PASS 50W single ended mosfet amp.

What people are working on at the moment
Cressy Snr
Amstrad Tower of Power
Posts: 10552
Joined: Wed May 30, 2007 12:25 am
Location: South Yorks.

#361 Re: PASS 50W single ended mosfet amp.

Post by Cressy Snr »

These buggers ought to drive your Quads beautifully.
Sgt. Baker started talkin’ with a Bullhorn in his hand.
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#362 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

Cressy Snr wrote: Mon Jun 25, 2018 4:21 pm These buggers ought to drive your Quads beautifully.
Hopefully. :)

Although when I took them to Owston in 2017 (with the baffles) no one seemed at all interested in them. :(
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
Cressy Snr
Amstrad Tower of Power
Posts: 10552
Joined: Wed May 30, 2007 12:25 am
Location: South Yorks.

#363 Re: PASS 50W single ended mosfet amp.

Post by Cressy Snr »

Whaddya expect?... They're TRANSISTORS! (horrors) :shock: :D

Solid state is fine though. My NVA clone is going to Owston and Ed has some interesting SS gear to show, I think. Then there is the terrifyingly expensive Soulution thingy, so you never know :wink: ....
Sgt. Baker started talkin’ with a Bullhorn in his hand.
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#364 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

Oh the heat !!!!

Anyway, finally got both A & B tested, and now set up in the system with the ESL57s.

I'll need a few hours to get a firm opinion, but first impressions are good. :D

PS For Eds edification, can't hear the two cooling fans. :wink: :lol:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#365 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

Well, after a few hours testing I'm happy that these single ended mosfet amps work well with the ESL57s.

They seem to go louder than the GK-71 amps, no surprise really, but a "bigger" sound as well.

Sitting here, with a glass (or two) of chilled crab apple wine, listening to the Lark Ascending.

Sublime. :D
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#366 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

I've finally managed to get the amps on my rack.

The amp parts are on the bottom shelf, pulled out frontwards so the heatsinks are not covered by the shelf above, and the overhanging front held in place from the floor by supports made from bits of scrap BBP.

Just got to make up slightly longer connecting wires and plumb in the 12v supply for the (silent) cooling fans.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#367 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

Two steps forward, one step back. :lol:

Got everything in position and wired up now. Great sound.

Trouble is now, got a slight hum on both speakers. :(

I'm sure it's because of the way the amps are now positioned, the curse of racks.

More thought required.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#368 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

I've had one of the amp portions on the workbench, have moved the input transformer about three inches further away from the power supply, and tidied up the wiring a tad.

I'ts now on test and no hum is noticeable. :D

Must do the second one now.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#369 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

Second one done.

However, there is still a little hum, slightly more on B than A. :(
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#370 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

On the output of these amps is a 10,000uf cap bypassed with a 10uf cap.

Would these be considered as "floating" ?

This question was asked because of a Nick G post on HFS.

Circuit diagram is on page 24, 3rd post down.
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Nick
Site Admin
Posts: 15706
Joined: Sun May 06, 2007 10:20 am
Location: West Yorkshire

#371 Re: PASS 50W single ended mosfet amp.

Post by Nick »

Sort of, yes, but the signal level at that point will be large, so its unlikley that its the cap picking up a hum field. Also the output side of the cap is connected to ground via the 8 ohm of the speaker.
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#372 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

I need to make it easier to couple the two parts of each monoblock together to

A) Minimise floor space.

B) Eliminate transformer field caused hum.

Then they would be easier to set up and use. I'd like to bring them to the next Owston. :)
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
pre65
Amstrad Tower of Power
Posts: 21373
Joined: Wed Aug 22, 2007 11:13 pm
Location: North Essex/Suffolk border.

#373 Re: PASS 50W single ended mosfet amp.

Post by pre65 »

I've finally made a start to make each monoblock take up a single floor space.

Double deck is the idea, I sort of know how they might end up. :lol:
The only thing necessary for the triumph of evil is for good men to do nothing.

Edmund Burke

G-Popz THE easy listening connoisseur. (Philip)
User avatar
Mike H
Amstrad Tower of Power
Posts: 20157
Joined: Sat Oct 04, 2008 5:38 pm
Location: The Fens
Contact:

#374 Re: PASS 50W single ended mosfet amp.

Post by Mike H »

Image watching.
 
"No matter how fast light travels it finds that the darkness has always got there first, and is waiting for it."
User avatar
IslandPink
Amstrad Tower of Power
Posts: 10041
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

#375 Re: PASS 50W single ended mosfet amp.

Post by IslandPink »

pre65 wrote: Fri Apr 19, 2019 3:01 pm Double deck is the idea
You could consider the 'Boost' - slightly rippled, with a flat underside.
"Once you find out ... the Circumstances ; then you can go out"
Post Reply