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 Post subject: Shivers
PostPosted: 20 May 2016, 17:33 
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Location: Arizona, USA
Hi Everyone, It was hard to tell where to put this as it answers a question in the tube section. (Gio feel free to move it).

Shivers, AKA prickly hair on the back of the neck when listening to music

This is a phenomenon that I’m sure many of you have experienced. It happens when you least expect it while listening to your stereo. At least I hope your system and choice of music causes it on occasion, mine has. Today I finished the 6th iteration of the Groove phono preamp. It has been a long journey. Approximately 8 years if you count the flub ups during the first 18 months (bad). The posted project is really nice but I thought I could do better. In the 6th iteration, the basic circuit is unchanged, but a number of components were altered that slightly changed the operating points for the tubes. I also used Audyn True Copper Caps for the inter stage and output connections. They are sort of my new “best” one. The last two stages of B+ filtering now use Jantzen poly caps in place of the electrolytics. I used Mu metal to separate the active part of the circuit from the power supply. It was also used to cover the power transformer, AC mains input and power switch. The rest of the components are about as you would expect, capacitors by Nichicon, Wima and Panasonic, resistors in the active circuitry are bulk (I get them in bulk) carbon film with metal films in the power supply. In the RIAA area I used 1% Dale metal film resistors. The capacitors there were hand selected and matched. Tubes right now are actually the weak link as all I had was new production Tung-sol 12AX7s for the first two stages and a NOS Sylvania for the cathode follower. Even with the T-S tubes it sounds wonderful. BTW you can swap the 12AU7 for a 12AT7 (ECC81 etc) and the circuit values do not need to change. Both sound nice there.

So where does the shiver come in…. all the time with this preamp. It is dead quiet and has great detail, soundstage and response. The sound presentation is as awesome as any I have heard. Now I do grant that the preamp is only one part of the system. The rest is equally high quality. Starting with a Dynavector Ruby Karat 23RS-MR (a really superior cartridge), a Jelco unipivot tone arm, a much modified Dual 701 turntable (actually just the drive and controls remain), the new Groove, Lundahl SUTs, a remote control Forewatt, a pair of KT120 Oddblocks and a pair of Martin Logan ESLs. On occasion I hook up a pair of 7.5 cubic foot subs driven by a pair of class T amps. If I shiver any more I’ll freeze up. That is a really difficult thing to do in Arizona.

I will eventually post a new schematic with all the changes and the nice part is that earlier Grooves can be updated. You might run into a problem with the capacitors though as the Audyns are huge.

Good listening
Bruce

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 Post subject: Re: Shivers
PostPosted: 19 Mar 2017, 13:58 
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Joined: 14 Jul 2014, 13:18
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Location: Arizona
Bruce,

Thanks again for all the information and knowledge you share here. It is very much appreciated.

You mention using Jantzen poly caps in the last two stages of B+ filtering - are these the 100uf 400v Jantzens? So in place of the electrolytic/poly pairs, you use the 2 Jantzen poly caps? I ask because the Jantzen caps I've seen are some of the biggest poly caps I've encountered.

Thanks!

Phil


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 Post subject: Re: Shivers
PostPosted: 19 Mar 2017, 15:01 
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Hi, The latest version used only a 47 uf in the final filter stage. Previous stages are still electrolytics (100uF). I replaced the 47uF with pairs of Jantzen 20 uf CrossCaps. They are the second from the bottom in the line from Jantzen and are actually pretty decent. Another good option is the Audyn Caps Plus. Neither are expensive but both are pretty large in size. For the output coupler and mid stage coupler I used the Audyn True CopperCaps. A bit pricey and certainly physically large but IMO worth it. On a budget, I would try the Caps Plus in those locations as they are pretty nice sounding. What you don't want is really cheap caps that may color the sound. I have a batch of "Audiophilers" (pretty orange ones) that while cheap are not good for much. I don't even like them in power supplies.

Good listening
Bruce

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 Post subject: Re: Shivers
PostPosted: 20 Mar 2017, 19:33 
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Ok, I understand now. I was confusing myself as usual.

For the Jantzens - are you talking about the standard Z-caps (blue) or the Cross-caps (black)?


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 Post subject: Re: Shivers
PostPosted: 20 Mar 2017, 21:29 
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Hi, I use the Cross Caps in the power supply both as the final filters and as the 0.1uf bypass caps across the other electrolytics.

I have had good results with Panasonic polys for bypass as well.

The Silver Z Jantzens are one of the best (IMO) for coupling, but I like the Audyn True Coppers more. FT-3 Teflons are next in line.

Good listening
Bruce

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