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Inspire by Dennis Had Enjoying Vacuum Tube Audio

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  #6031  
Old 10-11-2020, 04:14 PM
Ruleof72 Ruleof72 is offline
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Originally Posted by FloridaBoy View Post
What does your entire system consist of? I have 3 Inspire amps and none of them have that issue with 99db speakers.
Here's my system, though it doesn't appear that and of the other components add or subtract from the hum:

Technics SL-1210GR turntable
Lounge LCR MKIII phono preamp
Raspberri Pi streamer going to Schiit Modi Multibit via SPDIF
Oppo disc player going to Schiit Modi via Optical
Modi and Lounge going to NAD 326Bee Integrated (used as preamp for now)
Inspire Fire Bottle
12 gauge no-name speaker wire
Tekton Enzo XL towers

I've been trying different combinations and it seems to come down to the amount of time after the amp is powered up. Initially the hum becomes apparent about 10 seconds after the amp is turned on and diminishes to "slightly audible" (have to put my ear to the speaker) after about 20-30 minutes (when the amp is toasty warm). At that point it's a non-issue but during the first 20-30 minutes I can hear it from my listening position.

After floating the ground and reversing the polarity I don't think that either of those has a measurable impact. Other possibilities I came up with after some searching are:
1. Microphonics of tubes/transformer?
2. DC offset issues?
Don't know if either of them is applicable to me or not.

I love the sound of the amp it's just the slight hum in the initial half-hour or so that triggers my OCD-ness and makes me wonder what is going on.

Like I said, I'm a tube noob so any insight, suggestions would be helpful.
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  #6032  
Old 10-12-2020, 09:23 AM
FloridaBoy FloridaBoy is offline
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Quote:
Originally Posted by Ruleof72 View Post
Here's my system, though it doesn't appear that and of the other components add or subtract from the hum:

Technics SL-1210GR turntable
Lounge LCR MKIII phono preamp
Raspberri Pi streamer going to Schiit Modi Multibit via SPDIF
Oppo disc player going to Schiit Modi via Optical
Modi and Lounge going to NAD 326Bee Integrated (used as preamp for now)
Inspire Fire Bottle
12 gauge no-name speaker wire
Tekton Enzo XL towers

I've been trying different combinations and it seems to come down to the amount of time after the amp is powered up. Initially the hum becomes apparent about 10 seconds after the amp is turned on and diminishes to "slightly audible" (have to put my ear to the speaker) after about 20-30 minutes (when the amp is toasty warm). At that point it's a non-issue but during the first 20-30 minutes I can hear it from my listening position.

After floating the ground and reversing the polarity I don't think that either of those has a measurable impact. Other possibilities I came up with after some searching are:
1. Microphonics of tubes/transformer?
2. DC offset issues?
Don't know if either of them is applicable to me or not.

I love the sound of the amp it's just the slight hum in the initial half-hour or so that triggers my OCD-ness and makes me wonder what is going on.

Like I said, I'm a tube noob so any insight, suggestions would be helpful.
Can you take the amp somewhere and run it in another system? That would really help with solving the problem.
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  #6033  
Old 10-12-2020, 10:16 AM
bearcity bearcity is offline
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As I have mentioned here before I have been test driving the new CJ5 preamp for a while now. I am actually dreading returning it to Dennis so much the last I visited the shop to pick up my updated PSE I conveniently left it at home. I couldnít resist the desire to here my latest Inspire update driven by the latest Inspire Pre.

Letís back up a bit with a bit of my experience with Dennisís preamps. About 5 years ago I purchased an lp-2 on the used market to replace a Cary SLP-50 in my system. Since that time I have been lucky enough to upgrade the lp-2 to an lp-3a and purchase a lp-27a to drive an Inspire PSE. I have also been able to travel to Cary a number of times and had listening sessions with his lp-3.1 and the lp-76. Needless to say I have been well versed in the Inspire preamp lineage.

This begs the question; how do they all stack up?

The lp-2 is obsolete compared to the rest. The improvements Dennis continues to make have left that unit in the dust. For those of you who are still running an lp-2, itís time to upgrade IMO.

On a visit, not to long ago, I brought my lp-27a to compare to the lp-3.1. Though I have always liked my lp-27a, I sometimes think of it as an Ďan old manís preampí. An expression Dennis often uses when referring to triodes like 45s and 300Bs. The 27 is a beautiful sounding pre but lacking some of the punch of the 3.1. Anyway, Dennis and I did some really serious comparing of the two that day and in the end we both agreed that neither bested the other. Both presented the music equally as well, but different. One thing I would point out. The lp-27 is a tube collectorís preamp, in that it uses tubes that are not made any more. So if you are someone who loves the sound of tubes but does not have the patience for sifting through old tubes to find usable ones and would prefer to go with new production, get a 3.1 which runs 6SN7s.

The lp-76 was another strong temptation for me. Also a tube collectors preamp, it runs 76s. Not sure if we will see that on the market but I know Dennis purchased a case on NOS 76s a while back.🤔 I also understand the prototype CJ5 I have was an lp-76 reworked to itís current configuration, so I have my doubts.

As an aside, I listen to music differently than most reviewers I have read. I have a rather tin ear. I cannot breakdown what I am hearing into itís component parts nor can I typically tell what is missing or overly emphasized. The one thing I do have is a pretty solid reference to what actual instruments and vocals sound like. Decades of seeing live shows, with and without amplification, has given me that. My criteria for judgement is if the re-presentation is realistic to an actual presentation. That is it. The closest re-presentation I have heard to the real thing is a good recording, imprinted on vinyl, run through SE amplification into a single driver speaker.

That brings us to the CJ5, another tube collectorís preamp. Dennis came up with this prototype a few days before I was set to visit and deliver a pair of speakers I built for him. He was head over heals for this new unit. I had doubts. I know how something new often sounds great, maybe even the best I have heard, only to realize a while later that I have no idea why I was so enthralled. I have witnessed Dennis do the same. I took my lp-27a with me for comparison. We A/B compared the two several times and I could not deny the superiority of the CJ5. Damn it! Oh how he tempts me. He sent me home with the prototype. That was, it seems, a couple months ago as I reflect further. Pandemic time is disorienting... With the CJ5 I have driven my 6V6er, my PSE and now it is in my office driving my modified Universal. Hands down it bests my lp-27a and lp-3a. That is really saying something because each of those have an amazing presentation. Much better than any other preamps I have heard. The CJ5 has more detail and refinement than either of my other two Inspire preamps. More like the real thing. As the CJ5 is now close to market Dennis wanted me to get the word out that ďThe best preamp known to mankind will soon be a realityĒ. He may be right about that.

Scott
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  #6034  
Old 10-12-2020, 07:27 PM
rmlowz rmlowz is offline
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Posts: 26
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Thanks
Bearcity for the great write up and review. Might be something I need to save up for next.
I just ordered a new Inspire 45 today cant wait
Rich
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  #6035  
Old 10-12-2020, 11:41 PM
Jprod Jprod is offline
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Join Date: Nov 2018
Posts: 17
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Quote:
Originally Posted by bearcity View Post
As I have mentioned here before I have been test driving the new CJ5 preamp for a while now. I am actually dreading returning it to Dennis so much the last I visited the shop to pick up my updated PSE I conveniently left it at home. I couldnít resist the desire to here my latest Inspire update driven by the latest Inspire Pre.

Letís back up a bit with a bit of my experience with Dennisís preamps. About 5 years ago I purchased an lp-2 on the used market to replace a Cary SLP-50 in my system. Since that time I have been lucky enough to upgrade the lp-2 to an lp-3a and purchase a lp-27a to drive an Inspire PSE. I have also been able to travel to Cary a number of times and had listening sessions with his lp-3.1 and the lp-76. Needless to say I have been well versed in the Inspire preamp lineage.

This begs the question; how do they all stack up?

The lp-2 is obsolete compared to the rest. The improvements Dennis continues to make have left that unit in the dust. For those of you who are still running an lp-2, itís time to upgrade IMO.

On a visit, not to long ago, I brought my lp-27a to compare to the lp-3.1. Though I have always liked my lp-27a, I sometimes think of it as an Ďan old manís preampí. An expression Dennis often uses when referring to triodes like 45s and 300Bs. The 27 is a beautiful sounding pre but lacking some of the punch of the 3.1. Anyway, Dennis and I did some really serious comparing of the two that day and in the end we both agreed that neither bested the other. Both presented the music equally as well, but different. One thing I would point out. The lp-27 is a tube collectorís preamp, in that it uses tubes that are not made any more. So if you are someone who loves the sound of tubes but does not have the patience for sifting through old tubes to find usable ones and would prefer to go with new production, get a 3.1 which runs 6SN7s.

The lp-76 was another strong temptation for me. Also a tube collectors preamp, it runs 76s. Not sure if we will see that on the market but I know Dennis purchased a case on NOS 76s a while back.🤔 I also understand the prototype CJ5 I have was an lp-76 reworked to itís current configuration, so I have my doubts.

As an aside, I listen to music differently than most reviewers I have read. I have a rather tin ear. I cannot breakdown what I am hearing into itís component parts nor can I typically tell what is missing or overly emphasized. The one thing I do have is a pretty solid reference to what actual instruments and vocals sound like. Decades of seeing live shows, with and without amplification, has given me that. My criteria for judgement is if the re-presentation is realistic to an actual presentation. That is it. The closest re-presentation I have heard to the real thing is a good recording, imprinted on vinyl, run through SE amplification into a single driver speaker.

That brings us to the CJ5, another tube collectorís preamp. Dennis came up with this prototype a few days before I was set to visit and deliver a pair of speakers I built for him. He was head over heals for this new unit. I had doubts. I know how something new often sounds great, maybe even the best I have heard, only to realize a while later that I have no idea why I was so enthralled. I have witnessed Dennis do the same. I took my lp-27a with me for comparison. We A/B compared the two several times and I could not deny the superiority of the CJ5. Damn it! Oh how he tempts me. He sent me home with the prototype. That was, it seems, a couple months ago as I reflect further. Pandemic time is disorienting... With the CJ5 I have driven my 6V6er, my PSE and now it is in my office driving my modified Universal. Hands down it bests my lp-27a and lp-3a. That is really saying something because each of those have an amazing presentation. Much better than any other preamps I have heard. The CJ5 has more detail and refinement than either of my other two Inspire preamps. More like the real thing. As the CJ5 is now close to market Dennis wanted me to get the word out that ďThe best preamp known to mankind will soon be a realityĒ. He may be right about that.

Scott
To me Ďthe best preamp known to mankind ď is the don sachs linestage. If this comes close it will be deserving of accolades
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  #6036  
Old 10-13-2020, 11:36 AM
FloridaBoy FloridaBoy is offline
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Join Date: Jun 2015
Location: SW Florida
Posts: 1,090
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Quote:
Originally Posted by rmlowz View Post
Thanks
Bearcity for the great write up and review. Might be something I need to save up for next.
I just ordered a new Inspire 45 today cant wait
Rich
I have an LP27a and like it a lot. I could live with it, but Bearcity has me considering the CJ5.

Scott, do you know what the gain is for the CJ5? The LP27a is 12db with 27 tubes and 15db with 56 tubes.
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  #6037  
Old 10-13-2020, 06:07 PM
Tannoyd Tannoyd is offline
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Is Dennis doing a preamp with a remote?
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  #6038  
Old 10-14-2020, 07:59 AM
bearcity bearcity is offline
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Posts: 78
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Quote:
Originally Posted by FloridaBoy View Post
I have an LP27a and like it a lot. I could live with it, but Bearcity has me considering the CJ5.



Scott, do you know what the gain is for the CJ5? The LP27a is 12db with 27 tubes and 15db with 56 tubes.


The CJ5 is 15db gain, as is the 3.1.
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  #6039  
Old 10-15-2020, 09:51 AM
FloridaBoy FloridaBoy is offline
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Location: SW Florida
Posts: 1,090
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Quote:
Originally Posted by Tannoyd View Post
Is Dennis doing a preamp with a remote?
You have to ask him. Send a message via epay.
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  #6040  
Old 10-21-2020, 07:00 PM
rmlowz rmlowz is offline
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Posts: 26
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Hello
I was curious as to what NOS 45 tubes my forum friends have found that have a great sound. I ordered a Inspire 45 and know it will come with some excellent 45 tubes. I wanted to have some back ups. It appears I should buy them ASAP. The prices don't look like they are going down LOL. One forum member recommended new TJ wire mesh 45s. I was wondering what everybody has tried in their Inspire 45
Thanks
Rich
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