Tube amp for 800ohm Philips 9710

[Folter]

Hello.
Fun you are interested in this rather rare subject.
I had this a lot at home. Started in 1998 and stopped with it November last year.
Just ask here what you want to know and look to my site HiQGN which is in Dutch, sorry for that.
Also in LH I wrote something about this subject, even 13 years ago.

Thank you! First of all, I want to know how to connect two broadband speakers to one column (parallel or series)? I have a pair of AD 3700 AM. I plan to buy a couple more of the same. The second question is: how critical is the deviation of the speaker resistance from the nominal 800 Ohm? If the speaker, when measured by a tester, gives, for example, 500 Ohm? Will there be a load on the amplifier?
Vitali

[RR1957]

Thank you! First of all, I want to know how to connect two broadband speakers to one column (parallel or series)? I have a pair of AD 3700 AM. I plan to buy a couple more of the same. The second question is: how critical is the deviation of the speaker resistance from the nominal 800 Ohm? If the speaker, when measured by a tester, gives, for example, 500 Ohm? Will there be a load on the amplifier?
Vitali

In series is not advisable , 2x 800ohm = 1600 ohm for an amp.
What amp are you going to use? OTL?

[analogadikt]

The second question is: how critical is the deviation of the speaker resistance from the nominal 800 Ohm? If the speaker, when measured by a tester, gives, for example, 500 Ohm? Will there be a load on the amplifier?
Vitali

800 ohms is the specification of the driver's impedance, not the DCR of the voice coil. Please search for "resistance vs. impedance" to understand the difference.

Regards,

Anwesh

[Folter]

In series is not advisable , 2x 800ohm = 1600 ohm for an amp.
What amp are you going to use? OTL?

Philips AG9018 amplifier. Three contacts for connecting acoustics. Three contacts on the speaker itself (AD 4690). How to assemble all this? How to connect? Which contact goes where? My head is spinning.)))

[RR1957]

Philips AG9018 amplifier. Three contacts for connecting acoustics. Three contacts on the speaker itself (AD 4690). How to assemble all this? How to connect? Which contact goes where? My head is spinning.)))

The speaker we see is NOT an AD3700AM.
This is:
http://www.hupse.eu/radio/speakers/AD3700.htm



A stands for 800ohm (B is 400ohm), M stands for double conus.
De AD3700 has two connections.
About the connection you can use 2 or 3 (both top on your photo) and 1 (a bit further away fom the other two) is earth.

Amp:
http://www.hupse.eu/radio/Philips_AG9018.htm
You can use it for 800ohm, 8 or 16 ohm.

Original for 800ohm these connectors were used, now still available in metal.

[Folter]

In my photo there is AD 4690 AM. I indicated this in my message. Do you think they will sing correctly with AD 3700 AM in one speaker? What will happen to the overall impedance when connected in parallel?

[RR1957]

In my photo there is AD 4690 AM. I indicated this in my message. Do you think they will sing correctly with AD 3700 AM in one speaker? What will happen to the overall impedance when connected in parallel?

You wrote you had a pair AD3700AM to use.
And you wanted to buy a pair more (succes, even in Holland rare).
And you did not mention the AM with the AD4690(AM). Rather important.
I was concentrating on your wish about the AD3700AM.
The 3700 is too poor for a good bass, for that you need the 9710A f.e.
Philips combined sometimes two OTL speakers to get 800 ohm, f.e.
two of 400ohm in series. I have used that several times but in mono combinations.
If you want two different 800ohm speakers in a cabinet you need a cross over filter.
Or you need a bi-ampli stereo amp, or two bi-ampli mono blocks and a pre-amp.
I wish you succes.

[analogadikt]

In my photo there is AD 4690 AM. I indicated this in my message. Do you think they will sing correctly with AD 3700 AM in one speaker? What will happen to the overall impedance when connected in parallel?

Are you sure it is AD4690AM ? The Philips datasheet does not mention such a driver. What you have appears to be AD4690M/800. This driver has a resonance frequency of 135 Hz so it is not suitable for bass frequencies. You have to install a high pass filter capacitor in series with the driver to protect it from low frequency signal.



In case of the 3 point connector, #2 is speaker + , #1 is ground or return and #3 is unused. Of the 3 terminals on the driver , two would be common and you have to use only one of them and the third one.
#2 is speaker+ , #1 is unused and # 3 return or ground






Click on the images to expand them

Regards,

Anwesh

[RR1957]

btw

[simon]

Just pay attention to the numbering :

[Folter]

Are you sure it is AD4690AM ? The Philips datasheet does not mention such a driver. What you have appears to be AD4690M/800. This driver has a resonance frequency of 135 Hz so it is not suitable for bass frequencies. You have to install a high pass filter capacitor in series with the driver to protect it from low frequency signal.
Regards,
Anwesh

Yes, this speaker is indeed labeled AD4690M/800. I just assumed that all 800 ohm full range speakers were labeled AM. This speaker is not mine. Photo from Ebay. I just wanted to pick up a pair of OTL speakers to go with the 3700AM.

[RR1957]

One could ask why there are TWO + connections (1 and 2) on the connectors of the 800ohm speakers and only one for the earth.
This had to do with earlier mono bi-ampli audio combinations. I had such combinations till January this year.
Connection 1 was for the high tones and 2 for the low tones, both seperately amplified. 3 was the earth combined for both.
On the speakers Philips made a bridge between 1 and 2, so there was no mistake possible. On the photo the back side of the
bass speaker connection. The gray cable is the earth.
The seperate high tone speakers were connected on a small connector in the bass speaker and a thick cable (so with three internal
cables: high tones, bass and earth) was between the bass speaker and amplifier.
Just explaining.

[Folter]

In case of the 3 point connector, #2 is speaker + , #1 is ground or return and #3 is unused. Of the 3 terminals on the driver , two would be common and you have to use only one of them and the third one.
#2 is speaker+ , #1 is unused and # 3 return or ground

I hope nothing will burn out if I make a mistake with the wiring?

[RR1957]

I hope nothing will burn out if I make a mistake with the wiring?

I suppose just the phase will be wrong.

[Folter]

One could ask why there are TWO + connections (1 and 2) on the connectors of the 800ohm speakers and only one for the earth.
This had to do with earlier mono bi-ampli audio combinations. I had such combinations till January this year.
Connection 1 was for the high tones and 2 for the low tones, both seperately amplified. 3 was the earth combined for both.
On the speakers Philips made a bridge between 1 and 2, so there was no mistake possible. On the photo the back side of the
bass speaker connection. The gray cable is the earth.
The seperate high tone speakers were connected on a small connector in the bass speaker and a thick cable (so with three internal
cables: high tones, bass and earth) was between the bass speaker and amplifier.
Just explaining.

There are more questions than answers. After all, AG9018 also amplifies high frequencies separately, and low frequencies separately? Therefore, all three contacts of each channel must be assigned?