Open Panzer
Open Panzer Help & Info => Open Panzer Help => Topic started by: Lotuswins on April 09, 2018, 10:36:46 PM
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Hi Luke,
So I have my T55A working great with the TCB, and the Taigen sound card, but its spitting out the PIV sounds (....that is all I know of that they have right now).
I just rec'd the Benedini Mini with the T55A sounds set up for the TCB, and I read that a 3 position switch is needed to control the volume. Since the 3 position switch on my 9X turnigy is already reserved for engine start/stop....as it is on all of my tanks....is it possible to control the mini sound volume using one of the pots?? Can you recommend how to set that up?
thanks for any help, Jerry
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Sadly that is not an option with Benedini's products. I asked him to consider it once but I think it would have come at the expense of other functions more important. In any event, the present system using a switch is the only way to achieve volume control, this is true regardless of whether you use the Mini with the TCB or on its own.
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Can I 'simulate' a switch with the pot?? low (zero) ohms, position 1, and high (100k) as position 3, mid level, mid position?
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Yes of course, you can use a "pot" channel as a "switch" channel and the functionality will be the same. When you move the pot all the way to one extreme it will be as if you had put the switch to one position, and at the other extreme the other position. You will not be able to adjust the volume exactly according to the position of the "pot" as you had in mind originally, but if the only physical control you have left is a pot then you can assign it to these functions and it actuate it as if it were a switch.
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Hi, I did something similar with the benedini micro. With a pot in the minimum position the volume lowers slowly until is completely muted, and at maximum position keeps rising until maximum volume.
You dont need a 3 pos switch, you can do it with any switch in you radio, but if you dont have a heavily modded 9x using a pot is a great idea.
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Thanks for the info guys, as I was wanting to adjust volume with the pots also.
I will give it a try.
Shad
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Hi Luke,
So I use channel 7 on the 9x for volume, Pot #2, and I setup the TCB with Channel 7 as Aux 3, digital 3 position switch. Function setup is: Position one is start raising volume, position two is stop volume, and three is start decreasing volume. It works a treat.
A side question on the Benedini though, I purchased some very small rectangular speakers in 8 ohm impedance, and hooked it up today. The volume is very low compared to others on 4 ohm speakers like the Taigen sound card. Same size speaker, just different impedance. Will I smoke the Benedini with a lower impedance speaker?? It does look rather delicate....
thanks, Jerry
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So I use channel 7 on the 9x for volume, Pot #2, and I setup the TCB with Channel 7 as Aux 3, digital 3 position switch. Function setup is: Position one is start raising volume, position two is stop volume, and three is start decreasing volume. It works a treat.
Thanks for reporting back. In this case we are still using a 3 position switch so far as the TCB knows, but in reality you have a pot as the actual control. It is good to remember the user is free to assign a variable ("analog") physical control as a digital switch in OP Config, and vice-versa, the suggestions are not hard and fast rules. However there is not often a need to do so, but this is an example of a time where it makes sense.
A side question on the Benedini though, I purchased some very small rectangular speakers in 8 ohm impedance, and hooked it up today. The volume is very low compared to others on 4 ohm speakers like the Taigen sound card. Same size speaker, just different impedance. Will I smoke the Benedini with a lower impedance speaker?? It does look rather delicate....
Actually, according to this user who contacted Thomas about speaker impedance (http://openpanzer.org/forum/index.php?topic=118.15), the Mini should only be used with 8 ohm speakers (directly, if you use an external amplifier with the Mini then that may not be a limitation). All else being equal, a 4 ohm speaker will draw twice the current of an 8 ohm speaker, so yes, it would seem 4 ohm speakers may risk damage to your Mini.
I've been using an old Heng Long speaker on my Mini for years, I don't remember where exactly I got it. But it measures 8 ohms so apparently they do exist from the standard manufacturers. It was probably from an old RX18. However like you I measure a more recent Taigen speaker to be 4 ohms.
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Hi again,
So I looked at the details of the Mini, and it has a whopping 1.2 watts output? Wow, how are you satisfied with that volume...w/o an amplifier?? I don't know what the HL or Taigen outputs are, but surely it must be at least double this??
So it looks like an amp is in my future.....
Jerry
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I guess each user is different. Personally I don't care for sound to begin with and the only time I've used the Mini or even my own sound card is for testing, and then at reduced volume.
However I will say that with the correct speaker (such as my 8 ohm Heng Long or a Visaton) the Mini can get surprisingly loud. I think it is every bit as loud as stock Taigen/Heng Long/Tamiya.
But yes, 1.2 watts is not very much. I thought I would get ahead of the curve and my original sound card prototype implemented a 2.6 watt amplifer (and was compatible with 4 ohm speakers). People complained and said it needed way more. Already my ears were bleeding. The new design I'm working on now has 10 watts but it amplifies sound so much any dead space in a sound file comes across as a very loud hiss, and it picks up any stray signal or interference and has become nearly impossible to get a clean output from... I don't blame Thomas for sticking with the low watt design!
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Hi Luke,
So I went trolling for a amall, mono amplifier, and not liking the Benedini options, found this 2.5W model:
https://www.adafruit.com/product/2130?gclid=EAIaIQobChMI6efijeu82gIVDlmGCh0FTwlUEAQYASABEgKdn_D_BwE
The question is how to connect it to the Benedini Mini....I see in the Mini manual that he recommends a 220 ohm resistor in series with a 220 pot from Negative speaker out to ground, and the output is the wiper of the pot and ground. This kinda seems wierd to me, and I would have to hang the pot and resistor somewhere. I really would like a much cleaner approach.
I was planning on powering it with the 5.5v BEC off the TBS, so that would go to 2-5VDC and GND on the amp. The two outputs from the Mini go to the A Plus and A Minus on the board input, and of course I would install a JST male on the board for the speaker to plug into (4 ohms works on this too). Since A+ and A- are fully differential, it should work? What do you think?
Thanks, Jerry
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I was planning on powering it with the 5.5v BEC off the TBS, so that would go to 2-5VDC and GND on the amp. The two outputs from the Mini go to the A Plus and A Minus on the board input, and of course I would install a JST male on the board for the speaker to plug into (4 ohms works on this too). Since A+ and A- are fully differential, it should work? What do you think?
I'm not an audio design expert and I don't know why Thomas recommends the hookup arrangement he does. What you suggest seems logical enough and you could try it, but to be safe you should ask Thomas first.
Let us know the results. That's a very inexpensive amp and if it made a noticeable difference without much hookup hassle people would be interested to know.
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Thanks for the quick reply Luke.
I just emailed Thomas, so we'll see what he recommends.
Also, as a side note on speakers, I have an old Heng Long KV1 that has remained pretty much stock and was a 2.7khz radio tank initially. I measured the speaker DC resistance yesterday, and it is 6.5 ohms. That is wierd.....oh, well. It's too bulky for the T55A anyways (I would have to cut the speaker enclosure up to make it fit) but I thought it was interesting that its an in-between speaker.....
Jerry
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I measured the speaker DC resistance yesterday, and it is 6.5 ohms. That is wierd.....oh, well.
Hi,
the ohms what you measure is not the speaker impedance...
the speaker impedance is a measure of the resistance of a loudspeaker to alternating current.
this is usually the case at a frequency between 250 and 400 Hz.
what you have measured is the DC winding resistance of the speaker coil
but it is an indicator which impedance the speaker can probably have.
In your case, it seems like an 8 ohm speaker.
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I don´t have a benedini mini, but with a micro, the impedance is critic! I had a lot of 4ohm speakers of all sizes, ranging from very small and flat laptop speakers to a home cinema ones that I scavenged, and no one of them works well with the micro. No matter what I tried it was a no go for me.
Then I plugged an 8ohm 1w speaker, and sounded very good. Then I tried another 8ohm 1w speaker but bigger and the sound was even better.
So whatever you do, buy a 8ohm speaker. The bigger the speaker and the box, the better. In case you need more power, you can add an amp like this one: https://www.ebay.com/itm/XPT8871-DC-3V-3-7V-5V-Mono-5W-Mini-Amplifier-Board-Audio-Amp-Module-One-channel/322979591569?epid=560313104&hash=item4b33157591:g:1gsAAOSwgZ1XtGeb
Hope it helps... I am not expert and this is not based in any scientific knowlegde, those are just my experiments...
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Hi all,
Okay, I got the Adafruit amp in the mail last night. BTW this is what Thomas Benedini wrote back to me regarding hookup:
My Quiry:
Hi Thomas,
I would like to connect the Mini I just received from you to this Adafruit Amplifier:
https://www.adafruit.com/product/2130?gclid=EAIaIQobChMI6efijeu82gIVDlmGCh0FTwlUEAQYASABEgKdn_D_BwE
Is it possible to connect it without the 220 ohm resistor and potentiometer? Just simply connecting the BEC 5v from the OP TCB to power it and the audio input (Speaker + & -) from the Mini directly to the A+ & A- on the amp?
I'm really cramped for space in my T55A RC tank, and I'm hoping just cables are needed to use this 2.5W amplifier.
Thank you for any help, Jerry
His response:
Hello Gerald,
this seems to be possible, by having a look only to the picture.
Having the schematic would be better.
No guarantee on any damages !!!!
I hope this helps.
Best regards
Thomas
So I hooked it up this morning, using a 4 ohm, 1 x 2 inch speaker (Mato sells them, as does Amazon). I think, not sure, they are rated at 3 watts. And all worked, volume is more in line with the other tanks, Taigen, HL, etc. Happy except the cannon sound for the T55A is a little disappointingly soft IMHO. I plugged a pair (total 4 ohm) speakers, rated 3 watts each, and it worked even better.
So great outcome, for $3.95 plus shipping.
Thanks, Jerry
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Great find Jerry!
I have a couple of these AMPS I bought from Dan at Battle Armor with the TBS minis when he was still in business.
They are larger than the one you have. I like yours for use in smaller spaces. I think I might try one to see how it compares.
This was off Battle Armors site;
This little gem produces 15 W X 2 channels of clean sound to give your tank some rumble and punch.
Customized to make hook up to the Benedini TBS quick and simple
Thanks
Shad
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The AMP that Chad got from Battle Armor is no longer available from Thomas Benedini its been discontinued .
But here is a couple I found on Amazon .
https://www.amazon.com/DROK-Portable-Amplifier-Automotive-Motorcycle/dp/B00C4LB57A?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00
https://www.amazon.com/DROK-Amplifier-Dual-channel-Amplifiers-Potentiometer/dp/B00C4N410G/ref=pd_bxgy_328_img_3?_encoding=UTF8&pd_rd_i=B00C4N410G&pd_rd_r=7591ZQWWZR7F2VKEHPVK&pd_rd_w=dxEYg&pd_rd_wg=l2R9Y&psc=1&refRID=7591ZQWWZR7F2VKEHPVK
Thanks
Jimmy
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So back on the original topic of the volume control of the Mini with a pot, I finally got tired of always looking down to see if the volume pot was centered on my tanks with the Mini in them, so I just replaced the 9x pot with a three position switch, spring center off, single pole identical to ON1/ON2 switch. 15k resisters between the center and outer poles, and wired just like the pot (center wire to center pole, and outer wires to outer poles), and put it in place of the P3 pot since I use P2 for all the taigen sound card and IBU2 tanks with servo driven pots and P3 isn't used for anything on any of my tanks.
And it all works great with only having to reassign channel 7 to P3 rather than P2. I am very pleased that fiddling with the volume pot isn't required on the tanks with the Mini in them (currently 3....).
HTH, Jerry
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That's a good idea Jerry, thanks for sharing. I've always wished the 9x had more 3-position switches and I always replace one of the pots with a switch just as you have done, even if you're not using the Benedini it can still useful.