Need Help Identifying these TUBES
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gsferrari

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Please download the pics from here :-

[EDIT] I have posted the links below [/EDIT]

I want to know a little bit about the tubes and what I can do with them. These tubes are from a Grundig Spool Player amplifier section and they all work. I was using the signal tube that came with this spool player in my MG Head amplifier and although the gain was a little low, it worked and sounded great!!

There are a few other tubes from the spool player and I will put those pics up as well...until then PLEASE give me some feedback. I would love to use these tubes and build a headphone amplifier. The amplifier on the Grundig was driving two efficient speakers so I am assuming it will drive the Grados and Senns too...

um...I am hoping


Waiting for your feedback!!
 
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gpalmer

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I get a 530 Login incorrect error when I click on the link...
 
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ServinginEcuador

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It wouldn't let me onto your site. It is asking for a username and password.
 
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gsferrari

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The names of the tubes are pretty obvious...what I dont know is the "function" of these tubes...

If someone can just describe what these tubes are good at and how they are used it will be great!!

The TESLA doesnt work in the MG Head (I can barely hear anything with the volume turned up completely) but the Telefunken EC-81 works very well and sounds awesome!!


Does anybody know how much these tubes are worth?

Can anyone suggest an amplifier design based on these tubes for a Headphone amplifier application??

Thank you VERY much for your time people!!
 
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Tuberoller

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I'M stumped.

I'll check all my books and ask my Dad to take a look at them and attempt to respond with some helpful info.
 
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gsferrari

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I must say these are rather old tubes...

The Grundig Player they came from was a 1960 something model...

I'll try to find the exact model online and update this thread...
 
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ServinginEcuador

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The El42 is an Audio Frequency pre amp tube. Eight pins, and a mu of 288 according to Duncan's tube program.
 
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braillediver

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The first one could be a Magic Eye Tube because of the shape.

The Telsa no idea.

The Last one the Telefunken looks like a ECC81 or 12AT7.

You shouldn't be haphazardly plugging tubes into the amp.

The ECC81 / 12AT7 is close enough to use in the MG Head.


Mitch
 
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gsferrari

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Only the EC-81 and the TESLA (dunno which model) fit.

They looked like signal tubes (like so many tubes from the 12AX7 and 5751 that I have scattered here) so I plugged em in. The others stayed far away...

I thought the POWER tubes were the ones to worry about...I didnt know the signal tubes would cause too much of a problem...but I am naieve about these things...should have asked


The EC-81 Telefunken worked very nicely in the MG Head...
 
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gsferrari

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Quote:

Originally posted by ServinginEcuador
The El42 is an Audio Frequency pre amp tube. Eight pins, and a mu of 288 according to Duncan's tube program.


It is the pre amp tube. What is "mu of 288" ?? Sorry for being a tube n00b


Which tube out of this lot is a power tube? The grunding was a 100% valve based unit so I am guessing a pair of tubes should have been power tubes. Are the EL42's power tubes??

What is the Tesla?

Thank you all for your responses...
 
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ServinginEcuador

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I wouldn't use the EL81 in the EL84 slot. Here's why:

Pinouts are different.

EL81

1. not used
2. grid 1
3. don't know what K means
4&5 heater
6. not used
7. not used
8 grid 2
9. grid 3


EL84 pinout

1. not used
2. grid 1
3. K and grid 3
4&5 heater
6. not used
7. anode
8. not used
9. grid 2

Seems a couple of items aren't the same, and these tubes, while retaining the same number of pins, doesn't necessitate that it is a direct replacement. In this case I would say the low gain is due to the fact that something is going where it shouldn't therefore could cause problems with the amp.
 
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gsferrari

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Doug,

The only tubes I tried to use were the Telefunken EL-81's in place of the 12AX7 and 5751 in the MG Head (Signal Tubes). I also tried the Tesla Whatsit in the same Signal Tube socket without success...

I havent attempted to use the other tubes with this amp.

Now - what are the pre-amp tubes? Are they power tubes like the EL-84 (since the pin configuration is not the same - are they at least "functionally" similar? )

What is the Tesla Tube that I made pics of? Would you like pics from some other angle that will help you better??

Also - the curious looking tube - what the heck is that all about
 
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