Where did you get those four Apex PA04 chips and how much were they? They are legendary (as in unaffordable), list for $450 each at Mouser, about $180 each on ebay!
Yes, I know they are pricey, as were the PA07 and PA12 I used in previous builds.
I bought used PA04 from American eBay sellers.
I suspect the ones on eBay from China are fake.
I bought used PA04 from American eBay sellers.
I suspect the ones on eBay from China are fake.
bench amp, 2 x 3886 (my own layout and PCB) - Speaker delay and protect.
NAD C320BEE Upgrade-Fix with Neurochrome 3886DR
What to do with an old (vintage) amplifier that has intermittent problems. Mine worked in daily use for years. I repaired it twice because of shorted or dry caps but then it started having random volume fluctuations. Random problems are difficult to fix because one can't be sure that the latest remedy is the fix. I decided to recycle but I had second thoughts because the enclosure was in perfect condition, I just needed to replace the mainboard.
So 3886DR to the rescue. They were easy to attach to the main heatsink where there are totally chimney-cooled fins. There is plenty of room for DIY pcbs which support the bass-treble-balance-volume pots. The pots were difficult to find on Mouser. I got four 10k with 20mm flat-D shafts.
I attach photos of the old mainboard and the 3886DR upgrade.
What to do with an old (vintage) amplifier that has intermittent problems. Mine worked in daily use for years. I repaired it twice because of shorted or dry caps but then it started having random volume fluctuations. Random problems are difficult to fix because one can't be sure that the latest remedy is the fix. I decided to recycle but I had second thoughts because the enclosure was in perfect condition, I just needed to replace the mainboard.
So 3886DR to the rescue. They were easy to attach to the main heatsink where there are totally chimney-cooled fins. There is plenty of room for DIY pcbs which support the bass-treble-balance-volume pots. The pots were difficult to find on Mouser. I got four 10k with 20mm flat-D shafts.
I attach photos of the old mainboard and the 3886DR upgrade.
Attachments
4x LM3886 for my active speakers. Still got a second one to make..
Reply to post #3511
In Walt Disney Hall the sound pressure of a classical concert can at the loudest moments reach 95dB and if you are sitting behind the orchestra it might get to 98dB. (look at the attached pictures) As the spectral characteristic of the classical music is very different from that of rock or electronic music, the levels there might be much higher.
In a reasonably sized leaving room of 450sq.f. and speakers' sensitivity of 86dB you need much more than 5W to get to these levels. And of course you need at least 25% reserve.
The subjective perception of the loudness is directly connected with the quality of the amplifier/speakers. When your amp is not very good quality i.e. high THD (tube amps for example) the loud music is often perceived as annoying and unpleasant. But the same music at the same sound levels played by high quality amp i.e. very low THD, sounds nice and pleasant. This is a well known fact.
In Walt Disney Hall the sound pressure of a classical concert can at the loudest moments reach 95dB and if you are sitting behind the orchestra it might get to 98dB. (look at the attached pictures) As the spectral characteristic of the classical music is very different from that of rock or electronic music, the levels there might be much higher.
In a reasonably sized leaving room of 450sq.f. and speakers' sensitivity of 86dB you need much more than 5W to get to these levels. And of course you need at least 25% reserve.
The subjective perception of the loudness is directly connected with the quality of the amplifier/speakers. When your amp is not very good quality i.e. high THD (tube amps for example) the loud music is often perceived as annoying and unpleasant. But the same music at the same sound levels played by high quality amp i.e. very low THD, sounds nice and pleasant. This is a well known fact.
Attachments
In 2011 reboot of my DIYaudio hobby started with a chipamp...
single sided. The 0.9 Version of the housekeeping circuit is good viewable...
Homebrew single sided pcb. Circuit from LME49830 datasheet. IRFP240/9240 based. About 150W/8R. Still many LME49830 on stock. A great chipamp chip!
Have fun, Toni
single sided. The 0.9 Version of the housekeeping circuit is good viewable...
Homebrew single sided pcb. Circuit from LME49830 datasheet. IRFP240/9240 based. About 150W/8R. Still many LME49830 on stock. A great chipamp chip!
Have fun, Toni
Attachments
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An old small project for a friend some years ago. 2 mono amplifiers from small FBT powered monitors. The boxes were in bad condition and the 10'' full range drivers burnt, but the amplifiers were in perfect condition. I put them together to make a stereo power amp. The box is very simple made from scrap wood. Power switch, rca's, speaker outputs and ready to go. I also made for him a pair of speakers, i will upload photos to the proper forum.
Gainclone LM3886 @ 24 - 0 - 24 V
Analog input
Optical input
Bluetooth AptX Adaptive (Qualcomm)
3D Printed I/O back panel.
Heatsink: the entire chassis.
Analog input
Optical input
Bluetooth AptX Adaptive (Qualcomm)
3D Printed I/O back panel.
Heatsink: the entire chassis.
Very Nice and lovely Amplifier body
What's the VA rating for that toroidal transformer, that is very compact and it's very nice
Today I finally finished the preamp for the MM (Actidamp MK3). I think it's the best that can be built today. In the first stage discrete symmetrical amplifier with 2sk170bl on the input. Active damping + 2x dc servo, + passive correction in two stages.
