Plitron 1000VA Transformer Evaluation

DarqueKnight
DarqueKnight Posts: 6,664
edited April 2012 in Vintage Speakers
Introduction

In my evaluation of the discontinued Avel Lindberg AV-047548 1000VA isolation transformer, I suggested one of Plitron's 1000VA shielded medical isolation transformers, model number 6166, as a substitute. Forum member thsmith purchased a Plitron 6166 and sent it to me for evaluation against the AL AV-047548. This transformer was evaluated for use in a custom AI-1 non-common ground amplifier interface.

In summary, the sound quality of the Plitron was between that of the A-L 800VA Y236906 and the A-L 1000VA AV-047528. The 1000VA A-L provided a wider and deeper sound stage, more image weight and more overall clarity and detail, particularly in the bass. The A-L is larger and has better build quality than the Plitron.

PlitronShieldOn-s.jpg
Figure 1. Plitron model number 6166-X0-00 1000VA medical isolation transformer.

PlitronShieldOff-s.jpg
Figure 2. The Plitron transformer's metal shield is much thinner than the Avel Lindberg's and is not
permanently attached like the Avel Lindberg's.


Plitron-AL-1000VA-s.jpg
Figure 3. The A-L transformer is 23% larger, 16% heavier and has better construction quality than the
Plitron.


Burn In And Listening Evaluation

Similar to the AL 1000VA transformer, the Plitron displayed awful overall veiling, grainy midrange and highs and smeared bass. The sound stage was reduced two feet at the sides and front. Clarity and detail significantly improved after 24 hours of music play, but the sound stage constriction and lack of bass detail and articulation remained. Twenty-one hours of conditioning on the Audiodharma Cable Cooker removed the last of the bass smearing, but the bass was still not as articulate and detailed as with the AL transformer. The reduction in sound stage width and depth still remained.

Going back and forth between the Plitron and the Avel Lindberg transformers, the following differences were noted when the Plitron was in service:

1. Less of a sense of layering and front to back space between images.
2. Bass slam was gone completely.
3. Clean, articulate micro growls from electric and acoustic bass instruments were diminished.
4. Finger snaps were not as crisp and sharply defined.
5. Diminished airiness of high frequencies.
6. Less image weight.
7. Images at the sides of the sound stage moved inward two feet.
8. Images forward of the speaker plane moved back two feet.

DN-Pli-Tuner-corr-s.jpg
Figure 4. Initial burn in and listening evaluation setup. The tuner on the floor at the right was used to play
music overnight.


Plit-Cab-Ckr-s.jpg
Figure 5. The Plitron transformer was burned in for 21 hours on the Audiodharma Cable Cooker.

DN-Plit-Vertical-s.jpg
Figure 6. Both the Avel Lindberg and Plitron transformers sounded better when oriented vertically.

My AI-1 Dreadnought sits on its left side behind the right speaker. I would prefer it to rest on its feet, but there is not enough space between the speaker and the wall. When I brought the Dreadnought out front for comparative listening with the Plitron transformer, it was sat horizontally on its feet. There was a small lack of clarity and detail. Setting the Dreadnought on its side restored the sound to its prior quality. Up to then, I had not considered that orientation might affect the transformer's sound performance

Measurements
Table 1. Plitron 6166 Measured Specifications
6166MeasuredSpecs-s.jpg

Table 2. Avel Lindberg AV-047548 Measured Specifications
ALAV047548MeasuredSpecs-s.jpg

AL-Plitron1000VAFR-Notes-s.jpg
Figure 7. The measured room responses of the Plitron and AL transformers were nearly identical.

The following six figures show Fast Fourier Transform noise spectrum measurements of test signals at 100 Hz, 1 kHz and 10 kHz. It may be easier to see differences in the plots if they are saved to your computer and viewed in succession. At 100 Hz the Plitron had significant odd order harmonics (3rd, 5th, 7th). With the Avel Lindberg the second harmonic was dominant and harmonics after the third were suppressed (figures 8 and 9).

At 1 kHz, the Plitron's third harmonic was dominant and was accompanied by a slightly smaller second harmonic. The Avel Lindberg's harmonics were entirely suppressed at this frequency (figures 10 and 11).

At 10 kHz, the Plitron displayed less overall noise density and a slightly higher (by 1 dB) third harmonic (figures 12 and 13). The harmonic content shown in the FFT plots agrees with the harmonic distortion measurements taken with Dayton Audio's Omni Mic system (figures 14 and 15).

2Plitron100HzShielded-s.jpg
Figure 8. FFT plot of Plitron transformer with 100 Hz test signal.

ALT2100HzFFT-s.jpg
Figure 9. FFT plot of Avel Lindberg transformer with 100 Hz test signal.

2Plitron1kHzShielded-s.jpg
Figure 10. FFT plot of Plitron transformer with 1 kHz test signal.

ALT21kHzFFT-s.jpg
Figure 11. FFT plot of Avel Lindberg transformer with 1 kHz test signal.

2Plitron10kHzShielded-s.jpg
Figure 12. FFT plot of Plitron transformer with 10 kHz test signal.

ALT210kHzFFT-s.jpg
Figure 13. FFT plot of Avel Lindberg transformer with 10 kHz test signal.

The color coded lines in the harmonic distortion plots represent the following:

Black - frequency response.
Dark blue - sum of 2nd-5th harmonics.
Red - 2nd harmonic.
Purple - 3rd harmonic.
Green - 4th harmonic.
Light blue - 5th harmonic.

It is easier to see differences in the harmonic distortion plots if they are saved to your computer and viewed in succession.

PlitronHarmDist5-s.jpg
Figure 14. Harmonic distortion plot of Plitron transformer.

AFTJantzHFInd04mHHarmDist5-s.jpg
Figure 15. Harmonic distortion plot of Avel Lindberg transformer.

The bass decay plots show how long it takes the sound to decay at each frequency. The ideal situation is flat response which means that some bass notes do not last much longer than others. Significant differences in decay times can cause a decrease in bass definition. The overall shape of the bass response is very similar between the Plitron and the Avel Lindberg, but the Plitron has longer decay times.

PlitronBassDecay-s.jpg
Figure 16. Bass decay plot of Plitron transformer.

AFTJantzHFInd04mHBassDecay2-s.jpg
Figure 17. Bass decay plot of Avel Lindberg transformer.


Reference

The-AI-1-Dreadnought-Project-Pt.2-Upgrade-to-1000VA-Transformer
"So hot it burns Mice!"~DK
"Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
"Knowledge, without understanding, is a path to failure."~DK
"Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
Post edited by DarqueKnight on

Comments

  • headrott
    headrott Posts: 5,477
    edited April 2012
    2. Bass slam was gone completely.

    Completely Ray? From everything I have read of your evaluation write ups, I've not known you to write in hyperboles, but completely gone? I have some bass slam even with the 800VA transformer, so I am just trying to figure out if this is somewhat of an exaggeration Ray. This is not an attack on your write up Ray so please don't take it as such. Thank you for the write up and the comparison.

    Greg
    Relayer-Big-O-Poster.jpg
    Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:
    "I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion." :\
    My response is: If you need 60 seconds to respond in one sentence, you probably should't be evaluating Polk speakers.....


    "Green leaves reveal the heart spoken Khatru"- Jon Anderson

    "Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee
  • thsmith
    thsmith Posts: 6,082
    edited April 2012
    Thanks Ray !

    I have the Plitron ready for putting in my system with my common ground Wright Tube amp.

    I need to cut my KK 4TC in half and add banana plugs this weekend.

    I read that the Plitron is better than the AL 800VA but not as good as the 1000VA.

    If that is the case I am fine running the Plitron, would prefer the 1000VA but.....
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs
  • Toolfan66
    Toolfan66 Posts: 15,209
    edited April 2012
    thsmith wrote: »
    Thanks Ray !

    I have the Plitron ready for putting in my system with my common ground Wright Tube amp.

    I need to cut my KK 4TC in half and add banana plugs this weekend.

    I read that the Plitron is better than the AL 800VA but not as good as the 1000VA.

    If that is the case I am fine running the Plitron, would prefer the 1000VA but.....

    Let your ears be the judge..:cheesygrin:
  • DarqueKnight
    DarqueKnight Posts: 6,664
    edited April 2012
    headrott wrote: »
    I have some bass slam even with the 800VA transformer, so I am just trying to figure out if this is somewhat of an exaggeration Ray.

    No exaggeration. The "thunder" disappeared. There was an overall softening of bass with diminished detail and tactile sensation. The Plitron had a better midrange and high frequency presentation than the 800VA AL, but the 800VA AL had better bass and spatial presentation than the Plitron. The 1000VA AL was better in every respect than the 1000VA Plitron.
    thsmith wrote: »
    I have the Plitron ready for putting in my system with my common ground Wright Tube amp.

    I read that the Plitron is better than the AL 800VA but not as good as the 1000VA.

    Let's qualify that and emphasize that these results were on one particular system heard with one set of ears. I don't recall whether you have the AL 800VA. If so, I hope you will share your insights between the two in your system.
    Toolfan66 wrote: »
    Let your ears be the judge..:cheesygrin:

    As always, the best advice.
    "So hot it burns Mice!"~DK
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK
    "Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
  • thsmith
    thsmith Posts: 6,082
    edited April 2012
    No, I have just the Plitron to put in my system.

    I am still on fence about adding it since my new preamp has about 60 hours and is still burning in.

    I have the "-" KK 4TC cable ready to go but need to cut the "PIN" KK 4TC in half in order to integrate the Plitron.
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs
  • headrott
    headrott Posts: 5,477
    edited April 2012
    No exaggeration. The "thunder" disappeared. There was an overall softening of bass with diminished detail and tactile sensation. The Plitron had a better midrange and high frequency presentation than the 800VA AL, but the 800VA AL had better bass and spatial presentation than the Plitron. The 1000VA AL was better in every respect than the 1000VA Plitron.

    Interesting. I guess that may be the difference between an isolation transformer designed for use in audio (AV-047528) and an isolation transformer designed for use in a medical setting (Plitron 6166 ). Thanks Ray.

    Greg
    Relayer-Big-O-Poster.jpg
    Taken from a recent Audioholics reply regarding "Club Polk" and Polk speakers:
    "I'm yet to hear a Polk speaker that merits more than a sentence and 60 seconds discussion." :\
    My response is: If you need 60 seconds to respond in one sentence, you probably should't be evaluating Polk speakers.....


    "Green leaves reveal the heart spoken Khatru"- Jon Anderson

    "Have A Little Faith! And Everything You'll Face, Will Jump From Out Right On Into Place! Yeah! Take A Little Time! And Everything You'll Find, Will Move From Gloom Right On Into Shine!"- Arthur Lee
  • DarqueKnight
    DarqueKnight Posts: 6,664
    edited April 2012
    thsmith wrote: »
    I am still on fence about adding it since my new preamp has about 60 hours and is still burning in.

    I hope you can wait until the preamp is burned in. On the other hand, I know how it is when new toys have arrived.
    "So hot it burns Mice!"~DK
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK
    "Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
  • thsmith
    thsmith Posts: 6,082
    edited April 2012
    I hope you can wait until the preamp is burned in. On the other hand, I know how it is when new toys have arrived.

    I think getting at least 150 hours on the preamp would be good. I have to cut my current IC to use the AI which means there is no going back, unless I do something wonky to temp splice the cable.

    I will give to the weekend to decide.
    Speakers: SDA-1C (most all the goodies)
    Preamp: Joule Electra LA-150 MKII SE
    Amp: Wright WPA 50-50 EAT KT88s
    Analog: Marantz TT-15S1 MBS Glider SL| Wright WPP100C Amperex BB 6er5 and 7316 & WPM-100 SUT
    Digital: Mac mini 2.3GHz dual-core i5 8g RAM 1.5 TB HDD Music Server Amarra (memory play) - USB - W4S DAC 2
    Cables: Mits S3 IC and Spk cables| PS Audio PCs