PHILIPS EL3710 preamp info's needed.

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tubologic

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Mar 29, 2009
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I have many of these old PHILIPS EL3710 professional preamp modules but was unable to find any informations about them on the web. These are very well built units with massive transformers, nothing in common with the cheap crappy consumer products PHILIPS are know for. Looks like PHILIPS made professional quality gear too. These are very likely microphone preamps as you can tell by the Mic. symbol on the frontplate and 30/45dB indications on the back side. The 3 remaining switches are not labelled and I have no idea about their purpose. The tube complement is (1) E80F and (1) E80L and connections are via a 12 pin Tuchel connector. Unfortunately, unlike the V72's these preamps are not self powered and need an external power supply. Although building a power supply is not a problem, I'm wondering if it really worth the effort as nobody has ever heard this preamp and nothing can be found regarding their sonic qualities (or lack of). Also, I have no schematics and no idea about the required B+ supply. (should be around 300VDC, the 1st filter cap is rated at 500VDC).
Does anybody here has any experience with these modules, or better a copy of the schematic or manual ? Any informations about these old preamps would be greatly appreciated. Thank you for your help.
 

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Feedback like a Collins 356A/Langevin 5116.

tubologic said:
I'm wondering if it really worth the effort as nobody has ever heard this preamp and nothing can be found regarding their sonic qualities (or lack of).

Oh boy, so much stuff would go in the dumpster under that premise.
 
Philips did a lot of pro radio and tv equipment , they look like very nice preamps and would be  well worth making a dedicated psu for in my opinion.  Sometimes OD&D (outlaw recording and pa) have parts from old Philips consoles including psu's .
 
I have many of these old PHILIPS EL3710 professional preamp modules but was unable to find any informations about them on the web. These are very well built units with massive transformers, nothing in common with the cheap crappy consumer products PHILIPS are know for. Looks like PHILIPS made professional quality gear too. These are very likely microphone preamps as you can tell by the Mic. symbol on the frontplate and 30/45dB indications on the back side. The 3 remaining switches are not labelled and I have no idea about their purpose. The tube complement is (1) E80F and (1) E80L and connections are via a 12 pin Tuchel connector. Unfortunately, unlike the V72's these preamps are not self powered and need an external power supply. Although building a power supply is not a problem, I'm wondering if it really worth the effort as nobody has ever heard this preamp and nothing can be found regarding their sonic qualities (or lack of). Also, I have no schematics and no idea about the required B+ supply. (should be around 300VDC, the 1st filter cap is rated at 500VDC).
Does anybody here has any experience with these modules, or better a copy of the schematic or manual ? Any informations about these old preamps would be greatly appreciated. Thank you for your help.
Hi
Bought 35 years ago a vintage Philips mixer built by a danish engineer for the first multitrack studio based in Portugal from the 50/60. I just start this month to refurbish and restore at its original shape!!!
Looking for some info and help on this unique mixer
 

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It was quite common for Philips to commission freelance designers for building custom recording consoles in a collaborative work with their own reams. That's how the mixer at Polygram's Studio des Dames came to life. Most of the electronic design was based on Graham Cohen' work.
 
Dear Decada, I do have the diagrams of the Philips mic pre s. I can look them up, as soon as I am home next week. . So mail me if I forget...
Btw these bulky in/output trfrs are worth a lot of money these days! Like €150+ a piece...
Grzz Wim Bénard, the Netherlands
 
Looks like an amazing piece of kit , must have cost a kings ransom back in the good old days .
It seems to have an EQ section per channel , practically unheard of back in those days .
Philips Radiomuseum in Eindhoven might have some additional info on these consoles .

Look at the simplicity of the circuit , it isnt often Dougie gets that excited about vintage European gear .
 
What I dont understand about the EL3710 schematic is where does the E80L anode supply come from ,
 
Dear Decada, I do have the diagrams of the Philips mic pre s. I can look them up, as soon as I am home next week. . So mail me if I forget...
Btw these bulky in/output trfrs are worth a lot of money these days! Like €150+ a piece...
Grzz Wim Bénard, the Netherlands
Thanks Bénard!! Looking forward to have more info about this mixing console!
Regards Rui
 
Looks like an amazing piece of kit , must have cost a kings ransom back in the good old days .
It seems to have an EQ section per channel , practically unheard of back in those days .
Philips Radiomuseum in Eindhoven might have some additional info on these consoles .

Look at the simplicity of the circuit , it isnt often Dougie gets that excited about vintage European gear .
Hi
Will publish all restore process in order to let everybody follow!
Already contact the Philips Museum at Heindoven, waiting for their help
Regards Rui
 
Or possibly a fuse, as 63mA is a standard fuse value.
It could be two things: either a fuse, as you suggest, or just an indication of the module's current draw.
Hard to tell since the symbol is not a standard one.
My first reaction was the latter, but I can't guess what the Philips draftsman had smoked that day. :)
 
This is obviously a symbol for fuse because there is certainly no choke coil inside the module. I have somewhere schematic of the module I reverse engineered, I will publish it if I find it.

1648126200672.png

(The picture is taken from moonmusic.eu)
 
I didn't suggest it was a choke, for it would be a very strange symbol for it.
It is probably a fuse, because the current draw is spec'd at 14mA in the document.
It is certainly a very weird symbol for it.
There must have been something in the air or in the water in Eindhoven at the time...
 
There must have been something in the air or in the water in Eindhoven at the time...

For sure :). Interestingly, they used this symbol for a fuse in their "mini" tube amplifier EL6471 (1kW) in earlier versions

1648144653007.png


while in later versions they used the well-known and common symbol.

1648144684763.png

In the EL37xx series amplifier, they also used that symbol.

1648144714986.png

Edit:
I did a little more research and came to the conclusion that maybe at the time they used the symbol for circuit breaker instead of fuse, which is not so very wrong.

1648146002424.png
 
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