The Av800, how good is it?

When I searched the archives on this amplifier,
Holton (the designer) says they are good and no reported
problems in the field for years

I took a leap of faith that is works good
and started pcb layout for my version,
but I won't start construction for a while.
I'm going to gamble that the design
can drive 14 transistors per rail maybe
as high as 20. The standard design is
7 per rail up to 10 for the kilowatt version.

It seems like a classic design with
an extra buffer stage to drive more
output mosfets and differential input stage.

I suppose you can build a smaller
version with a few outputs to hear
what is sounds like, then scale upward
(voltage and transistor count) as needed.

i have 2 of his boards that i bought from him i plann soon later on to build the 2 amps up. Dont rely on anthony for help though he never replys to emails at all regarding his product for tech help or any thing. it is like he vannished. but i and another member can help you.. it is going to be expencive project but powerfull and lots of head room. : O )

Headbanging icon under your name. Is he listening
to Slayer? hehe

no he is banging his head because his PC keeps crashing. so he bought a mac and now it doesn't freeze at all now.

Giving X86 PC's an unjustified bad name.

JasonL said:

no he is banging his head because his PC keeps crashing. so he bought a mac and now it doesn't freeze at all now.

Click to expand...

It's not the PC that's evil, it's the O/S.

i know...!

That voltage transformer is perfect for bridging 2 av800 amps. You would get around 1kw into 8ohms..

natten said:

thylantyr,
would you mind "giving" me the pcb layout when you are done with it. I have never tried to do a pcb before you know.

Click to expand...

I just finished pcb layout for a version
of the AV800 I call model 2800.

I can give you the gerber files and you
can seek your own fabrication house,
but keep in mind, I have not built the
design yet.

I have plans to layout different
versions as follows;

Model 2000 - 20 output transistors
Model 2400 - 24 output transistors
Model 2800 - 28 output transistors
Model 4000 - 40 output transistors

These are single channel boards.
The AV800 schematic as shown
on the Aussieamplifiers.com website
was tested with 20 outputs, so
I don't know 100% sure if the
buffer stage can drive more than 20,
we shall find out... heheh

My layout is very exotic and I'm
thinking that it will be expensive
because it's a 4 layer PCB.

I have some extra goodies in
my PCB layout not shown in
the AV800 design.

Here is a comparison of my PCB
layout to the AV800 PCB/schematic.


****************
Model 2800 PCB: 6.5" x 10.75"
AV800 PCB: 5.5" x 10.5"

Model 2800 PCB- Protection circuits w/ DPDT relay (parallel contacts).
AV800 PCB - none

*Output short circuit,
*DC offset
*Temperature switch input
*Rail Detector
*External Load Detector
*Rob Elliot clipping detector.
*All the protection circuits have
enable/disable DIP switches for
each input
*Rail Detector may also work as a
"Turn off muting" circuit under certain
conditions.

Model 2800 PCB- Supports Molex Mini-Fit Sr.
connectors for speaker output and power input. Two pin for speaker,
6 pin for power input. Six was
chosen to allow parallel contacts.
Each contact rated for 50A.

AV800 PCB - no connector support.

Model 2800 PCB - Supports 750mil diameter
power supply capacitors on board,
such as Panasonic FC 680uf / 100v
capacitors, 14 total per rail (9520uF)

AV800 PCB - Supports six 47uf capacitors (282uF) per rail.

Model 2800 PCB - Supports three
750mil diameter "VAS/Buffer"
capacitors, typically three 680uf
capacitors per rail (2040uF), the same
ones used above.

AV800 PCB - Supports 220uf per rail.

Model 2800 PCB - Four layer PCB,
top and bottom are signal routing,
mostly on the bottom layer. Inner
plane 2 is speaker output, inner plane
3 is +V, -V, GND with esoteric GND barriers to channel ground current away from signal grounds, a strange
"plane star grounding" method.
Additional +V and -V tracks on the top
layer, and extra PCB real estate will
be copper flooded ground.

AV800 PCB - Single sided pcb. All routing on bottom layer.

Model 2800 PCB - Supports large capacitor footprint to allow the use of
polypropylene capacitors and one
Black Gate "feedback" capacitor or
equivalent.

AV800 PCB - Supports standard small
footprint capacitors.


Model 2800 PCB - Supports standard
input signal terminal blocks, 3 pin.

AV800 PCB - no connector support.

****************

As you can see, it's been a challenging
job to fit all these extra goodies
on a PCB that is slightly larger (by 1 inch) over the standard AV800 PCB.

The protection circuits are all surface mount devices, all components mount
on the top side.

All I need to do is to flood the top/bottom layers with ground,
triple check the nets. If you want
gerbers, send me an email. You
can download a free gerber viewer
to check it out.

DIY only.

natten said:

is it hard btw? if you got the schematic can the program (i.e orcad ) make the pcb by it self if you like say that you want the mosfets here and there

Click to expand...

The software I use is this;
http://www.mentor.com/pads/powerpcb/

There are many ways to do PCB layout.
You can create a schematic and
import the schematic into the PCB
layout software. Then you manually
position the components as needed.
You can route the nets manually
or you can use an autorouter.

For this particular design, I manually
imported the library components
and manually connected the nets.
Everything is hand routed, no autorouter.

This is the autorouter that I use.
http://www.mentor.com/pads/blazerouter/


For the cool factor, I also use this
software package to check "signal
integrity", typically crosstalk problems
are flagged by this software.

http://www.mentor.com/hyperlynx/index.cfm?pads=yes

I did draw schematics of all my circuits
on an old version of Orcad, but it wasn't used with the layout software.

i wonder what it is going to cost to get a av800 working. i can see that it is not going to be cheap. Will be a nice amp though. My other problem for me is heat sinks for that dam thing it is going to be hard because i live in canada. So yeah. And plus i'm building mono Block's so that adds to the cost.

Well, I just got a vision today...
20 of those Model 2800 inside
a 24"H x 24"W x 72"L chassis
on casters with ten 2kva toroidals.
All 20 channels bridged for 2kw@8 ohms,
so essentially it would be a 2kw x 10
channel amplifier.. doh 20kw.
This would power my 22 speakers well
(two cabinets).

Dr. Insano DIY projects........

560 output stage transistors..

The Devil must be driving this project, it's driving me mad.....

Thylantyr,

Seriously, try to get a group buy together. Anthony's PCB's are $50 each, and if you can get your PCB's w/ all the goodies less than that w/ a group buy, I'll bet quite a few people would be interested. Call a PCB place and get quotes for different quantities. I'll bet quite a few people would be interested.

-Matthew K. Olson

I haven't had time to call around for PCB pricing because I'm not really
ready to build.. My cash is going for the
speaker project right now. PCB
layout doesn't cost me anything
except time... hehe

If you want the gerbers, feel free to get
quotes, I just don't have the time
and energy to organize group purchases,
especially for something that I have
not even tested. Even though the PCB
layout "seems" ok, who knows
what gremlins might show up. I don't
want to be responsible for such a catastrophe.. I'd rather buy myself,
test, then provide gerbers.

The PCB house we deal with is high-end,
high quality. They can do some crazy
stuff like 30 layer boards, 3-5 mil trace/space, high cost. I'm sure a place
like this will charge no less than $150
per board.

I really have no sources for affordable
PCB fab houses. I tried to layout the
design with loose rules to allow
easy fabrication. I'm using 20 mil traces/24 mil or greater space for
the amplifier section, 12 mil trace, 12mil
space (worst case) for the SMD protection circuits.

Model 2800 PCB pic.

Red = top layer (component side)
Green = bottom layer (majority routing)
White lines = top silkscreen
Grey tracks = split plane isolation (inner layers)

http://home.pacbell.net/lordpk/Model2800/model-2800.jpg

The only bummer is... vertical mount
power resistors... Either you have to
bend one of the leads of your
favorite 0.22 ohm resistor or you
can buy a Ohmite radial resistor
(wirewound), it fits perfect.
Radial mount saved me alot of PCB
real estate, otherwise it would be
difficult to get all the features I wanted.

Holton's AV800 .. scanned image of
component side.

http://home.pacbell.net/lordpk/AV800PCB/Av800-2.jpg

Jeez. Ok, here's my thing. Suppose I want to make it monoblock....I have to mount the PCB in the middle, and the use flying leads out to both heatsinks....unless both heatsinks are exactly the proper distance appart and then I can still use the pcb for mounting the outputs. Otherwise, it all has to be mounted on one big heatsinks (those I have...but I want to make an amp symmetrical ...heatsinks on both sides. So therefore I'd need to make it a stereo amp and bridge it for HUGE power. Shame In any case, I just don't like the idea of mounting the outputs right to the pcb. My preference and no offense meant. Looks sweet though. Please test it, get boards, and sell sell sell!

-Matthew K. Olson

but ps, you might want to make it optional (have a smaller pcb somehow) to have driver boards and output boards :-D

natten said:

thylantyr, your project is very interesting!!
I would order parts today if i had the money. I am working this summer so i should have som money soon.

Do you think a 2kVA 2*48 V AC will be enough? i can get it for like 60 $ so it would be perfect if i could use that one.

How much does it cost to get the pcb manufactured? i guess that more pcb's will make the cost per pcb go down

Click to expand...

It would work good, but a penalty
in output power as you lower
rail voltage.