hi,
should i use a 50 or 28v+- transformer for the "Figure 1 - Basic Amplifier Schematic" setup?
would a 50v 300VA be too powerfull?
would a 28v 300VA be too weak?
http://sound.westhost.com/project68.htm
thanks
should i use a 50 or 28v+- transformer for the "Figure 1 - Basic Amplifier Schematic" setup?
would a 50v 300VA be too powerfull?
would a 28v 300VA be too weak?
http://sound.westhost.com/project68.htm
thanks
the problem is that the site im ordering all my parts from doesn't have anything between 2*28v and 2*50v. are both of them so "unadvicable" (what can i say, im norwegian) that i should rather pay the extra bucks (shipping and stuff) for a for example 2*40v? i'm just wondering if the circuit can take 2*40v without overheating or anything.
thanks for the help
) that i should rather pay the extra bucks (shipping and stuff) for a for example 2*40v? i'm just wondering if the circuit can take 2*40v without overheating or anything.thanks for the help
What type of transformer can you get?? If you could get a 2 x 24v AC transformer you will get 28v DC or more after rectification and Voltage drop.....
If you can get Two 2X18v Transformers then you could wire them up so each Transformer gives you 36v AC which will give you your +/-40v DC after rectification.....
Just a couple work around options in case you can not get the exact transformer you need....
Cheers
If you can get Two 2X18v Transformers then you could wire them up so each Transformer gives you 36v AC which will give you your +/-40v DC after rectification.....
Just a couple work around options in case you can not get the exact transformer you need....
Cheers
I am in the process of constructing a P68 using the 1 1/2 board ie. 500 watt and it requires the 50-0-50. I purchased a 50-0-50 @ 800VA off of ebay. Are you building the hipower version? The 1-board version has a recommended 40-0-40 @ 300VA or up to 50-0-50@at least 300VA and a big heatsink. Check out http://stores.ebay.com/Antek-inc_W0QQcolZ4QQdirZ1QQfsubZ0QQftidZ2QQtZkm
I mean a BIG HEATSINK!
I mean a BIG HEATSINK!
Attachments
Hi skogs,
28-0-28Vac will give about +-41Vdc on no load and fall a bit lower when the output stage is biassed to final level.
35-0-35 about +-50Vdc.
40-0-40 about +-58Vdc.
45-0-45 about +-66Vdc.
What voltage does your amp need to produce 300W into what load impedance?
Now you can just about get away with 300VA for a 300W amplifier but I recommend you adopt the usual 1.5times maximum output power 300W use 450VA.
What kind of music do you listen to?
How loud do you listen?
Do you ever host a party with loud music?
Would you loan out your amp for PA duty?
These will ALL affect the heatsink size.
The lower the duty the less heatsink you can get away with.
Ask it to produce close to full power all night and 0.6C/W will overheat.
28-0-28Vac will give about +-41Vdc on no load and fall a bit lower when the output stage is biassed to final level.
35-0-35 about +-50Vdc.
40-0-40 about +-58Vdc.
45-0-45 about +-66Vdc.
What voltage does your amp need to produce 300W into what load impedance?
Now you can just about get away with 300VA for a 300W amplifier but I recommend you adopt the usual 1.5times maximum output power 300W use 450VA.
What kind of music do you listen to?
How loud do you listen?
Do you ever host a party with loud music?
Would you loan out your amp for PA duty?
These will ALL affect the heatsink size.
The lower the duty the less heatsink you can get away with.
Ask it to produce close to full power all night and 0.6C/W will overheat.
thanks a lot andrew!
the ting is that it's recommended a 40-0-40V @ 300VA transformatorer for about 250wrms into 4 ohms. i just wondered if the curcuit could handle 50-0-50V @ 300VA instead, without making any further improvements to it. or would this lead to overheat, distortion or anything?
the amp is going to be used for a subwoofer, 4 ohm. i will use it for HT and some varied music, from rammstein to bright eyes not very loud for long periods. so i'll just go for the 0,6C/W heatsink, and maybe mount a thermo-fan if the heatsink tends to get really hot.
the ting is that it's recommended a 40-0-40V @ 300VA transformatorer for about 250wrms into 4 ohms. i just wondered if the curcuit could handle 50-0-50V @ 300VA instead, without making any further improvements to it. or would this lead to overheat, distortion or anything?
the amp is going to be used for a subwoofer, 4 ohm. i will use it for HT and some varied music, from rammstein to bright eyes
not very loud for long periods. so i'll just go for the 0,6C/W heatsink, and maybe mount a thermo-fan if the heatsink tends to get really hot.Hi,
50-0-50Vac is an enormous jump in voltage into an amplifier.
PSU rails @ +-73Vdc.
Your output stage will be very severely stressed trying to work with this supply voltage.
It is effectively a different amplifier, due to all the SOA calculations having to be redone.
The output power will jump to about 500W but the voltage from the transformer will collapse very quickly and then start clipping the bass signal, sounding absolutely terrible.
For a good bass amp the PSU should be very stiff to hold up while sustained high voltage signals are driven into the bass driver.
Have a rethink, or do the extensive calculations carefully.
50-0-50Vac is an enormous jump in voltage into an amplifier.
PSU rails @ +-73Vdc.
Your output stage will be very severely stressed trying to work with this supply voltage.
It is effectively a different amplifier, due to all the SOA calculations having to be redone.
The output power will jump to about 500W but the voltage from the transformer will collapse very quickly and then start clipping the bass signal, sounding absolutely terrible.
For a good bass amp the PSU should be very stiff to hold up while sustained high voltage signals are driven into the bass driver.
Have a rethink, or do the extensive calculations carefully.
I'm busy bulding one too. 50-0-50 AC is really running things to the limit! You are not leaving much room for ac fluctuations. Elliot states that you shouldn't run it above 70Vpk and he was quite adamant about it and in your circuit you will have almost 71V at no load. Also, if you driving 4 ohm, you should take the 1 1/2 amp route, meaning you should add another 2 pairs of OP devices. This is also quite important! Have a look at the trafo you plan on using. If it's a toroid, it might serve you well to take a couple of windings off to drop the voltage with about 5V or so.
Cheers
Gert
Cheers
Gert
The sink is cannabalized from a 36vdc forklift battery charger.It also just happens to be the correct physical size for the sub box I have selected. One big plate-amp utilizing elliots 10 output P-68 , 8-band sub-woof equaliser P-84,P-38 signal detection circuit and several other supporting projects P-05,P-48 & P-23. The Woofer will be partsexpresse's 15" Titanic driver and its corresponding cabinet. As for the heatsink missing fins , Hmmm , I would,nt be surprise if a certain canadian moderator stole them. He does that @#$% all the time .Ya gotta watch him. LOL ...Well here in the states its Thanksgiving Holiday and I have to go cook a butterball and tune in a real football game in HDTV..
Cheers Dave
Cheers Dave
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