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Posted

It sounds sweet and powerful, smacking bass and nice smooth highs, works extremely well with the orthos. Haven't tried the K1000 as they're out on loan for a while. Best amp I've heard to date. I haven't heard many upper end amps so I have limited experience, however, I'm extremely happy with it.

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Posted
Gary,

The case looks great but you need some ventilation. The beta is not going to last very long if you keep all that heat trapped inside.

x2 what Nate said. If you cannot go wild on the ventilation (including a vented bottom, IMHO), consider running the power supply rails lower and/or a lower bias point, as that will help with the heat.

Posted (edited)

No problem. That tile will look good with ventilation holes in an interesting pattern. Of course, Gary could always look into the Z bracket that Vlad just mentioned.

Edited by guzziguy
Posted

The vent holes are all open, the marble is sitting 1/2" above the vents and the sides are fully perforated end-to-end top and bottom. It's going to have a set of large vent holes in the top and bottom to ensure plenty of air. I've been monitoring the heat and it seems fairly happy though I am going to make certain there is enough ventilation. The original case has no vents in the base which I'm going to fix.

Posted

Nice looking case Gary!

I'd cut out all the metal under the tile. That couldn't hurt to make sure you get enough ventilation.

Once mine is recased the full top will be perforated aluminum.

Posted

How do I wire this for speakers (stax box) and headphones. I tried what I thought was workable but apparently not. I couldn't find anything on ambs site regarding wiring both so I don't know how it;s supposed to be done.

Posted

not sure if you would need a different zobel for the stax box but this is what Ti says"

audio2.png

Zobel network

In each of the three configurations above, if the amplifier is intended to drive speakers, the Zobel networks as shown (22Ω 2W metal oxide power resistor and 0.047

Posted

In some of the discussions that amb and I have had regarding the failures that have been observed at times it has been suggested that it might not be a bad idea to have a Zobel on the output regardless of the intended use.

Posted

Yeah, I did it from the jack and amb said a bunch of things that didn't compute with me and made no sense to my feeble brain..

MY POST

Ok, I have a strange problem that I don't understand, maybe someone could shed some light on it.

I wired up the speaker outs with zobel last night but something is very wrong somewhere. The speaker outs are wired from the headphone exits so they;re off when phones are plugged in. Wires go from there to the zobel and posts. Now, testing continuity and resistance, it all looks perfect. No continuity with phones in, continuity with phones out. I check the posts to chassis, open, I play something and I get a reading from positive to chassis.

I have no idea why this is, and what;s coming out of them is very quiet, distant and has a weird out of phase, sorta mono sound.

It looks right, it just doesn't work for some reason. confused.gif

AMBs POST

I don't recommend wiring the speaker outs that way. Most "switched" headphoen jacks do so on the "ground" leg, and all you're getting when iyou plug in the headphones is to lift that ground. But the speaker "grouhds" are still connected to each other, so you have, in effect, both speakers now in series across the L and R output terminals. What you're hearing is the difference signal between the left and right channels.

To make this work you'd need a headphone jack with two switches so you could "disconnect" the left and right speaker grounds independently, but even if you could find such a jack, would its switch contacts be rated high enough for speaker use?

ME

now this doesn;t make any sense to me but then I'm not the sharpest tool in the shed. I need help. What he says makes sense in what I'm hearing but from there I'm just confused. All the grounds are common anyway and the signals are just an extension of what's connected to the jack.. The Neutrik socket lifts all three contacts when the phones are in.

Posted

this is interesting nate, I toyed with adding a zobel to an unstable PPA a few years ago - was serving preamp duty and I thought it might have been a loading issue.

Any suggestions for "universal values" or just stick to the speaker zobel? ..dB

Posted

You have a part number for that headphone plug smeggy?

You may just need to buy a decent switch and manually go between speakers and headphones - little effort involved on your part and you don't have to worry about plug tolerances.

..dB

Posted

also, one of the reasons for taking it off the jack was so it'd be a easy way of switching one to the other just by plugging or unplugging the phones. Seems like that might be off the menu now.

Posted

The jack looks like it should work as you wanted. It is good for 3A.

neutrikNMJ6HC.jpg

It looks like all 3 are switching smeggy, check your ground wiring carefully to make sure it is going where you want it to be.

..dB

Posted

Smeggy,

I use the same jack on my Dynalo, which is set up to also be a preamp, with the pre-outs wired off the switched jack. I have a modified e12 on it, with a muting switch, but of course this disables all outputs. When I tried it as a pre and listened to phones, I was also getting very quiet sound from the speakers (power amp stays on all the time). I haven't figured out why it is bleeding thru but it is. All three contacts do switch, so ???

Posted (edited)

yeah, it all looks and measure fine, it just doesn't work, I'll double check tonight. I wonder if the zobel is doing something funky.

An other dumb question from the dumb question machine, running a 12V DC fan off a 6V AC supply? ;)

Hmm, I looked at my zobel and I have cap>resistor + to - and ambs diagram shows resistor>cap + to - will this do what I'm hearing, having it reversed from his drawing?

Edited by Smeggy
Posted

Probably a wiring error.

I don't have a pic, but if you look at the diagram from amb posted above, my cap is fitted before the resistor on the positive post, amb has it resistor then cap. I'm wondering if this may be the trouble, I don't really know but I imagine if it's in series the cap won't be too happy about getting the signal before being tamed by the resistor.

I bought two sets just in case :P

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