Author Topic: 38W x 2 stereo amplifiers  (Read 5386 times)

Offline Toxxyc

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38W x 2 stereo amplifiers
« on: March 23, 2017, 07:42:46 AM »
Hi guys, I posted in Scott's thread about the possibility of bringing in some 38W x 2 amplifiers built on a TDA7379 IC.  These ones:  http://www.ebay.com/itm/TDA7379-DC-12-18V-Single-Power-Amplifier-Board-Module-Dual-Track-38W-2-2-8-ohm-/382008318673?hash=item58f1785ad1:g:7NQAAOSwTM5Yzjor?

He quoted me R295 for one, but if we order more we can of course get it for cheaper.  I want to finalize ASAP though, so if you want one (or more), just please let me know so that I can chat to Scott!

PS:  If you take one, please commit and pay Scott yourself and arrange your own shipping once it's here.  I'm not going to be handling anyone's money.

Offline PsyCLown

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Re: 38W x 2 stereo amplifiers
« Reply #1 on: March 24, 2017, 04:10:04 PM »
Wait, so R295 for one of those boards only? Or what else is there as on eBay they are selling for R75 each.
Tracked shipping will be an extra $3 so just under R120 with shipping.

Also what would we still need to complete the amp?
AVR: Onkyo HT-R548
Front: B&W DM602 S3 / DIY Full Range Phillips AD12202
Sub: Energy S10.3 / DIY 12"
Headphones: Beyerdynamic DT770 LE & Superlux HD681

A victim of Compulsive Upgrade Disorder (CUD)

Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #2 on: March 25, 2017, 09:12:12 AM »
The majority of the cost goes to shipping and all that, so it'll be drastically reduced if you order more (split shipping and all that).

Also, this is a complete amplifier.  Add power and it's ready to go.

Offline Timber_MG

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Re: 38W x 2 stereo amplifiers
« Reply #3 on: March 25, 2017, 10:23:52 AM »
With Scott the difference is that the wares are brought here by courier, not Post Office.

Offline PsyCLown

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Re: 38W x 2 stereo amplifiers
« Reply #4 on: March 25, 2017, 05:32:59 PM »
With Scott the difference is that the wares are brought here by courier, not Post Office.

Oh I see, so quicker and easier than waiting and dealing with customs and the Post Office.

The majority of the cost goes to shipping and all that, so it'll be drastically reduced if you order more (split shipping and all that).

Also, this is a complete amplifier.  Add power and it's ready to go.
I see, so it takes 12V - 18V power - so I imagine best to use one of those 2-pin type power adapters, not sure where to source a spare one to power this unit though.

How does one go about feeding the audio source to this amp? Via that weird 3-pin connector thing?
Does it perhaps come with an adapter (or could you purchase one) where it would allow you to connect RCA cables at least?
AVR: Onkyo HT-R548
Front: B&W DM602 S3 / DIY Full Range Phillips AD12202
Sub: Energy S10.3 / DIY 12"
Headphones: Beyerdynamic DT770 LE & Superlux HD681

A victim of Compulsive Upgrade Disorder (CUD)

Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #5 on: March 25, 2017, 08:23:24 PM »
R90 with free shipping, you can't be in such a rush that you'd pay 3 times as much just to get it here faster?
http://www.ebay.com/itm/TDA7379-Single-Power-Amplifier-Board-Module-Dual-Track-38W-2-DC-12-18V-/351897639586

Also if you bring in just one unit you probably won't get charged duties/vat, bulk order will attract Vat 15.5% at the very least and probably an extra charge from Scott to get the amp to where ever you are in SA?
Music is in the Mind

Offline Trompie67

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Re: 38W x 2 stereo amplifiers
« Reply #6 on: March 26, 2017, 06:41:48 AM »
R90 with free shipping, you can't be in such a rush that you'd pay 3 times as much just to get it here faster?
http://www.ebay.com/itm/TDA7379-Single-Power-Amplifier-Board-Module-Dual-Track-38W-2-DC-12-18V-/351897639586

Also if you bring in just one unit you probably won't get charged duties/vat, bulk order will attract Vat 15.5% at the very least and probably an extra charge from Scott to get the amp to where ever you are in SA?

Free economy shipping. Which means SAPO. I'd happily pay the extra to ensure shipping, otherwise why not simply flush the R90 down the loo? 3 x more may seem a lot in this instance because the item cost i so low, with more expensive items the shipping costs will not appear as exorbitant!
*Insert profound or witty phrase here*

Offline PsyCLown

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Re: 38W x 2 stereo amplifiers
« Reply #7 on: March 26, 2017, 11:42:50 AM »
Free economy shipping. Which means SAPO. I'd happily pay the extra to ensure shipping, otherwise why not simply flush the R90 down the loo? 3 x more may seem a lot in this instance because the item cost i so low, with more expensive items the shipping costs will not appear as exorbitant!

I personally order tons from China (especially in the past 12 months) and have had very little to no problems.
Purchased phones, vape mods, various electronics and tools and all was shipped via EMS (SAPO).

As long as you get a tracking number, it isn't a problem. Worst case, make sure there is insurance. Majority of eBay sellers will reship or refund for free if it does not arrive after a while.

Custom duties is often very low and cheap, I brought in 2x USB DAC's from eBay which cost me R200 with shipping and paid R36 customs. Took around a month via China Post.

To each their own though.
AVR: Onkyo HT-R548
Front: B&W DM602 S3 / DIY Full Range Phillips AD12202
Sub: Energy S10.3 / DIY 12"
Headphones: Beyerdynamic DT770 LE & Superlux HD681

A victim of Compulsive Upgrade Disorder (CUD)

Offline Skylark

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Re: 38W x 2 stereo amplifiers
« Reply #8 on: March 26, 2017, 01:27:34 PM »
Free economy shipping. Which means SAPO. I'd happily pay the extra to ensure shipping, otherwise why not simply flush the R90 down the loo? 3 x more may seem a lot in this instance because the item cost i so low, with more expensive items the shipping costs will not appear as exorbitant!
That's the point, in this instance it makes no sense to pay for better shipping if the faster shipping triples the price for more expensive items it's a different story. If the item doesn't arrive after 10 weeks you can ask for a refund that you will most definitely get.

I have noticed that after the box up that is Xmas time, intl shipping orders sent from China are coming through reasonably fast and consistently.

I'd gladly pay the R90 and wait it out, if you need it ASAP and it's mission critical that it arrives then definitely use the faster shipping.
Music is in the Mind

Offline ingenieus

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Re: 38W x 2 stereo amplifiers
« Reply #9 on: March 26, 2017, 07:13:07 PM »
I see, so it takes 12V - 18V power - so I imagine best to use one of those 2-pin type power adapters, not sure where to source a spare one to power this unit though.

How does one go about feeding the audio source to this amp? Via that weird 3-pin connector thing?
Does it perhaps come with an adapter (or could you purchase one) where it would allow you to connect RCA cables at least?

An old laptop or printer power supply might do the trick. They can be found in the voltage range specified. Do not exceed 18V or the magic smoke will escape from the chip and it will not work again. Ratings are usually 60 to 100VA but your mileage may vary.

You do indeed have to use the weird 3-pin for input.


Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #10 on: March 27, 2017, 07:14:43 AM »
Laptop PSU's are in the 18.5V range.  The chip on this one handles up to 22VDC, I pulled the spec sheet, so perhaps that'll work.  Otherwise and 12VDC power supply would work, just needs enough oomph to drive it.

Also, that 3-pin connector is the same as you would find on 12V computer fans.  Just pull an old fan, cut off the connector and you're good to go.

Offline PsyCLown

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Re: 38W x 2 stereo amplifiers
« Reply #11 on: March 27, 2017, 08:51:00 AM »
Ahh alright, so old laptop charger then.

Most of the newer fans are now 4 pin if I recall correctly, although I am sure you can still find the older 3 pin ones. Then if you were to take an RCA cable for signal, the main pin in the middle would be the positive and the shielding would be the negative?

What would you need to cool it down, I read it does recommend some form of a heatsink?
AVR: Onkyo HT-R548
Front: B&W DM602 S3 / DIY Full Range Phillips AD12202
Sub: Energy S10.3 / DIY 12"
Headphones: Beyerdynamic DT770 LE & Superlux HD681

A victim of Compulsive Upgrade Disorder (CUD)

Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #12 on: March 27, 2017, 08:58:24 AM »
Ahh alright, so old laptop charger then.

Most of the newer fans are now 4 pin if I recall correctly, although I am sure you can still find the older 3 pin ones. Then if you were to take an RCA cable for signal, the main pin in the middle would be the positive and the shielding would be the negative?

What would you need to cool it down, I read it does recommend some form of a heatsink?

The 4-pin fans you're talking about are PWM (Pulse Width Modulation) controlled fans, and are used almost exclusively on CPU coolers.  Standard case fans are all 3-pin, from the old ones to the newest ones.

Regarding the RCA as input, yes.  You would combine the negative input on the neg (middle) pin and the other two to the outer pins to input stereo.

Regarding the laptop charger - it's a guess of mine that it would work.  I hope it would, since the chip has a max voltage of 22V and a max operating voltage of 20V, so I'm GUESSING a laptop charger would be perfect at 18.5V, but I may be wrong.

Also yes, you would definitely need a heatsink to cool this amplifier.  I'm sitting with a big block heatsink at home that I bought MANY years ago for a different project, and it should be able to cool 3~4 of these chips are the same time easy.  I would recommend you buy a heatsink to cool this with as well, it's not going to last long without a heatsink.

Offline PsyCLown

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Re: 38W x 2 stereo amplifiers
« Reply #13 on: March 27, 2017, 11:11:38 AM »
The 4-pin fans you're talking about are PWM (Pulse Width Modulation) controlled fans, and are used almost exclusively on CPU coolers.  Standard case fans are all 3-pin, from the old ones to the newest ones.

Regarding the RCA as input, yes.  You would combine the negative input on the neg (middle) pin and the other two to the outer pins to input stereo.

Regarding the laptop charger - it's a guess of mine that it would work.  I hope it would, since the chip has a max voltage of 22V and a max operating voltage of 20V, so I'm GUESSING a laptop charger would be perfect at 18.5V, but I may be wrong.

Also yes, you would definitely need a heatsink to cool this amplifier.  I'm sitting with a big block heatsink at home that I bought MANY years ago for a different project, and it should be able to cool 3~4 of these chips are the same time easy.  I would recommend you buy a heatsink to cool this with as well, it's not going to last long without a heatsink.

An old stock Intel CPU heatsink should suffice (without the fan)?

What would be the best way to get the chip to make proper contact with the heatsink and secure it?
Apply some thermal paste between the chip and heatsink then perhaps some no more nails or epoxy putty to hold it in place against the heatsink perhaps?

Also what is the SNR and other specs like on this particular amp for interest sake? I imagine it to be a rather low end, cheapy amp and not something you'd want in your main audio setup.

EDIT: For interest sake, what are you using yours for?
AVR: Onkyo HT-R548
Front: B&W DM602 S3 / DIY Full Range Phillips AD12202
Sub: Energy S10.3 / DIY 12"
Headphones: Beyerdynamic DT770 LE & Superlux HD681

A victim of Compulsive Upgrade Disorder (CUD)

Offline Toxxyc

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Re: 38W x 2 stereo amplifiers
« Reply #14 on: March 27, 2017, 11:32:44 AM »
I don't have one yet...  :P

When it comes to cooling, an old CPU cooler might work, but I'm not sure if it'll dissipate fast enough.  Might want to drill a hole through it to secure the chip with a bolt though, I wouldn't stick it to the sink with epoxy or something like that.  That's asking for trouble...  :P