SPEC GMP-8000 Measurements

volken

Well-Known Member
Apr 30, 2018
18
10
108
Netherlands
Just finished some W@F measurements on the SPEC-8000 belt driven turntable , done with a Denon 3 KHz test record for speed and W@F , after this a rumble measure with the same record.
Pitty enough I could not use the Thorens messkoppler because the spindle diameter was 7.06mm so I could not fix it on the spindle.

SPEC GMD-8000 ser.0009 Rumble spectrum record.png WP_20180707_14_11_48_Rich (2).jpg
 

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jsn

VIP/Donor
Jan 8, 2014
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Hi volken,
Thanks a lot for the sharing.
I'm sorry that I do not know how to interpret the picture.
The wow & flutter for techdas af1 measured in HFN having the peak wow and flutter # 0.01%/0.02%.
.
For the sake of simplicity, may I know what is the peak wow and flutter # for your measurement of the SPEC GMP-8000 ?
.
Thank you.
Regards, jsn
 

Solypsa

Well-Known Member
Jun 7, 2017
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www.solypsa.com
Will you be doing any subjective listening reports, or is this just an objective measurement exercise?

The Groovemaster tonearm is in elevated company :)
 

spiritofmusic

Well-Known Member
Jun 13, 2013
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Aha, my favourite left field tt option, please leave some impressions on SQ, thanks.
 

volken

Well-Known Member
Apr 30, 2018
18
10
108
Netherlands
Hi volken,
Thanks a lot for the sharing.
I'm sorry that I do not know how to interpret the picture.
The wow & flutter for techdas af1 measured in HFN having the peak wow and flutter # 0.01%/0.02%.
.
For the sake of simplicity, may I know what is the peak wow and flutter # for your measurement of the SPEC GMP-8000 ?
.
Thank you.
Regards, jsn

Yes sorry but I always measure this way because these single figures tell you nothing about were they come from .
Most times there is no mention about what record was used or what kind off filtering or level was used.
Here you can see that the flutter components are very low but speed stability could be better , the peak , recognizable by many belt drive turntables.

Regards Volken
 

volken

Well-Known Member
Apr 30, 2018
18
10
108
Netherlands
Will you be doing any subjective listening reports, or is this just an objective measurement exercise?

The Groovemaster tonearm is in elevated company :)

Just a measurement to see how a modern turntable compares against the old idlerwheel .
This one has a very low flutter components but speed stability could be better .
 

volken

Well-Known Member
Apr 30, 2018
18
10
108
Netherlands
Aha, my favourite left field tt option, please leave some impressions on SQ, thanks.

They have been mistaken in the thickness of the centerpin, which is clearly below par. measured 7.06mm so I could not use my Thorens Messkoppler.
It also causes extra wow when not centered accurately !
At the same time, the speed control too coarse was very difficult to set up because the speed was not stable.
Regards
 

jsn

VIP/Donor
Jan 8, 2014
40
1
398
Yes sorry but I always measure this way because these single figures tell you nothing about were they come from .
Most times there is no mention about what record was used or what kind off filtering or level was used.
Here you can see that the flutter components are very low but speed stability could be better , the peak , recognizable by many belt drive turntables.

Regards Volken
.
Hi Volken,

Yes. I agreed with you that your presentation would give more complete picture for the measurement.
WRT about the speed stability, the tension of the string would affect the performance.
.
SPEC told me that the suitable tension would be found by the initial rise time to nearly constant rotation, around 15 seconds each 33 1/3 rmp and 45 rpm.
.
My experiment would be the least the better so I tune it to just barely enough to start the tt. In my tt, the initial rise time is around 70 sec.

Perhaps you can try different setting of the tension and see speed stability changed.

Thank you.
Regards, Jason.
 

microstrip

VIP/Donor
May 30, 2010
20,806
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Portugal
Just finished some W@F measurements on the SPEC-8000 belt driven turntable , done with a Denon 3 KHz test record for speed and W@F , after this a rumble measure with the same record.
Pitty enough I could not use the Thorens messkoppler because the spindle diameter was 7.06mm so I could not fix it on the spindle.

Good measurements - any "serious" review of a turntable in the late 70's would need such graphs. However, after the Oracle people only considered resonances and decay after tapping the mat!

I must have some paper measurements of old turntables but are now in storage do not have the time to dig inside them. The only thing I found online are the Linn Sondek measurements taken by Stereophile https://www.stereophile.com/content/linn-lp-playing-system-measurements. They can be used for a comparison with your data, although the center frequencies are different.

I have taken a few similar wow and flutter spectra, but of the Studer A80 - much more complex to interpret, as each moving part contributes with a separate line, depending on its diameter. Probably sometime in the future I will take a few measurements of the EMT 927 to study the influence of power supply in this turntable. But now all my interest is just listening!
 

spiritofmusic

Well-Known Member
Jun 13, 2013
14,605
5,413
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E. England
Jason, you own the GMP?
Its a very rare beast, with only one or two examples in Europe, so very hard to go and hear.
Can you elaborate on how it sounds, I'm a sucker for its Old School design aesthetic.
 

volken

Well-Known Member
Apr 30, 2018
18
10
108
Netherlands
Good measurements - any "serious" review of a turntable in the late 70's would need such graphs. However, after the Oracle people only considered resonances and decay after tapping the mat!

I must have some paper measurements of old turntables but are now in storage do not have the time to dig inside them. The only thing I found online are the Linn Sondek measurements taken by Stereophile https://www.stereophile.com/content/linn-lp-playing-system-measurements. They can be used for a comparison with your data, although the center frequencies are different.

I have taken a few similar wow and flutter spectra, but of the Studer A80 - much more complex to interpret, as each moving part contributes with a separate line, depending on its diameter. Probably sometime in the future I will take a few measurements of the EMT 927 to study the influence of power supply in this turntable. But now all my interest is just listening!

I have measured the EMT 927 they are the best speed stability measurements so far , also my own 930 is very good specially with the clean 3 phase power supply I made for it.
Edward M. Long off Audio magazine USA started this kind off measurements in the heyday of the turntables.
Yes I measured also on my Studer B62 the W@F very interessting to show the difference between the pinchrollers .
 

volken

Well-Known Member
Apr 30, 2018
18
10
108
Netherlands
.
Hi Volken,

Yes. I agreed with you that your presentation would give more complete picture for the measurement.
WRT about the speed stability, the tension of the string would affect the performance.
.
SPEC told me that the suitable tension would be found by the initial rise time to nearly constant rotation, around 15 seconds each 33 1/3 rmp and 45 rpm.
.
My experiment would be the least the better so I tune it to just barely enough to start the tt. In my tt, the initial rise time is around 70 sec.

Perhaps you can try different setting of the tension and see speed stability changed.

Thank you.
Regards, Jason.

Jason I found the speed adjustment rather coarse difficult to adjust on the exact speed and it drifted some during testing , tension changed this this some what .
Also the centerpin is below spec. I measured 7.06 mm as a result of which my rumble jig can not be fixed, it also seems to give me problems with some clamps.
Centering is critical for low wow specs this way especially because the centerhole is much too large for many new records.
 

spiritofmusic

Well-Known Member
Jun 13, 2013
14,605
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E. England
Can anyone please tell me how the Spec tt sounds?
I have asked a few times, is this too much to ask?
 

jsn

VIP/Donor
Jan 8, 2014
40
1
398
Can anyone please tell me how the Spec tt sounds?
I have asked a few times, is this too much to ask?

YES. I have the SPEC TT.
I spent a few day to check if there was any sound coming from the SPEC TT.
It is lucky that I did not hear any crunching or rumble noise . It runs very smooth. :)
.
.
Let's share about how I enjoy the music playing through the SPEC TT .
.
The first thing that impressed me is the huge 3d sound stage .
When I play the full scale orchestra music, like the Scheherazade Reiner CSO , the brass instrument group appeared at the back stage over 20 feet.
In the music hall, the decay of the violin would be reflected from the ceiling. Christian Ferras, Bruch Violin and Lao Symphonie espangole , SBLTP 1488 is one of the good example . When I play this record, I could hear that the violin was at a bit left of the centre and the reflection was from the ceiling .
.
The 2nd thing would be the energetic attack and the wonderful decay of the acoustic instrument music.
Anserment conducting OSR to perform the Stravinsky ‘The Fire bird’ act 1 part 2 (SXL 2017 ), the sound from Brass instrument was prompt and vibrant .
The decay of the violin music piece from the Henryk Szeryng 9SFL 14117) is natural and smooth.

I don’t have too many jazz/pop music records but playing the Keith Don’t Go from Nils Lofgren, I’d tap my feet with music.

The flow of music playing through this GMP-8000 is lively , vivid and unbounded.
 

bonzo75

Member Sponsor
Feb 26, 2014
22,443
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Nice selection. I use the scheherazade and the Lalo both. For lalo symphonie espagnole, I have Ricci Decca ED2, Henryk Szeryng classic records and Henryk Szeryng RCA Victor red seal. I prefer the Szeryng more.
 

spiritofmusic

Well-Known Member
Jun 13, 2013
14,605
5,413
1,278
E. England
Jsn, fantastic summary of the Spec's strengths.
I have found since I've moved to an idler/direct rim drive, very few belt drive tts float my boat (an honourable exception being the SOTA Vyger), so it was with great interest I read your words re the "lively, vivid..." sound, these are adjectives I very rarely attribute to belt drives.
 

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