Tubes amp

[Kippei 0]

Acutally that price is common all around US. What interest me is the shipping rate...

[siriuz 0]

hey squalle, you asked why NOS tubes were preferred? i came across this tube FAQ on headfi during some googling

 

3.4 $3000 for a single tube??! Why are some NOS tubes so expensive?

 

The short answer - supply and demand.

 

The long answer - Some tube amps are quite old, and their owners may prefer to maintain a completely `vintage' setup. Others believe NOS tubes sound better. Others are simply sheep with too much money to throw around who jack up the prices.

 

The NOS tube supply by its very nature finite - and dwindling each day. Some NOS tubes are very much sought after and are hence in particularly short supply. All these factors contribute to the much higher prices of NOS tubes when compared to plain new stock tubes.

 

You may want to consider what types of tube an amplifier uses before purchasing it - this WILL more or less determines the scale of your future expenditure when re-tubing the amplifier.

 

3.5 Do NOS tubes really sound better?

 

NOS tubes are reputed to sound much better than new stock tubes. The author of this guide believes, to a certain extent, that this is true. There are many theories floating around as to why NOS tubes sound better. I have cherry-picked a few that I am certain have at least a grain of truth in them.

 

1. The 1930s-1950s were the golden era of tubes. Equipment used to manufacture tubes and more importantly, skilled people to operate them were plentiful. All of these have been lost with the advent of the transistor and automation.

 

2. Tube R&D has come to a virtual standstill since the 1960s.

 

3. When compared to transistors, tubes are relatively expensive and time-consuming to manufacture (to achieve a good vacuum for a SINGLE tube, some vacuum pumps run for as long as 3 days!). In the highly competitive niche market for new stock tubes, quality may not be the top priority anymore. One amplifier manufacturer has been quoted as having to reject 1 in 4 6AS7 tubes for bundling with their amps due to unacceptable levels of microphonics/hum/channel imbalance!

 

Even then, it is strongly recommended that you try at least a few tubes of recent make before putting down some serious money for NOS tubes. Typically for the price of a single NOS tube you would be able to obtain at least 3-5 new stock tubes. You never know what you might stumble across...

 

read the whole FAQ here: http://www4.head-fi.org/forums/showthread.php?t=121357

Edited January 15, 2006 by siriuz

[kross 0]

haha....is there a topic of "soha vs mhha" on headwise? anyway, i might be trying soha when i have the time and resources but right now, i'll enjoy my mhha first before considering building soha.

 

 

[kross 0]

wow...din know that this thread has come so far...to the extend that you guys are ordering tubes from overseas....are the tubes meant for SOHA? if so is it too late to join in now??

[siriuz 0]

yea the tubes would be for the SOHA. yes its too late since there are only 3 tubes in the lot

[Kube 0]

Erm...I can see that I'm entering pretty late into this thread here...but an tube amp really intrigues me..

 

Just finished my cmoy 2, and hungry for another amp (damn this forum! )...

Some questions though...what kind of boards did you use? Schematic for the SOHA I can find, but it seems very complicated for a stripboard or even p-t-p soldering...but is that how you guys did it?

[siriuz 0]

yea from what i've seen of the pictures and what i've heard in the thread, both squalle and kippei using "stripboard". not really "stripboard" since the traces are not strips? i think they're using perfboard / veroboard / <insert variant here>.

 

i dont think its really that complicated if you lay it out nicely on paper first =P

 

since it intrigues you, why not try it?

[squalle 0]

perfboard to be exact

 

soldering was done p-t-p

rather simple as it doesnt involve that many components, and mostly are big components. none is like those 24pins IC or something

 

for layout, you can always refer to what I've done. I posted the pic somewhere

but dun follow my 1st unit, follow my 2nd unit. a lot neater and took out some unnecessary parts

 

kross: we can always meet up and let u try my SOHA u know

 

siriuz: yeah read that last night. didnt realise there were stickies ! haha

btw adhoc is a senior member here also I think,if they belong to the same person anyway

 

btw, remember, put the on/off switch and trafo far away k?

 

anything else, just feel free to ask me here or pm you

 

ADD: here's the price quotes of tubes from Frankie of http://www.wellaudiolab.com/

 

12AU7/CV4003 Mullard $50.00 each NOS box plate.

 

12AU7 clear top RCA NOS $55.00 each

 

12AU7/ ECC802s Tesla NOS 70’s $35.00 each

 

12AU7/5814 GE NOS $18.00 each

 

12AU7 EH $10.00 each

 

12AU7 EH Gold $16.00 each

Edited January 15, 2006 by squalle

[siriuz 0]

i didnt realise that was a sticky either !

i found it on google LOL

[siriuz 0]

i going down to sls tmr to get the parts for the psu section, will finish psu section tmr, then wait until tubes arrive then i work on the other part.

 

heres the parts list i've worked out for the psu section:

 

4 x 100uf 100v electrolytic caps

3 x 470uf 35v electrolytic caps

3 x 47uf 16v electrolytic caps

2 x rectifier bridges

2 x 1N4002 diodes

1 x 15-0-15 200mA transformer

1 x 7812 12v regulator

1 x 7912 -12v regulator

1 x LM337 regulator

1 x 2W TO-220 heatsink (for LM337)

1 x 2k2 resistor

1 x 1k3 resistor

1 x 11k resistor

 

 

the 470uf caps i was thinking 35v abit low since 30v x 1.41 is 42.3v

so i'll probably get 50v ones instead, dont think they'll cost alot more and it wont hurt either

 

if you're wondering where the RLED and the LED went, i decided to put it in the amp section

 

if there are any mistakes in the parts list please let me know

[kross 0]

hmmm...the current production EH tubes seems resonable. why do you guys need to buy from overseas?

[siriuz 0]

because of this review

http://www.sgheadphones.net/index.php?show...indpost&p=60605

[squalle 0]

no, dont put the LED onto the amp part

 

tap from the heater side

 

hmm, ppl always avoid tapping LED current off the amp side

especially those small 7xL12 can only supply 100mA

so better not load those small regulators

 

I didnt put any LED onto mine as you would know that it's on due to the glow from the tube.

unless you wanna light up ur tube using blue LED.

 

the 470uF at 35v is OK. I've got none of them blowing up

and no, it's not seeing 30v * 1.414. it's 15volt AC there

coz u take the + side and the - side. not both going thru the regulator together.

that's why dual supply. one 15v, another is -15v

dont oversize things

it's going to cost you

 

maybe if u want, change the 100uF 100v, one of them to 470uF/100v. one of the cap is to filter AC to make it DC. the one that supply 60v at the end of it. but to warn u first, those rated at 100v, can really go real big in size

[siriuz 0]

oh ok!

i thought it'd be getting the full 30v

 

i mean, i'll be putting it together with the amp side because it'll be on the amp board. it'll still be tapped from the heater supply. yes i want a mean blue glow lighting up my tube

[Kube 0]

Erm...siriuz...are you going to include Da Blok into the heater? Excuse my short-handed words, the heater is the PS, right? Saw your list, and decided to follow it!