the Pioneer Spec2 still sells top dollar till this day, http://www.ebay.com/itm/PIONEER-STE...ultDomain_0&hash=item1e6d3753ff#ht_542wt_1187
manual here: Pioneer Spec-2 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
into 8 ohms, unloaded rail is actually 91volts, loaded is 75volts......
this is because of the torroid traffo used, finite dc resistances in the windings causes this much rail sags....
and this is what i have been saying all along......voltages alone does not paint the true picture unless it is qualified as unloaded voltage or full power voltage.....
manual here: Pioneer Spec-2 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
into 8 ohms, unloaded rail is actually 91volts, loaded is 75volts......
this is because of the torroid traffo used, finite dc resistances in the windings causes this much rail sags....
and this is what i have been saying all along......voltages alone does not paint the true picture unless it is qualified as unloaded voltage or full power voltage.....
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Yes, measuring voltages at the output tells a lot about an amplifier design and build quality.
Specifying amplifiers by output voltage instead of output power would be much more useful to the consumer (both commercial and domestic) and remove some of the room for dishonesty in advertising and suchlike.
I have no problem with voltages.
I do have a problem with an amplifier that is specified as 200W when it is obviously "flawed" in that output voltage collapses when significant load is placed across the speaker terminals. How on earth are we expected to believe it can drive a reactive load?
As I said "not fit for purpose" !!!
Specifying amplifiers by output voltage instead of output power would be much more useful to the consumer (both commercial and domestic) and remove some of the room for dishonesty in advertising and suchlike.
I have no problem with voltages.
I do have a problem with an amplifier that is specified as 200W when it is obviously "flawed" in that output voltage collapses when significant load is placed across the speaker terminals. How on earth are we expected to believe it can drive a reactive load?
As I said "not fit for purpose" !!!
i have seen a lot of commercial amps before, rails do sag.....
my home built super leach had unloaded rails of +/-83 volts, continuous power testing to output 45volts ac, with both channels driven rails sag to +/-72volts...
mine had an EI traffo with center leg of 2inches stacked to 3 inches.... i used that amp to drive a 4way speaker system that used passive crossovers with chokes and capacitors......
11volts of sag on the PSU when driving rated impedance/resistance to maximum rated power does not meet my standards. Then you have to make a correction for the increased ripple due to the full power current demand and you will probably find that the available voltage from the PSU at it's minimum is 12 to 13V below the quiescent voltage.
If an amplifier sags by 20 or 30V at maximum rated power into rated impedance/resistance then in my opinion it does not meet any Power Amplifier Standard. As I said not fit for purpose.
If an amplifier sags by 20 or 30V at maximum rated power into rated impedance/resistance then in my opinion it does not meet any Power Amplifier Standard. As I said not fit for purpose.
Voltage sag means nothing. You need to report it to the off-load voltage (%) in order to get a real image.
Harman Kardon publishes their receivers specs very clear - this much for two channel driven, this much for all channel driven to account for the real voltage sag.
Any transformer will have that sag. The magnetic core and windings determine the internal resistance. You can calculate the sag if you know the so-called short-circuit impedance (%, smaller is better).
I completely disagree.
It tells me that the amplifier can. or cannot, or somewhere in between, deliver load current. Maybe it doesn't tell you.
It always will sag,but well designed (or chosen) transformer and capacity in PSU will decrease the percentage,is it not like that? If we want "locked" PSU voltage,than we should chose regulated one. Some say that regulated PSU ´s kills dynamic characteristics of an amplifier... I like to keep things as simple as possible,and take transformer with 4 x power of one channel driven by it in a stereo amplifier. It sags at transformer secondary,so question would be: what percentage is tolerable?
a loss of <0.4dB at the speaker terminals when the load is reduced from rated load to half rated load. That would be an excellent result that proves the amplifier can deliver current to resistive loads.
I would settle for <=0.6dB loss for that same test.
1dB loss indicates that the amplifier is starting to struggle delivering current or that the protection scheme is interfering with valid audio signals.
1.5dB is a terrible loss that indicates the amplifier cannot pass the large currents that a reactive speaker can demand.
I would settle for <=0.6dB loss for that same test.
1dB loss indicates that the amplifier is starting to struggle delivering current or that the protection scheme is interfering with valid audio signals.
1.5dB is a terrible loss that indicates the amplifier cannot pass the large currents that a reactive speaker can demand.
you don't seem to know.....show me the standards.....ah, it's your opinion only.....
an ideal power transformer will have zero dc resistance and zero leakage resistance....but such transformer do not exist in real world....it is only in your imagination.....
it looks like you haven't built any transformer and a lot of amps.....then you will know....
I have never built any transformers.
I have modified many transformers.
I have built many Power Amplifiers.
I am starting to get a handle on which parameters in which components lead to some of the sound reproduction qualities.
I have never claimed that an ideal transformer exists in real equipment.
I don't know why you bring in the herring to your argument. It devalues what you have to contribute.
I have modified many transformers.
I have built many Power Amplifiers.
I am starting to get a handle on which parameters in which components lead to some of the sound reproduction qualities.
I have never claimed that an ideal transformer exists in real equipment.
I don't know why you bring in the herring to your argument. It devalues what you have to contribute.
but that is the message you seem to project in your posts.....
real transformers have finite dc resistances and leakage inductance's.....so that when current flows thru its coils there is voltage drop, that is the nature of the beast....
now as to what drop is acceptable or not, i haven't seen any standards, if you know such please post it here....
all i know is that on full power testing for 5 minutes, the amplifier must survive it without getting burned down....
i have asked the question on power transformer size for power amplifiers in forums before, the answer i got that stuck in my head was, "get the biggest transformer that will fin in your box"......
your conclusion is wrong.
For details go back to "my opinion" in post576 and read on.
And to save you calculating/guessing, that's a voltage loss of ~8.55V for the combined PSU and amplifier.
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Quote:
Originally Posted by alex mm View Post
..... Revised PCB this time , much better I hope ....
Hi Mr Apex Sir,
i try this pcb layout #145 but i have problem i got -48vdc at the output using 35 0 35 VAC trafo. I replace bc550 and bc560 to mpsa92/42 and mount in reverse position. sorry i dont have picture of my work. hope you can give me hint/clue on what could be the problem of my work if there is presence of high DC volts on output. thanks in advance.
these are the picture of my work..
SR200 - Photobucket Groups
regards,
nix
Originally Posted by alex mm View Post
..... Revised PCB this time , much better I hope ....
Hi Mr Apex Sir,
i try this pcb layout #145 but i have problem i got -48vdc at the output using 35 0 35 VAC trafo. I replace bc550 and bc560 to mpsa92/42 and mount in reverse position. sorry i dont have picture of my work. hope you can give me hint/clue on what could be the problem of my work if there is presence of high DC volts on output. thanks in advance.
these are the picture of my work..
SR200 - Photobucket Groups
regards,
nix