I have a matched quad set of KT88's. Any problems with sticking them on my ST70 (Bob's version)?, and, any benefits at all?, thanks.
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sKiZo
Jim McShane
Bob Latino
mhardyman
peterh
Dave_in_Va
polarflux
11 posters
KT88's in the ST70?
polarflux- Posts : 49
Join date : 2010-02-12
Location : Alaska
Bob will advise you to bias them to 500 miliamps, but no. Provides a little more authority on the low end but the effects to the rest of the range will depend on the tubes you are using.
Guest- Guest
interesting, just put them in, now keeping in mind that these are brand new, I am getting quite a bit more at the high frequency, for a given song, had to knock the treble back a bit. Low end seems about the same, maybe a touch more.
I'll keep them in for a while now and see how the settle in.
I'll keep them in for a while now and see how the settle in.
Dave_in_Va- Posts : 443
Join date : 2013-04-02
Location : Mid. VA
I tried two sets of KT 88's (Russian and Chinese) in my VTA ST 70 and ended up preferring EL 34's (new Valve Art, NOS Sieman's and NOS Mullards).
peterh- Posts : 1833
Join date : 2012-12-25
Location : gothenburg, sweden
It's ok.MontanaWay wrote:I have a matched quad set of KT88's. Any problems with sticking them on my ST70 (Bob's version)?, and, any benefits at all?, thanks.
You will see lower impendace that might improve bass control ( depending on speakers)
I settled for JJ 6550 which was an improvement from valve art el34
mhardyman- Posts : 14
Join date : 2012-04-15
MontanaWay wrote:I have a matched quad set of KT88's. Any problems with sticking them on my ST70 (Bob's version)?, and, any benefits at all?, thanks.
Have been using the Genalex KT-88 reissues for several years now. A very nice sounding tube. Even, nicely extended highs and very well controlled bass. Bear in mind that the preamp board will do more for tone control than the power tubes. My final setup employs an NOS Tungsol 12AU7 in the center position and the sides are new EH 12BH7s.
This current set powers a pair of DCM Timewindows that I bought new and are power hungry yet revealing speakers. They have never sounded so good. I have tried the SED EL34 and the JJ EL34 in this amp. They were ok but... underwhelming in comparison to the KT88. It feels like the KT88 tube has more range and punch. I like it.
Bob Latino- Admin
- Posts : 3262
Join date : 2008-11-26
Location : Massachusetts
In the VTA ST-70 KT88 output tubes do have more output at the frequency extremes - the very bottom and the very top of the frequency range. This may be a benefit IF you have speakers or other associated equipment that are "soft" on the top end. It may, however, be a liability if your speakers are a little "bright" to begin with. KT88's also have the liability of costing twice as much as an EL34. They will, however, last longer than an EL34 in the VTA ST-70 which offsets somewhat their increased cost.
EL34's are the traditional output tube used in ST-70 type amps. They are cost effective and are really good sounding tubes especially in the mid bass and vocal range.
In the VTA ST-70 you can use EL34, 6L6, KT66, KT77, KT88 or 6550 output tubes. NOTE - do not use the last two output tubes mentioned in a STOCK ST-70 unless you have an upgraded power transformer. They draw more current and can put an already overworked ST-70's original PA-060 power transformer "over the edge".
Bob
EL34's are the traditional output tube used in ST-70 type amps. They are cost effective and are really good sounding tubes especially in the mid bass and vocal range.
In the VTA ST-70 you can use EL34, 6L6, KT66, KT77, KT88 or 6550 output tubes. NOTE - do not use the last two output tubes mentioned in a STOCK ST-70 unless you have an upgraded power transformer. They draw more current and can put an already overworked ST-70's original PA-060 power transformer "over the edge".
Bob
Cubdriver likes this post
Guest- Guest
well I've been running the KT88's for quite a few hours now since yesterday afternoon and yes, there is a noticeable difference between them and the KT66's.
I loved the KT66's over the EL34's, I am starting to like the KT88's over the KT66's, they do sound, to my ears, even clearer and crisper again, pretty much on all music I played so far, ranging from classic, jazz, blues to rock, I had to knock the treble and bass back a bit on the preamp.
Be interesting to see how they settle in over the coming weeks.
I loved the KT66's over the EL34's, I am starting to like the KT88's over the KT66's, they do sound, to my ears, even clearer and crisper again, pretty much on all music I played so far, ranging from classic, jazz, blues to rock, I had to knock the treble and bass back a bit on the preamp.
Be interesting to see how they settle in over the coming weeks.
Jim McShane- Posts : 237
Join date : 2011-10-19
Location : South Suburban Chicago
polarflux wrote:Bob will advise you to bias them to 500 miliamps, but no. Provides a little more authority on the low end but the effects to the rest of the range will depend on the tubes you are using.
Is that correct?? 500 ma!! Wow, even for four tubes that would be 125 ma. per tube, and with 430 plate volts that's 53 watts dissipation!
Bob, if you read this - is that correct?
Bob Latino- Admin
- Posts : 3262
Join date : 2008-11-26
Location : Massachusetts
Hi Jim,
I am pretty sure that Polarflux meant 50 milliamps per each output tube - not 500 milliamps ... 500 milliamps is 10 times the recommended bias current ! Some of the confusion probably comes from the fact that the recommended bias VOLTAGE is 500 milliVOLTS or .500 volts (1/2 volt) per each output tube.
Bob
I am pretty sure that Polarflux meant 50 milliamps per each output tube - not 500 milliamps ... 500 milliamps is 10 times the recommended bias current ! Some of the confusion probably comes from the fact that the recommended bias VOLTAGE is 500 milliVOLTS or .500 volts (1/2 volt) per each output tube.
Bob
Jim McShane- Posts : 237
Join date : 2011-10-19
Location : South Suburban Chicago
Bob Latino wrote:Hi Jim,
I am pretty sure that Polarflux meant 50 milliamps per each output tube - not 500 milliamps ... 500 milliamps is 10 times the recommended bias current ! Some of the confusion probably comes from the fact that the recommended bias VOLTAGE is 500 milliVOLTS or .500 volts (1/2 volt) per each output tube.
That's more like it!
fedoragent likes this post
sKiZo- Posts : 1530
Join date : 2013-04-01
Location : Michigan USA
Smokin! 
On a totally unrelated note ... board running slow the last couple days? Only way I can get a page to load is if I tell it to stop loading ... Seems like it's hanging up loading ads or some such. This is the only site giving me problems ... Anyone else?
PS ... that's using Chrome ... I can't even get it to load in Firefox ...
On a totally unrelated note ... board running slow the last couple days? Only way I can get a page to load is if I tell it to stop loading ... Seems like it's hanging up loading ads or some such. This is the only site giving me problems ... Anyone else?
PS ... that's using Chrome ... I can't even get it to load in Firefox ...
pmarcin- Posts : 128
Join date : 2009-01-20
Age : 76
I'm using Firefox on a MacBook. It loads full page ads, which you have to page out.Ugh. It just started doing this.
peterh- Posts : 1833
Join date : 2012-12-25
Location : gothenburg, sweden
I have flashblock installed as add-on in firefox. Takes care of many annoying ads.pmarcin wrote:I'm using Firefox on a MacBook. It loads full page ads, which you have to page out.Ugh. It just started doing this.
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
No issues here with Chromium on Linux. There was that chocolate bar ad that ate up half the screen but it was fixed a coupla weeks ago.
If you'e on Verizon DSL they've been doing upgrades up and down the line from Coos Bay Oregon to Libby, Mont., maybe in your neck of the woods, too. We were down completely for 28 hours. Actually had to make conversation with my wife. Turns out she's a nice person.
If you'e on Verizon DSL they've been doing upgrades up and down the line from Coos Bay Oregon to Libby, Mont., maybe in your neck of the woods, too. We were down completely for 28 hours. Actually had to make conversation with my wife. Turns out she's a nice person.
Guest- Guest
deepee99 wrote:No issues here with Chromium on Linux. There was that chocolate bar ad that ate up half the screen but it was fixed a coupla weeks ago.
If you'e on Verizon DSL they've been doing upgrades up and down the line from Coos Bay Oregon to Libby, Mont., maybe in your neck of the woods, too. We were down completely for 28 hours. Actually had to make conversation with my wife. Turns out she's a nice person.
Guest- Guest
I use Safari, no problems here. We don't have the best ADSL2+ speeds here, since we're so far from the distribution hut, we're actually a 'special' customer of 3 Rivers because of our distance, they've been trying out new gear with us. Hopefully fiber optics are not that long away to get here, they have it on HWY287 and the distribution hut, but thats 4.2 miles away!....hence our 'special' status......
corndog71- Posts : 840
Join date : 2013-03-19
Location : It can get windy here
Ghostery is another good add-on ad-blocker.
deepee99- Posts : 2244
Join date : 2012-05-23
Location : Wallace, Idaho
corndog71 wrote:Ghostery is another good add-on ad-blocker.
I'll see if I can hack that in to Chromium, and let you know. We're less than a half-mile from the main Verizon FIOS line, but still running coax to the house.
Back on topic, the Gold Lion KT-88s are incredible tubes, if properly matched. Just don't grab the glass end first when you're pulling them out of the box. They don't work very well after that even when reassembled with Super-Glue.
pmarcin- Posts : 128
Join date : 2009-01-20
Age : 76
I installed the add-ons. They appear to work, but now I have other issues.
pmarcin- Posts : 128
Join date : 2009-01-20
Age : 76
One of the extensions blocked the Javascript for the 'edit' window at bottom of the page. I disabled it.
pmarcin- Posts : 128
Join date : 2009-01-20
Age : 76
OT: Two extensions block this window. Nuts, they add security. Just overzealous.
Guest- Guest
MontanaWay wrote:I use Safari, no problems here. We don't have the best ADSL2+ speeds here, since we're so far from the distribution hut, we're actually a 'special' customer of 3 Rivers because of our distance, they've been trying out new gear with us. Hopefully fiber optics are not that long away to get here, they have it on HWY287 and the distribution hut, but thats 4.2 miles away!....hence our 'special' status......
I spoke too soon. Getting to load the forum pages has become painfully sloooooooooooooow.....started yesterday......every other web site loads just fine...
fedoragent- Posts : 57
Join date : 2013-09-14
Bob Latino wrote:In the VTA ST-70 KT88 output tubes do have more output at the frequency extremes - the very bottom and the very top of the frequency range. This may be a benefit IF you have speakers or other associated equipment that are "soft" on the top end. It may, however, be a liability if your speakers are a little "bright" to begin with. KT88's also have the liability of costing twice as much as an EL34. They will, however, last longer than an EL34 in the VTA ST-70 which offsets somewhat their increased cost.
EL34's are the traditional output tube used in ST-70 type amps. They are cost effective and are really good sounding tubes especially in the mid bass and vocal range.
In the VTA ST-70 you can use EL34, 6L6, KT66, KT77, KT88 or 6550 output tubes. NOTE - do not use the last two output tubes mentioned in a STOCK ST-70 unless you have an upgraded power transformer. They draw more current and can put an already overworked ST-70's original PA-060 power transformer "over the edge".
Bob
Bob,
Is this still your assessment for those that have the original PA060? Can one decrease the bias down to .400 or .350 to lessen the change of.....PA060 Chernobyl?
Thanks,
FG.
Bob Latino- Admin
- Posts : 3262
Join date : 2008-11-26
Location : Massachusetts
fedoragent wrote:Bob Latino wrote:In the VTA ST-70 KT88 output tubes do have more output at the frequency extremes - the very bottom and the very top of the frequency range. This may be a benefit IF you have speakers or other associated equipment that are "soft" on the top end. It may, however, be a liability if your speakers are a little "bright" to begin with. KT88's also have the liability of costing twice as much as an EL34. They will, however, last longer than an EL34 in the VTA ST-70 which offsets somewhat their increased cost.
EL34's are the traditional output tube used in ST-70 type amps. They are cost effective and are really good sounding tubes especially in the mid bass and vocal range.
In the VTA ST-70 you can use EL34, 6L6, KT66, KT77, KT88 or 6550 output tubes. NOTE - do not use the last two output tubes mentioned in a STOCK ST-70 unless you have an upgraded power transformer. They draw more current and can put an already overworked ST-70's original PA-060 power transformer "over the edge".
Bob
Bob,
Is this still your assessment for those that have the original PA060? Can one decrease the bias down to .400 or .350 to lessen the change of.....PA060 Chernobyl?
Thanks,
FG.
FG,
The original Dynaco ST-70 came out in 1959. Some of these 350,000 original Dynaco ST-70 amps are now 60+ years old and have an undersized original power transformer that is hanging on by a thread ! Just my opinion but > KT88 and 6550 output tubes draw more current than EL34 output tubes. Personally, I wouldn't risk using an original Dynaco ST-70 (with the original Dynaco power transformer) with KT88 output tubes.
Bob
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