A Directory of Apex Audio Amplifiers

[xrk971]

Hello xrk971
greetings thank you for pointing out the omitted 100 pf caps on my pcb
FH9 HV can a another pair of output hexfets be added to the existing
schematic for +/- 50 volt dc rails for 4 ohm speaker loads hexfets are
cheap
warm regards
Andrew

I ran a single pair with 52v rails and it works great. I suppose since the hexFETs are voltage driven, the KSA1381 and KSC3503's can probably drive two sets just fine. I would have to simulate it first to get a feel if it will work, but my guess is that it would work. I think even single pair can drive 4ohm load just fine.

 

[xrk971]

Just ran across the A3 today, does anyone know much about this one or built it?

What does the op amp in the middle do - with no connections on the input or output?

An externally hosted image should be here but it was not working when we last tested it.

 

[thimios]

Just ran across the A3 today, does anyone know much about this one or built it?

What does the op amp in the middle do - with no connections on the input or output?

An externally hosted image should be here but it was not working when we last tested it.

Nothing,just this represent the power supply pins of mc33078

 

[Karl vd Berg]

SF 3.1 all-FET / SB 3.1 all-BJT preamp versions + photo

There're an all-Fet SF 3.1 preamp, and an all-BTJ S B3.1 version of it at page #6 of the http://www.diyaudio.com/forums/solid-state/164093-100w-ultimate-fidelity-amplifier-6.html thread, including some pictures of the preamp Apexaudio built in 1990... 😉

 

[xrk971]

Thank you Karl vd Berg,
I just updated the first page directory with the above 2 preamps and also a PAU + stereo protect circuit I saw on same page.

The schematics are really adding up so far! 🙂 Count is currently 43 schematics on Post 1.

PSU and Protection:

 

[xrk971]

Added FH11

http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-801.html#post4775467

Layout by Sonal Kunal (note typo on legs of MJE350 in middle of board):

Built and tested by Andrewlebon and Still4given, respectively:

http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-809.html#post4778364

http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-810.html#post4778451

 

[xrk971]

FH12 added

http://www.diyaudio.com/forums/soli...imate-fidelity-amplifier-816.html#post4780667

Not yet tested, but 99% certain it will work...

 

[xrk971]

Added BX22

http://www.diyaudio.com/forums/solid-state/164093-100w-ultimate-fidelity-amplifier-819.html

 

[Karl vd Berg]

AX6 - Retro Amp 50W (old single supply topology no need DC protect)

Post #1 - http://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply.html#post3497279

PCB board with integrated single supply, post #79 - http://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-8.html#post3518260

PCB board only, post #72 - http://www.diyaudio.com/forums/solid-state/236256-retro-amp-50w-single-supply-8.html#post3516554

On Youtube > https://www.youtube.com/watch?v=gFbivge6oVY

Below, Apex's 50W Retro Amp boards (no single integrated PSU)

 

[xrk971]

Folks,
I just updated the index post to include the FX7 and CA10 (new design untested current feedback).

I am running into a problem though, there is a max limit to 50 images linked in any post. So cannot add any more amps after this. I will ask the admins to see if they can give me infinite edit rights to post #2 so that we can extend this for at least another 50 images as Apex Audio is so prolific 😀

 

[Moderation Team]

Unfortunately altering the posting privileges for specific one off cases isn't really possible. From a practical user viewpoint, having dozens of images in a single post can cause issues with slow loading for those not on a fast internet connection.

Suggestions might be to group and categorise designs into years/topologies etc and perhaps have a master index linking to the different categories.

Great thread by the way 🙂

 

[us1070]

After using for many days Apex AX 14 i found flaws while comparing it with some of my Chinese aliexpress amplifier boards

I built Apex AX 14 with +-20vdc with elna filter caps and ei transformer but it does not sound smooth and sounded like attacking music. It was for Horn Driver. The Chinese AB Amp sounded smooth and nice with Chinese crap filter capacitor.

please see my image and tell what should be replace to make it sound smooth

 

[xrk971]

US1070,
What bias current are you driving with it? My first reaction is that the amp was not designed for +/-20v supply and running it thus, without modifying the resistor networks, does not supply sufficient current for the LTP, VAS, driver stages. You might be operating deep into the crossover distortion regime. Try a +/-35v supply and see if it sounds better. Perhaps Mr. Mile can suggest new resistor values for a 20v supply.

 

[xrk971]

Unfortunately altering the posting privileges for specific one off cases isn't really possible. From a practical user viewpoint, having dozens of images in a single post can cause issues with slow loading for those not on a fast internet connection.

Suggestions might be to group and categorise designs into years/topologies etc and perhaps have a master index linking to the different categories.

Great thread by the way 🙂

Hmm... that'a too bad. 🙁

It's going to take work to re-organize this into topologies or split into number of actives: 20 and below or 20 and above etc.

 

[AndrewT]

Existing index.
just add each new amp with a short description and a link to a post with all the detals.

 

[gannaji]

Existing index.
just add each new amp with a short description and a link to a post with all the detals.

This is the best method. The present 'post one' has become difficult to load and then to navigate. Please Let the first post be only 'index and pointers' to the actual posts.

 

[ammel68]

The Chinese AB Amp sounded smooth and nice with Chinese crap filter capacitor.

Which Chinese Aliexpress boards are you referring to?
Can you provide a link?

 

[smartx21]

Unfortunately altering the posting privileges for specific one off cases isn't really possible. From a practical user viewpoint, having dozens of images in a single post can cause issues with slow loading for those not on a fast internet connection.

Suggestions might be to group and categorise designs into years/topologies etc and perhaps have a master index linking to the different categories.

Great thread by the way 🙂

What about wiping out everything that isn't an amp design, like power supplies, preamps, protects et al?

 

[xrk971]

What about wiping out everything that isn't an amp design, like power supplies, preamps, protects et al?

That buys maybe 10 more before we run out of room again.

I have been thinking about this and probably make links with no images is easiest.

 

[ashok]

Start a new thread with the name
Directory of Apex Audio Amplifiers-Part 2
🙂