Preamp Modifications

[tmazz]

For common parts like this digikey can ship 1st class mail, which is cheaper than mouser UPS.

For coupling I like the Jantzen Superior Z and Silver Z. They sound good and not too expensive. I avoid bypass caps.

For cheap coupling caps Vishay MKT1813 are pretty good for the money. http://www.vishay.com/docs/26013/mkt1813.pdf

Wow Rich, making 2 AM posts? 

Looks like you are trying to take over my vampire shifts. 

[rollo]

   We replaced Auricaps in two amps so far with the Alexandras. Only $90 for the pair [ .1 ]. Not even a contest. Just ordered Cast versions for preamp and Amps. BTW they are not re branded Jensens. Confirmed that with the distributor.
      You may consider ESC caps. Lower ESR than Panasonic or Muse. When the Cyber 211 was redone Scot from S&G Custom Sound who did the work suggested them over the others. Dynamics out the ying yang.
      One bit of advice if I may. When choosing tube coupling caps take in consideration what tube brand is used. You do not want to use a cap that fights the sonics of the tube. Meaning if the tubes character is say bright do not use a V-Cap. If dark do not use PIO.
    Learned that lesson during the Cyber mod. If we used the NOS RCA 211 then the V-cap was a great match. Not with NOS GE 211 though. Russian PIO were a better match.
     You may also consider Audio note Silver RCAs at $18 a pair.  Silver over pure copper. Have fun.



charles

[Face]

   We replaced Auricaps in two amps so far with the Alexandras. Only $90 for the pair [ .1 ]. Not even a contest. Just ordered Cast versions for preamp and Amps. BTW they are not re branded Jensens. Confirmed that with the distributor.

     You may also consider Audio note Silver RCAs at $18 a pair.  Silver over pure copper. Have fun.

I agree that Auricaps are nothing special.  My current favorite coupling cap are Claritycap MRs, although Duelund isn't bad either. 

As for the RCAs mentioned above, I don't believe they're copper based...especiall at that price.  Take a look at every other gold plated brass jack and they all look exactly like those mentioned, but a different color.  For a copper based jack that won't break the bank, check out Vampire.  http://www.soniccraft.com/products/connections/rca/chassis/vampire_cm1fcb.htm 

[rollo]

   Another RCA choice to consider is CNC if you desire all copper. Me, it would be all silver with the AI.
    When I purchased them parts Connection said they were silver over copper. Maybe I was misinformed. Now I have to know. 


charles

[rpf]

You might also try Jupiter HTs for coupling caps. I've used them in 2 DACS and really like them. In one they replaced Auricaps (original). Huge difference. The Jupiters are far more resolving and tonally accurate but also convey more harmonics.

They're of course much more expensive than Auricaps but much less than Dueland Alexanders.

[DaveC]

I put these in the final stage of my Aikido's PS and they make a HUGE difference!

http://www.partsconnexion.com/capacitor_film_clarity_tc.html

With the larger electrolytics, maybe bypass them with some film caps, especially if they are cathode bypass caps, this makes a big difference. I used Clarity ESA caps for this in my SET amp at 1.5 uF. They make ESA caps in 250V, which are much smaller and less expensive than most film caps, good for 'lytic bypass...

Also, the AI RCAs are silver over brass, no way are they copper at that price. I've heard others say they sound good though. I went with DH labs copper RCA jacks when they were 1/2 price at partsconnexion. Unfortunately, copper RCA jacks aren't cheap.

[rollo]

Well I was misinformed non magnetic I guess means brass.  .
   Mike you got me off my chair with this topic. have been thinking about eliminating the selector switch as only one input is needed. To make a long story short whoopee do do. Bypassed switch directly to board and no going back. Less noise, more clarity a bit more slam.
    Next up the attenuators.The Loesh & Weisner Pre uses Elna pots. Could use a bit more flexibility in control. Those 48 step babies sound attractive. I would love to get the Penny and Giles however my bank robbing skills need work.
    Interesting note in discovering silver hook up wire in the preamp. I thought I did not like silver. WRONG!!
    Mike you started this thread for the AI now I'm the journey. Thanks I never would have found out the BIG difference had by removing the selector switch. Duelund hook up wire ? Penny & Giles ?? Coupling caps ??? I'm forked !! Thanks a lot.



charles
   

[topround]

I don't know how much room you have in your preamp but the Shallco switches with resistors for $340 from Percy sounds like the way to go for me if I have the preamp I was taking to my grave.

I have used Vampire RCA's and like them, they sound good and don't cost a lot and are high quality as well.
Pure copper....does anyone make pure copper RCA's?
Remember this is going to be a project on a budget, no Vcaps, no pure copper RCA's no, Shallco stepped attenuators and certainly no Black Gates. I want to take a decent budget preamp and see what it can become with better parts, and Charlie if I can get some Chokes in there I will because chokes are cheap, at least the Hammond ones!
Remember when I cryo this thing it just may go bye bye!!

Coupling caps....that is always a good way to start a fight.
Regarding Duland...if I was to use deuland it would have to be the CAST other wise there are so many other great sounding caps to choose from.

I like Auricaps, they don't do everything but what they do well they do very well, I was wondering about the new AuricapXO's, though about giving them a try.

Modding....its back in style

[DaveC]

For reasonably priced coupling caps also check out Feastrex's new Urushi caps. I won a pair at RMAF and for $60 they sound really good, very neutral and clear. My RelCap PCU copper foil caps were a bit better, but for 2x the price. I'd get the Urushis over any other coupling cap near it's price range.

[BobM]

On a budget I think it is hard to beat Sonicaps. They are transparent and do not color the music, but they are not the choice if you are looking for something to beautify things.

[Response Audio]

Here are a few of my "personal opinions".

Coupling caps - my favorites are Clarity MR, V-Caps and Duelund. By the way, Duelund caps are made by Jensen to Frederick's specs. That's why they even say Jensen on the caps. No secrets being revealed.
I have always liked AuriCaps but now find their prices put them in competition with some other very good options. they use to be a great value.
SoniCaps are the cleanest capacitors available for the money. It you want a "no capacitor" sound at a great price, SoniCap is the one. The Gen 2 sounds very much like AuriCaps for a fraction of the cost.

Wiring- I personally like and prefer solid core Silver. Silver has gotten a bad rap over the years and my conclusion is because it wasnt given a fair shake. Like anything else in audio, the application and whole picture is more important than any one piece. A puzzle is worthless if you are missing a few pieces.

RCA jacks- Cardas is among the best in my opinion. CMC also makes some very nice pieces. Audio Note is nice but over priced. WBT.... Way over priced but another great product.

Power supply caps- prefer poly whenever possible. The Panasonic ED is my preferred electrolytic.

 When changing capacitors in the power supply, an all too often overlooked but critical aspect is that your B+ will very likely change and sometimes well out of its tolorable limits. Changes in DCR and/or capacitance WILL change the final B+ output. This must be taken into consideration whenever making any changes in the power supply. The best thing to do, if you don't have a schematic with voltage listed, it to take measurements before making any changes so you know where you need to be when your done.  Don't forget the power supply wiring.

Tube sockets - use Teglon whenever possible. Again, my opinion. Parts Connexion has some economy Teflon units that are very good.

Well, I guess that's enough for now. Play it smart and you can have a very good upgrade for a reasonable outlay of cash and when your done, you have the pride of doing it yourself.

[richidoo]

Good info there, Thanks Bill!

[rollo]

   OK then. Installed solid silver hook up wire in phono section. So far no complaints. Not thin or bright.
    The new solder joints and wire now have some playing time to evaluate.  Removing that selector switch has brought more to the table then expected. The improvement in clarity and detail is quite impressive. I thought it might be an improvement of some sort. Just did not expect such obvious results.
    Next up are Deulund Cast .1 coupling caps [ two pairs ]. Then get rid of the Cornell Dubier  caps with Solen as per the original design.
    The Genrad power supplies need some loving care from John Weisner. So before any money is spent on caps the power supplies need some love as they are very old.



charles

[topround]

Volume controls have arrived

[rollo]

  We have lift off.


charles