192 replies to this topic

[Vortex]

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.


 BALANCED DYNAHI_BOM.xls   24.5K   207 downloads

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

[livewire]

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.

[deepak]

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

What about a DynaToob

AFAIK there is no commercial equivalent to the Dynamite

[livewire]

The Bamaslama, true KG madness!
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...

[Vortex]

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.

[aRRR]

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?

[Vortex]

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.

[Vortex]

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

[aRRR]

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.

[deepak]

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

[Vortex]

Has anyone started stuffing (or touching ) 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...

[livewire]

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

[ujamerstand]

Very Nice! What are your plans for the enclosure?

[cobra_kai]

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

[Vortex]

Very Nice! What are your plans for the enclosure?

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.

[Vortex]

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.

[Kerry]

Looking good

[swt61]

Has anyone started stuffing (or touching ) 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...

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

[kevin gilmore]

silkscreen error on the dynahi power supply board.

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

[kevin gilmore]

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

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