This is my first thread so be indulgent !
I fall in the audiophile world some years ago, beginning with buying some nice little market amp (NAD310 / NAD325 / Advance MAP-101).
So, as i'm a diy guy since my childhood, i'd like to mount one class A. I found some design like "Le monstre", JLH1969, ZEN, SoZ, Aleph, DOZ and others.
I finally decided to mount one DoZ. So i'm opening this thread to grab some advice from the "cadors" as you are !
Oh ! I forgot : i'm french and my english is rather crude ...
My goals are (who said challenge ?) :
- tiny box (220x170x55), from an old active crossover i make 20 years ago ...
- fan ventilated, 2x40mm 12V low-noise fan (12.3dB), with managed air flow (18.6m3/h).
- single-ended 35V (one 200VA/2x24v transformer output per channel)
- 15w RMS on 8 ohm speakers (Heybrook HB3 Series 2 and maybe others with higher efficiency later)
I realize it's not in mentality of most of your feat, but i like do thinks not like everyone ;o)
I draw a schematic of the box with transformer, capacitors (4x22mF), heatsinks, ... very narrow but OK. I have the place for 2 main mono boards (50x100mm).
All fit theorically in the box. The air flow is totally ducted through the heatsink (18.6m3/h).
I think i can use the original Westhost PCB, so not really anxious that it will not work.
My doubts are for :
- the transformer power (is 200VA OK?)
- capacitors : is 2x22mF per channel too fat ? May be 2x10mF is sufficient ? And if my main power is at 34V, could i use 35V capacitors (for gain of place) ?
- what output capacitors to use ?
- transistors : MJL4281 / MJL21194. Which one do you recommend ?
- HP protection : is it necessary as i have seen many people use this kind of protection ? Are the speakers protected from burning transistors without ?
- can i use the main power of the amp to supply the fan (0.6w) with filtering. Maybe around the D2 12v zener ?
I'm interesting on any advice from any of you.
Thanks to spend some time for me !
Mick
PS : I presented this project in an other thread but there was no response to my precise questions. So i create this new dedicated thread.
PS2 : for those who would like to mention all my english faulty, i'll be happy to receive them by MP 😉 If this thread could help me to improved my english too, it would be nice !
I fall in the audiophile world some years ago, beginning with buying some nice little market amp (NAD310 / NAD325 / Advance MAP-101).
So, as i'm a diy guy since my childhood, i'd like to mount one class A. I found some design like "Le monstre", JLH1969, ZEN, SoZ, Aleph, DOZ and others.
I finally decided to mount one DoZ. So i'm opening this thread to grab some advice from the "cadors" as you are !
Oh ! I forgot : i'm french and my english is rather crude ...
My goals are (who said challenge ?) :
- tiny box (220x170x55), from an old active crossover i make 20 years ago ...
- fan ventilated, 2x40mm 12V low-noise fan (12.3dB), with managed air flow (18.6m3/h).
- single-ended 35V (one 200VA/2x24v transformer output per channel)
- 15w RMS on 8 ohm speakers (Heybrook HB3 Series 2 and maybe others with higher efficiency later)
I realize it's not in mentality of most of your feat, but i like do thinks not like everyone ;o)
I draw a schematic of the box with transformer, capacitors (4x22mF), heatsinks, ... very narrow but OK. I have the place for 2 main mono boards (50x100mm).
All fit theorically in the box. The air flow is totally ducted through the heatsink (18.6m3/h).
I think i can use the original Westhost PCB, so not really anxious that it will not work.
My doubts are for :
- the transformer power (is 200VA OK?)
- capacitors : is 2x22mF per channel too fat ? May be 2x10mF is sufficient ? And if my main power is at 34V, could i use 35V capacitors (for gain of place) ?
- what output capacitors to use ?
- transistors : MJL4281 / MJL21194. Which one do you recommend ?
- HP protection : is it necessary as i have seen many people use this kind of protection ? Are the speakers protected from burning transistors without ?
- can i use the main power of the amp to supply the fan (0.6w) with filtering. Maybe around the D2 12v zener ?
I'm interesting on any advice from any of you.
Thanks to spend some time for me !
Mick
PS : I presented this project in an other thread but there was no response to my precise questions. So i create this new dedicated thread.
PS2 : for those who would like to mention all my english faulty, i'll be happy to receive them by MP 😉 If this thread could help me to improved my english too, it would be nice !
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Hi, it's not nice when someone gets ignored !
What's a DOZ ? I realise it must be a Class A amp, but i've never heard of it. Be better if you provided a link, or two 😉
Transformer @ 200VA = Fine
2x22mF per channel = Fine if they fit, if not whatever will.
35V capacitors = NO, they should be 50V for safety.
Get the highest uf capacitors @ 50V you can, with the lowest ESR & cost.
Re - transistors, we havn't seen the circuit yet ?
RE - HP protection. Do you mean High Pass as in low frequency filter, or DC protection, or both ? The speakers won't be protected from blown transistors etc, without a good DC protection circuit.
Yes you could supply the fan simply via a resistor in series with it.
By the way, i'm not a Class A builder, i just thought you deserved a response 😉 Hope you get some more !
What's a DOZ ? I realise it must be a Class A amp, but i've never heard of it. Be better if you provided a link, or two 😉
Transformer @ 200VA = Fine
2x22mF per channel = Fine if they fit, if not whatever will.
35V capacitors = NO, they should be 50V for safety.
Get the highest uf capacitors @ 50V you can, with the lowest ESR & cost.
Re - transistors, we havn't seen the circuit yet ?
RE - HP protection. Do you mean High Pass as in low frequency filter, or DC protection, or both ? The speakers won't be protected from blown transistors etc, without a good DC protection circuit.
Yes you could supply the fan simply via a resistor in series with it.
By the way, i'm not a Class A builder, i just thought you deserved a response 😉 Hope you get some more !
Thanks a lot Zero D.
The Doz I effectively a class A amp. The main link is Death of Zen - A new Class-A power amp
It's OK for the transformer and power supply capacitors.
I talked about DC protection. So i think to use the westhost one Loudspeaker Protection and Muting
For the fans, i thought of using one of the D2 zener which is used to regulate the amp power supply (see the amp circuit).
I don't know how to use and choose the output decoupling capacitors. So if you have an idea ...
Thanks again.
The Doz I effectively a class A amp. The main link is Death of Zen - A new Class-A power amp
It's OK for the transformer and power supply capacitors.
I talked about DC protection. So i think to use the westhost one Loudspeaker Protection and Muting
For the fans, i thought of using one of the D2 zener which is used to regulate the amp power supply (see the amp circuit).
I don't know how to use and choose the output decoupling capacitors. So if you have an idea ...
Thanks again.
DOZ = Death Of Zen, Ahhh now i see 😉
Re - transistors. As high hfe & current as possible, i would say.
The Westhost Loudspeaker Protection and Muting should be fine.
Re - Output decoupling capacitor. 4700uf @ 35V should be fine
Re - Fan. I wouldn't run it off there. Instead use a series resistor from the + DC to the fan + For eg, if the fan is a 12V 100mA type, use a 220 Ohm 5W resistor, preferably bolted to the chassis or heatsink. This type WH5 220R JI - WELWYN - RESISTOR, 10W 5% 220R | Farnell United Kingdom
Re - transistors. As high hfe & current as possible, i would say.
The Westhost Loudspeaker Protection and Muting should be fine.
Re - Output decoupling capacitor. 4700uf @ 35V should be fine
Re - Fan. I wouldn't run it off there. Instead use a series resistor from the + DC to the fan + For eg, if the fan is a 12V 100mA type, use a 220 Ohm 5W resistor, preferably bolted to the chassis or heatsink. This type WH5 220R JI - WELWYN - RESISTOR, 10W 5% 220R | Farnell United Kingdom
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Well im running my cpu fan with 0,5W 100R resistor, its warm but never hot, my pc is silent also psu fan has resistor (cant remember the R) but it barely starts up, going super slow, even at mid summer 30°C outside my cpu max temp is 40 degrees, before i i had dat smart fan sh... going on and it was fully retarded-
Do you have DOZ working? If so, I hope you are enjoying the music.
So, you have a 0.5W resistor instead of 5W to supply the fan. I guess it is a very small fan motor. Are you supplying it with 35V as recommended or from the D2 zener? What is the voltage supply to the fan (measured across the fan terminals) when operating?
So, you have a 0.5W resistor instead of 5W to supply the fan. I guess it is a very small fan motor. Are you supplying it with 35V as recommended or from the D2 zener? What is the voltage supply to the fan (measured across the fan terminals) when operating?
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