Author Topic: Newbie and Not-so Noob Thread: Questions (FAQ) on anything Tubes (Read 98355 times)

RU9 · « **Reply #330 on:** Feb 08, 2006 at 11:48 AM »

Quote from: JojoD818 on Feb 08, 2006 at 09:27 AM

With a large, off specification input cap, your tube rectifier is bound to die sooner than is expected.

Best Regards,
JojoD

I believe this is the problem. Will have it fixed.

Thanks for your explanation.

Louie

JojoD818 · « **Reply #331 on:** Feb 08, 2006 at 02:31 PM »

Quote from: RU9 on Feb 08, 2006 at 11:48 AM

I believe this is the problem. Will have it fixed.

Thanks for your explanation.

Louie

No problem Louie, anytime.

Oh and the recommended maximum input cap values can be found in the tube rectifier's datasheet.

Best Regards

JojoD818 · « **Reply #332 on:** Feb 08, 2006 at 02:33 PM »

Quote from: ricky on Feb 08, 2006 at 09:39 AM

Hi mga tube gurus, ask ko lang po sana kasi lately yung ts audio ni misis hindi na ganon kaganda tumunog,medyo garalgal na.I suspect yung tube nya medyo mahina na pero up to now tumutunog pa naman,so ang question ko when will i know when to replace the tube and what tube to replace?

what are the tube compliments? is it pp or set? ss or tube rectified?

odyopayl · « **Reply #333 on:** Feb 08, 2006 at 06:21 PM »

Quote from: ricky on Feb 08, 2006 at 09:39 AM

Hi mga tube gurus, ask ko lang po sana kasi lately yung ts audio ni misis hindi na ganon kaganda tumunog,medyo garalgal na.I suspect yung tube nya medyo mahina na pero up to now tumutunog pa naman,so ang question ko when will i know when to replace the tube and what tube to replace?

I'm not tube Guru but possibly it might be Capacitors or something to do with the PSU, is it Tube rectified? How old is your Amp? My suggestion bring it to JojoD para ma-resolve agad yan, upgrade mo na rin

ricky · « **Reply #334 on:** Feb 08, 2006 at 08:30 PM »

Quote from: JojoD818 on Feb 08, 2006 at 02:33 PM

what are the tube compliments? is it pp or set? ss or tube rectified?

Sir jojoD818 its Ts audio 34.1 single ended pentode and tube rectified po ito, with 2-el34, 2-12ax7 and 1- 5ar4.

Sir odyopayl no plans to upgrade po,my wife and i are still happy with the sound nitong ts and its more than a year na and wala pa ako napalitan na tube ni isa

around 3hrs use everyday since we bought this.

JojoD818 · « **Reply #335 on:** Feb 08, 2006 at 08:46 PM »

Quote from: odyopayl on Feb 08, 2006 at 06:21 PM

I'm not tube Guru but possibly it might be Capacitors or something to do with the PSU, is it Tube rectified? How old is your Amp? My suggestion bring it to JojoD para ma-resolve agad yan, upgrade mo na rin

Hindi din ako tube guru ha, student pwede pa.

Quote from: ricky on Feb 08, 2006 at 08:30 PM

Sir jojoD818 its Ts audio 34.1 single ended pentode and tube rectified po ito, with 2-el34, 2-12ax7 and 1- 5ar4.

Sir odyopayl no plans to upgrade po,my wife and i are still happy with the sound nitong ts and its more than a year na and wala pa ako napalitan na tube ni isa around 3hrs use everyday since we bought this.

Hi ricky,

I hope I get it right, at low listening levels it's not distorted, but at higher volumes it starts to distorts. If this is the case then the best candidates are the 5AR4 and of course the power tubes since SEP like most SET operates in pure class A so the tubes are always conducting. If it were mine I'll borrow a known good 5AR4 first, if the distortion is not removed then maybe it's time to get a fresh pair of EL34 tubes. If the distortion is evident from low to high volumes try replacing the 5AR4, the rectifier may not be supplying enough voltage to your amp. If this doesn't fix it then we will go to the next step.

Provided that the 12AX7s are of good quality, they almost always last a lifetime. Baka may apo ka na buo pa yan.

cheers

ATJr. · « **Reply #336 on:** Feb 09, 2006 at 08:42 AM »

Quote from: ricky on Feb 08, 2006 at 09:39 AM

Hi mga tube gurus, ask ko lang po sana kasi lately yung ts audio ni misis hindi na ganon kaganda tumunog,medyo garalgal na.I suspect yung tube nya medyo mahina na pero up to now tumutunog pa naman,so ang question ko when will i know when to replace the tube and what tube to replace?

two things could have happened here:

1. nasanay ka na sa tunog, sinawaan ka na. garalgal is a symptom that your amp is clipping, back down on the volume.

2. tubes, specially output tubes could have worn-out, you can confirm that by simply directly replacing it with a new one and see if it solves the problem. it is good idea to have replacement tubes on hand, you can tube roll it to find out.

ricky · « **Reply #337 on:** Feb 09, 2006 at 09:34 AM »

Sir jojod thank you very much for that very detailed instruction,yes it becomes distorted at high volume levels say at midway.Ill try to look for a rectifier tube na 5ar4 and pwede din po ba yung coke bottle na 5u4g?

sir 2ny thanks din po,yes it was my plan before to buy different brands of 5ar4 and el34 for tube rolling purposes but sadly i wasnt able to attend to it,naubos po pera ko sa dvd collecting

JojoD818 · « **Reply #338 on:** Feb 09, 2006 at 11:12 AM »

Quote from: ricky on Feb 09, 2006 at 09:34 AM

Sir jojod thank you very much for that very detailed instruction,yes it becomes distorted at high volume levels say at midway.Ill try to look for a rectifier tube na 5ar4 and pwede din po ba yung coke bottle na 5u4g?

5U4G? For testing purposes yes, but your tests maybe inaccurate since you will yield a lower B+ when you use a 5U4G in place of the 5AR4.

If in the past it worked flawlessly even at past mid volume settings, then I'm pretty sure your problems can be solved by using tube replacements.

regards

MAtZTER · « **Reply #339 on:** Feb 10, 2006 at 11:05 AM »

Whats the best option to use for a SS amp for a tube/SS amp setup? My current amp is HK630 for receiver and a rotel power amp.

1.) Tube CDP?
2.) Tube pre amp?
3.) Tube buffer?

TIA guys

s2kov · « **Reply #340 on:** Feb 10, 2006 at 11:09 AM »

If you already have a dedicated cdp, just add tube buffer! Kung wala pa, tube cdp ka na!

ricky · « **Reply #341 on:** Feb 10, 2006 at 11:15 AM »

ako din sir s2kov tube cdp din suggestion ko sa kanya kasi super SS na set-up nya right now eh para magkaroon naman ng lambing yung audio nya

s2kov · « **Reply #342 on:** Feb 10, 2006 at 11:21 AM »

naku! dyan nagsisimula yan!

anyway, kaya namn ni matt eh!

ricky · « **Reply #343 on:** Feb 10, 2006 at 11:42 AM »

sir s2kov ano po ba yung tube buffer? what does it do and how much would it cost? mas ok ba ito compared to outboard DAC?

s2kov · « **Reply #344 on:** Feb 10, 2006 at 02:15 PM »

Tube buffer has good drive capability. Usually, no gain at all that gives low output impedance to match with your amp.

If you have a CDP that has good quality DAC built on it, tube buffer is a good candidate to use instead of using an active preamp!

markmlists · « **Reply #345 on:** Feb 16, 2006 at 10:16 AM »

Just a couple of questions for the gurus and those with experience...

1. What transformers do you use in when you make your prototypes? Do you have one for each tube application or do you have a multipurpose transformer with 'multiple taps' (is there such a thing?) in your test bench?

2. What sort of internal modifications and parts are needed if:

a. I wish to change the driver tubes in my integrated amp from 12ax7 to 6sn7? 6sl7? Do I need a new transformer or is there a workaround in correcting the necessary voltages/current etc?

b. earphone out

c. passive/active preamp section?

3. Related to question #2, would the unit need lesser modifications if I plan to use 12sn7 instead?

4. On Chokes:
What do I look for when buying a used choke if I plan to use it on a preamp project for a 12ax7 family? for the 6sn7 variant? Is there a choke rating similar to transformer rating (xvolts-0-xvolts)?

Thanks.

JojoD818 · « **Reply #346 on:** Feb 16, 2006 at 12:11 PM »

you may not need a new transformer for a 12ax7 to 6sl7 switch. normally the psu has some sort of dropping resistor which you can adjust to reach your desired supply for the 6sl7. if the heaters of the 12ax7 were wired for 6.3V operation then there wouldn't be much of a problem but if it is at 12.6V heater setup then maybe a 12sn7 would do but their gain and mu are from opposite sides of the world.

yes, it is useful to have a multi-tapped tranny for bench use.

changing from 12AX7 to whatever tube you like requires some computation so you can be sure that your new tube driver can deliver the required voltage swing etc. to your next stage.

s2kov · « **Reply #347 on:** Feb 16, 2006 at 02:49 PM »

You can go to Podmoon in legarda for you power transformer needs!

arnoldc · « **Reply #348 on:** Feb 16, 2006 at 04:39 PM »

Quote from: markmlists on Feb 16, 2006 at 10:16 AM

Just a couple of questions for the gurus and those with experience...

1. What transformers do you use in when you make your prototypes? Do you have one for each tube application or do you have a multipurpose transformer with 'multiple taps' (is there such a thing?) in your test bench?

2. What sort of internal modifications and parts are needed if:

a. I wish to change the driver tubes in my integrated amp from 12ax7 to 6sn7? 6sl7? Do I need a new transformer or is there a workaround in correcting the necessary voltages/current etc?

b. earphone out

c. passive/active preamp section?

3. Related to question #2, would the unit need lesser modifications if I plan to use 12sn7 instead?

4. On Chokes:
What do I look for when buying a used choke if I plan to use it on a preamp project for a 12ax7 family? for the 6sn7 variant? Is there a choke rating similar to transformer rating (xvolts-0-xvolts)?

Thanks.

1. What type of transformer? Power? Output? My amp prototyping chassis use Hammond 125ESE (from www.angela.com) output transformers due to the multiple primary/secondary connections I can use. The power transformer is sort of a "universal" type with several taps.

2a. Many factors have to be considered which will include the physical (octal vs. 9-pin), filament voltage/current, biasing, gain, drive capability, plate resistance, voltage and current issues. For example, the 12AX7 has a gain of 100 while the 6SL7 is 70.

2b. Use an impedance matching transformer for your headphone via the speaker output.

2c. in a passive mode, you feed the driver tube directly from a volume potentiometer. Depending on the circuit, you will have input impendance issues to consider.

3. 12SN7 is simply a 12.6V version of 6SN7

4. You need to determine the inductance, current capacity and DC resistance for you circuit. The rating is given as henry (inductance), mA (current), and DCR (impedance ). Example is 10H, 100mA, 100ohm DCR.

markmlists · « **Reply #349 on:** Feb 16, 2006 at 07:59 PM »

Thank you sirs for your input. Others are welcome to share theirs as well.

Abad Santos 7 · « **Reply #350 on:** Feb 22, 2006 at 11:22 AM »

Team,

Patanong lang po. I dont know if this has been asked already.

Considering the layout and configuration of KT66 and EL34, is almost the same except for Pin 1,
Can I substitute KT66 to EL 34 parang KT88 to 6550( I dont konw if I understand it also correct for the latter).

Appreciate your advise.

Cheers.

arnoldc · « **Reply #351 on:** Feb 23, 2006 at 08:22 AM »

How familiar are you with the design of the amp? For starters, the EL34 max plate voltage is 800V whereas the KT66 is only 500V, the screen voltage of the EL34 is 500 max, while the KT66 is 400. depending on the design, you cannot just plug in a KT66 on an EL34-based amp. Dagdagan ko pa- they also have different output impedance.

Abad Santos 7 · « **Reply #352 on:** Feb 23, 2006 at 11:15 AM »

Thanks po Sir Arnoldc. I thought it is just a simple plug and play. Anyway thanks very much and you were very helpful.

Cheers.

devo · « **Reply #353 on:** Mar 20, 2006 at 01:02 PM »

just a couple of questions............

1. what's the difference in terms of sonics/musicality of a winged-c EL34 from a non-winged C?

2. same question as above, between a 6550 and an EL34?

TIA

Larry_Boy · « **Reply #354 on:** Apr 03, 2006 at 01:21 PM »

have the following questions as well:

1) what set of tubes should i change first which will affect/improve the sound of the amp the most? (i.e. pre, output, etc.)

2) aside from mullard, any recommended brand for a 12ax7 tube? for a 12au7? for el34?

i just want to know your preferences so that i will not start from scratch.

maraming salamat!!!

eXg · « **Reply #355 on:** Apr 10, 2006 at 08:50 PM »

Quote from: Larry_Boy on Apr 03, 2006 at 01:21 PM

have the following questions as well:

1) what set of tubes should i change first which will affect/improve the sound of the amp the most? (i.e. pre, output, etc.)

A: I follow the principle that earliest stage makes the biggest impact: Input, Driver, then Output.

2) aside from mullard, any recommended brand for a 12ax7 tube? for a 12au7? for el34?

A: Be blindfolded, ask a friend to try several brands to try in your amp. Will take a lot of time but will definitely give you qualified results more than the bias of brandnames. For me, that is a preferrable approach. At any rate, search the web and you'll find people going crazy about some brands of these tubes. These may be true in their experience.

ATJr. · « **Reply #356 on:** Apr 11, 2006 at 10:44 AM »

there will be differences, that is for sure, the question is, should it matter to you? is it worth the expense?

Dracula · « **Reply #357 on:** Apr 12, 2006 at 01:53 PM »

I want to replace the stock tubes on my amp how do I adjust the bias?

What tools do I need? Is it easy enough to do? (I have zero electronic know how!

) Not planning on experimenting with different tubes just want to be able to replace a busted tube....or would it be better to just bring it to hyperaudio or JojoD818?

Sir Jojo do you do house calls?

Thanks

arnoldc · « **Reply #358 on:** Apr 12, 2006 at 03:04 PM »

Dracula, I thought you got the PrimaLuna with the auto-bias board? Hindi kailangan ng manual bias for that.

arnoldc · « **Reply #359 on:** Apr 12, 2006 at 03:11 PM »

Quote from: devo on Mar 20, 2006 at 01:02 PM

just a couple of questions............

1. what's the difference in terms of sonics/musicality of a winged-c EL34 from a non-winged C?

2. same question as above, between a 6550 and an EL34?

TIA

Depends on the design of the amp. Hard to generalize. The type of the output transformer used, the "subjective voicing" of the driver stage, the type of splitter (if push pull), the feedback, the class of operation (A, AB1, AB2, B)

Take this with a drum of salt- EL34 may have the edge/advantage on the mids and highs over the 6550. The 6550 will be better in bass, but will be more clinical or analytical. Again, depends on the design!