Hammond M-100 very little treble.

[briguy1960]

This is a follow up post to my "low M-100 output" post. Now I have had several Hammonds in my nearly 6 decades on this rock. Yes I know spinets do not have foldback but still even with just the first four drawbars the sounds really wimps out in the last octave or so. This has the wax TG caps. What is the easiest way to determine if the TG is not putting out high frequencies or if they are being attenuated by the A0-29 Apart from low frequencies I still don't think I am getting the kind of volume I would expect out of a push pull 6v6 amp. I have a real 1969 deluxe and princeton too and those sucker are both LOUD.

As Always

TIA

B

[Sweet Pete]

Now that the newest AO29 is 50 years old.......it's more likely the AO29 amp in your M100 needs attention.
I've got a 1965 red capped M111 that has the same symptoms.It's the AO29 that is dull,not the genny.
The earlier wax capped genny will be duller to begin with by now.
This M111 still has normal overall volume,just dull on the trebles because of the amps.
Also have a '64 M102 that still has a nice bright sound,it lived an easy living room life with regular maintenance,
so an AO29 can survive longer if treated nice......and played regularly.

Willing to bet your guitar amps get more use.Your Hammond has 'atrophy' like most of them.
Very few of these organs actually get played.

If you have a tube tester (or get them tested).....is a great place to start!
Getting that power supply quiet with new caps will reveal just how dull or bright your genny is.
More likely the AO29 needs a power supply recap at least.
Once you hear the amp properly,you might decide you like the aged wax caps!
The ones on this 1953 B2 are staying put! The 1937 BCV improved considerably with new TWG caps.
They are all different.....

[tpappano]

FWIW, recently acquired a '63 M100 which also does not seem to produce as much volume as I think it should. I have a '55 M3 sitting next to it which puts out substantially more. On the M3 I did replace the TG caps, adjusted some of the pickups to smooth out the levels and I disabled the click filters. On the M100 all I have done so far is replace the TG caps, I have not gotten into the amp yet. Curiously, the M3 produces more volume than the M100 with less actual voltage being applied to the speaker! It makes me suspicious of the M100's speakers more than the amp. I intend to do a speaker substitution test to see if perhaps the M100's speakers are crap.

[briguy1960]

FWIW I did try hooking up the speaker outs to a leslie 120 and it was somewhat louder but I think Pete is right, the amp caps need some attention.

B

FWIW, recently acquired a '63 M100 which also does not seem to produce as much volume as I think it should. I have a '55 M3 sitting next to it which puts out substantially more. On the M3 I did replace the TG caps, adjusted some of the pickups to smooth out the levels and I disabled the click filters. On the M100 all I have done so far is replace the TG caps, I have not gotten into the amp yet. Curiously, the M3 produces more volume than the M100 with less actual voltage being applied to the speaker! It makes me suspicious of the M100's speakers more than the amp. I intend to do a speaker substitution test to see if perhaps the M100's speakers are crap.

[tpappano]

Looking at the schematic, C14 is a cathode bypass that is common to four different amplifier stages. If that guy is dried up it would definitely reduce the amp's output. Oddly, the one on my M3 was still in spec. I'll check the one in the M100, but I'm still suspicious of the speakers. Is it possible that the Alnico "permanent" speaker magnets in the M100 aren't so permanent after 55 years? The M3 has the 'field' coil so it would not have that problem 8)

[jdoc]

speaker efficiency is a real thing

[briguy1960]

Yes except for the fact that the bass pedals are really loud. Unless speaker sensitivity is also frequency dependent Which does not make sense to me

speaker efficiency is a real thing

[tpappano]

I did a little tinkering with the M100 today. I checked the signal levels at the "A" terminal (the non-vibrato signal from the matching transformers) on the amp. Pulling only the 2nd harmonic drawbar, there is a *very* pronounced rolloff, about 20 db, from the lowest key to the highest. Disconnecting C6 and C1 (the "click" filter caps) pretty much flattened out the response and now the M100 sounds similar to the M3 (which also had C6 and C1 disconnected). Without the filters I observed the treble response of the M100 speakers was not quite as good as the M3. The highest few tones were almost inaudible on the M100 but I could hear them on the M3.

[enor]

I did a little tinkering with the M100 today. I checked the signal levels at the "A" terminal (the non-vibrato signal from the matching transformers) on the amp. Pulling only the 2nd harmonic drawbar, there is a *very* pronounced rolloff, about 20 db, from the lowest key to the highest. Disconnecting C6 and C1 (the "click" filter caps) pretty much flattened out the response and now the M100 sounds similar to the M3 (which also had C6 and C1 disconnected). Without the filters I observed the treble response of the M100 speakers was not quite as good as the M3. The highest few tones were almost inaudible on the M100 but I could hear them on the M3.

If, after altering the filtering in the preamp, you still can hardly hear the topmost frequencies ... and it's a wax capacitor organ ... well you know where I'm going with this. Check the capacitance of a couple of your tone generator filter caps. If they haven't doubled in value (or more) I'd be surprised.

[tpappano]

If, after altering the filtering in the preamp, you still can hardly hear the topmost frequencies ... and it's a wax capacitor organ ... well you know where I'm going with this. Check the capacitance of a couple of your tone generator filter caps. If they haven't doubled in value (or more) I'd be surprised.

Oh yeah, after my M3 experience the TG caps are the first things I attacked when I got the M100 8) The organ sounded pretty dull, the tg and delay line caps had drifted up about 60% in value. It perked up quite a bit but I have not yet adjusted any of the pickups.

On the higher tone# sounds from the speakers, my meter said they should be there but you could barely hear them.