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 Post subject: preamp for pass xa30.5
PostPosted: Tue Jan 09, 2018 12:25 am 
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i thought i might ask this here. i tried checking audiogon threads but a lot of them have suggestions for gear listed on audiogon from 5 years ago and I did attempt to look up suggestions but had no luck in findin... anybody here want to point me towards some currently listed preamps on market already? thanks :)

tube or ss, don't really care, as long as it keeps my sound realistic and easy on the ears. budget $2-4k


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PostPosted: Tue Jan 09, 2018 1:12 am 
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Location: Hamilton, ON, CA
iriszizka wrote:
i thought i might ask this here. i tried checking audiogon threads but a lot of them have suggestions for gear listed on audiogon from 5 years ago and I did attempt to look up suggestions but had no luck in findin... anybody here want to point me towards some currently listed preamps on market already? thanks :)

tube or ss, don't really care, as long as it keeps my sound realistic and easy on the ears. budget $2-4k


You seriously Lucked-out here (hear) !

Consider the brilliant Cambridge Audio 840-E (preamplfier, circa 2008?-2014?).
The current Cambridge 851-E uses afar less sophisticated volume attenuation than the 840E's resistor/relay circuit. Used prices hover around the $900. mark.

A shockingly over-looked preamp that competes in the league of ML 326s territory; it is seriously that good/excellent.

pj
(P.S. It's being mated to a Classe CA-2100 power amp)


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PostPosted: Tue Jan 09, 2018 3:25 am 
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Do yourself a favour and investigate passive (zero gain) preamps.

My amp is similar to yours - a Nelson Pass designed First Watt F5 with 25wpc. Speakers are ML Source electrostatics which are 90 dB efficient. Your amp, with 11 dB more gain than the F5, should work well with even less efficient speakers. I'd been using a Meitner PA 6i for a couple of years. It's an excellent sounding preamp, but I felt I could still do better. First I bought an inexpensive used passive ($100), to make sure that zero gain would work in my system. It did, and at normal listening levels the volume control was at 50 to 75% of wide open. Then I got a Tortuga Audio passive pre, and in my system and in my room, it's been a very good step up in sound quality from the Meitner. And the features controlled by the remote control make it the the most convenient preamp I've had. I'm not suggesting that the Tortuga is the answer for you - there are several types of passives so learn about them and you may decide on a different brand. You will have sound that is realistic and easy on the ears. IMHO, I now have exactly that, to the highest degree.


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PostPosted: Tue Jan 09, 2018 7:32 am 
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Lutherton wrote:
Do yourself a favour and investigate passive (zero gain) preamps.

My amp is similar to yours - a Nelson Pass designed First Watt F5 with 25wpc. Speakers are ML Source electrostatics which are 90 dB efficient. Your amp, with 11 dB more gain than the F5, should work well with even less efficient speakers. I'd been using a Meitner PA 6i for a couple of years. It's an excellent sounding preamp, but I felt I could still do better. First I bought an inexpensive used passive ($100), to make sure that zero gain would work in my system. It did, and at normal listening levels the volume control was at 50 to 75% of wide open. Then I got a Tortuga Audio passive pre, and in my system and in my room, it's been a very good step up in sound quality from the Meitner. And the features controlled by the remote control make it the the most convenient preamp I've had. I'm not suggesting that the Tortuga is the answer for you - there are several types of passives so learn about them and you may decide on a different brand. You will have sound that is realistic and easy on the ears. IMHO, I now have exactly that, to the highest degree.



Passive line-stage ? No favors given with such a rec. Tell me, how is the volume attenuation accomplished in your passive device ?

pj


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PostPosted: Tue Jan 09, 2018 7:53 am 
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Location: Calgary, AB, CA
Have the same amp, what speakers do you have?

With respect to the preamp, finding a tube pre that has a low enough output impedance is tricky. Synergy between Pass preamps is readily available, though I have no experience with them. I use a PrimaLuna Dialogue Premium preamp and really enjoy it. I wish it had balanced inputs/outputs but that's just been finicky. Another option I've considered is getting a custom build from Don Sachs and he can build it specifically for the XA30.5. I've spent a good amount in tubes on my PL so I'm not super eager to start over but the 6SN7 tube is much different than the 12AU7 (or so I'm told I should say).

EAR 868 is another one I've had my eyes on but their stuff is usually beyond my budget and no one sells them locally.


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PostPosted: Tue Jan 09, 2018 8:18 am 
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Line or Line and Phono. How many inputs do you need. Do you require a remote.....

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PostPosted: Tue Jan 09, 2018 8:24 am 
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msommers wrote:
Have the same amp, what speakers do you have?

With respect to the preamp, finding a tube pre that has a low enough output impedance is tricky. Synergy between Pass preamps is readily available, though I have no experience with them. I use a PrimaLuna Dialogue Premium preamp and really enjoy it. I wish it had balanced inputs/outputs but that's just been finicky. Another option I've considered is getting a custom build from Don Sachs and he can build it specifically for the XA30.5. I've spent a good amount in tubes on my PL so I'm not super eager to start over but the 6SN7 tube is much different than the 12AU7 (or so I'm told I should say).

EAR 868 is another one I've had my eyes on but their stuff is usually beyond my budget and no one sells them locally.


Are you sure about the following:

[i]" ....finding a tube pre has a low enough output impedance is tricky." ?

NOTE: My mistake -you would be right -regarding low output impedance tube pre.

pj


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PostPosted: Tue Jan 09, 2018 9:09 am 
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Location: Calgary, AB, CA
No worries!

It's not easy finding a tube pre that can stay below 2000 ohms across the whole frequency (input impedance on XA30.5 SE is 20K, 30K for balanced). Truthfully, I don't even know if my PL can stay below that across the whole band but it's posted output impedance (256 ohms) suggests it's at least pretty close to maintaining that 1:10, ideally 1:20 ratio.


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PostPosted: Tue Jan 09, 2018 9:38 am 
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Location: Toronto, ON, CA
If gain is not required from the linestage then along with the passives
already mentioned, I would add the FirstWatt B1 (basically volume
control plus a buffer). You can even build one yourself if so inclined.


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PostPosted: Tue Jan 09, 2018 9:53 am 
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allhifi wrote:

Passive line-stage ? No favors given with such a rec. Tell me, how is the volume attenuation accomplished in your passive device ?


Volume attenuation is done with opto-couplers (LDRs), as is input selection - there are no pots, stepped attenuators, etc. or switches or relays of any kind in the signal path. See the Tortuga Audio website for a good explanation. A couple of years ago, I would have made the same comment as you. But now, after using a cheap passive (by Eric Yam in Hong Kong), then a Creek passive with remote (that I still use in a second system), and now the Tortuga Audio, I have come to realize that, for my ears, in my room, and with my amp and speakers, a passive preamp is the answer. And I feel that the opto-coupler is apt to have the least effect on sound quality.


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PostPosted: Tue Jan 09, 2018 10:32 am 
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I would suggest focusing on preamps that best match your specific amplifier, rather than what other CAM Members may have liked in their own (very different) systems.

I think you'll find that Pass recommends using a fully balanced preamplifier with amplifiers such as yours, due to the super-symmetry circuit design. Other Nelson Pass designs such as the First Watt amplifiers will have completely different preamp requirements.

Note that many preamplifiers have XLR inputs and outputs, but are not in fact fully balanced circuits, so some investigation is required when making your short list.


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PostPosted: Tue Jan 09, 2018 11:36 am 
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Here's a fully balanced Allnic L-1500 for $3K that's worth considering: http://www.canuckaudiomart.com/details/649316346-allnic-l1500/

As for impedance, I don't think you have to worry too much about that. Here's a quote from Nelson Pass regarding his amps:

"The amp doesn't care about source impedance. It's actual input impedance is close to 0 ohms, and the input impedance spec comes from the resistors we put in series with that input. Adding a little more from the source doesn't create issues."

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PostPosted: Tue Jan 09, 2018 12:37 pm 
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I can’t imagine why any of the Pass pre’s are not being mentioned here. Try an X10 or X20 for example?

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PostPosted: Tue Jan 09, 2018 1:29 pm 
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Lutherton wrote:
allhifi wrote:

Passive line-stage ? No favors given with such a rec. Tell me, how is the volume attenuation accomplished in your passive device ?


Volume attenuation is done with opto-couplers (LDRs), as is input selection - there are no pots, stepped attenuators, etc. or switches or relays of any kind in the signal path. See the Tortuga Audio website for a good explanation. A couple of years ago, I would have made the same comment as you. But now, after using a cheap passive (by Eric Yam in Hong Kong), then a Creek passive with remote (that I still use in a second system), and now the Tortuga Audio, I have come to realize that, for my ears, in my room, and with my amp and speakers, a passive preamp is the answer. And I feel that the opto-coupler is apt to have the least effect on sound quality.


Hi Lutherton: A man with some experience !

For sure, it's a matter of "coupling/synergy-zing" the right components. As you clearly are aware, volume attenuation must be given some serious consideration as it impacts performance to a significant degree; circuit bandwidth, channel balance, noise. All must be precise through its range of operation. It seems the opto-coup's is a capable method.

Yet, in a nutshell, the active line-stage (preamp) simply can be seen as a buffer (with gain); a high-input impedance, low output impedance.

This is not often the case (or the case at all) with most passive devices -particularly those using less than optimal volume attenuation. Hence, my recommendation of the Cambridge 840E; at $900. CA$ (used), good luck finding anything remotely close to its amazing performance (and excellent resistor/relay vol. attenuation).

Happy New Year to you,

peter


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PostPosted: Tue Jan 23, 2018 7:17 am 
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allhifi wrote:
For sure, it's a matter of "coupling/synergy-zing" the right components. As you clearly are aware, volume attenuation must be given some serious consideration as it impacts performance to a significant degree; circuit bandwidth, channel balance, noise. All must be precise through its range of operation. It seems the opto-coup's is a capable method.

Yet, in a nutshell, the active line-stage (preamp) simply can be seen as a buffer (with gain); a high-input impedance, low output impedance.

This is not often the case (or the case at all) with most passive devices -particularly those using less than optimal volume attenuation. Hence, my recommendation of the Cambridge 840E; at $900. CA$ (used), good luck finding anything remotely close to its amazing performance (and excellent resistor/relay vol. attenuation).

Happy New Year to you,

peter


The Tortuga Audio passive in kit form cost me Cdn$1,200 all in. The kit is well thought-out and easy to assemble, and is about Cdn$600 cheaper than the pre-built version.


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