[Sarchi]

No, you're right fran! B+ has to be the issue. I have my +24V going to J4 (instead of H+) and the negative to J5 instead of H-. How should I get the juice to B+?

--

I've redone C3/4, same result. I'm reversing the attenuator now...

 

[looser101]

Quote:

Originally Posted by Sarchi /img/forum/go_quote.gif OK..here are two pics of the breadboard, finally. Note that I have my power leads inverted as far as color-coding. I AM observing correct polarity. Also note, H- has two pads (vertically), one is hidden behing the red power lead. To answer dB's question...J5 does NOT connect to H+, as far as I can see. The pcb has two layers of traces, I hope the pics don't add to the confusion.

Not sure why you decided to change the wire colours to the heaters. Red should be +24 from the batteries and should go to J4 closest to H- and the black from battery (-) to J4 closest to J5. Also run the same +24, either from the heater +24 or a separate run from the battery, to B+. Do the same to battery (-) ; connect it to GND below J7. Shorting C3/C4 means to run a wire from one pad of C3 to the other pad of C3. Do both C3's and both C4's. Move the attenuator to input, output goes directly to amp.

~Renato

 

[dBel84]

I had looked for B+ earlier but when I couldn't see it , I assumed it was linked in series with the heaters. I was wrong. Fran solved this I think, B+ needs to be connected?

..dB

 

[looser101]

Quote:

Originally Posted by dBel84 /img/forum/go_quote.gif I had looked for B+ earlier but when I couldn't see it , I assumed it was linked in series with the heaters. I was wrong. Fran solved this I think, B+ needs to be connected? ..dB

Indeed, Fran solved it, he wasn't as tired as he thought. I just wanted it to be clear regarding connections and polarity, etc. The heater caps will be happier if the correct polarity is used

.

Btw - to measure the heater voltages just measure the voltage across the heater caps C7 to C10.

~Renato

 

[dBel84]

C7 and C10 need to be reversed for series operation..dB

 

[Sarchi]

Done.....and


[size=x-large]
SHE SINGS!!!![/size]



well, out of one channel, anyway.


Thank you so much, you guys are the best.

 

[dBel84]

very cool ..dB

 

[looser101]

Quote:

Originally Posted by Sarchi /img/forum/go_quote.gif Done.....and [size=x-large] SHE SINGS!!!![/size] well, out of one channel, anyway. Thank you so much, you guys are the best.

Sweet... we need impressions soon.

~R~

 

[Sarchi]

Hey Hey I've got Both Sides Now......

Pics at 11. Oops, it's 1130 already.


****, this sounds good. Really good! I've been listening to Mark Knopfler's latest quite a lot (on lousy 176k mp3's!) and I can now hear the 'gravel' in his voice. Seems like a nice improvement in detail. This is just on my desktop... Dell laptop->Aikido->Sophia Baby->B&W 201's (90dB 4 Ohms), and I JUST got the Sophia yesterday (replacing a t amp), so I can't vouch 100% for impressions...('til I get the amp/preamp downstairs into the main system)

I'm running the Baby pot wide open, btw. It's what you'd expect, things sound "thicker" (fuller) with the linestage in there.

 

[Sarchi]

It's playing music!!!!! (can you tell?)




Bit more detail.


Gratuitous shot of desktop. LOVE my new Baby amp...

 

[Sarchi]

I'm playing streams off Wilco's website now-- VERY familiar with these. This sounds excellent.

Some weirdnesses, before I forget them.....

1. I just couldn't get heater voltage readings off V3/4 (at the heater caps as Renato suggested). And that's the side of the board that worked first! But it wouldn't measure. V1/2 measured 13.8 and 7.05, I think. (I'm getting tired)

2. I also can't get a reading on my battery terminals, nor on J4, no matter what I try. Tempted to think my voltmeter's on the blink, but I really don't know.

3. Getting the other side to work was apparently just a matter of prodding with my voltmeter probe. Worked backwards from the outputs, C1, and bacl. Eventually I got to a resistor that didn't "buzz" when I tapped it (R1)..moved it a little, and presto. It should always be so easy.

4. Interconnects out of the Aikido. Apparently HAVE to be shielded. I tried my $5 Killer IC magnet wire ones and got a ton of noise - enough overwhelm the signal. So all the above impressions are with the 50-cent black patch cords that you get with your $19 DVD player. (for now) Not to mention my low end soundcard.



Again, many thanks for your help and patience reading this very convoluted thread. I will avow to bring my Aikido to a HF meetup sometime soon. (even tho it ain't a headphone amp)

 

[Sarchi]

Quote:

Originally Posted by kipman725 /img/forum/go_quote.gif Running any amp of battries is a bad idea. A regulated DC supply can have an output impediance (by using feedback) as low as 0.0001ohm wheras battries have output impedances of several ohm's at least. This means that the more current your amp is using at a point in time the lower the supply rails are. This means that the bigger drum hit or whatever you have the lower the supply rails sink which means that your sound will become load modulated. This is a bad thing as the amplifier will produce a more distorted output! if you used a large capacitor bank with the batteries this problem would be reduced... but the question has to be asked... whats the point?

In general I agree with your points, though I've had success running a Super T amp off an old car battery for the last year and a half. It works amazingly well. Never even needs charging.

The Aikido is a line amplifier (linestage preamp), it amplifies micro voltages. So the current demands should be pretty modest.

BTW, it drained my 1.3ah sla's in 2-3 hours. But, I've sold the T amp and also have another spare car battery, so the two will run the Aikido, for now. I might look at a regulated DC supply though. Hagerman has a nice one for the Bugle 12V...I'm not sure I'd want two of those though. Maybe something off the shelf like the Pyramid.

 

[dBel84]

Very good to hear that it sounds good to you, I would have expected nothing less based on past reports. If you buy an off the shelf supply, I would steer clear of switching supplies B+ and heaters ) try to keep the noise floor low. AMB's S11 would be the ultimate supply but you are on your own trouble shooting that one. ( it is really a straight forward build and mine powered up first time but it has an awfull lot of small parts and sensitive mosfets ) oh yeah, get new batteries for the DMM or junk it and get one that works

love the whole bread board idea

..dB

 

[fran]

For what its worth, there are linear power supplies available on ebay for about the $20-30 mark. Usually theres no prob getting one that will supply, say 2A. Thats what I bought for mine. They also normally have an adjustment pot - mine varies the voltage from about 21 to 28V. Its a great pity that there aren't 300VDC supplies similarly available as handy as that!

Fran

 

[fran]

Spurred on by this thread, I got mine mostly put together today. I'm using a relay based source selector from twistedpearaudio.com and I haven't got that put back together yet. But the tubes all lit up and there was no smoke - which is a good thing. The voltages vary just a little across the 4 tubes, say from 6 to 6.5V, so hopefully that'll be OK. If I get a run at it tomorrow night, I'll hook the rest up and finish out the casework. Photos and listening impressions to follow.

Just waiting for the dreaded hum to raise its head though....

Fran