Replacing a pair of TDA2030 to increase power

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Originally Posted by pacificblue

The LM3875 has a bigger surface to attach the heatsink to, so lower thermal resistance. It would get away with a smaller heatsink than the LM1875.

You need a transformer with a power rating in VA that is at least as high as the output power you expect. How much you need to oversize it, depends on
- how often you use the full power and for how long.
- how big your power supply capacitance is.
- how well the transformer is cooled by air-flow.
- how much voltage sag you can accept.
- how much space you have for the transformer.
- how much money you want to spend.
- etc.

If you use 6 dB filters the midwoofer will suffer more. The basic schematic of the 12 dB filter is okay. It is however not as simple as calculating one high-pass and one low-pass with the same filter frequency and the same Q-factor. That is only a starting point.
The filter has to take the actual frequency response into account to achieve a flat response. You may need different filter frequencies and may have to shape the roll-off (and phase) with the Q-factor to make the drivers fit.

I assumed since I would be generating more power with the pair of 3875 I would need a bigger heatsink too since the ratio of electrical power to heat is about the same for almost all Class AB amps.

With the 3875 pair I am looking at 80W rms @ 8ohms, with the 1875 I am looking at 20W rms @ 4 ohms per channel. So a Total of 120W rms. I figured that a 300VA transformer will work.

The transformer like in most amplifiers will be inside a box so there will be no ventiallation as such.

Assuming I am using Wavecor drivers both the 2.75" fullrange and 7 "subwoofer" are fairly flat at about 150hz. However given the limited Xmax and Sd of the fullrange I do agree that I would consider as high a turnover point as sensible. My original plan was to use a pair of Tangband 871 mated to a Morel MW165/166 woofer I was expecting to get from a friend but now the Wavecor drivers look more available.

The inspiration for this are the docks made by Kicker, Vita R4, Vers 2x, Boston Duo+, Intempo, Tivoli, Teac's new SR100 etc..

Vita Audio R4 integrated music system
Vers 2X - Hand-crafted Sound Systems for iPod
http://www.bostonacoustics.com/PDFs/...plus_hires.pdf
Intempo Digital
Tivoli Audio, LLC - iYiYi® Stereo System Generation 2 in Black/Silver
Amazon.com: First Act DK1000 Stereo Docking Station for iPod: Musical Instruments: Reviews, Prices & more

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This is the heatsink I intend to use for each 3875 (the heatsink is twice the size for a pair of bridged 3875)

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I could not find the 3875 locally but I did manage to get a PCB for the 3876 and build a stereo pair of 3876 based on ESP's Project 19 PCB.
Single Chip 50W Stereo Amplifier

The problem now is to bridge the 2 amps.

I am building a +/- 24V DC and a pair of 1875 based on ESP's Project 72 over the weekend.
Single Chip 25W Amplifier (Project 72)

Next might be Project 88 (2132 based preamp) High Quality Audio Preamp or Project 97 Hi-Fi Preamplifier for a preamp.

Since this is for my son a preamp with tone controls might be more fun.