Poll..anyone interested in an Aikido linestage PCB group buy?

Andypairo · 2009-01-12 10:04 am

Brit01 said:
Thanks Bas. That's pretty straight forward.

If the Aikido has too much gain and I want to lower this without changing the input tubes (currently running 6N1P with 5687), what would be the best way?

Thanks

You can also use a step-down transformer at the output.
I ended up using the Aikido as front-end for a hybrid amp, followed by a power diamond buffer.
Steve Dunlap's "Krill" would be a great candidate for such use.

Ciao

Andrea

Brit01 · 2009-01-12 10:12 am

Maybe I'll search for some new tubes with a lower mu and experiment with those first to get the required gain for my power amp. I thought it would be easier.

Is the 6H30 recommended? This has a mu of just 15. Half of the 6N1P.

If that fails then I'll try these suggestions.

I've also been reading a lot of threads regarding the Hybrids. The Moskido looks interesting.
I think my next project will be a point to point Aikido and Mosfet or even 300B/Kt88 power end.
So many great ideas on this forum that have me totally hooked.

There are great deals on ebay. I just got 24 Wima caps for just 5 USD including postage. Some 0.47 uF and 0.22uF values.

Bas Horneman · 2009-01-12 10:24 am

Yes, The 6h30 is recommended. Or the 6N6P.

Brit01 · 2009-01-12 11:57 am

Looks like the 6H30 is a bit pricey and hard to find.

I see there are great deals with the 6N6P but it has just a slighty higher gain.

Might order some 6N6P's.

Liliya · 2009-01-12 4:24 pm

6N&P

Brit 01

I have built a Aikido line stage with 6N6P in both position. I am very pleased with the result. I learn to know this tube from Lukasz Fiskus Lampizator analog stage for DAC.

Recommended!!

Now I am building a headphone amplifier with the same tubes in both position for my AKG K-530. I use the "beautiful" PCB from JB and powerunit from Bas.

Eivind Stillingen

Brit01 · 2009-01-12 4:40 pm

Thanks Eivind for the recommendation.

Yes the JB board is beautiful I have to agree. I also have the Bas psu (from Gregg in Canada).

I want to start trying to point to point now. (mainly due to the importation laws here in Uruguay as I can't buy much stuff from USA).

If a friend is coming from USA then I take advantage.

I'm really interested in experimenting with new designs also. It's a shame that I don't have a local shop where I can just pop down and buy whatever I need, valves, sockets, transformers etc.

That would be so great.

Brit01 · 2009-01-12 6:10 pm

Calculate it. I.e. measure the voltage across the cathode resistor. R=V/I So if you need I I=V/R V=what you just measured...say 3,5V R=value of the resistor say 1000 ohm = 0,0035A times 1000 to get mA. 3,5mA is running through the plate.

Results:
Right Channel:

R2 = 3.36 mA
R11 = 10.55 mA

Left Channel:

R2= 4.0 mA
R11= 11.02 mA

Are these differences in acceptable range?

Bas Horneman · 2009-01-12 6:55 pm

That is acceptable. 10-15% is normal.

I can't really comment on matching because there are other parameters involved and I'm not too savy on them.

Brit01 · 2009-01-16 3:47 pm

Hi Bas,

Is that 5W resistor (R1 I think) meant to get so damn hot? There is no sign of burning. I guess it is designed to take heat.

Should I change this for a 7W or 10W?

Cheers

Brit01 · 2009-01-21 8:19 am

While still on the breadboard I hooked up a very cheap logarithmic stereo volume pot and I'm getting a horrible hissing noise coming through. Amplified when I hover my hand over the signal wire on the connecting side after the pot.

I tried some shielded microphone wire but still the hissing noise.

Any ideas? Is this due to the nasty volume pot or just a grounding problem?

Please help.

Bas Horneman · 2009-01-21 8:51 am

Is that 5W resistor (R1 I think) meant to get so damn hot? There is no sign of burning. I guess it is designed to take heat.

Should I change this for a 7W or 10W?

Cheers

Calculate how much work it is doing.

P=I*I*R

In other words if there is 50mA running through it.

0,05A*0,05A*1000 ohm=2,5 Watts

5 Watts would be sufficient. But some overrate their resistors: Europeans by a factor of 2, Americans by a factor of 5

So there is no harm in changing this to a 7, 10 or even 50 Watts. It does not hurt...it only hurts your wallet.

Bas Horneman · 2009-01-21 9:00 am

horrible hissing noise coming through

This is hardest to fix without experience. So trial and error is your friend here. Try googling how to ground your amp.

Is the microphone wire screened? On which side did you ground the screen?

What does your grounding scheme look like?

Brit01 · 2009-01-21 9:31 am

Is the microphone wire screened? On which side did you ground the screen?

wire is screened.

I have the RCA shields connected to the stereo pot ground points, then these are connected to the signal in ground connections on JB's board.

The ground from the psu is connected to the main ground point on JB's board.

I have not connected the star ground point on the JB board to any point yet. I will connect this to a thick copper bar tonight.

I was under the impression that grounding problems normally cause a lower freqency hum noise rather than a hissing static like sound.

0,05A*0,05A*1000 ohm=2,5 Watts

In theory looks like this is fine then. As there are no signs are burning I'll leave it as it is. It's a good quality resistor from tubesandmore.com.

Cheers

Bas Horneman · 2009-01-21 9:44 am

I was under the impression that grounding problems normally cause a lower freqency hum noise rather than a hissing static like sound.

Generally true I think.

I have the RCA shields connected to the stereo pot ground points, then these are connected to the signal in ground connections on JB's board.

Try disconnecting the shield on the RCA side. So that the screen is only grounded at one point.

Brit01 · 2009-01-21 9:51 am

Try disconnecting the shield on the RCA side. So that the screen is only grounded at one point.

When you said screened did you mean shielded?

The shielded microphone wire has 2 wires, which I'm using for left and right signal. I have 2 other wires for the grounds, going from the shield on the RCA to the pot and then to the ground on JB board.

EternaLightWith · 2009-02-08 7:27 am

I know it's 3 years later, but are there any PCBs left?

David

Brit01 · 2009-02-08 1:11 pm

I know it's 3 years later, but are there any PCBs left?

Try contacting Geek (Gregg). He has a shop up in Canada. He may have some boards.

Geek · 2009-02-08 11:39 pm

Power PCB's? Yup! A few left

Cheers!

billywandell · 2009-03-03 3:46 am

Aikido Power supply for Aikido 6CG7 - 5687 by Mr. Bas

Hello, I am going to attempt to re purpose a Lafayette mono amp, and turn it into an all point to point wired Aikido 6CG7 - 5687 line stage - Using the PSU V 1.0 schematic by Mr. Bas from this site. I have studied this site and thanks for all info so far. The transformer I want to use is 280V - 0 - 280V / 110ma. I am a little confused between what is marked on the transformers, vs what is marked on the schematics. In Bas' schematic would his transformer be marked 125V - 0 - 125V / 50 ma. If yes, can I use my transformer if I connect only one of the 280V leads to only on of the 6X5 tube plate pins ? Would that give me properly rectified 280V, at one half of the rated ma; 55 ma ? Thanks in advance for setting me straight, I will have maybe 4 more questions after this one. Steve

Brit01 · 2009-10-28 11:27 am

Regarding Gregg's psu:

2 times now one of the 2 parallel diodes on the psu has malfunctioned (blown) resulting in my power transformer almost melting. 1N4007 I think I am using. at the office now so can't confirm but I'm using the common recommended ones.

Not driving anything hard (one triode buffer) and within good limits tested with Duncans PSUII.

Has anyone else had the same problem?

I intend to use a higher rating diode now.

Poll..anyone interested in an Aikido linestage PCB group buy?

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