6AN8 one tube se amp?

[ALBATROS1234]

i was thinking now that i got my 1st 2 amps working well i wanted to try and build a low wattage one tube amp ,i have a bunch of xfrmrs to use with a standard bridge recti/ filter cap ps to run a one tube amp. i noticed the 6AN8 is a triode and a pentode. i read that the triode is 1/2 of a 12ax7 and the pentode is a 2.5 watt max plate dissipation tube stage. well the wheels started spinning. i figure it wouldnt be a super great sounding amp but i want to try and make a quicky low volume guitar amp in a small package . just a cute little box with one bottle sticking out the top one knob with an input and output. i have a small ot from a 1950s radio . could use an od pedal for breakup. is there any reason why i cant play around with this?

[DummyLoad]

triode section of 6AN8 is closer to 12AU7 than 12AX7.


6DX8 triode is similar to 12AT7.
6CH8 triode is similar to 12AX7.
6GN8 triode is similar to 12BZ7 (12AX7 on steroids) also with 5W pentode.
6JA8 trode is unique - medium mu (AF= 60) also with a 5W pentode.
6U8 triode is also medium mu (AF=40) but with 3W pentode.
6AW8 triode is high mu (AF=70) with 3.75W pentode.
6DZ8 triode is high mu (AF=100) with 6.5W pentode, also very, very rare.
6HF8 triode is high mu (AF-70) with 5W pentode.
6HC8 triode is high mu (AF=68) with 11W pentode, also very, very rare.


--pete

[kagliostro]

Copy something like a 5F2-A

use the 6AN8 triode as V2 and as V1 a jfet or mosfet

give a look here



and



http://www.hawestv.com/amp_projects/amp_solid_tube/fetpreamp_200v1.htm

Franco

[ALBATROS1234]

thanks guys, i saw that there are tubes with more powerful pentodes but,1 i have a 6AN8 already and i am not concerned with making something very powerful. thinking of mounting the circuit in the chassis of a busted 1950s rca radio using the 3"speaker which is already in it.

so kagliostro youre suggestion i can do it but i should add a transistor in position 1 then go into the triode followed by the pentode. is the advantage just more gain or is it a tone thing. or in using the transistor to create overdrive similar to a overdrive pedal?

[kagliostro]

Is a mix of the two things, also if not very strong

consider that a lot of LoFi amps has a single triode and a power tube but that guitar amps that uses triode on the preamp in most cases use two triodes one following the other

one other thing to be considered is that the triode of the 6AN8 has a gain that is lower than the "standard" 100 of a 12ax7 tube (and as we know the 12ax7 is the most used tube in guitar preamps)




One thing for which I haven't an answer is which will be the "right" OT load for the pentode section of the 6AN8 tube as to use it as Power Tube

EDIT: Because of the low gain of the 6AN8 triode, it will be better to copy 5F1 schematic instead of 5F2-A (Tone Control eat gain)

If you want to use a Tone Contro the transistor must be followed by a Souce Follower (Cathode Follower using a mosfet), this will avoid loss of gain and perform a better drive of the triode also if a Tone Control is installed)

Franco

[PRR]

> I haven't an answer is which will be the "right" OT load

In the neighborhood of V/I.

That data-pic shows 200V 9.5mA, which is 21K. The Fender Reverb transformer is cited as 15K or 25K; unsure, but either is as close as it needs to be.

If we wanted "a monster", we would carefully optimize for best blasting. However I think '1234 just wants 'sound', not a specific club-filling size.

The pentode side will need around 2V peak drive for full output. If the triode is AU7-like it has gain of 15-17. This works out to 100mV peak or 70mVrms at guitar jack, rather high by modern standards. A boost-pedal may be nice to have.

[ALBATROS1234]

yeah, this is just an experiment, wasnt planning on it going anywhere. i am fiddling to learn how differnt things behave in different circumstances. for instance today i built a 12BA6/12AQ5  amp. it was a fail.just a 1meg volume pot at the input them jumped tube to tube to ot. dont think i was biasing the preamp tube right, it was rather low in volume and quite anorexic sounding even though i had sufficient voltage and current. got some stuff coming in the mail anyday gonna play with a 12ax7/el84 shortly. i rather like the tone of my last project with the 12SL7/12AQ5 situation but it seems odd with a 7 pin mini power tube and an octal preamp