[jarthel]

aikido (www.tubecad.com) is a design by John Broskie. He sells the PCBs as well.

It is a linestage design but can be converted to headphone amp (http://www.tubecad.com/2006/04/blog0062.htm)

Several people have built the linestage or headphone amp versions and have great results.

The power supply is a simple full-wave rectifier with choke input filter. (LC only) which is then fed to a voltage regulator design found in the RCA Designer's handbook (chap33 figure 33.14: http://img240.imageshack.us/my.php?i...re33147hl.gif)


================================

parts list:

from glass-ware.com
aikido PCB (very high quality. 2x to 2.5 thicker than normal PCB)

============================

from partsconnexion

resistors in the signal path: kiwame 2W

non-essential resistors in the amp: holco/PRP 1/2W

high wattage resistors: mills 5W and 12W varieties

other resistors: holco/PRP 1W

non-essential caps: solen

various tube sockets: 7, 8 and 9 pins

6H30: output tubes on the amp

terminal block: I need this since the power supply will be P2P.

chassis wire: DH Labs

female RCA: cardas

============
from Ebay

(all tubes are NOS)
rectifier tubes: 5U4GB, 5V4G, 5AS4, 5R4YG
pass tubes: 6NS5 russian equivalent to 6AS7G. readings from AA seems the russian 6AS7 are better than the Western versions.
error amplifier tubes: 6SL7GT
voltage reference tube: 5751A
6CG7: input tubes on the amp

output caps: 100uF 370VAC ASC motor runs (metallized polypro in oil)

bypass output caps: russian PIO and russian teflons

power supply cap: 100uF 370VAC ASC motor runs (metallized polypro in oil)
======================
from vt4c.com (HK)
main transformer: rcore if it's too noisy or build quality is poor, might have to get a potted transformer from "silk" in thailand which should be available in 2 months time.)

chassis: aluminum in black. It should look like this http://www.thlaudio.com/image/miscIM...e-PRAL-1cB.jpg

silver solder (from japan)

=================
from THLaudio.com (taiwan) (had good experience with them before but my recent communication with them is just horrible. replies take too long and sometimes unanswered)
choke: James audio

tuning knob: http://www.thlaudio.com/image/knobs/...o-r5025-45.jpg

========================
from Diyfidelity.com.au

attenuator: 100K ladder (diyfidelity.com.au). thinking of getting a proper elma ladder switch (the ones designed for audio. not telling where since stock is very low.

but I want to see the quality of the cheap switch first. it may be good enough. I have paid an extra $10 AUD to get matched resistors.

======================
from RS Compoents (local branch) (haven't ordered these yet since I need to know what stuff are missing so I can order them all at once. I want to save on postage)

secondary transformer: 75VA 2x 0-9 4.17A) for the amp tubes heaters
hex spacers that are threaded on the inside
several Rubycon caps for the heater supply

=======================
from Farnell (local branch)

headphone jack
fuse socket
power switch

====================
from sidewindercomputers.com

cheap IEC sockets with filters! (well at least cheaper that can be had locally)

 

[jarthel]

will take pics of the parts later tonight and tomorrow.

just ordered a "hakko 936" clone. aoyu3 936A. it looks quite similar to the hakko. it is made in china.

==============

The rectifier tubes were chosen for their size. I have a Bendix tube (6X5 substitute) that is much smaller and would probably do the same job but I want to try something different.

according to eric barbour (headwize.com library), the 6as7 family should produce some amazing light show. the 5651 is a voltage reference neon tube but it's in a small package. still thinking if I should show display it or hide it. it would be tiny compared to the rectifier and 6as7.

 

[philodox]

A close friend of mine has built one and will be bringing it to the upcoming Hamilton Head-Fi meet. Keep a close eye out for impressions after this weekend.

 

[Uncle Erik]

Wow, that's a very interesting design. I just put in for the octal PCB and four sockets. Like I really need another project... but at least the PCB won't go bad, and I can piggyback a part for it here and there onto orders for other stuff.

 

[jarthel]

one of the previous blogs contain a schematic for the octal headphone version.

ps. the pcb is so nice since it has multiple pads for 1 component. so users can use various types of caps/resistors without running out of space.

 

[jarthel]

Quote:

Originally Posted by philodox A close friend of mine has built one and will be bringing it to the upcoming Hamilton Head-Fi meet. Keep a close eye out for impressions after this weekend.

could you include info such as:

1. octal/9pin version
2. what output/input tubes are used? what brand? NOS or current production?
3. what type of construction for the tubes? like for the 6cg7 family, there are several types. there's a clear top, chrome top, with shields and etc.

I'm asking since the type of tubes used has dramatic effect on the sound.

thank you.

 

[philodox]

I know that he is using 6H30 and 6CG7, but beyond that I will PM him to answer your questions.

 

[philodox]

He is having a hard time staying logged into head-fi, so emailed me and asked that I post the following: Quote:

1. 9 pin PCB/sockets 2.+3. 6CG7 (NOS) RCA Cleartop on the input - 6H30 (current) Sovtek on the output

I'd like to add that the Sovtek's he is using are the new ones made in the same factory as the new old stock ones. I asked around and there does not seem to be any difference between the two versions... though the old ones are more rare and cost twice as much.

Before building the amp, I PM'ed Earl [our resident tube expert], asking about the 6CG7's and he wholeheartedly recommended the RCA Cleartops. They aren't cheap though.

 

[looser101]

Quote:

Originally Posted by jarthel could you include info such as: 1. octal/9pin version 2. what output/input tubes are used? what brand? NOS or current production? 3. what type of construction for the tubes? like for the 6cg7 family, there are several types. there's a clear top, chrome top, with shields and etc. I'm asking since the type of tubes used has dramatic effect on the sound. thank you.

1. 9 pin PCB/sockets
2. 6H30/6CG7
3. 6H30 Sovtek current stock / 6CG7 NOS RCA Cleartop

-r-

 

[philodox]

Ah, there he is. Here is a picture that he sent along as well.

 

[looser101]

Website under construction - no updates until next week

http://renatod.googlepages.com/home

-r-

 

[jarthel]

I have 2 pairs of rca clear tops, 1 pair of rca chrome and 1 pair of sylvania. I got the sylvania just because someone in AA said he liked it better than a cleartop. wouldn't hurt to roll it in.

============

to looser:

what power supply config are you using?

also is that an output transformer you're using? how did you connect it? can you tell me what type of hammond transformer is it? thanks

 

[philodox]

Renato is having some difficulty posting again, so I will act as proxy: Quote:

Power supply is on the website with the following changes: no diode across choke (kills bass response), 220uf Electrolytics Output transformers are Hammond 119DA's (to drive my Grados), out of the output caps to ground (tranny input 600ohm connection to C1 output, tranny input 0ohms to signal ground)

 

[looser101]

Quote:

Originally Posted by jarthel I'm asking since the type of tubes used has dramatic effect on the sound.

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-

 

[jarthel]

I haven't build mine yet. still waiting for parts.

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.