I have removed all the sockets and this cleared up the oscillation problem, and it also sounds much better.

The zobel network cleared up the problem with high mv reading when phones are plugged in and volume is turned off. What would cause that to happen?

Frank

[Edited by fc911c on 12-25-2008 at 07:28 PM.]

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[Quoting fc911c]

I have removed all the sockets and this cleared up the oscillation problem, and it also sounds much better.

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[Quote]

The zobel network cleared up the problem with high mv reading when phones are plugged in and volume is turned off. What would cause that to happen?

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[Quoting amb]

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[Quoting fc911c]

I have removed all the sockets and this cleared up the oscillation problem, and it also sounds much better.

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Excellent!

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[Quote]

The zobel network cleared up the problem with high mv reading when phones are plugged in and volume is turned off. What would cause that to happen?

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There was some inductive load related instability, probably caused by the output wiring (or maybe your headphone cables, are they stock Sennheiser or afterarket?). The zobel compensates for such a problem.

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Yes they are the stock Senn cables and yes the output wiring is a little long right now.

thanks
Frank

And another question: for the PN4392 at the AMB audio shop you wrote that the pair was 'tested'. So that means it's different from what I would get if I bought from mouser?

[Edited by scytheavatar on 12-26-2008 at 05:38 AM.]

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[Quoting scytheavatar]

Question: is there any differences between the Panasonic FC and the Nichicon HE capacitors? I was trying to get everything from Mouser and I was wondering if its worth it to order the FCs from digikey...

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[Quote]

for the PN4392 at the AMB audio shop you wrote that the pair was 'tested'. So that means it's different from what I would get if I bought from mouser?

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Can someone recomend a good speaker that mates well with the B22 in the $300-$1000 price range, floor, book shelf or DIY?

Thanks

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[Quoting fc911c]

Will two S22 PS with 100VA trans be enough to drive speakers on a 4 board ballanced B22? I have 2.5" heat tall sinks on all.

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[Quoting amb]

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[Quoting fc911c]

Will two S22 PS with 100VA trans be enough to drive speakers on a 4 board ballanced B22? I have 2.5" heat tall sinks on all.

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Only if you have very efficient speakers, in a relatively small room, and you play at moderate volumes.

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What would be needed then, an S22 for each board?

What else, are heat sinks big enough?

What do you mean by efficient speakers?

thanks

Single enclosure, SumR encapsulated transformer+s22+e22/B22, housed in a par-metal 16"x16"x4" alodine aluminum case, painted in Rustoleum "hammered black" =).

The only things I am still missing are a knob for the volume pot (RK27 at the moment) and some nice, big, rubbery feet =)

Initial impressions with Sennheiser HD600's (even though I've been listening to it for about 2 months now waiting to get it cased up): I'm amazed at the overall detail, to the point where it's incredibly obvious that I need to get a new source, even though the Alien DAC that I've been using up to this point has held its own. I'm even more amazed at the low-end detail that's been missing from everything else... from Joni Mitchell's "Carey" to Ayreons "The Shooting Company of Captain Frans B. Cocq"... The other thing I really notice is the attack of instruments such as piano, cymbal, guitar, even bass drum, which I would attribute to the slew rate of the B22 without knowing anything better to say about it

I am noticing some mid-freq hum at higher volumes, however, this is only with the Alien DAC attached as a source, so this may be due to my computer or the DAC itself. With no source attached, it's absolutely silent aside from some hiss at very high (read: unlistenable) volumes, which I am convinced is due to my choice of cost-conscious volume control.

The main thing I'm still planning on doing is adding an e12 unit in front of the e22 board (once I get one working), but until then this baby's working fine.

Many kudos to Ti Kan and the community! I may be the last guy to make one but as far as I'm concerned it's the best sounding one constructed yet

[Edited by Iniamyen on 12-27-2008 at 03:45 AM.]

[Edited by dk123 on 12-27-2008 at 04:21 AM.]

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[Quoting fc911c]

What would be needed then, an S22 for each board?

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Having two PSUs, each handling only one stereo channel, the heat dissipated by the PSU's MOSFETs will be reduced.

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[Quote]

What else, are heat sinks big enough?

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[Quote]

What do you mean by efficient speakers?

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Efficient speakers get loud without requiring as much amplifier power. Using these speakers, in a small room where not as much power is required to fill the room with sound, makes the amplifier work less hard, therefore the MOSFETs will run cooler.

Take a couple of extreme examples. The LS3/5a (a small BBC-designed studio monitor made by Rogers, Spendor and others) have an efficiency of around 83dB/W/m. On the other hand, the Klipschorn (a large floor-standing horn speaker) has an efficiency of 105dB/W/m. That's a whopping 22dB difference.

To get 105dB from a LS3/5a (which it can't really do, but let's just ignore that fact and pretend it could), it would take almost 160W of amplifier power, whereas the Klipschorn gets there with only 1W! (Note that I mention these speakers for illustrative purposes, there are large followings of both of these classics, but neither of them are to my liking...)

Since the β22 is primarily designed as a headphone amp and "light duty" speaker power amp, the TO-220 MOSFETs are not up to the task of sustained high outputs. Even very large heatsinks only help to a certain degree before the thermal resistance of the TO-220 casing itself becomes a bottleneck.

The β24 (with much larger TO-247AA MOSFETs) changes all that, of course.

[Edited by amb on 12-27-2008 at 03:53 AM.]

Frank

The hum i had with the old transformer and high sensitive phones is gone

The transformer is from Schuro: www.schuro.de/preisl-v-rkt-ms-sw.htm. I used the "V-RKT-MS-SW 50.24" (2x24V/65VA). The quiescent current is set to ~110mA. 65VA seems to be really sufficient. The transformer don't even get warm.

Will 2 of these transformers enough for a balanced B22? Looks fine with 3 ground screens.

http://www.plit...exd.asp?id=635#

[Edited by housing on 12-29-2008 at 01:09 AM.]

[Edited by dk123 on 12-29-2008 at 09:10 AM.]

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[Quoting dk123]

hi all, i just want to simplify my question earlier, would a 12.05v max diode be alright to be used for diode 1,2, 5-10

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[Quoting amb]

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[Quoting kschong]

Every time after about 5 mins of usage, when I turn the pot to a specific 9 o'clock position, there's a sharp continous humming sound through the headphones. Below that position, the humming goes away and the volume diminishes quickly. At the minimum position, the humming sound comes on again.

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Is this a two-chassis or single-chassis build? What volume pot are you using? How is it wired up? How did you do the grounding? What headphones? Maybe a clear photo would help. Also, do you have a zobel network connected to the outputs? Sometimes a high frequency oscillation can have sub-harmonics that would sound like hum.

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[Quote]

I also realise that there's a low humming sound coming from the board, literally.

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On which board? Can you identify which exact part(s) that's making the noise?

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Finally back home to check on my amp.

It's a 2 chassis build. The transformer and s22 in one box, the three boards in the other.

I'm using the ALPS rk27 blue velvet pot. I just double checked the wiring as suggested on your website and it's the same. Sorry but don't have a camera with me, so I can't show a pic .

I'm using a pair of dt880 250ohm headphones. Also, there isn't a zobel network installed at the output.

About the vibrating hum, it's from the s22. I can't pinpoint which component that's making the noise.

As for the vibrations, are you sure it isn't the transformer?

[Edited by amb on 12-31-2008 at 05:56 AM.]

- order case as plain and have Front Panel Express (FPE) make one for you front panel from scratch
- order case with fancy 10mm blank panel, ship panel to FPE and have them work on it (I believe FPE lets you provide base material)
- have HiFi 2000 do all the drilling/milling/labeling for you by providing them with CAD drawings

I am asking because each of these methods has its advantages and drawbacks. FPE made panels on their own stock suffer from lack on finish on any side that's not the front (i.e. unpolished and even rough sides, stripped anodizing etc.).

[Edited by aos on 12-31-2008 at 04:45 PM.]