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Old 6th May 2004, 03:57 PM   #1
kmj is offline kmj  Sweden
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Default linestage needed

Hi again,
i just wondered if u gurus have any recommendation for a linestage/Riaastage.

will be used with a pair of 4xEL34-monoblocks in triode-mode.
The inputsensitivity is 1.6Vrms, inputimpedance 100kOhm.

For Details:
http://www.plitron.com/PDF/PB/Article/Atcl_9.pdf

Or will it perhaps do with a passive pre?

(some changes made, among other things the outputtrafo is hammonds "1650K" since the price is 70Euros instead of 277 for the "pat4004")....

hammond: http://www.tubetown.de/produkte/prod...-5c0051-52.pdf

pat4004:
Type and Application : VDV3070PP=PAT4004 4 x EL34
Primary Impedance : Raa 2.756 = [kOhm]
Secondary Impedance : Rls 5 = [Ohm]
Turns Ratio Np/Ns : Ratio 23.478 = [ ]
Ultra Linear Tapping at : tap 40 = [%]

So, Shoot

PS.
As simple and good as possible.
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Old 6th May 2004, 07:01 PM   #2
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With a 1.6 V. sensitivity, you don't need gain for CD (2 V. max. "standard"). Simply replace the 100 KOhm grid leak resistors at the amp's I/P with pots. Alps or Noble conductive plastic parts seem indicated for a "budget" project, such as yours.

A phono stage with 50 dB. of gain combined with a "typical" 5 mV. O/P cartridge requires no additional gain too. 50 dB. of gain applied to 5 mV. = 1.58 V. Peak signals on LPs will drive the amp into clipping without attenuation.
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Old 7th May 2004, 08:08 AM   #3
kmj is offline kmj  Sweden
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a passive preamp for the cd and phonostage then.

any schematic for the phono?

perhaps something along these lines?
http://www.svetlana.com/docs/TechBul...pnoteNo23.html
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Old 7th May 2004, 06:48 PM   #4
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[QUOTE]a passive preamp for the cd and phonostage then./QUOTE]

No, build the level control(s) into the power amp chassis. Pots. driving interconnect cables can be, and frequently are, trouble. In any event, you have to use 10 KOhm parts in an external passive control center. Some (many?) tube phono stages can't drive 10 KOhm loads. Again, that's trouble.

That EF86 gain block schematic does not address the IMPORTANT issue of RIAA equalization that all phono preamps MUST provide. Bruce Rozenblit (http://www.transcendentsound.com/) offers a design with the gain you need. You don't have to buy his kit. I believe that Bruce's "Audio Reality" book has the schematic in it. If phono stage costs are an issue, assemble a Hagerman (www.hagtech.com) "Bugle" configured for 50 dB. of gain. Even though it's an opamp based design, the "Bugle" sounds quite decent.
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Old 7th May 2004, 08:15 PM   #5
kmj is offline kmj  Sweden
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Thank you

I did acually find his page a couple of weeks ago and I started to look over the bugle right after i posted my reply. I think i will build that combined with the powersupply and then adding two more imputs (CD&Computer). And volume+linecontrol.
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Old 10th May 2004, 08:47 PM   #6
kmj is offline kmj  Sweden
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the monoblocks will be 2 physically separated.....eh, blocks
and since i want one volumecontrol i thought to make a passive pre.

is there no way to build an easy line+volumestage separated from the accual amp?

like:
turntable->RIAA->line+volume->amp
CD->line+volume->amp
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Old 10th May 2004, 11:42 PM   #7
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Quote:
is there no way to build an easy line+volumestage separated from the accual amp?
Buffer the volume control. A cathode follower with an active load (current sink) makes an excellent buffer. JJ's ECC99 makes an excellent cathode follower.
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Old 10th May 2004, 11:46 PM   #8
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Give this a look over. I built one. Have not tried the phono stage yet as turntable needs the motor replaced.


http://www.tubes4hifi.com/preamp.htm
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Old 11th May 2004, 12:16 AM   #9
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Hi,

If you need a dead quiet phonostage for MM or high output MC here's one I designed years ago:

PHONOSTAGE

In fact the thread also shows the tube regulated supplies and a buffered volumecontrol using a 12BH7A which you can replace with a ECC99 if you like.

The phonostage RIAA correction needs to see a g' of 1M in the next stage so you better build it as a single preamp.

The volumecontrol can be complemented with a linestage with gain using whatever you fancy...
I've already a few of those drawn up as headphone amps, if you'd like I'll post them.

The PSU doesn't have to use a tuberegulated supply but totempole configurations do benefit from a well filtered, stable supply as their PSRR isn't exactly great...

Cheers,
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