preamps

[MooseTrackz]

As a condition to a recent sale I agreed to do a review of preamps in general, so here goes:

My first venture into audio was in the early 70's in a place a long way from here. Me and my best friend Elvis wandered into Hertzogs Store and checked out their "stereo's", if the mind isn't playing tricks it was a very impressive Marantz setup for about $800.00 which was probably a good price. Except if you were making $0.75/hr we were looking at light years to pay for it! (in those days credit was for the rich and famous, and we were neither rich nor famous) We still strung the sales guy along for a while and the full extent of his/the shop's record collection, deciding along the way a number of albums not to buy (ever). Years later, 3 to be exact I purchased a Rotel receiver and a Dual turntable along with a Massive pair of Avanti speakers and a Hitachi tape deck which reminded me of the wall of sound that Pink Floyd erected in Hamilton around the same time (well in my head forever always). A few years later I got a real job that paid $$ and upgraded my sound system as they were now called (sold the old one to my brother, hehehehehhe) to a Denon integrated amplifier + a Dual turntable + a Dual double tape deck + Angstrom speakers (which I still have), whoowee I was heading for audio bliss. I made the fatal mistake of reading Stereophile and realised that my simple little system was a mere blip on the edge of audio heaven. So I scrimped and saved and other stuff and bought me a power amp which I stuck into the system and in my ears it reined supreme for many many years,

I've been lurking in the background since this was the cloney forum thingie, reading all of your adventures into modern sound systems and thinking...that sounds interesting, I wonder how that really sounds etc. I've had an itch that needed scratching about valves, so recently I purchased a Valve preamp.

I've had a SS Preamp (Krell) that works exceptionally well, it is so neutral you wouldn't know it was in the path at all. But it has a small volume issue, in that its very hard to go softly softly. Its either rock your socks off or mute, I prefer the rock your socks...but there are others to consider(or so I'm told).

So I got this valve preamp and loved it (it sorted the volume issue and still allowed the sock your rocks off)

The valve preamp adds a warmth/fullness to the sound that to my mind enhances the overall soundstage and makes it all full on.
Which now makes me wonder about the hybrids, most possibly the best of both worlds or not.....the adventure continues, oh yeah,

[Adrian]

Good on ya man, now what you must have a taste of is either a Leben preamp or Jadis preamp. Purely just for experimental purposes of course!!





When the wife asks WTF is going on? You can explain that they are just 'resting in my system'!!

[Fran]

A great read!!


Its hard to beat a good valve preamp I think. Same thing for phono stages...... I would have thought there was a gain adjustment possible in the Krell though - it might be worth hunting around on the web a bit for a service manual if its an older model, or contact Krell to ask them if its newer.....


fran

[Audioq]

Rotel & Dual with little Kef standmounts, ah yes! Those were the days. Did you buy them from Lafayette on the keys beside the Virgin megastore. Fond memories.

[MooseTrackz]

I would have thought there was a gain adjustment possible in the Krell though -

fran

I actually have the manual and yes there is a switch for the gain but even with it in it's lowest setting the gain range adjustment is tiny (a couple of mils on the volume knobby).

I guess its just one of those annoying traits that one has to get used to.

The valve pre is the exact opposite and requires a serious amount of crank to get the volume well up. Unfortunately the left channel has given up the ghost so I will need to get that fixed.

Any suggestions??

[Fran]

On the volume side - it seems like a case of a fairly high gain preamp with a fairly high gain power amp.... giving you a tiny adjustment range. I know Fergus of this parish had a similar issue with his Jadis and he got a couple of sets of rothwell attenuators and they did the trick. Reading around some seem to think they rob some of the dynamics, but I don't think Fergus experienced this.

RE the channel being out - valves use high voltages that can kill, so I wouldn't go poking around in there unless you know what you're doing (SS amps/preamps rarely go more than 60 or 70 voltages, enough to give you a trickle but not kill ... usually). Cloneys can probably put you in contact with someone they use for valve work.... might be tiny, or might be more, impossible to say without a good look under the bonnet.

What is the make/model of the pre?

[Ivor]

RE the channel being out - valves use high voltages that can kill, so I wouldn't go poking around in there unless you know what you're doing (SS amps/preamps rarely go more than 60 or 70 voltages, enough to give you a trickle but not kill ... usually). Cloneys can probably put you in contact with someone they use for valve work.... might be tiny, or might be more, impossible to say without a good look under the bonnet.

What is the make/model of the pre?

it's my old Audio Innovations p200 Fran which you had a good oul' poke around yerself! I'd try swapping the two obvious valves (I think the third one to the left is for the phono stage) and check fuses if they're are any on the L R outputs (I forget). It's a very simple circuit and very little goes wrong with them.

[Fran]

Does that haver a stepped volume pot?

[Ivor]

Does that haver a stepped volume pot?

No, standard issue. (as far as I know!)

[fergus]

On the volume side - it seems like a case of a fairly high gain preamp with a fairly high gain power amp.... giving you a tiny adjustment range. I know Fergus of this parish had a similar issue with his Jadis and he got a couple of sets of rothwell attenuators and they did the trick. Reading around some seem to think they rob some of the dynamics, but I don't think Fergus experienced this....

That is very true Fran; the attenuators worked for me. My preamp has massive gain with a miniscule adjustment range on the volume knob. The attenuators just gave me more flexibility with the volume adjustment without any noticeable loss in the dynamics; however I must stress that the gain was massive and I was unable to really let the system rip in a domestic situation so a real comparison was never done. The function of the attenuators was merely volume control for me.