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I love my Harman Kardon Rabco ST-8, But....

kmp14

kmp14

Active Member
I really like the HK Rabcos. I think they are a really clever mechnical design. I like how the travel of the tonearm carriage is directly linked to the rotation of the platter, so they are alway in sync. Really smart. Here comes the but....After years of using my ST-8 on my secondary system in my office, I decided to promote it to my main listening system and see how it performed. Unfortunately, I am hearing a lot of mechanical noise when I crank the volume up.

I guess it could be the metal roller in the tonearm carriage running along the rotating bar, or maybe the sound of the bar itself rolling? The platter spins nice an free so I don't think it is the platter bearing.

Any fans of the HK Rabcos run across this? Is it inherit in the design, or something I can work on?
 
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Does this function anything like the Rabco ST-4? I had one back in the 1970s. The little nylon wheels on the arm that rolled on the rotating shaft developed flat spots, which not only caused thumps in the music, but would actually cause the cartridge to nod back and forth a bit.
 
I have an ST-5 that has that same setup with the metal roller. You have to remember that turntable is in a metal box that can resonate sounds. Not the best setup and was one of the complaints about the table. I don't notice any mechanical noise on mine but I'm old and my hearing probably isn't the best. Too much loud music in the 60's and 70's.
 
Calypte said:
Does this function anything like the Rabco ST-4? I had one back in the 1970s. The little nylon wheels on the arm that rolled on the rotating shaft developed flat spots, which not only caused thumps in the music, but would actually cause the cartridge to nod back and forth a bit.
Click to expand...

No, the ST-8 has a metal wheel that rides the rotating shaft.
 
Check the Arm connection to the carriage. If the bushings are dirty or worn you will lose the isolation of the arm from the mechanicals. IIRC
Regards,
Jim
 
Your dilemma is similar to what I experienced and was another reason to move on to a T-60. The case and base of the ST-x series is very resonant. I tried using isolation feet and a different mat to little effect. It is a wonderfully simple and effective design that overlooked the small detail of mechanical noise getting to the cartridge.
 
As someone who owns a total of three of the Harman Kardon/Rabco's (2) ST-7 models and (1) ST-8. IMO my ST-7's are slightly lower in the mechanical noise but not by much. The tables have been cleaned, aligned and tweaked (a lot of fine tuning/adjusting to optimize smoothness). All of my tables have had the interior top and sides lined with dampening material ( a Roofing asphalt product, it's not Dyanmat but gave me the same results...No ringing, it's nearly the same idea for alot less money).

I had been using my ST-8 as my daily driver and out of the blue the table dropped a channel. I have (7) wands with high compliance cartridges and I swapped out one for another and still had the dropped channel. When I get some time I will be opening it up and likely have to replace the tables internal arm wiring to the phono block. So for the time being I have one of my ST-7's back in daily use. This one is a unique table in that its been back to the Harman factory and had the "Factory Upgrade/Repair" made so that it has most of the ST-8 features. This one has the original O-ring roller wheel that I put the latest trend "Flat tire" on the hub and is working very well.

For anyone not knowing about the Factory Upgrade/Repair Harman offered back 80's, this took the ST-7 and basically created an ST-8's features.
1) Upper Rail Assembly being driven with a third belt. The Lower Main Roller has a machined groove on the right side for a small O-ring band to run the upper rail that also had a small drive hub pressed on the right side.

2) The Upper Rail Cover has a small bubble level.

I modded this table with upgraded leveling feet found from a seller on Ebay. These were actually from some better Kenwood table. Don't recall which but they a large thread and nut so no mods to install on the table. I put in LED lamps for the front panel with resistors, and the end of record pick up. Oh and the upper right rail I put in a roller bearing. What's also unique about this table is it's an International model (universal voltage). I've changed out the power cable and RCA cables too.
 
rread13 said:
As someone who owns a total of three of the Harman Kardon/Rabco's (2) ST-7 models and (1) ST-8. IMO my ST-7's are slightly lower in the mechanical noise but not by much. The tables have been cleaned, aligned and tweaked (a lot of fine tuning/adjusting to optimize smoothness). All of my tables have had the interior top and sides lined with dampening material ( a Roofing asphalt product, it's not Dyanmat but gave me the same results...No ringing, it's nearly the same idea for alot less money).
Click to expand...

Jumping back to this thread from several months ago. I "dynamatted" the internals of my ST-8, including the top, internal sides, and the the separator piece that is inside the table.

The arm/carriage seem to be operating properly. I am not sure how I could check clean the bushings that connect the arm assembly to the carriage, but it seems to be fine.

Anyway, after the dynamatting, I am still not happy with the level of mechanical noise. It would seem that the noise would be expected since that metal wheel rides the roller, and the carriage also ride on the spinning bar at the top, all of which would be expected to introduce some noise, right?

All that being said, I would like to at least know that the amount of noise I am hearing is expected. At lower volumes the noise is not really an issue, but "lower volumes"? WHY would we do that? :)

So Rick and all, when you crank up the volume when using your ST-8, what are you experiencing as far as mech. noise? I love the way my ST-8 works and sounds, and want it to be my daily driver, but my Marantz 6300 is quieter so I am torn! Maybe if I know that this is just how the ST-8 is, mech noise wise, I would be more comfortable with accepting it. I am a mess :confused: Such Problems!
 
kmp14 said:
Jumping back to this thread from several months ago. I "dynamatted" the internals of my ST-8, including the top, internal sides, and the the separator piece that is inside the table.

The arm/carriage seem to be operating properly. I am not sure how I could check clean the bushings that connect the arm assembly to the carriage, but it seems to be fine.

Anyway, after the dynamatting, I am still not happy with the level of mechanical noise. It would seem that the noise would be expected since that metal wheel rides the roller, and the carriage also ride on the spinning bar at the top, all of which would be expected to introduce some noise, right?

All that being said, I would like to at least know that the amount of noise I am hearing is expected. At lower volumes the noise is not really an issue, but "lower volumes"? WHY would we do that? :)

So Rick and all, when you crank up the volume when using your ST-8, what are you experiencing as far as mech. noise? I love the way my ST-8 works and sounds, and want it to be my daily driver, but my Marantz 6300 is quieter so I am torn! Maybe if I know that this is just how the ST-8 is, mech noise wise, I would be more comfortable with accepting it. I am a mess :confused: Such Problems!
Click to expand...


KMP14,

I can't jump in for an audible comparison at this time. My living situation has changed and my life's possessions are in a 10 x 10 storage unit. From memory alone I remember the ST-8 having ever so slightly some very low level audible rumble as you have perceived as well. My system had a pair of NHT Sub2 subwoofers that really extended the frequency response down to near or below 20Hz. It took a very keen ear to perceive anything if at all present. I know I never heard any amplified noise getting in the signal path that became discernable or objectionable at any volume; and I liked to run the system at high levels as much as I could. I had used my ST-8 with my Empire 2000Z cartridge and matching correct Empire stylus and had tremendous musical reproduction/enjoyment with my tables. I have a ST-7 that is a factory modified table with the ST-8 like upgrades performed to it BUT mine still had the stock ST-7 Roller that I put a FLAT O-Ring on as a last tweek. I still hold my ST-7 tables above the ST-8 for overall sonic performance, being that my ST-7's have been so finely messaged the mechanisms are silent, smooth as ice after a Zamboni runs over after cleaning the ice! I miss my system, my stuff is in air conditioned storage in Florida.
 
The arm mech is ingenious but the player itself is an undamped resonance festival. I've owned two ST-7, one as an early adopter.
 
rread13 said:
KMP14,

I can't jump in for an audible comparison at this time. My living situation has changed and my life's possessions are in a 10 x 10 storage unit. .
Click to expand...

So sorry to hear that your children (i.e turntables :)) are locked away in storage right now. Thanks for the input on my issues.

Here is where I landed on the subject. I decided to go ahead and put my ST-8 into official service in my main listening location. I think that all of the dynamat I installed has really helped with the resonance issues. I'm really going to try to stop being obsessive compulsive and just enjoy. The noise, so far, has been less noticeable.

I am very sensitive to inner groove distortion, and of course with a linear tracker this is not an issue. Furthermore, I am just so enamored with this unique and funky design so I'm just going to stick with it!

HK ST-8 and McIntosh MA8900

HK ST-8 and McIntosh MA8900

  • Media owner kmp14
  • Date added
 
KMP14,

Looks very attractive in the setup! What's the history of your ST-8? Bought new back in the day or sometime over the last couple of decades/years? I am curious if your's came stock with the clear dust cover or you had one made or it came from an ST-7?

I had bought through Ebay auctions each of my tables over the last 10 years or so. I have had a few ST-7's that I sold but kept (2) ST-7's and the ST-8. My ST-8 came with a clear dust cover and one of my ST-7's came to me with a "smoke" dust cover, of course I had to polish each of them but the "smoke" dust cover belongs with the ST-8 if I'm not mistaken? They look right for each other, and most of the members who posted pictures had the smoke covers with ST-8's. My dampening internally made a substantial improvement to the clarity and depth of my tables sounding so inviting and wanting to just spin records all weekend, it was just a joy to do! I've accumulated (9) wands/arms and each has a highly regarded "heyday/vintage" cartridge, and a arsenal of styli for each!
 
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rread13 said:
9KMP14,

Looks very attractive in the setup! What's the history of your ST-8? Bought new back in the day or sometime over the last couple of decades/years? I am curious if your's came stock with the clear dust cover or you had one made or it came from an ST-7?
Click to expand...

Rick,

I am so glad you asked about the history of my ST-8. I actually bought mine from the original mechanical engineer on the ST Rabcos, Frank Holetsky, back in 2015. On the back of my ST-8 there is a label that lists the engineers, and sure enough he is on there. I also have 2 ST-7s and don't see the label on those. Not sure exactly why, but I have an odd sense of pride that I own one directly from Frank. I guess it is, in a small way, like buying a Les Paul guitar directly from Les Paul...maybe a stretch, but just a bit like that.

I tried to track Frank down a couple months ago to ask him the very questions in this thread, and also to tell him how much I am enjoying my ST-8. Unfortunately I was unable to find him. I am pretty sure he passed away back in December of 2015. I found an obit from back then under his name, in New York, where I am pretty sure he lived. RIP Frank.

Yes, the clear dust cover is from an ST-7. My ST-8 came with the smoke one, but I prefer the clear, so the smoke is on one of my ST-7s in the basement.

I also have a few extra wands (that Frank threw in), but I pretty much stick with the Audio Technica AT150MLX on the ST-8, and don't swap. The AT150MLX really sings on this table! The other reason is that I find it difficult to set the azimuth of the cartridge when the wand comes off and goes back on. My eyes start to go cross when trying to dial that in. There is a surprisingly large amount of range in that azimuth. Any tips for setting that?

What is your favorite cart to run on your ST-8?

Ken
 
KMP14,


kmp14 said:
On the back of my ST-8 there is a label that lists the engineers, and sure enough he is on there.
Click to expand...

My tables as well have labels on the base/bottom plate. That's been a norm on all of the ST-Rabco tables.

kmp14 said:
The other reason is that I find it difficult to set the azimuth of the cartridge when the wand comes off and goes back on. My eyes start to go cross when trying to dial that in. There is a surprisingly large amount of range in that azimuth. Any tips for setting that?
Click to expand...

Do you have one of the Cartridge Alignment Tools; Original or one of the LesE Shapeways recreations? The tool really makes things easier. I set the azimuth by eye looking for level and do have some very small bubble levels that are light weight and can sit on the cartridge and visibly check the bubble.

kmp14 said:
What is your favorite cart to run on your ST-8?
Click to expand...

Favorite cartridges for ST-7 & ST-8: Mounted on wands.
1) Empire 2000Z and Clone 2008
2) Stanton 881S
3) Stanton 681EEE/S
4) Sonus Gold/Blue
5) Shure V15-IV
6) Audio Technica AT15XE
7) Empire 2000E/III
8) Empire 4000D/I

Honorable mentions: Not mounted on wands at this time.
1) Ortofon OM-10
2) Technics EPC-25U
 
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