Hi guys,
i see a lots of guys are interested in pcb of bpa 300, and rates some of them have got are very high in comparison to what i get here.
i just enquired a pcb manufacturer for bpa300 pcb for me, and the quote i got is 2.5$ per pcb for a lot of minimum 25 pcbs, so if you guys need any help i could get it done as i am already ordering some for me.
i see a lots of guys are interested in pcb of bpa 300, and rates some of them have got are very high in comparison to what i get here.
i just enquired a pcb manufacturer for bpa300 pcb for me, and the quote i got is 2.5$ per pcb for a lot of minimum 25 pcbs, so if you guys need any help i could get it done as i am already ordering some for me.
hey alex sweet amps, i've been admiring them for years, and recently i ordered some pa-150 boards off ebay and made myself a 150w per channel amp. I am not very knowledgeable about analog and gain structure and such. The pcbs i ordered (from Hong Kong) appear to be essentially the same as yours (same resistors and such). How do i calculate the gain, and would a preamp with a gain of 20db be overkill for my amp? thanks in advance
300W into 8ohm requires an output signal of 49Vac.
The minimum gain of a standard 3886 chipamp implementation is +20dB (=10times). Better performance is usually obtained by increasing the power amp gain to between +26dB and +30dB.
This makes the maximum signal into the amplifier ~4.9Vac, for +20dB amp gain.
Or <=2.45Vac for +26dB amp gain.
If you build a pa150, the gains and sensitivities are the same.
However, a BPA300 has double the gain of a PA150.
The minimum gain will be +26dB and the preferred performance gain will be between +32dB and +36dB. This will require a maximum input of between 2.45Vac (+26dB amp gain) down to 613mVac (+36dB amp gain).
If a signal from a source is a maximum of 200mVac and you need between 613mVac and 2450mVac then the range of preamp gain required is +10dB to +22dB.
If your maximum signal is 400mVac you need 6dB less preamp gain.
If signal is 800mVac then 12dB less preamp gain.
If 1600mVac then 18dB less preamp gain.
If 2200mVac (about CD Player level) you need 21dB less preamp gain.
i.e. a CDP will not require any gain in the pre-amp to drive the BPA300 to maximum power.
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Wow thanks for the great info! I'm a little confused on what you mean by "less preamp gain". I have reason to believe my pa-150 is configured with a gain of 20db. If I am using my iPod and sony playstation as inputs (both actually have an output voltage of about 1000mvac, what total gain / final input voltage would i need to achieve max power from my pa-150? Would a preamp with gain of 20db be acceptable?
Have you tried these threads?
http://www.diyaudio.com/forums/grou...150-bpa300-project-together-drv134-pcb-3.html
http://www.diyaudio.com/forums/group-buys/137430-bpa300-round-2-a-37.html
You might have some luck with the members who bought but then didn't implement their boards.
http://www.diyaudio.com/forums/grou...150-bpa300-project-together-drv134-pcb-3.html
http://www.diyaudio.com/forums/group-buys/137430-bpa300-round-2-a-37.html
You might have some luck with the members who bought but then didn't implement their boards.
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From alexw88 First group buy, this boards maybe first prototype
honestly i want keep this board but if i think once again this is not ok
cause alex the creator give him afford to us to get this beautiful amp
I hear another lm 3886 board, from local store, hand made, local gb
even from china. Looks like this material of copper rail was very good
if no one interested i will sell it in swap meat or ebay letter
honestly i want keep this board but if i think once again this is not ok
cause alex the creator give him afford to us to get this beautiful amp
I hear another lm 3886 board, from local store, hand made, local gb
even from china. Looks like this material of copper rail was very good
if no one interested i will sell it in swap meat or ebay letter
Attachments
How to make this amplifier sound excellent
1. transformer
when we make a blind test use different tansformer EI & Toroids
Toroids make a good bass in here, dont forget to check secondary output
are they output are the same
I used Nuvotem Talema 25-0 25-0 same as alexw88,
if you got plitron it must be the best for supply
2. PSU
With Elna for Audio this amp sound excellent and pls used bridge rectrifier
mda 3504 even they very expensive but the sound is death quit
3. Earth - Grounding
use 10 ohm 5w resistor from earth to amp chassis, non inductivefor supply .
i used wirewound, maybe mills or ricken will be ok too here
4. Cable
use cable for supply in 14 awg, connect your cable first with magnet
if they connect together pls do not use your cable. Try to find copper
cable not use silver over copper (maybe silver over copper over whatever)
one thing always happen pls be careful to connect suplly + to +, G to G, and
- to -. This is a very simple amp and design if you working carefully so it will
shine your world after
for input cable you can get the teflon cable usually they got +/-/g
for output cable try to find speaker cable there will be a lot of effect
5. Channel Capacitor 2200uf 50v
i try some of caps there
- panasonic fc the sound will be mellow,
- cerafine the sound go to natural but little bit thinner
- silmic add the effect of the bass will be good if you build sub
- nichicon kg the sound go natural
- nichicon fx the sound more natural
- bg std the sound is so good
6. Capacitor 100uf 50v
i try some of caps there
- panasonic fc the sound mellow,
- cerafine the sound little bit thinner
- silmic was effect here very good result
- BGN, maybe my ear was wrong not good in here
- BG Std not good in here too
7. All component inside (SMD)
try to get avx component, for 0.2ohm 1 watt the original was vishay dale
if you dont get it try to get mills there
8. 10uf Film Capacitor
If you use film caps you can choose
- Mundorf family caps (white, supreme, silver in oil)
- good version too is k73-16
if you choose to use ot like jentsen or lundalh you dont need
too use capacitor here
9. Bias
Make a good bias, until you got all lm 3886 at the same bias
10. cable terminal
unsolder all cable terminal for supply, input & output
use a direct solder in there
11. solder
if you got better budget try to use wbt or mundorf ag/au
or wonder caps 5 m solder more than enough to solder
all connection in there
Thank you, best regards
1. transformer
when we make a blind test use different tansformer EI & Toroids
Toroids make a good bass in here, dont forget to check secondary output
are they output are the same
I used Nuvotem Talema 25-0 25-0 same as alexw88,
if you got plitron it must be the best for supply
2. PSU
With Elna for Audio this amp sound excellent and pls used bridge rectrifier
mda 3504 even they very expensive but the sound is death quit
3. Earth - Grounding
use 10 ohm 5w resistor from earth to amp chassis, non inductivefor supply .
i used wirewound, maybe mills or ricken will be ok too here
4. Cable
use cable for supply in 14 awg, connect your cable first with magnet
if they connect together pls do not use your cable. Try to find copper
cable not use silver over copper (maybe silver over copper over whatever)
one thing always happen pls be careful to connect suplly + to +, G to G, and
- to -. This is a very simple amp and design if you working carefully so it will
shine your world after
for input cable you can get the teflon cable usually they got +/-/g
for output cable try to find speaker cable there will be a lot of effect
5. Channel Capacitor 2200uf 50v
i try some of caps there
- panasonic fc the sound will be mellow,
- cerafine the sound go to natural but little bit thinner
- silmic add the effect of the bass will be good if you build sub
- nichicon kg the sound go natural
- nichicon fx the sound more natural
- bg std the sound is so good
6. Capacitor 100uf 50v
i try some of caps there
- panasonic fc the sound mellow,
- cerafine the sound little bit thinner
- silmic was effect here very good result
- BGN, maybe my ear was wrong not good in here
- BG Std not good in here too
7. All component inside (SMD)
try to get avx component, for 0.2ohm 1 watt the original was vishay dale
if you dont get it try to get mills there
8. 10uf Film Capacitor
If you use film caps you can choose
- Mundorf family caps (white, supreme, silver in oil)
- good version too is k73-16
if you choose to use ot like jentsen or lundalh you dont need
too use capacitor here
9. Bias
Make a good bias, until you got all lm 3886 at the same bias
10. cable terminal
unsolder all cable terminal for supply, input & output
use a direct solder in there
11. solder
if you got better budget try to use wbt or mundorf ag/au
or wonder caps 5 m solder more than enough to solder
all connection in there
Thank you, best regards
I cannot understand what you are describing.
I can interpret it using my existing knowledge and come up with a layout that is safe.
Unfortunately I can use your description to create a layout that is potentially lethal
Please clarify exactly what you are recommending or delete this para completely.
I am trying but not really being able to understand you. Are these boards from the first alexw88 group buy?
Hi
yes they are came from 1st gb bpa300 by alexw88
from boards we received 4 is black colour the others is blue
yes they are came from 1st gb bpa300 by alexw88
from boards we received 4 is black colour the others is blue
Attachments
Hi all,
please do excuse my noobness.
I have a few questions about the PA150 board.
First of all, will the components specified by alex on his website be the same if I want to run the bords in un-bridged mode, stereo 2x150W ?
Pocoyo, a few posts above me mentions a resistor, 10 ohm 5w from earth to amp chassis, wich is deemed leathal. My question is, how is this diffrent than the choke + resistor alex used in his design, shouldn't his design also be leathal?
The input cap alex uses is rated at 400V, is it safe to use something lower like 250V? And how low can I go on the uf rating? Will there be any negative effect if I go below 10uf?
Ive seen these boards circulating on ebay with lower quality components that surely will effect the sound quality but im intrested mainly in their choice of ballast resistors. They use rectangle ceramic/cement resistors instead of the type recomended by alex. How do they compare to those used by alex in his design?
Again, Im a total amature and beginner at this.
Regards,
Mackis
Sweden
please do excuse my noobness.
I have a few questions about the PA150 board.
First of all, will the components specified by alex on his website be the same if I want to run the bords in un-bridged mode, stereo 2x150W ?
Pocoyo, a few posts above me mentions a resistor, 10 ohm 5w from earth to amp chassis, wich is deemed leathal. My question is, how is this diffrent than the choke + resistor alex used in his design, shouldn't his design also be leathal?
The input cap alex uses is rated at 400V, is it safe to use something lower like 250V? And how low can I go on the uf rating? Will there be any negative effect if I go below 10uf?
Ive seen these boards circulating on ebay with lower quality components that surely will effect the sound quality but im intrested mainly in their choice of ballast resistors. They use rectangle ceramic/cement resistors instead of the type recomended by alex. How do they compare to those used by alex in his design?
Again, Im a total amature and beginner at this.
Regards,
Mackis
Sweden
Because in Alex's design, the AC ground/safety earth is connected directly to the chassis and the choke+resistor are between the amp ground and the safety earth.
Putting a resistor between the safety earth and the chassis can act like a fuse, blowing the resistor and leaving the chassis live and potentially deadly if a fault occurs.
