pre amp

thanks guys....."A few reviews have indicated similar opinions, and one chap went as far as to compare it to a passive design (but with gain)"...what does with gain mean?.....also , as there are now 2 x sets of interconnects required for cd to pre and pre to power, does this degrade quality....IE I have a pair of zanash' super iCs but then a pair of vdh ultimates as my second pair.....where do i put the better pair?(cd to pre OR pre to power...and does this mean I will need to match my Zanash' IC buy buying a matching pair or risk losing quality.....(saying this the vdh are pretty good)

 

Not necessarily..... in my opinion if you have a number of sources the best ic cables should go between pre and power. As all sources will benift ....In your case its just the wadia ...so the best cable goes from the wadia to the pre ...the introduction of the van de huls [with there very odd distortion/edge on the vocals] will be problematic ..but for a simple test of the effectiveness of passive pre you should be able to get some meaningful results ...it just may not be the ideal situation long term ....if you borrow either one of my passives I'll see if I can't drop a cable in thats closer to the on you have.

 

passive

Banpe

I've been using passives since the late 80's and am hooked. If you don't need all the traditional features of a pre-amp eg tone controls, tape loops etc and your sources have a sufficient output, they are definitely worth investigating. They are typically very accurate, but can be a little lifeless depending on the model chosen.

Because they are pretty simple in concept, many people construct their own, but you can also find kits, "assembled kits", fully-finished units sold direct and fully-finished units sold via distributors and retailers. Each route has its advantages and disadvantages.

As has already been mentioned, there are two basic types in general use A) resistive and B) transformer based (TVC)

A) Resistive: Again these come in several flavours
A.1) Based on a potentiometer: These give an (almost) continuous variation in attenuation. Very easy to construct for yourself, but there are some very well-respected, fully-finished units. QED used to make a version which was very cheap.
A.2) Stepped attenuators: These use a switch and a series of resistors to reduce the signal. Again there are two types!
A.2.a) A string of resistors are wired in series with taps in between. The switch just selects one of these taps. A potential disadvantage is the number of solder joints the signal has to pass through
A.2.b) Stepped ladder attenuators: In the switch is arranged such that there are only ever two resistors in the path of the input signal and one in path of the ouput signal. This is theoretically better, but whether it is so in practice is another matter. This type uses more resitors is so potentially more expensive if you are using fancy resistors.

A key decision here is the value you choose; 10kohm or 20kohm are typical for solid-state amps. The higher the value, the easier it is for your source to drive, but the more risk of rolling-off high frequencies- particularly if you use high capacitance interconnects from your pre to the power amp.

B) TVC:
The main advantage claimed for TVCs is that they do a better job with impedence matching, so less chance of high-frequency loss.
Again two types.
B.1) Based on autoformers. There is one coil and the output is taken from various taps along its length.
B.2) Based on tranformers. These potentially offer: complete iisolation ftom the incoming signal, eathing flexibility, conversion from balanced to unbalanced and vice versa, and even gain ie the signal can be amplified passively.

I'd be inclined to start with some thing simple and cheap, if you have to buy, or whatever you can borrow to get a bit of a feel for passives and then decide which of the various flavours you want to try.

FWIW (for what its worth) I started with a very cheap QED based on a potentiometer (still kicking around somewhere), then moved on to a stepped ladder attentuator with fancy components and an awful Hammond enclosure (ditto). I've now moved on to TVCs which I find give a more lively/energetic sound (yet retain the detail) even though- in theory- I should not have had any roll-off problems with the stepped attenuator. I currently own a Promitheus, but am evaluating another make, because, unfortunately, they don't all sound the same!

As was said earlier, if your Wadia volume control works by reducing the digital signal, then using an external passive should sound better. (but you'll never know till you try it!)

Good luck

 

thats a great summary...........my two are an alps pot with relay switching and a stepped pot with a standard rotary selector...

they sound rather different ....alps being smooth and dark ...stepped clean clear desperately analytical...

 

excellent info parkand bike...thanks...what does tvc stand for?.

I bought the new PaulMccartney album yesterday......the album is good, but the sound production is woeful. Lots of compression.

I played it on the wadia, direct to the power amps and it was unlistenable really. Scratchy and like a strangled cat.....today I tried through my avi pre-amp...it sounded much better, but almost like the pre was making up / interpreting the sound itself..

is the difference that a passive is more faithful to the original recording and a pre amp adds "something" to the mix? I feel that the wadia does sound more engaging (though crappy on some tracks) and the addition of the pre makes it sound more like a radio station....enjoyable, but not really engaging????? Can pre amps still allow the music to be engaing and wonderful, or are they just to make the music "bounce" a little????
What is better if you like "music" and not "hifi"

 

just typed passive pre amp into ebay and found a very good section on NVA amplifiers by Richard Dunn....the info and ideaology sounds really good....anyone familiar with such gear?

 

If your budget is under £500 - I would try a promitheus Passive TVC. I could possibly help here if interested as I know where there is a cheap one (friend of mine who liked them so much he bought two) btw - also applies if anyone else on the lookout, friend is in London but will post - it's a single ended RAC version unused still boxed.


TVC = Trousers Very Crispy or sometimes known as Transformer Volume Control

 

No

you can't get anything back ...you only loose information from the source onward..the trick is to loose the least amount...

I suspect that the volume control of the wadia is affecting the end quality [though I didn't really notice it was having a great effect] ...the avi pre is passing the information relatively faithfully but adding its own "colour" or flavour to the sound. I can't comment on the disc as I've not heard it.

 

... or in a less than ideal world (which is where most of us live) if the source is "adding" something you don't want (and that could be the player or the recording itself), to lose what you want to lose and not what you don't.

 

errr let me read that again !

I was generalizing...

 

IMHO I have never heard a passive of either a resistive or transformer type that has not sounded broken in comparison to an active pre.
For your sort of money I'm a big fan of the Rega Cursa, it has lots of inputs, including phono, adjustable output level for easy matching to any power amplifier and full remote control.

 

what do you mean "broken?"

 

Not working properly

 

Come on!!

I've heard some passives that are wonderful and been very hard pushed to decide between a decent passive and an active costing thousands and thousands of pounds!

 

passives are difficult in some systems. they demand things put in order upstream, no impedance or sensitivity mismatches etc. they don't EQ the sound, at least not as much as actives do therefore being used to mask upstream friction between components.

althought i have just sold promitheus TVC i can fully recommend it as a great solution when funds are limited. at approx. $500 there is nothing to touch it.

it is not perfect but it is much better than many pricey preamps, including some that are considered to be benchmarks.

i haven't tried music first but promitheus is clearly better than bent 102 TVC based on S&B102 mk2 with seiden switch. clearly.

currently i left EAR 864 in my system because i enjoy its lush but not too warm midrange, better soundstage and PRAT, however i think promitheus has deeper bass and a bit more detail. but as i'm not in a forensic audio mode these days, i just prefer a bit more emotional approach EAR does when feeding my cold-blooded ATCs.

if seeking for absolute in TVC world, it is necessary to seek for a design with double-C core trannies if you want to have a fully correct timber and energy of the live instruments. EI cores, whatever is done and whatever material and tricks (as in S&B) are used, can't do it 100% correct - they will at best sound a bit too polite and pedestrian. once you hear a proper double-C TVC, no way back.

after my observations on this at several forums where promitheus was highly praised, nicholas chua (manufacturer) has now announced a super-charged version of it with C-core trannies. i don't mind about copyright issues, glad that someone is listening with open ears in this world of super high-end egos.

 

No really. I wouldn't lie to anyone who looked so cute

Tried stepped, ladder, shunted, and S&B TVC betwixt my cd and valve power amp. Shunted came out the best with the TVC sounding like I had slowed down the cdp. Then went to a WAD pre and there was just more detail and control. And I've similar in a few more places.

 

interesting, can you provide more details on the rest of your system?

also what shunted passive you've had?

 

At the time it was an Audionet cdp and WAD 6550 power amp into IPL S3MTL ribbon.

The shunt was DIY using an ALPS blue 100K log shunted with a pair of Riken 97K resistors wired with 0.5 solid silver wire.

 

Martha says thanks - she is cute - but sorry I really can't go with passive sound broken. Actives add stuff - but sometimes what they add is rather pleasant (new word for Zerogan there). As I have said before it really is a question of balance throughout the system. Me - valve powers and passive preamp sound wonderful, valve pre and and Krell - hmmmm . .. and Hi Gordan! - still on the trail eh?:JPS:

 

I have yet to hear ANY passive pre that did not have a detriment effect on the sound.
Simply no subsitute for a fully active pre. IMHO