Forums

Audio Amplifiers

Started by Cursitor Doom August 28, 2016
Hi all,

What is the best configuration for those first crucial one or two stages 
of an audio amplifier? I mean when you're dealing with the very low 
signal levels you typically get with phono cartridges (anyone remember 
them? - they're making a comeback!) in particular wrt to minimising noise 
and distortion? What's best for the front end? Are we talking long-tailed 
pair or something more involved? I'm well out of date on the subject.

cheers.
Cursitor Doom wrote:
> > > What is the best configuration for those first crucial one or two stages > of an audio amplifier? I mean when you're dealing with the very low > signal levels you typically get with phono cartridges (anyone remember > them? - they're making a comeback!) in particular wrt to minimising noise > and distortion? What's best for the front end? Are we talking long-tailed > pair or something more involved? I'm well out of date on the subject. >
** For a regular, moving magnet phono PU, an RIAA pre-amp/equaliser stage using an audio op-amp like the NE5534 is hard to beat. Very low noise, very low THD and easy to use. You get two in the same pack if you buy the NE5532. Couple of dollars a piece. .... Phil
On 28/08/16 14:36, Cursitor Doom wrote:
> Hi all, > > What is the best configuration for those first crucial one or two stages > of an audio amplifier? I mean when you're dealing with the very low > signal levels you typically get with phono cartridges (anyone remember > them? - they're making a comeback!) in particular wrt to minimising noise > and distortion? What's best for the front end? Are we talking long-tailed > pair or something more involved? I'm well out of date on the subject.
Google for "Douglas Self"; he did some good work in the 70s and 80s.
Den søndag den 28. august 2016 kl. 16.29.43 UTC+2 skrev Tom Gardner:
> On 28/08/16 14:36, Cursitor Doom wrote: > > Hi all, > > > > What is the best configuration for those first crucial one or two stages > > of an audio amplifier? I mean when you're dealing with the very low > > signal levels you typically get with phono cartridges (anyone remember > > them? - they're making a comeback!) in particular wrt to minimising noise > > and distortion? What's best for the front end? Are we talking long-tailed > > pair or something more involved? I'm well out of date on the subject. > > Google for "Douglas Self"; he did some good work in the 70s and 80s.
http://www.douglas-self.com/ampins/ampins.htm
On Sun, 28 Aug 2016 13:36:32 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

>Hi all, > >What is the best configuration for those first crucial one or two stages >of an audio amplifier? I mean when you're dealing with the very low >signal levels you typically get with phono cartridges (anyone remember >them? - they're making a comeback!) in particular wrt to minimising noise >and distortion? What's best for the front end? Are we talking long-tailed >pair or something more involved? I'm well out of date on the subject. > >cheers.
It's been a few years since I rolled my own preamp, but, IIRC, the first stage (bipolar) should have low VCE and low IC for best noise. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I'm looking for work... see my website.
On Monday, August 29, 2016 at 12:08:25 AM UTC+10, Phil Allison wrote:
> Cursitor Doom wrote: > > > > > > What is the best configuration for those first crucial one or two stages > > of an audio amplifier? I mean when you're dealing with the very low > > signal levels you typically get with phono cartridges (anyone remember > > them? - they're making a comeback!) in particular wrt to minimising noise > > and distortion? What's best for the front end? Are we talking long-tailed > > pair or something more involved? I'm well out of date on the subject. > > > > ** For a regular, moving magnet phono PU, an RIAA pre-amp/equaliser stage using an audio op-amp like the NE5534 is hard to beat. Very low noise, very low THD and easy to use. You get two in the same pack if you buy the NE5532. > > Couple of dollars a piece.
And it's all long-tailed pairs in the input stages. -- Bill Sloman, Sydney
On Sun, 28 Aug 2016 07:08:18 -0700, Phil Allison wrote:

> ** For a regular, moving magnet phono PU, an RIAA pre-amp/equaliser > stage using an audio op-amp like the NE5534 is hard to beat. Very low > noise, very low THD and easy to use. You get two in the same pack if you > buy the NE5532.
Very tempting. But this is a personal project/challenge so I don't want it all done for me. Spoils the fun! I've got a stack of old toobz (EL83s?) that are fetching silly money on ebay these days (thanks to the 2nd harmonic distortion revival :)) that I plan to use in the final stages for that "warm toob" sound. Wouldn't seem right using an op amp at the front end under the circumstances. Wanna go retro.
On Sunday, August 28, 2016 at 9:36:38 AM UTC-4, Cursitor Doom wrote:
> Hi all, > > What is the best configuration for those first crucial one or two stages > of an audio amplifier? I mean when you're dealing with the very low > signal levels you typically get with phono cartridges (anyone remember > them? - they're making a comeback!) in particular wrt to minimising noise > and distortion? What's best for the front end? Are we talking long-tailed > pair or something more involved? I'm well out of date on the subject. > > cheers.
For what it's worth there was a company years ago called PS audio that was renowned for their preamps -- maybe there's a schematic somewhere ?
On 8/28/2016 11:13 AM, Cursitor Doom wrote:
> On Sun, 28 Aug 2016 07:08:18 -0700, Phil Allison wrote: > >> ** For a regular, moving magnet phono PU, an RIAA pre-amp/equaliser >> stage using an audio op-amp like the NE5534 is hard to beat. Very low >> noise, very low THD and easy to use. You get two in the same pack if you >> buy the NE5532. > > Very tempting. But this is a personal project/challenge so I don't want > it all done for me. Spoils the fun! I've got a stack of old toobz > (EL83s?) that are fetching silly money on ebay these days (thanks to the > 2nd harmonic distortion revival :)) that I plan to use in the final > stages for that "warm toob" sound. Wouldn't seem right using an op amp at > the front end under the circumstances. Wanna go retro. >
The guys here are very sharp, but they are not mind readers. Couldn't you have mentioned these requirements in your OP?
On 08/28/2016 12:13 PM, Cursitor Doom wrote:
> On Sun, 28 Aug 2016 07:08:18 -0700, Phil Allison wrote: > >> ** For a regular, moving magnet phono PU, an RIAA pre-amp/equaliser >> stage using an audio op-amp like the NE5534 is hard to beat. Very low >> noise, very low THD and easy to use. You get two in the same pack if you >> buy the NE5532. > > Very tempting. But this is a personal project/challenge so I don't want > it all done for me. Spoils the fun! I've got a stack of old toobz > (EL83s?) that are fetching silly money on ebay these days (thanks to the > 2nd harmonic distortion revival :)) that I plan to use in the final > stages for that "warm toob" sound. Wouldn't seem right using an op amp at > the front end under the circumstances. Wanna go retro. >
Well, a 1960-style solution is a long tailed pair built from both halves of a 12AX7A. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net