Not really sure where to start with this one, so here goes !!
A couple of months back I refurbished and modified my old Maplin Mos-Fet Amplifiers, Of course I then needed something to drive them with, so built the Rod Elliot P97 Tone control pre amp and Phono Stage.
I had some oscillation problems with the pre amp from the start, a square wave of any frequency would have a large spike at the rising edge of the waveform, this was cured by fitting a couple of 22pf caps across the feedback resistors of the volume op amp, I thought this was problem solved, but now I'm not so sure.
Now I've had chance to spend some time listening to the system in more detail, I've noticed that on both CD and Vinyl the overall sound is very bright, and in particular, S's (esses) and T's on vocals can be over pronounced, and sound very harsh, in some cases with high female vocals and loud cymbals, it can take on a almost metallic sound, and the vocals can drown out the sweet cymbals being played in the background, Does that make sense? This is not how I remember some of my old favourite albums.
I have a pair of Bowers and Wilkins 602 S2 speakers, In reviews they are reported as being quite a bright speaker, so I need a warm sounding amp to tame them down.
As the title implies, I'm looking for some recommendations for a warm sounding second hand amp, to see in I can get things back to how they should sound, while I try and sort out whether it's the Pre Amp, or the old Maplin amps causing the problem.
I had thought about something like the NAD 3020, as that has a pre amp out and pre amp in capability, But I'm open to suggestions.
A couple of months back I refurbished and modified my old Maplin Mos-Fet Amplifiers, Of course I then needed something to drive them with, so built the Rod Elliot P97 Tone control pre amp and Phono Stage.
I had some oscillation problems with the pre amp from the start, a square wave of any frequency would have a large spike at the rising edge of the waveform, this was cured by fitting a couple of 22pf caps across the feedback resistors of the volume op amp, I thought this was problem solved, but now I'm not so sure.
Now I've had chance to spend some time listening to the system in more detail, I've noticed that on both CD and Vinyl the overall sound is very bright, and in particular, S's (esses) and T's on vocals can be over pronounced, and sound very harsh, in some cases with high female vocals and loud cymbals, it can take on a almost metallic sound, and the vocals can drown out the sweet cymbals being played in the background, Does that make sense? This is not how I remember some of my old favourite albums.
I have a pair of Bowers and Wilkins 602 S2 speakers, In reviews they are reported as being quite a bright speaker, so I need a warm sounding amp to tame them down.
As the title implies, I'm looking for some recommendations for a warm sounding second hand amp, to see in I can get things back to how they should sound, while I try and sort out whether it's the Pre Amp, or the old Maplin amps causing the problem.
I had thought about something like the NAD 3020, as that has a pre amp out and pre amp in capability, But I'm open to suggestions.
I Hope so, I should have a restraining order on eBay 
But seriously, I've known about NAD for a long long time, right back to the late 70's, but never owned one, If it sounds as good as the reviews say, I might end up keeping it, once I've resolved what is causing the harshness of my current setup.
But seriously, I've known about NAD for a long long time, right back to the late 70's, but never owned one, If it sounds as good as the reviews say, I might end up keeping it, once I've resolved what is causing the harshness of my current setup.
It has the same harsh sound on both CD and Vinyl, and the same tracks on the CD or Vinyl version.
I think it's the pre amp, but I can't recreate it on the bench, Seems strange that vocals for instance now overpower the finer things going on.
I was thinking of swapping the OPA2134 op amps to the NE5532's used by Rod Elliot, I built the front end of the amp in Multi Sim, and when using the OPA's got the same spike on a square wave as I had with the amp, If I swapped that for the NE5532, No Spike
I think it's the pre amp, but I can't recreate it on the bench, Seems strange that vocals for instance now overpower the finer things going on.
I was thinking of swapping the OPA2134 op amps to the NE5532's used by Rod Elliot, I built the front end of the amp in Multi Sim, and when using the OPA's got the same spike on a square wave as I had with the amp, If I swapped that for the NE5532, No Spike
Also noticed, some time ago actually, I can get little crackles and pops (ON CD !!) this happens sometimes normally only at a quiet start, or passage of music where there are soft vocals, or a few piano notes played, its almost as though these quiet parts set off a small spike or something.
Listening to a variety of music today, it seems as the midrange is way overpowering, With the treble knocked back, so Cymbals are slightly muted, things like Saxophone, Trumpets, etc, still blast through with almost ear piercing clarity.
Listening to a variety of music today, it seems as the midrange is way overpowering, With the treble knocked back, so Cymbals are slightly muted, things like Saxophone, Trumpets, etc, still blast through with almost ear piercing clarity.
Thanks for the reply.
I was thinking possibly speakers myself, but wanted to try a different Pre amp / amp first, as there clearly is a problem with the setup I am running at the moment.
Before I rebuilt my old Mos Fet amps and built the Rod Elliot Pre amp / Phono Stage, I was running a pair of vintage Quad Mono Blocks with the 22 control unit, but I had the opposite problem, Muddy Mid range, Excellent Bass, and Clear highs, So I've really gone from one extreme to the other.
I'll see what the NAD 3020i brings to the party and take it from there.
I've seen others point out that the 602's can be bright, and one suggestion is to replace the Bi Wire link on the speakers with copper cable.
The crossover is built on a PCB, and another suggestion was replacing the 0.47R resistor (I Think) to the tweeter with a 1R ~ 1.5R.
I really wish I'd hung on to my 1970's Goodmans Magisters, 15" Woofer, 3" Mid and soft dome tweeter, they had the ability to make almost anything sound good, well.... back in the day anyway.
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