Looks like the interest in these new Eletro Harmonix KT90`s has kicked off again just as i`ve clocked over 200hrs on them. So i`ll start a new thread this ones getting full. I said i would report back on how their behaving.
Let me first tell you that they are 1 inch taller than my Sovtek Kt88, this is no small valve, the total recommended max plate dissipation for the plate is 54 watts that is very good, a good friend of mine also ordered 10 off and as with all new valves he gets he gives them a heavy test, he told me he put 580v on the plate and wound them up to 150ma current draw for 15mins to see what would happen ,and said they the plates did`nt even get the slightest bit red. That sounds dam good to me.
Now for the sound, stunning thats all i can say, i`ve had Svets 6550 and Sovtek Kt88 their good but do`nt compare to these, i own a pair of B&W801 s2 Matrix a ***** of a speaker to drive well. My amp rig is 4 box affair, 2x amps 2x power supplies with 4 output valves per channel i always listen in triode The 6550`s and the kt88`s could just drive them properly, but the KT90`s were so much more powerful, and controlled that you thought that someone had doubled the amount of output valves.
Yet these valves are as sweet as any 6550 or kt88 that i`ve heard on my system. One other bonus is that they put out halve the heat of the 88 or 6550`s do`nt ask me why the heater current draw is the same and all other parameters are also the same, must be the size of the massive plate structure, get rid of the heat more efficiently.
Cheers George
Let me first tell you that they are 1 inch taller than my Sovtek Kt88, this is no small valve, the total recommended max plate dissipation for the plate is 54 watts that is very good, a good friend of mine also ordered 10 off and as with all new valves he gets he gives them a heavy test, he told me he put 580v on the plate and wound them up to 150ma current draw for 15mins to see what would happen ,and said they the plates did`nt even get the slightest bit red. That sounds dam good to me.
Now for the sound, stunning thats all i can say, i`ve had Svets 6550 and Sovtek Kt88 their good but do`nt compare to these, i own a pair of B&W801 s2 Matrix a ***** of a speaker to drive well. My amp rig is 4 box affair, 2x amps 2x power supplies with 4 output valves per channel i always listen in triode The 6550`s and the kt88`s could just drive them properly, but the KT90`s were so much more powerful, and controlled that you thought that someone had doubled the amount of output valves.
Yet these valves are as sweet as any 6550 or kt88 that i`ve heard on my system. One other bonus is that they put out halve the heat of the 88 or 6550`s do`nt ask me why the heater current draw is the same and all other parameters are also the same, must be the size of the massive plate structure, get rid of the heat more efficiently.
Cheers George
Hi there George.........Have you wound up the current on the KT90's to get them stewing glowing red........If so do the anodes glow equally on either side, and roughly the whole length ?
Did you get the KT90 tubes already <run-in> ? The reason I ask is because I'm having big troubles with Svet 6550B's......It's impossible to set the quiescent current to a set value even with stabilised B+ and neggy bias volts. Even with bogey heater volts they seem to take a very long time warming up to stabilise the characteristics...any such observations in the KT90 ??
rich
Did you get the KT90 tubes already <run-in> ? The reason I ask is because I'm having big troubles with Svet 6550B's......It's impossible to set the quiescent current to a set value even with stabilised B+ and neggy bias volts. Even with bogey heater volts they seem to take a very long time warming up to stabilise the characteristics...any such observations in the KT90 ??
rich
Rich, it was a friend of mine that did punishing test, he wound them up to 150ma current with 580 plate volts , if you work that out that`s 87watts per valve, mate that`s some serious watts of dissipation for one valve and it still did`nt get red after 15 mins, he said he was`nt going to push his luck any further. Mine are running 520 plate and 78ma, that`s cruzing for these valves.
And as far as mine went with bias stability, no problems they held steady bias from the get go and yes the were brand new never run.
BTW i got them from New Sensor in New York i`ve forgot to tell every one, and i believe they now own Sovetek in Russia and that`s where these come from EH is just a division of Sovetek i believe.
Cheers George
And as far as mine went with bias stability, no problems they held steady bias from the get go and yes the were brand new never run.
BTW i got them from New Sensor in New York i`ve forgot to tell every one, and i believe they now own Sovetek in Russia and that`s where these come from EH is just a division of Sovetek i believe.
Cheers George
Hi,
Nope...You're confusing a few things here.
New Sensor, the people behind the Sovtek brandname, bought the rights to use the Svetlana brandname in the U.S.
BTW, expect the EH KT90 to look like this:
Before I make any bold claims, let's wait and see how they measure.
Cheers,
Nope...You're confusing a few things here.
New Sensor, the people behind the Sovtek brandname, bought the rights to use the Svetlana brandname in the U.S.
BTW, expect the EH KT90 to look like this:
Before I make any bold claims, let's wait and see how they measure.
Cheers,
Attachments
Re Hmmm.
Hi,
50W max.
You should...I've known these for years and they truly rock.
If you like the sound of live music, as I think you do, you owe it to yourself to audition these....
They can come pretty close and this becomes pretty obvious especially when driving ribbons, which you also happen to like.
Pssst....It's still a EL509/519 in disguise you know...Not that it matters...
Just don't marry them to 12AT7s ot AU7s....Don't ask, I have enough enemies as it is.
Cheers,
Hi,
50W max.
You should...I've known these for years and they truly rock.
If you like the sound of live music, as I think you do, you owe it to yourself to audition these....
They can come pretty close and this becomes pretty obvious especially when driving ribbons, which you also happen to like.
Pssst....It's still a EL509/519 in disguise you know...Not that it matters...
Just don't marry them to 12AT7s ot AU7s....Don't ask, I have enough enemies as it is.
Cheers,
Steve i`ve never listened to the 802, but from what i know the 802 is better if you can`nt control the bass of the 801`s, if you can control the bass of the 801, i believe they are a great deal better.
And Frank the valve that you have posted is so different to what i have it`s not funny, http://www.diyaudio.com/forums/showthread.php?s=&threadid=24313&perpage=15&pagenumber=4
For a start the plates of yours have square holes, mine are round and the top of the plate structure is totaly different, just have a look and see.
And i have it on good authority that mine are made by the Sovtek/ Electro Harmonic factory in Russia the thing that you posted is a http://www.kolumbus.fi/flait/techzotic/sv5092.htm
and is called a EL509 mk2
Which is so different to what i have it`s not funny, look at the 2 web sites that i`ve posted and tell me their the same, so wrong.
Cheers George
And Frank the valve that you have posted is so different to what i have it`s not funny, http://www.diyaudio.com/forums/showthread.php?s=&threadid=24313&perpage=15&pagenumber=4
For a start the plates of yours have square holes, mine are round and the top of the plate structure is totaly different, just have a look and see.
And i have it on good authority that mine are made by the Sovtek/ Electro Harmonic factory in Russia the thing that you posted is a http://www.kolumbus.fi/flait/techzotic/sv5092.htm
and is called a EL509 mk2
Which is so different to what i have it`s not funny, look at the 2 web sites that i`ve posted and tell me their the same, so wrong.
Cheers George
SY...... Hi there.......my grid leak for 6550B is 68K per tube. I could go lower but the law of diminishing returns prevails. That's a heavy driving load for the preceeding stage.
You may be on to something here........but difference between 50K/68K ain't much, although KT88's can go considerably higher with these values. I had designed for 88's.......but it looks that 90's may take their place. As the B+ rating for KT90's follows the 88 ball park i.e 800V, the vacuum status must be clearly better than 6550's.
George..... it looks like slam driving the KT90 can do more damage to the output tranny than it'self....One of the tests for well constructed tube is symmetrical anode heating with no grid pecularities.
any others'
rich
You may be on to something here........but difference between 50K/68K ain't much, although KT88's can go considerably higher with these values. I had designed for 88's.......but it looks that 90's may take their place. As the B+ rating for KT90's follows the 88 ball park i.e 800V, the vacuum status must be clearly better than 6550's.
George..... it looks like slam driving the KT90 can do more damage to the output tranny than it'self....One of the tests for well constructed tube is symmetrical anode heating with no grid pecularities.
any others'
rich
Rich, my mate does`nt use an amp to carry out these rude tests on his valves he`s got some kind of test bed that he uses, he`s a manufaturer, and sells a lot of amps here in Sydney and down in Melbourne, you may of heard of him, his name is Elson Silver and his amps are called Cymer, he`s very well respected here in Australia. (he was very impressed with measurements that he got with the EHKT90`s that`s why he rang me and told me)
This is only one of the tests he performs on any new valve he gets. he always sacrifices one or two valves for testing out of a batch that he buys of any new valve, before he passes the rest on to his customers in his amps. and the re-orders in big quanities. This is why he has such a good name here in Australia for reliability with his products, customers never have any troubles when they buy a Cymer valve amp.
Cheers George
This is only one of the tests he performs on any new valve he gets. he always sacrifices one or two valves for testing out of a batch that he buys of any new valve, before he passes the rest on to his customers in his amps. and the re-orders in big quanities. This is why he has such a good name here in Australia for reliability with his products, customers never have any troubles when they buy a Cymer valve amp.
Cheers George
Yeah, 68K is not unreasonably high. But apparently too high for this tube in its youth.
I wonder how it would work driven by a direct-coupled source or cathode follower? That would take the load off of the previous driving stage and allow the grid impedance of the 6550B to be lowered. Same with a grid choke as a load, but I personally prefer followers at this sort of voltage swing.
I wonder how it would work driven by a direct-coupled source or cathode follower? That would take the load off of the previous driving stage and allow the grid impedance of the 6550B to be lowered. Same with a grid choke as a load, but I personally prefer followers at this sort of voltage swing.
Alright Frank, what is the point?
I see a report of the EH standing 80 watts of plate dissipation, and have looked at the two tubes and don't think they are the same, or even close. To assume that no knowlege or expertise of EI would be put towards the development of the original, is ridiculous. As is the claim that it is a copy of an existing design. The KT90 plates don't look anythig like the EL series you keep claiming.
I hate to be the one arguing this, but your continued assertion that the KT90 is a re-bottled/based EL509 is wearing quite thin.
I hopt that a further expansion of the KT90 is done, something on the scale of an 813 or 13E1. A 6JS6C with a 120 watt plate rating would give me cause to really smile.
regards,
Douglas
I see a report of the EH standing 80 watts of plate dissipation, and have looked at the two tubes and don't think they are the same, or even close. To assume that no knowlege or expertise of EI would be put towards the development of the original, is ridiculous. As is the claim that it is a copy of an existing design. The KT90 plates don't look anythig like the EL series you keep claiming.
I hate to be the one arguing this, but your continued assertion that the KT90 is a re-bottled/based EL509 is wearing quite thin.
I hopt that a further expansion of the KT90 is done, something on the scale of an 813 or 13E1. A 6JS6C with a 120 watt plate rating would give me cause to really smile.
regards,
Douglas
Thanks Douglas, i thought i was alone on this one.
Frank the pictures of mine are the Electro Harmonix production version, go to the New Sensor web site they are there for all to see.
http://www.turnstyle.com/nsc/catalog.asp?raster=DBD7.0x6AADB57CB72FF613.F10D.0.2970&cat_id=1728
Expensive @ $58us but if you have and account they are considerably cheaper, alas they are out of stock at the moment.
Honestly Frank sometimes i do`nt think you can see the forest through the trees, and i`m trying to be as polite as possible here.
Love and Kisses George
Frank the pictures of mine are the Electro Harmonix production version, go to the New Sensor web site they are there for all to see.
http://www.turnstyle.com/nsc/catalog.asp?raster=DBD7.0x6AADB57CB72FF613.F10D.0.2970&cat_id=1728
Expensive @ $58us but if you have and account they are considerably cheaper, alas they are out of stock at the moment.
Honestly Frank sometimes i do`nt think you can see the forest through the trees, and i`m trying to be as polite as possible here.
Love and Kisses George
SY....hi there...the bias business........okay there’s loads of 6550 circuits around using 100K grid leak res upwards......(crazy in fixed bias) using wimpy driver circuits but that’s how it is. My AC driver performance is slam class A performance soaking 30mA per side (triode configured pentodes);...... I blow the trumpet so I like to hear good definition, implies amp THD performance at full power way below 0,5% at 10Khz...so I’m ruling this bias/driver problem out.
I agree that 6550’s as per RCA/GE spec suggests 50K grid leak in fixed bias...I’ve never had the same sounding amp from using cathode follower drivers.... I find there is a serious overhang with this configuration i.e isn't a <Miller effect dump driver> if I can use this term.
rich
I agree that 6550’s as per RCA/GE spec suggests 50K grid leak in fixed bias...I’ve never had the same sounding amp from using cathode follower drivers.... I find there is a serious overhang with this configuration i.e isn't a <Miller effect dump driver> if I can use this term.
rich
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