Just Modded my HK T55C table to Van Alstine's Outboard PS Mod and...

Jazz-Vinyl · « **on:** 22 Dec 2007, 04:27 am »

Oh Oh, Gang!

Just Modded my Harman Kardon T55C with the Outboard Power supply specified by Frank Van Alstine back in 1985...

And...OMG!!

Table now has no AC inside, clean DC only is coming in and it has really transformed this table. Blacknuss is a good thing!

From the first lead in groove - I knew it was a better table.

The image has exploded. Better sonics all throughout the range - but
most noticable on the highest and lowest notes. An upright bass
sounds WAY different (much deeper, much more powerful).

The soundstage is far deeper, taller and wider than before.

I don't say this often, but I do believe the difference is a JAW
DROPPING EXPIRENCE!! I don't think I would have _believed it_ if it
had not happened in my living room!!

Running an Audio Technica 216E Cartridge, it has one of those .2 x.7 mil diamonds (instead of the usual .3 x.7) and whoa...

Micro Detail City!!!!

Micro details, a MUCH larger soundstage and I am a HAPPY CAMPER!

Thank you Frank Van Alstine!! Thank You Wayne (WGH) for showing me the way!!

All my albums are brand new again! All these years with all these micro details hidden from my ears!!!

If you have a table that runs a DC motor...this mod is for you!!

Frank was right when he said "You'll wonder why HK didn't do it this way to start with"....

I was playing Abercrombie's LP: "Gateway" side 2 - Jack Dejohnette gets to tapping on some bells....I had always HEARD them...now I can also 'SEE' them, and tell what shape they are!!

Really an alarming transformation for the BETTER!!

Thanks again, Frank and Wayne...what a Christmas present!

WGH · « **Reply #1 on:** 22 Dec 2007, 05:07 am »

Jazz-Vinyl is not over reacting, the improvements made with this mod is not subtle at all, I've stopped looking at Audiogon turntable ads it's that good.

The power supply is very simple, the transformer and diode bridge is re-used from the turntable. The rest of the parts cost less than $30.
Here is an drawing by Frank's daughter

Wayne

Jazz-Vinyl · « **Reply #2 on:** 26 Dec 2007, 05:00 pm »

Here is a picture of my finished OutBoard Power Supply:

Components are held in via Elmers' Glue. I am going to rig Outboard Supplies for (2) Harman Kardon T25 Turntables. I think I will forgo the AC switch and the fuse. Just plug them into the switched outlet on the Amp or Pre-Amp, so that they are 'only on' when actually being used.

Here are some Mouser Part Numbers for others interested in this mod:

Mouser Parts List:
===================================
140-XRL16V10000 - RC 10,000uF 16V Electrolitic Cap

871-B32633A2103J10 - Metallized Polyester Film Box Capacitor 0.01uF, 2000V, 5% Crimped Leads

539-150104ZZK100AA - DC Film Capacitors 100V .1uF 10%

563-CU-3283 - Bud Plastic Box 6.1X4.6X2.2

16PJ035 - Phono Jack

836-1174 - AC Cord Strain Relief plug

534-818 - 4 Conductor Terminal Strip
===================================

I Suggest you buy the shielded phono cable, 125V Neon Lamp, AC switch, fuse, and fuse holder locally, at Radio Shack.

Cheers!!

WGH · « **Reply #3 on:** 26 Dec 2007, 05:28 pm »

Have you found a difference while listening with the Quartz Lock on or off?
On my table imaging is more stable with QL off.

Wayne

Jazz-Vinyl · « **Reply #4 on:** 26 Dec 2007, 06:02 pm »

Hello Wayne...

Yessir! I do hear the difference! And, it seems to be localized in the upper mids. QL on, and I immediately hear the soundtage of the upper mids recess.

QL off and they come back to full life!

WILD!

And, as you know, the PS mod also beefs up the DC Capacitence to greatly minimize the ripple in the DC Output voltage....so, with the PS mod, the table is ultra ultra steady without the need of the Quartz Lock.

TheChairGuy · « **Reply #5 on:** 26 Dec 2007, 06:19 pm »

That's a very interesting comment about the table sounding better without quartz lock.

Jeff Torgay of TONE Audio recently tested a Technics SL-1200 and a much cheaper direct drive from Audio-Technica. His and others there all felt the AT was superior to the Technics. The AT doesn't have quartz locking, the Technics (famously) does...and has been cited by some as having some upper mid-uneasiness.

Perhaps quartz lock is good for DJ's, but bad for audiophools? Could be.....

Nice job on the outboard transformer, Jazz-Vinyl

John

WGH · « **Reply #6 on:** 26 Dec 2007, 06:59 pm »

John,

I noticed the Harmon Kardon sounded better with quartz lock off even before the ps mod, the micro-adjustments QL makes really screws up the imaging.

Piano notes have less wavering using the outboard power supply, the extra capacitance helps. Removing the A/C transformer made the sound smoother, I guess what people mean by a blacker background.

The H/K turntables are not made as heavy and non-resonant as the Technics, so removing the 1200's transformer may not make as much as a dramatic change, but I was wondering if the reason the Technics sound better by stuffing the inside with PlastiClay is not because you are damping external resonances but instead you are damping the micro-resonances of the internal A/C transformer.

Wayne

TheChairGuy · « **Reply #7 on:** 26 Dec 2007, 07:07 pm »

Quote from: WGH on 26 Dec 2007, 06:59 pm

The H/K turntables are not made as heavy and non-resonant as the Technics, so removing the 1200's transformer may not make as much as a dramatic change, but I was wondering if the reason the Technics sound better by stuffing the inside with PlastiClay is not because you are damping external resonances but instead you are damping the micro-resonances of the internal A/C transformer.

Wayne

Wayne,

That sure could be the case with the Plast-i-Clay mounds. KAB has an outboard power supply option for the Technics that removes the transformer. I think he actually recommends this before any damping trough upgrade. Alas, it's $250.00 (not $30

)

The Technics 1200 doesn't allow you to defect the Quartz Lock...my JVC does, tho. I don't think I ever tested it with and without the quartz lock employed (it was always employed)

John

WGH · « **Reply #8 on:** 26 Dec 2007, 09:26 pm »

Quote from: TheChairGuy on 26 Dec 2007, 07:07 pm

KAB has an outboard power supply option for the Technics.... Alas, it's $250.00 (not $30 )

John

Well that sounds about right, parts $30 x 4 = $120 + retail markup $120 = $240.
Time for a little reverse engineering? Maybe lcrim could take a look inside his unit, it could be as bog simple as the AVA design.

Jazz-Vinyl · « **Reply #9 on:** 26 Dec 2007, 11:47 pm »

Well, I think WGH is on to something when he says the Plast-i-clay in the Audio Technica table may be hiding (absorbing) some of the 60hz hum from the AC transformer being attached to the underside of the table.

Wish I had a real stethoscope, that is what you need to really hear what the tonearm is 'hearing' on any deck.

I have a Technics SL-Q2, said to have very similar specs to the 1200 series of Technics tables, and while it's a heavy, well built and well damped machine, definitely some kind of low freq rumble can be heard on a nice clean lead in groove that is just plain gone-a-roo on the Modded HK. As for the the Soundstage, and highest/lowest notes, the modded HK easily beats the SL-Q2.

I think the HK's could also benefit from a good plast-i-clay stuffing as the only sound heard in the HK deck after the mod is the gentle whir of the DC motor. Plasti-i-clay would probably help dampen that, and we could get some more improvement!

I have some Plast-i-clay on order...

So much fun!!

TheChairGuy · « **Reply #10 on:** 27 Dec 2007, 12:11 am »

TONE AUDIO compared only the stock Technics 1200 and AT decks...no Plast-i-Clay was applied in either.

The Technics is pretty shallow and it's a tri-ply fitting...so there is very little room for Plast-i-Clay in there. Don't know about the SL-Q2

I've clay'ed 3 tables now(all JVC's)....a belt drive unit back in the 80's, and two DD units (both of which had quartz lock) including a current table I have (it's now 33 lbs in total, and almost as feedback resistant as the stock SL-1200)

Jazz-Vinyl · « **Reply #11 on:** 27 Dec 2007, 01:03 am »

Plast-i-clay'ing the JVC's were worth the effort then, eh?

TheChairGuy · « **Reply #12 on:** 27 Dec 2007, 01:12 am »

Quote from: Jazz-Vinyl on 27 Dec 2007, 01:03 am

Plast-i-clay'ing the JVC's were worth the effort then, eh?

Extraordinarily so.....on the first two, I even clayed the top (plinth), and ugliness notwithstanding, it was of great benefit. On many Japanese decks, especially the semi or fully auto variety, there isn't much to damp on the plinth on the underside. So damping the top on these two semi-auto's was very beneficial.

This last one I'm keeping around so I didn't clay the top - and it probably could benefit from it. The Technics 1200 plinth is a lot more inert to begin with so I was pleased upon first inspection of it.

Happy clay'ing...

John

lcrim · « **Reply #13 on:** 27 Dec 2007, 04:05 pm »

KAB outboard PS

The controls on the TT continue to work when this PS is used. And I have a question- What do you suppose is happening to cause the sound differences you hear when the QLL circuit is removed?

WGH · « **Reply #14 on:** 27 Dec 2007, 06:23 pm »

Quote from: lcrim on 27 Dec 2007, 04:05 pm

And I have a question- What do you suppose is happening to cause the sound differences you hear when the QLL circuit is removed?

I dunno, seems counter-intuitive. Perhaps the QLL implementation on the H/K turntables was not a perfect design. The DC motor used is such a tiny little thing, not much mass to smooth out any cogging.

I bought my table in '85, long before the internet was going strong, and discovered this tweak on my own. I have since discovered another user reaching this same conclusion on AA:

Another tip: try running the table with the quartz lock feature turned off. I had all kinds of flutter problems until I figured this out. Apparently, quartz-locking a motor works a lot like a DD turntable where the motor is constantly compensating for load and adjusting itself. Maybe that works on finely engineered machinery, but on a $200 table it seems like the constant adjustments cause more problems than they solve.

Wayne

Wayner · « **Reply #15 on:** 27 Dec 2007, 06:39 pm »

Just a note on the Audio Technica turntable......I think they have an agreement with Technics as almost all of the parts, plinth, platter, base and tonearm look identical to the SL-1200MK2. Even button size and arrangment is almost identical. The Audio Technica sells for $299 at Needle Doctor.

Wayner

Listens2tubes · « **Reply #16 on:** 29 Dec 2007, 02:42 pm »

DIY $30.00

KAB $250.00

Seems reasonable to me.

TheChairGuy · « **Reply #17 on:** 29 Dec 2007, 02:48 pm »

Quote from: Wayner on 27 Dec 2007, 06:39 pm

Just a note on the Audio Technica turntable......I think they have an agreement with Technics as almost all of the parts, plinth, platter, base and tonearm look identical to the SL-1200MK2. Even button size and arrangment is almost identical. The Audio Technica sells for $299 at Needle Doctor.

Wayner

It's probably no agreement between them...it's simply reverse engineering by an enterprising Chinese company.

Matsushita patents on everything turntable-related have likely long expired now...no budget is likely allocated by the big Japanese companies for turntables anymore

John

Wayner · « **Reply #18 on:** 29 Dec 2007, 03:00 pm »

Audio Technica is Japanese, and though they may be built in China, I would think there are still copyright laws in Japan safeguarding design. I wonder if AT isn't even a division of Matsushita.........I don't have a clue. Perhaps your right, John.

W

Jazz-Vinyl · « **Reply #19 on:** 29 Dec 2007, 03:05 pm »

To 'Listens2tubes' -

I guess your saying the DIY looks like crap? LOL...

Well, that is okay, because once the lid is on, you don't see the innards and you SURE won't care because you'll be so busy enjoying what's happening at the stylus end of the T55C tonearm.

Someone earlier said that the KAB outbard power supply enabled everything (all the features of the table) 'to still work'. The DIY T55C mod is the same. All features of the table still work, you are just removing AC and the associated AC HUM from inside the deck.