• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

ECC808 what to do

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Yves wrote the important stuff already.

Might be interesting to sell them on Ebay, at least over here in Germany they give very good prices since they have been used in several commercial Klein & Hummel brand amps, lots of them still in use.

They are so scarce that Klein & Hummel gear often gets rewired to use ECC83/12AX7 instead.

Tom
 
Yes, I did find data sheet , and I thought to use it as an replacement in my EAR-834P phono preamp (revireing required unfortunatly). But I wanted to try them in some preamp design. Didn`t found any shematic. Dusan Klimo used those tubes in his preamp I heard. Only stuf I found was this.

Thanks for info.

P.S.
What kind of prices does this tube achive on the market?
 

Attachments

  • ecc808 preamp small.jpg
    ecc808 preamp small.jpg
    90.8 KB · Views: 856
They were used extensively by Rogers for many of their integrated amps and preamps so a search on Rogers might be worth while. These tubes were pretty unique in that they have a mu of 150 and so there simply is'nt anything that can be substituted for them (well not easily). They were often used in phono preamps with active RIAA for that reason. This means that once your current set of tubes wear out there is really nothing to use in their place

When I was searching for some, for a Rogers Cadet III restoration 3 years ago I found that they were "rare as rocking horse manure" and worth a LOT of money. I eventually tracked down 3 ONLY in the UK and paid 20 UK pounds each for them.

For a new design, may I suggest that you sell the ECC808 to restorers of vintage equipment and thereby raise cash enough to buy parts which WILL still be available in 5 to 10 years. It is my view that this would be doing yourself and others (who are desparate for ECC808 for restoration jobs) a favour.

The little "stashes" of ECC808 like your own are all the ECC808 that are still available, anywhere.

I know EC8010 was doing a Rogers restoration recently and he would echo my sentiments.

Regardless of above, they are your tubes and they ARE something special so feel free to disregard this advise.

Cheers,
Ian
 
they have a mu of 150 and so there simply is'nt anything that can be substituted for them (well not easily)

Really? The data sheet above says mu=100, gm=1.6mA/V at 1.2mA. Sounds pretty close to a 12AX7 to me! Clearly, these are not the same tubes, but with minor accommodations to pin out and heater supply, a 12AX7 and an ECC808 could probably be reasonable substitutes for one another. What am I missing?

But I agree with the advice to sell them and use the proceeds to buy mainstream tubes, and then to take the wife out to a nice dinner on what’s left over.
 
Brian,
You are correct - the Telefunken data sheet does say mu of 100. The Brimar datasheet however does say mu of 150. So designs using the Telefunken tubes could be converted to 12AX7 with a socket rewire as you say. Some of the Rogers stuff may be more problematical as they would have used Brimar tubes for sure.
Cheers,
Ian
 
Gingertube what you are talking about is the ECC807, not ECC808. The ECC808 is a low-noise version of the ECC83, but with a different pin-out ; the ECC807 is a different beast with its own characteristics (a mu of 150, as you say) and very hard to find. Brimar did make it and also called it the 13D7.
 
diyAudio Senior Member
Joined 2002
Hi,

I've got 6 of them (slightly used) and what to do with'em ??

You could use them as cascaded error amps in regulated voltage supplies as I did.....'Till smeone decided to buy up the already dwindling stock that is.

As for the ECC808? Just the best ECC83 variant ever made. Period.
Build a decent phono stage with them, they're entirely symmetrical in build and low-noise.

Ciao, ;)
 
Thank`s for the shematic . I supouse that the second stage of this phono preamp useing ecc808 is a gain stage which can be used as a stand alone line preamp section? No? Do you think that tube rectifier PS useing 2x280V transf. - AZ1 tube - CRCRC filter section would be suetable for this kind of design, or it will demand kind of regulation circuit?
 
diyAudio Senior Member
Joined 2002
Hi,

@Coffin: in your previous post you state that the preamp is regulated. I don't remember that. AFAIK it was just a well filtered CRC B+ supply using Roederstein caps.
The heater supply was regulated using a chip, LM317 or a 75xx, not sure.

Have you built one?

Cheers, ;)
 
Hi,

@Coffin: in your previous post you state that the preamp is regulated. I don't remember that. AFAIK it was just a well filtered CRC B+ supply using Roederstein caps.
The heater supply was regulated using a chip, LM317 or a 75xx, not sure.

Have you built one?

Cheers, ;)


check this:
An externally hosted image should be here but it was not working when we last tested it.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.