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Old 8th May 2007, 10:26 PM   #561
massimo is offline massimo  Italy
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You must consider that rectifiers have an internal resistance that cause a drop and being the resistance almost costant, the higher the current the higher the voltage drop. Consider also that different rectifiers have different internal resistance. Hi speed dicrete diodes have better efficency (read: lower internal resistance)
Secondly, not all transformers behave the same. The best ones are "stiff" enough not to drop the voltage when the load is absorbing huge currents (and Class A amps are very demanding).
In other words, the lower the transformer regulation (%), the lower the difference between the voltage with no load and when delivering the rated (max) current (and Class A amps are absorbing the max current all the time).
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Old 8th May 2007, 11:14 PM   #562
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Actually, the voltage drop in the rectifier is not resistive in nature--it's built-in to the nature of a PN junction; about .65V or so, regardless of current drawn through the diode.

Grey
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Old 8th May 2007, 11:26 PM   #563
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I saw this crossover on page 5 of the the F4 pdf file and wondered what it would take to implement it. Can the x-over values be deduced from standard speaker x-over software?

Has anyone experimented with this concept.

I know I will...
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File Type: gif passive x-over between pre and power amp.gif (17.7 KB, 1105 views)
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Old 8th May 2007, 11:30 PM   #564
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by carpenter
I saw this crossover on page 5 of the the F4 pdf file and wondered what it would take to implement it. Can the x-over values be deduced from standard speaker x-over software?

Has anyone experimented with this concept.

I know I will...

have you djvu reader?

if yes,just say............
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Old 8th May 2007, 11:39 PM   #565
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I could have used this design 25 years ago when I was first getting into x-overs. I used to split the pre signal into several power amps and then feed the x-over. How interesting to feed the passive x-over before the power amp! I wish I would have known that, then.

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Old 8th May 2007, 11:41 PM   #566
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passive seems cleaner, more pure......... maybe I'm full of it, but I like the concept.
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Old 9th May 2007, 12:00 AM   #567
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Quote:
Originally posted by jleaman



I definatly agree, i just connected my fluke meter back from calibration and i checked our AC wall voltage of 122, then looked at my Alephs that i have now,

Inside is a 300Va with 16V secondary with calculations it should have rail voltages of

16 * 1.4 = 22.4V rails BUT when measuring them i see 20.1V so the voltage is a little dropped i guess.

So i think ill be ordering 2 of these 18-0-18's and use that.

Thanks for your help massimo.

Jase
I have that exact toroid in my F4 and 122V out of my wall as well. I posted a few pages back that I was measuring 26.5V after rectification, but that number dropped to about 23V after the amps were connected.

I thought about getting more anteks, but Plitron is local for me, so even though I have to pay 2 taxes, I would get 2 300VA 18V toroids instead. After shipping, duty and exchange, the price works out to be close and the plitrons are potted, so they are a bit easier to mount (and they're not as tall).
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Old 9th May 2007, 02:47 AM   #568
jleaman is offline jleaman  Belgium
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Quote:
Originally posted by twitchie


I have that exact toroid in my F4 and 122V out of my wall as well. I posted a few pages back that I was measuring 26.5V after rectification, but that number dropped to about 23V after the amps were connected.

I thought about getting more anteks, but Plitron is local for me, so even though I have to pay 2 taxes, I would get 2 300VA 18V toroids instead. After shipping, duty and exchange, the price works out to be close and the plitrons are potted, so they are a bit easier to mount (and they're not as tall).

Plitrons are really expensive, i can't afford thos. If i could id order potted ones also or just one but 800va one for a stereo F4. i'm going the single psu per channel tho.

as to carpender's post im doing this exactly

Already started last week on the active xovers boards that were designed are etched and on there way.



J'
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Old 9th May 2007, 02:51 AM   #569
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Quote:
Originally posted by jleaman



as to carpender's post im doing this exactly

Already started last week on the active xovers boards that were designed are etched and on there way.



J'
My idea is to configure a "passive"--not active--x-over before the power amps. I already have an active x-over manufactured by TDM. It sounds like you're doing the active route. Yes?

If you're doing the passive thing, tell me how it's treating you. Thanks.


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Old 9th May 2007, 03:48 AM   #570
herm is offline herm  United States
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Carpenter,

Look here for passive Line-level crossover stuff....

Planet 10's tech articles

herm
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