Author Topic: Newbie and Not-so Noob Thread: Questions (FAQ) on anything Tubes (Read 98653 times)

ATJr. · « **Reply #240 on:** Dec 09, 2005 at 03:21 PM »

yan ba yung copper band around the traffo? kung sandwhiched sya ng shell, magagaround na rin yan. better that it is connected to ground.

JojoD818 · « **Reply #241 on:** Dec 09, 2005 at 09:10 PM »

yup Tony, tama ka it's the one around the EI - for sure grounded ito

. but there is another type of flux band around the core before insertion of the EI, should I bother or just use the customary way of installing a flux band?

since you have a lot of experience and make your own trannies, some advice would be very valuable indeed.

thanks

ATJr. · « **Reply #242 on:** Dec 10, 2005 at 05:58 AM »

you have two choices, one is to use a single layer of magnet wire with one end connected to a ground drain, or you can use a copper, or aluminum foils. btw, i saw copper foils at sulimco. the ends of these foils should not touch, otherwise you have a shorted turn.

these are installed between the primary and secondary windings.

i remember when i wound my first traffo for a leach amp, it used a 1 3/4 in core stacked to 3.5 inch, i used an aluminum duct tape!

JojoD818 · « **Reply #243 on:** Dec 11, 2005 at 08:30 AM »

that's what I'm talking about! nice work!

thanks!

btw, what happened to the tranny with alum duct tape? shorted?

ATJr. · « **Reply #244 on:** Dec 11, 2005 at 09:47 AM »

Quote

btw, what happened to the tranny with alum duct tape? shorted?

of course not! i made it in 1980 for my first super leach amp using japanese output transistors at a rail of +/-63volts.

but my first transformer build attempt when i was about 14, was in smoke the moment i turned on the power, but i have come a long way eversince!

ATJr. · « **Reply #245 on:** Dec 11, 2005 at 12:12 PM »

this is a sneak preview of my upcoming 60watt 6HF5 PP screen grid drive amp. all transformers diy'ed by me! this amp is for my son's elctric guitar

will go to aranque for the aluminum cahssis.

JojoD818 · « **Reply #246 on:** Dec 11, 2005 at 12:25 PM »

Quote from: 2ny on Dec 11, 2005 at 09:47 AM

of course not! i made it in 1980 for my first super leach amp using japanese output transistors at a rail of +/-63volts.

but my first transformer build attempt when i was about 14, was in smoke the moment i turned on the power, but i have come a long way eversince!

i bet almost all serious diyers have seen the magic smoke once or twice in their lifetime. i remember my very first psu caps trajectory landed on the ceiling!

but now I intentionally blow up small caps in lieu of blasting caps for firecrackers during the new year.

your son's amp is looking very good, tell us how it sounds. where do you buy those tranny covers? looks a lot like the ST70 opt trannies yes?

ATJr. · « **Reply #247 on:** Dec 11, 2005 at 02:06 PM »

Quote

where do you buy those tranny covers? looks a lot like the ST70 opt trannies yes??

they are all from deeco! the power transformer as well as output traffos are from EI-150, the filter choke is EI-112. since the cores were from scrapples stampings, i just modded the covers to be used in an upright position as opposed to sideways! fyi, the legs for the ei 1.25 can be used for the ei-1.5 in an upright position! try this and you will see what i mean!;D

the output traffo, i asked a local shop to weld the legs to the cover shell since only two holes can be used. the corner holes do not jibe with the cover shells, sinauna kasi yung core na nakuha ko for the output traffo, that is why i had to improvise, the output traffo is a ei-1 1/2 inch core stacked to about 2 1/2 inch. there is no commercial equivalent for this traffo, ot has a primary impedance of 4.2k p2p to 4 8 and 16 ohm taps, i have even wound a separate feedback winding.

s2kov · « **Reply #248 on:** Dec 11, 2005 at 02:44 PM »

master tony,

can't wait to see the finish product of your son's guitar amp!

JojoD818 · « **Reply #249 on:** Dec 11, 2005 at 04:48 PM »

Gets ko na!

You just drilled a hole below for the wires, paano yun isang butas sa side?

OT: Since bass amp yan pwede pala jamming utol ko and your son since electric guitar naman sa utol ko.

ATJr. · « **Reply #250 on:** Dec 11, 2005 at 09:29 PM »

Quote

paano yun isang butas sa side

i jjust leave it as is, me nabibile na cover sa deeco na walang holes.

ATJr. · « **Reply #251 on:** Dec 11, 2005 at 09:32 PM »

Quote from: s2kov on Dec 11, 2005 at 02:44 PM

master tony,

can't wait to see the finish product of your son's guitar amp!

i hope i can finish this before year's end.

levi · « **Reply #252 on:** Dec 11, 2005 at 09:50 PM »

Sorry to disturb but we are getting off topic. Thanks.

JojoD818 · « **Reply #253 on:** Dec 11, 2005 at 10:21 PM »

Quote from: levi on Dec 11, 2005 at 09:50 PM

Sorry to disturb but we are getting off topic. Thanks.

excuse us sir Levi.

back to topic...

eXg · « **Reply #254 on:** Dec 12, 2005 at 08:00 PM »

does virtual center-tapping work for dc supplies as well?

JojoD818 · « **Reply #255 on:** Dec 12, 2005 at 08:28 PM »

Quote from: eXg on Dec 12, 2005 at 08:00 PM

does virtual center-tapping work for dc supplies as well?

yes, use a voltage divider with parallel caps to halve the voltage potential.

odyopayl · « **Reply #256 on:** Dec 13, 2005 at 04:15 PM »

Is it possible to substitute lets say for a 10uf NP Capacitor using 2 pcs. 5uf e-cap connected in reverse polarity? (+- / +-)

ATJr. · « **Reply #257 on:** Dec 13, 2005 at 04:34 PM »

Quote from: odyopayl on Dec 13, 2005 at 04:15 PM

Is it possible to substitute lets say for a 10uf NP Capacitor using 2 pcs. 5uf e-cap connected in reverse polarity? (+- / +-)

a 10uf film cap is not that hard to find, however if you insist you must, you can series connect two 22ufd eletcros to form a 10ufd NP cap. do it in a - + + - way or vice versa. you can even put a 1meg resistor at the juction and bias the resistor to polarise the caps.

saan ba gagamitin?

eXg · « **Reply #258 on:** Dec 13, 2005 at 04:50 PM »

am so amused

with chip regulators and wonder

if there are AC counterparts for it (not the main regulators, course

'

di ba useful din yan, like regulating the heaters in AC

ATJr. · « **Reply #259 on:** Dec 13, 2005 at 05:47 PM »

Quote from: eXg on Dec 13, 2005 at 04:50 PM

am so amused with chip regulators and wonder if there are AC counterparts for it (not the main regulators, course '

di ba useful din yan, like regulating the heaters in AC

yes, you can use smps types, you heaters will be ac but at 200khz, not 60hz!

tube heaters operate on a certein level, 6.3 say, but a few millivolts more or less will not hurt.
i have observed that power transofrmers loaded or not has a very minimal effect on the filament voltage, so in a well designed power transformer, this should not be an issue.

JojoD818 · « **Reply #260 on:** Dec 13, 2005 at 09:40 PM »

besides the heaters draw a fairly constant amount of current as soon as they reach nominal operating temps, wether they are at AC or DC potentials. though mains fluctuations in this situation can be another story, it has been said that heaters have a certain margin of about +/-10%.

eXg · « **Reply #261 on:** Dec 14, 2005 at 08:37 AM »

O eto naman...

what tubes (or their spec) make good candidates for headphone duties? my mind tells me a separate secondary winding for OPT will do the trick but tube specs have to be considered I suppose. OTL headamp or dual duties (amp and headamp).

odyopayl · « **Reply #262 on:** Dec 14, 2005 at 09:50 AM »

Quote from: 2ny on Dec 13, 2005 at 04:34 PM

a 10uf film cap is not that hard to find, however if you insist you must, you can series connect two 22ufd eletcros to form a 10ufd NP cap. do it in a - + + - way or vice versa. you can even put a 1meg resistor at the juction and bias the resistor to polarise the caps.

saan ba gagamitin?

Thanks for the info 2ny. Actually just saw one of my SS Amp with unity gain buffer circuit for the inputs. I'm planning to upgrade the components especially the capacitor o.1uF capacitor NP (ceramic type). Want to replace it with Auricap or Multicap is this substantial? Looks like bias cap for the OPAmp?

"Sorry for the sample 10uf" not real just a sample question.

ATJr. · « **Reply #263 on:** Dec 14, 2005 at 02:05 PM »

a ceramic cap along the signal path is a no-no, replacing it with a film type will definitely be an improvement.

ATJr. · « **Reply #264 on:** Dec 14, 2005 at 02:29 PM »

Quote from: eXg on Dec 14, 2005 at 08:37 AM

O eto naman...

what tubes (or their spec) make good candidates for headphone duties? my mind tells me a separate secondary winding for OPT will do the trick but tube specs have to be considered I suppose. OTL headamp or dual duties (amp and headamp).

there are many to chose from just look them up in the web...

yes, you can put a 600ohm tap at the output secondary along with the regular speaker output, or you can use you preamp for that purpose.

eXg · « **Reply #265 on:** Dec 14, 2005 at 08:23 PM »

other than looking at existing schematics/projects, what specification should i look for in a tube for headamp duties? For instance there are 6As7 OTL headamp -- why does 6As7 make a good tube for headamp?

ATJr. · « **Reply #266 on:** Dec 15, 2005 at 05:58 AM »

Quote from: eXg on Dec 14, 2005 at 08:23 PM

other than looking at existing schematics/projects, what specification should i look for in a tube for headamp duties? For instance there are 6As7 OTL headamp -- why does 6As7 make a good tube for headamp?

there are many out there, 6AS& has very low plate resistance, about 230ohms and therefore can be configured as a voltage amp, with just a coupling capacitor between its plate and the headphone, that is why the term OTL, but otoh it has a mu of only 2, therefore another triode stage is required to get the gains to more practical levels. for instance, a 12au7 with a mu of 17 will give the combination a voltage gain of 34, very nice!

markmlists · « **Reply #267 on:** Dec 16, 2005 at 04:47 PM »

Hi,

Gurus say that it is the 2nd order (or x order) harmonic distortion that give tubes a euphonic, irresistably sweet sound. Will I get/experience/hear that if I use a tube pre-amp with my SS integrated amp?

Thanks in advance.

ATJr. · « **Reply #268 on:** Dec 16, 2005 at 06:41 PM »

Quote from: markmlists on Dec 16, 2005 at 04:47 PM

Hi,

Gurus say that it is the 2nd order (or x order) harmonic distortion that give tubes a euphonic, irresistably sweet sound. Will I get/experience/hear that if I use a tube pre-amp with my SS integrated amp?

Thanks in advance.

why not? ss amps does not introduce these distortion on their own. try it you may like it!

eXg · « **Reply #269 on:** Dec 17, 2005 at 11:17 PM »

Virtual centertapping is done by connecting 1 100R to each tap (AC) and joining the other end of the two resistors. I saw this usually on filaments.

when is it most appropriate to ground the virtual center tap?

Does the resistor value vary with the given voltagesm?