Tony's lowdown on tube pp amp DIY....

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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Mon Dec 24, 2012 1:52 pm

2 pairs of tubes.....
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Re: Tony's lowdown on tube pp amp DIY....

Postby kabubi » Mon Dec 24, 2012 5:48 pm

tony wrote:2 pairs of tubes.....


:o :o :o :o :o :o :o

that is something! looking forward to this make of yours, O Sultan of Sakhalin :) :) :)
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Mon Dec 24, 2012 6:07 pm

a qaudie of 6336 can get you about the same power output... 8)
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Re: Tony's lowdown on tube pp amp DIY....

Postby kabubi » Mon Dec 24, 2012 6:14 pm

Sir Tony,

what is a better tube for audio application:

one that is high current or low voltage or one that is low current but high voltage?
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Mon Dec 24, 2012 7:27 pm

kabubi wrote:Sir Tony,

what is a better tube for audio application:

one that is high current or low voltage or one that is low current but high voltage?


depends on what you aim for....for me it is not the tubes per se, but what you do with the tube that matters.... 8)

high voltage low current tubes implies high plate resistances necessitating high impedance OPTs that required elaborate OPT designs because of the higher required inductance for decent low frequency response...

low voltage high current tubes OTOH have lowish plate resistance like for the 6C33 that has typically 150 ohm plate resistance thus making designs of the OPT very easy and less critical....the challenge with low voltage tubes is in the drive circuitry.....

but one thing is sure, working with high voltages is scary, i still bear scars on my hands from injuries suffered a long time ago...... :worried:
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Re: Tony's lowdown on tube pp amp DIY....

Postby georgepogi69 » Tue Dec 25, 2012 6:01 pm

just to back up what boss tony's lowdown on DIY tube amp, i have attached a link on the stores that sell tubes on our side of the planet, only well-audio has the prices on their site, http://www.wellaudiolab.com/poweramp-nos.html just the same, ito naman yung ibang tubes supplier but no prices, http://www.larryhifi.com/tubes.html , http://www.ahfartaudio.com/about/who.html ....

hope this helps.... :)

tony wrote:After the HiFi show at the Dusit Hotel, i have received numerous inquiries about push pull tube amps...when asked
about how much they were willing to spend, all of them came up with low figures giving me the impression that most
folks think that DIY was a cheap way to acquire a tube power amp...could they be correct? let us find out...we will
not consider boutique parts in this discussion, only those that are available from usual sources....

this is my pp EL34 amp...

Image

2. next comes the power tubes....

2.1 JJ seems to be a reliable new production tubes and is available here:i found a local source, their service is
top notch, http://www.epektos.com/catalog/90270c5d ... 4af81.aspx

2.1.1 quad prices for new tubes are as follows, EL34----P3,000; 6L6GC----P3,300, note that you will have to add 150
for shipping......

Image
Image

2.2 Balik-bayan Handicrafts is also a good place to get tubes, large discounts from time to time...

2.3 I also buy from the states NOS TV tubes, these are U$1 each, i find TV tubes as good sounding as the other so
called audio tubes, unfortunately local folks are slow to recognize their virtues nor use them....

2.4. Russian tubes are a revelation to me, they are awesome....and very cheap....

2.4 Gerry Sta Maria, 400-2762 is the other one of my unsung heroes, he can smell tubes a few kilometers away ;D

2.5 the small tubes can set you back another P1000 for a pair of 6CG7, and the 6J9's another P500 for a pair

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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Wed Dec 26, 2012 10:07 am

^that was good info George, i have not been to Singapore since 2000, i have a brother who is a PR,and stays at Chua Chu Kang with his family :) ....

i buy my $1 tubes here....http://www.vacuumtubes.net/
Last edited by tony on Wed Dec 26, 2012 10:09 am, edited 1 time in total.
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Wed Dec 26, 2012 10:07 am

The power transformer used on pushpull amps is one of if not the single biggest expense item in any buld. It is also one of the easily over-looked item in any build, yet i believe that the power traffo can also make a big contribution to the success of any amplifier build......

the Radiotron Designers' Handbook, chapter 5, page 235 gives the core power handling capacity as:

VA = (A*5.58)^squared, where A equals area under the core in square inches, 5.58 is a constant, VA is the volt-ampere capacity..

VA is determined by computing for filament power,(current x voltage), the plate wattage inputs for a given watt output....the sum of all of these are the power that the secondary of the power transformer needs to deliver...

if you want to know if your amps are designed properly you can use the above formula to find out...

Knowing the secondary power, we can then compute for the primary volt-amperes:

VAp=Ps/0.7, where Ps is the secondary power computed and 0.7 is to compensate for primary losses, VAp is the primary volt-ampere capacity....

Here, a DIY amp can splurge and give as many allowance as one wishes, after all you are only making one unit, compared to commercial production power traffos, profits will be eaten up easily if the designer gives too much of an allowance....

and this is where DIY can beat commercially mass produced amps.....

the other advantage of having such a big allowance in power transformer capacity is in the area of temperature rise, using a bigger core, and so enabling the use of bigger sized copper wires makes for a cooler running amp.

link to winding your own power transformers....http://geek.scorpiorising.ca/lcms/index ... ansformers http://www.diyaudio.com/forums/power-su ... rmers.html http://www.k5rmg.org/transformers/6.html http://wb0nni.dakotamade.com/xformrs.html

video link....
http://www.youtube.com/watch?v=s6NyTprQCBI

the Radiotron Engineer's Handbooks 3'rd and 4th editions can be downloaded here, along with a lot of other tube books for free....http://www.tubebooks.org/technical_books_online.htm
next lowdown will be about OPT's or output transformers....
Last edited by tony on Sun Dec 30, 2012 8:58 am, edited 2 times in total.
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Thu Dec 27, 2012 12:09 pm

lowdown on OPT's....

Since the plate resistance of any tube is rather high, it can not directly drive speakers, of course there is the OTL configuration, but that is not considered here....

There are many who are of the belief that without the OPT's there can be no tube amp, admittedly i am one of them...

Unlike the power traffo which need to operate at just the line frequency, say 50 or 60 Hz,the OPT's live a more difficult life, it has to operate at a band of frequencies from say 20 Hz to 20 kHz...

Design of the OPT's are therefore much more complicated than the design of the power traffo....some regard it as more of an art than science, so much so that there are those OPT winders who are adamant to divulge their trade secrets.....but diy'ers can not be slowed down because of that, reverse engineering is key...

We should indeed be thankful that we live in a time when all information are just mouse-clicks away...

Needless to say, the OPT has a big big role to play in any tube amp....the two main hurdles for an OPT is core saturation, and leakage inductance/shunt capacitance...

core saturation has a lot to do with core size, the smaller the core, the more easily it saturates, power levels also has to do with this.....M6/Z11 is mandatory for EI type, there are also C cores that can deliver more power than an EI of the same dimensions....

leakage inductance/shunt capacitance is about coil winding geometry and inter-layer insulation, to day Teflon and other plastics are used instead of the traditional paper insulation, today, paper is only used as an outer wrapping material....

like in the power traffo, the core area determines to power handling capacity of the OPT, to estimate power handling, the formula given by RDH4 can be used, divide by a factor of 3 to get the 20 Hz power handling capacity...

below is the Dynaco OPT tables of days gone by....

Image
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Tue Feb 05, 2013 12:06 pm

What's up with WATTS?

i stopped counting watts a long time ago.... as a determinant of quality power rating hardly matters imho......

long before the FTC trade regulations of 1972....tube output power ratings were determined on the basis of operating points of tubes used...tube manufacturers paid some people to find operating points, meaning load conditions, plate and bias voltages that gives a certain power with a respectable distortion, usually less than 5%..

to me as long as you are able to drive your speakers to a level that suits your taste in your own listening environment, then is all that is important to you...

but why power ratings?

because it gives you an idea of how heavy your amp ought to be....and naturally, the heavier your amp is, the more it costs....a higher powered amp will give more headrooom and can drive many types of speakers.....but if you already have sensitive speakers to begin with, then high powered amps are not that important....
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Mon Mar 04, 2013 8:12 pm

these are a pair of Theta monoblocks using the 6550 inputr tubes driven by a 6AN8 input tube...

Image

to give Diy'ers an idea, the OPT's of this amp is bigger than the power traffo.....the amp used 1N4007 ss rects and massive filtering...this is how i like to build my amps, i like the massive filtering since it can give a lot of current reserves on demand...the power traffo is a 1 1/2 x 2 inches stack, the opt otoh is stacked about 2 1/4 inch thick.....the reason for this is that the power traffo had only to rectify the 60hz line, the output traffo has to work a wider range of frequencies..

Image

the amps are american designed.....and i believe that this is how a tube amp should be built in terms of irons....any smaller will not do justice to the 6550 tube...
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Re: Tony's lowdown on tube pp amp DIY....

Postby 0760.lorelei » Wed Mar 13, 2013 2:27 pm

sir tony pm pls need your recom for a traffos na pwede gumawa...im planning to build Cavali Jones Headphone amp...nakalagay na info lang sir is 190-0-190 65ma, 6.3v 2A, Choke 5H 50ma can you recommend 1 who can do it poh....same as you na good quality ang gawa poh.... :) thanks.
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Thu Mar 14, 2013 5:42 am

you can pm edrel sison here.....
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Re: Tony's lowdown on tube pp amp DIY....

Postby alexg » Tue Mar 19, 2013 3:37 pm

tony wrote:
depends on what you aim for....for me it is not the tubes per se, but what you do with the tube that matters.... 8)

high voltage low current tubes implies high plate resistances necessitating high impedance OPTs that required elaborate OPT designs because of the higher required inductance for decent low frequency response...

low voltage high current tubes OTOH have lowish plate resistance like for the 6C33 that has typically 150 ohm plate resistance thus making designs of the OPT very easy and less critical....the challenge with low voltage tubes is in the drive circuitry.....

but one thing is sure, working with high voltages is scary, i still bear scars on my hands from injuries suffered a long time ago...... :worried:


I will not DIY any amp with B+ more than 500VDC. First, it is scary, one mistake and you are toast (literally) and second, parts, like capacitors, resistors are more expensive on voltages higher than 500VDC. :(
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Tue Mar 19, 2013 6:19 pm

alexg wrote:
tony wrote:
depends on what you aim for....for me it is not the tubes per se, but what you do with the tube that matters.... 8)

high voltage low current tubes implies high plate resistances necessitating high impedance OPTs that required elaborate OPT designs because of the higher required inductance for decent low frequency response...

low voltage high current tubes OTOH have lowish plate resistance like for the 6C33 that has typically 150 ohm plate resistance thus making designs of the OPT very easy and less critical....the challenge with low voltage tubes is in the drive circuitry.....

but one thing is sure, working with high voltages is scary, i still bear scars on my hands from injuries suffered a long time ago...... :worried:


I will not DIY any amp with B+ more than 500VDC. First, it is scary, one mistake and you are toast (literally) and second, parts, like capacitors, resistors are more expensive on voltages higher than 500VDC. :(


hey Alexg, you are right....i am working on an 813 set with B+ of 900volts, now making the irons and this early i am scared....being scared is good, keeps you on your toes all the time, as i have high voltage experience having worked around equipment running 110kv's, i think i will be okay..... ;)
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Wed Mar 20, 2013 7:19 am

another tip, when working on tube amps, make sure to use rubber soled shoes, a clear glass "safety glass" is also good to use.... 8)
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Mon Jul 29, 2013 8:40 pm

Let's talk about power tubes....

KT-120......http://www.jogis-roehrenbude.de/Roehren ... ungSol.pdf
KT-88.......http://www.r-type.org/pdfs/kt88.pdf
6550........http://www.dougstubes.com/6550-tungsol.pdf
6L6GC......http://www.radiostation.ru/tubes/6L6GC-GE.pdf
EL34........http://www.r-type.org/pdfs/el34.pdf

one spec that gets my attention with these tubes is the maximum cathode current ratings...
KT-120, Ik at 250mA, 60 watts anode dissipation
KT88, Ik at 230mA, 46 watts anode dissipation
6550, Ik at 190mA, 42 watts anode dissipation
6L6GC, 30watts anode dissipation
6CA7/EL34, Ik at 150mA, 24 watts anode dissipation

how then do these power tubes compare with other power tubes, like say TV horizontal scanning tubes..
6LW6/6LF6, Ik at 1400mA peak, average Ik at 400mA, anode dissipation 40 watts.... http://frank.pocnet.net/sheets/084/6/6LF6.pdf
6HF5, Ik at 1100mA peak, average Ik at 315mA, anode dissipation 30 watts.... http://frank.pocnet.net/sheets/127/6/6HF5.pdf
6GV5, Ik at 550mA peak, average Ik at 175mA, anode dissipation 17.5 watts... http://frank.pocnet.net/sheets/127/6/6GV5.pdfs

here we see that scanning tubes wins hands down when it comes to power delivery....
something to ponder upon.... 8)
Last edited by tony on Tue Jul 30, 2013 8:11 pm, edited 1 time in total.
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Tue Jul 30, 2013 12:11 pm

just in case you are wondering, the tube's Ik or cathode ratings
is analogous to collector current spec of bipolars....
very important for large signal conditions...
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Re: Tony's lowdown on tube pp amp DIY....

Postby tony » Thu Aug 01, 2013 7:20 am

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Re: Tony's lowdown on tube pp amp DIY....

Postby don » Thu Aug 01, 2013 2:47 pm

Papa Tony, Happy Birthday! :)
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