[Jazz-Vinyl]

More Harman Kardon T25/T55C reporting...

I could not wait any longer for the Plast-i-clay to arrive so I went to the local store, Hobby Lobby, and purchased 3 pounds of the clay (at twice the online price). 

Heated each pound for 1 minute in the microwave and proceeded to pack it into the underside of the T25.  Turned it over and filled (pretty much) the cut out on the top side too (where the guts for the Semi-Auto gearing lives).

It's packed up pretty good, it might hold another 1.5 pounds underneath but certainly no more than an additional 2 pounds.

Tried it out, and it IS amazing the sonic difference it made. 

The Sonics are very very good.  The bass note I complained about previously is now present.  I believe Frank made a comment that this table "went lower" than anything else he had ever owned (his comment was about the T30 - almost identical to the T25).  And I agree, it has a heck of a bottom, not boom mind you, but a bass note that is really solid.

I am also noticing another interesting difference in the T25 compared to the T55C...

The soundstage is a little smaller on the T25.  Not by a really big margin, but it is smaller.  However, I can "locate" instrumets more precisely in the T25's soundstage.  The T55C has a larger soundstage but it's "mushier" - is that a word?

It's really interesting to study the same tracks on the two tables.  I played side two of Billy Cobham's "Spectrum" on which his drum set featured and the presentation is that you are on the drummers throne and his drum kit is all around you.

On the T25's presentation, I can easily feel the location of each tom tom and the position and height of each cymbal.  It's really exact and stays put throught side two.

On the T55C, I get the same location sensations, but it's not as precise.  A tom tom can change positions slightly on the T55C, and does not feel like it stays "locked in" positionally as it does on the T25.

Without a doubt, I will be packing up the T55C's innard's with
plast-i-clay when my 10 pounds (via mail order) arrives. 
Maybe the Plast-i-clay will also tighten up the soundstage locations on the T55C and allow it to retain the somewhat larger (it's a bit deeper, wider and taller) soundstage??

Anyone know the technical reasons why these two tables present themselves so differently?

Physically the differences are:

1> T55C is a suspended "floating" table. T25 is rigid.

2> T55C is MUCH heavier than the T25, even when the T25 is packed up with the clay.

3> The T55C has an 8 gram (ultra light mass) tonearm, the T25 has an 11 gram (low end of medium mass) tonearm.

Both tables enjoy an Outboard Power supply, only 12 Volts of clean DC come into the tables.

Everything was heard through the same two carts: AT 216EP and I found my Shure RXT5 that was in good condition,  tried both carts on both tables.  The two carts have a slightly different sonic signature (the Shure goes deeper, sounds darker and the AT is a bit more realistic sounding in the high end).

Definitely I am certain of my report regarding soundstage and precise locationing.

Cheers!!!

[TheChairGuy]

J-V,

I've clayed a few tables...when I first look at 'em I figure the most they'll need is a few lbs.  Then, as I get working a bit on them, my estimate raises to about 5 lbs (like you now).  Then, once I've pounded the 5 lbs in there...I invariably find ways to shove another 3-5 lbs. in there (and on the platter underside if there is clearance) 

At least on the 3 Japanese (all semi or fully auto, too) tables I've done this on, I've pounded each with 8-10 lbs total in there.  I don't know how much room HK gives yo in there, but you might find you need more.

The cheapest online source I've found is AllArtSupplies...they are very cheap, like almost a third of what Michael's charges for modelling clay.

I don't have any answers to your questions - but turntable-ism is all about minor differences in mechanics making rather large-ish differences in sonics.  I find spring suspended/belt drive decks have the largest soundstage (but can sound 'mushy', or otherwise describes as 'plush')....the mass-laden/non-suspended have tighter bass and smaller soundstages.

I think that is what you are describing...this is what I have found exactly, as well, over time. I defeat springs now when possible as I like the solid, mass-laden tightness over the plushness of sprung designs.

You appreciate both types for what they can do and there is no absolutes, of course

Love your rabid posts, J-V 

John

[Jazz-Vinyl]

Well thanks, ChairGuy for confirming what I was hearing.

I have never had a good Sprung table before, so this was a new discovery for me.

I do seem to prefer the floating suspension/larger image of the T55C for the living room stereo, but, I can see how the "sharper location / deeper bass note" of the T25 will be perfect as the Transcription table to send some of my favorite LP's to MP3 for portable listening purposes.

One last Sonic note, is that the T25 minimizes surface noise better than the T55C.  What can be heard as a pretty loud POP on the T55C, often sounds like a much tamer "Tick" on the T25.  Again, an advantage for a "To MP3" table...

There is one more mod I am going to do to both HK tables....

I want to take the bottom metal piece (with the feet) off and replace it with a 1 inch thick piece of MDF.  Then another piece of 1 inch thick MDF will be used as the "leveling base" - I will attach three "speaker cones" to the bottom of this for easy leveling.  Then, I see at Lowe's they sell a thick sorbathane mat for $9.99, will buy one of those, and cut it to fit between the leveling base and the table.   That should do it for isolation from external vibrations, and enable pinpoint/precise leveling.

This has been a LOT of FUN....

Thanks to all in here who have helped!!

[TheChairGuy]

A thick hunk of wood worked for me.....in fact, it's a more important upgrade than nearly any cartridge swap-out 

http://www.audiocircle.com/index.php?topic=42423.0

1" MDF and some sorbothane probably ain't enough (tho it's definitely on the right path)........if you have an IKEA near you they sell 1-2" birch cutting boards cheap.  2-4 stacked together then under your tables will likely provide it with great isolation 

Regards, John

[Jazz-Vinyl]

Hmmm!!!   This would be 2 slabs of 1" thick MDF...with the sorbothane between.  Don't think that will suffice, 'eh?

[Wayner]

You guys are getting MDF happy. It is made of glue..............

[Jazz-Vinyl]

But it IS very acoustically dead!!!

[Wayner]

I know..I was just kidding. I think it's awesome to listen to vinyl that fades out to black. It can be very becoming. Seek the Holy Grail of vinyl, men. Sometimes the tweak is obvious, sometimes it was the wrong thing, Sometimes the tweak sounded good yesterday, and bad today. Why is that? It must be Psycho-acoustical or some rubbish like that.

You say 2 1" pieces of MDF with sorbothane in between, huh.................................... ......

Wayner  aa

[Jazz-Vinyl]

Yeah, and earlier I voted for preferring the T55C to the T25 after seeing that there is a difference in the soundstage (T55C has the edge) and precision of instrument locationing and....the bottom-est (is that a word?) note (T25 wins here).

But been swappin' 'em out again today, and my goodness, might have to change my vote to preferring the T25!!  GAWD!   What to do!  But what a FUN problem! 

Definitely, the T25 has both the lowest and and the highest notes revealed in the greatest detail...

If you read all through Frank's newletters about these two tables (he cites the T60 and T30) he says the T30 had the better reproduction and also cited that bottom note.  At first I thought he was just saying this because he could no longer obtain the T60's, and only had the T30's for sale...but, it seems that after all, with all his specified tweaks in place....

My wife has cited "phycho-acoustical" and thinks I am a nut case.  When she saw me stuffin the T25 with the Clay, she said "How will you _KNOW_ when you have reached Vinyl Nirvanna"...LOL

I told her "Don't worry, I'll know..."  << GRINS >>

[Wayner]

Next your wife will be limiting how much plasticlay you go through in a week.

I'm thinkin support group!

 

[Jazz-Vinyl]

Shhhhhhhh!!!   We don't want to get anything like that started!!!

I stay in enough trouble with "the hobby"!!

[TheChairGuy]

J-V,

The birch boards at IKEA are nice (depending on size they run $20-25 each).  2 x 1" MDF + sorbothane layer is good, certainly it's painlessly inexpensive.  4 x 1" might be better still 

I always used the white, tan or grey clay...the black clay (from certain makers) has a particular smell that's not pleasant to me.  pee-youuuuu 

John

[dorokusai]

And the clamp...was bought on Ebay from a fellow in Canada.  I don't see him on Ebay anymore.  I paid like $24.00 for it shipped.  It's made of aircraft aluminum and it has rubber o-rings where it fits onto the spindle.  He said they were all custom made on his own CNC lathe.

It looks great, spin on.

Mark

[Jazz-Vinyl]

Happy New Year to all the folks in here!!

Been swappin' and swappin' the T55 and T25, definitely I like the fuller soundstage better of the T55 for the living room and will use the T25 (not a slouch table!) for my "To MP3 transcriptions".

Funny how different they sound on some recordings.  Also found the T25 really EXCELS on good recordings.  But the T55 kind of "evens 'em all out a little" and poopy recordings sound better on the T55 and good recording sound perfectly great.  With very careful VTA on the T55, I can get the surface noise down to ALMOST what it is on the T25.

That danged big honkin' soundstage on Moded the T55 is sooooooooooooo nice, and 100% addictive!!!

Steely Dan's "Countdown To Ecstacy" is an example of the different charactors of these two tables.  Original ABC pressing I bought new in 1973 (I was a "NO FUN" MANIAC at vinyl care...all my LP's bought as a teen and young man play perfectly like new today).  I used to think that this was a FANTASTIC sounding recording.  The T25 revealed it was an "Okay" sounding recording, kind of sterile and bit brittle in some areas.  The T55 made it sound like I remembered it sounding back in the day...real lush with scads of tiny surprises,  like the Vibes, mini-percussions and...other small sonic treats thrown in here and there.

Ever noticed there is an "Extra hand" on the mix board on the back cover photo of that album??!!  Check it out...someone is hiding beneath the board and has his/her left hand on the mix board...

Another cool advantage of Vinyl...that nice artwork!!!

Gotta love it!!! 

Cheers!!!!