Beginner progress report: Building my F5 Turbo Monoblocks 50WPC
Hi forum members;
After long thinking and searching and reading through forum posts about F5, I decided to build 50 watts of F5 Turbo. My speakers are: KEF LS50
I am now using two bang olufsen 125asx2 as dual mono to feed my speakers and happy with them, but I found that class d amps lacks airyness between instruments and trebles seems a little bit rolled off.
So I decided to pull the trigger and start a project to make my own class a amplifier based on F5 Turbo.
I wanted to build v3 at first (to accomplish 100 watts per channel) but cap, toroidal trafo and heatsink requirements (size and cost) are beyond my expectations.
SO I just want to build a simple 50 watts class a f5 turbo with you dear forum members. I am planning to make small mono block amp for each speaker because I dont have enough space for huge chassis.
My previous DIY experience:
- Aikido 12Vac linestage
- Bang olufsen 50asx2 amplifier
- bang olufsen balanced dual mono 125asx2 BTL
- Master clock, opamp and opamp cap upgrade of my ASUS stx sound card
Should I start the F5 project?
Hi forum members;
After long thinking and searching and reading through forum posts about F5, I decided to build 50 watts of F5 Turbo. My speakers are: KEF LS50
I am now using two bang olufsen 125asx2 as dual mono to feed my speakers and happy with them, but I found that class d amps lacks airyness between instruments and trebles seems a little bit rolled off.
So I decided to pull the trigger and start a project to make my own class a amplifier based on F5 Turbo.
I wanted to build v3 at first (to accomplish 100 watts per channel) but cap, toroidal trafo and heatsink requirements (size and cost) are beyond my expectations.
SO I just want to build a simple 50 watts class a f5 turbo with you dear forum members. I am planning to make small mono block amp for each speaker because I dont have enough space for huge chassis.
My previous DIY experience:
- Aikido 12Vac linestage
- Bang olufsen 50asx2 amplifier
- bang olufsen balanced dual mono 125asx2 BTL
- Master clock, opamp and opamp cap upgrade of my ASUS stx sound card
Should I start the F5 project?
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i have had good luck building F5 v3 monoblocks. Even the 50w F5 will require a fairly large heatsink area. If you build it as monoblocks you still need to have the same heatsink area but in 2 chassis. You need to decide if that requirement will make the amps too big for your space.
I previously owned a W4S sti500 which was 250w/ch class D. It sounded good but I agree with your assessment about the BandO modules lacking somewhat in soundstage size and naturalness of note decay.
I just finished a 4 box monoblock version of the F5V3 and posted a few pictures in the F5turbo builders thread. So far it is sounding very good but it is early days and I haven't finished the power supply chassis yet. Monoblocks mean more expense and work than doing a single stereo amplifier. That may also be something to consider.
I previously owned a W4S sti500 which was 250w/ch class D. It sounded good but I agree with your assessment about the BandO modules lacking somewhat in soundstage size and naturalness of note decay.
I just finished a 4 box monoblock version of the F5V3 and posted a few pictures in the F5turbo builders thread. So far it is sounding very good but it is early days and I haven't finished the power supply chassis yet. Monoblocks mean more expense and work than doing a single stereo amplifier. That may also be something to consider.
Hi Bfpca
Thank you for the reply, actually when you think mono F5T v2 it will require one side of the stereo chasis heatsink. I want to make two small cubic chasis. Actually it would be better to make stereo f5 but this time I can not put the chassis in the center, my system is in living room and two cubic mono blocks will be nearside of the each bookshelf stand.
I am planning to use 4 cpu heatsink in each monoblock and 140mm chassis fan underside of the chassis.
and a question for F5T v2 monolblock should I buy 2 x universal PSU, or can I break and split the PCB into two seperate PCB. (It looks like pcb board can be broke from the center) ??
Thank you for the reply, actually when you think mono F5T v2 it will require one side of the stereo chasis heatsink. I want to make two small cubic chasis. Actually it would be better to make stereo f5 but this time I can not put the chassis in the center, my system is in living room and two cubic mono blocks will be nearside of the each bookshelf stand.
I am planning to use 4 cpu heatsink in each monoblock and 140mm chassis fan underside of the chassis.
and a question for F5T v2 monolblock should I buy 2 x universal PSU, or can I break and split the PCB into two seperate PCB. (It looks like pcb board can be broke from the center) ??
Thank you AndrewT for suggestion.
As I understand from the schematic of the Uni PSU board, I should buy one PCB for each monoblock build. That means I will order 2 x PSU from store.
Also I want to ask, should I buy softstart circuit and speaker protection?
I think F5T v2 will not suck huge electricity?
As I understand from the schematic of the Uni PSU board, I should buy one PCB for each monoblock build. That means I will order 2 x PSU from store.
Also I want to ask, should I buy softstart circuit and speaker protection?
I think F5T v2 will not suck huge electricity?
I would look at a lot more than just DC detection and isolation for a DC coupled amplifier.
AC coupling both at the input and in the NFB is much safer. Without that extra safety you need to replace those two capacitors with a lot of hardware.
And yes, mains fusing becomes much easier if you put in a soft start (current limiter) on each primary winding.
A rectifier and smoothing cap bank does not need a PSU PCB. Hard wiring it is cheap and easy and usually more compact.
AC coupling both at the input and in the NFB is much safer. Without that extra safety you need to replace those two capacitors with a lot of hardware.
And yes, mains fusing becomes much easier if you put in a soft start (current limiter) on each primary winding.
A rectifier and smoothing cap bank does not need a PSU PCB. Hard wiring it is cheap and easy and usually more compact.
Is that a question, or a statement?
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Of course not, just asking. Actually because of my monoblock plan, each block will have their own toroid and own psu, thats why I think electricity inrush will not be very high. Am I right? So I am after for cheaper option than soft start kit.
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a 50W classA amplifier needs a transformer rated somewhere between 6times and 10times it maximum output power.
That puts your transformer requirement for this 50W proposal around 300VA to 500VA.
the idling (quiescent) current could be around 1.9A and the supply rails around 35Vdc, add on a bit for the drivers and input stage and the total power consumption will be around 150W per channel. Add on another bit for transformer efficiency and your two channels may be drawing 320W continuously.
That comes to ~£280/year for 16hours/day @ 15p/kWh
Does that answer your question?
If your house needs that 320W of heating during winter, spring and autumn, then consider the 320W & £280 as your home heating cost and your music comes free for 9months of the year.
That puts your transformer requirement for this 50W proposal around 300VA to 500VA.
the idling (quiescent) current could be around 1.9A and the supply rails around 35Vdc, add on a bit for the drivers and input stage and the total power consumption will be around 150W per channel. Add on another bit for transformer efficiency and your two channels may be drawing 320W continuously.
That comes to ~£280/year for 16hours/day @ 15p/kWh
Does that answer your question?
If your house needs that 320W of heating during winter, spring and autumn, then consider the 320W & £280 as your home heating cost and your music comes free for 9months of the year.
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inrush current protector board and spekaer protection boards in the diyaudio store are for stereo setup, I will need 2 boards for monoblocks, so may I use completed boards from ebay (cheaper option).
For the speaker protection, do relays on the protection boards effects output quality?
should I consider not using any speaker protection?
For the speaker protection, do relays on the protection boards effects output quality?
should I consider not using any speaker protection?
recepky:
I built F5 Turbo V3 monblocks a few years ago and am very happy with the results, but I also have the good fortune of living near another diyAudio member who has built and/or has access to other Firstwatt amplifiers. In your second post, you noted that space considerations necessitated your building two small monoblocks instead of a centrally-located stereo amp. I suspect you could build 50 watt F5 Turbo V3 monoblocks in a pair of the store's Deluxe 4U chassis, but I would also urge you to consider building a lower-powered monoblock version of the F6 instead. The difference between 25 watts and 50 watts is far less than you might imagine and the F6 strikes me as a design that is more consistent with Nelson Pass' "house sound" than the F5 Turbo. Either way you will be happy, but you might be able to find a chassis smaller than the Deluxe 4U to house one channel of an F6.
Just a thought...
Regards,
Scott
I built F5 Turbo V3 monblocks a few years ago and am very happy with the results, but I also have the good fortune of living near another diyAudio member who has built and/or has access to other Firstwatt amplifiers. In your second post, you noted that space considerations necessitated your building two small monoblocks instead of a centrally-located stereo amp. I suspect you could build 50 watt F5 Turbo V3 monoblocks in a pair of the store's Deluxe 4U chassis, but I would also urge you to consider building a lower-powered monoblock version of the F6 instead. The difference between 25 watts and 50 watts is far less than you might imagine and the F6 strikes me as a design that is more consistent with Nelson Pass' "house sound" than the F5 Turbo. Either way you will be happy, but you might be able to find a chassis smaller than the Deluxe 4U to house one channel of an F6.
Just a thought...
Regards,
Scott
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Hi SRMcGee;
thank yu very much for the suggestion, I already ordered the F5 Turbo pcb s from the store but I think extra 25 watts will be good for the inefficient kef ls50 (85 dB) For the chassis and heatsinks I am planing to solve these problems locally. I am planning to use 220x260x330mm chasis with heatsinks inside (!) and with a one big 140mm low rpm fan on the back.
by the way very very nice amplifiers! are they 100 watts per mono block?
thank yu very much for the suggestion, I already ordered the F5 Turbo pcb s from the store
but I think extra 25 watts will be good for the inefficient kef ls50 (85 dB) For the chassis and heatsinks I am planing to solve these problems locally. I am planning to use 220x260x330mm chasis with heatsinks inside (!) and with a one big 140mm low rpm fan on the back.by the way very very nice amplifiers! are they 100 watts per mono block?
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recepky:
Thanks! My F5T's are currently biased for about 110 watts per channel into 8 ohms. I'm pretty confident that I could bump them up to around 200 watts per channel, but I don't need the power or the heat (or the energy consumption).
Good luck with your project. Please post photos!
Regards,
Scott
Thanks! My F5T's are currently biased for about 110 watts per channel into 8 ohms. I'm pretty confident that I could bump them up to around 200 watts per channel, but I don't need the power or the heat (or the energy consumption).
Good luck with your project. Please post photos!
Regards,
Scott
thanks for the reply SRMcGee
I want to show you my chassis design.
Here you can see the plan
you can recognize the toroid and psu pcb and caps. the box in the upper corner is front end pcb
From this perspective you can see the N channel and P channel boards, the big foots are the cooling heatsinks that have more than enough surface area (8xCPU heatsink)
One side of the box is left for the electricity input, rca input, speaker output and 140 mm exhaust fan.
This is the chasis that I want to use for each mono block.
What do you think? Am I missing something?
I want to show you my chassis design.
Here you can see the plan
you can recognize the toroid and psu pcb and caps. the box in the upper corner is front end pcb
From this perspective you can see the N channel and P channel boards, the big foots are the cooling heatsinks that have more than enough surface area (8xCPU heatsink)
One side of the box is left for the electricity input, rca input, speaker output and 140 mm exhaust fan.
This is the chasis that I want to use for each mono block.
What do you think? Am I missing something?
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i build a vertical arranged f5t, take a look here http://www.diyaudio.com/forums/pass...-your-diy-pass-amplifier-280.html#post4050787 , i can get up to 2 x 44 watt max. i don't think that will work with this case, even with a fan you will look for a vertikal uninterrupted airflow.
my case has a lot o ventig holes and airflow channels to suck the hot air out. the concept i had needed some afterwork to run fine. i learned a lot with this amp, vertikal heatsink this high are 2/3 as efficent as horzizontal arranged. the two most important things are heat sink size and free flow of the air, i think you will run into troube with trapped heatspots in this case even with a monster fan.
my case has a lot o ventig holes and airflow channels to suck the hot air out. the concept i had needed some afterwork to run fine. i learned a lot with this amp, vertikal heatsink this high are 2/3 as efficent as horzizontal arranged. the two most important things are heat sink size and free flow of the air, i think you will run into troube with trapped heatspots in this case even with a monster fan.
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the cold air intake comes from bottom of the chassis and leaves hot air from the back of the chassis in the design. actually I rely on 8 x AMD cpu heatsinks, because you now cpu's get as hihg as 70degrees in normal operation and with heatsink it stays with that heat. I am planing to use one or more fans over heatsinks if I get in trouble, anyway like your example if I get in more trouble that means I will drill holes on the chasis side panels in the CNC
by the way I saw your pictures, what a cute design!, but it seems your chasis is smaller compared to xigmatek chasiss that I will use.
by the way I saw your pictures, what a cute design!, but it seems your chasis is smaller compared to xigmatek chasiss that I will use.
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actually it looks like smaller than yours
but you designed the chasis for stereo right? mine will be mono, two box system
yes for stereo. but the pcbs are with 2*6 mosfet smaler then the standard f5t with 2*8 mosfets. i planed to get easy 2 x 50 watt but it runs to hot, i maxed out the chassis to get 2 x 44 watt, and this amp weight over 30kg/66 lbs most weight alluminium for cooling/heat transfer.
if i build this amp for a friend i would lower the bias a bit (38-40watt), the heatsink can get up to 60c on a hot summer day, safe if you keep a eye on it but a better target is 55c. what's not so nice with a hot case is that the caps aging a lot faster, the rest is fine.
if i build this amp for a friend i would lower the bias a bit (38-40watt), the heatsink can get up to 60c on a hot summer day, safe if you keep a eye on it but a better target is 55c. what's not so nice with a hot case is that the caps aging a lot faster, the rest is fine.
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