DCDC converters

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   Just ordered one of these:
https://www.soundimports.eu/en/4x100w-tda7498-class-d-amplifier-board.html

Any ideas on what DCDC coverter to get and where from? Don't want to wait 4 weeks from China really.

Also does anyone know the basic theory of what the output of the amplifier will be with different input voltages?

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mstep77 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 19 July 2006 Status: Offline Points: 457	Post Options Post Reply Quote mstep77 Report Post Thanks(0) Quote Reply Topic: DCDC converters Posted: 04 September 2017 at 6:57pm
	Just ordered one of these: https://www.soundimports.eu/en/4x100w-tda7498-class-d-amplifier-board.html Any ideas on what DCDC coverter to get and where from? Don't want to wait 4 weeks from China really. Also does anyone know the basic theory of what the output of the amplifier will be with different input voltages?

slaz Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713	Post Options Post Reply Quote slaz Report Post Thanks(0) Quote Reply Posted: 05 September 2017 at 11:11am
	ISTR Sure make (or made) DC-DC converter boards. IMHO Sure Electronics stuff is somewhat better quality than much of the very cheap Chinese stuff (typically chip-amp boards). They use better quality components and rate things a bit more conservatively .... although some of their specs are still less than complete, and sometimes ambiguous - especially wrt maximum supply rails for chip-amp modules. If a board says e.g. 2 x 100W @ 32V rail, I'd say use 28-29 V ..... you'll get mebbe 80W or so, but better reliability. Watch out for large switch-on inrush currents and nasty switch-on thumps with the DC-DC boards unless you can design, build, and test soft-start circuits .... easier said than done. AFAIK o/p will vary with DC rail pretty much according to Ohm's Law. Edited by slaz - 05 September 2017 at 11:29am
	REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON

studio45 Members Profile Send Private Message Find Members Posts Add to Buddy List Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3864	Post Options Post Reply Quote studio45 Report Post Thanks(0) Quote Reply Posted: 06 September 2017 at 4:22pm
	+1 for the Sure boost converter boards. You will get them in about 2 weeks, or I think they have an express shipping option that only takes about 5 days. They are very well built, have fuses and fan on board, and are designed with audio in mind, so there is extensive filtering and the output rail is a quiet as a mouse. Some cheaper converters leave a lot of switching noise on the rail, which your amp may or may not be able to reject. One thing I have recently put together is three cheap Tusotek 5 amp converters, with their outputs paralleled using a 2N3055 current mirror, to form a 15A converter. It seems to work well powering my low voltage audio gear, and was very cheap. And, of course, I could keep paralleling modules and end up with very high current capability indeed. As for the output power, well I usually do the Ohms Law calculation I=V/R, then P=IV where R is your speaker impedance - and then multiply by 0.8 to account for 80% efficiency. (That is probably a bit optimistic and 70% would be more like it). These Class D modules can swing the chip's output very nearly "rail to rail", but some power is then lost in the output filters, so the speaker voltage is a little lower.
	Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA

mstep77 Members Profile Send Private Message Find Members Posts Add to Buddy List Registered User Joined: 19 July 2006 Status: Offline Points: 457	Post Options Post Reply Quote mstep77 Report Post Thanks(0) Quote Reply Posted: 07 September 2017 at 8:05pm
	Ok nice one, thanks for the replies, just going to get the 500W from the Sure website. The drivers aren't coming for a while so it's not a big deal. Will put up some build pics in a month or two.