES, PLANARS & DOMES.pdf

LISTENING ROOM CONSIDERATIONS.pdf

Various Measurements used by Dunlavy

Step response.pdf

Competitor Impulse Responses

BKn competitor impulses YUK.pdf 

Click here to view John Dunlavy's CV

https://audiokarma.org/forums/index.php?threads/dunlavy-audio-labs-archive-from-the-mind-of-a-legend.769216/

https://forum.polkaudio.com/discussion/65807/worlds-most-accurate-loudspeaker/p2

https://www.audiosciencereview.com/forum/index.php?threads/the-dunlavy-interview-1996.14646/

https://www.diyaudio.com/community/threads/designing-creating-a-dunlavy-type-speaker-from-the-ground-up.368244/

https://tmraudio.com/blog/duntech-to-dunlavy-legend-with-a-colorado-connection/



Loudspeaker Measurements

Quality Control Program at DAL

DAL's listening rooms

Tech Talk

Since our original facebook page was hacked we were never able to recover the ability to login no matter what we did so we gave up on it. Since then facebook has upgraded its security with 2FA so it is harder for hackers to do this.

Anyway, rather than keep hitting our heads against a brickwall trying to recover the unrecoverable I have created a new facebook page at https://www.facebook.com/NewAnalogPrecision

And for those playing along at home the old facebook page is still accessible

https://www.facebook.com/AnalogPrecision/

Hi David,
Any plans for lower cost modular option ?

I'm building new pair of loudspekaers, active witn hypex mcXXXmp amplifiers.

For me, it would be great if I could place DSP inside loudspeaker cabinet.
So I would need two DSP boards, one for left and one for right channel

Hypex have some 3 way DSP solution (FA series) but thay are not high end as yours.

Olso, it would be great to have some option for presets.
So that we dom't have to use audioweaver every time we would like to "hear" or compare two diferent setings...not to mention licence for it...

Any way, I know how much work and time you invest into those, thay are high end products but it would be great to hove something that is more affordable for "normal" diyer.

I think that now days active sistems are great solition as we have more and more good and low cost amplofiers and drivers but we are limited with DSP solution.

I belive that you know how to make good product, and maybe to produce raedy made main DSP boards with kit option (PCB with or without parts) for diy (power supply and output boards or so).

Sorry for bad english

Best regards
Josip

Hi Josip

Yes I have plans for a very high cost option for an international speaker builder but not a low cost one at the moment.

Having said that, at one stage I did contemplate on moving manufacturing to China to take advantage of economies of scale and locality to produce a much lower cost Preamp but because of covid the plans were scuttled

I understand your need to switch different Audioweaver configs and many others have inquired about this ability but am not sure if DSP Concepts has implemented this ability yet.

It might be worth revisiting the DSP board offering again but have a single board solution where all of the connectors are mounted on the same board rather than scattered across multiple daughter boards but with a greatly reduced feature set.

Regards
David

Looks like an excellent improvement! Will there be any other changes to the card?

Mainly the ADC is the biggest upgrade otherwise everything else is the same

cheers
david

On the drawing board is our next Revision(D) of the main DSP board which now features an upgraded ADC (Analog to Digital Converter) from the existing 24 bit TI part to the Flagship ES9822PRO 32 bit ESSTech ADC. The ES9822PRO ADC features ESS proprietary Hyperstream II ADC Architecture, which delivers unprecedented conversion performance and yields top notch specs of 124 dB DNR and -117 dB THD+Noise. The ES9822PRO has an Ultra-Low Noise Floor Bandwidth of 200kHz. This bandwidth is up to 10 times wider than the competition, enabling higher resolution at higher sampling rates and along with the ESS 8-channel ES9038PRO Sabre DAC and our own onboard FEMTO master clock providing infinitesimal jitter we are certain this should satisfy the most fastidious analog aficionados who are into vinyl or reel-to-reel playback ! 

Also we use a filter to filter out any ultrasonic noise from class-D amps.

https://analog-precision.com/forum/performance-and-measurements-12/measurement-equipment-14/

Thank you for sharing. The measurements we did was THD + Noise so slightly different to your THD only measurements. Either way these amps are very good

regards
David

[These preamps operate in perfect sync with each other and the master preamp controls the volume, balance and muting on all of the other slave preamps in perfect unison.]

We had a recent enquiry by someone who wanted us to build a preamp with 16 outputs ! But what if someone asked us to build a 24 or 32 or even a 48 channel or more hi-end stereo pre-amp and our preamp only had 8 outputs? Fear not with the external Link-Port on both the UP2 and UPP you can chain as many preamps together as you need to get as many outputs as you need with no loss of information or performance ! Why would you need such high channel count ? One application comes to mind and that is a phased array loudspeaker or wave shaped loudspeaker with many independent driver channels such as the B&O kii audio etc or even a multiple active speaker that are all controlled by the same pre-amp.

By itself the Ultimate Preamp 2/+ has 8 outputs plus an optional digital output to drive an external stereo DAC bringing the total output count to 10 channels which is still far short of 48 channels. However, the main DSP board used in the preamp has provision for connecting multiple DSP boards as a master and many slave arrangement in the one chassis using the on-board Link-Port connector.

However, from a practical point of view this would require a redesign of the enclosure and power supply to handle multiple boards and output connectors which is just not practical at this point in time. We just needed to extend this facility outside the chassis so that we could link multiple preamps in 8-output clusters and they all needed to sync perfectly together when changing things like the volume, balance, mute etc because you don’t want to have to adjust each preamp’s volume control every time you need to adjust the volume.

Because this was a planned feature for the UP2 and UPP we needed to make sure it worked perfectly before we started shipping the preamps so whilst we still have all of the preamps in our lab undergoing testing before we ship them what better time to test out this feature which is why we have spent the last week updating the firmware and hardware to make sure it all works as advertised. As an example we took 6 preamps and chained them all together in a one-master five-slave system to give a total channel count of 48 channels !. We also loaded the simple Audioweaver pass through example which feeds a stereo signal directly to all 8 channels but this could be any design of your choosing. It also helps us test the HDMI I2S input and the Link-Port HDMI output ports on the preamp at the same time 😉

The bottom preamp is assigned the master preamp and the top five preamps are assigned slave preamps connected in daisy chain fashion using HDMI cables.

These preamps operate in perfect sync with each other and the master preamp controls the volume, balance and muting on all of the other slave preamps in perfect unison.



48 channel VU meter operating in real time !



Muting works across all preamps as well.



A 48 channel Preamp playing vinyl

Since we have an interest in using some of the products from Purifi Audio in a new project this article makes for interesting reading

https://www.hifishark.com/article/visiting-purifi-audio

The Latest test results and measurements from our Lab show the Ultimate-Preamplifer 2/+ meets or exceeds its design objectives by a huge margin ! Click here to view more.