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Playing Vinyl on a TD-124

Posted 6th January 2011 at 08:50 PM by kevinkr

I acquired a TD-124MKII back in late September and after some months feel like I have come to some understanding of its strengths and weaknesses.

I finally understand that the drive train will never be silent, and needs some periodic maintenance to perform quietly.

Belts are problematic on the MKII, and later versions of the MKI with the dual in chassis intermediate pulley. For some reason very early units seem quieter in this respect.

Motor rebuilding is pretty worthwhile, mine of course was not running so it was mandatory. My experience with motor bearings is limited, but based on replacing a number of bearing sets I would recommend the bearings available from The Analog Depot over others I've tried. They are very precisely made and run well from the get go.

I've added a Bren1 record weight which I feel clamps the record more effectively to the table's moving mass, and I thought improved some areas of performance significantly. Bass...
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Projects, Projects, Projects..

Posted 16th April 2010 at 05:07 PM by kevinkr
Updated 16th April 2010 at 05:19 PM by kevinkr

Like most of us here I seem to have more projects than I can handle. Just added another one - I'm going to do a simple little 6BQ5/6V6/7C5 based SE amplifier for nostalgia. (My first tube amp as a teenager was a 6BQ5 SE)

I've just added to the stack by ordering a pair of 6V6/6BQ5 SE OPTs from Tony over at Twin Audio. The price with shipping was pretty hard to beat, and I figure that the effort they put into building their amplifiers probably is also reflected in the quality of the parts they use. This amplifier will be pretty simple, most likely using pentode mode with some cathode feedback, a single stage high mu triode driver, and some limited global feedback to get the output impedance down. Hopefully I can make enough power to drive the HCC with it. I could conceivably incorporate the baffle step correction into the input of this amplifier if it is dedicated to driving the HCCs. As a firm believer in the benefits of fixed bias the output stage will incorporate that....
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Project Dilemas

Posted 19th February 2010 at 04:41 PM by kevinkr
Updated 19th February 2010 at 04:50 PM by kevinkr

Isn't it odd how sometimes the things you intend to do first end up being the last things you actually get done? Or am I the only one with this problem??

I always have a few projects on the back burner, and few that are supposed to high priority and sometimes one or two that just appear because of an unforseen opportunity or a seemingly good idea.

In order of supposed priority I have been working on a new GM70 based SE amp design, an acrylic plinth TT, a pair of Half Chili Changs, and quite unexpectedly an FFT based audio measurement set up.

The turntable and the GM70 are more or less stalled. I need to purchase a mini-lathe, and a good metal cutting blade.

On the GM70 despite designing a choke coupled driver stage that really performs well I am still waffling over whether I want to use IT coupling instead. And the kicker is I need the above tools to fabricate the chassis for these amplifiers which ultimately will be 4 chassis...
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More iPods N' Things

Posted 3rd December 2009 at 12:22 AM by kevinkr

Well those PX100 headphones came a couple of weeks ago, have to say acoustic sounds was quick on the shipping..

To say they are an upgrade over my old JVC folding phones would be just a bit of an understatement. They're just clearly better in every not so subtle way. Much more extension at both extremes, and much improved clarity - a surprising amount of resolution IMHO for $69..
They're not circum-aural, and have open backs, but surprisingly ambient noise does not seem to be much of an issue. And they're reasonably comfortable.

On a slightly different note I have a fairly large number of songs on my iPod that I downloaded from iTunes. Recently I swapped a not so well liked Pixies album for BT Emotional Technology on Swaptree. I have listened to it a few times and realized that the songs I actually like best are none of the ones I purchased on iTunes! I ripped it to the iPod last night using Apple Lossless and removed the original AAC encoded copies....
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iPods 'n Things

Posted 14th November 2009 at 11:23 PM by kevinkr
Updated 14th November 2009 at 11:28 PM by kevinkr

Went to the gym this afternoon with my iPod (Classic 160GB) as usual - about 15 minutes into a torturous session on the elliptical the left channel just died. PANIC.. I had a further 45 minutes of time to reflect on the meaning of music in my life - in this case it really helps me to get through what I find to be an exceedingly tedious activity. Sonic wall paper to my life outside of my house??

Got home and quickly checked with another set of headphones and determined that my iPod was just fine.The aftermarket JVC folding headphones I purchased a couple of years ago just before this iPod apparently have an open connection somewhere. They never entirely pleased me so I am not too sad to see them go.

Have ordered a set of the folding PX100 made by Sennheiser to replace them - should be a lot better sounding than the failed JVC headphones.

It does rather make me realize just how important a role music plays in my daily life.

As an aside...
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Phono Stage Shoot Out and Conclusions

Posted 14th November 2009 at 05:26 PM by kevinkr

For some time I've had the feeling that there was something not quite right about the sound I was getting out of my most recent phono stage. The phono stage in question had never been compared to anything else, so it was difficult to understand what was going on. To add to the complications I use a Grado Reference Platinum cartridge that has a reputation for being rather laid back - so I was not really sure if the often boring sound was due to the cartridge or a problem with my phono stage design.

The design is a two stage with Lipshitz based passive eq., high transconductance type tubes, and gyrator loads. The tube complement is triode connected D3A in the front end, fixed biased 5842 output stage and gyrator loads based on the 5687.

The problem seemed to center around my choice of cathode bias in the first stage with the D3A. This resulted in a 60 ohm resistor and a 1000uF electrolytic cap shunted by a variety of other caps, after a long succession of problems...
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