Valve phonostage build

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Neal
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Re: Valve phonostage build

Post by Neal » Sun Jan 14, 2018 11:25 am

Looks to be the same cct as the WD phono2/3 and the MJ one. Should sound good. Responds well to a good PSU and CCS on the front end.
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Re: Valve phonostage build

Post by Bigman80 » Sun Jan 14, 2018 11:48 am

CCS?

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pre65
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Re: Valve phonostage build

Post by pre65 » Sun Jan 14, 2018 12:01 pm

Bigman80 wrote:
Sun Jan 14, 2018 11:48 am
CCS?
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Re: Valve phonostage build

Post by Bigman80 » Mon Jan 15, 2018 12:39 am

Ah! Not up with the lingo yet 🤣

Thanks.

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Re: Valve phonostage build

Post by Bigman80 » Mon Jan 15, 2018 2:11 pm

This might be a daft question but forgive my naivety. I am new to this.

Is using a square wave the best way to judge and alter the RIAA equalisation? I also hope that makes sense 😂

Neal
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Re: Valve phonostage build

Post by Neal » Mon Jan 15, 2018 5:03 pm

Nick will know but I would have thought a better way is to use a reverse RIAA board/test setup to check the response...

https://hagerman-audio-labs.myshopify.c ... iaa-filter
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Re: Valve phonostage build

Post by Neal » Mon Jan 15, 2018 5:17 pm

Seems you can use a Square Wave in conjunction with a Reverse RIAA stage

http://hifisonix.com/wordpress/wp-conte ... e-RIAA.pdf

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Re: Valve phonostage build

Post by Nick » Mon Jan 15, 2018 5:42 pm

Yes, a square wave and inverse RIAA is a good way, but will only get you so close. Also remember you need to limit the rise time of the input square wave else the inverse riaa will try and turn them into very very large spikes that will distract you.

After that a frequency and phase sweep with the inverse riaa is the next step.
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Re: Valve phonostage build

Post by Bigman80 » Mon Mar 05, 2018 12:33 am

Hi guys

A little late in reply but ended up haven't to make a few modifications to get the sound where I wanted it. The phonostage is in a case and up and running. Sounding very acceptable but with a little bit of noise from the transformer. I've had a JFET input fitted as I just couldn't find an affordable SUT or HA that I liked.

Further mods to be done are to remove the Transformer from the case as I'm getting a mechanical buzz and some noise and then on to the RIAA.

The Square wave is ok, a little rise at the right of the wave, which to my ears is boosting the bass a fair bit. Obviously, it's going to need a bit more fettling.

The iRIAA kit looks interesting, I'll have a look at that.

Thanks for the responses and advice. It's appreciated.

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Re: Valve phonostage build

Post by RhythMick » Mon Mar 05, 2018 7:53 am

Rod Elliot has a simple design here.. I've not tried it.

http://sound.whsites.net/project80.htm

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Re: Valve phonostage build

Post by izzy wizzy » Mon Mar 05, 2018 8:51 am


Bigman80
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Re: Valve phonostage build

Post by Bigman80 » Tue Mar 06, 2018 12:17 am

Cheers, 😊

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