Balanced F5 monoblock?
Sorry for asking a question that may have been answered before, but after spending a few weeks reading 2800 odd posts about the F4 I am a bit fuzzy. I should also explain that I have very little electronics knowledge or experience.
The F4 has the option of running it as a balanced monoblock. + and - go to input L+ and R+ and speaker connects to output L+ and R+.
I had a look at the F5 schematic (F5 manual) and wondered if there is any reason not to try the same with the F5. It is interesting BTW that the FW F4 does have this option, but the FW F5 does not. Perhaps that answers my question, but then again there could also be commercial reasons not to offer this option on a "normal" amp like the F5 (opposed to a 0 gain F4).
Some of you must have thought about and tried this option. What was it like?
Thanks,
Albert
Sorry for asking a question that may have been answered before, but after spending a few weeks reading 2800 odd posts about the F4 I am a bit fuzzy. I should also explain that I have very little electronics knowledge or experience.
The F4 has the option of running it as a balanced monoblock. + and - go to input L+ and R+ and speaker connects to output L+ and R+.
I had a look at the F5 schematic (F5 manual) and wondered if there is any reason not to try the same with the F5. It is interesting BTW that the FW F4 does have this option, but the FW F5 does not. Perhaps that answers my question, but then again there could also be commercial reasons not to offer this option on a "normal" amp like the F5 (opposed to a 0 gain F4).
Some of you must have thought about and tried this option. What was it like?
Thanks,
Albert
If I understand correctly, the F5X is better that using a stock F5 as a balanced monoblock (F5X is designed as a balanced monoblock; better than a bridging option for a single ended stereo amp), but my (lack of) knowledge of electronics means the discussions are beyond my comprehension. I would not feel comfortable starting on an F5X at all.
So I go back to my original question. As I am afraid that a stock F5 will probably not be enough to drive Magnepan MGIIIa's, is it an option to build 2 and use them as balanced/bridged monoblocks? Or is the design such that the "F5 magic" is lost when two channels are bridged?
Thank you all for beeing so helpfull.
I presume that the Capacitor on the primary side is still called C9 in the 240v version. As i understand the schematic C9 is 15000uF 25V is that correct ?
A further why is the thermistore in series on the 240V primary side and not as on the 12ov version ?
I presume that the Capacitor on the primary side is still called C9 in the 240v version. As i understand the schematic C9 is 15000uF 25V is that correct ?
A further why is the thermistore in series on the 240V primary side and not as on the 12ov version ?
C9 on the FirstWatt power supply schematic is a 0.0033uf mains voltage capacitor.
Ithink something like this is a better option for soft starting.
http://avondaleaudio.com/soft-start-module/
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The Maggie IIIa is both low impedance and low efficiency, a bridged F5 likely is not enough either.
Leaves the third option.
last i knew user cviller http://www.diyaudio.com/forums/members/cviller.html still had some available . and....... he lives in Denmark
cheers Woody
Sorry Jacco, I am not sure I understand what you are trying to tell me. I think you are telling me that my original idea
is possible?
To clarify, I refer to the following (F4 manual):
Would this work on an F5?
If so, what would it sound like? Could it drive my MGIIIa's mid/high panels?
Thanks,
Albert
If I understand your comment, above, are you planning on putting a 25V capacitor across the primary windings of the power transformer--where the capacitor (and an electrolytic, at that....) will be exposed to your full mains voltage??? If I read that right, I really, really want to caution you about the voltages (lethal) that you are coping with. Any low-voltage electrolytic exposed with full mains voltage will (almost certainly) explode, with resulting damage to the PSU, amp, and perhaps the constructor. An F5 PSU can be a dangerous thing--if at all possible, I recommend you have an EXPERIENCED constructor work with you, and to double-check all your work..... or "subcontract it out" to them. The F5 amp club is a relatively small and select bunch--and we do not want to diminish the club population by one body....!!
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As for the thermistor in series with the 240V primary side--the CL-60 thermistors are used to limit "in-rush" current into the transformer under initial start-up. For that reason, the CL-60 is placed in series, to serve as a temperature-dependent variable resistor (higher resistance when cold; lower resistance when the warm up). The KEY THING is to have a CL-60 on EACH primary winding:
1. When wired for 240V, you place the TWO primary windings and ONE CL-60 all in series. (In effect, you only have ONE primary winding, and therefore need only ONE CL-60.)
2. When wired for 120, you place EACH primary winding in series with ITS OWN CL-60, and then wire the two pairs of windings/CL-60s in PARALLEL. (In effect, you have TWO primary winding and therefore need TWO CL-60s--one for each primary winding).
Both of the two variants are depicted in the FW schematic for the F5 amp. Very straightforward, actually.
Be careful. These power supplies can kill you.
Building a hefty power supply
The following link had been posted on the diyaudio "Class D" amp forum about two years ago, and steers you to a good overview of power supply construction. Credit goes to the "Decible Dungeon" for the article.
Although it references construction for a Class D amp's power supply, a lot of good basic info that also applies to hefty Class A amp power supplies. If you are NOT familiar with PSU basics, I recommend you read before "bending tin" and soldering parts......
Building a Gainclone chip amp power supply.
The following link had been posted on the diyaudio "Class D" amp forum about two years ago, and steers you to a good overview of power supply construction. Credit goes to the "Decible Dungeon" for the article.
Although it references construction for a Class D amp's power supply, a lot of good basic info that also applies to hefty Class A amp power supplies. If you are NOT familiar with PSU basics, I recommend you read before "bending tin" and soldering parts......
Building a Gainclone chip amp power supply.
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CanAm Man,
Thank you for your concern. I will follow your advice and try to hook up with a more experienced builder.
And thank you for the very informative link that you send. Good newbie explanation helped me a lot.
And what i will do with regards to C9 is to use a 0.0033uf mains voltage capacitor, and a thermistor to connect the two primary windings if i end up with a transformer having theses.
And again thank you for helping out with advice, and explaining the inrush thing.
Best regards
Mr. Green
P.s.
I think i will put my thought on this board for a check when the time comes
Thank you for your concern. I will follow your advice and try to hook up with a more experienced builder.
And thank you for the very informative link that you send. Good newbie explanation
helped me a lot.And what i will do with regards to C9 is to use a 0.0033uf mains voltage capacitor, and a thermistor to connect the two primary windings if i end up with a transformer having theses.
And again thank you for helping out with advice, and explaining the inrush thing.
Best regards
Mr. Green
P.s.
I think i will put my thought on this board for a check when the time comes
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If I understand your comment, above, are you planning on putting a 25V capacitor across the primary windings of the power transformer--where the capacitor (and an electrolytic, at that....) will be exposed to your full mains voltage??? If I read that right, I really, really want to caution you about the voltages (lethal) that you are coping with. Any low-voltage electrolytic exposed with full mains voltage will (almost certainly) explode, with resulting damage to the PSU, amp, and perhaps the constructor. An F5 PSU can be a dangerous thing--if at all possible, I recommend you have an EXPERIENCED constructor work with you, and to double-check all your work..... or "subcontract it out" to them. The F5 amp club is a relatively small and select bunch--and we do not want to diminish the club population by one body....!!
------------
As for the thermistor in series with the 240V primary side--the CL-60 thermistors are used to limit "in-rush" current into the transformer under initial start-up. For that reason, the CL-60 is placed in series, to serve as a temperature-dependent variable resistor (higher resistance when cold; lower resistance when the warm up). The KEY THING is to have a CL-60 on EACH primary winding:
1. When wired for 240V, you place the TWO primary windings and ONE CL-60 all in series. (In effect, you only have ONE primary winding, and therefore need only ONE CL-60.)
2. When wired for 120, you place EACH primary winding in series with ITS OWN CL-60, and then wire the two pairs of windings/CL-60s in PARALLEL. (In effect, you have TWO primary winding and therefore need TWO CL-60s--one for each primary winding).
Both of the two variants are depicted in the FW schematic for the F5 amp. Very straightforward, actually.
Be careful. These power supplies can kill you.
They can be dangerous, but this thing doesnt make me near as nervous as the tube amps I've built, with B+ over over 600 volts in my 6550/KT88 PP amp!
Russellc
last i knew user cviller http://www.diyaudio.com/forums/members/cviller.html still had some available . and....... he lives in Denmark
cheers Woody
Unfortunately he is out of boards. Does anybody have some laying around that they dont use, or no some who does. Really want some boards
Should we try and get a batch done ?