[Tilpo]

The longest β22 build ever.

I started brainstorming and ordering parts on the 5th of October, 2011. I think I'll call that the 'official' starting date of this eternal project.
As of today 10 months and 23 days have passed since I started this project, yet I honestly doubt I'll be able to finish it any time soon. I hope to get it working within a month, which might be possible if I'm lucky.

After that I still want to get a power button with a relay, because the switch on the transformer box is far from practical. And on top of that, it just looks cooler to have a LED backlit button.

I also would love to get the LCD-uno, and get it remote controlled. And finally, I want to build an all-in-one package with an ODAC (or other DAC) sitting in the same case.
Chances are I also want to put the power supply entirely in a different case, instead of just the transformer.


The history of this project

6th of October: I wrote this blog post. (most of the images won't show up, for some odd reason)I decided to order all the components from Glass Jar Audio, for simplicity. I wanted to order the case from THL audio because they were pretty and relatively affordable.

19th of October: I paid for the components from Glass Jar Audio

31st of October: the parts were dispatched to me.

1st of November: I made a payment to THL audio. It took this long because their customer service through email is ridiculously slow. It usually took a week for them to respond.

4th of November: the case was dispatched to me.

26th of November: I received the components from Glass Jar Audio. The case arrived some two weeks before this, but I don't have an exact date.

29th of November: I noticed that I received a kit with mixed up resistors and a missing volume pot. I contacted Glass Jar Audio and he sent me the missing parts on the...

7th of December: Glass Jar Audio sent me the missing parts. At this point I had most of the soldering done.

-- 2012 came crawling in --

4th of January: I noticed I put in the JFET's the wrong way on one of the channels after AMB gave me some help diagnosing it. I contacted Glass Jar Audio for replacement parts the same day.

8th of January: The JFET's were dispatched.

31st of January: I replaced the JFET's, and I connected all the boards together in the case in which I drilled the holes a couple weeks before. However, it didn't work and it took quite a bit of conversation between me and AMB to come closer to fixing it. Our coversation can be found here.

26th of February: I got the two boards to be in working order. Sort off. There was an enormous amount of background noise, and the amplifier was far from usable. I decided to put the transformer in a separate case to avoid induction from AC wires and the transformers magnetic field.

28th of February: I ordered a new cage for the transformer, as well as some connectors.

29th of February: I wrote a blog post with pictures detailing my progress. The pictures aren't visible anymore for some odd reason.

3rd of March: I decided to put speaker taps on the amp. I ordered the parts required for this from Glass Jar Audio.

17th of March: Built the transformer box. Amp refused to turn on, and transformer box became hot.

-- Exams and deadlines with school came in, so the project was on hold for about two months --

30th of May: Restarted diagnosis. I found that the initial problem was caused by a short in the DIY'ed connector.

3rd of June: Ordered new transistors in the hope the issue was with those. It later turned out it wasn't.

20th of June: Ordered new JFET's for one channel, and a new MOSFET for the other channel. The latter caused some magic smoke and died, along with two scorched resistors.

-- I went on a long vacation to the US and Canada --

11th of August: The JFET's and new resistor hadn't arrived yet after I got back from a long vacation. I reordered the resistors from a local shop, and I contacted Glass Jar Audio about the JFET's not arriving.

18th of August: The JFET's were sent to me anew, free of charge.

24th of August: The JFET's and new resistors were in and I replaced the necessary parts. Still did not work. I decided to give up hope and order two new PCB's and order all the transistors, diodes and small resistors and capacitors anew. Leaving only a couple parts unrefreshed. However due to money shortage, and book purchases for school coming on I decided to wait with ordering until after the 5th of September.

28th of August: Made this thread. Here are some pictures of the current status:
(I might retake the pictures with better lighting and camera tomorrow)

-- Project went on hiatus because of money and school --

7th of October: Ordered all the parts to build two new Beta22 boards from scratch except for the heatsinks. Total cost was $230.
Passed the 1-year mark as well.

 

[Swimsonny]

WOAHH!!!!! That looks hell complicated

 

[KimLaroux]

Wait, you can actually power speakers with the beta22?!? I didn't know that.. makes it even more interesting for use on a computer desk.

 

[qusp]

depends on the speakers

 

[Tilpo]

Wait, you can actually power speakers with the beta22?!? I didn't know that.. makes it even more interesting for use on a computer desk.

depends on the speakers

Yep.

It can power small bookshelf speakers, or most small studio monitors. They don't need a whole lot of power.
It can also drive Lambda series Stax headphones via an energizer, which is what I'll mainly be using the speaker taps for, since I'll probably be upgrading my desktop speakers to some active ones.

But don't expect it to drive any big floor standers or subwoofers. For that you'd need a separate power amplifier.

 

[qusp]

nah I would disagree that it will power most small studio monitors, not enough voltage swing. if it werent for the crossover I would agree, but the crossover and porting (bass reflex is common in small monitors) can really ruin the sensitivity of multidriver speakers. now fullrange drivers it wouldnt have much/any trouble at all

 

[Tilpo]

nah I would disagree that it will power most small studio monitors, not enough voltage swing. if it werent for the crossover I would agree, but the crossover and porting (bass reflex is common in small monitors) can really ruin the sensitivity of multidriver speakers. now fullrange drivers it wouldnt have much trouble at all

Fair enough.

I'll test driving them directly from the Beta22 when I finally finish it. But if it doesn't work I still have a pretty decent power amp as well.
It has a little too much hiss when driving my Stax, but on speakers you can't hear it.

 

[qusp]

suppose it depends on how loud you listen and the cabinet/XO in question, common sense would say its not enough, but hey not everything obeys such deductions. for sure people are using less powerful chipamps to run monitors

 

[Tilpo]

suppose it depends on how loud you listen and the cabinet/XO in question, common sense would say its not enough, but hey not everything obeys such deductions. for sure people are using less powerful chipamps to run monitors

Well, I for one don't do it very loud at all.
At the loudest it still well below conversation SPL. It's hard to convey SPL in words, but my mechanical keyboard is at least 3-6dB louder than my speakers.

I only use my speakers when I want to have music on the background but don't feel like having headphones on for whatever reason. Since it's only meant to be on the background I don't feel the need for it to be loud.

 

[qusp]

yeah you can only try it and see I guess. do you know how efficient your speakers are?

 

[Tilpo]

yeah you can only try it and see I guess. do you know how efficient your speakers are?

I don't.

It just said that they are rated for 30W maximum and have an impedance of 4Ohm

But the Beta22 should come pretty close to said 30W, IIRC

 

[KimLaroux]

Quote:

nah I would disagree that it will power most small studio monitors, not enough voltage swing. if it werent for the crossover I would agree, but the crossover and porting (bass reflex is common in small monitors) can really ruin the sensitivity of multidriver speakers. now fullrange drivers it wouldnt have much/any trouble at all

 
Interesting. I didn't know crossovers had an effect on speakers sensitivity.
 
I did precise "at a computer desk", as in close-field listening. I'm using a multimedia stereo at my desk, and normal listening level never goes beyond 10% on the amp's volume. With the right speakers, it could be an option. Especially for someone who already have the Beta22 on desk, and needs small speakers.
 
But regarding voltage swing, I just thought about something. Would a balanced Beta 22 have twice the voltage swing? My understanding of balanced amplifiers tells me it would, but I'd like a confirmation before I sort this information as facts.

 

[qusp]

Quote:

 
Interesting. I didn't know crossovers had an effect on speakers sensitivity.
 
I did precise "at a computer desk", as in close-field listening. I'm using a multimedia stereo at my desk, and normal listening level never goes beyond 10% on the amp's volume. With the right speakers, it could be an option. Especially for someone who already have the Beta22 on desk, and needs small speakers.
 
But regarding voltage swing, I just thought about something. Would a balanced Beta 22 have twice the voltage swing? My understanding of balanced amplifiers tells me it would, but I'd like a confirmation before I sort this information as facts.

yep, crossover and cabinet design have an effect on sensitivity, the effect can be profound.
 
yes balanced has double the voltage swing, but it also lowers the apparent impedance, so it depends on the amp, speakers and power supply whether it nets you any more power

 

[Tilpo]

-- Update --

Ordered enough parts to build two new Beta22 boards. The only part I didn't order anew are the heatsinks.

The project has now passed 12 months of build time and $1k of components.
I feel depressed.

 

[jdkJake]

Have you given up debugging your original build?