| lawka |
Anyone can help to advise the selection of Transformer rating of above item.
Sometimes, the manuals of High End components always indicated likely 100 W at 8£[, 200 W at 4£[ & 400 W at 2£[. It supposed that the power rating of transformer would lead to the end result?
Someone use the 1000 VA for single chanel but I heard most people to choose >=1300 VA. Could anyone advise the caluation to formulate the final result. |
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| JasonL |
| Im using a single 1000 va Victoria Magnetics Toroidal per Aleph 2 Mono Block. |
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| wuffwaff |
| quote: | Originally posted by lawka
Sometimes, the manuals of High End components always indicated likely 100 W at 8£[, 200 W at 4£[ & 400 W at 2£[. It supposed that the power rating of transformer would lead to the end result?
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well it does help but in the first place the amp must be able to double it´s power output when you halve the load. This is only possible if the output current doubles. With an Aleph (X or not) the max. output current is a function of the bias and the ac-current gain. Normally you can´t get more than twice the bias as peak output current.
william |
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| trigon |
I have used 1500W for each channel in my Aleph 4s.
Very relaxed and efortless soundwise, meaning good.
Trigon |
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| jrsun |
Trigon
Where did you get them ?
What is the secondary voltage?
Thanks ! |
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| Alain Dupont |
On the PassLab site, go to
http://www.passdiy.com/gallery/aleph2-p1.htm
You have 3 projects on Aleph 2
1)- Use Toroids 1,5kW 33+33V per channel
2)- Use a 1KVA, 35-0-35 transformer with shielding from Victoria Magnetics. per channel
3)- Used Plitron 1000VA toroids with 33+33V secondaries, this gives about 46 VDC on the power rails per monobloc
Merry X-mas to all...
Alain.:xmastree: |
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| moe29 |
Check out my Aleph 2: LINK
If you build a CLC power supply - Get a transformer with 37v secondaries.
Not hard to get exspecially if you are having one built by Victoria Magnetics.
With a CL-60 thermistor on the mains for inrush protection, this
will give you 45 volt rails. :) |
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| trigon |
| quote: | Originally posted by jrsun
Trigon
Where did you get them ?
What is the secondary voltage?
Thanks ! |
Hi jrsun
I've got them from Plitron and they are with ground wire and with shieldind cage as well. Primaries are 2 x 100 and 120 and secondaries are 2 x 40V before rectifier.
Here is the pic. and link of my Aleph 4
Trigon |
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| moe29 |
dang... Trigon's LINK is better than mine:rolleyes:
that is one serious Aleph (as mentioned in the thread)
should be in the PassDiy Gallery |
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| jrsun |
One more silly question,
Let's say if I decide to go 1.5KVA transformer, what is the difference among different secondary voltage 35V, or 37V or 40V ?
1. different bias current with same resistor or
2. same bias current with different resistor or
3. different bias current and different resistor or
4. none of the above |
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| jrsun |
One more silly question,
Let's say if I decide to go 1.5KVA transformer, what is the difference among different secondary voltage 35V, or 37V or 40V ?
1. different bias current with same resistor or
2. same bias current with different resistor or
3. different bias current and different resistor or
4. none of the above |
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| GRollins |
If I'm reading your post correctly, the answer is that a transformer with a higher voltage rating will give you a higher rail voltage. The bias will be pretty much the same. You'll end up with higher output wattage, at least until the amp current limits, and the output devices will run hotter. Plan accordingly regarding heatsinks.
Assuming that you're shooting for an Aleph 2, the 35V transformer will be closest to the original. Actually, you can even go a volt or two lower. A 33V transformer will do admirably.
For what it's worth, I used 1kVA Plitrons for one pair of my Aleph 2s, and surplus 1kVA I ordered off the web for the other pair. You can argue that higher current transformers sound better or whatnot, but as regards to the load on the transformers, I regard 1kVA transformers as pretty much overkill for a 300W (idle) circuit. Both sets of transformers get warm, but only just. You could easily do the job with a 600VA transformer per channel for Aleph 2s. For that matter, you could probably go as low as 500VA as long as you make sure that you have plenty of air circulating--perhaps even a fan, though the transformer will definitely be warm to the touch.
Grey |
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| Brian Donaldson |
Rail voltage is very flexible with the Aleph. The only concern is heat sink on the output fets. If you have 4 ohm speakers, go with the lower rails and up the bias. If you have 8 ohm speakers and want the extra few watts, go larger. My Aleph2+ works fine anywhere from +- 25 v to +- 65 volts. sink temp is the only limit.
Start with a pot for R19. Decreasing the resistance decreases the bias. You can toy around with this and run as much bias as your heat sinks will allow.
Best thing might be to shoot for 5 to 10 volts too many, play whith the bias to find what the sinks can safely handle and figure the resistance to dump the excess voltage in a CRC psu. One thing I found is it is much easyer to dump 10V than to Gain 10V. |
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| lawka |
I just query how to get the performance of the listed specification of the High End product likely. Double the output watt while the speaker impedance dropped from 8 ohm to 4 ohm. Is it possible to adopt a larger rating of transformer or any other suggestions.
Thanks |
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| BobEllis |
a larger transformer will be a by product, but not sufficient to cause this to bappen. Larger heat sinks will be another by product.
To enable the power to double as the load drops from 8 to 4 ohms you'll need to boost the idle current by 1.4 x, while keeping the voltage sufficient for 8 ohm operation. this increases your idle dissipation.
So, if you have the heat sinks for 450 watts or so, go for it. |
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| lawka |
Thank you, I got it.
High voltage + large area Heat Sink. Capable of double the current. |
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