Active versus passive

[Gordon Steadman]

Not the usual arguments about which is best but a technical query.

As the Stereo 20 is hors de combat, I am using the Quad303 to drive the 57s. I had a couple of hours free from demolition work on the house today so had a wee play.

My usual pre is a Creek passive but I have a Quad 33 and a Sugden - C51 I think - that I have used with the 303 so I thought I'd do a bit of swapping and see which I preferred.

The Creek drives the Quads to reasonable levels but not head banging stuff. I expected both of the active pre-amps to give more volume but in fact, both gave quite a bit less, very similar levels in fact. To listen at a reasonable level, I had the volume on both at maximum.

Why is this I wonder? I assumed that there would be higher output levels, otherwise, what is the point of an active pre with all the extra gubbins in the circuit?

I still prefer the sound of the Creek with the other two pretty even with the Sugden having slightly better clarity but the 33 having better bass. Neither were pipe and slippers

[Barry]

What is the source and to which preamp input is it connected?

[Gordon Steadman]

What is the source and to which preamp input is it connected?

I tried it with both CD and disc. Disc direct into the pre was too quiet to listen to but when through a Firebottle phono stage, it was at the same level as the CD, All connected direct to each pre in turn.

[Simon_LDT]

There must be an impedance mismatch somewhere if you're having levels set to max and it's not blowing your head off with sound.

[Gordon Steadman]

There must be an impedance mismatch somewhere if you're having levels set to max and it's not blowing your head off with sound.

Indeed but then the 33 and 303 were designed to go together which is why I find it more than a bit strange. I'll try the other 303 just in case it's the amp.

It's not important as the Creek is fine but I would like to know as it may well be that I will want to use one of the pre-amps in a system at some time. They are all part of my back up plans, the 57s are amp fussy.

[DSJR]

The 303 should work just fine with a passive preamp and sound better too. Mine actually has its input gain reduced slightly (from an estimated 500mV to 750mV) and it's fine and being used right now with an NVA P50. The law of the volume control itself is important and 'we've' been duped into thinking that nine o'clock on the volume control is a fine place to have a loud volume with a CD level source. In reality, this means we have no proper control over very low volumes and of course, less expensive volume pots (even Alps ones) will mismatch channels at the bottom of their rotation scales.

The 57's work just fine with a 303, BUT, this is where the 33 preamp comes into it. The 33 response was deliberately (it seems) hobbled to better match the 67's load as driven by the 303 (the 303/57 sub bass performance is a disaster, so Quad engineered a vicious roll-off in the 33 bass response below 35Hz in an attempt to deal with it - this is in the days of noisy rumbly turntables as a prime source remember). There is an HFN article about this somewhere, with measurements as proof, but I can't currently find it.

If you feel the need for a bang up to date preamp with some gain to it, please consider a Croft Micro 25, as there's more than enough there in the line stage and it particularly works well with the 303 I found, as well as other power amps. It's insertion loss is minimal and it can be tweaked with different valves and so on 'to taste.'

[Macca]

33 and 303 and ESL speakers were designed to work together so if you need to whack the volume to maximum to get decent levels something is broken somewhere. It is that simple.

[RothwellAudio]

The Creek drives the Quads to reasonable levels but not head banging stuff. I expected both of the active pre-amps to give more volume but in fact, both gave quite a bit less, very similar levels in fact. To listen at a reasonable level, I had the volume on both at maximum.
Why is this I wonder?

Yes, that does suggest something isn't right. The specs for the 33 say the gain of the radio input is 14dB. The Sugden has 12dB gain (I think), so both should be noticeably louder than the passive. Things need checking out.

[Gordon Steadman]

I've now swapped 303s.

It's exactly the same as far as level is concerned but I just about prefer this one for some reason, who knows why?

I am left with the fact that both active pre-amps behave in the same way. It's not something I will lose sleep over as the Creek is staying in place but it is all rather strange.

I may try them with the 306 to see if they are any different.