Akai M8

[Digital Man]

Hi All, A few months ago now, I purchased a Akai M8 reel to reel machine, it uses the EL84 tubes, I am just wanting to know what type of triode tube I could use In it’s place, I am thinking of either building it into two separate monos or probably a dual mono setup. Thanks 

[aussievintage]

Here's mine.   I wouldn't replace the EL84.  I'd just add a triode-wired option to it's circuit.  It sounds good, as it comes originally anyway.

 

Story here  

 

 

 

 

 

 

 

[ENIGMA]

I Agree with AV - don't replace the EL84 as it was originally a tube made for audio amplification and also that the circuit you are using was designed for it.

 

Its a very nice tube - I have them myself in my AZ Soundsales amps on my horns.

[xlr8or]

I'm with @aussievintage and @ENIGMA. The EL84 should be left untouched and is what the M8's are all about. There are plenty to be found both vintage and new production types. Do you have any photos of the tubes in there ATM?

Edited January 3, 2024 by xlr8or

[muon*]

I agree with others, stick with the EL84, find some NOS Philips/Mullard EL84's when budget permits.

[aussievintage]

2 hours ago, muon* said:

I agree with others, stick with the EL84, find some NOS Philips/Mullard EL84's when budget permits.

otoh  i like the original NECs mine came with

[Digital Man]

I haven’t checked inside as of yet, I plan to take it soon to my valve tech guy, we will then have a discussion 

[Digital Man]

Having said that, I would still like to know what Triode one could use, if one wanted to, not necessarily will do

[aussievintage]

1 minute ago, Digital Man said:

Having said that, I would still like to know what Triode one could use, if one wanted to, not necessarily will do

 

What's wrong with an EL84 in triode mode?  

 

The problem is, by the time they were using small sockets, most output/power valves were tetrode/pentode.

[xlr8or]

1 hour ago, Digital Man said:

Having said that, I would still like to know what Triode one could use, if one wanted to, not necessarily will do

 

The 6P1 can be used but it's extremely limited for noval 9-pin substitute options as only Russian and Chinese tubes were manufactured.

 

I would stick with the EL84 as there is far more variety available, including substitute options. You can't beat the musicality of the EL84 in comparison.

Edited January 3, 2024 by xlr8or

[Digital Man]

Hi, I never said that there was a problem with the EL84,

I just wanted to know what Triode could be used, if one desired so,

let me explain a bit more, I intend to completely gut these amps out,

use existing hardware and start with a whole new circuit design for

audio use, going to a triode maybe an option, if not. then I will stick

with the EL84's

[Digital Man]

Is the 6P1P a drop in replacement and upgrade to the 6P1 ? and

is both the 6P1 and the 6P1P also a drop in replacement as well

for the  6V6 types ?

[xlr8or]

33 minutes ago, Digital Man said:

Is the 6P1P a drop in replacement and upgrade to the 6P1 ?

 

A replacement tube, yes, but not an upgrade tube. Older generation 6P1 's sound much better than later generation 6P1P-EV's for example.

 

35 minutes ago, Digital Man said:

and

is both the 6P1 and the 6P1P also a drop in replacement as well

for the  6V6 types ?

 

Yes, with the only difference being the octal tube socket base required for the 6V6's.

[Digital Man]

interesting as I also have a se 6v6gt project nearing completion as well

[aussievintage]

1 hour ago, Digital Man said:

I intend to completely gut these amps out,

use existing hardware and start with a whole new circuit design for

audio use, going to a triode maybe an option, if not. then I will stick

with the EL84's

 

 

It would be such a shame to do that to a great existing design.  

 

These other tubes, 6P1/6V6  aren't triodes either.

[xlr8or]

Are you going to leave the 6X4 tube rectifiers in place or are you thinking of gutting that part of the circuit out and replacing it with s/s diodes?

[Digital Man]

I know that the 6v6 isn't a triode, keeping

it all valve, including the rectifiers

[doogie44]

In case it's useful? My Dad's original Akai M8 had these:

 

Valve complement: 2 x EF86, 2 x 12AX7, 2 x 6BQ5, 2 x 6X4, 1 x 6AR5

[Digital Man]

Hi, Thanks for that, in answer to everyone’s response, I will be using the EL84 tubes as well as keeping the valve rectifier as opposed to SS. I opened it up for the first time yesterday and all the tubes are gone, my tech guy has a full compliment of the tubes needed, he will install them to test the units to make sure that they are fully functional, once that is confirmed I will then set about buying replacement tubes for them.