Using Kt-120's in a Traynor YBA 3A

[pbman1953]

Months back, with the help of the forum, I converted a Traynor YBA- 3A from El34  to 6550's. Total success.




My question is if the Traynor could handle the Tung Sol  KT- 120. I have them in a Sunn 2000s and they work fine.


I'm just curious on the the Traynor




Thanks

[shooter]

could handle the Tung Sol  KT- 120

look at both datasheets, look at the schematic to see if there's enough info to calc I or Pdiss, then see how that jives with the 120.  If that's good, hunt down tranny specs to see if they can handle it, then if all is good, bias and play

[TubeGeek]

I have thought about doing this to my yba3a custom that I also converted to 6550's a few years back.  The transformers are huge, so I doubt there would be any problems running 120's.

[Ritchie200]

I know Ed has played around with the 120 quite a bit.  If I'm not mistaken, I think he said he liked the KT88 better?  Maybe he will jump in.  I've also heard from other folks that the 120 sounds kind-of like a 6550.  I'm not a big fan of the 6550, but I know there are folks who are.  Not that I'm pushing my KT88 agenda here   Just wanted to throw this out in case someone's still undecided.  Any of these tubes in quantity are not a cheap investment!

Jim

[pbman1953]

Here's a little more fuel to the conversation.  The Traynor already has 4-Tung Sol 6550's and sounds fine. I have a Sunn 2000s with the 4- KT-120's in it now. The one thing I've found is that the Sunn has more balls with 6550's. The 120's are sooo smooth that Sunn is kind of boring. Don't get me wrong it's still amazing but it's like playing through a Macintosh instead of a bass amp.  I'm thinking of swapping sets from amp to amp only because the Sunn will get it's grunt back and the Traynor already has built in grunt. I thinking the combination of the Traynor's grunt and the 120's smoothness might be a cool match.


This should be interesting.

[pbman1953]

Anyone want to chime in?


Here's a spec sheet for the KT120. Next post will be for a 6550

[jjasilli]

I think the only choice is to try.  KT-120 is usually for hi-fi, so there's probably little practical experience here.  Re guitar amps, except for the Reply above, I've only heard of them being used in the Fender 400-PS, where they seem capable of taking the voltage-current abuse offered by the vintage GE 6550's.  See, http://timeelect.com/400-histy.htm


Nothing wrong with tube rolling.  Also note, they draw more heater current, so check for adequate heater voltage.

[Ritchie200]

Ditto for the Major. I know someone who used them in that unfriendly environment and they did just fine. That's who told me they sounded like a 6550 in that application.   After a while he went back to some vintage KT88's.

Jim

[pbman1953]

Maybe I should try and set the set and go for another set of 6550 or KT-88

[Ed_Chambley]

I have an amp I built for a friend we changed from KT88 to KT120 to see how well it was.  The comment of smooth is certainly warranted until pushed.  They run 2 tubes Push Pull in a UL design amp.  Changing the PI tube to a 12At7 from a 12Ax7 helped guitar.  My friend plays a large stage and has the ability to run them hard.

You can hear an extension in Bass on guitar and it is very nice.  Harmonics are thunderous and even with plate voltage around 560 they seem to be loafing along.  Big Clean sound, but hard to duplicate the KT88 when pushed.  Even looking with a scope the KT120 keeps a nice sine wave when the KT88 is squaring off.

I have built 2 and was just asked to make a third.  I too prefer the 6550 for bass and of course my Leslie cabs.  The kt120 in my amp which V1 is a EF86 is very nice for a small bass rig,  The overtones from the preamp complement bass very well.  Changing the same amp to KT88 and using a single coil has some nice jangle and very authoritative bottom.  Plug in a Humbucker Equipped guitar and the strong mids appear.  One would think Volume would be too much, but it is not as loud as a Push Pull EL34, but feels stronger.

It is the feel these big bottles give that nothing else can do.  I absolutely love mine and use it with  2 12 cab.  When I built the one for my friend who plays a large place I thought I would have no use for it, but even at manageable volumes the EF86 tone delivered clean is really cool.

My 2 cents.  BTW, I have not been able to kill a KT120 or a Chinese Valve Art.  The new Gold Lions have a great distortion but I toasted a pair within 6 months.  I have some more now, but I am enjoying the KT120's for now.  HUGE HUGE sound, very full and not offensive even when cranked a tad.

[Ritchie200]

The new gold lions appear to a regular rebranded new sensor kt88 which if you put them next to their 6550 they look identical on the inside.  I don't know what I'm gonna do when my =C= will finally give it up.  About 20 years ago I did the great tube roll and it was expensive and not fun.  I had tubes that only lasted a couple of hours to ones that sounded horrid.  (Chinese and kt90 for extreme reference...) Thanks for chiming in Ed!

Jim

[pbman1953]

Update-




I think the KT’s will be fine.  Before I installed the KT’s I ran the amp at idle but on and the transformers with the 6550’s were cold then approach cool, They never warmed up. After that I removed the 6550’s and placed in the KT’s. As is no change, transformer temp wise,  and  the amp has been running for at least 15-20 minutes in the on position.
 
For biasing I have a Bias Rite from Weber VST. As far as a bias point I was always told to take a range of 60% - 70% of the tubes dissipation spec which is 60 watts. At the moment here’s what I get for a settings:
 
 
The formula I use is  volts (Vp) x  Current (Ik)
 
A-     40
B-     37.2
C-    37.6
D-    39.5
 
 
I may leave it at that. Many people go for a mid point and I’m a hair over on one tube.
 
 

[Ritchie200]

After you play it for a while, I'd like to know what you think about those tubes in that amp.  What brand are you using?

Jim

[pbman1953]

Jim


Since people were home, I really couldn't crank it. But I could tell that the power reserve will beat out the Tung Sol ( New Sensor) 6550. The sound was full and reaction time and dynamic range will be scary.


Traynor YBA- 3A ( The stock EL 34 version)


Tubes- Tung Sol KT-120 ( New Sensor)

[traynor]

I rebuilt a Traynor YBA Mark 2 into a 2 ch Ampeg B15N using 5691 and KT120 and it sounds great.

[pbman1953]

Very Nice!

[alsucral]

Hello there

It is freezing summer here in Finland....so it is time for another amp build.

I´ve been gathering components and indo etc for Traynor YBA 3 a super custom special with 6kg6 magnoval valves.

I´m still looking and verifying information of PT and OT for this amp, do thay have these in nowadays Hammond catalogue, or do you have any suggestions for a good replacements.

thanx. Arto from Finland

[Ritchie200]

Welcome Arto!  I'm sure one of the guys will chime in on your information but wanted to welcome you to the site. Also go Kimi and Bottas!


Jim

[alsucral]

Thanx for welcome. I did my studies for elctronics in mid 80s. I was working after school hours at the local cable tv company. After school I worked at workshop, repairs and sales etc audio stuff, studio and professional kind. After that I´ve been into studying my amps and making them sound better. Been building clones for my own use.

[Jazzbass_5]

 Does anyone have the schematic for any of these YBA-3 CUSTOM SPECIAL tube mods? 

[pbman1953]

Does anyone have the schematic for any of these YBA-3 CUSTOM SPECIAL tube mods?

For the "Super" or the Custom Special?

[Jazzbass_5]

Does anyone have the schematic for any of these YBA-3 CUSTOM SPECIAL tube mods?

 Non super, 1972 w/master volume. 100watts - 160watts
I'm looking for the mods for this attached schematic.
Thanks!

For the "Super" or the Custom Special?

[pbman1953]

Here's a good link-


http://www.0rigami.com/vb/models.html


After lookup the YBA-3A

If you want to go for 6550's you need to upgrade the grid resistors but even not a good idea.

If you want to go for KT120's , better to add a filament transformer to take the stress /heat away from the PT. For mine I stayed with 6550's but with my Sunn 2000s I installed the transformer to use the KT's. They are one of the best sounding big bottle tubes. I didn't think of trying the 150's, too big and the 120's were fine


If you are going for the resistor option , ask the group here because they may have some additional improvement suggestions