[mrdon]

OK, after a little listening this AM, I must recommend the Elna Cerafine 220uf over the 220uf BG FK and instead use. The Cerafine provides superior bass definition and slam. The BG in comparison presents the bass as bloated and tubby. I know that BG's are the bees knees in audio but my ears tell me something different in this application.

BTW, if anyone wants to try the BG FK 200uf cap in their VALAB, I now have a slightly used one available. PM me and let's make a deal.

 

[Bill Allen]

Mrdon-

Blackgates take in the order of 400 hours; some say even 1000 hours, before they are fully broken-in. They also need to be powered on at all time for optimum performance. (I won't use them except in circuits that remain on). There really is no reason to shut off the Valab DAC, I leave mine powered up all the time.

Given the above conditions the Blackgate's are an ideal match with the Valab. Give your BG 220uf more time before you jump to a conclusion. Blackgate's in the power supply are all about recovery speed. They have no peers.

By the way, nice clean job on your Valab mod, I really like the silver wire touch. In fact you have inspired me to go back and mod my late 2008 Valab Dac.

I noticed you used BG FK's on the DAC chips, it’s a brutal break-in period and trust me ... you're not there yet! (That's why I pre-plan and install all my Blackgates at one time, I refuse to go through multiple BG break-in's).

I would also look seriously into removing or bypassing those Blackgate coupling caps you installed. I know in the past I promoted the BG's as coupling caps but I am going to have to renege on that in light of current findings. The Kiwame I/V resistors are a nice combo with the BG couplers but they may be a bit soft if you switch to film couplers.

 

[PatOMalley]

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif Mrdon- Blackgates take in the order of 400 hours ... By the way, nice clean job on your Valab mod, I really like the silver wire touch. In fact you have inspired me to go back and mod my late 2008 Valab Dac. I would also look seriously into removing or bypassing those Blackgate coupling caps you installed.

I can vouch for that breakin time. I use 4.7uF BG and bypass them at output. You gotta wait. The bass is something can pull of with no sweat. They are just closed in as you move into the lower midrange up. Congested. But for bass they are aok.

Regarding that silver wire .... I be thinking you having your wire precap. I used your picture as a guide. Then I went back and noticed from anotehr pic that I really should be picking up[ where the trace really starts to feed to output. Have another look at my picture. I wish I could remember who else posted a picture of the output rewire ...

 

[rhodes54]

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif rhodes54, The Dexa's "Dropout Voltage" is: 2.00V So it is a 2v difference and should work.

Sorry for the delay of my answer. I didn't notice that the dropout voltage was mentioned on the website. Thanks for looking it up for me.
By the way: My Toroid transformer gives 10.5V AC and that will be even more when converted to DC so there won't be a problem feeding the Dexa 7808.
The LT1084 will be replaced by the Dexa next week as I didn't manage to get the heatsink of the board with only having a hand vacuum pump available. Luckily we have a professional desolderstation at work so I'll give it another shot next week.

Quote:

Originally Posted by PatOMalley /img/forum/go_quote.gif Looks like I am stuck using the Dexa for the board only[7805]. But that's what I was thinking to do anyway to feed the DIR9001 with better power to cut down on jitter. The only things is that some EPI speakers showed up here today that need recapping. And my tonearm needs replacing. I am dragging my feet on the transformer thing.

Did you already replace it for the Dexa 7805?

 

[rhodes54]

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif It just didn't compare to my modded Valab. Right away Tony looked at me and said "sounds like electrolitic's coupling caps". Yep, that's what it sounded like to me too! (Tony will be moving on to Mundorf Silver/Gold's which he uses in this 26 Preamp. Good Choice)! Tony started with "N's" and then upgraded to the "NX Hi Q's". In light of this comparison i would not waste my time using Blackgate as coupling caps in the Valab Dac. If you are looking to save money and also fit film caps inside the Dac, I'm with Pat, simply bypass the stock coupling caps. My suggestion is buying the best .22uf bypass film caps you can afford, with Jupiter's or Mundorf Silver/Gold's being "my" top choice's. Finally when you get your Dac sounding just the way you want. Then by all means get thy modded Valab Dac to the Cryo Lab.

I have my Valab modded with Mundorf Silver/Gold and that's definitely a great choice. If Tony likes lots of details and a huge soundstage than Mundorf is an excellent choice.
I will do a test with Silver/Gold/Oil next week (5,6uF) as I used those in the crossover of my Audio Physic speakers. I expect an even greater detail and bigger soundstage with the Silver/Gold/Oil's.

By the way, your "man cave" looks great! I had to choose between a studio or listening room as those dutch houses ain't that big.

I chose for a studio as I'm still earning some 'coins' with it and still is my other hobby.

 

[mrdon]

Quote:

Originally Posted by Bill Allen /img/forum/go_quote.gif Mrdon- Blackgates take in the order of 400 hours; some say even 1000 hours, before they are fully broken-in. They also need to be powered on at all time for optimum performance. (I won't use them except in circuits that remain on). There really is no reason to shut off the Valab DAC, I leave mine powered up all the time. Given the above conditions the Blackgate's are an ideal match with the Valab. Give your BG 220uf more time before you jump to a conclusion. Blackgate's in the power supply are all about recovery speed. They have no peers. By the way, nice clean job on your Valab mod, I really like the silver wire touch. In fact you have inspired me to go back and mod my late 2008 Valab Dac. I noticed you used BG FK's on the DAC chips, it’s a brutal break-in period and trust me ... you're not there yet! (That's why I pre-plan and install all my Blackgates at one time, I refuse to go through multiple BG break-in's). I would also look seriously into removing or bypassing those Blackgate coupling caps you installed. I know in the past I promoted the BG's as coupling caps but I am going to have to renege on that in light of current findings. The Kiwame I/V resistors are a nice combo with the BG couplers but they may be a bit soft if you switch to film couplers.

Thank for your kind complement concerning my mods.

I know all the arguments about BG's break-in time, but again I am hearing a vast difference b/t the 220uf Cerafine and the 220uf BG FK. Yes, the Cerafine is broken-in, but will more break-in time increase the speed and power of the BG that I am now getting from Cerafine? Again, I realize this goes against modding tradition and your own personal experience of your mods, but in my VALAB that Cerafine is a vast and I mean vast improvement. Nevertheless, I have taken your advice and am leaving my VALAB for the next two weeks or so to take care of those other BG's. Shh...don't tell my wife who pays the PSEG bill.

Concerning the BG-NX HiQ couplers...I had great results from them in my Cambridge Audio 640P phono stage mods (a shout out to PatOMalley and our brethren over at Vinyl Engine.) Yes, I would have liked to go with coupling film caps in my VALAB, but since I am currently unemployed spending $20+ on a quality film cap verses $2.50 for a BG-NX HI-Q is a no brainer. Plus, anything is better than the stock YUCK coupling caps that smeeeeaaaaarrr the sound. If I had my druthers and the $$$ funds, I would have liked to hear how Auricaps or Soniccaps worked - again these are caps I have good experience with in the past. Nevertheless, I do have some small .01uf film caps in my arsenal of parts. In your opinion, do you think I should bypass the BG-NX HI-Q's? I have read on the WWW that this is not necessary and in some cases causes more problems. Based on experience, any contrasting opinions?

In that same vein, I have always liked the sound of Kiwame resistors. Metal films tend to sound too sterile to my ears and Carbon comps although rosy sounding are in my experience unpredicable - carbon films are a good compromise especially the high-quality, tight spec'd Kiwames. Well actually they are KOA Speer (the OEM for Kiwame) from Mouser

 

[mrdon]

Also, I asked this above...does anyone know what is the suggested output voltage at pins 6 and 8 of the TDA1543? This output voltage can be adjusted. I have set mine b/t 3.8 and 3.9 VDC, but is this the optimal voltage?

 

[PatOMalley]

The LT1084 is a 5v rectifier so I think I can use Dexa's 5v to replace both regulators because both are LT1084 in my machine.

Why are you taking the heatsink off? I thought you could affix the regulator right onto it.

Quote:

Originally Posted by rhodes54 /img/forum/go_quote.gif Did you already replace it for the Dexa 7805?

 

[dubai2000]

The latest updates:

Replaced the stock 10uF smt caps next to the 1543s with 100uF Oscons and bypassed the filter section between I/V resistors and RCA sockets. The latter was one of the big steps forward: a lot more dynamic and even greater transparency. I think for the time being I'm done as there is no harshness at all - just an incredibly musical DAC (feed by USB).

 

[mrdon]

Quote:

Originally Posted by dubai2000 /img/forum/go_quote.gif The latest updates: Replaced the stock 10uF smt caps next to the 1543s with 100uF Oscons and bypassed the filter section between I/V resistors and RCA sockets. The latter was one of the big steps forward: a lot more dynamic and even greater transparency. I think for the time being I'm done as there is no harshness at all - just an incredibly musical DAC (feed by USB).

So the signal is now going directly from pins 6 and 8 on the TDA1543 and directly out to your preamp? I assume your preamp has DC blocking caps on its input?

 

[dubai2000]

Not quite: I took the signal off the 330R resistors directly into the output caps and from there straight to the RCA outs.

 

[PatOMalley]

Quote:

Originally Posted by dubai2000 /img/forum/go_quote.gif Not quite: I took the signal off the 330R resistors directly into the output caps and from there straight to the RCA outs.

Can we see a picture of that?

 

[r8833]

Pat,

It's easier to do on 09 version because of the layout. This is way I bypassed filters .. end of 390r - 4.7 cap - rca

Rich

 

[Bill Allen]

Gentlemen,

With a DAC as simple as Valab every little thing you do will change the sound. Think of what you do in the analog output path as EQ or adding Bass & Treble. My Hi-Fi system is already finely tuned; I am simply looking for resolution. If you system “needs something” then my I/V Resistor and Coupling Cap choice may not be to your liking. It’s all about balance. Let me repeat that …. “IT’S ALL ABOUT BALANCE”

The power supply mods are all about dynamic’s and speed, remember there is no “analog” power supply in the Valab Dac, just an I/V resistor and coupling cap. Balance, balance, balance! Change one, it affects the other. Bypassing the simple ferrite bead analog filter network and idle resistors may sound great with your system but can make another system unstable and diminish sound quality. The safe bet is to leave it alone ... but if you are adventurous...

mrdon- the L/R analog output voltage is set by the value of the I/V resistor. The blue variable bias resistor you are turning is not for adjusting output voltage, it’s for adjusting "current" (mA) to the reference voltage. (Yes it will change the L/R output voltage slightly) In a normal 1543 DAC this Bias resistor would be used to adjust the output current for maximum dynamic range of op-amps. (I.E. Bias) There are no op-amps in the Valab so its function remains questionable in my book. Kind of like the human appendix, serves little or no function. However mine is staying in unless it gets infected.

Einstein's maxim - "everything should be made as simple as possible, but no simpler. ...

 

[Bill Allen]

I show pictures of soldering to the DAC chip side of the I/V resistors to bypass the filters. (Captions at the bottom of pictures)

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