Preamp update suggestions...

organ
organ Posts: 4,969
edited December 2009 in 2 Channel Audio
Ok, sometime this month, I will be bringing in one of my fav pre amps for an update, maybe mods if any looks like it would improve performance.

The pre is a Golden Tube Audio SEP-1. I absolutely dig the sound! It's about 15years old and I want better parts in there.

It is pretty much a mini SET amp acting as a pre-map. Single 6DJ8/6922 tube, one triode section/channel out to two transformers. Very interesting design in a tube pre amp. I really like the airy and lush sound it produces. But would like to add more weight to the sound if it can be done. Will increasing the power supply caps value help?

Also all the caps will be replaced with better ones. Any suggestions on brands of capacitors? I don't want to spend a fortune. Also, I like the tonal balance as it is, so I don't want caps that would make something more lush or warm than it already is. I wouldn't mind more HF extension but don't want my mids to get brighter. Is there a brand of caps out there known to do what I'm looking for?
Post edited by organ on
· Share on FacebookShare on Twitter

Comments

  • Face
    Face Posts: 14,340
    edited September 2009
    Copper Duelunds.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
    · Share on FacebookShare on Twitter
  • organ
    organ Posts: 4,969
    edited September 2009
    Thanks Face. Are they expensive?
    · Share on FacebookShare on Twitter
  • Face
    Face Posts: 14,340
    edited September 2009
    Define expensive.

    The small values comparable to other brands of similar quality. The larger sizes are much more expensive.

    What's in there now?
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
    · Share on FacebookShare on Twitter
  • organ
    organ Posts: 4,969
    edited September 2009
    I mean no more than $20/ea. for the small value caps.

    ok, these might be the PS caps... Not sure because there is another section to the power supply that is enclosed and I don't have a screw driver with me. But there are 4 black caps (can type), each are 200V/220uF. There are also three 16V/680uF each nearby. I see 9 red Wima caps throughout the circuit board. The 4 larger ones are closest to the tube. Coupling caps maybe? Two are very large compared to the others. There are also other caps around the board that are not labeled.

    My dealer has to mod the output stage somewhere because I want to use this pre with my Digital amp. But there is some hum when I use it on any SS amp but silent on all tube amps. There is a pair of 600 Ohm output Load resistors by the output transformers. I think Increasing this value should do the trick.
    · Share on FacebookShare on Twitter
  • Face
    Face Posts: 14,340
    edited September 2009
    The large values are PS caps. The Wima caps are probably your coupling caps. Wima makes a good cap for the $, Mcintosh uses them in their amps. You may want to consider going with new Wima caps if you don't want to change the voicing much.

    Here's a link to a very thorough cap comparison: http://www.humblehomemadehifi.com/Cap.html
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
    · Share on FacebookShare on Twitter
  • organ
    organ Posts: 4,969
    edited September 2009
    Thanks for the link. That was an interesting read.
    The Wima in the pre looks pretty much like the ones pictured. Not sure if they're different from the older Wima. But might as well change them. They must be over 15 years old already. I'm going to spend some time with the pre and decide if I want to keep the original voicing.

    Thanks again for the help.
    · Share on FacebookShare on Twitter
  • ben62670
    ben62670 Posts: 15,969
    edited September 2009
    I like the Auricap line. They are at your price point, and I have heard them in a few pieces of good gear. They are what I am going to be using in my tube venture.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben
    · Share on FacebookShare on Twitter
  • F1nut
    F1nut Posts: 50,565
    edited September 2009
    The standard for PS caps has been Black Gate, but they are out of business and it's getting hard to find any now. I understand Panasonic makes a good PS cap, but I haven't tried them.

    You should consult with Jeff Glowacki, the owner of Sonic Craft.
    Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."

    President of Club Polk

    · Share on FacebookShare on Twitter
  • zingo
    zingo Posts: 11,258
    edited September 2009
    I've used Ruby Gold for my tube PS caps before and they were great. Not real pricey, but a nice upgrade from stock.
    Jake
    · Share on FacebookShare on Twitter
  • organ
    organ Posts: 4,969
    edited September 2009
    Thanks for the help guys. I will keep all your suggestions in mind. I spent some time listening to it last night and I think I wouldn't mind trying a different flavor of caps.

    I'll let you guys know what I go for when I bring it in.
    · Share on FacebookShare on Twitter
  • organ
    organ Posts: 4,969
    edited December 2009
    Thanks again for the help guys. It's back and sounds better than ever.
    The circuit was modified and they kept the Wima caps in there, but everything else changed. The left side that is enclosed is the power supply, it was beefed up but not shown in the pic. The pot was changed to a stepped att. The output imp has been changed to make this pre super friendly with my current amps. There is a battery in the circuit now. Perhaps I should 'battery roll'? lol. The result exceeded my expectations. I'm really diggin the sound. I've been rolling some 6DJ8/6922 for the past few days. Tube fun!

    Sorry, I don't have the before pic of the circuit but it's quite a difference after the mods. I've also included associated equipments and a pic of the rig.
    · Share on FacebookShare on Twitter