TWG filter cap question

[Sweet Pete]

Hey all,

I measured/sorted my PIO caps for the purpose of recapping this '37 BCV.
I will be using an AO28 preamp in it; so my questions are;

Will the measurements of TWG outputs be much different than a V preamp?(My V preamp is not functioning!)
Comparing various output curves they all seem to be similar readings? BCV might have a little more output?
I might find the BCV genny too bright compared to a -2/-3 so there must be a way to dull down the AO28 tone?

The BCV will have a -2 drawbar base/-2 preset panel(split vibrato); allowing the chorus genny drawbar to function as normal.
The V preamp shelf will easily accomodate an AO28.....
I'll leave the M3 perc switches in the end block and 'snake' it to a shelf below the lower manual,hung from the old RythmII brackets......
should slide in/out just about right!
Ergonomics will be different,I already deal with a TrekII TP-2B on my B2 so different locations are fine with me.

[kziss]

Hi Pete.

Will the measurements of TWG outputs be much different than a V preamp?(My V preamp is not functioning!)
Comparing various output curves they all seem to be similar readings? BCV might have a little more output?
I might find the BCV genny too bright compared to a -2/-3 so there must be a way to dull down the AO28 tone ?

The TG output levels as shown in millivolts peak to peak (mVpp) in my TG data spreadsheet are taken directly from the TG terminal strip so therefore the TG output signals present on the TG terminal strip are BEFORE the TG output signals have passed through the manual wiring and the drawbar matching transformer and the organ preamp, so this means that the TG output levels from the TG terminal strip are not in any way affected by the frequency responce or the output levels of the organ preamp.

Judging by the measured output curves in the TG data spreadsheet of the recapped 1930's TG's, including the Model A, BC, and Model E TG's, the overall output levels of the bass and the lower midrange and the midrange TG notes are set at slightly lower levels than that of the 1940's to 1970's TG's, but the treble TG notes of the recapped 1930's TG's are set at somewhat higher levels with the highest treble TG notes continuing to progressively taper upward up to approximately 25 mVpp, whilst most of the recapped 1940's to earlier 1960's TG's as well as the most of the red mylar capped 1960's and 1970's console organ TG's have the TG notes 73 to 84 set at a straight line level of approximately 20 mVpp and the highest treble TG notes 85 to 91 then progressively taper down from 20 mVpp to around 16 or 17 mVpp.

Because of these differences in the factory TG calibration of the 1930's organs, I assume that your recapped 1937 BC TG will have a brighter sounding treble response compared to that of a 1940's to 1970's recapped or red mylar capped TG.

I have never had access to a properly functioning Model A/BC preamp or a BV/ CV preamp or a -2 series AO10 preamp so that I could do A/B listening comparison tests, so therefore I am not certain about how different the tonality or the output levels of these earlier era preamps are like compared to the AO28 preamp, but people have written on the forums that the 1930's and 1940's organ preamps have a brighter or more "raw" tonality which allows the key click and the leakage "air" to be more prominent whilst the AO28 preamp has a duller or darker sounding tonality because of the built in treble cut filtering produced by the feedback capacitors in the various valve stages.

A very important factor in the sound of your 1937 BCV is whether the manuals are the earlier non tapered type or if they are the tapered type.
Assuming that your BCV has the original stock manuals, if the organ serial number is below 5075, then it will have the non tapered manuals , but if the serial number is 5075 or higher, then the manuals will have the manual tapering scheme.

If your BCV manuals are the earlier non tapered type, then your BCV manuals will produce a noticeably brighter treble response as well as a deeper bass response similar to the H-100 series or the R-100 series or the X-77 organs from the 1960's and 70's which also had the non tapered manuals as did all the spinet organs.

If your BCV manuals do have the manual tapering scheme, then your BCV manuals will produce a similar sound to that of a BV/ CV and a -2 series and a -3 series organ.

If the recapped BCV TG is too bright sounding, then you can recalibrate it to produce a more typical B3 type output curve as seen in the TG data spreadsheet. Instead of recalibrating, you can also bring down the levels of the treble TG notes by wiring up capacitors in parallel with the new capacitors therefoby in effect deliberately recreating the effect of aged drifted up wax paper capacitors.

You can also dull down the AO28 tonality by turning down the Tone Control dial, but doing this will also dull down the key click and the leakage "air", so therefore if you want to retain the key click and the leakage air, then it is best to bring down the excessive brightness by recalibrating the TG or by wiring up capacitors in parallel with the too loud treble TG notes.

All the best.
Kon.

[Sweet Pete]

Kon,

Thank you for your precise explanations of the different manual impedances and the relation between treble and keying.
Nice to know the TWG output measurements are taken right off the genny terminal strip!

I thoroughly enjoy this '37 BCV right off the matching transformer line level into a Ventilator!
The manuals have no tapering.
Way down no foldback bass as it should be IMO.The spit more than makes up for non complex wheels!
Not so much on the R and H gennys with non click keying though.
I'm trying to retain the overall brilliance of the chorus genny mixture without over-attenuating the top half octave of tones.
Will substitute caps 'before peaking'. Some of these .1 are low( .083-.089) and will be just about right i suspect doubled up? .155 or so?
PIO are way more forgiving than other types IMO. Heck,that's what it came with back in '37! Mind you those weren't painted or glass sealed either.....
Will look at the Q of each inductor 'in circuit' on these old Heathkit impedance bridge and Q filters and tune the thing back to it's former glory.
Even if these are 1% out of true they will still be as close or closer to my targets than a scope.
At 64 years of age 3db is an optimistic target without a meter LOL.

Wes has kindly offered to rewrite the original curve and/or modify it to my liking,using your tried and true methodology Kon!

Thanks again!

My recent M3 genny magnet pole replacement has given me useful skills in the magnet placement department so I'll be fine if I need to move one or two.

[kziss]

Hi Pete.

I thoroughly enjoy this '37 BCV right off the matching transformer line level into a Ventilator! The manuals have no tapering.

I use my 1969 H-111 organ in a similar manner.
I have cut out the extremely low resistance to ground "ladder" circuit tracks from the drawbar busbar circuit boards from both manuals and the pedals and I removed the three stock drawbar matching transformers, and I have replaced all these with a late 1940's or early 1950's era B2/C2/RT2 drawbar matching transformer.

I have rewired the pedal drawbar busbar outputs directly on to the lower manual drawbar busbar outputs so that this is the same set up as with all the A/B/C/RT etc console organs.

Removing the resistance "ladder" circuit tracks from the drawbar busbars and replacing this with the nine primary winding taps of the B2/C2/RT2 drawbar matching transformer set up has increased the output levels and fattened up the sound coming from the drawbars, and this has also removed some background hum as well as removing the constantly present background leakage sound which is a noticeable characteristic of all the cheaper designed 1960's/70's organ models including the E-100 series / H-100 series / L-100 series / T-series and the X-77 organs which all have the extremely low resistance to ground "ladder" circuit tracks on the drawbar busbar circuits.

I have also built a switchable box which connects to the secondary windings of the B2/C2/RT2 drawbar matching transformer now in my 1969 H-111, and this box contains the same resistor/ capacitor filter components and the same Tone Control circuit as that used on the Model A/BC/BV/CV etc organs.

This box includes a true bypass switch to completely switch out the filter so that the direct unfiltered secondary winding signal is produced, as well as a bass boost switch and a treble boost switch which work by switching out of circuit or by shorting out particular components from the 1930's/ 40's filter circuit.

There is also a 3-position switch which recreates the particular slight differences between the earlier Model A/BC and the BV/CV series filters, and with this switch the "early Model A" setting produces a mellower sound whilst the "BV/CV" setting produces a brighter treble.

With all this set up my non tapered H-111 manuals and drawbars now operate and sound in a similar way to that of the non tapered Model A/BC etc organs and the key click is now much more noticeable than what it was with the original stock H-111 set up.

I have also disconnected the extra high TG notes 92 to 96 and replaced these with the folded back TG notes 80 to 84 so that the normal regular treble foldback effect of most other Hammond console organs is produced instead of the "cheesy" sounding extended high "treble all the way up" wiring that the H-100 series and the X-77 organs have.

I have also modified the TG by removing the simpler capacitor-only filters of the TG notes 86 to 91 and I replaced these with the regular capacitor/ transformer filters which I salvaged from another TG so that the TG notes 86 to 91 sound like they do on most of the other Hammond organs.

I completely bypassed the 47 uf capacitor / 10 ohms grounding resistor hum filters from the TG notes 37 to 48 so that these TG notes sound fatter and more like that of the early era organs with the subtle low frequency undertones present underneath the sine wave TG note 37 to 49 frequencies.

I have recalibrated the whole TG as can be seen in my TG data spreadsheet.

Way down no foldback bass as it should be IMO.The spit more than makes up for non complex wheels! Not so much on the R and H gennys with non click keying though.

The reduced levels of key click spit on the R-100 series and the H-100 series organs is not caused by the TG or the keying, instead it is caused by the steeper treble cut present in the preamp circuits which tried to remove as much key click as possible.

Apart from the some particular things such as the sine wave bass TG notes 1 to 12 on the R-100 series and the H-100 series and the X-77 TG's, and the presence of the capacitor hum filtering for the TG notes 13 to 36 on the R-100 series TG's, and the simplified capacitor only filters for the TG notes 86 to 96 on the H-100 series and the X-77 TG's, the R-100 series and the H-100 series and the X-77 TG's are otherwise similar to that of other organ model TG's, and the keying on the R-100 series and the H-100 series and the X-77 organs are basically more or less similar to that of the other non tapered organs such as the pre 1937 Model A and BC organs.

The H-100 series and the X-77 organs do have the two extra "mixture" drawbars after the 1 ft drawbar.

My modified "de-sterilised" or "de-cheesed" 1969 H-111 as explained in the first paragraph produces noticeably more key click compared to the much reduced key click produced when the H-111 was in the stock condition.

Will substitute caps 'before peaking'. Some of these .1 are low( .083-.089) and will be just about right i suspect doubled up? .155 or so?

If you have a capacitor decade box, you can work out which capacitor values will peak the filters and thus produce the loudest output levels, and you can then write down the peak filter capacitor values for all the TG notes 49 to 91.
You can then decrease any excessively loud output levels to the desired levels by increasing the capacitance values with the capacitor decade box and then write down the appropriate capacitor values that produce the desired output levels for the TG notes 49 to 91.

PIO are way more forgiving than other types IMO. Heck,that's what it came with back in '37! Mind you those weren't painted or glass sealed either.....

Interestingly the output levels of the TG notes 49 to 91 of the wax capped 1937 BC TG that I measured were at similar levels to that of the wax capped early 1960's TG's that I have measured so therefore this suggests the possibility that the 70+ year old wax paper capacitors of the 1937 BC have drifted off spec to similar levels as the early 1960's wax paper capacitors.

All of the wax paper capacitors of this 1937 BC were covered with external cardboard tubes on them so therefore I wonder if these cardboard tubes have helped to better protect the capacitors from absorbing as much moisture and oil as they would have done if they were not covered with the cardboard tubes.

Most other wax capped TG's from the 1950's and early 1960's that I have come across did not have the external cardboard tube covers. This suggests the possibility that the 1930's wax paper capacitors might have been somewhat more stable than the non covered wax paper capacitors used in the 1950's and early 1960's.

I have been told that some 1950's wax paper capacitors have drifted up to 1 uf or even higher.

It would be good if you were able to measure and write down the actual values of all the wax paper capacitors of your 1937 BCV TG. It would be interesting to see how these measured values compare with the measured values of the 1950's and early 60's wax paper capacitors in my TG data spreadsheet.

Will look at the Q of each inductor 'in circuit' on these old Heathkit impedance bridge and Q filters and tune the thing back to it's former glory.

It would be interesting to know would be if the transformer filters of the 1930's TG's had a lower Q or resonance factor than the transformer filters used on the later era TG's. If this is so, then this would mean that the required capacitor values are less critical thus making the 1930's filters more forgiving.

If the 1930's transformer filters do actually have a lower Q or resonance factor than the later era transformer filters, then even with the filters peaked, the TG notes 49 to 91 of the 1930's TG's would likely be less pure sounding with more crosstalk and low frequency undertones present underneath the intended sine wave notes thus producing a fatter sounding tonality than that of the later era TG's.

Years ago I recapped the TG of my 1962 C3 with new capacitors, and some time later on out of curiosity I uninstalled and replaced the recapped brass capacitor tray of my 1962 C3 with a red mylar capped brass tray from a 1970 T-300 organ, and I then installed the recapped brass tray from my 1962 C3 into the 1970 T-300 organ.

I then re-measured the TG output levels of both organs, and the result was that the TG notes 49 to 91 of my 1962 C3 with the T-300 brass capacitor tray now in place had noticeably increased, whilst the output levels of the TG notes 49 to 91 of the 1970 T-300 TG with the recapped brass capacitors tray from my 1962 C3 now in place had noticeably decreased.

This indicates that the transformers with the dark brown enamelled wires from my 1962 C3 brass tray have a lower Q factor or resonance factor than the transformers with the bright red enamelled wires from the 1970 T-300 brass tray.

The fellow Organ Forum member David Hughes did a similar thing by replacing the recapped brass capacitors tray from his 1962 RT3 with the red mylar capped brass tray from an L-100 TG, and similar results happened, thus again indicating that the transformer filters of the later 1960's or 1970's TG's had a higher Q or resonance factor than the transformer filters of the earlier 1960's TG's.

You can see all of this in my TG data spreadsheet.

Wes has kindly offered to rewrite the original curve and/or modify it to my liking,using your tried and true methodology Kon!

It would be good to see the measured TG output levels of your 1937 BCV including with the original wax paper capacitors, and also with the new capacitors
before you recalibrate the TG, and also after you have recalibrated the TG.

With your approval, I would like to add all your 1937 BCV data into my TG data spreadsheet.

All the best.
Kon.

[Sweet Pete]

Thank you so much Kon!

No way I'm tearing down that organ without measuring everything.The preamp and rheo box are out for the 'ao28 fitting mock up'.
Sounds really great right off the MT!

When I first took possession I was taking everything out and stuffing in an A100!
Then I fixed the chorus genny run motor (M3 replacement),listened, and talked to a few folks, Sal Azzarelli included.
"Don't let the readings escape us!" he was adamant the community needs this info!
Wes seconded it,and everyone else agrees.I promise to take the readings when I do the work!
Not many first generation consoles that aren't rebuilt are still all working; so I'm thrilled to share the numbers with all of you!

Even though it didn't split, the C3 chorus setting on my Northern CV was the bees knees!
Really nice V upgrade workmanship on this BC circa 1950.The tech knew what he or she was doing!
The cabinet is one of a kind.The little growth rings on this Quebec dark walnut burl make it a keeper!
Fallboard(curved) is as nice as my B2!

I'm using a B+K VTVM that takes a few minutes to warm up.Works as intended,the Hammond service manual recommends these!
The quality of workmanship on these homemade Heathkit units is worth every penny I paid.They work as intended!
We'll find out what all the Q's are at the same time!

So let's see......the readings are taken from the 8' drawbar via alligator clip to the genny terminal strip,right?
I'll open the book.....

[kziss]

Hi Pete.

I promise to take the readings when I do the work!
Not many first generation consoles that aren't rebuilt are still all working; so I'm thrilled to share the numbers with all of you!

Yes it will be good to see all your readings. There are only a few measured 1930's organs in my TG data spreadsheet so therefore it is good to add more 1930's TG's into the spreadsheet, and especially so when both the wax capped readings and the recapped readings are shown so that we can get a better idea about what the 1930's era factory TG output curves were like compared to the later era factory TG output curves.

With the 1930's TG output curves that already are in the TG data spreadseet, it can be seen that apart from the treble TG notes, the rest of the other TG notes were set at a few mVpp lower than what they are in the TG's from the 1940's up to the 1970's.

It would also be good to see and add into the TG data spreadsheet the measured TG output curves of the Bill Beer (Keyboard Products) modified organs which were recalibrated by Bill Beer to produce what he described as a "hot bitchin', fat and balsy" sound.

So let's see......the readings are taken from the 8' drawbar via alligator clip to the genny terminal strip,right?

Measuring the direct TG output levels in millivolts peak to peak (mVpp) as they appear on the TG note terminal strip which is located along the length of the top of the back side of the TG is the best way to measure the TG output levels.

The TG notes on the TG note terminal strip of your BCV will most likely be somewhere in the 4 mVpp to 25 mVpp region so therefore the VTVM voltage meter or an oscilloscope or any other analogue or digital voltage meter needs to be able to accurately read AC millivolts peak to peak (mVpp) in this low level region.

To measure the TG output levels in mVpp, you connect one probe of the voltage meter to a convenient nearby grounding point such as the TG chassis or on to the hex screw head of one of the TG pickup tightening screws, or on to a nearby braided shielded wire etc, and you then connect the other probe on to each of the direct TG notes as they appear on the TG note terminal strip pins on the TG note terminal strip.

With the earlier era organs including the BC organs, the TG notes 1 to 91 are arranged in the sequential right to left order starting with the TG note 1 being on the far right side of the TG note terminal strip ( Start motor end) immediately to the left of the grounding wires which are at the very far right end of the terminal strip, and then each TG note sequentially proceeds in increasing number until the TG note 91 which is on the far left side ( Run motor end) of the TG note terminal strip.

PLEASE NOTE: When measuring the TG output levels, the probe must not be connected to the 8 ft drawbar or on to any other drawbars because the drawbars have an extremely low resistance to ground which would heavily load down the output levels of the TG notes.
As well as that, you would need to hold down each corresponding key in order to get the TG notes to pass through the manual resistance wires and the key contacts before passing through to the drawbars.

The Hammond service manual does recommend measuring the TG output levels in Volts by connecting the two probes of the voltage meter on to the two GG output terminals of the organ preamp, and to then connect one end of an alligator clip on to the fourth bar of the preset panel, and to then connect the other end of this alligator clip on to the TG notes on the TG note terminal strip.

However this method of measurement is of very dubious value because the TG note signals have to pass through the preamp which can result in different output level readings in different organs because of the differing gain factor and frequency response and overall condition of the actual valves on each preamp, as well as the condition and the tolerances of the resistors and the capacitors inside each preamp which would also affect the output levels and the frequency response.

As well as that, connecting the TG notes to the bar of the preset panel causes the TG notes to be heavily loaded down to ground because the preset panel bars which are connected to the primary winding taps of the drawbar matching transformer, have an extremely low resistance to ground.

The heavy loading down to ground imposed on the TG notes when they are connected to the bar of the preset panel is the reason why there is an abrupt and severe drop off in the output levels of the TG notes 44 and above in the TG note output levels chart shown in the Hammond service manual.

In the pre 1964 TG's, the TG notes 44 to 48 had the filter transformer coils so therefore the TG notes 44 to 48 with these transformer coils filters, along with the TG notes 49 to 91 with the capacitor/transformer coil filters are much more severely attenuated in level when they are loaded down than what the TG notes 1 to 43 are.

The only filtering on the TG notes 1 to 43 is a low value resistance wire connected between the output signals on each of the TG note 1 to 43 pickups, and the ground so therefore the TG notes 1 to 43 are not as severely loaded down and attenuated when they are connected to the bar on the preset panel.

All the best.
Kon.

[Sweet Pete]

Thanks Kon for the instructions and sharing your experience with us!
Will ground the VTVM to the genny and probe the terminal strip. More accurate and easier too.
I am more interested in an even tone than a bright tone when it comes to recapping the '37.

I had a gig free weekend coming up,and am now gigging Saturday.No worries,love to play.
I need Sunday off so will take a few hours after work Thursday and Friday to 'tech'.
I really look forward to this project,and will be taking my time.
Not as gratifying to me as playing,but enjoyable all the same.

Which reminds me there's an A100/122 in Burnaby that needs a service call.
Next week I guess.And a few other things like my new Behringer Model D.......
Just dialed up Behind The Eight Ball.....good enough for me! Who's to know......

[kziss]

Hi Pete.

I am more interested in an even tone than a bright tone when it comes to recapping the '37.

I also prefer a warm fat tonality instead of a bright sound.

With it's original stock calibration, the TG output curve of my 1969 H-111 had the regular output curve similar to that of 1960's red mylar capped B3's and other recapped or red mylar capped organs, and the resulting sound with the non tapered manuals was too nasal and shrill, especially in the upper octaves when the higher drawbars were pulled out.

I recalibrated the TG of my modified 1969 H-111 organ to produce a fatter sound by setting the lowest bass sine wave TG note 1 at 33 mVpp and I then set the TG notes 2 to 19 to gradually taper down with the TG note 19 being set at 20 mVpp, and I then set the rest of the TG notes 20 to 91 at 20 mVpp thus resulting in a "straight line" output curve instead of the normal regular stock upwardly rising curve.

This recalibrated "straight line" TG output curve brought up the bottom end and the lower mids whilst bringing down the upper mids and the treble so therefore this did noticeably improve and fatten up the overall sound and soften down the nasal shrillness, but the highest treble notes in the treble foldback region of the upper two octaves with all the drawbars pulled out did still sound a little too loud.

The wax capped 1937 BC organ with non tapered manuals that I played and measured several years ago did actually sound quite nice and it had a clear sound even though it has the 70 year old aged wax paper capacitors.

As well as that, last year I was allowed to play someone else's wax capped 1937 BC with non tapered manuals, and this also sounded clear without dullness.

With the nice sound of these two non tapered, wax capped 1937 BC organs in mind, I then decided to try out approximating a similar "aged wax capacitors sound" sound with my recalibrated 1969 H-111 by wiring up 0.120 uf ( 120 nf) capacitors in parallel with the stock 0.250 uf ( 250 nf ) red mylar capacitors of the TG notes 49 to 54, and I wired up 0.056 uf (56 nf) capacitors in parallel with the stock 0.1 uf ( 100 nf) red mylar capacitors of the TG notes 55 to 91, so therefore my 1969 H-111 TG now behaves much more like a 50-60+ year old wax capped TG.

This capacitor ageing modification has actually made my 1969 H-111 sound even better with a smoother sound and with a more "vintage" sounding character with subtle low frequency undertones and more crosstalk underneath the intended sine wave TG notes.

I have also modified the TG's of my two C3 organs by wiring up 3-position switches in parallel with the capacitors of the TG notes 49 to 91 so that I can select either the proper spec capacitor values for the "new organ" sound, and two degrees of wax capacitor ageing simulations.

The "50 years aged wax capacitors" switch setting uses the same capacitor values as the set up on my 1969 H-111 TG, by switching in circuit 0.120 uf capacitors in parallel with the 0.250 uf capacitors of the TG notes 49 to 54, and 0.056 uf capacitors in parallel with the 0.1 uf capacitors of the TG notes 55 to 91.

The more severely aged "60-70 years aged wax capacitors" setting switches in circuit 0.82 uf ( 820 nf) capacitors in parallel with the all the capacitors of the TG notes 49 to 91.

I chose the 0.82 uf capacitor values for the "60-70 years aged wax capacitors" switch setting because a well known and respected Australian Hammond organ tech and enthusiast who owns a wax capped 1958 B3 which he really loves the sound of, told me that he measured several of the wax paper capacitors in his 1958 B3 TG and that they measured in the 0.8 uf to 1 uf region, and that this extreme level of drift up is common in the wax paper capacitors from other 1950's era TG's that he has measured.

This 3-position capacitor value switching modifications is musically very useful in helping to get the tonal characteristics of organs from various eras, and I might eventually get around to wiring up this same 3-position switching set up on my 1969 H-111 TG.

I have modified the AO28 preamps of my two C3 organs with bass boost and treble boost controls, and setting the TG capacitor switches to produce the severely aged wax capacitor simulation settings and then turning up the AO28 treble boost controls helps to create a nice spitty key click sound and a more airy sounding leakage shimmer but without making the organ tonality become too bright or shrill which does happen when I turn up the treble boost controls whilst the TG capacitor switches are set to the "new organ" setting, and the subtle low frequency undertones present underneath the intended sine waves whilst the aged wax caps switch settings are switched on helps to fatten up the tonality.

If you find that your recapped 1937 BCV sounds too bright or too nasal or clinical, and you prefer it to have a more "aged vintage" sounding character, then you can do this by wiring additional capacitors in parallel with the new capacitors. You can experiment with different capacitor values to determine which values produce the desired effect.

All the best.
Kon.

[Sweet Pete]

Having another set of cap values ready to go must be a lot of work.
I will be content to 'un-dull' the overall top end a little,this 81 year old chugs along just fine when the chorus wheels are added.
However it doesn't exactly sparkle without the extra wheels! That leaves tones 44-91 in need of attention.
This organ was in use regularly until 2005. In use for 68 years and retirement isn't in the vocabulary.

My '63 wax/cardboard capped A100 remains the standard by which I judge an all 8's stop.My '73 B3 was like nails on a blackboard in comparison.
There is no way the tone of mylar/polyester etc. is the same as PIO. I would never use anything but original style.
Organs built after '65 have caps that seldom if ever drift.The organs built just before that had a different substrate in the PIO's than earlier versions.
Lots of those are in need of attention,however mine is perfect untouched and a survivor. Wouldn't change a thing.Even the preamp sounds fantastic.

Looking for the fat ballsy upper mids and emphasis on the doghouse to give the expression some bite on fortissimo!
Also enjoy and need an all 8's that doesn't run a fire drill........

[kziss]

Hi Pete.

Having another set of cap values ready to go must be a lot of work.

It took me many hours of boring work to wire up the forty three capacitor selector DPDT "centre off" switches for the TG notes 49 to 91.
I spent one day wiring up the capacitors on the switches and then mounting all these switches in a sequential numerical left to right 49 to 91 order on a long metal strip, and I then spent the other day doing the fiddly and cramped job of physically wiring up this switching network in parallel with the TG capacitors of my C3, whilst the manuals were raised.

The end result made all this fiddly boring labour worthwhile. In effect I now have three or more different sounding C3's inside one C3 because of the switching options.

Here is the metal strip with the capacitor switches on it.





Here are the capacitor switches with the wires going to the corresponding red mylar capacitors of my 1965 C3.



Here is the completed set up with the TG capacitor switching network in place underneath the lower manual of my 1965 C3.

That leaves tones 44-91 in need of attention.

The TG notes 44 to 48 only have transformer filter coils without any capacitors.

Interestingly, on the very earliest production Model A organs from 1935, the TG notes 49 to 54 also only have transformer coils without capacitors. There is one such 1935 Model A TG without the capacitors on the TG notes 49 to 54 in the TG data spreadsheet.

My '63 wax/cardboard capped A100 remains the standard by which I judge an all 8's stop.

It would be good to see the TG output levels of your good sounding 1963 A100, and to see how the levels of the wax capped TG notes 49 to 91from your 1963 A100 compare with that of other wax capped TG's from the 1950's and early 1960's that are in the TG data spreadsheet.

My '73 B3 was like nails on a blackboard in comparison.

Some late era TG's in the TG data spreadsheet have very uneven, sloppy looking output curves and with the treble TG notes set at excessively high levels which would result in a very shrill sound.

A shrill and nasal sounding 1970 T-300 organ that I modified originally had an excessively trebly TG calibration. It sounded much better after I recalibrated the TG to have a much more normal looking output curve.

There is no way the tone of mylar/polyester etc. is the same as PIO. I would never use anything but original style.

I have done A/B test experiments with different capacitor types but which all measured at the same uf value. These included a polyester greencap type, an MKT polyester type, a polypropylene type, a wax paper type, a ceramic type, and possibly a polystyrene type, and I tested these by connecting them with alligator clips on to the transformer filters of various TG notes within the various octaves in the TG note 49 to 91 range.
The resulting measured output levels as well as the audible tonality of the TG notes that I tested with the different capacitor types were all identical so therefore this A/B test led me to the conclusion that the different capacitor types do not affect the output level or the tonality of the TG notes, instead what really mattered was the actual measured uf value.

Having verified that there is no difference in the sound or output levels with the different capacitor types, this means that there is no need to use expensive or hard to find capacitor types for the TG application so therefore I used the cheaply and readily available polyester greencap capacitors to recap a few TG's, and I then recalibrated the TG pickups to produce the smooth output curve.

The polyester greencap capacitors are stable so therefore it is unlikely that they will drift up off spec.

I have also done a similar capacitors A/B test on my electric guitar Tone Control with different capacitor types but that were of the same measured uf value. These capacitors included a polyester greencap type, an MKT polyester type, a polypropylene type, a wax paper type, a ceramic type, a Russian K40Y-9 paper-in-oil type, a Russian K42Y-2 paper-in-oil type, and a vintage Sprague Bumblebee paper-in-oil type.

Once again all of these different capacitor types sounded and behaved identically so my conclusion here is that the only thing that matters with guitar Tone control capacitors is the actual measured uf value of the capacitor, so therefore once again there is no need to use the expensive or "unobtanium" magic mojo voodoo capacitor types such as the 1950's Sprague Bumblebee paper-in-oil capacitors that some people seem to uncontrollably salivate over in the electric guitar forums.

In my experience a cheap polyester greencap capacitor that measures at 0.022 uf behaves and sounds identical to a vintage exorbitantly priced Sprague Bumblebee paper-in-oil capacitor that measures 0.022 uf.

The exception to this is if the aged Bumblebee capacitor has become leaky and there is a measurable resistance which is low enough to affect the signal from the guitar pickup, and thus create the effect of a resistor being in parallel with the capacitor, and in this case the effect of the parallel resistance does affect the sound of the capacitor when the guitar Tone control is turned down.

This effect can easily be recreated by measuring the resistance ohms value of the leaky but "magic" sounding Bumblebee capacitor, and then wiring up a suitable resistor in parallel with a greencap or any other capacitor.

The Russian K40Y-9 and the K42Y-2 paper-in-oil capacitors still seem to be available from Russian or other ex-Soviet Union region based eBay sellers at reasonable prices, and because the 0.220 uf or 0.250 uf and the 0.1 uf values are generally not sought after by guitarists, this means that it might be possible to buy suitable bulk quantities of these Russian paper-in-oil capacitors for the TG at cheaper prices than what is charged for the 0.022 uf and the 0.047 uf values sought after by guitarists for their guitar Tone controls.

These Russian capacitors are a similar physical size as the wax paper capacitors and the red mylar capacitors thus making it more convenient to wire them up in place on top of the transformer filter coils.

Organs built after '65 have caps that seldom if ever drift.The organs built just before that had a different substrate in the PIO's than earlier versions.

I remember reading posts on the Organ Forum where it was mentioned that the particular wax paper capacitors used at the end of the wax capped TG era in 1963-64 were better quality and more stable than the earlier wax paper capacitors, and that some wax capped organs from the 1963-64 era sound bright and clear without needing to be recapped.

My 1963 L-102 organ TG originally had the "Gen Instr" branded wax paper capacitors, and the TG notes 49 to 91 had the typical reduced output levels similar to that of many other early 1960's wax capped TG's that are in the TG data spreadsheet.

As can be seen in the measured capacitors chart in the TG data spreadsheet, these particular "Gen Instr" brand capacitors from my 1963 L-102 have only drifted up to a relatively moderate level and nowhere near as badly as that of some of the 1950's era wax paper capacitors shown in the chart.

After I recapped the 1963 L-102 TG, the organ basically now produced a slightly brighter sounding version of it's previous wax capped tonality, so therefore the difference in the tonality after the TG recapping was not as dramatic as what it was with the console organs that I have recapped.

I am not sure, but I wonder if the less dramatic change in the tonality of my recapped L-102 is because the TG notes 49 to 91 are loaded down differently by the non tapered manuals of the L-100 series organs than how they are loaded down by the tapered manuals of the console organs.

Lots of those are in need of attention,however mine is perfect untouched and a survivor. Wouldn't change a thing.Even the preamp sounds fantastic.

My 1962 C3 organ was previously a home organ owned by a Roman Catholic priest, and my 1965 C3 organ was previously used in an Anglican church, so both C3 organs have had an easy life without ever having been used as gig organs or subjected to a corrosive damp atmosphere or a smoke filled atmosphere so therefore they are both in good electrical condition.

However as a preventative measure, I have fully rebuilt the AO28 preamp of my 1962 C3 with the Trek II CPR-28 kit that was sent to me as a gift from a Hammond enthusiast that I had helped, and I have partially rebuilt the AO28 preamp of my 1965 C3 by replacing all the electrolytic capacitors and also the other capacitors and resistors that are recommended to be replaced.

In both cases there was no change to the sound or the volume levels after I did these upgrades to the AO28 preamps so this indicates that both AO28 preamps were operating in good condition.

Also enjoy and need an all 8's that doesn't run a fire drill........

My two C3's and my L-102 organs never sounded overbearing with the all 8's setting, but my 1969 H-111 organ did sound too thin and bright before I modified and recalibrated the TG.

All the best.
Kon.

[Sweet Pete]

I performed the AC voltage leakage test. I've got 6.2 volts AC/PP everywhere and 15VRMS everywhere on the BCV.
Cue "Tore Down'.......from the 5 in A. And a 1....;>)
Can't feel any tingles and this B+K Model 375 VTVM is very accurate.
It sounds great 'as is' from the matching transformer so...
After a complete tear down I'll have a superb example of an early non-tapered all the way down console.

While it is still intact mods have been 'mocked up' and tested/fitted.
Three AO28's tested so far, the '73 sounds the best with this generator/matching transformer.
This one has treble dialed back a fair amount.Guessing the TWG's in '73 were bright? Mine sure was!
My spare CV matching transformer is a close match so I'll use a pair of those instead of the smaller newer 'can' type pair.
The preset panel swap (H100) and drawbar base swap (C2) are needed to maintain the start/run switch base intact and the chorus drawbar intact.
Seems the M3 cheekblock with perc controls fits nicely on a Mogami flex 'snake' so placing it conveniently won't be an issue.
The BCV drawbars, 'chromies', have less dead spots between numbers than the C2 ratchets! Keeping them for sure!

Should only take me a day to tear down,maybe less. AC wiring is the first thing to replace.

[enor]

The one issue I had when mating an AO-28 to an organ with untapered manuals, is that percussion becomes crazy loud! Innovative steps to reduce perc volume at the amp is needed.

[Sweet Pete]

Removed the amp/rheo 'plate',music rack desk and chorus generator to start with today.
No longer have 6.2 volts AC everywhere. Will try and test genny outputs next visit.

Thanks for the perc tip enor!