[philodox]

Note: The part of the amp schematic with the dashed line around it (not on PCB) is not necessary with this PSU since the High Voltage (+150V) can be adjusted with the resistor (R*) after the bridge rectifier.

 

[looser101]

Quote:

Originally Posted by jarthel a 7308 has less microphonics than a 6DJ8. I doubt a good design can cancel out this microphonics since this in inherent to the tubes.

Agreed. This is a mechanical issue that cannot be resolved by circuit topology.

-r-

 

[jarthel]

Quote:

Originally Posted by philodox Note: The part of the amp schematic with the dashed line around it (not on PCB) is not necessary with this PSU since the High Voltage (+150V) can be adjusted with the resistor (R*) after the bridge rectifier.

It is advisable to use regulation or other means (smaller cap, more chokes) than using a resistor to lower target voltage. it seems high impedance supply is not desirable.

 

[jarthel]

if anyone is after NOS 6h30, they are available in the tubestore.com for around $50 each. an extra 5% (I think) for matched pair.

 

[philodox]

Quote:

Originally Posted by jarthel if anyone is after NOS 6h30, they are available in the tubestore.com for around $50 each. an extra 5% (I think) for matched pair.

As I said earlier, these are a waste of money as they sound identical to the new tubes which are made in the same factory and to the same specs. You can get them at parts conneXion for much less than $50 each and they only charged me $5 flat for tube matching on a quad [works out to $1.25 per tube].

EDIT: Just checked, they are $19 bucks each.

 

[jarthel]

Quote:

Originally Posted by philodox As I said earlier, these are a waste of money as they sound identical to the new tubes which are made in the same factory and to the same specs. You can get them at parts conneXion for much less than $50 each and they only charged me $5 flat for tube matching on a quad [works out to $1.25 per tube]. EDIT: Just checked, they are $19 bucks each.

there is a russian site somewhere with close-up photos of the internal construction of the NOS and new Sovtek tubes. The NOS has different internal construction.

ps. it's $25+ for the gold-pin version (which is the one that I got)

 

[philodox]

Quote:

Originally Posted by jarthel The NOS has different internal construction.

Gold pin version? Don't they all have gold pins? Where did you get your 6H30s? They are around $30 MSRP, but parts connexion offers them for substantially less. Might be the same tubes.

Anyways... the construction may be slightly different, but according to 3 different head-fi'ers who contacted me when I asked around about this a while back they sound the same.

 

[jarthel]

Quote:

Originally Posted by philodox Gold pin version? Don't they all have gold pins? Where did you get your 6H30s? They are around $30 MSRP, but parts connexion offers them for substantially less. Might be the same tubes. Anyways... the construction may be slightly different, but according to 3 different head-fi'ers who contacted me when I asked around about this a while back they sound the same.

if you really look at the pcx website, there are 2 versions that they sell. non-gold pins and gold pins.

Quote:

Originally Posted by philodox the construction may be slightly different

they internal construction is not just slightly different if you actually see the photos.

 

[philodox]

Quote:

Originally Posted by jarthel if you really look at the pcx website, there are 2 versions that they sell. non-gold pins and gold pins.

Ah yes, under the Electro Harmonix section. Either way they are all made in the same Sovtek factory as far as I know... I wonder if the gold pins really make a difference? I doubt it. Quote:

Originally Posted by jarthel they internal construction is not just slightly different if you actually see the photos.

Care to point me to them? All I am saying is that they are supposed to sound identical. Does it matter what they look like???

 

[jarthel]

Quote:

Originally Posted by philodox Care to point me to them?

I can't really remember. I just searched the net and came across the site.

 

[looser101]

Just in case someone is interested in building an Aikido based headamp the PCB's are on sale until July 21, 2006.

-r-

 

[tkam]

The current production and NOS 6h30 sure sound identical to these ears. However I could see there being some quality variance amongst the current production ones as the QC process they go through is much looser than what the NOS ones went through.

 

[philodox]

Quote:

Originally Posted by tkam However I could see there being some quality variance amongst the current production ones as the QC process they go through is much looser than what the NOS ones went through.

Thanks for chiming in Todd.

I don't think that the quality variance is poor at all with the new stock 6H30's... part of the reason that parts connexion only charges a $5 flat rate for a matched quad rather than their usual $5 per tube is that matching a quad is as simple as 'grabbing 4 tubes out of the box' according to their man on site. He still tests them fully and makes sure they are a match, but rarely has to swap a tube out.

 

[drarthurwells]

Quote:

Originally Posted by looser101 I'm not sure this true. Some people claim that a well designed tube amp shows little effect from tube rolling. If I remember correctly John Broskie also mentioned that the Aikido design shows little effect to the sound by tuberolling. Since you have a nice selection please let us know if this is true. Curious minds want to know. -r-

I would think the opposite is true.

Some tube amps (the Raptor) do tend to sound the same with different tubes - their design constrains the tube to force it to behave along narrowly defined parameters.

Other tube amps impose less contraints and allow the tubes to do their thing, and the sound changes dramatically with tube changes.

 

[jarthel]

some photos

===========
photo of the power supply cap (2.5in D x 4+in H)

got 2 more of these coming for the output

http://img209.imageshack.us/my.php?i...4medium1ab.jpg
============
photo of the cheapo ladder attenuator (vishay-dale RN55C)

http://img210.imageshack.us/my.php?i...5medium8uy.jpg
==========
photo of the non-essential caps

all are solens

http://img209.imageshack.us/my.php?i...8medium1ds.jpg
=============
photo of the matched resistors for the attenuator

http://img218.imageshack.us/my.php?i...1medium7rp.jpg
===========
photo of some of the resistors

I bought extra resistors so I can get matching pair. these will be the ones that has been taped together.

the big one would be the Mill wirewound 12W 100ohm.

red resistors = PRP
green resistors = Kiwame

http://img210.imageshack.us/my.php?i...7medium9xs.jpg
==============
photo of the 5651A neon voltage reference tube

http://img210.imageshack.us/my.php?i...1medium6tj.jpg
================
photo of the tube rectifiers

from the left:

Tungsol 5V4G, Phillips Miniwatt 5AS4 and Sylvania 5U4GB (3 more tubes to come for the rectifier)

http://img210.imageshack.us/my.php?i...3medium3ge.jpg
=====================
photos of the gold-pins Sovtek 6H30

http://img214.imageshack.us/my.php?i...6medium1pi.jpg
=======================
some of the 6cg7 tubes

http://img210.imageshack.us/my.php?i...9medium1kf.jpg