My experiments with speakers and amplifiers located in the subterranean layer of the Hi - Fi world continues. Subterranean in terms of cost.
Here is my latest project, which is proceeding nicely: When the TEA 2025 amplifier stopped working properly, I hit upon the idea of connecting an inexpensive speakers to my existing Whafedale Diamond IV speakers. The results were surprising, while bass was totally lacking, it could be boosted using the music player (Musicolet) equalizer for acceptable levels of musical enjoyment.
I am in the process of building a set of speakers specifically for this little Bluetooth amplifier, with some success. I am getting 70 dB at 1 metre with these connected to large vintage floor standers of 89 dB sensitivity.
I had a few questions though.
Here is my latest project, which is proceeding nicely: When the TEA 2025 amplifier stopped working properly, I hit upon the idea of connecting an inexpensive speakers to my existing Whafedale Diamond IV speakers. The results were surprising, while bass was totally lacking, it could be boosted using the music player (Musicolet) equalizer for acceptable levels of musical enjoyment.
I am in the process of building a set of speakers specifically for this little Bluetooth amplifier, with some success. I am getting 70 dB at 1 metre with these connected to large vintage floor standers of 89 dB sensitivity.
I had a few questions though.
Images of the speaker, the internal board which seems to have an 8002D amplifier IC doing all the amplification work.
I would have abandoned low power amplifiers long ago if not for the results with various types of speakers and amplifiers. Right now I can prefer my existing set up to the Sony XBS Bluetooth speaker I have. According to reviews, at high volumes bass distortion occurs.
It's logic. Lower bass notes needs large speakers with large power capability in the amps and speaker itself, so don't expect good bass plaback from a 40mm speaker and 500mW power amp.
This is the image - representation of the system. In front is the Bluetooth speaker unit, with the internal speaker wires extracted out of the case and connected to a clip-type connector. In the background are the SONY speakers. The other image is one of the Musicolet app equalizer settings that gives me better bass and clarity.
https://www.flipkart.com/esportic-m...ble-wireless-5-w-bluetooth/p/itm54f94db641cfb
This is a nice setup for listening, however I cannot take these speakers with me, so I will have to build an open baffle pair with a 6 inch woofer and some sort of tweeter. The speakers are connected in series.
Questions: Has anyone else tried this? What were the results? Does anyone notice a blurring of music and an empty mid-range in commercial systems especially car audio?
https://www.flipkart.com/esportic-m...ble-wireless-5-w-bluetooth/p/itm54f94db641cfb
This is a nice setup for listening, however I cannot take these speakers with me, so I will have to build an open baffle pair with a 6 inch woofer and some sort of tweeter. The speakers are connected in series.
Questions: Has anyone else tried this? What were the results? Does anyone notice a blurring of music and an empty mid-range in commercial systems especially car audio?
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Yes, so the 40 mm speaker was disconnected and connected to larger speakers. The circuit seems to have been designed to cut out the bass frequencies, so it is difficult to get bass out of the output without a large box speaker and boosting the bass frequencies.
A review of the unit is here:
The recommendation is don't buy, but for $ 7 if you do buy it and connect it to two $15 bookshelf speakers then you will have quite a good system to listen to. Two speakers, even in mono, in series can generate a sound stage of sorts. The reviewer says he could not get the FM radio to work, same experience I had. No attempt was made to equalize the phone Bluetooth signal output which is a pity.
There are also videos of connecting cheap Bluetooth speakers to large speakers, but none of the videos I have seen make use of an equalizer which is vital with any Bluetooth speaker, even commercial ones, to obtain clear sound.
Testing with two car speakers gave much better results in the bass, however the level of EQ required (this was in open baffle format) was very high. I am considering building a box for the speaker drivers just for the TablePro MG2 . The tweeter of the car speaker generated a lot of distortion, noise, so the wires to the tweeter were cut and the tweeter unit was removed. Sound was much better.
In fact I haven't any one. I still prefeer wired ones. Else, how to start systematic cable worries questions?
Interestingly, a comparison with the original amplifier for the speakers was done, and the little Bluetooth device was clearer and more detailed, however, the sheer power in the bass frequencies were absent, but with proper equalization I preferred the small amplifier to the 20+ year old vintage receiver. Age matters, especially for capacitors, I think.
Here is a pic of the system, however powered by a bigger amp, I measured the power consumed by the amp driving these ineffeciant speakers loud, and it was only less than 1 watt for both channels, I'd like to know what this translates to as peaks. I think this is why low power amps sound surprisingly good, because most of the time we're listening to a fraction of a watt. I'm going to experiment with a low power amp, but with a decent power supply (4 farrad super caps)
Unfortunately my main amp has developed a fault (a clicking noise once a second) so my hand was forced in experimenting with a PAM8403 amp (3 watts each channel and dirt cheap) combined with a 4 farad cap on the power supply (currently 3 AAA batteries); at first is sounded a bit dull, but as the night went on it improved to the point that I was actually giggling at how well it played Rage against the machine. Low power ROCKS!
That is what I am finding. Recently I was playing the BlueTooth speaker connected to the large floor-standers (up on a shelf but nevermind) and my visitor remarked "that amp is quite powerful". I told him it was less than 1 Watt. He is used to listening to his Rotel amp, presumably at 90dB and playing along with his drums.
In all comparisons I have found that apart from a lack of bass ( a delibrate filtering effect I think) the little 8002D comes out well in clarity and somewhat in punch. Many of the standard Hi-Fi amps sound like they have a large capacity damping the sound, the 'attack', that is my opinion, though, I have no way of proving it. The only thing I can think that would reveal it is the 'slew rate' measurements, and that we know is not relevant anymore.
With speakers. 'you can hear things you don't measure' (will find the quote) could it be so with amplifiers?
Have you seen any of Nelson Pass's videos? He believes in the first watt, I think.
To put it in perspective on just how little power it takes to fill a room with sound, when I disconnect the batteries, the amp will play for about 5 - 10 minutes on the 4 farad capacitor, a tiny motor would only run for about 15 seconds.
I would presume that a low power amp would need less gain, hence need less amplification stages, reducing distortion - perhaps smaller transistors have less "memory effect" ?
I agree that the bass could be curtailed by a low value input capacitor; lets face it, the amp would be intended to be used with speakers that don't go near 100 Hz, but it could also be helped by a stiff power supply, although I'm starting to think 4 farad is overkill...
I would presume that a low power amp would need less gain, hence need less amplification stages, reducing distortion - perhaps smaller transistors have less "memory effect" ?
I agree that the bass could be curtailed by a low value input capacitor; lets face it, the amp would be intended to be used with speakers that don't go near 100 Hz, but it could also be helped by a stiff power supply, although I'm starting to think 4 farad is overkill...
So, designing and building speakers - let's start with the drivers - for simplicity, in open baffle format.
Preferably low cost drivers - under $10 with shipping. The result of this is a plan and recommendation for a set of speakers in an emergency for the Bluetooth unit shown, the TablePro MG2.
The Pioneer car speakers are one option, however I am open to online purchase of a set of speakers 2 inch 4 inch whatever.
Preferably low cost drivers - under $10 with shipping. The result of this is a plan and recommendation for a set of speakers in an emergency for the Bluetooth unit shown, the TablePro MG2.
The Pioneer car speakers are one option, however I am open to online purchase of a set of speakers 2 inch 4 inch whatever.
Open baffles are not conducive to getting results in a small package. Sure, there were many portable sound systems in the past with open baffles (for simplicity), and they sounded good within their limits. Since you're pushing the limits you should know how difficult this can be.