[Jimmy71]

Any suggestions or experience with tube preamps and Bryston power amplifier?

[CanadianMaestro]

You miss this thread?

http://www.audiocircle.com/index.php?topic=155337.20#msg1666046

cheers

[TJ-Sully]

Hi folks

I have upgraded my beloved 4BSST2 for a 4B3. I have a BP20 preamp.

I am getting some Maggies, and I am interested in getting a tube preamp as well - to compare the listening experience .  (never had tubes before).

This notion has got me thinking about impedance loads.

The input impedance of the 4B3 is reported to be 20K ohms (balanced) and 29K ohms (unbalanced).

Any thoughts out there on suggested output impedance for a tube preamp into a solid state amp with these specs, or similar ? 

I've read 10:1 or even up to 100:1 ratio's are the golden rule.

Thoughts appreciated!!

TJ

[CanadianMaestro]

I find 25:1 to work quite well. No higher than 40-50:1 
With my LS27/14B-squared combo, it's at 30:1 (all balanced).

 

[Rusty Jefferson]

Don't get too caught up in the impedance matching.  It's important that your preamp be able to easily drive your amplifier, but most of the preamps you're likely to be looking at should work fine with your amplifier 30k ohm input impedance. 

On your other thread asking for preamp recomendations, someone mentioned the Microzotl preamp from Linear Tube Audio.  If you're concerned about low output impedance, I don't think you'll find a tube preamp with lower output impedance, about 2 ohms.  That thing can drive any load you can feed it. Long interconnects and/or multiple amplifiers, and with great dynamics. https://www.lineartubeaudio.com/products/microzotl-preamplifier

The one I mentioned in the other thread with the interchangeable circuit boards has output impedance between a few hundred ohms and 2-3k ohms depending on how you configure it.  No problem driving that amplifier with normal length interconnects.
http://www.musicaldesign.com/MC_Cham.html

[TJ-Sully]

Thanks Rusty. I checked out those links on the Tube-o-phile thread a few days ago. They are nice looking pre-amps and excellent examples of preamps with low output impedance. Down to 2 ohms is unreal. 

But interested in perspectives on using various impedance loads and observations - of why impedance loads are important to match, or not so much....as some suggest.

T

[Rusty Jefferson]

Again, in normal circumstances you are unlikely to have a problem with or hear a difference between 2 identical tube preamps,  one with 1.5k ohms output impedance, and the other with 3k ohms output impedance, using your amp with 30k input impedance,  if you're not running long interconnects (unbalanced) and or biamping, even though you've halved the ratio with the 3k ohm preamp.

I had a problem with my system once when biamping 2-22k ohm input impedance SS amps from a preamp with 3k ohms output impedance unbalanced.  The biamping also added extra cables. There was definitely a loss of dynamics and drive to the system.  When the ratio gets that low, 3-4:1 you're going to hear it. Ultimately, I solved the problem with the Microzotl. Same low output impedance like a SS preamp, but with tubes.

[rodge827]

Here's a very good preamp at TMR:

https://tmraudio.com/components/preamplifiers/supratek-chardonnay-stereo-tube-preamplifier/

I have dealt with TMR in the past with very positive results.

Chris

[CanadianMaestro]

But interested in perspectives on using various impedance loads and observations - of why impedance loads are important to match, or not so much....as some suggest.

T

Google it. Here -

https://www.google.com/search?q=why+amplifier+impedance+is+important&ie=utf-8&oe=utf-8&client=firefox-b

[TJ-Sully]

Google it. Here -

https://www.google.com/search?q=why+amplifier+impedance+is+important&ie=utf-8&oe=utf-8&client=firefox-b

aww...thanks CM, for the tip on how to use Google.   Yes, i needed that.

[TJ-Sully]

Again, in normal circumstances you are unlikely to have a problem with or hear a difference between 2 identical tube preamps,  one with 1.5k ohms output impedance, and the other with 3k ohms output impedance, using your amp with 30k input impedance,  if you're not running long interconnects (unbalanced) and or biamping, even though you've halved the ratio with the 3k ohm preamp.

I had a problem with my system once when biamping 2-22k ohm input impedance SS amps from a preamp with 3k ohms output impedance unbalanced.  The biamping also added extra cables. There was definitely a loss of dynamics and drive to the system.  When the ratio gets that low, 3-4:1 you're going to hear it. Ultimately, I solved the problem with the Microzotl. Same low output impedance like a SS preamp, but with tubes.

Rusty, thanks man. this is exactly the kind of informed perspective I was hoping for in helping me to understand the implications if impedance matching, and possibly not getting it right. And also helps me perhaps, not to fret about impedance loads approaching 10K into a SS power amp at 30K input impedance.

I understand that poorly matched impedance can affect the functionality of cables due to impacts of amount of voltage - in addition to affecting the shape of the frequency response (flatness, especially at lower frequencies).

I think i'm starting to understand.

Thanks again for thoughtful responses.

TJ

[CanadianMaestro]

aww...thanks CM, for the tip on how to use Google.   Yes, i needed that.

aww....I'm so moved....

[TJ-Sully]

Here's a very good preamp at TMR:

https://tmraudio.com/components/preamplifiers/supratek-chardonnay-stereo-tube-preamplifier/

I have dealt with TMR in the past with very positive results.

Chris

Thanks Rodge827! That is one cool looking unit. I'll will do some reading tonight on TMR. Cool!!

[adol290]

I had a manley 300b preamp. I was using it with the 7bsst2.
 Really liked how both sounded together.

Not sure if it's in your price range.

https://www.manley.com/hifi/neo3br

[CanadianMaestro]

I had a manley 300b preamp. I was using it with the 7bsst2.
 Really liked how both sounded together.

Not sure if it's in your price range.

https://www.manley.com/hifi/neo3br

Looks nice.
But at that price ($9K), one should expect balanced in/outs.

cheers

[TJ-Sully]

I had a manley 300b preamp. I was using it with the 7bsst2.
 Really liked how both sounded together.

Not sure if it's in your price range.

https://www.manley.com/hifi/neo3br

beautiful looking pre-amp.  I bet it sounds lovely.
there's one on Audiogon - looks mint at $3400USD or so.
a little out of my range..but thanks!!
TJ

[Markwatkiss]

Audio Research tube pre amps continue to be a seamless match with Bryston power.

[CanadianMaestro]

Audio Research tube pre amps continue to be a seamless match with Bryston power.

Sure are. I also like the very sensible way the input/output jacks are arranged at rear panel (of LS27 and others). Top-bottom, rather than left-right. XLR outs both on the far right rather than separated at L and R edges of panel.