Peachtree Audio deepblue2 Table-Top Bluetooth Speaker Page 2
I had the deepblue2 up and streaming from my Galaxy Note 4 about as fast as I could unpack it, and it sounded just fine right out of the box. The next day I hooked it up optically to my little old MacBook and it sounded bad...way too much treble. Wait...it sounded great last night. What the heck is going on?
It took me a little while to figure out what was going on. It seemed like the tonality was changing as the volume on the deepblue2 changed. When I had used the phone, I had the volume on the deepblue2 set fairly high, and adjusted the the listening level from the phone. When I used the digital output from the computer, the computer volume by default was set to max for best digital resolution, and I adjusted the listening level with the deepblue2 remote. The problem is, the deepblue sounds very different in these two situations. It sounded flat when the deepblue2 was set to about 3/4 volume, but sounded bright and bass heavy from the computer when the deepblue2 setting was at 1/4 volume but the listening level in the room was the same.
It seemed to me that what might be happening is that the deepblue2 had some sort of Fletcher-Munson loudness curve attached to the volume control, and when I fed it a very loud signal digitally from the computer and had to turn the volume down significantly for my desired listening level, at which point it had too much bass and treble because it was on the low volume loudness contours. To verify that something was going on and my ears weren't hallucinating, I emailed some questions to Andrew Clark, CEO of Peachtree Audio. Below is our exchange:
Tyll Hertsens - I think I'm hearing a difference in treble response as well. It sounds like you're adding in some Fletcher-Munson curve as volume goes up and down. Is this truethat both bass and treble are effected?
Andrew Clark - Yes. You are correct. As volume is reduced, the midrange is reduced in level the most. We don't use the Fletcher-Munson curves (actually quite a bit different) but the concept is the same.
TH - If so, is it the look-up table for curves directly connected to the Deepblue2 volume level setting? Or does the Deepblue2 actually sense the output volume to select the setting?
AC - The EQ is tied directly to the DB2 volume setting. There are 20 volume steps, therefor 20 baseline curves. Then there are 10 bass steps per volume setting providing a total of 200 EQ curves depending on the volume and bass control setting.
TH - Here's my real point: If I have the DB2 at about half volume and my phone volume all the way up, the DB2 sounds a tad bright in the high treble for me. If I max the DB2 volume and set the listening volume from my phone, it sounds just a bit dull and too mid-forward. When I set the DB2 at 3/4 volume and adjust my phone for listening level is sounds about right. Am I hallucinating here, or is both the bass and treble changing with DB2 volume directly?
AC - Correct. The optimal way to ensure you are getting the benefit of the loudness EQ is to use a BT device with AVCRP so the volume is controlled at the DB2 or to put the connected device output level up and use the DB2 volume control to control gain down. To accomplish something more sophisticated, we would have to design some sort of internal signal loudness analysis DSP or to monitor the signal and adjust the EQ to the input signal level. That has its own drawbacks as some music can be quite dynamic. Probably ok to do something like this on modern popular recordings as they are compressed to within an inch of their life, but classical and jazz ranges would cause EQ changes as music got louder or softer. Or go the way the home theater folks do and have some sort of microphone/room/volume calibration. However, that would be difficult with the different mixing and mastering levels used for different genres and older recording were done differently. At least Dolby helped to standardize the film industry on levels. Too bad there wasn't a similar thing that happened for music.
A good challenge for sure!
Aha! I'm not going nuts, the deepblue2 sounds different depending on where the volume control is set. And with that knowledge in hand, I knew how to set the volume of the deepblue2. I set the volume control of the deepblue2 to about 3/4 level; then I set the volume on my phone or other playback device so that I'm hearing a solid listening levelsay 75dBspl C-weighted. From then on I use the volume control on the deepblue2 to adjust how loud in the room I want the music. If I use the deepblue2 volume control to lower the level, then the bass and treble automatically turn up as needed for roughly equal loudness of all frequencies. Once you get the hang of it, the tonality remains nicely consistant and satisfying at all listening levels. The additional bass level control allows you a nice tweak from song to song if you want to play around with it.
The thing is, this concept is not spelled out in the manual. I'm a card-carrying audio geek, and even I had to get some help to make sure I knew what was going onyour average customer is going to be completely clueless. Is it really a problem? I suppose not, again, most people are just going to be clueless, and generally speaker levels are such that you're not going to be too far off the proper loudness contour curves anyway. One alternative would be just to have a system that plays flat all the time, but then you have the opposite problem that when playing at a low volumewhich I personally do a lotit gets boring sounding, lacking in both bass and treble. Another alternative, one that appeals to my inner geek, is to have a companion app with a bunch of bells and whistles. The problem is, while I say it's appealing, in really I rarely use stuff like thatwhat I really want is for something to sound good with very little fuss.
The deepblue2 absolutely delivers no muss-no fuss performance. Once I got the hang of where to set the volume control it sounded just great at every listening level. The bass response is its outstanding characteristic extending lower and delivering tight bass like no other wireless speaker I've heard before. With a 200 Watt class-D amp driving the 6.5" bass driver in a sealed cabinet, you don't get any of that smeared out bass response often heard with passive radiators or ported designs. The deepblue2 flat out rocks the bass.
Another notable sonic characteristic was its ability to play loud...really loud. As I played around with loud levels, I began to see the deepblue2 as more akin to a small PA speaker than a large table-top wireless speaker. With 440 Watts of class-D power amplification driving the 5 speakers within, the deepblue2 will have no problem pumping out the jams for a suburban back yard party.
Other than the two remarkable sonic characteristics mentioned above, the sound of the deepblue2 was otherwise quite unremarkable...in the sense that it seemed just right so much of the time. I could pick nits and say the tweeters sometimes sounded a tad gritty, and sometimes the tonality seemed a little off. But I don't expect a Bluetooth speakers to have the resolving power or liquidity of full-size hi-fi speakers, I just hope for competent playback without distraction from harsh or honky colorations. And that's the point, the deepblue2 doesn't draw any attention to itself with artifice or artifact. It's just a plain black box pumping out competent audio at any level on demandand it does that as well, or better, than any other Bluetooth speaker I've experienced.
The Peachtree Audio deepblue2 easily plays in the sound quality league of best Bluetooth speakers I've heard to date at any price, and on the strength of its amazingly taught and extended deep bass response, probably bests them. This is a great sounding Bluetooth speaker.
The deepblue2 has built in loudness compensation curves that link directly to its volume control. Because of this, it is important to set the volume of the deepblue2 to about 80% volume (4 of 5 lights), and then set a solid listening level with the input device. Thereafter, all volume adjustments should be made with the deepblue2.
Once you get used to setting the volume control correctly, the deepblue2 unwaveringly cranks out well balanced, room filling sound. At $499 it's not cheap, but this is a terrific speaker for the demanding audio enthusiast who just needs to put good sound anywhere in the home on demand without feeling like they've had to compromise their sensibilities in the process. Highly recommended.