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Dared MC-7P Upgrades

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I just got the Dared MC-7P preamp; I am pleased with the sound... but not impressed. I see lots of room for upgrading here so I thought I would start a post to see what others have done with this nice little preamp.
First it responds really well to tube rolling- it is very responsive to NOS tubes.
Feel free to post your results with different tubes.

Second I popped the top and there are these huge yellow block shaped caps in it (1.0 value). I think they have to go! Has anyone had experience cap rolling with this preamp?

I am purchasing some Russian FT3's to try in my power amp, so I think I will get an extra set to try in the only place that I see room for this large cap in this cramped preamp.

I am looking forward to some interchange here so we can all make out preamps better!

Here are a few photos of the belly of the beast.
 

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My friend Phil found some ground loop issues in the Dared so he tracked them down. Here is his advice on how to fix it:
Here is a picture of the cut traces on the underside of the PC board. It is not easy to lift the edge of the PC board but just take your time and it will go. You'll have to remove the selector switch (nut on front panel behind the knob) and the volume controls (same) to lift it. Once you do, take an xacto knife and cut two slits across the copper trace as shown in the picture. Once the second trace is cut, lift out the piece in the middle with the xacto knife so there is a small gap between each.
 

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I just ordered six Auricaps from Partsconnexion to install. I will bypass them with the Russian Teflon's (.001 value) that I got on Ebay for a song. I used them before in my Jolida JD-9 to bypass Obbligato Gold's with good results.
I will post photos when done.
I will allow them to burn in for a week before I report on the sound.
Chris at Partsconnexion is such a great guy. He takes time to ask questions to make sure that you are getting the part that will make you happy. He also recommended better caps, but I wanted to do this on a budget and see what the average guy can do with it and still have some date money :)
 
Hey Wirenut, I also own a MC-7P. Can you please elaborate on what ground loop issues that Phil found? Is this something he was able to see on an oscilloscope? I'm not afraid to do the mod, just want to make sure before diving in. Looking forward to here how your Auricap and bypass cap replacement turned out.
 
I did the ground loop mod myself yesterday & it worked. I don't know about the scoping of it- I will ask.
I installed the Auricaps & it made a significant change for the better. I may bypass them next- if so I will post pix. One thing to note about the Auricaps is that the wires are so large you will need to drill out the PC board holes- kind of a hassle; so you may want to consider another brand if you don't have much experience with this sort of thing.
I also added shiny black knobs as the gold is annoying to me. It looks so nice that the Mrs asked me to put the unit on TOP of the stereo cabinet. I got the knobs from Parts Connexion.
 

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Guys, I just wanted you to know that it is really tough going to cut through that foil to get rid of the grounding issue... use a very sharp, strong instrument to get it done.

I just purchased some EAR damping feet for the unit- I will install them and let you know if it helps the SQ.
 
Dared Ground Loops et. al.

Hi everyone,
Well the big question was: why did I do it? What made me tear apart a perfectly good sounding piece of gear in search for that audio grail?

The best way to explain it was that the sound was just "off" meaning that I could not put my finger on why I did not like prolonged listening to this unit. Having experience with ground loops in other gear, I decided to take the meter to the circuit board. And yes, I found what I typically did.

Pulling ground loops out is a simple thing to do once you really understand what they are and where they hide. WHY manufacturers build in ground loops into an otherwise excellent design, such as the Dared, is a mystery to me. The good news is that those with the right skills can transform a sow's ear into a silk purse.

I have updated the tube swap article to include the ground loop issue and one other I discovered while poking around: wrong values in the RIAA network. don;t get me started about stupid manufacturing mistakes but mine had one that is just inexcusable and points a finger at the quality control department.

So for those who want tips on "how to" without having to reinvent the wheel, contact me and I'll send you a copy of the whole series of tweaks, tube swaps, capacitor upgrades, RIAA fix, and ground loop fixes.
Cheers,

Philip Rastocny
philip@okstatealumni.org
 
I asked Phil about the ground loops and I am going to try to find this one this weekend and put in the Rusky .01 Teflon bypass caps. I will post pix:

"Next is the one on the big power transformer. I measured on mine that the ground wire connected to the PC board is redundant. Measuring from ground to the PC board before and after lifting this wire read continuous as the the measurement from the transformer wire to ground. I believe that was the last one"
 
My tube experience

I have dozens of tubes of the ax, au variety and rolled a bunch into the 7P. I had the best luck with Brimar in the preamp section. I tried Mullard, EI, Telefunken, MiniWatt, RCA, Sylvania, and Amperex- the best in my system were the Brimar. Accurate with deep bass to sparkling highs!
 
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OMG-
You guys need to bypass your caps, I have not heard bass like this before, clarity like this before or just crystal clear highs. You can see the 4 Russian Teflons and the 2 Vishay- this is exceptional!
I really should say that I have not heard anything in my system that sounds so good; some of my friends have better sounding preamps- however they spent four or five times more on them.
 
I just got the Dared MC-7P preamp; I am pleased with the sound... but not impressed. I see lots of room for upgrading here so I thought I would start a post to see what others have done with this nice little preamp.
First it responds really well to tube rolling- it is very responsive to NOS tubes.
Feel free to post your results with different tubes.

Second I popped the top and there are these huge yellow block shaped caps in it (1.0 value). I think they have to go! Has anyone had experience cap rolling with this preamp?

I am purchasing some Russian FT3's to try in my power amp, so I think I will get an extra set to try in the only place that I see room for this large cap in this cramped preamp.

I am looking forward to some interchange here so we can all make out preamps better!

Here are a few photos of the belly of the beast.

Hello guys, are you sure that all signal capacitors are changed? Aren't the two small blue capacitors (0,47µ) connected directly (via 100 Ohm resistor) to the output? And aren't the green ones in the middle connected between the anode of 12AX7 and the grid of 12AT7?

Greetings
Perry
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.