• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Amplifier Modules and PCBs For Sale

Status
Not open for further replies.
Jump to Latest
D

Deleted member 148505

More "refined" version, final draft before sending to manufacturer.
 

Attachments

  • Final Draft.PNG
    Final Draft.PNG
    240.1 KB · Views: 574
D

Deleted member 148505

CharlieLaub said:
I noticed on the SKA web site they mention that the amp can be "converted" to deliver up to 50W into 8R under class-A operation. Can you board also be configured that way?
Click to expand...

CMIIW only resistor values are needed to be changed in order to operate it in high bias push-pull class-A mode. 50W into 8R requires 3.4A quiescent current, large heatsinking is needed and power supply should be very good, to be able to run it in class-a mode.

I'm using the "public" released schematic, but with individual source resistors for each mosfet. I also included the following features on the PCB:
  • Speaker Protection Circuit/Power on speaker delay.
  • MKT or Back to Back Electrolytic for Input Cap.
  • Input Capacitor can be bypassed by a jumper (like jumpers in computer motherboard/hdd).
  • Uses E-B-C small signal transistors. (2n5401/5551)
  • Thermal sensing transistors on top of Output Mosfets.

Regards,
Lester
 
DarpMalone

DarpMalone

Member
Joined 2008
Hi JLester. I'm hoping you can advise,

I have 2 of your Audiophile-250 boards, sharing an enclosure with 2 LJM L25D boards. Each amp channel has a separate, linear power supply, only connecting on the mains side.

I've had no issue sharing both JLAudio boards 12VAC off of a single transformer so I assumed that I could also use that transformer for another speaker protection board that I'm using with the L25D's which also takes 12VAC, however when I do I get an (extremely loud) 60Hz buzz through all amplifier channels. (ground loop?)... When I lift the earth connection, temporarily, nothing changes.

My temporary solution was to add another 12vac transformer to power the external speaker protection board. The buzz is gone, but I'd really like to simplify the layout as much as possible.

Can a single 12VAC supply with sufficient current not power the external SPboards as well as the JLA's?

Thanks

Sent from my Nexus 7 using Tapatalk
 
DarpMalone

DarpMalone

Member
Joined 2008
I laughed as I took this picture because visually its a mess.

You're correct. I didn't have the grounds tied together. I've just tied the ground planes together from the 3 sets of capacitor banks and I believe it has made the system a bit quieter on a whole, it didn't solve the buzz. With the additional transformer I only hear a clean hiss. When I combine the 12v I get the same loud buzz.

I doubt that this image will help. I'll try to draw a simplified schematic this afternoon.

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


Thanks
 
C

CharlieLaub

Member
Joined 2007
audio.claub.net
Paid Member
DarpMalone said:
Not related but I've just discovered that I've created a nice short in the way I mounted my torroids.

I'm changing the entire layout so please disregard this issue.

Thanks,
Justin
Click to expand...

That's right, you made a shorted turn. There should not be an electrical conductive path that passes through the center of the toroid and around the outside.

Mount the two transformers on top of each other with a single bolt down through the chassis bottom. This was done for instance on the Aragon 4004 MKII amplifier:
aragon.jpg
 
D

Deleted member 148505

A client requested me to replace the busted amp section of Krell kav-400xi.
The result: zero noise and very good sounding amp :)
 

Attachments

  • 15520111013_37cde6f120_b.jpg
    15520111013_37cde6f120_b.jpg
    183.1 KB · Views: 481
  • 15954074467_9b6706419c_b.jpg
    15954074467_9b6706419c_b.jpg
    421.6 KB · Views: 198
  • 16139081162_8d54a02d15_b.jpg
    16139081162_8d54a02d15_b.jpg
    363.2 KB · Views: 203
  • 15952530470_98072f1e54_b.jpg
    15952530470_98072f1e54_b.jpg
    192 KB · Views: 178
Status
Not open for further replies.
Top Bottom