[kevin gilmore]

The board with the heatsink

http://gilmore.chem.northwestern.edu/dynahi2.jpg

200khz square wave into 33 ohms
(i keep burning up the 5 watt load resistors)

http://gilmore.chem.northwestern.edu/dynahi3.jpg

Yet to install and test the servo...

Finished pic
http://gilmore.chem.northwestern.edu/dynahi4.jpg

 

[Sewer Guy]

Most impressive! Very clean. Are you accepting contributions for new load resistors?

 

[Iron_Dreamer]

Yee-haw, wow! Keep it coming KG! What will the master produce next?

 

[JohnFerrier]

Hi Kevin,

That is really nice. Thanks for sharing. I wonder though, why some many amplifiers? I'll confess your pictures do make me interested in building a DynaHi...hmmm....geez it's such an investment in time....kind of like just listening now... dunno... maybe....


JF

 

[kevin gilmore]

quote
I wonder though, why some many amplifiers

I keep designing better and better things. Which generally means
more money in parts and increased physical size and power consumption.
Also better parts become available. Which is definitely the case for
the output transistors used in this amplifier.

I'm doing the dynahi and the mig/mig2 this year.

Then that is going to be it for quite a while for headphone amplifiers.
For electrostatic amps, i don't know how to do anything better than
the blue hawaii. For dynamic amps the dynahi and the mig/mig2 are
about as far as i can go there too.

Next year, production uberamps. 400 and 800 watt units.

There is a new preamp in there somewhere.

There is something else somewhere in there too

 

[JohnFerrier]

Quote:

Originally Posted by kevin gilmore Next year, production uberamps. 400 and 800 watt units.

Yep, seems there is a niche that you can fill...

I need to check into the mig/mig2...

And at your convenience...any way to work in that novel Bryston output design?


JF

 

[Edwood]

Woah. I'm going to have to try building that one some day. Perhaps I should at least be able to build a Gilmore Lite, first.

I suppose my circuit schematic illiteracy won't help either. (ok, not totally illiterate, just not very advanced)

-Ed

 

[was ist los?]

Kevin, nice work!!! What do you think is more suitable for Grados, the Dynahi or Dynamic? Will there be a balanced bridge version of this amp?

 

[some1x]

Will this be a doable project for someone who has never attempted to build an amp before? :

 

[gsferrari]

1] I see a empty slots in parallel with the resistors. What are those slots for?

2] Where can I find schematics of this amp?

Now - the volume question :-
----------------------------

Mr. Gilmore,

Would it be more productive if we used a switching circuit which enabled/disabled amplifier blocks depending on the required volume? Wouldnt this offer better sound quality and lower power consumption (also less heat production in Class-A amps) than a Potentiometer/Stepped Attenuator controlled system?

Basically turning on/off amplifier blocks to control volume instead of using passive components...

Is this even possible? What do you think?

 

[commando]

Quote:

Originally Posted by kevin gilmore Next year, production uberamps. 400 and 800 watt units.

Yeah but how will my CD3Ks sound with them?

 

[Demolition]

Thanks for the photos of the Dynahi board, Kevin. Much more interesting than your mangled finger.

D.

 

[kevin gilmore]

quote
1] I see a empty slots in parallel with the resistors. What are those slots for?

various other options. For example 2 x 20 ohm resistors in parallel for the
emitter load resistors instead of 1 x 10. Lower inductance. Makes a significant
difference because the amp has a slew rate of several hundred volts/usec.

2] Where can I find schematics of this amp?

http://gilmore.chem.northwestern.edu/dynahi.gif

However there are numerous changes
The 2 x 15k on the left are 30k
The 510 in the middle is 100
the 2 x 510 at the top and bottom are 150
The 2.5 ohm resistors are 10 ohm or 2 x 20 in parallel each
The 20k feedback is now 2k
The 1k to ground is now 100

quote
Would it be more productive if we used a switching circuit which enabled/disabled amplifier blocks depending on the required volume? Wouldnt this offer better sound quality and lower power consumption (also less heat production in Class-A amps) than a Potentiometer/Stepped Attenuator controlled system?

If you are talking of some kind of class H circuit all i can say is YUUUK.
Better sound quality, not a chance. None of the multistep designs can
switch fast enough and putting a delay line in series with the audio signal
so that this could be acomplished would do more harm than good.

Lower power consumption, who cares. This is not a portable amplifier.
This amp only pulls a total of about 30 watts.

The mig2 amp uses 288 watts just to light up the filaments!

quote
Will this be a doable project for someone who has never attempted to build an amp before

Depends on how good you are at the mechanical aspects. Drilling and
taping the heatsinks, mounting everything... Stuffing the board is easy.

Many more pictures as soon as the rest of the parts get here.
Still missing some resistors and one of the heatsinks.

 

[aerius]

Time to make a trip to the local electronics supply shops to see if they have everything. If they do I've just found my next project.

 

[rsaavedra]

Quote:

Originally Posted by kevin gilmore This amp only pulls a total of about 30 watts.

So I assume this is not a headphone amp, is it easy to make one (a headphone amp that is) with this same circuit design? That ripple-free square wave on the occiloscope is amazingly clean.