Gainclone on +/- 12V PSU

[Rocky]

How many watts will I be able to get out of a LM1875 or LM3875 gainclone when powering it with +/- 12V (300VA)?

I am building a speaker system (dipole midbass, horn midhighs) with high sensitivity drivers (97dB/W/m and higher) and need active filters.. 24dB/oct LR..

The plan is to get tube amplifiers (2A3 SET or alike) to drive the speakers in the future, but for now it would be great to have 4 channels of gainclone power built in to the filter, utilizing the filter's +/- 12V PSU... I will not need more than 2W from each clone.. Will the chips be able to deliver this at +/- 12V?

Also, how will the chips heat at such a moderate power? Will I need heatsinks, or can I just bolt them to the alu chassie?

[peranders]

http://www.national.com/appinfo/audi...gn_Guide13.xls
http://www.national.com/appinfo/audi...sign_Guide.pdf

Check this file!

You need 2 watts and you plan to use 300 VA transformer?

May I ask what kind of speakers you have and also how high volume you want?

With a "normal" speaker you will get 90-96 dB at 1 m, meaning 80-90 dB in the room. This is not much I would say.

I suggest that you get a 2 x 24-28 VAC/150-300 VA transformer.

According to spreadsheet you will get 5-6 W and with so low power supply voltage you can mount the IC's directly into chassis.

[joensd]

How many watts will I be able to get out of a LM1875 or LM3875 gainclone when powering it with +/- 12V (300VA)?

That will depend on your speaker load.
You can plug yout numbers into this calculation tool.

The plan is to get tube amplifiers (2A3 SET or alike) to drive the speakers in the future, but for now it would be great to have 4 channels of gainclone power built in to the filter, utilizing the filter's +/- 12V PSU... I will not need more than 2W from each clone.. Will the chips be able to deliver this at +/- 12V?

Yes. For exact figures see above.

Also, how will the chips heat at such a moderate power? Will I need heatsinks, or can I just bolt them to the alu chassie?

If the chassis is thicker than 2mm it most probably will be enough at the power levels you are talking about.

Cheers
Jens

[Rocky]

Originally posted by peranders
You need 2 watts and you plan to use 300 VA transformer?

That is correct.

Originally posted by peranders
May I ask what kind of speakers you have and also how high volume you want?

With a "normal" speaker you will get 90-96 dB at 1 m, meaning 80-90 dB in the room. This is not much I would say.

The Supravox 215 GMF midwoofer is rated 97dB/W/m, the TAD 4001 on the horn is rated around 111dB/W/m but I suspect it's actually louder mounted on my round tractrix horn. Both is 8 ohms steady load.

Originally posted by peranders
I suggest that you get a 2 x 24-28 VAC/150-300 VA transformer.

Out of the question. I'm reluctant even to spend on chips and caps/resistors for the chipamp. My funds goes into tube projects and speakers at the moment, so the chips will have to use my +/- 12V that is already in use in the active filter, or there will be no chips. This is only ment to be a short term solution while awaiting funds for completing my SET tube projects.

Originally posted by peranders
According to spreadsheet you will get 5-6 W and with so low power supply voltage you can mount the IC's directly into chassis.

Thanks. Thoose watts will keep me running for a long time.

[Rocky]

Originally posted by joensd

That will depend on your speaker load.
You can plug yout numbers into this calculation tool.

Thanks

Originally posted by joensd

If the chassis is thicker than 2mm it most probably will be enough at the power levels you are talking about.

Thanks