which pre amp for SS amp and vintage La Scalas???

[tswei]

Any suggestions for a used Pre to use with my late 1970s Scalas?

I have a SS bel canto amp, and a Trends TA-10.2. I listen to all variety of music - mostly classical, rock, some jazz. Looking for some warmth but I don't want to lose too much detail/drive/etc.

Was thinking COnrad Johnson or Audio research used for $1-2K.

[tube fanatic]

I'm assuming that you're not looking for a phono stage. Since the Trends amp has its own volume control, why are you looking to pair it with a separate preamp? Is your Bel Canto an integrated, or power amp? If the former, again why add an outboard preamp? If the latter, I'd consider using a simple passive line stage. With most power amps needing around 1 volt of drive for full output, the passive line stage, fed by a cd player for example, will give you a level of clarity and soundstage width and depth which is difficult to attain with powered equipment. In addition, by eliminating a stage of amplification, there should be much less noise as well. Just the other day, in fact, I built a pair of mono passive attenuators for a guy who is driving his CWIIs with a Rogue Stereo 90. When compared with his powered Krell preamp, the difference in noise, graininess, and the sound itself was staggering. If you're handy, you can build the passive units for around $20 in parts from Radio Shack. The only recommendation is to use very short, low capacitance, interconnects between the passive unit and the amp.

Maynard

[tswei]

In the past with other systems, I have found that the pre-amp stage can make a BIG difference with sound. I get better soundstage, dynamics, everything really.

My BC is an integrated, the Trends is a pure power amp so it could use a pre-amp.

My idea is a tube pre so I can tube rolll to adjust the tone. The BC is pretty good, but the tone is a bit cold and there is some detail missing. I'll probably sell that unit to finance the pre-amp.

ANd yes, phono stage is not important, I figure I can add that later if I go in that direction.

[tube fanatic]

In the past with other systems, I have found that the pre-amp stage can make a BIG difference with sound. I get better soundstage, dynamics, everything really.

My BC is an integrated, the Trends is a pure power amp so it could use a pre-amp.

My idea is a tube pre so I can tube rolll to adjust the tone. The BC is pretty good, but the tone is a bit cold and there is some detail missing. I'll probably sell that unit to finance the pre-amp.

ANd yes, phono stage is not important, I figure I can add that later if I go in that direction.

Any component in the signal chain has the potential to influence the resultant sound. In choosing a preamp, try to find one which is set up as a dual mono design. When the channels share the same power supply rail, there can be a great deal of crosstalk (i.e. blending of the 2 channels) which can greatly influence the soundstage size and so on. Obviously, imo tubes are the way to go! Good luck with your search. I'm sure you will come up with something satisfying.

Maynard

[Daddy Dee]

tswei,

i'm thinking that you've already got some very good amplification for your LaScalas without putting a preamp ahead of them in the stream.

My take from listening with other gear, is that it is a peculiar characteristic of these chip amps that they are just not improved by putting something in front of them to flavor the sound. This does work with some poweramps which can be made to sound different with a different pre in the stream

I'd look at a couple of things. If your 70's lascalas have original crossovers, the old caps could be the cause of some harshness. Fresh caps can make an impressive difference. Don't have to break the bank either.

Other question would be about your source. a pretty important consideration that

[Islander]

I'd second what Daddy Dee said. A few months after I got my 1974 La Scalas, I replaced the old tin-can caps with new Sonicaps from Bob Crites and the sound was immediately more clear.

A day or two later, I replaced the original K-77 tweeters with a pair of CT125s, also from Bob. The original tweeters varied 2-3 dB between them, while the new ones were within 0.5 dB of each other. That improved the stereo imaging, plus their ability to play at much higher frequencies helped the sound of instruments like cymbals, as well as other high overtones.

I'd suggest you get your La Scalas performing at their best before tweaking other items in the signal path, since right now you're probably not hearing them as they should sound.

[tswei]

Yup, in the process of getting them up to spec right now (even re-finished the birch cabinets in a nice dark walnut!) and they look great. Put the drivers back in this morning and my re-capped AA crossovers from Mr. Crites should be arriving tomorrow sometime. Can't wait to get them back together as I know the caps will make a big impact as will fixing some damage to the cabinets that was causing some mid-bass resonance.

I guess I'll start out with what I have and look forward to a lifetime of rotating different upstream components into the mix. Even with all the problems with them when I first got them, I was awed with the scale, weight and dynamics of the sounds. A bit harsh on the high end with my SS stuff, so that's why I ask about tube pre-amps.

The more I read about the subject the more I want to get my hands on some Conrad Johnson stuff.

[Islander]

The midrange on the Scalas can be a bit "shouty". When I first got my La Scalas I was a little disappointed with the sound and resolved to do something about it. I experimented with adding grille cloth in front of the tweeters and squawkers. Even a single layer in front of the tweeters gave a veiled sound that was not as good as stock, but two layers in front of the K400 horn made the sound smoother. I settled on three layers of tightly stretched black grille cloth, stapled to the inside of the cabinet (after removing the horns, of course). That took away the harshness, without making the sound seem at all muffled.

If you have the mid-'70s models with the removable tops, it's easy to apply grille cloth to the inner side of the front panel, then re-install the horns and tops. It improved the looks of mine, because the insides of the mid horns had lumpy castings and blotchy paint. If you look closely at my avatar picture, you may be able to see the cloth covering the mid horn.

Another way to go is to change the tap on the autoformer. I don't remember the specifics, but one of them has two or three taps you can use. Switching from the standard position to one of the other ones will reduce the output of the squawker, which may make the sound more pleasant to your ears. I didn't bother with that, since I was satisfied with the addition of the grille cloth.

Once I'd done those minor tweaks, I was very happy with the sound of the La Scalas. A year later, I got a high-quality power amp, a Yamaha MX-D1, and that made a very noticeable improvement in the sound, in increased clarity and reduced distortion.

The next step came a year later, when I converted them to 510 JubScalas, but that's another story.

[tswei]

That "shoutiness" is some ways is what I like about the LaScalas, esp. for classical and for low-volume rock. For classical I am hearing the hall more than ever and minute nuance of how the string players are playing. Of course this translates to harshness in other forms of listening. I guess it's tradoffs.

Too bad no-one is making a pre-amp with different tube stages that can be optioned with a switch so that you can fine tune sound based on the recording or mood.

[Quiet_Hollow]

Too bad no-one is making a pre-amp with different tube stages that can be optioned with a switch so that you can fine tune sound based on the recording or mood.

Try inserting a high quality EQ unit, then shelve the top end by -2 dB or so. I think you might find the flexibility you're seeking in doing that. With a good unit, you can always throw the bypass switch when you want to go back to the stock sound.

[tswei]

I've heard that EQ creates phase problems, is that true?

And do you have any rec's on which unit?? Seems EQ was popular in consumer stuff in the 70s but has now disappeared.

[NOSValves]

In the past with other systems, I have found that the pre-amp stage can make a BIG difference with sound. I get better soundstage, dynamics, everything really. My BC is an integrated, the Trends is a pure power amp so it could use a pre-amp. My idea is a tube pre so I can tube rolll to adjust the tone. The BC is pretty good, but the tone is a bit cold and there is some detail missing. I'll probably sell that unit to finance the pre-amp. ANd yes, phono stage is not important, I figure I can add that later if I go in that direction.

Any component in the signal chain has the potential to influence the resultant sound. In choosing a preamp, try to find one which is set up as a dual mono design. When the channels share the same power supply rail, there can be a great deal of crosstalk (i.e. blending of the 2 channels) which can greatly influence the soundstage size and so on. Obviously, imo tubes are the way to go! Good luck with your search. I'm sure you will come up with something satisfying.

Maynard

I'd like to see a list of "true" dual mono tube preamplifiers and the specification that support your channel cross talk theory..

[tube fanatic]

I'd like to see a list of "true" dual mono tube preamplifiers and the specification that support your channel cross talk theory..

Gee, I thought you had actually mellowed a bit (silly me!!!!!) Crosstalk when power supply rails are shared is not a theory, it is fact. Get out your 'scope and signal generator and measure it yourself with a shared rail vs. 2 separate supplies if you need convincing. Email if you want to enter into a detailed discussion of design parameters. I won't waste forum space arguing with you. Sorry bud!

[Quiet_Hollow]

I've heard that EQ creates phase problems, is that true?

It can be, if used incorrectly. But what's also rarely ever spoken of is that EQ can also alleviate some nagging issues.

Besides, more often than not, the room and speakers are having their way with the system phase response much more so than any upstream electronic gear.

And do you have any rec's on which unit??

Is your signal path analog or digital? Once the forum knows that, then we can advise from there.

Seems EQ was popular in consumer stuff in the 70s but has now disappeared.

On the contrary, EQ is alive and well. The biggest issue is electronic devices that are being shipped with predefined EQ profiles that are not customizable or defeat-able, which often leads to bad sound.

[tswei]

My source is digital Apple Lossless> SONOS>PS Audio Dac

I hope to get a turntable someday and re-purchase my top 20 albums in the best vinyl I can find.

[NOSValves]

I'd like to see a list of "true" dual mono tube preamplifiers and the specification that support your channel cross talk theory..

Gee, I thought you had actually mellowed a bit (silly me!!!!!)

Not when it comes to you! So your not going to answer my question... measurable maybe audible......NO

[derrickdj1]

It sounds like the use of exotic speaker wire. I think I can hear a difference from here(pparently the idea of dual mono preamplifiers is still popular).

[NOSValves]

In choosing a preamp, try to find one which is set up as a dual mono design. When the channels share the same power supply rail, there can be a great deal of crosstalk (i.e. blending of the 2 channels) which can greatly influence the soundstage size and so on.

Tube Fanatic,

Mark Levinson has made several "dual mono" preamps. So has Mark Deneen. I designed the B-100 dual mono preamp in 1979 for ADC. It was an all out assault on the crosstalk issue. It included two power transformers, four regulated power supplies, 14 tubes and separate amplifiers for the MM and LOMC inputs. It sounded pretty darn good. Not too many were made - something like 100 units before ADC was shuttered by BSR. But the design did specifically exist to address the question of common power supply distortion and isolation.We had just purchased one of the first commercial spectrum analysers - for $55.000! And of course, we went to work justifying the expense! Well, you get the idea.

As a philosophical concept in the field, if dual mono makes sense for a power amplifier it makes sense for a pre-amplifier - for exactly the same reasons. In short, the relationships of current, voltage and phase are always relative. If it is problematic at high numbers it is problematic at low numbers too! Any argument over what is audible and what is not is meaningless without full disclosure of the entire system of gear, room and media and system of evaluation. Then the argument always proceeds to relavance - does any one care about the difference? Well, some do and most don't. Old story, nothing new. It was that way in 1979 when I wanted to put two $40 transformers in one chassis, and it is that way today when someone wants to use a $50 capacitor somewhere.

I haven't been keeping up with high-end audio, so I don't know who is doing what these days. But for sure, "dual mono" was a well-understood goal back in the Golden Age.

Well Mark if it sounds so good, test so good and made such a remarkable difference why was it not employed in the Juicy Music products? I say much to do about nothing..... same can be said about the difference in mono block amplifiers, true dual mono stereo and shared power supply stereo amplifiers. Sure you can measure the difference but hear it no way. The truth is the real world audible difference is minuscule at best.

[NOSValves]

Mark,

What are things getting slow in your normal political argument hang spot out these days? I suggest you remember you are not in a special section where you can get away with this garbage.

[NOSValves]

Mark no the subject was not dual mono preamplifiers... read the initial post. You really can be one childish baby.