I was able to dial in the bais correctly by increasing the resistance to 1k.  Now the DC offset is 20v.  Not 20mv but 20V.  I am not sure if I went overboard by changing the resistance so much or I fried some parts.  

Last time the offset went that high I fried all the npn and pnp transistor

Edited July 26, 201510 yr by mahdi8

Hi guys

 

I'm finalising my case ventilation. I have put 28 holes with 1.5cm diameter each on the top and bottom of the case and the amp is still running to hot for my liking. I measure the heatsinks is around 85-90 degrees Celsius. That's after the amp running for 2 hours

What's the normal heatsink temperature for the on board heatsinkheatsink version? BTW the case has 2 s22 power and 2 amp board.

Edited August 23, 201510 yr by mahdi8

mahdi8  

I don't know the science but have found that I need 5mm holes or it doesn't vent well.

On the onboard KGSSHV top I used 323 5mm holes, and its still over 60C in some spots

and yes It was fun drilling those out larger as I started with 3.25mm

others here would have better information but I would think you need much more holes and bigger

also like a CPU 60C is comfortable.

still need to case my own Dynahi.........

Yikes 323 holes? Don't think I will have the patient to drill that many. I'm considering 3d cutting mdf so i cam easily make lots of holes and painting it for the top part and bottom. Not not sure about the integrity of the mdf after cutting too much holes in it

I just run it with the bottom case open for now. Most of the heatsink is running under 70 degress only one heatsink is showing 80 degrees. I might adjust the bias again but for now should be all good running it this way. until I have time to redo the case

What do you think of its sound ?

Edited August 25, 201510 yr by G600

Sounds Brilliant. For me it's as detailed as it's get from any amp. and scales well with better DAC. compared with my old amp moving to a better DAC gives a more noticeable difference using Dynahi

Coming from 70 holes at the top and bottom only which running at a high 82 degrees C. I've drilled much more. Top and bottom now has total of  118 holes and the sides has total of 48 holes. Now the hottest transistor running at 65 degrees C. Pretty happy with that. It was lot of drilling. I almost warped the top and bottom plates from the drilling.

 

Now it's just a matter of resurfacing and repainting the case now. Cos lots of holes on stainles steel look like a cheese grater lols

Coming from 70 holes at the top and bottom only which running at a high 82 degrees C. I've drilled much more. Top and bottom now has total of  118 holes and the sides has total of 48 holes. Now the hottest transistor running at 65 degrees C. Pretty happy with that. It was lot of drilling. I almost warped the top and bottom plates from the drilling.

 

Now it's just a matter of resurfacing and repainting the case now. Cos lots of holes on stainles steel look like a cheese grater lols

congrats,would like to  see the finished build !

And here is the finished build. By far the most transparent I amp I have ever tried. Kudos to KG its a brilliant design

Hi. New here, but soon getting my Pioneer SE Master 1 so I am very interested in headfi. Any chance to buy PCBs for balanced Dynahi's somewhere? (aka Dynamite/Dynamight if I understand it right). I am a skilled builder and want to try this project.

There is no group order at the moment. Only option is to go to a pcb maker with the design and get your own

 

I have been using a dynamite for about a decade. It is the first version with the 4 identical channels from the djgardner boards. It was built for the Akg k1000 and now I am using for the He6. The volume controller was a 24 steps stepped attenuator similar as Dact but cheaper. For a time it caused noise problems maybe the switch too that switched the single ended  and balanced inputs. Now I removed them because most source has volume control, the quality much improved I am thinking about I only need 4 steps to reduce the volume with for example 10,20, 30 dB depending on the headphone k1000,he6,he500 etc. So the question is some 4 pole 4 pos shorting (not crucial to be shorting,or mbp ) switch sealed as good relays is this exists ? Because they say an only software volume control maybe dangerous as for example the direct coupled amps   . (The same question about the 4pdt or 4 pole 2 pos input switch)

 

Edited September 29, 201510 yr by judo
correction

I'm thinking of using a Twisted Pear Joshua Tree attenuator to control the volume.  Do you guys think it will work ok?  I have the off board heatsink version of the Dynahi.  Here's the description:

http://www.twistedpearaudio.com/control/jt.aspx

Joshua Tree is a logarithmic stepped attenuator with 128 steps + mute. It utilizes eight Omron G6K relays and can be setup for any degree of attenuation per step and any total amount of attenuation. The kit uses Vishay/Dale 1% CMF resistors, providing 0dB to -63.5dB of attenutation (+ mute) in .5dB steps. The kit's input impedance varies between 2.2K and 10K, with a fixed output impedance of 750R

Do you guys think this will be ok to use?

I want to order some dynahi boards with the surface mount parts and was wondering if anyone has built one to make sure that everything works.  If anyone wants some boards as well I think I might have a couple of extra depending on how many I order and how much interest there is.  I will only be ordering the on board heat sink ones.  

I could use a pair.

I'm thinking of using a Twisted Pear Joshua Tree attenuator to control the volume.  Do you guys think it will work ok?  I have the off board heatsink version of the Dynahi.  Here's the description:

http://www.twistedpearaudio.com/control/jt.aspx

Joshua Tree is a logarithmic stepped attenuator with 128 steps + mute. It utilizes eight Omron G6K relays and can be setup for any degree of attenuation per step and any total amount of attenuation. The kit uses Vishay/Dale 1% CMF resistors, providing 0dB to -63.5dB of attenutation (+ mute) in .5dB steps. The kit's input impedance varies between 2.2K and 10K, with a fixed output impedance of 750R

Do you guys think this will be ok to use?

I would think that it would work fine, though maybe Kevin's attenuator or even Amb's might be a better choice? There is a group buy for Kevin's attenuator about to commence.

I'm tempted to build this to get an amp that can drive my old orthos once and for all.

Does anybody have boards, and is there a one box compact version?

 

Has anyone tried a Lightspeed Attenuator?

What do you think of this design? Maybe it's a stupid idea but I think that it's an interest alternative.

Look up Nelson Pass's distortion measurements of the said attenuation method. They weren't too pretty.

I use a combination of 24 step stepped attenuation for coarse steps and 28bit digital volume control for finer adjustments. Complex, but gets very good results.

Ok Rudewolf. I need take a look. Is it so bad?

On DIYAudio was working on differents versions of the same concept.

I've never seen an LDR that measures at an acceptable level. 

7 minutes ago, spritzer said:

I've never seen an LDR that measures at an acceptable level. 

Ok, thanks

Do MPSA06/56 work for the output stage or do they burn?

Any MPSW06/56 stashed away?