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KG Balanced Dynahi build discussion thread


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#1 Vortex

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Posted 10 September 2011 - 03:27 PM

Now that the PCBs are finding their ways to us -Balanced Dynahi Builders-, I think that it's time for starting a build discussion thread for this beloved amplifier.

The purpose of this thread is to create a place for builders to discuss all topics related to the build of this amp (parts, constructions, troubleshooting...), to share experiences and to consolidate the information and discussions about this project.

Schematics of the Balanced Dynahi and the associated Power Supply by KG.
Background information about the original KG Dynahi can be found here.

Based on the preliminary BOM posted by Lil Knight earlier, an updated version for the Dynahi and the associated power supply, including Mouser parts numbers for the not yet specified parts in the preliminary BOM can be found in the attachment.
For the resistors, Vishay-Dale alternative parts numbers are added for people who like to use Vishay-Dale resistors.


Happy building. Posted Image


Attached File  BALANCED DYNAHI_BOM.xls   24.5KB   670 downloads

Edited by Vortex, 20 September 2011 - 01:14 PM.


#2 livewire

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Posted 10 September 2011 - 08:08 PM

Is there an equivalent to this amp in the commercial world?
Maybe a Headlamp Gilmore XXX or something?

FWIW, I'm kind of interested in building this now to drive my new cocobolo Grados.Posted Image

#3 deepak

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Posted 10 September 2011 - 08:19 PM

FWIW, I'm kind of interested in building this now to drive my new cocobolo Grados.Posted Image


What about a DynaToob Posted Image

AFAIK there is no commercial equivalent to the Dynamite

#4 livewire

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Posted 11 September 2011 - 03:34 AM

The Bamaslama, true KG madness! Posted Image
Did that design ever see the light of day?
The thread just petered out. I just read the start and finish. Not start to finish...

#5 Vortex

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Posted 11 September 2011 - 05:36 AM

I have updated the first post with a BOM including Mouser parts numbers for the not yet specified parts in the preliminary BOM posted by Lil Knight earlier.

#6 aRRR

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Posted 12 September 2011 - 06:09 AM

Thanks vortex, for starting this thread.

Guys, newb here but Im eager to learn so Id appreciate any help. Right now I'm acquiring the parts for the Dynahi but I'm having some issues. When you look at the BOM and this layout(http://gilmore.chem....u/dynahibal.jpg) you can see there are two capacitors (470 uF/50v) Yet on the amplifier board itself there are six places for capacitors 470 uF / 35 v. Can anyone tell me which ones I need, preferably with a part number?

And my second question, would it be a good thing to spent a bit more for higher quality parts or should you strictly follow the BOM with its part numbers?

#7 Vortex

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Posted 12 September 2011 - 07:39 AM

You are correct that the final Dynahi PCB is a bit different than the layout under that link.
The PCB indeed has place for 6 capacitors: 3 on the positive rail and 3 on the negative rail.
These are local filter capacitors, the amp will work fine with 1 or 3 capacitors on each rail.

Since the amp is feeding by ±30V DC rail voltages, the used caps need to be rated at a higher voltage than 30V.
Capacitors rated at 35V (minimum) or higher (50V, 63V) can be used, as long as they fit the board.

Some examples of 470µF capacitors are:

Panasonic FM (Digi-Key P12400-ND)
Nichicon HE (Mouser 647-UHE1J471MHD)

About spending on higher quality parts, there is no general answer for that.
For the active parts (transistors/JFets), you have to follow the specified parts (or alternative parts in some cases).
For the passive parts (resistors, capacitors, volume pot…), one can go for boutique parts, but as long as they fit the board of course. (things you have to find out yourself)

Edited by Vortex, 12 September 2011 - 11:50 AM.


#8 Vortex

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Posted 12 September 2011 - 01:20 PM

One little note about the parts list for the power supply board.

As most of you already know, the PS board consists of a ±30VDC section and a lower voltages (3.3V, 5V and 12V) section.
The ±30VDC PS is used by the Dynahi. The lower voltages are only necessary if you are going to use relay-based stepped attenuator (for example: KG stepped attenuator or AMB δ1 stepped attenuator…). Otherwise you can skip the lower voltages section.

More precisely, the following parts can be left out of the PS:

Bridge Rectifier for 18V AC section
LM7805 - 5V regulator
LM7812 - 12V regulator
Murata 3.3V DC converter
1x 4700uf/63V capacitor
3x 1000uf/25V capacitors

#9 aRRR

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Posted 13 September 2011 - 06:18 AM

Awesome. Thanks for your time Vortex, that is some useful information to me. I think it is wise to be sticking to the more basic parts for my first build.

#10 deepak

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Posted 15 September 2011 - 07:29 PM

I have a bunch of 1/4w PRP resistors for a Dynahi build (s/e) if anyone wants them I'll let them go really cheap. You'll just need to pick up a set for the second half if you're building a balanced one. gone

#11 Vortex

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Posted 01 October 2011 - 10:34 AM

Has anyone started stuffing (or touching Posted Image ) the Dyna PCBs yet?
I was busy today and this is what my boards now look like.
The small things on the back are stacked KG stepped attenuators (for balanced use) and a LCDuino-1 processor.
Still lots of (case)work to do...



Posted Image

#12 livewire

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Posted 01 October 2011 - 01:27 PM

Nice work!
Your project is evolving rapidly, cant wait to see the finished goods.

#13 ujamerstand

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Posted 01 October 2011 - 01:35 PM

Very Nice! What are your plans for the enclosure? :)
Posted Image

#14 cobra_kai

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Posted 01 October 2011 - 02:40 PM

Looks nice Vortex. Did you need to make any changes to the lcduino to work with KG's attenuators?

#15 Vortex

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Posted 01 October 2011 - 03:22 PM

Very Nice! What are your plans for the enclosure? Posted Image


To keep things simple, I will go for something relative cheap and easy to get.
Probably this one or… this one. Both are made in Europe, so shipping cost is not a big issue.
The Dyna PCB’s are designed for this kind of enclosure. Posted Image

#16 Vortex

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Posted 01 October 2011 - 03:24 PM

Looks nice Vortex. Did you need to make any changes to the lcduino to work with KG's attenuators?


I have not tried it out yet (will do soon), but I think that LCDuino will have no problem with KG attenuators.
For the processor, it’s just an 8 bits relay-based stepped attenuator (like any others from the same family).
Only point that needs attention is the 12V PS for the relays on KG attenuator boards.

#17 Kerry

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Posted 01 October 2011 - 06:42 PM

Looking good :)

#18 swt61

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Posted 01 October 2011 - 10:03 PM

Has anyone started stuffing (or touching Posted Image ) the Dyna PCBs yet?
I was busy today and this is what my boards now look like.
The small things on the back are stacked KG stepped attenuators (for balanced use) and a LCDuino-1 processor.
Still lots of (case)work to do...



Posted Image


Well work even faster, as I always look forward to seeing your final products! :)

#19 kevin gilmore

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Posted 08 October 2011 - 08:29 AM

silkscreen error on the dynahi power supply board.

The resistor labeled as 40k for dual tracking should be 20k.
schematic is correct.

#20 kevin gilmore

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Posted 08 October 2011 - 04:39 PM

notice to people doing the dynahi power supply boards.
If you are using the lm4040, make sure you buy the 10 volt versions.
Otherwise you end up with the biggest +/-15 volt around :D

lt1021 definitely a better part, and not a lot more money if you buy from digikey.




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