LCR riaa's

the road not taken.
reVintage
Posts: 365
Joined: Fri Sep 07, 2007 9:54 am
Location: Sweden

Post by reVintage »

Thisis the ciruit-idea I was refering to:
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Brgds
Lars
reVintage
Posts: 365
Joined: Fri Sep 07, 2007 9:54 am
Location: Sweden

Post by reVintage »

Andrew wrote: I think you said about 1k DCR so that the Zout of the 5842 plus the 1k DCR and some added resistance to make 1k5 would give me a matched impedance to the 1k5 LCR.

-- Andrew
Maybe I am doing an error here but I think one has to take the overreflected DCRprim in account.

If we have a 1:1 bifilar with DCR 1k the Zout will be: 5842CFZout+DCRprim+DCRsec, ie +2k. If we use a stepdown of 2:1 with the same DCRprim and a DCRsec of 500ohm the Zout will be just above 750ohm. And the way I see it the loading should be at least 10*Zout.

So CFs and transformers is no great idea due to the influence of DCR.

If we use capacitor-coupling to the presceding stage this could be the way to bias the CF:
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Brgds
Lars
Andrew
Posts: 201
Joined: Wed Apr 26, 2006 8:06 am

Post by Andrew »

Hi Dave and Lars

Thanks for the replies and all the help and advice.

I'm beginning to be persuaded that the TX at this point in the circuit is not a good idea, it seems that it causes more problems than it solves. I will try Lars' AC coupled LCR just to avoid the DC on the chokes and to see if those few millamps on the chokes are causing any problems.

thanks for the help.

-- Andrew
Andrew
Posts: 201
Joined: Wed Apr 26, 2006 8:06 am

Post by Andrew »

The phono had an outing this weekend and although its is still a bit harsh and edgy in some instances it seems to have been well received.

I intend to get rid of the grid leak as I think that's perhaps one cause of my problems.

In any event, now that its stable and working its time to get it onto the test bench and see what I can see.

-- Andrew
IslandPink
Posts: 56
Joined: Thu May 12, 2005 8:01 am
Location: Denbigh, North Wales

Core !

Post by IslandPink »

Dave -
Just gearing up finally to get these chokes into a rebuild of my current phono - planning the layout etc .
I occurs to me I never asked you what the core materials were on these.
Can you remember ? - they were the same as supplied to Andrew as discussed here .

Have you got a new e-mail btw ?
( Your Earthlink one 'bounces' )
dave slagle
Posts: 2085
Joined: Sat Jan 22, 2005 3:54 am
Location: NYC
Contact:

Post by dave slagle »

Hey,

The cores are 80% nickel.

dave
Get Your Fix
www.hifiheroin.com
IslandPink
Posts: 56
Joined: Thu May 12, 2005 8:01 am
Location: Denbigh, North Wales

Post by IslandPink »

"We are not worthy"
Great !

I will bring them down from the cupboard to admire, as I am eating my dinner .
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