Lets say you guys recommend a 24V transformer for a GC. At Parts Express they sell a 25V torrid...now heres the question...in order to hook up a stereo pair of GC circuits do I hook them both up to the same output wires, or are there mulitple taps comming off of the transformer that each have 25V?
And also can I power both chips off of one 25V supply, so long as they, collectevly, don't draw more current than the supply can handle (3A or 5A in the case of these torrids).
Also would one of the Velleman PS kits such as the one Parts Express sells that has 1.5-35V @ 1A be suitable to power a GC...using one PS per channel. I don't know how much current a Gain Clone draws so I didn't know if that was a powerfull enough supply.
Sorry for the Noob questions....maybe there are others that watch this forum that don't know this stuff too.
And also can I power both chips off of one 25V supply, so long as they, collectevly, don't draw more current than the supply can handle (3A or 5A in the case of these torrids).
Also would one of the Velleman PS kits such as the one Parts Express sells that has 1.5-35V @ 1A be suitable to power a GC...using one PS per channel. I don't know how much current a Gain Clone draws so I didn't know if that was a powerfull enough supply.
Sorry for the Noob questions....maybe there are others that watch this forum that don't know this stuff too.
Let me give a somewhat generic answer. Some people will use a transformer with a single secondary (centertapped assumed) to make a single bipolar supply, then use it to drive both channels. Some people will use a transformer with dual secondaries (each ct) to make two sets of bipolar supplies and run one to each channel separately. Or even use two separate transformers to make separate supplies for each channel. All of these schemes will work, at various cost and performance levels.
Is this what you're asking?
Is this what you're asking?
Hybrid fourdoor,
Nuuk site answers the technical side of your questions very nicely, but can I add:
1. I don't think you need the Velleman PS kit. The PS for a GC can be as simple as a transformer and a bridge rectifier or 4 (or 8) diodes. (and fuses ARE required on the primary at least)
2. 25V could be reaching the max recommended voltage. I am currently running my GC from a single 12-0-12 300VA toroid and I was absolutely shocked at the volume generated by these little buggers considering my speakers are very inefficient. (85dB I think)
3. You will find a lot of conflicting opinions, so sometimes it is just better to try it for yourself.
Nuuk site answers the technical side of your questions very nicely, but can I add:
1. I don't think you need the Velleman PS kit. The PS for a GC can be as simple as a transformer and a bridge rectifier or 4 (or 8) diodes. (and fuses ARE required on the primary at least)
2. 25V could be reaching the max recommended voltage. I am currently running my GC from a single 12-0-12 300VA toroid and I was absolutely shocked at the volume generated by these little buggers considering my speakers are very inefficient. (85dB I think)
3. You will find a lot of conflicting opinions, so sometimes it is just better to try it for yourself.
I purchased a 25-0-25 toroid in my gainclone project. I decided to go near the top of the documented supply voltage range so I could get the most power out of it...but it was suggested to me that the chips will generate a fair bit of heat when being supplied that high.
I'm going to try it with the modest heatsinks I have. If it runs too hot, I may try dropping the voltage using diodes in series with the power supply. Each one in series with the power supply drops the voltage by about 0.7 volts. Two diodes in series with each rail should bring it down to about the voltage you would get using a 24-0-24 unit. I would locate these diodes in the power supply enclosure, away from the chips.
I'm not sure if adding diodes in series with the power supply rails will cause any sonic degradation. Perhaps someone could comment on that?
If it does end up sounding bad then I will probably build another amp with this transformer and get a lower voltage one for my LM3875 gainclone. I've read about good results with an 18-0-18 tranny.
Good luck!
I'm going to try it with the modest heatsinks I have. If it runs too hot, I may try dropping the voltage using diodes in series with the power supply. Each one in series with the power supply drops the voltage by about 0.7 volts. Two diodes in series with each rail should bring it down to about the voltage you would get using a 24-0-24 unit. I would locate these diodes in the power supply enclosure, away from the chips.
I'm not sure if adding diodes in series with the power supply rails will cause any sonic degradation. Perhaps someone could comment on that?
If it does end up sounding bad then I will probably build another amp with this transformer and get a lower voltage one for my LM3875 gainclone. I've read about good results with an 18-0-18 tranny.
Good luck!
S.C said:What is the effect on sound when we using One PS or Two PSs to power two channels?
Expect the following advantages by giving each channel it's own power supply...
1) You'll get far less crosstalk / intermodulation between the 2 channels (PSRR with these chips it quite high so that's probably not a major point but it never hurts)
2) Assuming that you dont skimp on power supply rating, you'll get less voltage sag under load by using individual power supplies and so you'll get closer to rated power output for a given rail voltage.
grege said:
And of course, dont forget about the filter capacitors.
moamps
Your example does not apply to the typical gainclone referred to in these forums but even if we accept that a person intends to build a single chip 100W for an 8 ohm speaker, I would not listen to anything that would draw a sustained 100W from this Class B amp
Most people use transformers that are too big for gainclones and IMHO probably degrade the sonics by doing so. Bigger is not always better.
Your example does not apply to the typical gainclone referred to in these forums but even if we accept that a person intends to build a single chip 100W for an 8 ohm speaker, I would not listen to anything that would draw a sustained 100W from this Class B amp
Most people use transformers that are too big for gainclones and IMHO probably degrade the sonics by doing so. Bigger is not always better.
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