Randy Slone's "Fig 11.4" (Self's "Blameless"?): PCB layout

[sam9]

Looks a lot cleaner. However, there may be physical conflicts between C1 & R31. Also the following look like they will accupy thesame space as the small heat sinks: R13, R6, D4, C4.

Finally U$9 and u$6 look like the will interfere with one another.

 

[tcpip]

Looks a lot cleaner. However, there may be physical conflicts between C1 & R31. Also the following look like they will accupy thesame space as the small heat sinks: R13, R6, D4, C4.

Finally U$9 and u$6 look like the will interfere with one another.

All your comments are correct, but I'll be moving the components round a bit after I buy the larger heatsinks. At that time, I'll fit the layout to the heatsinks. In fact, I may switch back to small heatsinks for all the VAS transistors, if I operate at the recommended current rating of Slone (about 6mA, IIRC).

And about R38 interfering with C1, you're right. I'll fix R38 on the underside of the PCB if I have to... it's a simple thing to do.

 

[lineup]

good work, tcpip!


PS.
If anyone wants to try improve the CCS for input pair
in this Slone Amplifier
my post with 'the prefectionist's approach' is still here.

A few posts above:
The ultimate & simple CCS


lineup

 

[tcpip]

If anyone wants to try improve the CCS for input pair
in this Slone Amplifier
my post with 'the prefectionist's approach' is still here.

I'd put it into my current design, if I thought it'd bring in audible improvement or fix a weakness in the basic amp. Also, can you give some part numbers for the FETs?

 

[tcpip]

Do you want OPS protection on the amps you build?

Do the people on this forum usually want OPS protection included in the power amps they build? I see a lot of amp schematics floating around with no attempt to do output current limiting of any kind... so I was wondering.

For the kind of applications I have in mind, I can live without OPS protection, but I was wondering what the rest of you think, in general.

 

[AndrewT]

Hi,
I always recommend full IV limiting with fused rails for the longer term.

This will probably require DC detect and relay isolation of the speaker output.

Starts to take up PCB resource. (19 small components) just for IV

For a FET output stage many say that Zener protection of the gates provides sufficient current limiting to let the FETs survive with only rail fuses.

 

[john_ellis]

Hi Forr

Didn't get the reference you posted.

Hi Andrew T

Both these others refer to JLH's MOSFET design. THe one I mentioned used bipolars. Originally 2N3442's but think JLH forgot to read the data sheet on fT and picked them just for Vceo. These are really bad for audio. Later it was updated with BDY56's (~10 MHz). Probably his original would work with MJ15003/4 or even better with MJ21193/4.

cheers
John

 

[john_ellis]

Hi tcpip, edl and all

geoff has posted JLH's amplifier circuits. The one I was thinking of was
A Direct-Coupled High Quality Stereo Amplifier Part 1
HFN&RR
Nov ’72 p2120

which lasted a few articles until march 73.

This used bipolars and had phase-lead compensation.

I'm sure JLH would have been impressed by the transistors now available... we should rework his amp as an update.

cheers
John

 

[sam9]

For the kind of applications I have in mind, I can live without OPS protection, but I was wondering what the rest of you think, in general.

Probably the you can prevent the most common type of mishap by using insulated binding posts on both the amplifier and speakers and spade lugs or bananas on the wires. If you want to go further there are "SpeakOn" connectors. These won't prevent all accidents but they should reduce the risk quite a bit.

 

[Shaun]

@tcpip:

Did you get the 2 emails I sent you regarding my version of this amp?

 

[lineup]

I'd put it into my current design,
if I thought it'd bring in audible improvement or fix a weakness in the basic amp.

Also, can you give some part numbers for the FETs?

Yes, tcpip

You want your amplifier to be good to listen to.
Not necessarily have as good data as possible, using this circuit.
Good point to have in mind.

What is a 'weakness' in an amplifier is different for different people.
Using 2 resistors and trying to filter from power supply using 1 cap
may some consider a weakness,
if there is a better alternative.
Other will consider it not a weakness.
-------------------

I think you will find many JFET if search our forums.
For a CCS- current source it is not critical exactly which one.

> Also, can you give some part numbers for the FETs?

As I already mentioned 3 different JFET 'part numbers', if I recall.
Just scroll some posts up if you do not want to search forum for TO-92 N-JFET.
No problem find something suitable.


Lineup Audio Lab
lineup - Chief Designer & expert in fet current sources
http.//lineup.awardspace.com/

 

[john_ellis]

Hi tcpip, and all

THe amplifier circuit I was thinking of to show phase lead compensation is now on Geoff's website in the
JLH Direct Coupled amplifier thread.

Have a look at that if you want to see how JHL did phase lead.

Thanks Geoff!

cheers
John

 

[Kuzmenko]

back to initial post... do you think that Zhiklai output stage is "blameless"? Mua-ha-ha!

 

[Kuzmenko]

btw, there is no need for double-sided pcb for such simple design

 

[sam9]

btw, there is no need for double-sided pcb for such simple design

True, but no harm either. With double sided it is easier to keep the dimensions of the board down. This may be important if you are trying to squeeze it all into a compact enclosure. I've found on ocassion I boxed myself into a situation where fitting everything into the enclosure and wiring it was more challenging that than the amp PCB itself.

 

[tcpip]

btw, there is no need for double-sided pcb for such simple design

Yes, Randy Slone himself does a 6"x4" SS PCB for this design with lots of space between tracks and thick, easy-to-use tracks. I'd have done something similar if I had the luxury.

But can this circuit be laid out on a 3.2"x4" PCB single-sided? I believe I explained in my first post that the PCB size is constrained by Eagle's Light version.

 

[sam9]

I found that using miniature resistors (3.2mm rather than 6.5mm) that can be found through Digikey helps if you are constrained by board size.

 

[Kuzmenko]

3.2"x4" ?
6"x4" ?!
For example, i`ve fit this
[/IMG]http://images.people.overclockers.ru/109891.gif[/IMG]
into this pcb

The size is 38x45mm, most of them (~1/3) was taken by huge film capacitor, it`s PSU shunt.

PS if you think that your russian is good feel free to discuss it at http://www.vegalab.ru/forum/showthread.php?t=8840

 

[tcpip]

3.2"x4" ?
6"x4" ?!
For example, i`ve fit this
into this pcb

Till I know the schematic and BoM for that circuit, I really don't know whether it compares with this amp.

PS if you think that your russian is good feel free to discuss it

My Russian is non-existent.

Just curious... why did you need a large box-type cap for a PSU shunt? Isn't that what one usually does with electro's bypassed with small ceramics or other high-freq low-value caps?

 

[Thoru]

Hi people,

I hope this question is appropriate enough for this thread, but 'lineup' pointed me to here. I've build a Slone fig 11.4 amp using slone's pcb. I only modified it slightly to get some hum reduction. I actually modified it to follow Self's grounding and supply filtering recommendations.
The problem now is that when I connect some source to the input I get lots of noise and sometimes even loud repetitive plops. The sources are not playing. When I short the input to its signal ground it's very silent. Now I'm wondering where could the noise be coming from and how do I get rid of it?

Thanks in advance,

Remco Poelstra
P.S. my original question is here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=95499