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Traynor YBA-200 Tube Upgrade

#21
BassmanPaul said:
Do I own this particular amp? - not anymore I don't, I tried one for a short while, didn't like it so it went. When it comes to safety I am very passionate...

The idea of someone with no knowledge of what they were doing possibly coming into contact with the voltages inside this class of amp simply terrifies me.

Paul
Click to expand...

Paul,

Great point - and something that I think many of us discount when glibly talking about "tube rolling" or "swapping tubes". A question I have for you and the others concerning this: How long (in general) does it normally take for the caps/etc. to completely drain their power "charge" after turning the amplifier off? I've always turned the amp off, unplugged it, and made sure to wait 30 seconds or so (actually several minutes or longer with power tubes to allow their heat to dissipate) before starting to remove tubes for replacement.

Anyway - appreciate your post and welcome to TB...we tube junkies are always looking for advice and help with tube preamps and amplifiers!

Jay
 
#22
vicenzajay said:
Paul,

Great point - and something that I think many of us discount when glibly talking about "tube rolling" or "swapping tubes". A question I have for you and the others concerning this: How long (in general) does it normally take for the caps/etc. to completely drain their power "charge" after turning the amplifier off? I've always turned the amp off, unplugged it, and made sure to wait 30 seconds or so (actually several minutes or longer with power tubes to allow their heat to dissipate) before starting to remove tubes for replacement.

Anyway - appreciate your post and welcome to TB...we tube junkies are always looking for advice and help with tube preamps and amplifiers!

Jay
Click to expand...

Thanks Jay - appreciate the kind words. The last thing I wanted to do was start a war, only to help as best I could. Yes I am new to the site and my last exposure to something like this was back in the BBS days. I guess I jumped in with both feet trying to answer questions I felt I had an angle on. No harm or disrespect was meant.

To try and answer your question the length of time for caps to discharge varies from amp to amp. Most tube amps have as their main filter a pair of caps in series each with a bleeder resistor to equalize the voltage across them. Fender with 2x70mfd caps with 220K resistors for example. These amps will bleed off their charge in a few minutes. However some amps don't have the resistors (not such a good idea) and, depending on the condition of the caps, can hold their charge much much longer. When just swapping tubes the charge is not that important, I just turn off the standby. Just don't break the glass of the tube. :) It's only when you are going inside the amp that a full discharge is required. The easy way to speed this up is to have a 10K 5-10W resistor cabled to a couple of insulated clips and use this between ground and each of the filter caps in turn starting at the power supply end. This will discharge the caps quite quickly. Mine is attached to the wall over my bench with a hook beneath it that I coil the cable over when not in use. I always pre-discharge the amp by turning off the power, with the standby on, while the tubes are hot thus letting the tubes themselves drain the caps.

Hope this answers your question.

Paul
 
#23
BassmanPaul said:
Thanks Jay - appreciate the kind words. The last thing I wanted to do was start a war, only to help as best I could. Yes I am new to the site and my last exposure to something like this was back in the BBS days. I guess I jumped in with both feet trying to answer questions I felt I had an angle on. No harm or disrespect was meant.

To try and answer your question the length of time for caps to discharge varies from amp to amp. Most tube amps have as their main filter a pair of caps in series each with a bleeder resistor to equalize the voltage across them. Fender with 2x70mfd caps with 220K resistors for example. These amps will bleed off their charge in a few minutes. However some amps don't have the resistors (not such a good idea) and, depending on the condition of the caps, can hold their charge much much longer. When just swapping tubes the charge is not that important, I just turn off the standby. Just don't break the glass of the tube. :) It's only when you are going inside the amp that a full discharge is required. The easy way to speed this up is to have a 10K 5-10W resistor cabled to a couple of insulated clips and use this between ground and each of the filter caps in turn starting at the power supply end. This will discharge the caps quite quickly. Mine is attached to the wall over my bench with a hook beneath it that I coil the cable over when not in use. I always pre-discharge the amp by turning off the power, with the standby on, while the tubes are hot thus letting the tubes themselves drain the caps.

Hope this answers your question.

Paul
Click to expand...

Great info - I have been using the approach of turning off the power with the standby on if I'm planning on taking covers off to get at tubes...although I wasn't very knowleadgeable about the theory behind it....thanks for taking the time to share it. Although I must say, I have no intention of actually mucking around with the innards of a tube amp...swapping tubes is enough fun for me!

Take care,
Jay
 
#24
There seems to be quite a few experienced players here:

What's the deal with the Phase Splitter? I notice that no one ever swaps it out, and I'm just curious as to why. I talked to a guy at a new shop in town about ordering some JJ tubes for my YBA (a 12ax7 and a 12at7), and the thought just crossed my mind that no one ever changes this. Why?
 
#25
vicenzajay said:
The YBA-200 is auto-biasing...which, while it means that the bias settings might not be optimal for different tube types, you can just pull and plug. Just turn the power off, unplug, and wait a bit before pulling and plugging and you'll be fine...I've messed with all the tubes on mine countless times...it's easy to work with.

I recommend a JAN Philips or NOS 12AT7 or 5751...they've worked wonders in my amp.

There is, by the way, NO option or set of pots to manually do anything with the bias on the YBA-200.

Jay
Click to expand...

Phillips 12ax7's/7025's great tubes if you want punch, they are in your face, but I think Jack might be looking for smooth.

Also there's allot written here about who know's what, and your OK with those KT88's in there, they might just be a little cool, which can translate into clean and more dynamic.

and something about a phase splitter, your ok to experiment with that, but I'd stick with the recomended type or close to it for gain purposes, and don't use a 12dw7 in there. I hear the JJ's are very well balance for phase splitting, and you might want to throw one in there after the tung-sol 5751, if you use the tung-sol (make sure it's an original tung-sol), to help clean it up or in V2 maybe, like I said warm and it's very smooth, very tubey, and may be considered muddy. Maybe try the 5751 in V2 if it's too much in V1 so there you have it MHO!:D Experiment!!!
 
#27
SnakeAnthony said:
There seems to be quite a few experienced players here:

What's the deal with the Phase Splitter? I notice that no one ever swaps it out, and I'm just curious as to why. I talked to a guy at a new shop in town about ordering some JJ tubes for my YBA (a 12ax7 and a 12at7), and the thought just crossed my mind that no one ever changes this. Why?
Click to expand...

I hope I am answering your question with this message. The phase splitter (PS) takes the input signal from the front end of the amp and splits it in to two identical (in theory, nothing's ever perfect) signals 180 degrees apart. These signals are fed into the top and bottom sets of output tubes thus when the top tube is amplifying the positive going part of the signal the bottom tube is doing the same to the negative. So you get push/pull.

Some amp designs actually run the PS at a fair plate current and would use say a 12AU7 in this position. Putting a 12AX7 here for this design would lead to premature failure because of the differing plate ratings. Other designs apply the neagative bias to the PS itself and not the output stage directly. Other designs apply the bias to a driver tube placed between the PS and the output tubes. Changing tubes in either of the latter designs could and probably would completely destabilize the output stage possibly leading to expensive repairs. In lower class (not meaning quality but output power) amps (50/100W Fender Marshall etc) you could change out the PS tube quite readily. Most Fender amps use a 12AT7 as the PS but others use exactly the same circuit values and run a 12AX7. If you stay within the same type of tube (12AT7 and it's military and industrial equivalents) you'll be fine.

Paul
 
#30
...wouldn't it be hard to be electrocuted if the amp is UNPLUGGED! I'm sure there are no capacitors in the amp big enough to kill a person. If you work on your amp while it is still plugged in...I think you need help nobody on TalkBass could provide!
 
#31
Greyvagabond said:
...wouldn't it be hard to be electrocuted if the amp is UNPLUGGED! I'm sure there are no capacitors in the amp big enough to kill a person. If you work on your amp while it is still plugged in...I think you need help nobody on TalkBass could provide!
Click to expand...
You'd be quite wrong there. There is more than enough storage capacity in a tube amp to kill. Tech use discharging ccts to make sure it does actually discharge and measure voltages before they work on it. On an unplugged amp, charge can remain for a long time.
 
#32
Greyvagabond said:
...wouldn't it be hard to be electrocuted if the amp is UNPLUGGED! I'm sure there are no capacitors in the amp big enough to kill a person. If you work on your amp while it is still plugged in...I think you need help nobody on TalkBass could provide!
Click to expand...

How do you find a faulty circuit if the amp is NOT plugged in???? The only way to isolate a fault is to work on the live chassis.

As A9X has stated there is indeed more than enough voltage left in an amp that is unplugged from the power to kill you fairly quickly. There is also enough power in SS amps to give you a good burn if you bridge the supply caps. Some of the higher powered SS amps are running supplies of more than + and - 120V. This is the same voltage range that your stove works in and is enough to kill you too!!!!

If you do not know what you are doing and have no experience of high voltage circuitry ou have no business opening up an amplifier. Think about it - is your life not worth a few hundred bucks???.

I encourage any player who is using an amplifier to learn about electronics. It's the same thing in my book as learning how to set up your bass. Take a night school course, look for people who work on amps and ask questions, think about building some small electronic projects. There are kits for building small fairly low voltage tube amps available. Not much use to a bass player but a guitar player could use them for recording and such. They will give experience in tube electronics.

Paul
 
#35
Spector_Ray said:
The second generation YBA200's aren't auto-biasing so the best thing to do is take it to a qualified tech.
Click to expand...

Besides that feature and the new faceplate, what else, if anything distinguishes the YBA200-2 from the former YBA200?

Oh and welcome to TB BassManPaul! Glad to have you here and I thought you handled the situation wonderfully!

-FF


P.S. I heard it through that grapevine that Ol' Funkster bought hisself one! :smug:
 
#36
Wow! Ok, I read your posts, and you clearly know what you are talking about. Good to know; the most I've ever done to my tube amp is swapping the preamp tubes, so now I know better than to go mucking about with the circuitry! I was thinking of switching the power tubes in my YBA200-2 to KT88s, but I was going to bring it in to a tech, so that he could re-bias it himself. I've heard YBA200 run cold with KT88s. Can they be rebiased to run at full capacity, or would the transformer not be able to take it!

PS Thanks for the advice!
 
#37
I have read about all the tube swaps that can be done with this amp and a lot of complaints about the amp having no mids and too much high end. I found this to be true until I changed cabs. Through my Aguilar 410 it is indeed to bright and clanky sounding(even with the tweeter all the way off) but through my Begantino NV425 tight punchy mids with just enough low end woof. Using the Berg I wouldn't do any mods to change the tone, when the tubes start to go I'll worry about that. Tube swaps would be cheaper but you might want to play it through a nonported cab with no tweeter.
 
#38
BassmanPaul said:
I hope I am answering your question with this message. The phase splitter (PS) takes the input signal from the front end of the amp and splits it in to two identical (in theory, nothing's ever perfect) signals 180 degrees apart. These signals are fed into the top and bottom sets of output tubes thus when the top tube is amplifying the positive going part of the signal the bottom tube is doing the same to the negative. So you get push/pull.

Some amp designs actually run the PS at a fair plate current and would use say a 12AU7 in this position. Putting a 12AX7 here for this design would lead to premature failure because of the differing plate ratings. Other designs apply the neagative bias to the PS itself and not the output stage directly. Other designs apply the bias to a driver tube placed between the PS and the output tubes. Changing tubes in either of the latter designs could and probably would completely destabilize the output stage possibly leading to expensive repairs. In lower class (not meaning quality but output power) amps (50/100W Fender Marshall etc) you could change out the PS tube quite readily. Most Fender amps use a 12AT7 as the PS but others use exactly the same circuit values and run a 12AX7. If you stay within the same type of tube (12AT7 and it's military and industrial equivalents) you'll be fine.

Paul
Click to expand...


Ok, I get it now. Thanks man. I completley forgot that I had asked this question too.

So what type of tube is stock in the YBA for the PS position? Sorry if this has been stated already...
 
#40
Frankie Fender said:
Besides that feature and the new faceplate, what else, if anything distinguishes the YBA200-2 from the former YBA200?

Oh and welcome to TB BassManPaul! Glad to have you here and I thought you handled the situation wonderfully!

-FF


P.S. I heard it through that grapevine that Ol' Funkster bought hisself one! :smug:
Click to expand...

Thanks for the greeting and the kind words of support. I must admit I was feeling somewhat beleaguered for a while there!

Paul
 

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