Another ST-70 question

organorgan Posts: 5,022
edited May 2004 in 2 Channel Audio
OK, here's another question for the ST-70 experts. My ASL is messed up right now and found an ASL repair center not too far away that will fix the problem and perform internal mods. The mods will run me about $160CDN which isn't bad and he said there's a big improvement over the stock version. After talking about the ASL with the technician, somehow we started talking about the ST-70. He told me that he had worked on many ST-70 and didn't recommend I keep it stock for the restoration. He said that the 7199's need to go. He said the best mod was one provided by Audio Research many years ago but I can't find it anywhere. Anyway, the person who's going to restore it for me said he could modify the original board to accept different types of signal tubes.

So my question is about the 7199 tubes. Should it be a go or no go??? I don't mind paying $30 each for the 7199 but I'm more concerned about the sound quality. He said the board could be modded to accept 6922 signal tubes which are better than the 7199.

Thanks

Maurice
CD Player: Original CD-A8T
Receiver: Harman/Kardon HK3390
Speakers: Polk Audio RT1000p
"I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
Post edited by organ on

Comments

  • dcarlsondcarlson Posts: 1,740
    edited April 2004
    Don't know but... I'll be interested to hear which way you go. Stock/non stock.

    Are you planing on getting it fixed soon?
    SDA-2a, Anthem Pre-2L, Anthem Amp 1, MF A324 DAC, Rotel RCD1070

    Senn HD650 Cardas, Mapletree Audio Ear+ HD2, Kimber KS1030, Bel Canto DAC2, M-Audio Transit, Laptop.
  • organorgan Posts: 5,022
    edited April 2004
    Yeah. If everything goes well, I should have her playing again in about a month and a half. Everything will be replaced with better parts except the transformers. He said if the circuit board is still good it will stay. He's also going to re-chrome the chassis. I'm thinking about getting increased filter capacitance as well.

    If I do get the circuit board modded, the JAN Philips and Sovtek 7199's will be for sale.

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • Tour2maTour2ma Old School Posts: 10,176
    edited April 2004
    Sorry, can't help you maurice... There are about as many opinions on tweaking 70's as there are 70's owners. I've chosen to stay stock, or as stock as possible.
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    "Death doesn't come with a Uhaul." - Dennis Gardner
  • organorgan Posts: 5,022
    edited April 2004
    That's cool. A lot of people like to keep it stock to retain its value. I don't plan to sell this amp, EVER! I'll ask about the mods on audioasylum. If you guys are interested in the answers I can post them here.

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • dcarlsondcarlson Posts: 1,740
    edited April 2004
    Sounds cool.

    I put the new RCA's in mine last night. I didn't have time to give a good listen and I won't have a chance to do so until next week.
    SDA-2a, Anthem Pre-2L, Anthem Amp 1, MF A324 DAC, Rotel RCD1070

    Senn HD650 Cardas, Mapletree Audio Ear+ HD2, Kimber KS1030, Bel Canto DAC2, M-Audio Transit, Laptop.
  • organorgan Posts: 5,022
    edited April 2004
    Awesome. Did you have to increase the size of the holes on the two boards holding the RCA's? I had to do that with mine. Did you manage to get them further apart?

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • dcarlsondcarlson Posts: 1,740
    edited April 2004
    It's sort of temporarily set up for now. I used the mono/stereo switch hole for one and drilled a larger hole into the plastic piece for the other. Not the best looking but it works. ;)

    Next up is the power cord. I'm still debating on the IEC inlet. It would make things so much easier powercord wise. I'll probably do it next week.
    SDA-2a, Anthem Pre-2L, Anthem Amp 1, MF A324 DAC, Rotel RCD1070

    Senn HD650 Cardas, Mapletree Audio Ear+ HD2, Kimber KS1030, Bel Canto DAC2, M-Audio Transit, Laptop.
  • Tour2maTour2ma Old School Posts: 10,176
    edited April 2004
    maurice,
    Please post a link to your Asylum thread here, and we'll follow a long.
    More later,
    Tour...
    Vox Copuli
    Better to remain silent and be thought a fool, than to open your mouth and remove all doubt. - Old English Proverb

    "It's easy to get lost in price vs performance vs ego vs illusion." - doro
    "There is a certain entertainment value in ripping the occaisonal (sic) buttmunch..." - TroyD
    "Death doesn't come with a Uhaul." - Dennis Gardner
  • organorgan Posts: 5,022
    edited May 2004
    No luck on AA. I'll try dynaco-doctor.com and post a link if there's any response.

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • BrianomaticBrianomatic Posts: 58
    edited May 2004
    organ

    Congrats on your Dynaco ST-70 purchase. I have owned the solid state Dynaco 400 and 416 amps and the PAT 5 preamp since the late 70's. I have modded some and had others do mods over the years.

    I always wanted to get my feet wet in tube equipment and your thread is making me want to jump-in. Tube equipment has a sound of its own versus SS just as vinyl versus CD's. I remember studying tube technology in college (feeling old now) with all the biasing requirements and such. As you will learn, the tube equipment require regular maintenance in regard to keep the tubes operating within their design bias along the load line of the tube's characteristic curve.

    Anyway, you had mentioned the Audio Research mod and I seen this on Ebay. It may be of some interest to you.

    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=39783&item=3094340597&rd=1

    Regards

    Brian
    Music:
    Polk SDA SRS
    Dynaco 416 (2)
    Dynaco Energy Storage System
    Van Alstine Transendence Pat 5
    Van Alstine Transendence CD
    Marantz 2270 Receiver

    Home Theater:
    Onix Rocket 750 (4)
    Onic Rocket RSC200
    Onix Rocket RSS300 (2)
    Denon 3803 Receiver
    Denon 1600 DVD player
    Infocus X1 Projector
  • organorgan Posts: 5,022
    edited May 2004
    Hi Brian,
    Thanks a lot for the link. I will call the guy doing the restoration and ask if he could perform the AR mod if I provide the booklet. If he will, I'm going to purchase it. Thanks.

    "As you will learn, the tube equipment require regular maintenance in regard to keep the tubes operating within their design bias along the load line of the tube's characteristic curve."

    I've learned quite a bit about tube equipments when it was working. Well, it wasn't perfect when I first got it last summer. I had to replace the quad cap and bias supply. The amp started to go down hill in January or Feb. Can't wait until she's all good again. You're right about the maintenance. It's more work than SS equipments but the reward the amp gives you is really something else.

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • organorgan Posts: 5,022
    edited May 2004
    I think I found the problem. I started to wiggle the coupling caps around and a few of them were loose. The solder had gotten soft over time. I removed all 6 and re-soldered. So far so good. 1hr and no red plates yet:). Oh she sounds soooooo sweet:). I still plan to get it restored in about a month.

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • dcarlsondcarlson Posts: 1,740
    edited May 2004
    Congrats...

    I've been agonizing over a tube pre or speakers. A much as I would love to get new speakers I think a pre would be the wiser choice.
    SDA-2a, Anthem Pre-2L, Anthem Amp 1, MF A324 DAC, Rotel RCD1070

    Senn HD650 Cardas, Mapletree Audio Ear+ HD2, Kimber KS1030, Bel Canto DAC2, M-Audio Transit, Laptop.
  • organorgan Posts: 5,022
    edited May 2004
    I sure hope it was the coupling caps. It's been on for many hours and still working fine. The Svet's/JAN/Mullard are really singing.

    A tube pre made a very big differece to me. Probably as big as adding a tube amp. I think going with a tube pre first is a better shoice. Your tube magic will increase 100%. Why don't you try out the 'Foreplay'? $150 and can be completed in a single night or two. www.bottlehead.com

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • dcarlsondcarlson Posts: 1,740
    edited May 2004
    Good luck with it. :)

    I've read about the Foreplay. Are there any other decent kits out there?
    SDA-2a, Anthem Pre-2L, Anthem Amp 1, MF A324 DAC, Rotel RCD1070

    Senn HD650 Cardas, Mapletree Audio Ear+ HD2, Kimber KS1030, Bel Canto DAC2, M-Audio Transit, Laptop.
  • organorgan Posts: 5,022
    edited May 2004
    Don't know any ther kits but there are a lot of upgrades available for the foreplay on the bottlehead website. They say it's best to build it normally first and then add the upgrades.

    Which pre amps are you looking at right now?

    Maurice

    *edit* I just checked tubestore and they have a new batch of 7199 tubes. No pics or brands mentioned. It just says "NOS assorted brands" for $29 each. Cheaper than the JAN/Philips. The JAN/Philips are still $30 at triodeelectronic
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
  • dcarlsondcarlson Posts: 1,740
    edited May 2004
    None in particular just yet. I've got more reading to do.

    I've read countless good things about the ST-70 and the foreplay pops up every now and then.
    SDA-2a, Anthem Pre-2L, Anthem Amp 1, MF A324 DAC, Rotel RCD1070

    Senn HD650 Cardas, Mapletree Audio Ear+ HD2, Kimber KS1030, Bel Canto DAC2, M-Audio Transit, Laptop.
  • organorgan Posts: 5,022
    edited May 2004
    OK, I'm sure it was the coupling caps. It was on all day and night until 6:30am and no problem at all. I only turned it off when I went for my smoke breaks. I still can't believe how good this amp sounds. Soundstage is HUGE and so much power for the Klipsch. AAAAAAAH:D

    Yeah, quite a bit of people use the foreplay with their ST-70.

    If you decide to try new power tubes give the EH6CA7 fat bottle a try. Less bloom and sweetness than SED but more detail, air, extension and power. Seems to dig lower too.

    Now I'm thinking about which caps to replace the stock with. I've been doing a lot of reading and a lot of people say the coupling caps make a difference. The oil-in-paper are more mellow, lush and less detailed. The most popular ones are the big orange caps.

    Maurice
    CD Player: Original CD-A8T
    Receiver: Harman/Kardon HK3390
    Speakers: Polk Audio RT1000p
    "I would rather have a cup of tone than an ocean of power" **Dr. Harvey Rosenberg**
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