New project: Telefunken ELA V306 tube amp

[Hotzenplotz]

The speakers that connect to the 100v output should each have a transformer to step down the voltage to that suitable for the speaker, I believe. This is what you mean by a converter, correct?

Right.

I think that #9 and #10 are low level inputs, the symbol on those make me think of microphones; why would there be a left and right output (exit) when the amp is mono, plus, they would not have put outputs at that location?

Hmm, good point! So one of the reasons for posting was the question if this is mono. Seems to be!

In this case you should have no problem plugging your toaster equipped guitar into one of those, actually you could plug into any of the inputs, the volume may just be too low from the line inputs.

Yes, seems to be right! The complete right side is input.

If # 7 is a phonograph input there should be an equalization circuit like the RIAA type (more likely, a European equivalent) to flatten out the response of the pickup cartridge.

I have to ask for next week if there is something like that.

Now You confused me, but seems to be closer to what this amp is!
What does it mean for playability? This one must have much head room, right?

Can I use a compressor for raising the signal, with a view to achieve some smooth (smokey) british overdrive?


Aaah! Next thing: after Your post I had a close look to the round plug, sticking in that 100V slot. I thought it was something like a bridge. This Plug has got three contacts in a row. Turning the middle contact allows to open the plug. There are two screws for connecting the cables of some speakers! Strange, never see system! That is the output plug!!! You are absolutely right!

[Hotzenplotz]

Here pics from the plug:

1. closed
2. opened


O.K., and now I seem to know why there are three 12AX7 tubes in that amp. - One per input channel.

And the other two pairs are for output: two EL34 and two EF86 to allow 40 Watts, right so far?



PS: I start to hate my mobile phone...!

[jps]

Interesting speaker connection, however I am not real familiar with how distribution systems are set up; it may be a balanced system like an XLR balanced mic input in that two pins are the two sides (+/- )of the secondary on the output transformer of the amp with the middle pin (possibly) being the shield/ground connection, same as pins 1,2 and 3 of an XLR connector. Keep in mind, this is only a guess on my part.

Most likely the two EF 86 and two of the 12AX7 tubes are involved in the input /EQ circuitry with one of the 12AX&s for the phase inverter to split the mono preamsignal to the the two EL 34 output tubes in a standard class AB push/pull configuration.

Once your brother makes sure everything is working as is should or repair any issues, you could try a borrowed guitar first.

As to a compressor, that would work fine as long as the input of the amp is not being overloaded, although that may be exactly what you want depending on the tone/distortion you want to get out of the amp.

I am now thinking that the amp may easily be converted to a standard output; perhaps the output transformer is a normal output transformer and there is addition circuitry and/or another transformer inside the chassis to bring the output up to the nominal 100V?

[Hotzenplotz]

Interesting speaker connection, however I am not real familiar with how distribution systems are set up; it may be a balanced system like an XLR balanced mic input in that two pins are the two sides (+/- )of the secondary on the output transformer of the amp with the middle pin (possibly) being the shield/ground connection, same as pins 1,2 and 3 of an XLR connector. Keep in mind, this is only a guess on my part.

All guesses are welcome. And useful, as already seen before.

Once your brother makes sure everything is working as is should or repair any issues, you could try a borrowed guitar first.

Not a bad idea! But trying to be kind I use my own very first guitar. That is a non collection thing, even if, the pickups are very lousy. A necessary exchange of them would as a worst case scenario not be the end of the world. - Much better than to fry my holy toasters.

As to a compressor, that would work fine as long as the input of the amp is not being overloaded, although that may be exactly what you want depending on the tone/distortion you want to get out of the amp.

One more thing I seem to understand from Your postings - please correct me, if I am wrong.
There are two different kinds of inputs:
1. Those, that work with a "self-producing signal" (that term is surly not right, but explains what I mean): a tape, record player, CD player etc. offer these. They really send some signal.
2. Those, that work without sending an own signal, for example microphones without a source of electricity - and guitars. They just influence an incoming signal.
Right?

That would mean, plugged into e.g. no. 9 or 10 (input for not "self-sending devices") combined with a compressor or other output level raising effect stomp, will deliver some slight overdrive, because the preamp has a constant rate of amplification, caused by the tubes. More incoming signal to the tubes will result some saturation, the tube will go into some overdrive.
If this is right, I will receive exactly what I am looking for. For a real rough distortion (what I never use) I can use a stomp box like a tube screamer. I love the sound of the "Brown Sugar" intro from the stones. That is my style!!!

I am now thinking that the amp may easily be converted to a standard output; perhaps the output transformer is a normal output transformer and there is addition circuitry and/or another transformer inside the chassis to bring the output up to the nominal 100V?

Yes, seems to be this way! Compare with the pics, there are two transformers, a small and a big one. The small one could be that 100 volts transmitter thing.
Well, there is one free slot (no.2) as already mentioned. I can use that for connecting with "normal" speakers. As I know the big transformer has got several output connections. To connect the right one to the free slot - that could be the right way. I just have to know which impedance this way delivers.


Thank You for helping! I am sorry, maybe some things written from me sound a bit confused. But it is not easy to read and write all these technical things in a foreign language.

[fatcat]

The speakers that connect to the 100v output should each have a transformer to step down the voltage to that suitable for the speaker, I believe. This is what you mean by a converter, correct?

I think that #9 and #10 are low level inputs, the symbol on those make me think of microphones; why would there be a left and right output (exit) when the amp is mono, plus, they would not have put outputs at that location? In this case you should have no problem plugging your toaster equipped guitar into one of those, actually you could plug into any of the inputs, the volume may just be too low from the line inputs.

If # 7 is a phonograph input there should be an equalization circuit like the RIAA type (more likely, a European equivalent) to flatten out the response of the pickup cartridge.

Jeff's right, it is a paging/p a amplifier whith high impedance output, to allow for longer wire runs .Minimize losses due to resistance(see ohm's law).
Each speaker will have a stepdown transformer attached to convert the signal to a useable level.Many times, they will have a balance pot as well.
Further readinghas more details.

Bottom line: low impedance speakers won't work,connected directly.



Edit: the 2 volt tap might work for low impedance speakers.

[Hotzenplotz]

Thank You for the very informative link! So I will read this a few times to understand it completely right.

What is the voltage of "normal" speakers? I can not imagine just 2V. But if, it would be perfect! Then it could be ran with two systems without changing the wiring.

[jps]

The 2V connector can't be a speaker out, the voltage is too low for any real useful volume, if that is what it is. Your brother should be able to figure out what all the connectors really do, at the moment we are making guesses that could have a damaging affect on things!

The microphone and phonograph inputs are designed for very low voltage input devices, and their preamp stages are high gain stages to bring the tiny signals up to that matching the line level sources to feed the power amp with an adequate signal level.

The two transformers are the power supply (larger one) and the output transformer (smaller one). I am only guessing above as to how a distribution amp works, I have not read up on how the output signal is derived.

[Hotzenplotz]

The 2V connector can't be a speaker out, the voltage is too low for any real useful volume, if that is what it is. Your brother should be able to figure out what all the connectors really do, at the moment we are making guesses that could have a damaging affect on things!

I agree!

The microphone and phonograph inputs are designed for very low voltage input devices, and their preamp stages are high gain stages to bring the tiny signals up to that matching the line level sources to feed the power amp with an adequate signal level.

We will know exactly on, I think, tuesday.

The two transformers are the power supply (larger one) and the output transformer (smaller one). I am only guessing above as to how a distribution amp works, I have not read up on how the output signal is derived.

Same on tuesday, too.

Great, how this forum is working! There are people all around the wold, very kind, and we work out the things of our interest, even how to use things other people have thrown away.
BTW the way HOW this is happening, without the "normal" rough tone of conversation of other forums I know, is a further plus!
Great people here!
Thank You all!

[jps]

BTW the way HOW this is happening, without the "normal" rough tone of conversation of other forums I know, is a further plus!
Great people here!
Thank You all!

This is one of the best things about this forum, besides of course, the subjects of our interest, here. The people on this forum are the best, and I can say that from truly personal experience.

Exhibit A, MARF III:

Group_1200_6517.jpg

RRF members from around the world!

[Hotzenplotz]

Damn, I live on the wrong continent!

In former times I lived in Brazil - America, too, but south.

But an idea is, to fly to the US, pick a Rickenbacker there and share some time with RRF members.

[jps]

Damn, I live on the wrong continent!

In former times I lived in Brazil - America, too, but south.

But an idea is, to fly to the US, pick a Rickenbacker there and share some time with RRF members.

That's been done on occasion with members. Some of our Australian members has lots of experience with that, I think.

[Hotzenplotz]

Funny, last weak I was talking about as a dream.

Well, I'll have to work on it.

Btw. I could really imagine to settle down in the States...