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 Post subject: Re: Hiraga MC pre-preamp
PostPosted: 28 Jan 2012, 07:40 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
Spent a night with 10 others at the home of the guy (Nick) who I built the tube phono preamp and Le Pacific MC preamp. It was a jazz night and we kicked off with a Sonny Rollins track. The Karat 17D3 Dynavector cartridge (nick's) melded perfectly with the Le Pacific MC preamp and Tubecad designed tube phono preamp. It couldn't get any better.

Late in the night we changed to the Hirage MC preamp (I took it along hoping we would get a chance to try it). It was far too bright in his system and was over-driving the tube preamp. But the Le Pacific was a real winner. In my system the Hiraga works a lot better with my AT-F3/MKIII MC cartridge. In fact I'm thinking of purchasing a Dynavector cart. myself. Hopefully it will work better with my BHL phono preamp and system.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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 Post subject: Re: Hiraga MC pre-preamp
PostPosted: 29 Jan 2012, 01:21 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I took Matt's suggestion and tested the impedance of the Hiraga MC stage. Due to a cheapo sig. gen. getting low voltages even with a resistive divider networks was hard. But as far as I could tell the input impedance is about 100ohms. Some MC carts. say loading should be under 1000ohms. It is definitely that.

I compared it with a Le Pacific which I known is 100omhs and it presented similar characteristics. The Hiraga certainly sounded spot on for my cartridge anyhow. I am looking at purchasing a Dynavector Karat 17D3 which sell here for about $1000. Time will tell though another club member also has the AT-K3/MKIII (which I have) and thought it excellent. ????????????

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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 Post subject: Re: Hiraga MC pre-preamp
PostPosted: 31 Jan 2012, 02:34 
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I purchased a Ortofon Rondo Blue to go with my Rega Panar 3 and RB300 arm. This will replace my Grado Wood body Reference. The Hiraga sounded too bright and forward with the cart. but according to the Rondo specs the load to the cartridge should be 50ohms or lower. The Hiraga has a much higher impedance than this. Looking at the schematic there is no reason why I can't drop a 50ohm resistor across the input of the Hiraga input. Or better a 100ohm and 50ohm on jumpers. I could select 50ohms or 100 or the two in parallel to provide less than 50 ohms.

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Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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 Post subject: Re: Hiraga MC pre-preamp
PostPosted: 31 Jan 2012, 21:19 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
I have installed the cartridge load selection switch which will give me: 220, 100 and 45phms load when the switch is in one of three positions (see image). I have read two different recommendations for loading of the Ortofon Rondo Blue. One for 100 and another for less than 50ohms. Currently I've loaded the cart. to 45ohms. No longer is the orchestra trying to jump out of the speakers and the excessive brightness has gone. Much better.
Attachment:
HiragaMCLoading.jpg


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_________________
Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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 Post subject: Re: Hiraga MC pre-preamp
PostPosted: 03 Dec 2013, 21:08 
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Joined: 06 Jun 2008, 18:23
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Location: Australia
A funny story. I changed the batteries in my Hiraga MC preamp. I then went to play an LP I had not played for many ears. All vocal was off in the distance and hard to hear. I blamed a poor recording. And played something else which had no centre speech but I put up with it again blaming the recording.

I noticed every time I touched the preamp it hummed. A few days later I was playing another LP I knew very well. It sound tinny and vague. The penny dropped. An earth wire joining the cct. Brd. to the ground of the RCAs and earths the enclosure had broken off while putting the enclosure back together. Easy fixed but it took a couple of LPs before I realised what had happened.

_________________
Projects: "Sanctum" - 12AU7 and 6AS7 direct coupled headphone amp | "retro-Oatley 6J6" - 6J6 push-pull headphone amp with OPTs | "Mimic Carbon" - carbon resistors and PIO caps. MM phono preamp
Website: retro-thermionic


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