Philharmonic tone control.

[jonathan dollimore]

As I understand it, on the Philharmonic, the tone control is part of the sensitivity control.  And since the latter is switched out when on phono, it means there’s no facility for a treble cut on phono. I am wondering about the design philosophy of this arrangement since, with some 1950's 78 records I would quite like a little treble cut.

[Norman S Braithwaite]

The Philharmonic has separate bass and treble controls plus a record scratch suppressor.  All of these controls operate completely independent of the sensitivity control.

Norman

[Russ Webb]

On the Phantom I just finished, the scratch suppressor on/off is at the high sensitivity end of the sensitivity control - which isn't good. If you turn on the scratch suppressor while on a shortwave station you can hear the receive level come up just before the suppressor comes on.

Not that it matters on a Philharmonic, but they had some odd switch combinations.

[David C. Poland]

The radio/phono switch of the Philharmonic pointer model (and early BOL dial 6 control models) is on the sensitivity control pot. (below band switch, to the left). Later BOL dial 8 control sets would be the same.

Thus, when fully counter-clockwise to throw the radio/phono switch, the sensitivity is reduced to minimum when switched to phono. This switch does not affect either tone control, nor the scratch suppressor circuit. If your switch is on a different control, perhaps prior service has altered your example. Or perhaps the control escutcheons are not properly positioned leading to confusion.

+

Ross - seems your Phantom sensitivity pot is improperly wired - a replacement control?

+

The later 8 control BOL Philly model added 2 controls:  the treble control has been removed from the selectivity/fidelity control to become one of the additional 2 new controls. The other being the relocated scratch suppressor switch. 

+

NOTE For remote control Philharmonics (and Phantoms) , the radio/phono switch is inside the chassis and is operated by a relay that moves a triple pole wafer switch, one pole of which decreases sensitivity. The tone controls are not affected. Also, the location of the Philly volume and bass controls are reversed to allow room for the motor and gears to operate the volume control.

+

So, the selectivity control does effect the tonal range of radio programs - it effects the fidelity of the program by narrowing or broadening the IF amp curve to affect the audio frequency range,  which is helpful on short wave reception or weaker broadcast stations suffering from adjacent station interference. On phono, the fidelity control would be advanced as desired: on earlier models using the selectivity control - or the later BOL models, with the separate treble control.

NOTE: The Scratch suppressor control works for both radio or phono. This 2 tube circuit is dynamic: when engaged, it operates during lower volume audio when record scratch would be noticed on records or radio hiss, but not for higher volume when the music would mask record scratch or station hiss. Consequently, at low volume material, the high frequency audio is reduced. Probably most beneficial for classical music.

 

[jonathan dollimore]

David, yes, what you describe is what I have, although my scratch control isn’t working (mine is a pointer dial philharmonic). That is, the phone switch is on the sensitivity control. And there is no separate tone control.

David C. Poland said:

The radio/phono switch of the Philharmonic pointer model (and early BOL dial 6 control models) is on the sensitivity control pot. (below band switch, to the left). Later BOL dial 8 control sets would be the same.

Thus, when fully counter-clockwise to throw the radio/phono switch, the sensitivity is reduced to minimum when switched to phono. This switch does not affect either tone control, nor the scratch suppressor circuit. If your switch is on a different control, perhaps prior service has altered your example. Or perhaps the control escutcheons are not properly positioned leading to confusion.

+

Ross - seems your Phantom sensitivity pot is improperly wired - a replacement control?

+

The later 8 control BOL Philly model added 2 controls:  the treble control has been removed from the selectivity/fidelity control to become one of the additional 2 new controls. The other being the relocated scratch suppressor switch. 

+

NOTE For remote control Philharmonics (and Phantoms) , the radio/phono switch is inside the chassis and is operated by a relay that moves a triple pole wafer switch, one pole of which decreases sensitivity. The tone controls are not affected. Also, the location of the Philly volume and bass controls are reversed to allow room for the motor and gears to operate the volume control.

+

So, the selectivity control does effect the tonal range of radio programs - it effects the fidelity of the program by narrowing or broadening the IF amp curve to affect the audio frequency range,  which is helpful on short wave reception or weaker broadcast stations suffering from adjacent station interference. On phono, the fidelity control would be advanced as desired: on earlier models using the selectivity control - or the later BOL models, with the separate treble control.

NOTE: The Scratch suppressor control works for both radio or phono. This 2 tube circuit is dynamic: when engaged, it operates during lower volume audio when record scratch would be noticed on records or radio hiss, but not for higher volume when the music would mask record scratch or station hiss. Consequently, at low volume material, the high frequency audio is reduced. Probably most beneficial for classical music.

 

[David C. Poland]

Jonathon, For your pointer Philly:

The BASS control is lower left of the tuning knob. (be sure you replaced the 4 caps inside the bass tone reactor, inside the rectangular chromed box between the expander 6L7s and 3rd audio 6J5s).

IMG_1204.JPG

The TREBLE pot is integrated with the selectivity/fidelity control, on the same control shaft (far left control). The logic is to decrease the treble in conjunction with narrowing the selectivity which reduces the higher frequency audio anyway for radio programs, and allow using same control for reducing treble on records. 

As for the scratch suppressor switch, action is only noticeable at lower volume material as it is designed to allow all available high frequency tones through at higher volume levels when you would not notice record scratch of old dirty or worn out records. 

Suggest you re-read the owners manual for these controls.

[Brad Winder]

David, thanks for the control explanation! I am working on installing a Philly into a cabinet that originally held a Phantom, and I will double check the escutcheon positions before I install them. I was going to position them as per a photo from the library, but I will make sure first.

David C. Poland said:

The radio/phono switch of the Philharmonic pointer model (and early BOL dial 6 control models) is on the sensitivity control pot. (below band switch, to the left). Later BOL dial 8 control sets would be the same.

Thus, when fully counter-clockwise to throw the radio/phono switch, the sensitivity is reduced to minimum when switched to phono. This switch does not affect either tone control, nor the scratch suppressor circuit. If your switch is on a different control, perhaps prior service has altered your example. Or perhaps the control escutcheons are not properly positioned leading to confusion.

+

Ross - seems your Phantom sensitivity pot is improperly wired - a replacement control?

+

The later 8 control BOL Philly model added 2 controls:  the treble control has been removed from the selectivity/fidelity control to become one of the additional 2 new controls. The other being the relocated scratch suppressor switch. 

+

NOTE For remote control Philharmonics (and Phantoms) , the radio/phono switch is inside the chassis and is operated by a relay that moves a triple pole wafer switch, one pole of which decreases sensitivity. The tone controls are not affected. Also, the location of the Philly volume and bass controls are reversed to allow room for the motor and gears to operate the volume control.

+

So, the selectivity control does effect the tonal range of radio programs - it effects the fidelity of the program by narrowing or broadening the IF amp curve to affect the audio frequency range,  which is helpful on short wave reception or weaker broadcast stations suffering from adjacent station interference. On phono, the fidelity control would be advanced as desired: on earlier models using the selectivity control - or the later BOL models, with the separate treble control.

NOTE: The Scratch suppressor control works for both radio or phono. This 2 tube circuit is dynamic: when engaged, it operates during lower volume audio when record scratch would be noticed on records or radio hiss, but not for higher volume when the music would mask record scratch or station hiss. Consequently, at low volume material, the high frequency audio is reduced. Probably most beneficial for classical music.

 

[Kent King]

Definitely place them based on your review of the specific set. I'm working on a remote control Philly, and as Dave noted, there are differences in the RC sets because of the mechanical parts. But I have seen other differences over the years. As I am restoring this Philly, I have verifying each control function before I close it up.

Kent

Brad Winder said:

David, thanks for the control explanation! I am working on installing a Philly into a cabinet that originally held a Phantom, and I will double check the escutcheon positions before I install them. I was going to position them as per a photo from the library, but I will make sure first.

David C. Poland said:

The radio/phono switch of the Philharmonic pointer model (and early BOL dial 6 control models) is on the sensitivity control pot. (below band switch, to the left). Later BOL dial 8 control sets would be the same.

Thus, when fully counter-clockwise to throw the radio/phono switch, the sensitivity is reduced to minimum when switched to phono. This switch does not affect either tone control, nor the scratch suppressor circuit. If your switch is on a different control, perhaps prior service has altered your example. Or perhaps the control escutcheons are not properly positioned leading to confusion.

+

Ross - seems your Phantom sensitivity pot is improperly wired - a replacement control?

+

The later 8 control BOL Philly model added 2 controls:  the treble control has been removed from the selectivity/fidelity control to become one of the additional 2 new controls. The other being the relocated scratch suppressor switch. 

+

NOTE For remote control Philharmonics (and Phantoms) , the radio/phono switch is inside the chassis and is operated by a relay that moves a triple pole wafer switch, one pole of which decreases sensitivity. The tone controls are not affected. Also, the location of the Philly volume and bass controls are reversed to allow room for the motor and gears to operate the volume control.

+

So, the selectivity control does effect the tonal range of radio programs - it effects the fidelity of the program by narrowing or broadening the IF amp curve to affect the audio frequency range,  which is helpful on short wave reception or weaker broadcast stations suffering from adjacent station interference. On phono, the fidelity control would be advanced as desired: on earlier models using the selectivity control - or the later BOL models, with the separate treble control.

NOTE: The Scratch suppressor control works for both radio or phono. This 2 tube circuit is dynamic: when engaged, it operates during lower volume audio when record scratch would be noticed on records or radio hiss, but not for higher volume when the music would mask record scratch or station hiss. Consequently, at low volume material, the high frequency audio is reduced. Probably most beneficial for classical music.

 

[jonathan dollimore]

Thank you David - as always, and sorry for my obtuseness here: in mitigation: my Philharmonic tuner has been down for the last 6 months and better minds than mine have  been unable to find the fault. Which is why I’ve been playing around with a phono input. Can you confirm that the selectivity/fidelity control should also work on phono? Mine does not. No surprise!

David C. Poland said:

Jonathon, For your pointer Philly:

The BASS control is lower left of the tuning knob. (be sure you replaced the 4 caps inside the bass tone reactor, inside the rectangular chromed box between the expander 6L7s and 3rd audio 6J5s).

IMG_1204.JPG

The TREBLE pot is integrated with the selectivity/fidelity control, on the same control shaft (far left control). The logic is to decrease the treble in conjunction with narrowing the selectivity which reduces the higher frequency audio anyway for radio programs, and allow using same control for reducing treble on records. 

As for the scratch suppressor switch, action is only noticeable at lower volume material as it is designed to allow all available high frequency tones through at higher volume levels when you would not notice record scratch of old dirty or worn out records. 

Suggest you re-read the owners manual for these controls.

[David C. Poland]

Yes. The treble control (potentiometer)  just rides on the same shaft that controls the selectivity mechanism.

The selectivity mechanism is the set small air caps across the back of the chassis that tune or de-tune the IF amp and is part of the superset tuner section.

The treble and bass controls are in the audio section, from the radio/phono switch ahead of the volume control onward to the amp. All the treble control does is use a cap and variable resistor (the treble pot riding on the selectivity shaft) to short higher frequency audio to ground - just like the tone control did on the earlier AW-12 and AW-15 models.

Unless your resistor pot is shorted to ground or the cap is, then look elsewhere for your problem.

Is your audio amplifier functioning? - touching the output side of the volume control with finger should produce loud hum. And if not, work back from the 6L6's on the amp to each stage towards the volume control.

Also, beware of the bass tone reactor. two chokes and 4 caps inside and if one is shorted, could damage that dual pot bass control. Be very aware if the bass control gets scratchy, leaking caps there may damage that bass control.

Is your radio/phono switch on the back of the sensitivity working? or is it stuck? or broken? finger test. that switch is a double pole switch (not a mere on/off) to switch between phono and radio.

[Scott Seickel]

There is no treble potentiometer anywhere on the dial pointer sets.  The selectivity control has a series of 5 mica capacitors on the back of it to help change the tone, but the lack of treble problem was addressed in later sets. 

[David C. Poland]

Scott - interesting. You have a real early production example? maybe with 83V rectifier?

Mine is early 1938 with double KK prefix set #. has VR tube behind the tuning cap. has the treble control as I described

[Norman S Braithwaite]

The potentiometer associated with the selectivity control adjusts bias to compensate for a change in gain when adjusting selectivity.  This keeps the volume of the receiver approximately constant while changing selectivity.  Unless, of course, someone repurposed the potentiometer as a treble control.

Norman