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Modifying a Coincident Dynamo Mk1

Hello all,

Have been modifying my Coincident Dynamo Mk1 for some time and I could use a helping hand from more experienced users.

If I understood correctly, looking at the image attached the 2 Epcos 22uf/500v are the filter caps which come after the rectifier (in my case the 5AR4) and these have to take into the account the rating of the tube and capacitance limit which is 60uf?

If my ramblings prove to be true can this position be improved on with better caps and/or a slightly larger caps?

Looking at the, what I think to be the power supply cap, which is a 470uf/500v, would there be a benefit in putting a larger cap without causing other issues? For instance the Mk2 Dynamo has much bigger caps in that position but I suppose the transformers are different as well. Id be looking to get more bass and mid bass and some readings say this is the place which can yield some results.

I have done several modifications already with mixed results so if anyone is interested I can share the details but Im trying to learn more about the positions and parts and their relative role. Any ideas and suggestions are welcome.

Link to insides below.

Thanks in advance!

https://ibb.co/JqW6JDb

P.S. For some reason the picture did not want to upload via the insert photo, sorry for the link.

neverlast
imhififan's avatar
imhififan
2,181 posts
 

The easiest way to bypass the volume pot is to move the two yellow wires from the center lug to the lugs for the blue and brown wires respectively.

It will eliminate any noise caused by dirt buildup on the wiper.

 

paul_lindemann's avatar
paul_lindemann
51 posts
 

Just my opinion, but Israel Blume tried dozens of Caps and values prior to deciding on the best match.

I have modified a few power amplifiers, with assistance from Robert Hovland.  Bob had an excellent comment that has stayed with me to this day.  He said that it is almost never the best Capacitor, Resistor, wiring Etc. that produces the best sound, rather it is the synergy between the circuit and components that usually will sound best. 

Of course, asking Israel, may be a good way to go.

neverlast OP
15 posts
 

Paul, thanks for joining the topic, and yes I completely agree. After trying several different caps at various price ranges my conclusion was that it is a matter of taste and one has to judge by himself. It also helps to try and forget the "bigger is better" and "cheaper must be inferior" logic and just listen. That being said, the products  have to meet a certain price point and at the end of the day it has to be a compromise to an extent so this synergy needs to make financial sense. This is where our modding comes in where we try to improve our gear and tune it to our taste.

Israel commented that he does not recommend any other mods other than the ones that were already done, and as I said I understand his point.

 

noromance's avatar
noromance
9,769 posts
 

@neverlast Why didn't you post a photo of the current amp instead of the unmodded version?

What I did do was use a pair of Mundor Supreme caps [etc.]

neverlast OP
15 posts
 

@noromance, I wanted to post the original photo of the amp for starters to see where people would suggest their own ideas for modding and maybe being a little easier to navigate, also my version does not show the values on the stock power supply cap. But if it may be of any interest to others here is the current state of the amp.

https://ibb.co/dBt4DhT

For some reason Im still having issues with the image showing in the post thus the link.

 

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