Hopkins' System

[hopkins]

Two years ago I first assembled these open baffle speakers and was amazed by the sound (in my cramped old flat, with the speakers positioned too close to each other, and inverted):

I still have vivid memories of the first time I played them! At the time I was using Davis Courbet speakers (sold since), which are nice little speakers, but nowhere near offering the transparency of the open baffles.

The sound still amazes me today (it actually sounds better than on a video, as can be expected) but I also still have issues with room acoustics.

Those two diffusers shown in the video don't really do anything, they are not deep enough and don't cover a large enough surface.

Since I switched (for practical reasons) from placing the speakers along the length to the width of the room I no longer have the issue of sitting against a wall (the room is 11 meters deep, which is nice), but I now I need to figure out how to deal with front wall reflections. I cannot move the speakers further away from that front wall.

I was considering putting decorative absorption panels (and moving the current panels I have hanging there to another wall of my living room)

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I am now wondering whether diffusion may be a better option? Diffusion panels are unfortunately not visually very pleasing...

I am afraid the bass traps I have in the corners behind the speakers are not sufficient either, but that is less of an issue for me.

That being said, I love the sound, but I just feel things are not optimal.

---

I was able to test AMT tweeters someone lend me and they are really beneficial, even if their sensitivity is a little low compared to the 4 Tang Band drivers. Wired with a single capacitor in series (the TB drivers are kept filterless) they add some air and sound very refined. I'm sold on that.

 

[hopkins]

The supplier of these nice panels I mentioned in my previous post can offer them with absorption or diffusion. I cannot test diffusion, but I do have a number of absorption panels that I placed on that front wall for testing purposes. To my ears, it is more pleasant with absorption than without, and I feel more relaxed while listening. Perhaps diffusion would provide the same benefits, with less damping. Difficult choice... My room being fairly reverberant (concrete walls, low ceiling), I am leaning towards absorption on that wall.

As we get older our hearing deteriorates and I believe that our ability to discriminate between direct and reflected sound may not be as good as before...

I also adjusted the speaker placement and listening position slightly to form an equilateral triangle (speakers are roughly 2.15 meters apart) and I feel this provides more focus. With mono tracks, I get a perfectly centered image. Two speakers will never offer the "definition" of a single speaker, but the results are acceptable.

Because microphones don't mimic our ears, and phone videos are not the best quality, thes subtle differences may not be so obvious on videos. I posted a few other comparisons with different tracks on my channel, for anyone interested.

 

[hopkins]

I will try to record with my Tascam recorder, as I think those subtle differences in acoustics cannot really be heard with a phone recording.

I am always curious to hear how things sound with videos/recordings, with the hope that differences are obvious (which is not always the case), and if so that it can help me choose between different configurations. Recordings can be useful to get a more "objective" viewpoint.

 

[hopkins]

A well known track (Illinois Jacquet - Harlem Nocturne). Big sound from Jacquet's saxophone. Nice muted trumpet from Roy Eldridge as well. The track is "quasi mono".

Playing around with speaker placement. Next step will be to tame down the room a little.

 

[hopkins]

I found it interesting to compare that (mono) track on my single Altec speaker:

I can't be objective about these videos, but I can certainly explain how I feel listening to these speakers in my living room. The sound from my open baffle speakers is more "impressive", but with my Altec speaker, I feel like I get drawn into the music more easily and more deeply. On that track, the trumpet solo (from 2:11) was particularly striking in terms of contrast and dynamics. It suits Roy Eldridge (and the rhythm section) well. The mood of the track is really felt "fully" and the sound has a hypnotic quality.

The difference between the two speakers is a little like the difference between riding a single speed versus a multiple speed bicycle. A single-speed gives you the impression of a more "direct" transfer of the movements and force of your body into the bicycle and the road, but of course you will struggle more on some terrain...

The open baffle are well rounded and perform really well, to my ears, with a wide variety of music.

In either case, I don't feel that the source/DAC/Amp is getting in the way of the music, on the contrary.

 

[hopkins]

Found this amusing, so I thought I would share it.

 

[hopkins]

Just ordered a pair of 400€ three way floor standing speakers:

Ultima 40 | Teufel

Ultima 40 ab 449,99 € (16/04/2024): Paire d’enceintes colonnes Hifi bestseller chez Teufel. Découvrir maintenant

teufelaudio.fr

Yes, such things exist and collect thousands of satisfied customer reviews. German brand. I will be modding them, however, with a completely redesigned crossover. Stay tuned

 

[hopkins]

Here's a good documentary on Billie Holiday:

Some context on the video is given here: https://www.jazzwax.com/2024/03/documentary-billie-via-linda-lipnack-kuehl.html

 

[hopkins]

Someone mentioned Akihiko Kaneda on another thread, and I looked him up. An article explains that he used to play digitized versions of LPs and they were hard to distinguish from a purely analog playback. I find that interesting, and reassuring at least for me who uses an ADC with my turntable.

I don't know whether we need to try to explain this, or debate it. I was listening last night to a Gene Ammons LP I just received : "Night Lights - Gene Ammons plays Nat Cole". I believe it is not available in digital format. The sound is really good. That's all that matters.

A few tracks from that LP were actually issued on a compilation CD. Here's one:

WIth vinyl, it seems that the potential for better audio quality is limitless as you upgrade turntables, arms, stylus... I don't think anyone would dispute the sound quality improvement I could get by upgrading from my basic Technics turntable (retail around 1500€) to most turntables in the next price bracket (say around 4000€). You get tangible sonic improvements from better "engineering".

With digital, the path towards improvement may be less clear for a lot of audiophiles?

 

[hopkins]

Concerning these 400€ speakers (Teufel) here's a good "no nonsense", and refreshingly honest review:

It is interesting to listen to entry level equipment!

 

[hopkins]

The review I mentioned above is spot on.

Really enjoyable "balanced" and cohesive sound as-is, and works great for TV/YouTube/Movies. The room interaction is perfect, and they are easy to place. So first impressions are shockingly good for a 400€ speaker.



More to follow...

 

[hopkins]

I put my girlfriend to work on my speaker project today. I had her compare the sound of my Teufel speaker, the stock version against a modified version (listening to a single speaker). Our opinions were similar, but it took her more time and effort to articulate them. She noticed how difficult it was to remember the sound of one speaker after switching to the other. Non audiophiles have an uncanny ability to focus simply on the music and it is hard to get them to "hear the sound"!

 

[hopkins]

A 200€ speaker (half of the 400€ 2-speaker set)!
This is the "stock" speaker (not modified). It sounds good, and I can see why it could make many budget-conscious music enthusiasts happy.

 

[hopkins]

So I implemented a new crossover on one of the Teufel Ultima 40 speakers. It was suggested by ECDesigns. I think they initially bought a set of these speakers to test out their amp (powerDAC-SX) on lower sensitivity speakers, and then got the idea to improve the crossover. The crossover is as simple as it gets. It consists in:

- a 4u7 capacitor in series with the tweeter
- a 0.27mH coil + 47uF capacitor in series on the midrange
- a 2.7mH coil in series with the 2 woofers


The sound quality is really very good with the new crossover, but I will comment on it in more detail after having modified the second speaker, and after spending more time listening. I spend three hours last night listening to a single speaker (only one modified so far) and I have to say it was a very pleasant experience, on all types of music.

Volume level is not an issue with the powerDAC-SX, ar least in my living room sitting at roughly 2.5 meters from the speaker.

They also sound great when used with my TV, and as noted in that YouTube review, are a huge upgrade on my soundbar. For that sole purpose, they are a no-brainer.

The build quality of the speaker, given its ridiculously low cost, is actually quite good. The components are obviously cheap, but the whole thing is solidly build. These are produced on a large scale. I would be curious to know how many of these they have sold. On their website it states that the speakers were sold over 1.100 times in the past 30 days... Are all German households equipped with these?

I did replace the speaker binding posts, which don't offer a tight grip on banana plugs. The speakers come without spikes, which may not be a problem for some, but on my uneven floor they are not perfectly stable. They do come with adhesive rubber pads that you can stick underneath the base. The bottom plate has holes to screw in footers. I will see what I use.

 

[hopkins]

For what it's worth, here's a video of a single speaker with the new crossover:

I think most would agree this is a pretty good "bang for the buck"! It sounds great listening in my room. Diminishing returns of high end audio have never been so obvious?

I'll record more challenging music once I have the second speaker modified (need to order some new internal wires).

 

[hopkins]

It's not so easy comparing the sound of two single speakers if you don't have a "balance" setting on your amp and if you don't use a true mono source (with no level imbalance).

By the time you have unplugged one speaker and plugged the other back in, you've forgotten the sound you just listened to.

I've been using the WiiM Pro's app, setting the audio output to mono (which mixes the tracks down from stereo...) and using its balance setting. It makes it pretty easy to compare the sound from the left and right channel "instantly":



These settings apply to any source going through the WiiM Pro: LMS, Qobuz, Spotify, or my turntable (with the M2TECH ADC).

I am using this to check the sound of one modified Teufel speaker against the other non-modified speaker. I assume this could be of interest for anyone wanting to check how their left and right speaker placement sound, or to compare speaker cables, even perhaps mono amps.

Of course our left and right ears may not perform exactly alike. I know, having been to an audiologist, that my right ear has a little more less sensitivity than my left one!

 

[hopkins]

Here is a picture of the stock crossover of the Teufel Ultima 40 speakers:



There are 10 parts. I don't know about the part quality, but they are all crammed on a small plate, and I understand that it is not a good idea to place coils so close together along with other components.

The new crossover contains only four components. The two coils are placed at opposite ends of a 20 cm plate.

All this makes a clear difference when listening. Bass is tighter, and instruments are better defined, sounding "purer" and fuller. This is obvious when doing quick A/B comparisons as outlined in my previous post.

Concerning bass, ECD mentioned something about why first order crossovers and the SX worked well together, but I don't have the detail reasoning behind this.

These budget speakers are obviously not without limitations. My open baffle speakers, and Altec speakers, offer more resolution. But these budget speakers still offer a very pleasant sound.

It is also obvious to me that there are common points between the sound produced by these three very different speakers when used with the powerDAC-SX.

 

[DasguteOhr]

Here is a picture of the stock crossover of the Teufel Ultima 40 speakers:

View attachment 127611

There are 10 parts. I don't know about the part quality, but they are all crammed on a small plate, and I understand that it is not a good idea to place coils so close together along with other components.

The new crossover contains only four components. The two coils are placed at opposite ends of a 20 cm plate.

All this makes a clear difference when listening. Bass is tighter, and instruments are better defined, sounding "purer" and fuller. This is obvious when doing quick A/B comparisons as outlined in my previous post.

Concerning bass, ECD mentioned something about why first order crossovers and the SX worked well together, but I don't have the detail reasoning behind this.

These budget speakers are obviously not without limitations. My open baffle speakers, and Altec speakers, offer more resolution. But these budget speakers still offer a very pleasant sound.

It is also obvious to me that there are common points between the sound produced by these three very different speakers when used with the powerDAC-SX.

The proximity of the coils is not a problem as long as they are arranged at 90 degrees to each other (magnetic field). If you change the filter slope, you have to be aware that you also have to change the crossover frequency, otherwise tweeters could be damaged at higher volumes or midrange speakers could suddenly produce significantly more distortion because they have to work outside their range due to the flat filter slope. Have fun building.

 

[hopkins]

The proximity of the coils is not a problem as long as they are arranged at 90 degrees to each other (magnetic field). If you change the filter slope, you have to be aware that you also have to change the crossover frequency, otherwise tweeters could be damaged at higher volumes or midrange speakers could suddenly produce significantly more distortion because they have to work outside their range due to the flat filter slope. Have fun building.

I have implemented the crossover without asking myself these questions, as I did not design it, but will either get or calculate the crossover frequencies or measure the individual drivers. The results are good, that's all I can say for the moment.

I actually don't know the impedance of the tweeter, but a 4.7 micro farad capacitor results in a high frequency cutover point.

 

[DasguteOhr]

everything is fine if you are satisfied, I just wanted to point it out.
if the cement resistor is in front of the tweeter, please replace it, use a better example e.g mills 12 watt ressistor, it reduces distortion significantly.