Home » Audio » Group Build » Ohm Sweet Ohm
Re: Steve Brown and I are working on this amp [message #31959 is a reply to message #31958] Wed, 13 September 2006 14:07 Go to previous messageGo to next message
Damir is currently offline  Damir
Messages: 1005
Registered: May 2009
Illuminati (2nd Degree)
Direct coupling has a large advantages - omiting of the coupling cap and grid choke, driver "sees" very high impedance of the output tube grid as a load, etc. Less safe and large B+ are "drawbacks"...
I considered similar circuit ("classic" SE, not parafeed), 2A3 (AD1, etc.) direct-coupled with CCS-ed 6SN7 as a driver. With convential OP (250V/-45V/60mA) input sensitivity is about 1,5Vrms...but, B+ is about 550V.
Probably, sonic "plus" gained with omitting cap/grid choke combo is a large enough to accept high voltage...just a few thoughts.

Anyway, keep us posted about your progress, seems like a interesting amp/circuit. Is the driver paralleled ECC81?


Re: Steve Brown and I are working on this amp [message #31960 is a reply to message #31958] Wed, 13 September 2006 17:51 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey-Hey!!!,
Nice looking project. Do watch out for Iron-Iron coupling with that many pieces. I have simplified some of my designs by putting all the power and filament in the same direction, and all the signal in the other. The para-feed makes things a bit mroe interesting, 'cause it is working in the same phase, yet still needs to be seperate.

Let us know how it works.
cheers,
Douglas

Re: Ohm Sweet Ohm [message #31961 is a reply to message #31949] Wed, 13 September 2006 22:44 Go to previous messageGo to next message
Forty2wo is currently offline  Forty2wo
Messages: 163
Registered: May 2009
Master
Finaly going on the 6a5 P-P project...John

Ah there we go [message #31962 is a reply to message #31961] Wed, 13 September 2006 22:47 Go to previous messageGo to next message
Forty2wo is currently offline  Forty2wo
Messages: 163
Registered: May 2009
Master

.

Re: Ohm Sweet Ohm [message #31963 is a reply to message #31957] Thu, 14 September 2006 00:23 Go to previous messageGo to next message
Forty2wo is currently offline  Forty2wo
Messages: 163
Registered: May 2009
Master

Hi M,

I am listening mostly to the recent D3a, 300B amps.( note to Damir I tired 6688 and E180 and the d3a is the clear winner in my application . Will try the C3~ if I come across any )

Next up is a P-P amp 6a5’s (in the 2A3 family). I had almost decided to go with Douglas’s Galahad front end, and that is the fallback plan, if this doesn’t work out.

But I got to thinking, I like my Aikido line stage. So with a bit more gain… then I acquired a set of transformer phase spliters. Well we’ll see.

As to chassie, I love a good found object. Or if I have really settled on something, then it’s time to move it into a finished form but for me this rarely happens. I have a very nice set of wood boxes (found ) that the DRD45 will move into one day. In the mean time I use cakepans as a half way between naked breadboard and finish amp.

They cost $6, are very easy to cut/drill, keep the HT mostly under and if you use a little care, look somewhat respectable. When faced with $110 of nice chassie, you have to measure to the last mm. With a found object, lay it down and drill it, if you screw up, well it’s off to Hellmart with another $6.

I find that the separating the "let’s be real careful with the inlay" allows me to do a better design and layout.

It’s late I will get to your other questions later…John


Re: Ah there we go [message #31964 is a reply to message #31962] Thu, 14 September 2006 09:36 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Wow; that is some kind of fine. A cake pan; perfect. I saw that done in an old Sound Practices mag and it's a great solution to exorbitant priced enclosures; and... comes with handles!. Is there good room inside for making changes to the circuit and such?

Re: Ohm Sweet Ohm [message #31965 is a reply to message #31963] Thu, 14 September 2006 09:45 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Man; I love to see practicle use of ordinary stuff as chassis and enclosure duties. That way stuff gets built instead of dreamed. And I find that people get more involved with the sound of the unit and less worried about what it looks like.
I just picked up the three way pots from Broskie for the Akido LS. They are on sale for 29$.
Thanks for the cake pan remminder. How are you finding the prices of the big triodes lately? They seem to be rising.


Re: Ah there we go [message #31984 is a reply to message #31964] Sun, 17 September 2006 21:06 Go to previous message
Forty2wo is currently offline  Forty2wo
Messages: 163
Registered: May 2009
Master
This is actually a broiler pan. I needed the much heavier steel, to support the unusually large iron load, 18# for the PS trans alone.

The down side is they are harder to work. I am still using a hole saw to cut the tube sockets. A 1 1/8" will go through a cakepan like cheese. With the broiler pan, I needed cutting oil and time.

The upside, they are 3" deep and damn near bullet proof…John


Previous Topic: Heyboer
Next Topic: WOW
Goto Forum:
  


Current Time: Thu Nov 14 18:05:26 CST 2024

Sponsoring Organizations

DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Miller Audio
Miller Audio
Tubes For Amps
TubesForAmps.com

Lone Star Audiofest