New development on old project: Roger Mayer RM58

Help Support GroupDIY:

soapfoot

Well-known member
Joined
Dec 27, 2010
Messages
448
Hi,

I'm basically done populating my boards.

One question...

How critical are C10, C11, C12? I couldn't find the MKS2 Wimas listed in the BOM. The next shipment is going to be in late April! I can't wait nearly 5 months for caps to come in! First world problems! LOL.

FWIW, I used Vishay/Roederstein MKT1813 polyester axials on their sides. Specifically, MKT1813447065: https://www.mouser.com/ProductDetail/75-MKT1813447065

OK to use?

Thanks,
Chris

FVsZkDo.jpg

Definitely no problem at all.

The only thing that's really critical in these units is the matching of Q10 and Q14... those have to be very tightly matched with each other, and if building a stereo unit, all four have to be very closely matched.
 

fazeka

Well-known member
Joined
Jun 3, 2004
Messages
1,122
The only thing that's really critical in these units is the matching of Q10 and Q14... those have to be very tightly matched with each other, and if building a stereo unit, all four have to be very closely matched.

Thanks for your reply.

I haven't matched transistors before and I found the process kind of challenging due to the Idss values dropping over a few seconds and changing when reinitiating the tests. What would be something to look out for (in a completed unit, sound-wise) if Q10 and Q14 are not very closely matched?

Thanks!
 

soapfoot

Well-known member
Joined
Dec 27, 2010
Messages
448
One of them is in the meter circuit, so the matching is with the aim of getting the meter to display gain reduction accurately, as far as I know.

In my estimation, the metering isnt the most precise or useful in these units, anyway. Side-to-side balance is most important to me, but I still was pretty careful about matching all four in my unit.

Please be advised that most people on this forum have forgotten more about electronics than I’ve ever known… this was just a pandemic project for me as kind of a learning experience. All of my training and experience is in music, not electronics… so I may not be right about everything.
 

Alyss

New Member
Joined
Jan 4, 2022
Messages
8
Location
central europe
I've been hunting for 2N3820 and I got an offer for what seems to be a fair price. Those are from Central Semi - I want to know if anyone else is interested - the price is $0.165/pcs
 

grid_stopper

Well-known member
Joined
Mar 2, 2016
Messages
100
I've been hunting for 2N3820 and I got an offer for what seems to be a fair price. Those are from Central Semi - I want to know if anyone else is interested - the price is $0.165/pcs
I would likely be interested. what kind of quantity?
 
Top