2. amps-preamps
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Importance of line stage pre--Who Knew?

Well, I'm sure a lot of you knew, or there would be no $5K and up market for line stages.

As for me... This month marks the 40th anniversary of buying my first stereo with my own money. In all that time I've only had solid state in the signal chain except for a Jolida phono preamp and matching line stage I picked up a couple of years ago. It turns out that the tubes in those units were for a buffer stage to warm up the sound, while the gain was handled by op amps. Well, recently an audio buddy came by to spin some vinyl and show me a tube-driven line stage preamp he wanted to sell.

See it here.

This is just a simple, modest line stage preamp with 5-input rotary selection knob, balance, and volume. Five pairs of inputs, one fixed and two volume-controlled pairs of outputs on the back. However, it's a PTP hand-wired design with tube rectifier and large transformer. I didn't want to like it as it had a couple of deal-killers: 1) no remote control and 2) too tall to fit on my audio rack thanks to that outsize transformer. It would have to be a game-changer for me to consider getting it.

We tried it out in the humblest of circumstances. I set it on a Rubbermaid step stool in front of my rack and patched it into the signal path, bypassing the Jolida op amp/tube buffer line stage.

HOLY MOLY!

Game changer? Sh'yeah! After just a few seconds of hearing it you know it's not leaving the house. So what did it do?

It simply sounded more real and less electronic. It heightened the illusion of performers in real space making music. It took my system a big step away from a tune player to a sonic virtual reality device. Sonically the difference might be considered subtle, but in the realm of emotional response to the music, it was a big step. There was more separation between the various elements of the mix, and if you sat in the sweet spot between the speakers, you heard a 3-dimensional image of performers spread out before you. That physical separation also separates into audible separation. It was easier to hear how the musicians interact with each other to make music together--just like in a live performance. Instead of an amorphous left-to-right smear there was a sonic hologram of where the performers stood in the mix. However, this did not desconstruct the performance, but rather showed how the elements worked together to form ensemble music.

Timbres sounded more real: Brass had more blat when called for, more sense of air flowing through metal, of lungs full of air providing the energy for the resulting sound. Strings sounded pluckier, voices more human, acoustic instruments woodier... you get the picture. It made LPs sound enveloping with a nicely laid-out soundstage, and it elevated computer-based digital music from tolerable to involving and enjoyable, again with the 3-D imaging and wider-than-the-speakers sound stage.

Before picking up this piece, I was thinking of upgrading amplifiers yet another time. But I experienced a valuable lesson I had previously known more in theory--that for fine gradations of amplitude, tubes rule, and it's the low level--preamp and component level--signals that are most fragile; if part of the signal drops out at that stage, no amplifier will bring it back regardless of the amp's bandwidth, rise time, signal-to-noise ratio, or resolving power. The preamp has to caress and amplify those low level signals and pass them on to the amplifier so you can groove to them when they exit the speakers. Since all my sources--LP, CD, FM, iPod, and computer--run through this unit, everything sounds better,

In fact, one of the things I learned from this experience is that my $220 used 1981 Heathkit amplifier is even better than I thought. Paired with this preamp, it is still superb. Sure there are better and much better. But for now and some time to come, it'll do nicely.

Since picking it up I swapped in a set of Sylvania NOS tubes--a JAN (mil-spec) 6X5WGT rectifier (smoother delivery and better voltage regulation) and a matched set of '50s-era Sylvania 6SN7GTB triodes (even more liquidity, less grain, more 3-D imaging). I'm a happy man. Next up--sell off some electronics and get a tube phono stage from this maker.
johnnyb53
plato
1,543 posts
 
Okay, ClioO9, You're right, we are not going to agree. But I want to make a couple of points. First, yes, perhaps direct-coupled OTL amps are a little less muddled than other types (I have owned the Atma-sphere M60 Mk3.1's btw as well as highly-modified AHT/Acoustat direct-drive OTL amps), but conventional OTL's like the Atma-sphere's throw an amazing amount of heat which is not great in AZ in the Summer. But beyond that, they are a crap-shoot as far as their bass-performance goes because of the usual bass impedance peak at some audible low frequency. I had a problem with that.

Second, my idea of using chassis diffusing feet on my gear applies equally (if not more) to tube gear, not just digital and solid-state. I take it from your remarks about power regeneration that you are poo-pooing it, which I find very suspect in view of the sonic improvements regeneration provides. But I won't argue further with you because I see no point in it due to your close-minded attitude.

Charles1dad, you're right, I don't know the full scope of your experience but without me tooting my own horn I would just say that the odds are (being a past president of the NJ Audio Society, a veteran Senior Reviewer and 40-year audiophile) that I have more experience tweaking different types of products and systems than you do. Without a resume of your experience I haven't a clue.

I'll also allow that you and others may take the "tubes are great" view, and I basically agree, I just think there are other approaches that can equal or exceed the limits of tube technology based on my own first-hand experience (not other's opinions or hearsay). Sorry to be a progressive thinker, I guess.
clio09
3,354 posts
 
Plato, not necessarily poo-pooing power regeneration (I tried these products in my system so I do not consider myself close minded on the subject) but just your comment and the idea that this, along with cabling and chassis diffusion, is what is required to get the most from solid state. If you need all that then IMO something is wrong elsewhere in the system.

As for the Atma-Sphere your point on the heat and AZ is well taken. However I live in Las Vegas and have managed to tolerate the situation. In may case I look at it as an opportunity to have a built in sauna. Martini and iPad in hand, some good music, and sweat off a couple pounds in the process :)
johnnyb53 OP
3,510 posts
 

11-04-12: Stringreen
...a bit of a caveat......most changes (subtle, grand, good, bad) are perceived as a "Wow". Live with this new one for a few weeks and discover ITS warts...you just might want to go back to your old one.
This ain't my first rodeo. I bought my first stereo 40 years ago. I worked in high end audio retail for a year soon after. I've had a lifetime of swapping and comparing components, cables, and now tubes. I *know* what to listen for regarding long term musical involvement and emotional satisfaction.

There's no way the Jolida JD5T 10dB gain line stage can touch this MAGI PTP-wired line stage. I also have 15 years experience swapping current production Russian, Czech, and Chinese tubes against NOS GE, Philips, RCA, Raytheon, and Sylvania tubes, some JAN versions and some not. The NOS tubes--even up to '80s production Philips JAN 12AX7WAs--are consistently quieter, smoother, and more durable.

To those who wondered, my current setup is a Technics SL1210 M5G (has the factory tonearm rewire) w/KAB fluid damper, an Oracle sorbothane mat, tonearm wrap, LpGear ZuPreme headshell, Audio Technica AT150MLX. The turntable is platformed on a combination of brass cones, Vibrapod cones and pucks, a very heavy 3-1/2" thick maple butcher block cutting board supported by silicone gel pads. This feeds a Jolida JD9A phono stage with NOS Sylvania 5751 Gold tubes with Herbies tube dampers, with the unit sitting on Vibrapods. This formerly fed a Jolida JD5T line stage but is now feeding a MAGI all tube line stage to an unbelievable 1981 Heathkit AA-1600 power amp (about 180 wpc) powering a pair of Mirage OMD-15 floorstanders assisted by a pair of Mirage MM8 subs.
zd542
5,339 posts
 
This a really good thread. I hope a lot of people take the time to read it. A good preamp makes a huge difference. Unfortunately, most people overlook the preamp and go for the more "exciting" components like amps and speakers. Thats a huge mistake. When you get the right preamp, its like a window opens up in your system.
geoffkait's avatar
geoffkait
23,365 posts
 
There are simply too many variables to be able to make definitive generalizations about tubes and solid state or analog and digital. No doubt a lot of it has to do with implementation, cabling, vibration isolation and other tweaks, especially those addressing room acoustics. And whether CDs are just off the shelf and untreated, for example.
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