What to build w/ Akai parts?

[Tube_Dude]

to eliminate RV1 (1M log),

No...change RV1 for a 100K log pot...this is the volume control pot!
And conect the wiper (midle pin) to the grid of the input valve...

eliminate RV7 (500k log)

Yes!...put a 470 K resistor in this place!

replace RV2 with a 100k log pot.

No ...delete RV2 and C1....if you don´t need tone controls...

Regards.

PS: pay atention at charged capacitors and high voltage...sorry but i don´t know your knowledge...

Sorry i forgot...the tone control is RV2...and yes is the circuit in shiFtYs schematic link!

[amt]

Thanks for the spoon feeding Dude,

Okay so I changed the schematic to what you suggested, I believe. Check this out.

amt

[Tube_Dude]

Fine!!!!! only RV7 need to be a 470k...not a pot...less noise!

Go to it!!!

[amt]

Does the wire between the tube still remain in place and if so, which side of the resistor does it connect?

(last question I think?)

thanks amt

[Tube_Dude]

Does the wire between the tube still remain in place

Yes i think that you talk about the conection betwen the resistor and the output tube grid...

which side of the resistor does it connect?

The side of the resistor oposite to ground... where the resistor conect to C3...

(last question I think?)

Fell free to ask...i hope that i know how to answer...heheheheh



Be my guest... motorcycle friend

[SHiFTY]

Also one thing I found is that the negative feedback resistor (R9) is quite variable: you can leave it out all together if you wish. I found around 10K sounded good (a tiny amount). You can play around here- but don't go too low (I didn't go below 5K)

The Akai output transformers have only the 8ohm winding for speakers, so you have to take it from there. (Many other transformers have taps for 4, 8, 16 ohm)

Also another tip- when you first fire it up, use the crappy akai speakers for testing purposes, in case you have made a mistake.

Oh, and also never run a valve amp without speakers Fireworks result.

Make sure you keep us posted!

[bournville]

Originally posted by ShiFtY
Also one thing I found is that the negative feedback resistor (R9) is quite variable: you can leave it out all together if you wish. I found around 10K sounded good (a tiny amount). You can play around here- but don't go too low (I didn't go below 5K)

The Akai output transformers have only the 8ohm winding for speakers, so you have to take it from there.

The original Mullard had a feedback resistor of 3.3k from a 4 ohm winding, so from 8 ohm output it should be 6.6k to keep the original 6db feedback ratio, but if gain is not a problem you could probably reduce this resistor to well below 5k.

[planet10]

I have 2 Roberts branded 6BM8 R-R amps. The 2 12AT7s are part of the pre-amp circuit and aren't required.

I also have a little Calrad 6BM8 SE... it is quite a nice little amp (even stock and in need of attention).

The circuit posted was the one i was going to leverage for my units -- the designer is no slouch. The Japanese are quite enamoured of the 6BM8 -- you can probably find some more references.

dave

[bournville]

Originally posted by planet10
The Japanese are quite enamoured of the 6BM8 -- you can probably find some more references.

dave

The 6BM8/ECL82 was quite popular here in the UK as well, especially for portable grams in the early 1960s. They are still used today - this link shows a pdf of a kit amp which looks loosely based on the Mullard stereo 7w per channel design, but without the 1/2 ECC83 for each channel.

http://www.worldaudiodesign2.co.uk/pdf/kecl82.pdf