Hopkins' System

[hopkins]

I posted this recording and someone posted a comment on another forum:

"...energy reserves are not good enough, in the DAC, which also serves as the amplifier; solid, long drawn out bass notes are draining the power supplies, and the SQ falters. If the train of notes doesn't tax those energy reserves, then the circuitry can maintain good operation, and the replay works well."

This is an example of wrongfully applying "knowledge" of conventional amplifiers to this product. The power supply is not "drained" in the powerDAC. It remains constant. The recording was made at roughly 75% of the maximum volume, so there is plenty of headroom.

What bothers the author of these comments, I don't know, but the explanation of the cause is incorrect. I suspect that the speakers, working as full-range, could struggle and distort way before the amplification... The room acoustics are also far from ideal especially in the bass department (room modes on the left speaker).

 

[morricab]

I posted this recording and someone posted a comment on another forum:

"...energy reserves are not good enough, in the DAC, which also serves as the amplifier; solid, long drawn out bass notes are draining the power supplies, and the SQ falters. If the train of notes doesn't tax those energy reserves, then the circuitry can maintain good operation, and the replay works well."

This is an example of wrongfully applying "knowledge" of conventional amplifiers to this product. The power supply is not "drained" in the powerDAC. It remains constant. The recording was made at roughly 75% of the maximum volume, so there is plenty of headroom.

What bothers the author of these comments, I don't know, but the explanation of the cause is incorrect. I suspect that the speakers, working as full-range, could struggle and distort way before the amplification... The room acoustics are also far from ideal especially in the bass department (room modes on the left speaker).

Sensitivity of this speaker would suggest a good SET or single ended transistor (FirstWatt for example) would make good sound. Have you tried?

 

[hopkins]

Sensitivity of this speaker would suggest a good SET or single ended transistor (FirstWatt for example) would make good sound. Have you tried?

I don't have one, and honestly don't see the need for one either. The low level of distortion of the PowerDAC-SX is really impressive. Using separate amp + preamp + DAC + interconnects is not something I want to go back to.

I would be curious for others who do use low power SET amps to try this PowerDAC-SX, but that may be wishful thinking!

If I can find someone with such a setup, in or around Paris, I would be glad to compare on their speakers in their room.

With 16 watt maximum output per channel, there are lots of speakers that can be easily driven by this amp...

 

[hopkins]

Here is the first minute of that track recorded from a single speaker with the mic (Tascam DR-40X build-in) placed a little closer to the speaker. I stopped the recording when a helicopter approached my neighorhood!

https://storage.googleapis.com/cloudplayer/samples/Pogorelich.wav

I don't know what others could conclude from this, but I don't hear any issues with "power" or "energy reserves". This is with the powerDAC-SX dialed at a volume level of 20 out of 25. I cannot play it louder in my flat...

 

[hopkins]

Back to music I actually enjoy...

Ray Nance!

The original recording quality is far from perfect, but it swings! Fascinating performance by one of my favorite jazz musicians.

 

[hopkins]

Lena Horne!

Her last album, recorded in 1997, is a gem.

 

[hopkins]

What's not to love about Carman McRae singing Monk?

Saxophone solo by Clifford Jordan

 

[hopkins]

Clifford Brown

I like to keep the speakers wide apart. On these mono recordings, the sound is right in the center as if it was coming out of the amp ( my girlfriend thought it was!)

It is not perfect from an audiophile standpoint, but it sure is fun

Next step is to rewire my speakers properly. I will also be testing some tweeters for them, probably in a couple weeks.

 

[hopkins]

One of the striking features of this new powerDAC-SX is the clarity and "presence" of the various instruments. This gives a live quality to the sound, but it also always sounds relaxed and effortless. I've never heard digital sound this good - and the quasi-comical aspect is that a measly raspberryPi is all you need to achieve these results.

An audiophile friend came over and was thoroughly impressed (we did not even bother to compare with the previous model, which he heard several times in my home).

Unfortunately, low quality videos really don't do the system justice. My better microphones are damaged, and the portable Tascam DR-40X recorder I have is only marginally better. I'll try to get my hands on good quality equipment, from an acquaintance, as I would like to share what I hear...

In the meantime, here is another phone video of a song which impressed me (and which I like). The system creates a tapestry of sounds. Maybe hard to perceive from the video...these cheap microphones can't take the heat

Make sure you listen to the break starting at 5:30...

Video is available in 4K quality on YouTube. Not sure how much that affects the sound.

 

[chet atkins]

One of the striking features of this new powerDAC-SX is the clarity and "presence" of the various instruments. This gives a live quality to the sound, but it also always sounds relaxed and effortless. I've never heard digital sound this good - and the quasi-comical aspect is that a measly raspberryPi is all you need to achieve these results.

An audiophile friend came over and was thoroughly impressed (we did not even bother to compare with the previous model, which he heard several times in my home).

Unfortunately, low quality videos really don't do the system justice. My better microphones are damaged, and the portable Tascam DR-40X recorder I have is only marginally better. I'll try to get my hands on good quality equipment, from an acquaintance, as I would like to share what I hear...

In the meantime, here is another phone video of a song which impressed me (and which I like). The system creates a tapestry of sounds. Maybe hard to perceive from the video...these cheap microphones can't take the heat

Make sure you listen to the break starting at 5:30...

Video is available in 4K quality on YouTube. Not sure how much that affects the sound.

How much $$$ for the DAC

 

[hopkins]

How much $$$ for the DAC

The model I use is 3450€ (excl VAT). They have other models which rely on the same technology but with limited power output and therefore meant to be used with external amplification. How these perform, I don't know - I assume the answer will depend on the quality of the amp you pair them with.

Shop – ECdesigns

www.ecdesigns.nl

They will be on sale shortly. As a long-time customer they were kind enough to send me a model to test, and I will be purchasing it.

 

[hopkins]

Testing low level nearfield listening, late at night.

Speaker placement has to be fine tuned...

 

[hopkins]

One of the "tangible" and surprising aspects of this amp is that you essentially get the same quality at very low or very high volume. Of course, at high volume the music is more impactful and fleshed-out, but the sound is essentially the same at low volume, just "miniaturized". This is not something I have experienced before.

The videos I posted above are low quality, and I will try to post some others. With my Tascam recorder, I pick up more ambient noise, so it is hard to make a good recording at low listening level.

 

[hopkins]

Dropped by the Paris Audio Video show this morning. Listening conditions are always poor, but I had a front row seat for this one:



A good reminder of some of the things I am missing with my speakers, but also of the reasons why I like them!

Speakers are advertised as 98dB @ 1m @ 2.83V.

Could not help wondering if the sound would be any different if all these (expensive) components sitting between the speakers were to be replaced by the small "integrated" amp I am using.

I am testing the addition of tweeters to my open baffles, and like the results. I took the opportunity to revisit the speaker placement I have been using for a few months, and am finding I can flatten out the response of the speakers in different configurations (speaker position and seating position). Work in progress...

 

[hopkins]

Jan Evensmo has published new "solographies" - one of the pianist Hugh Lawson that contains references to a lot of interesting music: https://www.jazzarcheology.com/hugh-lawson/

You can subscribe to his newsletter and receive notifications for his new material. I always look forward to reading them (and listening to the music he talks about).

 

[hopkins]

Results of a different speaker placement in my room - this frequency response curve (psychoacoustic smoothing) shows variations of (generally less than) +/- 3db between 60hz and 8kHz, and it sounds good (better) to my ears. Bass response and high frequency response will be improved...

 

[morricab]

Results of a different speaker placement in my room - this frequency response curve (psychoacoustic smoothing) shows variations of (generally less than) +/- 3db between 60hz and 8kHz, and it sounds good (better) to my ears. Bass response and high frequency response will be improved...

View attachment 118570

Bass could use a boost but HF not as it will sound too bright in room.

 

[hopkins]

Bass could use a boost but HF not as it will sound too bright in room.

This was actually taken with added tweeters, but I need to fine tune their placement on the baffle (and tilt). Without the tweeters, the HF response is more variable. Concerning the bass, I would be curious to try subwoofers at some point, but I may also play around with baffle wings. The overall response is very similar on both speakers, as they are now placed facing the length of the room, in a more symmetrical setup. With my speakers facing the width, the response of the left speaker (towards the side wall) was very different from my right speakers, and the bass response on that speaker was not good - but the added distance between the two gave a very nice soundstage which I appreciated. With the speakers closer together, my seating position is much closer, and I can play music more softly. Still working on all this...

 

[morricab]

This was actually taken with added tweeters, but I need to fine tune their placement on the baffle (and tilt). Without the tweeters, the HF response is more variable. Concerning the bass, I would be curious to try subwoofers at some point, but I may also play around with baffle wings. The overall response is very similar on both speakers, as they are now placed facing the length of the room, in a more symmetrical setup. With my speakers facing the width, the response of the left speaker (towards the side wall) was very different from my right speakers, and the bass response on that speaker was not good - but the added distance between the two gave a very nice soundstage which I appreciated. With the speakers closer together, my seating position is much closer, and I can play music more softly. Still working on all this...

Your amp is likely somewhat over damped for full range drivers in an open baffle configuration…it might necessitate subs…then think dipole subs…or you will have blending difficulty.

 

[hopkins]

Your amp is likely somewhat over damped for full range drivers in an open baffle configuration…it might necessitate subs…then think dipole subs…or you will have blending difficulty.

I don't think the amp is the issue. The manufacturer used these baffles with a number of other amps (solid state, tube..). Bass response is limited with the Tang Band, my baffles are probably a little too narrow, and the room does not help. But yes, dipole subs could ultimately blend well. I am in no hurry, however.