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Old 9th Jan 2022, 10:15 pm   #1
Whaam68
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Default TDA1524A preamp

I knocked this up in a few sessions over the last couple of weekends from quasar electronics project kit v3100v3. I was looking for a preamp with old school tone controls which this has as well as a “loudness” contour switch. I picked up their matching power supply with TX as it was fairly cheap and convenient. Being able to change the balance of the sound at low volume is really handy for listening in our smallish spare bedroom. I’ve built a few amps and preamps over the years and none have tone controls so I usually gravitate back to one of my vintage solid state amps. The chassis was scratch built from spare ally sheet and bits I already had in the shed/parts bin. It worked perfectly first time, while not “high end” sounds very good to me with just with the Chinese components that came with the kit and seems to drive my old diy 2A3 amp well. It’s silent up to 3/4 on the vol pot and then with no signal there is just a small amount of hiss. I’m pleasantly surprised and enjoyed knocking it up. It comes with well written instructions unlike most eBay kits I’ve bought over the years and can alternatively be powered from a laptop brick. Anyway if anyone is looking for this kind of thing it may be worth a look. Mike
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Old 9th Jan 2022, 10:59 pm   #2
Cruisin Marine
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Default Re: TDA1524A preamp

That is very nice work- well done.
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Old 10th Jan 2022, 2:21 pm   #3
Trevor
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Default Re: TDA1524A preamp

Mike
what does it do is it line level only or does it have phono ?
i have googled the chip most interesting line level only but voltage controlled ?
looks nice
Regards Mike

Last edited by Trevor; 10th Jan 2022 at 2:34 pm.
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Old 10th Jan 2022, 3:06 pm   #4
Whaam68
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Default Re: TDA1524A preamp

Hi Trev
Line level only for this one which is fine for me as no turntable upstairs (home office come hobby come spare bed room). There is a blurb about the circuit on the project page on the quasar electronics site. Project 3100.
Yes it uses voltage control which they say allows the use of cheaper linear single gang pots to keep the cost down.
I need to hook it up to the 405 to compare to the cd input on the 44 but a very good sound through the valve amp.
Best
Mike
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Old 10th Jan 2022, 3:51 pm   #5
Radio Wrangler
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Default Re: TDA1524A preamp

If that is the Philips chip I think it is, it's a good bit less old-school than you may think. The tone controls are implemented as switched-capacitor filters rather than purely analogue like the classic Baxandall circuit. Volume and balance are done by variable gain amplifiers. All control inputs are DC.

There are companion chips with DC controlled input selectors, and later versions with I2C control.

They were aimed at the car audio market, so phono inputs were not included.

They work.

David
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Old 10th Jan 2022, 8:13 pm   #6
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Default Re: TDA1524A preamp

Yup, found it ...
https://quasarelectronics.co.uk/Item...-tone-controls
... and have ordered one

Mike, many thanks for giving us the heads-up.
Best wishes
Guy
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Old 10th Jan 2022, 9:09 pm   #7
Uncle Bulgaria
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Default Re: TDA1524A preamp

That looks really good - and whoever stays in your spare bedroom is rather lucky! A valve amp per guest is probably a good rule of thumb for all of us.
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Old 11th Jan 2022, 11:56 am   #8
Whaam68
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Default Re: TDA1524A preamp

Only me in there unfortunately working all day long so more time looking at it than listening to it :0( Any guests would have to negotiate the piles of boxes and half finished projects.
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