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Dynaco t-70 tube amp?


Guest Steven1963

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Guest Steven1963

Yes, I can solder. I'll take some high res photos of the guts later today and send them to you.  Thanks for your help, Craig!

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Hi Steven, very cool acquisition. For what its worth I'll offer a small comment on your power tubes, which appear to be Shuguang. I have a set of monos that I do a bit of tube rolling with and ran a set of Shuguang Treasure KT-88's through (I know your set are 6CA7, and of course your amps lend their own unique character to a tube selection), but one observation on the Shuguangs I ran:  It took a LONG time to burn them in. I had about 150 hours on them before they began to settle and open up a bit. Prior to that they were (to my ear) base heavy and lacked definition. After that they did open up somewhat but I still felt they were a little "thick" in sound. I have had better results with some other tubes. "Better" to my ear anyway. They were very "present" and muscular in sound, soundstage was OK size wise, but again I was never thrilled with what I felt was a lack of detail (up to 200 hours or so anyway, when I rotated some other sets through). 

 

There are a lot of interesting and high performing NOS tubes out there, after your tubes (and ear) settle in on the current sound signature plug in another set of good tubes with those sweethearts and I bet they give you a little different character. I think there may be some options that give you a more airy and spacious sound than the Shuguangs.  . . . . . .YMMV of course.

 

But, boy, that is a nice buy. Very cool.

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Guest Steven1963
It took a LONG time to burn them in. I had about 150 hours on them before they began to settle and open up a bit. Prior to that they were (to my ear) base heavy and lacked definition.

 

Thanks!

 

This is what I am hearing.  The base is just so much more than what I remember from Heresy's. That, and I think the mids are toned down around 4 or 5db. Like I said, if I were blindfolded and didn't know these were Klipsch, I'd bet they were another brand.

 

Anyway, I just did a quick swap back to a more familiar receive (HK AVR 510) with the same song.  My ears weren't lying.  My original thoughts still hold:  I am hearing more base and more low mids (thick, as you said) and less highs and high mids, but cleaner there also. And what I called clarity earlier you called definition, I think we are talking about the same thing here.

 

Still lots of burn in-time with these and by the time I get them hooked into my Khorns they should be good and dirty.  

 

Craig, you've got me excited about some nice upgrades with this!  I don't think the wife is too keen about making changes to it since I 'just bought it,' she said.  But after I get moved and settled I will definitely be tinkering.  :D

Edited by Steven1963
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Guest Steven1963

I'm glad Craig's full-on on the case!

 

Me too!  It's nice to have a little help with this. I've always wanted to get into tubes but I don't have the first clue.  

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It took a LONG time to burn them in. I had about 150 hours on them before they began to settle and open up a bit. Prior to that they were (to my ear) base heavy and lacked definition.

 

Thanks!

 

This is what I am hearing.  The base is just so much more than what I remember from Heresy's. That, and I think the mids are toned down around 4 or 5db. Like I said, if I were blindfolded and didn't know these were Klipsch, I'd bet they were another brand.

 

Anyway, I just did a quick swap back to a more familiar receive (HK AVR 510) with the same song.  My ears weren't lying.  My original thoughts still hold:  I am hearing more base and more low mids (thick, as you said) and less highs and high mids, but cleaner there also. And what I called clarity earlier you called definition, I think we are talking about the same thing here.

 

Still lots of burn in-time with these and by the time I get them hooked into my Khorns they should be good and dirty.  

 

Craig, you've got me excited about some nice upgrades with this!  I don't think the wife is too keen about making changes to it since I 'just bought it,' she said.  But after I get moved and settled I will definitely be tinkering.  :D

 

 

Steven,

 

 Don't do it right away get a couple hundred hours on the amplifier and speakers first...I want this break in thing out of the way so I can dispel the myth ;) Yes this gear needs time to break in to come into its own. But the change is small.....Break in is never going to truly cure the comments being made. You might get used to what you are hearing and it grows on you... But break in is never going to have a pronounced effect.  

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We should do a nice thread on this....I think once were done you'll be shocked at the difference and I bet you won't spend more the $100 on parts.

cheapest 100$ you ever spent -

Edited by Randyh
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Guest Steven1963

Just wanted to throw out an update on what I am hearing.  If the guy was correct and the tubes had about 80hrs on them when I got it I'd say they have between 95-100 on them now.

 

Bass has evened out alot, not so overwhelming. I can hear more treble and the midrange is breathing alot better - getting more pronounced and they are starting to sound more like Klipsch, but clarity/definition is still missing - almost as if those frequencies are distorted and stepping on one another (think of an amp pushing it's limits). And strangely even though I didn't mention this before (because there was so much to mention, I suppose) it holds true throughout: midrange and treble tones sound lower...as if the notes have been tuned down.  

 

Perhaps that is what is meant by a warm sound?  I've never understood what was meant by that so maybe.

 

Anyway, Craig, yeah I'm not going to touch anything at least until I hook this amp up to the Khorns and hear it through them.  I know how my Khorns should sound, but not Heresy III's. That should be happening mid-April.  Until then I've got plenty of time to break in the amp, and the speakers if they are needing it too.

Edited by Steven1963
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this was a great buy!  I think you might benefit form some tube rolling, those chinese output tubes are the not the best choices out there for an ST-70.  burn-in should not really be a factor.  before soldering anything try swapping out the tubes for some russian or NOS tubes, there are lots of great EL#4 options out there, 6CA7 have not been my cup of tea buy YMMV.  see if that helps.  BTW do you know how to bias the thing?  T

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Guest Steven1963

Thanks!

 

Bias...no!  haha.  I still have to learn how to do that and maybe that's an issue?  Although, it is sounding much better!  I'm hearing things I didn't know were there even when I was listening to the same music through my Khorns! So that is promising and very exciting for me. Once I get moved and have it hooked up to the Khorns I can do a much better assessment sound-wise.

 

I'm definitely interested in the upgrades Craig has talked about, and I'm also interested in the rolling tubes.  When I get to that point I will be back to the forums for some advice like the Russian or NOS you mention.

 

It has been less than a year since I jumped back into music in a serious way.  In that time, I've bought and sold Lascalas, bought Khorns, an amp, pre-amp, equalizer, DBX sound processors, and now Heresy's and a tube amp.  I think it's safe to say I've been bitten. :rolleyes:

Edited by Steven1963
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Here are a couple of biasing links.  

The first from your amp provider (see page 40):

http://site.triodestore.com/NEWST70Instructions.pdf

This from another good source (page 11, ignore the battery part):

http://www.curcioaudio.com/st7_mnl.pdf

Bias should not make a huge difference in sound unless you are way off.  you google for some discussion about biasing an ST-70.

Let us know when you are ready to tube roll, lots of opinions around about best things to try.

Warm regards, Tony

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Steven,

 

My take on tubes also, as I just recently got into them. The warm sound is more to me like a richer mellowed sound, and is an aquired sound to get used to from SS.

 

The mids and highs are more defined, but toned down with "bite" and the bass isn't as much thumping or muddled as it is more in tune with the music. To me anyway, and with the amp I have.The more you play with speaker config and seating,the better the sound will be.

 

Glad you jumped on that amp. 

 

Jim

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  • 1 month later...

Welcome to the world of tubes Steven. A few things I've noticed with my Heresy 1's and ST70, though I haven't used them together yet, is that the Heresy speakers are very "picky" about the room and placement. My pair have zero bass in my living room, using a Denon AVR, but if I move both pieces to the Master Bedroom, it's much better. The Heresy's, in my basement work shop, using a mid 1980's Technics receiver, have so much bass that I actually turn it down a bit. My ST70 is very near stock, I have the PAS3 tube preamp also. To me, it is critical to have a tube preamp to get the very best from the amp. A good solid state preamp does well too, just not quite as good as tubes. I did connect the Heresy's to my mid/late 60's Zenith Allegro Console and it sounds heavenly, different, but every bit as good as the tube rig.

I'm fortunate to have a number of incredible Old Stock/NOS tubes, including the originals that came stock in the Dynaco gear, Mullard XF2 EL34's for power and a Mullard F31 GZ34 Rectifier. These tubes, in my opinion, are THE BEST in the ST70. I've tried just about every current production EL34 and 6CA7 as well as the ultra rare GEC KT77, Siemens/RFT EL34, Early Tesla EL34, RCA and Sylvania big bottle 6CA7. The biggest problem to getting these jewels now is price, with some examples, GEC KT77, approaching $400 per tube. My current production favorite in the ST70 is the JJ 6CA7. It's not a true Beam Power Tetrode, but sounds excellent, none the less. Another current tube that sounds real sweet, is the Winged C EL34, made in St. Petersburg, Russia, though the cost per tube is approaching good used Old Stock at about $100 per tube.

Tube rolling can get very expensive, but there are still some good deals out there for Old Tubes. I find the history of tubes, and their manufacture, to be almost as interesting as listening to the music they reproduce. There's not a day in recent memory, that I haven't listened to or worked with tubes in some capacity. Probably because I play guitar, repair and service tube guitar amps and Hi Fi. Lol. I love this stuff. Enjoy!

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Guest Steven1963

I am finally in my new house and I have the Klipschorns mated with the Dynaco.  Honestly, I am disappointed. But I think it has more to do with room acoustics than the speakers and the amp. The Khorns are about 16 feet apart in a room that runs at least 30 feet deep (great room/kitchen combo), with 9 ft ceilings. The real issue I think is that the speakers are sitting a bit recessed into alcoves, with a fireplace in the middle, and the ceiling lowers to 8 ft. This configuration is causing the bass to be too thick and in some instances booming with hanging notes in the lower octaves.

 

I thought the room as close to ideal as possible and while I did have concerns about the alcoves, I was unprepared for the amount of influence they are having on the sound. Some options are to pull them out of the alcoves to be flush as if the room was more square. But that presents the problem of one back edge of the speakers not being on a wall at all.  No harm in trying it. :D

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And here's a link to a site that has a lot of info and parts for the Dynaco stuff. I'm not affiliated in any way, but I've heard some of the gear, and mods, they're outstanding. I'm considering replacing the driver board in my ST70 with theirs. It has individual bias for each power tube, and means you can use unmatched tubes, which makes it easier to get Old Stock singles at a good price. As well, it uses much more common 12AU7's instead of the difficult to find 7199's.

http://www.tubes4hifi.com/home.html

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The base is just so much more than what I remember from Heresy's. That, and I think the mids are toned down around 4 or 5db. Like I said, if I were blindfolded and didn't know these were Klipsch, I'd bet they were another brand.
Steven,

The H IIIs are much smoother and more balanced than the first generation Heresy. Always thought they sounded too hot in the mids. My older son has a pair, and I like my H IIs a lot better. I would imagine (and from what I have heard others report) Klipsch has done a great job on the HIIIs.

 

Nice deal with the ST-70 clone as well. Once it's broken in and Craig helps out, I'm sure you will like it.

 

Bruce

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I am finally in my new house and I have the Klipschorns mated with the Dynaco.  Honestly, I am disappointed. But I think it has more to do with room acoustics than the speakers and the amp. The Khorns are about 16 feet apart in a room that runs at least 30 feet deep (great room/kitchen combo), with 9 ft ceilings. The real issue I think is that the speakers are sitting a bit recessed into alcoves, with a fireplace in the middle, and the ceiling lowers to 8 ft. This configuration is causing the bass to be too thick and in some instances booming with hanging notes in the lower octaves.

 

I thought the room as close to ideal as possible and while I did have concerns about the alcoves, I was unprepared for the amount of influence they are having on the sound. Some options are to pull them out of the alcoves to be flush as if the room was more square. But that presents the problem of one back edge of the speakers not being on a wall at all.  No harm in trying it. :D

I'm of the belief that, "When all else fails, try anything. It's better than doing nothing at all."

Good luck dialing your system in.

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Another current tube that sounds real sweet, is the Winged C EL34, made in St. Petersburg, Russia
The plant has been shut down for a year. Nice tubes, though, that's what I have for my ST-70.
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