[Emon]

Going by the cost estimates here, and ignoring that $75 for heatsinks is a complete ripoff if you know where to look, it adds up to $365. Now I keep hearing people say how expensive the Dynahi is...is that for DIY or a prebuilt aftermarket by like HeadAmp or Veda-Audio? HeadAmp's custom Dynahi is around $1,700 if I recall, which I suppose isn't too bad if you consider the hand work that goes into it, and say 100 percent profit. It seems to me that a DIY Dynahi is incredibly cheap for what I've heard is one of the best dynamic amps, period. Also why is it that Dynahis are considered such a huge challenge to build? I see nothing but transistors and resistors, a few caps and other parts. I assume most people aren't comfortable with the actual building with the heatsinks, chassis, etc, the actual good-with-your-hands work?

 

[tkam]

I don't think it's about being that hard to build, I think the concern is really the heat it puts off you need a heck of a lot of heatsinking and plenty of clearance around the amp.

 

[Emon]

Or perhaps the concern that one might not heatsink it properly and all that money will get cooked?

Hmm, if I do build one this summer, I'll be sure to lap all heatsink contacts, use plenty of thermal goop, and I might even add a quiet (like VERY quiet) fan in the back of the housing as an exhaust. With a few vents/holes in the front. I know the moment I mention fan people with open cans would freak heh, but with the right Panaflos (or other high quality quiet fan) you shouldn't hear it even at low levels of listening...me personally, I'd be using my PC as a source and...well with my PC, I could add ten fans and not tell the difference. :/

[/rant]

 

[Emon]

Oh I also had another Dynahi question that I might as well post here. What's with the stepped attenuators? What's so much better about them over a high quality potentiometer such as an Alps RK27 (Blue Velvet if my memory serves)? Just a preference or what? I see a lot of emphasis on them and I was wondering what the deal with them was. I can see the precision of a stepped attenuator with all its resistor matched goodness but honestly...can you really tell the difference? Then again that's a dumb question to ask on Head-Fi. Someone can ALWAYS tell the difference, reguardless if there is a difference or not.

 

[gsferrari]

It is quite hard to build, debug, do the chassis work and get the finished product. Not as easy as slapping all parts together and saying a prayer before you turn it on.

Just look at Raul's (rsaavedra) nightmare building the Dynahi.

$75.00 for the heatsinks is a bargain

custom made, pre-drilled, rounded edges, correct choice of material and contact surfaces...

This is no PPA, MMM, CMOY.


As for the advantages of a stepped attenuator: simply put:

* better channel matching
* less crosstalk
* better repeatability and reliability
* higher bandwidth
* looks and feels darn good

 

[rsaavedra]

Quote:

Originally Posted by gsferrari Just look at Raul's (rsaavedra) nightmare building the Dynahi.

Oh come on Guru! Don't call it a nightmare, I did enjoy the process a lot. Well ok, it was kind of nightmareish, but enjoyable

 

[skyskraper]

maybe you should check over the bom yourself and price up the parts specific to your situation.

enclosures, pots, connectors, capacitors, resistors, can all add or subtract vast sums to your total build cost.

dont forget to budget for power supply, extra transistors for matching, and tools that may be required as part of the build.

I think i priced a dynahi out at aprox 450usd total cost about the cheapest level i wanted to hit. But I think I'm going to build it up a bit, hell its about the best diy amp around atm. Why not?

 

[Emon]

What exactly is involved in debugging/tweaking? For some reason I was under the impression that the Dynahi parts list was pretty solid, and provided you bought exactly those parts, you shouldn't have too much trouble. Granted, as you said, it's not just plug and pray, but the circuits just look so simple to me that it seems difficult to mess up.

Quote:

custom made, pre-drilled, rounded edges, correct choice of material and contact surfaces...

Ah see, I didn't consider that. I would be happy with a stock aluminum heatsink, drilling and tapping, breaking any sharp edges, etc, all by myself. I'll probably get chewed out for this, but it seems a $75 heatsink is just another thing audiophiles like to blow money on to make them feel that their setup is even better than it already is. To a certain degree anyway.

 

[gsferrari]

Quote:

Originally Posted by rsaavedra Oh come on Guru! Don't call it a nightmare, I did enjoy the process a lot. Well ok, it was kind of nightmareish, but enjoyable

Yeah...im sure you enjoyed a lump of metal and silicon

But you sure as heck learned a lot didnt you?

I think everyone who has the tools, desire and a bit of technical skill SHOULD try the Dynahi. I think you will learn more in the process of building this amp, spend more than enough money to build two amps...and end up with one...

but at the end of it you will have a silly grin on your face when you get the low down with your favorite music, cans and beer...

Life is good

If you are thinking of building it - go for it!

 

[GoRedwings19]

This is the thing I admire most about DIY'ers and people who build them for a living. I suppose any tom, dick and harry could build one following instructions. But if it didn't work, would you know where to look if it didn't work on power up.

This is not painting by numbers, people. I have the utmost and greatest admiration for people who build any kind of amp. Me? I couldn't even build a CMOY let alone anything more complicated!!!!

 

[gsferrari]

Quote:

Originally Posted by Emon What exactly is involved in debugging/tweaking? For some reason I was under the impression that the Dynahi parts list was pretty solid, and provided you bought exactly those parts, you shouldn't have too much trouble. Granted, as you said, it's not just plug and pray, but the circuits just look so simple to me that it seems difficult to mess up.

Matching resistors is ok...caps is ok...transistors is NOT fun NOT easy and NOT something you can do during the commercial breaks

Quote:

Ah see, I didn't consider that. I would be happy with a stock aluminum heatsink, drilling and tapping, breaking any sharp edges, etc, all by myself. I'll probably get chewed out for this, but it seems a $75 heatsink is just another thing audiophiles like to blow money on to make them feel that their setup is even better than it already is. To a certain degree anyway.

The heatsinks are real, expensive when you do them in small quantities and unless they are properly done...they are ineffective.

If you do it - do it right - dont do it cheap. You spend waaaaay too much money on every other part of this amp to risk having a meltdown because you cheapened out with the HS.

 

[00940]

I suppose this is all relative anyway. Compared to even a Zen or a ESP P3A (popular speaker amps), the dynahi looks like a rather easy build. But people here are more used to small amps easily cased in hammond boxes and with no real power dissipation. Different crowd, different view.

 

[eastside504]

I havent built one yet, as i'm still finishing up my dynalo. However the price of ~$365 is not the true cost of building this amp. While you can buy these parts for that much, the project really require that you buy extra transistors and resistors so that you can get match pairs. There are many comments about buying enough parts to build two dynahi just to build one matched stereo amp.
Many people also dont have the tools required for the extra case work that this amp requires. Also trouble shooting is complicated.

 

[Emon]

Quote:

Originally Posted by gsferrari transistors is NOT fun NOT easy and NOT something you can do during the commercial breaks

Hmm, what exactly is involved in transistor matching?

Quote:

The heatsinks are real, expensive when you do them in small quantities and unless they are properly done...they are ineffective.

Here's the thing though. Aluminum is aluminum. Well, machined aluminum is machined aluminum. There's no mysterious element that seperates one brand of heatsink from another other than the design. I think I have enough experience frying stuff to make sure I do it right.

 

[gsferrari]

I dont want to get into an argument but not all aluminum is aluminum...that should suffice to say the least. there are different varieties...densities...alloys...manufacturing methods (extruding vs moulding vs machining), surface treatments, impregnation...

its another science if you want to get into it