Best phono / line preamp

2KW · 21st May 2007, 06:37 AM

Hello,

I wish to build a tube preamp for my LP's and CD's. driving into a large Mosfet power amp.

Is the AKIDO line amp better than the one designed by Fred Nachbar ?? Has anyone built both?

Fred's amp

Akido

Thanks,

Paul.

Geek · 21st May 2007, 07:25 AM

Hi,

I've heard Fred's (I think I have it somewhere here) and several I built along with some from other DIY'ers, but not an Aikido pre (working on one as we speak though

).... bottom line, IMO, is they all have their charm.

Cheers!

rajucc · 26th December 2011, 04:04 AM

Quote:

Originally Posted by 2KW

Hello,

I wish to build a tube preamp for my LP's and CD's. driving into a large Mosfet power amp.

Is the AKIDO line amp better than the one designed by Fred Nachbar ?? Has anyone built both?

Fred's amp

Akido

Thanks,

Paul.

Do you build your Akido Phono ?

Eli Duttman · 26th December 2011, 01:38 PM

2KW,

The line stage you use is governed by what drive voltage the MOSFET power amp needs to yield full O/P. If that voltage is less than 2 VRMS, a buffered volume control, plus source switching, is in order. If it's a bit more than 2 VRMS, a low gain design, like those built around 12B4s. What makes 2 VRMS a "magic" number is the fact that that is the full O/P of a "standard" CDP.

Check the spec's of the FET power amp and report back with its drive voltage requirements.

andyjevans · 27th December 2011, 08:32 AM

Look at the thread "26 pre amp". The 26 is considered by its many users to be the best preamp tube ever made. The thread gives total instructions for how to build it. You'll need a step-down OPT like the Lundahl LL1660/5mA in 4.5:1 or a plate choke and parafeed OPT. A transformer out will give you SE or PP drive possibilities. It's all in the thread. 26 are easy to get on ebay or from dealers - a large amount were made.

Andy

DualTriode · 27th December 2011, 03:45 PM

I do not know Fred’s amplifier. Looking at the Fred link above all I see is words, not a circuit diagrams to be seen.

I have built several versions of the Aikido including the Aikido Phono preamplifier.

The combination of pre and line amplifiers I ended up with sitting on the table in the listening room is the Aikido Phono preamplifier, stepped attenuator, Aikido Cathode Follower (buffer) driving whatever power amplifier. Placing the volume control between buffers seems to be key. The low output impedance of the ACF directly imputing into the power amplifier really kicks butt (slam, kicks hard and fast).

The Aikido line amplifier like most preamplifiers these days has way too much gain IMHO. Where I like the Aikido line amplifier is driving headphones. I use 6BK7’s at the output position. Use the 57 ohm cathode resistor shown in the data sheet. Talk low output impedance and huge gm.

DT

beetel · 30th December 2011, 07:29 AM

Quote:

Originally Posted by DualTriode

I do not know Fred’s amplifier. Looking at the Fred link above all I see is words, not a circuit diagrams to be seen.
DT

Fred's Circuit........

http://www.dogstar.dantimax.dk/tubes...cs/phono-l.gif

rajucc · 31st December 2011, 04:47 AM

Which Aikido Line stage is best for Tetra Sans PS Phono.

Joshua_G · 31st December 2011, 11:57 AM

IMHO, the best phono stage and pre-amp are those by the late Allen Wright. Either FVP5A for single ended, or RTP3C for balanced: Schematics .

grhughes · 31st December 2011, 01:27 PM

I don't like either one. I'd seriously look at Steve Bench's audio website. I built the 12ay7-6922 cascode as a phono. Eight tubes as a preamp (aikido) is a little too much and I like simplicity.

21st May 2007, 06:37 AM	#1
2KW diyAudio Member Join Date: Jan 2007	Best phono / line preamp Hello, I wish to build a tube preamp for my LP's and CD's. driving into a large Mosfet power amp. Is the AKIDO line amp better than the one designed by Fred Nachbar ?? Has anyone built both? Fred's amp Akido Thanks, Paul.

26th December 2011, 01:38 PM	#4
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	2KW, The line stage you use is governed by what drive voltage the MOSFET power amp needs to yield full O/P. If that voltage is less than 2 VRMS, a buffered volume control, plus source switching, is in order. If it's a bit more than 2 VRMS, a low gain design, like those built around 12B4s. What makes 2 VRMS a "magic" number is the fact that that is the full O/P of a "standard" CDP. Check the spec's of the FET power amp and report back with its drive voltage requirements. __________________ Eli D.

31st December 2011, 01:27 PM	#10
grhughes diyAudio Member Join Date: Mar 2005 Location: Cubicle Sweet Cubicle, SW, MO, USA	I don't like either one. I'd seriously look at Steve Bench's audio website. I built the 12ay7-6922 cascode as a phono. Eight tubes as a preamp (aikido) is a little too much and I like simplicity. __________________ "The gift of imagination is the gift of the gods imparted to a few for which they receive innumerable kicks in the a$$ their entire life." Le Corbusier (Edward Jenneret)

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21st May 2007, 07:25 AM	#2
Geek diyAudio Member Join Date: Sep 2004	Hi, I've heard Fred's (I think I have it somewhere here) and several I built along with some from other DIY'ers, but not an Aikido pre (working on one as we speak though ).... bottom line, IMO, is they all have their charm. Cheers!

27th December 2011, 08:32 AM	#5
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	Look at the thread "26 pre amp". The 26 is considered by its many users to be the best preamp tube ever made. The thread gives total instructions for how to build it. You'll need a step-down OPT like the Lundahl LL1660/5mA in 4.5:1 or a plate choke and parafeed OPT. A transformer out will give you SE or PP drive possibilities. It's all in the thread. 26 are easy to get on ebay or from dealers - a large amount were made. Andy

27th December 2011, 03:45 PM	#6
DualTriode diyAudio Member Join Date: Aug 2009 Location: Sacramento	I do not know Fred’s amplifier. Looking at the Fred link above all I see is words, not a circuit diagrams to be seen. I have built several versions of the Aikido including the Aikido Phono preamplifier. The combination of pre and line amplifiers I ended up with sitting on the table in the listening room is the Aikido Phono preamplifier, stepped attenuator, Aikido Cathode Follower (buffer) driving whatever power amplifier. Placing the volume control between buffers seems to be key. The low output impedance of the ACF directly imputing into the power amplifier really kicks butt (slam, kicks hard and fast). The Aikido line amplifier like most preamplifiers these days has way too much gain IMHO. Where I like the Aikido line amplifier is driving headphones. I use 6BK7’s at the output position. Use the 57 ohm cathode resistor shown in the data sheet. Talk low output impedance and huge gm. DT

31st December 2011, 04:47 AM	#8
rajucc diyAudio Member Join Date: Aug 2011	Which Aikido Line stage is best for Tetra Sans PS Phono.

31st December 2011, 11:57 AM	#9
Joshua_G diyAudio Member Join Date: Nov 2008 Location: Israel	IMHO, the best phono stage and pre-amp are those by the late Allen Wright. Either FVP5A for single ended, or RTP3C for balanced: Schematics .

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