jacco vermeulen said:
Rework the transformer to 4 x 15Vac secondaries.
Blitz said:Or design a choke-input-Filter, that will bring you down to 23-24 V. But it is easy to buy new transformers I guess.
Thanks for the suggestions.
How do you rework it to 4 x 15V? Is it to rewind it?
I've thought about a variac/choke, and also triac control for the AC but decided to have less parts in line with the Zen philosophy.
Also I'm not sure if using a "capacitor bridge? for a floating ground?" will work (i.e., 2 caps in series tied to 0 and 38V, tap in the middle for 0V...so I can have -19V 0V +19V... sorry I don't know the correct name for this circuit)
My question still is will I blow something up with +-38V rails? Thanks.
dwRK said:
My question still is will I blow something up with +-38V rails? Thanks.
Most likely you will fry the Jfets as these have a breakdown voltage of ~25V. If I know NP only a tiny bit, it is not by chance that the F4 uses a 23V rails.....
Great looking speakers How does they sound?
Thank's Steenoe ... I guess they sound like your''e abbeys, but perhaps, with a little more punch. Well theyr'e not completly finish yet, still missing final coat, edge banding and some wooden phase-plugs
They are very heavy, as i filled the room beneth with drysand (The kind used to blow paint on walls off)
Jesper.
lykkedk said:
Thank's Steenoe ... I guess they sound like your''e abbeys, but perhaps, with a little more punch. Well theyr'e not completly finish yet, still missing final coat, edge banding and some wooden phase-plugs
They are very heavy, as i filled the room beneth with drysand (The kind used to blow paint on walls off)
Jesper.
Looking forward to audition them
....and nice work BTW.
Magura
Zen Mod said:
just pump the gain of Pumpie
15x (23,5db) is completely same as 10x , for Pumpie ......... but not for F4
I might just have to do that ... so, 23.5dB gain... anyway to convince me with numbers that this will make these hard to drive speakers sing loudly? Extra points for using acoustic watts
Tarasque said:Most likely you will fry the Jfets as these have a breakdown voltage of ~25V. If I know NP only a tiny bit, it is not by chance that the F4 uses a 23V rails.....
All First Watt amplifiers have either 23, +/-23, or 46V power
supplies.
This is because NP has tons (literally) of Plitron transformers with
twin 18 VAC secondaries.
luvdunhill said:now that I have all the parts for a F4, I'm wondering if it's the best amp to build ... I'm working a pair of speakers that are shaping up to have the following specs:
about 3dB of BSC
-3dB response at 39 Hz
the woofer is ~86dB efficiency
sum is around 83dB/W/m
I haven't decided really on a proper preamp to drive the F4, so that could definitely be a factor in the equation.
Any opinions?
More efficient speakers or a different amp.
Nelson Pass said:
............
This is because NP has tons (literally) of Plitron transformers with
twin 18 VAC secondaries.
baaaad NP......... baaaaaaaaad!
Posted by Magura:
Ahhh... Don't be so sure about that my freind
luvdunhill : Whitout being bad i would like to tell, that with the experiance i have had with my 87dB speaker's with balanced F4's, it might be, that you will be dissapointed, if you wish to play loud. Just my oppinion, nothing else! - And i am not a guru, that's for sure!!!
Jesper.
With a balanced F4, yes it will make just about anything sing at 23dB gain
Ahhh... Don't be so sure about that my freind
luvdunhill : Whitout being bad i would like to tell, that with the experiance i have had with my 87dB speaker's with balanced F4's, it might be, that you will be dissapointed, if you wish to play loud. Just my oppinion, nothing else! - And i am not a guru, that's for sure!!!
Jesper.
Re: Please help with PSU questions
I;m sure that the scaling up of R5 and R22 does work.
dwRK said:1. Can I run F4 rails at +/- 36~38V? What do I need to scale up (based on rev R0, I'm thinking R5, R22, and maybe the source resistors for better? stability?).
I;m sure that the scaling up of R5 and R22 does work.
lykkedk said:Posted by Magura:
Ahhh... Don't be so sure about that my freind
luvdunhill : Whitout being bad i would like to tell, that with the experiance i have had with my 87dB speaker's with balanced F4's, it might be, that you will be dissapointed, if you wish to play loud. Just my oppinion, nothing else! - And i am not a guru, that's for sure!!!
Jesper.
Jesper:
any chance you could try upping the Pumpkin gain and giving it another go?
Jesper:
any chance you could try upping the Pumpkin gain and giving it another go?
I tried a gainsetting at allmost 28x (150k / ~5,5k) Donno how many dB it give's...
I wasen't capable of making this work proberly, maybee it's my pcb-layout or something else, but the max gainsetting is around ~20 for my setup (homemade pcb), for prober noise/hum floor...
I must say, (Before ZenMod ) that this was not with my LeachAmp
I tried begging the Master ZenMod for buying 1 of his kit's, but he's just like me ... the answer was, ''not until you fix problem " I kind of knew that answer, even before i tried ordering a kit...
Well i belive, that you must have around 27-30x gain with thoose speaker for driving them proberly., with a 1,5vac source.
But But But remember ... i am not a guru ... Maybee it's possible with ZenMod's pumpkin pcb... i donno... ??
Jesper.
lykkedk said:But But But remember ... i am not a guru ... Maybee it's possible with ZenMod's pumpkin pcb... i donno... ??
[/B]
I think it's that special BBQ treatment he applies to each one that is the key. Have you tried that?
b-square said:
More efficient speakers or a different amp.
assuming the former isn't an option, any opinions on the latter?
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