[Daveze]

Quote:

Originally Posted by nsx_23 /img/forum/go_quote.gif Not to go off topic here, but I didn't want to start a new thread over something this small. Is that jaycar kit easy even for a noob to build, and how does it sound? I'm interested in some kind of home amp for my AKG K601, but am very limited in money at the moment ($100AUD-ish).

As a build, its quite easy. It gets a little tricky with the power supply because you've got line voltage on one side of the transformer but if you're careful enough it shouldn't be an issue.

The sound is quite good, I wouldn't quite rave about it (although there are those that do) but then again, I don't think I'm quite done with the tweaks yet. For the price, its definitely worthwhile. For the experience, its even better.

 

[minivan]

if u want to have more fun, buy 2 and turn them into a balanced headamp

 

[johnwmclean]

Quote:

Originally Posted by amb /img/forum/go_quote.gif The Joshua Tree is an excellent attenuator, but it has low input impedance (IIRC much lower than 10K, depending on attenuator setting). As long as you understand the implication of this and use a source or preamp that has 1/10 (or preferably lower) output impedance than that, then there is no problem using it. This is not just for β22, but is a general consideration for any amp.

My Cambridge audio 840c is > 50 ohms output impedance, so therefore this is to high for this attenuator? Thanks once again, AMB!

 

[johnwmclean]

Quote:

Originally Posted by elliot42 /img/forum/go_quote.gif Just had a read of the thread, and while I won't be buying a kit (I've got a BantamDAC, CKK3 and parts for some cables on the way that will need attending to), I could lend a hand at a DIY get together. I don't have the experience (or time) to fully build and number of B22s, nor am I great at debugging electronics. But I am alright with a soldering iron and think it would be fun to get together and do some DIY. So give me a buzz if and when you decide to meet up and do some soldering, I could help out or even just watching a B22 being built could be fun.

Thanks Elliott! Your most welcome

 

[Dres]

If the aussie dollar was just a touch stronger, I'd be all over it.

 

[nickyboyo]

Quote:

Originally Posted by fordgtlover /img/forum/go_quote.gif Hey NSX_23, you should check out this thread. That Jaycar amp (with a few tweaks) has a very keen following.

Rob, have you made one of these amps??? I think i saw one of these kits in Penrith Jaycar, and turned my nose up at it- curse you ignorance.
It looks like good fun to build and tweak. Looks like Santa is getting some new entries on my Christmas wish list.

 

[nsx_23]

Quote:

Originally Posted by Daveze /img/forum/go_quote.gif As a build, its quite easy. It gets a little tricky with the power supply because you've got line voltage on one side of the transformer but if you're careful enough it shouldn't be an issue. The sound is quite good, I wouldn't quite rave about it (although there are those that do) but then again, I don't think I'm quite done with the tweaks yet. For the price, its definitely worthwhile. For the experience, its even better.

I guess I'm more worried about working with the power supply side of things. I really don't fancy my house burning down because I shorted something.........

 

[Daveze]

Hence the mention of being careful. BTW, your concern shouldn't be the house, it should be with keeping the magic smoke in your body.

If working with line voltage is a real concern, you could have it run off +/- 12V and use the matching power supplies (there's an enclosed transformer that has 12-0-12 on a 3 pin socket, which matches with one of their +/- 12V supplies).

 

[fordgtlover]

Quote:

Originally Posted by nickyboyo /img/forum/go_quote.gif Rob, have you made one of these amps??? I think i saw one of these kits in Penrith Jaycar, and turned my nose up at it- curse you ignorance. It looks like good fun to build and tweak. Looks like Santa is getting some new entries on my Christmas wish list.

Hi nickyboyo

No I haven't built one, I did the same ignorant thing as you. The guys over at Rockgrotto seem to think it's very tweakable and offers terrific value for money.

I already have too many amps. If I were to look for a cheap amp, I'd go for it in a heartbeat.

Cheers

 

[Corky]

Quote:

Originally Posted by nickyboyo /img/forum/go_quote.gif Rob, have you made one of these amps??? I think i saw one of these kits in Penrith Jaycar, and turned my nose up at it- curse you ignorance. It looks like good fun to build and tweak. Looks like Santa is getting some new entries on my Christmas wish list.

I built one years ago, and have modded it here and there in that time. Funny how i've done most of the mods listed in that rockgrotto thread.

Must try that JLH add on...and try building a second for balanced too...maybe.

Sound wise i rate it, but i'll admit i can only compare it to a DoZ or unamped. Cans are DT250 and K701.

Regardless it's good fun to dick around with

 

[poo]

Thought I'd bump the thread... seems to have slowed somewhat.

I have purchased a serious amount of soldering gear so am now totally committed to this project. Will have a few various items on the way in the coming week to put together by way of an introduction...

Tangentsoft this whole site is excellent, but I especially found the tutorial videos helpful.

 

[johnwmclean]

Quote:

Originally Posted by poo /img/forum/go_quote.gif Thought I'd bump the thread... seems to have slowed somewhat. I have purchased a serious amount of soldering gear so am now totally committed to this project. Will have a few various items on the way in the coming week to put together by way of an introduction... Tangentsoft this whole site is excellent, but I especially found the tutorial videos helpful.

Coincidence indeed

I just received my soldering iron in the mail today! As well as my mini 3 kit from Jeff, the board is tiny, I mean really tiny

I also have heaps of other soldering goodies on there way as well! poo have you seen the tangent videos Tangent Tutorials well worth a look at!

Whoops I see you’ve been there already!

 

[poo]

A few more questions... AMB your comments would be greatly appreciated should you happen to read this.

Just to re-cap quickly, I plan to build an amp to drive my headphones (balanced and single end) as well as a 2ch speaker setup; currently Krix Neuphonix. Specifications can be found here: Neuphonix I may change these speakers in the future (of course

) so I would like to allow for that too. On to the questions...

1 I asked earlier about the possibility of building a β24 power amplifier at a later stage to use in conjunction with the β22 I plan to build now. My understanding of such a system is that I would be using the β22 as a preamp and the β24 as a poweramp; I presume that is the intention behind the design? Surely this would be the best approach in regards to driving the speaker side of my setup? Earlier comments suggested this might be 'overkill' and that I would be better off to simply build a β22 that can handle speaker driving duties (adding additional power boards and significantly larger heatsinks). I would really love some more detailed comments on this.

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif Make sure you use big heatsinks on your Beta22's, as well as your S22's (use one S22 for each B22). The stock PCB heatsinks won't do (tried it, blew up a couple MOSFETs).

2 I presume something along these lines would be required? Conrad

Quote:

Originally Posted by cotdt /img/forum/go_quote.gif higher quiescent current has its benefits as you get closer to Class A.

How do I do that now???

3 Are there any other requirements for the speaker amp side of my amp build that I have missed?

4 In terms of the boards I need to order, is the following correct? β22 x 6, σ22 x 6, ε22 x 2

Which would build:

All comments/suggestions welcome!

 

[poo]

Actually, in terms of adding larger heatsinks like the conrads I linked to above, I don't think I will be able to use ε22 boards at all; the distance from the heatsink to some of the the MOSFETs would be too big right? I presume I would have to arrange each set of 3 β22 boards vertically within a case rather than stacked horizontally like is the case on a ε22 board, just to cut down on the distance from the MOSFETs to heatsink?

 

[amb]

β22 could be used as a light duty speaker amp, larger offboard heatsinks and multiple σ22 supplies are highly recommended to handle the load.

β24 is a heavy duty speaker amp with a lot more output power. You could use a β22 as the preamp for a really over-the-top combination. The β22 preamp could be either 4-ch balanced or 2-ch unbalanced, but since β24 is intrinsically fully-differential, a balanced preamp would be ideal.

Off-board heatsinks on the β22 will preclude the use of the ε22 backplane board.