I think I will just have to accept the limits and go ahead. The objective is to come up with a plan to build speakers for the small amp.
Constraints:
Cost of drivers
Shipping time of drivers
Simple construction
Easy to work with materials and tools
Will it work? Well, let's see.
Constraints:
Cost of drivers
Shipping time of drivers
Simple construction
Easy to work with materials and tools
Will it work? Well, let's see.
Those speaker drivers look remarkably like the ones I used in my traffic light speakers, 4 drivers in each (3 in the front, hence "traffic light", one in the rear). But even using four per side in closed boxes, they're still bass shy. Sorry, but there's no way you'll get bass from two in open baffles - I tried two 6 inch drivers and almost damaged them trying to get bass out of them, the best chance you've got is making big horns to get some bass. They are very good drivers for a very low price though.
Hi, rather late in the day, but could you possibly share some pictures and details of your PAM8403 setup with a recording? Point is, I am one of the few running low powered amplifiers, and would like to get some support.
I had a PAM 8403 once, sounded ok, a bit harsh, but as I found out these things are not very robust, and I shorted it out. Maybe time to buy one.
With connectors.
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Those drivers look just like the ones I used in these, my "traffic lights", 4 in each (there's a driver in the rear), these are what I'm currently driving with my pam amp, and they have more bass than they had with a more powerful amp, I'm guessing that down to the low damping factor of the pam. I've added about 10,000 if of electrolytic capacitance along with a 4 farrad super capacitor. I also added some inductors to the output, because I wasn't sure how much radio frequency stuff is present.
Amazon (UK) sell a cheap board using the pam 8406, which is even better than the 8403 (apparently). I'm tempted to give one a try.
Well well, more advantages. Are those 4 inch drivers? Does the line array produce more sound than a single range if they are wired in parallel - since the amplifier is mono, I am wiring my 4 Ohm speakers in series, which gives me less than 70 dB output unless I modify the mp3.
Also, does the speaker wire gauge make a big difference to output when using these small low powered amplifiers? I am getting some strange results with the speaker cables supplied with the car speakers.
Yes. I saw the PAM 8406 product, assumed it was a new improved version of the 8403.
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If I remember correctly, they are 3 1/2 inch, with woven glass fibre cones (I do seem to like the sound of woven glass fibre cones, I'm not sure if it's because they are good, or they have a particular distortion that I like) There are at least two threads on diyaudio about the improved sensitivity of wiring drivers in series and parallel by people who know lots more than myself. On my traffic lights, two drivers are wired in series, then those pairs are wired in parallel, so they have the same impedance as an individual driver. The driver has a capacitor across it, to take some treble from it and give more to it's partner (the front middle) At first I tried them without the capacitor, and they sounded terrible, because of the beaming effect.
Why do the PAM 8406 boards cost so much? $18 upwards and $ 100 upwards, is it a quality issue? The Ali Express ones are cheaper.
I ordered 3 yesterday, £7.99p each, free postage, they just arrived (I'm fortunate enough to be able to have my personal Amazon deliveries delivered to work), they look better made than the 8403 boards. I did notice that the price ranged from about £7.99p to well over £100, I don't know why this is. I only use Amazon for audio components because it means that I don't have to use a credit card on line, I've only ever used Amazon gift cards.
Great!
Off - topic but please let us know when you test them, maybe there is a thread.
Meanwhile this is the speaker for this amplifier. Some testing needs to be done... Thanks for the info on the "with woven glass fibre cones".
Here is the datasheet of the little amp: 3 Watts it says. The on board battery is rated at 3.7 V so there is room for improvement.
LTK8002D 是一款 3W 、单声道 AB 类音频功率放
芯片外貌
大芯片。工作电压2V-5V,以BTL桥连接的方式,在5V
电源电压下,可以给4Ω负载提供THD小于10%、平均
为3.0W 的输出功率。在关闭模式下,电流典型值小于
0.5uA。
Off - topic but please let us know when you test them, maybe there is a thread.
Meanwhile this is the speaker for this amplifier. Some testing needs to be done... Thanks for the info on the "with woven glass fibre cones".
Here is the datasheet of the little amp: 3 Watts it says. The on board battery is rated at 3.7 V so there is room for improvement.
LTK8002D 是一款 3W 、单声道 AB 类音频功率放
芯片外貌
大芯片。工作电压2V-5V,以BTL桥连接的方式,在5V
电源电压下,可以给4Ω负载提供THD小于10%、平均
为3.0W 的输出功率。在关闭模式下,电流典型值小于
0.5uA。
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Translation (Google Translate) :
Working voltage 2V-5V. Are you running your chip at max voltage? Any problems there?
Working voltage 2V-5V. Are you running your chip at max voltage? Any problems there?
A distortion of 10% is absolutely terrible (less than 0.01% is typical for audio amps), but the PAM amps and others I've used have between 10% and 3%, but sound really good, I can only presume that the 10% distortion is at peak power output, and at lower power the distortion is correspondingly much lower. I'm currently running my PAM amp on 3 AAA batteries, so about 4.5 volts, perhaps right on 5 volts when the batteries are first used. I'm butchering an old radio to use the mains transformer; I was originally going to use the 8403, but now the 8406 amps have come I'll use one of them.
This answers the question - from the datasheet. There is a site that lets you check how much distortion you can hear, let me check that out.
Anyway must not push this past 1 Watt, which means with an 80 dB / W sensitive speaker is 80 dB which I will never reach.
Anyway must not push this past 1 Watt, which means with an 80 dB / W sensitive speaker is 80 dB which I will never reach.
As stated in the title, the aim of this project was to develop a speaker for the TableProMG2 Bluetooth speaker, given the promising results from intial testing.
After listening to xrk971 's driver testing recordings, and also to the CU-3U speakers I built (U-shaped open baffle, car speaker) powered by the TEA 2025 amplifier, I realized that the bass response was totally different from the usual MG2 output.
Using the FM mode of the MG2, I recorded a 10 second clip with my A53 phone and ran it through the frequency analyzer in Audacity. The extremely pronounced higher frequencies show clearly. Adding EQ helps, but I am not sure the its worth it given the peaks and valleys. Next is to test it against the W4.
Images left to right: before EQ, after EQ, EQ settings.
After listening to xrk971 's driver testing recordings, and also to the CU-3U speakers I built (U-shaped open baffle, car speaker) powered by the TEA 2025 amplifier, I realized that the bass response was totally different from the usual MG2 output.
Using the FM mode of the MG2, I recorded a 10 second clip with my A53 phone and ran it through the frequency analyzer in Audacity. The extremely pronounced higher frequencies show clearly. Adding EQ helps, but I am not sure the its worth it given the peaks and valleys. Next is to test it against the W4.
Images left to right: before EQ, after EQ, EQ settings.
What sort of testing hardware do I need - in terms of microphone to take the recordings? I think the phone microphone may not be accurate enough, what about the phone headset microphones? I saw a professional recording engineer use a phone microphone with his mobile phone: can't remember the name of it, was not that expensive, about $30.
Anything good on Ali Express or Amazon or E bay?
Anything good on Ali Express or Amazon or E bay?
Attachments
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The inbuilt speaker of my phone the Samsung A53-5G gives a good enough recording of the speakers and music. The headphone microphone is terrible.
A Question about charging / power to the Tablepro MG2 Bluetooth Speaker
The battery of MG2 speaker is npw only good for about one or two hours of play. I cut out the internal battery and added a 3 AAA battery holder, connecting it directly to the wires that previously connected to the battery. The output is 4.79V from the three brand new batteries. The green and yellow jumper cables on the right side of the image are connected to the 3 AAA batteries.
When running the MG2 off the USB charging cable, which inputs 5 V, does this mean that the unit is running off 5V or is the voltage regulated to the 3.7V normally produced by the battery, so as not to make a large difference in volume when the charging cable is connected - it does this when the battery low indication sounds, but not at other times.
What is the typical arrangement for a charging circuit using a 5V usb cable to charge a 3.7V Lithium Ion battery?
The sound off the 4.79 is much better and crisper than before, and I am very pleased with it. Let's see how long this lasts. The 8002D is rated for 5V input.
https://batteryuniversity.com/article/bu-411-charging-from-a-usb-port
The green and yellow jumper cables on the right side of the image are connected to the 3 AAA batteries.
The battery of MG2 speaker is npw only good for about one or two hours of play. I cut out the internal battery and added a 3 AAA battery holder, connecting it directly to the wires that previously connected to the battery. The output is 4.79V from the three brand new batteries. The green and yellow jumper cables on the right side of the image are connected to the 3 AAA batteries.
When running the MG2 off the USB charging cable, which inputs 5 V, does this mean that the unit is running off 5V or is the voltage regulated to the 3.7V normally produced by the battery, so as not to make a large difference in volume when the charging cable is connected - it does this when the battery low indication sounds, but not at other times.
What is the typical arrangement for a charging circuit using a 5V usb cable to charge a 3.7V Lithium Ion battery?
The sound off the 4.79 is much better and crisper than before, and I am very pleased with it. Let's see how long this lasts. The 8002D is rated for 5V input.
https://batteryuniversity.com/article/bu-411-charging-from-a-usb-port
The green and yellow jumper cables on the right side of the image are connected to the 3 AAA batteries.
The batteries lasted 1 hr 30 minutes before the low battery warning alarm came on, at 4.4 V or so. Sound was exceptionally clear, which I note for future use.
A certain Hi -Fi expert I know runs his stuff off batteries. Connecting the USB charger cable resulted in a more harsh, distorted sound. The USB standard is 500 mA or so, possibly. Might as well run the thing off the charger, permanently.
Maybe run it off a power bank.
The AAA batteries have since recovered since last session.
A certain Hi -Fi expert I know runs his stuff off batteries. Connecting the USB charger cable resulted in a more harsh, distorted sound. The USB standard is 500 mA or so, possibly. Might as well run the thing off the charger, permanently.
Maybe run it off a power bank.
The AAA batteries have since recovered since last session.
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You get battery charging controllers for Lithium batteries, common item on line, very cheap.
Crude solution is 1N4007 + 2.2 ohm resistor, drop the voltage from 5V (charger) to below 4.3 (safe limit), and use that to charge battery. Usually 2-3 hours is enough.
Old cell phone battery will be available, or use 3000 mAH cell in 18650 size.
Crude solution is 1N4007 + 2.2 ohm resistor, drop the voltage from 5V (charger) to below 4.3 (safe limit), and use that to charge battery. Usually 2-3 hours is enough.
Old cell phone battery will be available, or use 3000 mAH cell in 18650 size.
For more efficiency and better bass
could try budget 8" full range or wide band speakers.
like BG20
When I did fool around with car audio speakers.
I found the Oval speakers worked better
5x7 perform close to 8" speaker
and larger 6x9 close to 10" speaker.
many have integrated 2 way or 3 way drivers
Numerous luxury or high end vehicles
also have impressive 2 way or 3 way systems.
some have separate tweeters and mids
I would acquire very nice speakers cheaply at automotive
junkyards. Or from towing service yards.
Often very new cars are involved in wrecks.
And have rather nice sound systems.
Way before bluetooth and streaming.
Just a tape deck and CD was more than fine.
Used luxury car factory decks on 12 volt supply.
Tape deck , CD , Radio, Equalizer and radio presets
Sure the concept could be applied to modern times
since many cars come factory with bluetooth and numerous
multi speaker outputs and equalizer options.
Acquire for very affordable price from wrecked vehicles.
could try budget 8" full range or wide band speakers.
like BG20
When I did fool around with car audio speakers.
I found the Oval speakers worked better
5x7 perform close to 8" speaker
and larger 6x9 close to 10" speaker.
many have integrated 2 way or 3 way drivers
Numerous luxury or high end vehicles
also have impressive 2 way or 3 way systems.
some have separate tweeters and mids
I would acquire very nice speakers cheaply at automotive
junkyards. Or from towing service yards.
Often very new cars are involved in wrecks.
And have rather nice sound systems.
Way before bluetooth and streaming.
Just a tape deck and CD was more than fine.
Used luxury car factory decks on 12 volt supply.
Tape deck , CD , Radio, Equalizer and radio presets
Sure the concept could be applied to modern times
since many cars come factory with bluetooth and numerous
multi speaker outputs and equalizer options.
Acquire for very affordable price from wrecked vehicles.