The new "My Ref" Rev C thread

[ClaveFremen]

Originally posted by schro20

Now, 1uF?! Come on! Just imagine how much lower you can push the phase shift at the bottom end if you go with a 10uF coupling cap!

Size does matter! Yep 10uF or bust!!!

peter

As for the value I'm sure you're right, it's the voltage rating that worries me...

It seems that higher the voltage, better the cap

The PHE426 is polypropilene 250V, the MMK is polyester 63V...

But a nice polyester: in parallel with a 4.7uF Mundorf MCAP Zn cleaned up highs and gave a better bass too.

[schro20]

Originally posted by ClaveFremen
It seems that higher the voltage, better the cap

The ApexJR cap is 250V and 10uF!

peter

[ClaveFremen]

Originally posted by schro20

The ApexJR cap is 250V and 10uF!

peter

But it don't fit and I want one that does...

In 22.5mm spacing I've found 4.7uF MMK 100V

On the first monoblock I'll try the 10uf MMK (I've only one left...) against PHE426 and if it's better I could give a try (and buy... ) also to the 4.7uF...

[schro20]

Originally posted by ClaveFremen
But it don't fit and I want one that does...

Gotcha!

Let us know how it goes (and do do a blind compare!)

peter

[Tony X]

Hi All,

Well, I wired the amp to-gether with care and hooked it up to a cd player using the bulb dimmer and .... nothing from neither left nor right.

Can anybody suggest a series of checks?

I don't know where to start.

Thanks in anticipation

[troystg]

Originally posted by Tony X
Hi All,

Well, I wired the amp to-gether with care and hooked it up to a cd player using the bulb dimmer and .... nothing from neither left nor right.

Can anybody suggest a series of checks?

I don't know where to start.

Thanks in anticipation

Pictures... That is the starting place.

Test AC voltage at the BR to see if it is getting ~24VAC...

[schro20]

Originally posted by Tony X
Can anybody suggest a series of checks?

The first thing I would do is carefully (painstakingly...) check that all the parts are where they are supposed to be and that all the electrolytic caps are connected with the correct polarity (as well as diodes and transistors). Then the more painful check: that the values or the components are correct relative to what they should be. In other words read off the rings of the resistors to make sure the right one is in the right slot. Though that's very painful. Likely checking that you have the correct supply voltages in the right places is a good thing to do before then. What about the LM318? Is it in there correctly?

Yes. Pictures would help with some of these questions.

peter

[AndrewT]

Hi,
one should get a brief dim flash at switch on when some smoothing is connected to the transformer.
Is the fuse blown?

[udailey]

Originally posted by Coreyk78
... wondering if there are any capacitor locations where it would be worth it to use some boutique caps?
Reason I ask is I have some muse and silmic II caps along with a fair sized collection of Russian PIO caps, K42-Y, K40-Y, and FT-1 teflons. ...

I have tried Silmics and my ears may be different but I much prefer the Panasonics. The Silmics leave that suffocating veil on the music to me. I love the PIO caps though and if I had thought of it I might have used my PIOs on the .22uf spots as many as would fit anyway. Top/Bottom/However you can get them in there.

If you guys havent tried out a pre for this yet I have a suggestion that TOTALLY turned the tables on this amp. I used GeorgeHiFi's Lightspeed Attenuator and it blows the alps I was using out of the water. I dont know why I am going to attach it to a B1, but I have a B1 missing a diode and a resistor. When Digikey gets here I am going to do the LightspeedEctomy and remove the lightspeed from its home as it is right now and then solder it onto my B1 and see what happens.
The MyRef does require about 10k and the Lightspeed gives it 7-8k depending on your LDRs you use in it. With 96dbSPL speakers I can crank it to about 12 oclock before scaring myself but I listen at only about 8oclock. Go read about it, come back, and let me know if you need matched pairs of LDRs. I bought 100 of them and now have 120 and have a lot of matched pairs. I was going to make a 24 band equalizer with them, but its just to much work and would require buying a lot more of the LDRs to get the right number of pairs at the right resistance.
http://diyaudioprojects.com/Forum/vi...8d41b6d668f8e1

Also pics of my boards, which I had to redo as I had a mistake on them. Redone and working flawlessly.

http://picasaweb.google.com/udailey/...eedAttenuator#

The Lightspeed is said to completely blow away any TVC attenuators and I have used metal film stepped switched attenuators, Alps, Radio Shack , General Radio Precision Wirewound, and B1 to power my amps and this is absolutely without doubt the best.
Uriah

[Tony X]

Thks replies so far.

I took a lot of care when inserting the components so as not to make mistakes. I am colour-blind so resistors were handled with special care. The dimmer (20 W) does flash for a fraction of a second - I suppose as the caps are charging. I also put in an LED which just lights up - but only just.

What I suspect the most is that there has been a short between the heatsink and the printed circuit on the underside of the board, altough it must be really bad luck for this to happen on the two boards at once.

I put a heatsink on the transistors while soldering.

The toroidals are rated at 24.5V, 230W.

I hope the attached photos are clear