Conn 720

[Guest]

Greetings all,</P>


I'm still looking for an organ. I've found one locally; a Conn 720. It is very pretty, but the strings and reeds don't sound so great; it sounds like there's some static. I'm curious about what you all think. It's $300.</P>


In regards to the tone quality problem for those faulty groups, I'm thinking it may just be an issue of cleaning some contacts.</P>

[jbird604]

Re: Conn 720



D,</P>


I played a Conn 720 in a church for several years and would say itis pretty decent for its age and type. It has vacuum tube generators (using the widely available and cheap 12AU7 tubes)of a design used by Conn over a long period. There is a separate oscillator for each pitch, including all the way up to 2' high C. The pedals have a separate generator system just for the 16' stops.Eachoscillator outputs both a sine wave and a sharp pulse wave, the sine wave used for flutes and the pulse for most other voices.The 720 was a unique model in that the generators were specially built to produce a third output, a sawtooth wave, which was used only for the great unit diapason. This gave is a more realistic diapason than the lesser Conns that got the diapason from the pulse wave or by combining the pulse and the sine waves. The diapasons are also transistor-keyed just like the flutes, so they have a realistic attack and do not suffer from the vinyl-rod problem described below.</P>


It's fully AGO, of course, but has no pistons or other non-essentials. Should be a good practice organ.</P>


So the best parts of the 720 are the nice unit flutes, available at all the essential pitches on both manuals, the unit diapason at 8', 4', 2', and 1-1/3' pitches on the great, and the solid pedal. There is a good chime, which is just a mixture of flutes with sustain. As with any unit organ, there are drawbacks, but a unit pipe organ would have the same.The flutes are pure sine ways, like very dry "open" flutes, but sound surprisingly good. There is a built-in Leslie speaker, and that helps the flutes sound more lively. I believe there is a switch to channel either the flutes or the strings into the Leslie, and the Leslie can be off, slow, or fast.</P>


There is no celeste as such, though the Leslie gives a nice slow celeste-like effect. The "chorus" control found on most Conns is not very useful as it makes things sound too sour for my taste. By the way, be sure to get it tunednow and then, as theoscillators will get out of tune in time. You may find it sounding pretty awful if the present owner hasn't had it tuned in many years.</P>


The bad quality of the reeds and strings is due to the way they are keyed.(The flutes and unit diapason are NOT keyed like this. They use a metalic rod and should work perfectly.)Conn used a vinyl-graphite coated rod for keying the reeds and stringsto reduce "pop" and make the attack more subtle, but alas, the coating deteriorated quite rapidly and the stops thus keyed became very unreliable. You will notice that the volume may differ radically from one note to the next due to the extreme variability of the resistance of this coating and also due to wear and imperfections in the coating. Some techs have claimed they could repair these rods by re-coating them with graphite in some manner. The truly best way to repair this is to have a tech replace the vinyl rods with gold-clad rods available from the Conn service company. When the gold rods are installed all the irregularities go away. However, there is a slight modification to the circuitry that needs to be made, as the level and tone quality of the stops is also altered somewhat by the changing of the rods.</P>


$300 is probably a good price, if the organ is working. It should be quite usable just as it is, but if you decide to replace the vinyl rods that job could run into a few hundred dollars itself. So you wouldn't want to have any more than that invested in it. Good luck.</P>


John</P>
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[Guest]

Re: Conn 720



John,</p>

Thanks for the information; I've found it very helpful. I think I'll try to look at it on Saturday; I'm really looking forward to playing again.</p>

-Donn
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