HammondWiki - Diff: ToneWheelGeneratorOutputLevels

@@ -1,7 +1,7 @@

! THEORETICALLY POSSIBLE HAMMOND FACTORY TONEWHEEL GENERATOR OUTPUT LEVELS FOR THE HAMMOND ORGANS OF THE VARIOUS ERAS OF PRODUCTION.

-By ~~KonZissis~~

+By Kon Zissis

I have never seen any Hammond factory chart that shows the official correct factory TG output levels measured directly from the TG terminal strip in millivolts Peak to Peak ( mVpp ) or in millivolts RMS ( mV RMS ) . However there is an Alan Young factory report from 1969 which has some information . Mike Fulk posted this to Hamtech in 1998 and it says the following~:

Report by Alan C Young, Senior Product Analysis Engineer:

@@ -13,9 +13,9 @@

250 Hz is between the TG notes 36 and 37.

3.2 mV RMS is 9.05 millivolts peak to peak ( mVpp ) and 8 mV RMS is 22.62 mVpp. To convert sine wave frequencies in mV RMS into mVpp , you multiply the mV RMS level by 2.828 to get the mVpp level. To convert the complex waveform mV RMS level of the bass pedal TG notes 1 to 12 into mVpp , you multiply the mV RMS level by 4.7. For example ,a sine wave at 3.2 mV RMS multiplied by 2.828 equals 9.05 mVpp and a complex waveform bass pedal note at 14.89 mV RMS multiplied by 4.7 equals 69.83 mVpp

-According to most of the measured TG output curves that l have , Alan Young's quoted 9.05 mVpp seems weaker than the more common 10 to 11 mVpp for the TG note 36 and 22.62 mVpp for the TG note 91 seems too strong compared to the more common 15 to 20 mVpp levels of the measured TG’s in my TG spreadsheet. I do not know how accurately these Alan Young quoted mV levels compared to the actual ~~'' real world~~ factory TG ~~calibration~~ , but l have made up a theoretical output curve by drawing a straight upward line starting with 9.05 mVpp for the TG note 36 and then going all the way up to 22.62 mVpp for the TG note 91 and l have printed out these output levels for the TG notes 36 to 91 further down below.

+According to most of the measured TG output curves that l have , Alan Young's quoted 9.05 mVpp seems weaker than the more common 10 to 11 mVpp for the TG note 36 and 22.62 mVpp for the TG note 91 seems too strong compared to the more common 15 to 20 mVpp levels of the measured TG’s in my TG spreadsheet. I do not know how accurately these Alan Young quoted mV levels compared to the actual Hammond factory TG output curve specs used by the Hammond employees who calibrated the TG's , but l have made up a theoretical output curve by drawing a straight upward line starting with 9.05 mVpp for the TG note 36 and then going all the way up to 22.62 mVpp for the TG note 91 and l have printed out these output levels for the TG notes 36 to 91 further down below.

I have the measured TG output levels of over sixty organs in my amassed collection of TG output levels data in my TG data spreadsheet including pre 1964 TG's with wax capacitors , pre 1964 TG's that have been recapped with new capacitors and post 1964 TG's with red mylar capacitors .

By looking at the all the measured TG data in the TG spreadsheet l can see a definite trend in the TG output levels. Although each TG has slight differences with individual notes sticking out or being weaker than others , there is a definite similar overall pattern with most of the output curves.

@@ -50,10 +50,11 @@

Here below are the actual output levels tables.

Here below is my own assumptive 'straight upwardly increasing line' output levels curve based on the minimal information mentioned on the 1969 Alan Young report specs for the TG notes 36 to 91.

- 9.05 mVpp for the TG note 36 seems to low compared to the more common 10 mVpp to 11 mVpp levels of the TG note 36 on most TG’s that are in my TG spreadsheet.

- 22.62 mVpp for the TG note 91 seems too high compared to the more common 15 mVpp to 20 mVpp levels of the TG note 91 on most recapped or red mylar capped TG’s that are in my TG spreadsheet.

+9.05 mVpp for the TG note 36 seems too low compared to the more common 10 mVpp to 11 mVpp levels of the TG note 36 on most TG’s that are in my TG spreadsheet.

+

+22.62 mVpp for the TG note 91 seems too high compared to the more common 15 mVpp to 20 mVpp levels of the TG note 91 on most recapped or red mylar capped TG’s that are in my TG spreadsheet.

The following measurements would be taken directly from the TG terminal strip.

<pre>

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13 329 70.00

</pre>

The earlier era T-series organs seem to have had a very high treble calibration with the output levels of the TG notes 73 to 91 continuing upwards until the high treble TG notes 85 to 91 reached up to somewhere in the 30 to 35 mVpp region (10.61 to 12.32 mV RMS ).

- I did some modification and repair work on a friend's 1970 T-300 organ with the high treble calibration and the sound was very thin and nasal sounding and I recalibrated the TG to have a similar output curve as that of the B3 , C3 , A100 etc organs and doing this significantly improved the sound of the 1970 T-300 organ.

+

+ I did some modification and repair work on a friend's 1970 T-300 organ with the high treble calibration and the sound was very thin and nasal sounding and I recalibrated the TG to have a similar output curve as that of the B3 , C3 , A100 etc organs and doing this significantly improved the sound of the 1970 T-300 organ.

It is possible that enough people might have complained about this nasal sound with the result that Hammond seem to have gone back to the more normal standard post 1956 type TG calibration for the later era T-series and the XTP organs. The T series and the XTP TG's only had the TG notes 18 to 91.

As an example of very thin and nasal sounding high treble calibration of the earlier era T-series organs , the following measurements were taken directly from the TG terminal strip of my friend's 1970 T-300 before I recalibrated the TG to have a much better sounding B3/C3 etc type TG output curve. Note that the TG of the

@@ -912,9 +914,9 @@

Out of curiosity I have recalibrated the whole TG of my 1962 C3 a few times in order to find out what kinds of TG output curves produce the best sound and currently I have a non stock customized louder and fatter than stock sounding recalibrated TG output curve.

An advantage of the louder than stock TG output curve of my 1962 C3 is that there is a noticeably improved signal to noise ratio because the louder tone wheel signals now mask some of the background mechanical rumble and hum that is often audible under some of the TG notes especially when playing on the upper octaves of the keyboards.

-Even though the pickups are now closer to the ~~ton~~ wheels , the sine wave quality of the tone wheels still sounds normal like that of a stock organ. However there is a limit as to how close you can bring the pickups to the tone wheels before the sine wave quality starts to sound dirtier and more warbly thus spoiling the organ sound and I think that the current recalibrationof my 1962 C3 is near the limit and if I try to bring the pickups closer to the tone wheels than what they are now, then the tone wheel sine wave quality will start to deteriorate and thus spoil the organ sound .

+Even though the pickups are now closer to the tone wheels , the sine wave quality of the tone wheels still sounds normal like that of a stock organ. However there is a limit as to how close you can bring the pickups to the tone wheels before the sine wave quality starts to sound dirtier and more warbly thus spoiling the organ sound and I think that the current recalibrationof my 1962 C3 is near the limit and if I try to bring the pickups closer to the tone wheels than what they are now, then the tone wheel sine wave quality will start to deteriorate and thus spoil the organ sound .

As well as the louder overall output levels of all the TG notes 1 to 91, I have recalibrated the TG output curve to be more like that of the pre 1956 TG output curves that had stronger bass and midrange levels thus producing a fatter organ sound.

I am aware of the potential dangers or the pickup rod hitting a tone wheel whilst recalibrating the TG and I have the proper voltage meters to do a proper TG recalibration

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Interestingly after I installed the red mylar capped tray of the 1970 T-300 into my 1962 C3, the output levels of the TG notes 49 to 91 then became noticeably louder than what they were with the original recapped capacitors tray of my 1962 C3. The inductor coils of the brass tray that was originally in my 1962 C3 have the dark brown enamelled wire around the bobbins whilst the inductor coils from the 1970 T-300 brass capacitors tray have the bright red enamelled wire around the bobbin.

It would appear that the inductor coils with the bright red enamelled wire used in the late 60's or early 70's organs produced a higher Q or resonance levels than the inductor coils with the dark brown enamelled wire used in the early 1960's organs.

- The stock complex waveform TG notes 1 to 12 of my 1962 C3 sounded mediocre to my ears so therefore after listening to the warmer fatter sounding characteristic of the pedal bass notes of the L-100 series organs, I decided to apply this approach to the complex waveform TG notes 1 to 12 of my 1962 C3.

+The stock complex waveform TG notes 1 to 12 of my 1962 C3 sounded mediocre to my ears so therefore after listening to the warmer fatter sounding characteristic of the pedal bass notes of the L-100 series organs, I decided to apply this approach to the complex waveform TG notes 1 to 12 of my 1962 C3.

To do this, first I very carefully cut off the 16 ohms grounding shunt resistance wires that are wrapped around the top of the phenolic bobbins of the pickup coils of the TG notes 1 to 12 and this resulted in significantly louder output levels for the complex waveform bass TG notes 1 to 12. The TG notes 1 to 12 were now closer to the levels of the L-100 series TG notes 1 to 13.

After some experimentation I decided to ground out each of the TG notes 1 to 12 with 100 uf resistors connected between the TG terminal strip and the TG chassis. Doing this has resulted in much mellower and fatter sounding bass TG notes 1 to 12 and these TG notes now do sound more like the filtered pedal bass TG notes 1 to 13 of the L-100 organs and this new sound is noticeably better sounding to my ears than the stock complex waveform TG notes 1 to 12.

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