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PostPosted: 28 Nov 2010, 12:16 
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Joined: 28 Nov 2010, 12:09
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Hi, I'm trying to make this project, but i couldn't found the ECC83 valve, the only one i could find was the ECC85, what alterations to the circuit should i do in order for this valve to work?

ECC85 datasheet: http://www.drtube.com/datasheets/ecc85-philips1969.pdf

i know the valve runs at 6V, instead of 12V, so i was thinking of putting a 6V input and change R3 and R4 for different ones, but i don't exactly know what changes to make, can you help me?

thanks


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PostPosted: 28 Nov 2010, 12:37 
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Joined: 18 Sep 2010, 12:48
Posts: 81
KrammeAcoustics wrote:
santik wrote:
ok, it is a 12VDC regulated power supply, full of hissing. It is mostly gone now... just very very low frequency hum/hiss after that capacitor circuit. So, you say that with resistor capacitor circuit the hissing will be gone, better? I do have 1Ohm 2W resistor, is that wattage rating sufficient enough? and for 1 ohm in 12VDC, how much voltage will drop?

1 Ohm will give a low voltagedrop, but that will probably not be enough.

No, you won't go that way. If the PS you've got, are already regulated to 12 VDC, it don't bring sense, to go for a even lower voltage, because the amplifier and filament needs 12 VDC.

As told before, go for a higher voltage ( another PS ) and filter it down to 12 - 12,6 VDC.

Explanation of the RC circuit, read about it here:
http://en.wikipedia.org/wiki/RC_circuit

yeah, I will lose current and voltage with that...

hmm... will try to dig out for a higher voltage PS.


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PostPosted: 28 Nov 2010, 18:17 
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Joined: 17 Apr 2010, 16:07
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Location: Huddersfield ,West Yorkshire,UK
KrammeAcoustics wrote:
Explanation of the RC circuit, read about it here:
http://en.wikipedia.org/wiki/RC_circuit

is this a suitable calc for working out the resistor and cap values Kramme ?

http://www.muzique.com/schem/filter.htm

Regards
Koogar

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Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp


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PostPosted: 29 Nov 2010, 12:25 
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koogar wrote:
is this a suitable calc for working out the resistor and cap values Kramme ?

http://www.muzique.com/schem/filter.htm

Hi Koogar

I don't think so ...it looks like this calculator is intended for highpass/lowpass amplifier input RC filters.

Instead i guess it should be interesting to look for "RC ripple filter calculators". Unfortunately the one, shown in the following link, doesn't contain larger values than 800 uF capacitors ( because the usage is intended for tube amplifiers "high voltage PS" ).
http://ampbooks.com/home/amplifier-calc ... le-filter/ ( plot data into the green box and calculate by using "Compute" ).

In the shown ill. you can see a voltage drop of 2,8 V and a draw of 700 mA current, ripple suppression is 7 db. If one more similar RC filter is connected ( do the math ), then it's a higher voltage drop and a higher ripple suppression.

Image

If anyone got links to a better "RC ripple filter calculators", please tell us. :up:


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PostPosted: 29 Nov 2010, 14:22 
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Location: Winnipeg, CANADA
SmittyHalibut wrote:
Koogar: thanks for that link! I'll give that a try on my HD555s and will report on it's effect.

Hi guys, this mod came up earlier as is discussed a little in this thread: Sennheiser HD555 upgrade to HD595.

Cheers

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PostPosted: 29 Nov 2010, 23:26 
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Joined: 27 Nov 2010, 02:18
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Location: Arroyo Grande, CA, US
KrammeAcoustics wrote:
I don't think so ...it looks like this calculator is intended for highpass/lowpass amplifier input RC filters.

Any reason you don't just want to regulate your supply? Regulation is great at rejecting ripple.

-Mark


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PostPosted: 30 Nov 2010, 06:26 
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Joined: 17 Apr 2010, 16:07
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Location: Huddersfield ,West Yorkshire,UK
SmittyHalibut wrote:
KrammeAcoustics wrote:
I don't think so ...it looks like this calculator is intended for highpass/lowpass amplifier input RC filters.

Any reason you don't just want to regulate your supply? Regulation is great at rejecting ripple.

Thanks for the link Kramme !

Mark ,
Because even if you regulate it with a LM317 with a lot of capacitance before the basic NP-100v12 amp you get HUM from rectified AC transformers and wall warts the only option at this stage is to use a switched mode PSU before the amp and even some of those can be noisy .

Also i would like to build an AC transformer into the chassis as i have so many things with external PSU's also then it would be fully linear :D

Had some good success today Kramme with a rectified AC transformer i thought i would try regulating it twice using two LM317's (one extra before my on-board LM317 PSU) the supply was silent :)

I used a 16 VAC 1A wallwart rectified it was 24.56v DC using the extra LM317 i regulated it to 17v then passed it on to my on-board PSU LM317 which regulated it down to 12.6

I originally tried it with a 24 VAC transformer but after rectification the heatsink i had installed got a little hot on the first lm317.

At the moment both regulators run cool at 40 degrees C each which is also a bonus.


PS: I dont mean to hijack Rogers thread with alot of talk regarding the PSU's but i still think its valid to people building this amp as not everyone has a lot of different PSU's to try and often we have to find solutions for things we have lying around :)

Koogar

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runawaybrainz.blogspot
Head Amp On 555 Delay all in one
NP-100v12 - 12AU7 / IRF510 HeadAmp


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PostPosted: 30 Nov 2010, 11:29 
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Joined: 18 Sep 2010, 12:48
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both will go though a line of parallel capacitors.
using a Switch Mode Power Supply will have less hum and hissing compared to Regulated Power Supply?


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PostPosted: 30 Nov 2010, 12:02 
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Joined: 18 Sep 2010, 12:48
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ok, let just say I like the sound of this tube A and also the sound of tube B; can we do 2 tubes as preamp? parallel to each other?

inputs to the gates of both tubes and the plates of both tubes to MOSFET. possible? logical?

I think the tubes are basically one way, like a diode. isn't it?


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PostPosted: 30 Nov 2010, 12:43 
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SmittyHalibut wrote:
Any reason you don't just want to regulate your supply? Regulation is great at rejecting ripple.

Hi Mark

There is no reason, not to ...go for it, try it. ;)

I've tried both, regulated PS, SMPS and RC filtered PS, for the NP-100v12. I think they all got both some good and bad behaviors. But if it comes to a choice of taste:
1. RC filtered PS ( in my ears, it's possible to create good sound )
2. SMPS ( no hum at all, but in my ears, boring sound )
3. Regulated PS ( i've tried LM7812 ...but like SMPS, i think it's boring sound )

When it comes to all, it's a matter of taste. Some people also like the sound of chokes in a PS, because they add something to the sound ( NOTE: i don't mean a choke is needed for this build. It's just to mention, that taste are individual from one person to another ).


Last edited by KrammeAcoustics on 30 Nov 2010, 14:24, edited 3 times in total.

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