advertisement


A passive sort of guy?

JustJohn

JustJohn

pfm Member
Over the past few years I’ve had a number of amps at the heart of my system, including a Quad 34/306, Nait 3, Brio R, Cyrus 6xp and a few others I might have forgotten. Despite the many good qualities of these amps, I always find myself gravitating back to a trusty old Cyrus One.

The reason is the clear open window it presents on whatever source (CD/vinyl) and music happens to be paying. Its bass may not be the deepest or its treble the most refined, but it puts absolutely nothing in the way of the sound that’s coming out of the speakers. It’s that pin-sharp picture that always draws me in, even though the colour may not be spot-on. Now I’m no technical bod, but I understand this might be a result of its passive pre – it’s essentially a power amp with a cheap volume control attached, as somebody once explained it to me. I should add that I listen at moderate levels, and can understand that if I were to turn up the wick that pinpoint focus might not be so appealing, but that hardly ever happens.

So I can't help wondering what other current integrated amps use a passive pre? The latest Nait, I believe, and the Exposure 2010s2. Any others? And might I reasonably expect them to offer the same sort of sound? That clean, sparkling window onto the music? But presumably with the extra grunt and refinement that comes from an additional 40W or so of power and a more modern internal design? Or am supposing it all wrong…
 
Could be you're on to something.
One of the most fascinating amps I ever had was a Densen DM10 integrated. Complete dual Mono Amp with passive Pre in one box. You might even want to try and find a s/h model of these.

Why it sounds so good I have no idea, especially since in my experience the Pre has the greatest effect to the overall sound.
For example in the past I went from a Linn Waconda to Kairn and also tried Naim 102 to 82, each time the change was dramatic. How can passive Pres sound right then?

I seriously have no clue.

Right now I keep drifting back to my Exposure 23/28, which does everything right, especially over all genres and recording qualities.
Always enjoyable sound. No reason the look further in my eyes.
 
Currently experimenting with passives with some promise.I guess the source component has a lot of bearing on results , impedence matching and all that.I am using a TVC passive , nice treble and mids but maybe a little lacking in bass drive and timing.The jury is still out.
 
Assuming you have an appropriate source and power amp I think passive pres are unbeatable. I have a couple of really good Audio Synthesis stepped attenuator pres and I just don't see how they could be beaten by active electronics assuming a perfect impedance and gain match within the system. It surprises me that you can even hear the differences between resistors and switches etc, but it is certainly there!

PS The Densen Beat 100 is another good passive integrated, as are many modern tube integrateds e.g. Prima Luna Prologues etc. Given 2V is the standard for a modern line input there is just no point in active unless you want tone controls etc.
 
DavidS said:
How do these integrateds implement the passive section ?
Click to expand...

Basically its just a high gain power amp with a nice high input impedance with a source selector and volume pot in the same box. It is a really good way of doing it as you lose the interconnect between a stand-alone passive pre and the power amp, a connection that should ideally be as short as possible.
 
I was recently given a DIY passive pre, removed the jumpers from my NAD 720BEE, plugged it into the inputs, and tried a few different tracks. Has been quite a difference, and really interesting. Now considering different power-amp options. Dynamics, sound staging, and just about everything has improved. Very interesting
 
So reading between the lines, I think it might be fair to assume that the integrated amps with a passive pre are the ones that are more likely to provide the sort of wide-open sound that appeals to me.
 
The problem is one needs to view a passive pre as an interface, it can only work well if the conditions are ideal and is not a universal answer. It requires a low source output impedance, high amp gain and fairly high amp input impedance. Get these right and it is all but unbeatable at any price, get them wrong and it is lifeless, gutless and dead in the water. I'm lucky in that a lot of amps I like (much vintage Leak, Quad etc) are very good candidates for a passive pre, though I do need to choose my sources carefully, e.g. tube phono stages do not work well IME.
 
I did say 'more likely'! But if we're looking at an integrated with a passive pre, is it fair to assume the designer has taken into account the high amp gain, input impedance? (Not that I have any more than the foggiest idea what they actually do.) As for the source output impedance, what would a typical CD player provide?
 
Yes, absolutely. I've yet to find a CD player that doesn't sound great into a passive pre, my only issue has been phono stages. I'd likely move to one in the main system if I found a really good configurable phono stage that was happy driving a passive.
 
Tony L said:
The problem is one needs to view a passive pre as an interface, it can only work well if the conditions are ideal and is not a universal answer. It requires a low source output impedance, high amp gain and fairly high amp input impedance.
Click to expand...

Exactly. Basically the difference between a "passive" (I hate the misleading term, but oh well...) and active pre is that a "passive" pre relies on the source to provide the amplification and buffering.
 
Tony L said:
Yes, absolutely. I've yet to find a CD player that doesn't sound great into a passive pre, my only issue has been phono stages. I'd likely move to one in the main system if I found a really good configurable phono stage that was happy driving a passive.
Click to expand...

It may well not suit you but I use a Creek phono and a Creek passive pre , works well with my MM cart.


Bloss
 
Tony L said:
Yes, absolutely. I've yet to find a CD player that doesn't sound great into a passive pre, my only issue has been phono stages. I'd likely move to one in the main system if I found a really good configurable phono stage that was happy driving a passive.
Click to expand...

That's interesting, because one of the issues I have with the Cyrus One is too much gain with a Rega Exact (around 7mv) into the MM phono stage. The usable volume is only around 7-8 (the same issue with the CD input has been solved with a pair of the excellent Goldenjack attenuators). Though vinyl still sounds great with the Cyrus, I was thinking of trying an external stage, possibly a Rega Fono. But given what you say, what should I look for from an external stage? (Just checked – Rega stats quote an output impedance of 200 ohms. Is that high or low?!)
 
Am interested in a passive pre myself when I finally move completely to FLAC audio. So has anyone tried, and hence can recommend, a passive pre in to active Teddy ST60s via a SNAXO ?

CHE
 
I've come from passive (TVC) to active preamp and i will never go back to passive. Passive kills dynamic of the music. My JOB225 is high sensitive amp but nevertheless need some drive.
M thinking is the passive input impedance put to much load on the opamp
 
... at the exit of the CD playeur. Active gives a better impedance match for the CD player and the amp input
 
That surprises me as, after a quick google, the Job looks ideal for a passive at 0.7v and 51k.

PS Speaking as someone who has spent a lot of time playing with studio compressors, limiters etc dynamics are odd things in that our perception is often reversed in that compression adds punch, slam and impact to the sound and we interpret that as more dynamic range, when it is the opposite. As such I'm prepared to bet in an AB dem many folk would pick the more compressed sound assuming it was really nice clean compression. It is a reason many valve preamps sound so big, powerful and punchy, and why so many of us like them!
 
You must log in or register to reply here.


advertisement


Back
Top