MF A1 Clone

[dhengkoel]

Dear All;

Can we start to clone the Musical Fidelity A1 now?
I plan to make the MF A1 clone and combine with modified DOZ pre-amp.

regards:
ragil.hastomo

 

[Zen Mod]

probably you know that already....
http://www.tcaas.btinternet.co.uk/

with or without thread, here on DIY we can find plenty informations of A1

I cloned A1 before 12-15 yrs (I can't remember exactly...)
if you have any question,I'll try to answer....

 

[lineup]

Can we start to clone the Musical Fidelity A1 now?
I plan to make the MF A1 clone and combine with modified DOZ pre-amp.

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

Mark Hennessy has a lot of good info on Musical Fidelity A1.
He has done some tweaking/modifying.

http://www.mhennessy1.f9.co.uk/mf_a1/index.htm

 

[Zen Mod]

dhengkoel
if you want-I'll send you pcb pattern and parts placement ;
in handwriting,ages ago before (at least - mine) software pcb tools


I didn't bother with A1 preamp part-it's pretty bad,comparing to power amp part

this days,I'll go just with Mini A,or A100 at least (more Voltage and Current through output ) .

 

[Herrmann]

Hi

Choky: I would be interested in your pcb pattern as well.

Can anybody explain how the quiescent current is controlled in the MF-A1?

Regards, Torben

 

[Zen Mod]

Hi

Choky: I would be interested in your pcb pattern as well.

Can anybody explain how the quiescent current is controlled in the MF-A1?

Regards, Torben

I told ya that this pcb is pretty crude

tonight I'll upload it to my www,and post exact link here

go to hennesy's and read-I think that you'll find needed info regarding currents etc

if not,I"ll try to explain here

 

[Zen Mod]

http://czsr_bac.on.neobee.net/MF A1.zip

or via
http://choky.on.neobee.net/various.html


about 380 KB zip file
schematics is in fact more of informative nature-during scan process maybe I deleted something; didn't checked;
anyway- consult other schematics from mentioned sources

part designation and BOM are based on actual MF original PCB markings


schematic is upside-down ,contrary to convention - I place minus supply line on top,and plus on bottom

just came in tat way when I drew it from dismantled amp


worth to mention:
origigi PS is more than wimpy
for ~ 80VA of dissipation,you must use at least 300VA tranny,not 80VA as in original A1
10mF-0,47E-10mF (all that twice-for + and - ) is barely enough for both channels

if you use the same just for one channel,amp is dead silent with ear on cone-no hiss,no hum.....just pure blackness...... sorta silence gene??!

input elcos changed to blahblah Wima something
all resistors mf 1/3W ,except few wirewwwwww and few 1Watters for drivers

zenners-plain vanilla 1W3


etc

piece of cake

I was interested in CCS-ing one half,even bothered Papa Nelson with that,but-fortunately-he is busy enough and I'm not interested any more in that solution

build A1 or ,preferably,A100- just from memory-around 2x 33VDC and 1A3~1A5 through output stage

must be better ,but-then we are almost in bigger Alephs and KSA50 area....
anyway-nice little amp-maybe is still best solution to make it plain A1 with beefed PS, to keep it cheap and small.....

 

[dhengkoel]

Dear All;

thanks choky, lineup, torben for your replies and information

i've already ordered the pcb's (i'm not make it myself), but that's not finished yet ..

choky:

I didn't bother with A1 preamp part-it's pretty bad,comparing to power amp part

so i use DoZ preamp ..

http://czsr_bac.on.neobee.net/MF%20A1.zip

or via
http://choky.on.neobee.net/various.html

i can't get your file

torben:

Can anybody explain how the quiescent current is controlled in the MF-A1?

i think from r6 and r11, i will try it as soon as possible my pcb's ready ..

thanks & regards:
ragil.hastomo

 

[Herrmann]

Hi

Choky, your ZIP-file seems to be corrupted - will you please try again.

Torben

 

[kartino]

dhengkoel,

Opo kabare rek?? (LOL, our native......).

Do you a fan of class A? I would like to ask how good your last class A. I am currently on test of 100W class D, mail me private to kartino@inbox.lv if you interested.

Monggo mas.....(**)
Kartino

 

[Zen Mod]

I'll check tonight
last night I downloaded it OK for test

 

[dhengkoel]

mas kartino,

bener sampeyan teko gunungkidul? hwah aku 6 taon nang lereng gunungkidul, nang piyungan, tapi saiki wes nang sidoarjo, jawa timur ....

yes i am a fan of class a, but this is my first class a project, jlh for next project .... my recent amplifier is sc480 (silicon chip) and lm1875 chipamp, i use 2 way active x'over (astral), and drive 2 way bi wire speaker .. i use 6 inch 'curve' 618 and dome 'curve' tweeter (both produced by sinar baja surabaya) .. later i will use mf-a1 for midbass and tweeter, and sc480 for my 2x8 inch woofer (work in progress) ..


regards:
ragil.hastomo

 

[Zen Mod]

just uploaded again
tested
ok

 

[Herrmann]

Thanks Choky!

It works OK now.

Torben

 

[jaycee]

The A1 technically isnt Class A, it's just really highly biased Class AB. I'm not sure i'd choose this design now, the seperate feedback paths and input filters just scream poor symmetricity.

Probably best just to build something like the Krell KSA50 clone and bias it high

 

[Zen Mod]

jaycee
depending of your needs
look at this:
http://www.diyaudio.com/forums/showthread.php?postid=845666#post845666

 

[jaycee]

Well I was mainly just thinking along the lines of a similar topology thats more reliably designed. Personally, Class AB is enough for me

 

[dhengkoel]

my MF A1 PCB's still in work in progress, i think it's too long

but here is the DoZ preamp schematic that will replace the A1 preamp.

regards:
ragil.hastomo

 

[dhengkoel]

.. the pcb and component layout ..

sorry for bad picture, i get picture from scanner
i will try this amplifier as soon as possible ..


regards:
ragil hastomo

.. here the component layout ..

 

[dhengkoel]

.. here the bottom layer ..