AudioAficionado.org  

Go Back   AudioAficionado.org > Manufacturers Forums > Inspire by Dennis Had

Inspire by Dennis Had Enjoying Vacuum Tube Audio

Reply
 
Thread Tools Display Modes
  #3891  
Old 06-25-2017, 10:58 PM
zip's Avatar
zip zip is offline
Junior Member
 
Join Date: May 2009
Location: northern Illinois
Posts: 7
Default

Anybody know the differences between the Had LP27 and the LP3 preamps ?

Sure would be nice if Dennis Had would have a website for information on his Inspire products !

Waiting days for email replies doesn't work well .........
Reply With Quote
  #3892  
Old 06-26-2017, 08:22 AM
Musica Amantem Musica Amantem is offline
Senior Member
 
Join Date: Nov 2015
Posts: 579
Default

I have only heard mine (LP-27a), so I don't know what the differences may be, although the revised LP-3 design is more recent so in any case it should incorporate the latest tweaks from Dennis.

I agree Dennis needs to provide more formal references on his offerings. I just hope he remembers all the different designs and variations issued over time to provide support when needed.

In the recent past, Dennis used to reply to mails pretty quickly, so I assume he's on leave or something. Be patient!
Reply With Quote
  #3893  
Old 06-26-2017, 09:04 AM
Musica Amantem Musica Amantem is offline
Senior Member
 
Join Date: Nov 2015
Posts: 579
Default VA 350B and the RED MOD Filters

Once again, gladly surprised with the performance of a usually tricky output tube, which needs to be accompanied by the right complement. Using the filters with these tubes for the first time improved their performance quite tangibly: Neat mids and highs, with a very nice base line. I concluded these now surpass the 6P3S-E just because of their larger body of sound and sound-stage derived from the 12 mA higher max plate current at 250 V in Triode connection over the 6P3S-E and all 6L6's out there.

In my rig, although 6V6's and 6L6's sound nice once again with the filters, anything over 56 mA and up to 150 mA Triode max plate current works the best. So, in order of preference: GL KT-77 (120 mA), GL KT-88 (150 mA), VA 6550 (150 mA), VA 350B (56 mA), Shug KT-66 (60 mA).

Curiously, the last two sound quite different, with the 350B beating the KT-66 by quite a margin in my book, although these two share nearly the same max plate current specs. Similarly, the GL KT-77 sounds much better than the second in that list, in spite of it loosing 30 mA to the KT-88.

Evidently, there are intangibles at work here (tube design, materials, inner structure, etc.) which I cannot explain. What I know, is up to the 350B in that list, all of them sound so good they make me enjoy my music very much.

I won't be bugging you guys anymore with my ramblings, as I just finished my dial-in process and do not expect more trial-and-error attempts. With those findings and my current gear, including the balanced signal (Z-Bit) and a nice collection of great input tubes and rectifiers, I'm done chasing the Holy Grail

Last edited by Musica Amantem; 06-26-2017 at 06:23 PM.
Reply With Quote
  #3894  
Old 06-26-2017, 03:13 PM
Rosco65 Rosco65 is offline
Senior Member
 
Join Date: Jan 2016
Posts: 273
Default

Quote:
Originally Posted by Musica Amantem View Post
I have only heard mine (LP-27a), so I don't know what the differences may be, although the revised LP-3 design is more recent so in any case it should incorporate the latest tweaks from Dennis.

I agree Dennis needs to provide more formal references on his offerings. I just hope he remembers all the different designs and variations issued over time to provide support when needed.

In the recent past, Dennis used to reply to mails pretty quickly, so I assume he's on leave or something. Be patient!
I think Alan said Dennis was on vacation. AFAIK, Dennis has always provided very little documentation for the Inspire line. Someone put together a manual of sorts some months ago (it is linked in this thread) and he has responded to me with a legend for the inputs on my LP-27a. He does provide a laundry list of parts choices in his auction descriptions. I think that if we want better ([more] documentation we would have to come up with it ourselves. A starting point would be to trace out the circuit(s) and draw it out and accompany it with a parts list. That would be pretty easy for an experienced tube tech, but not so much for someone like myself.
Reply With Quote
  #3895  
Old 06-26-2017, 08:31 PM
Analog Addict's Avatar
Analog Addict Analog Addict is offline
Member

 
Join Date: Jul 2016
Posts: 486
Default

Quote:
Originally Posted by Rosco65 View Post
I think Alan said Dennis was on vacation.
I stopped by the shop yesterday to go over the chassis layout with Strait Wire and lo and behold, guess who was working on Sunday?



I wonder what he's up to with that schematic? I won't give it away, but that's my handiwork on the paper....

Anyway, he was hot at work on this new amp, currently unspoken for....



If you can't tell, those are 2A3's on that amp.

Here's another new build, using 6L6s...



And the original prototype running 6V6s....



And the whole table of goodies....




Meanwhile, back at amateur hour, I'm playing with layouts....





Quote:
Originally Posted by Rosco65 View Post
AFAIK, Dennis has always provided very little documentation for the Inspire line. Someone put together a manual of sorts some months ago (it is linked in this thread) and he has responded to me with a legend for the inputs on my LP-27a. He does provide a laundry list of parts choices in his auction descriptions. I think that if we want better ([more] documentation we would have to come up with it ourselves. A starting point would be to trace out the circuit(s) and draw it out and accompany it with a parts list. That would be pretty easy for an experienced tube tech, but not so much for someone like myself.
Personally, I never give away information on Dennis' designs because there are already people in the far east buying the amps and trying to make a quick buck making copies.
But just realize that if someone publicly gives out info like that, he may not sell you any more gear.

Now as far as the LP 27 vs LP3, the 27 typically uses five pin triodes, 27s or 56s. The LP 3 typically uses octal 6**7 tubes such as 6SN7, 6SL7, 6BX7, etc.

Last edited by Analog Addict; 06-26-2017 at 08:38 PM.
Reply With Quote
  #3896  
Old 06-26-2017, 08:59 PM
Rosco65 Rosco65 is offline
Senior Member
 
Join Date: Jan 2016
Posts: 273
Default

Quote:
Originally Posted by Analog Addict View Post
I stopped by the shop yesterday to go over the chassis layout with Strait Wire and lo and behold, guess who was working on Sunday?



I wonder what he's up to with that schematic? I won't give it away, but that's my handiwork on the paper....

Anyway, he was hot at work on this new amp, currently unspoken for....



If you can't tell, those are 2A3's on that amp.

Here's another new build, using 6L6s...



And the original prototype running 6V6s....



And the whole table of goodies....




Meanwhile, back at amateur hour, I'm playing with layouts....







Personally, I never give away information on Dennis' designs because there are already people in the far east buying the amps and trying to make a quick buck making copies.
But just realize that if someone publicly gives out info like that, he may not sell you any more gear.

Now as far as the LP 27 vs LP3, the 27 typically uses five pin triodes, 27s or 56s. The LP 3 typically uses octal 6**7 tubes such as 6SN7, 6SL7, 6BX7, etc.
Agreed about keeping detail about the gear to ourselves unless it has already been made public. Some designers/manufacturers publically share their designs, right down to parts choices. Others do not. Good for both of them.
Reply With Quote
  #3897  
Old 06-26-2017, 09:54 PM
Musica Amantem Musica Amantem is offline
Senior Member
 
Join Date: Nov 2015
Posts: 579
Default

Now, that's a beefy power transformer on the PSE 6V6 prototype, much larger than the one with 6L6's ... Reasons?
Reply With Quote
  #3898  
Old 06-27-2017, 08:18 AM
straitwire's Avatar
straitwire straitwire is offline
Senior Member
 
Join Date: Jan 2014
Posts: 263
Default

That tall power trans is the original '59 C.G. Conn, it has a 12v filament and is used to power the amp and supply filament voltage as well as B+ thru an 8 pin socket type plug that has a 0A3 mounted in it now

Last edited by straitwire; 06-27-2017 at 03:50 PM.
Reply With Quote
  #3899  
Old 06-27-2017, 05:40 PM
BearCityUSA's Avatar
BearCityUSA BearCityUSA is offline
Senior Member
 
Join Date: Apr 2015
Location: Asheville, NC
Posts: 309
Default

To begin, my latest trip to Dennis' Toy Factory was every bit as enjoyable and memorable as my previous two. I went with a short list of topics to discuss, a couple questions, and a free afternoons worth of time. Like before, I left with greater understand and awe of DH's knowledge and background, answers to questions asked and of course many more question to ponder, research, and sometimes answer on my own.

I arrived around 1:00 and we immediately left for lunch (DH's treat). A good thing too since previously we had planned to do lunch but quickly got to talking and forgot lunch. We went to a delicious sandwich place and caught up on some personal stuff, laughed about a few things, rolled our eyes at some of Cary Audio's offerings of late (the variable color face plate on one of their SS products) and lamented the turns life can be dealt.

Back to the shop. During lunch I had inquired about the hum I am getting from my lp-3a (mod of an lp-2, ca. 2013). Dennis offered to look at it. We had discussed the troubleshooting I had done and I learned that the lp-2 circuit was absolutely silent. The lp-3a and lp-27a circuits both have an inherent 120hz hum. Insignificant until speaker sensitivity reaches about 100db. Testing later showed my LP-3a was running as it should. My issue was the speaker sensitivity (about 99-100db) on one of my setups. DH said other owners have had issues as well with high sensitivity speakers. I also have diminishing spikes at 180, 240, 300, and 360hz that DH could not explain nor could we recreate there at the shop. I have something in my house causing this. D said to ignore it. My bedroom system mentioned above this was not possible since the hum is significant from across the room. Later in my visit we (really DH) solved my problem in a wholly round about way though not intentionally. More on that later.

Sorry, back to the shop, we walked in and Dennis sort of flopped onto his stool and asked if I wanted to leave the lp-3a there for him to look at later. I said, "whatever you want", but got the feeling that my visit was soon to be ending and I would be continuing on my trip. I was wrong. I think the 12" Italian sub he had for lunch was sucking the energy right out of him. It did not last. He soon was hopping around as enthusiastic as I have seen him.

Before I left Asheville, while I was loading a few Inspire pieces, I thought why not throw my Omega RS7 monitors in the car as well. I know Dennis likes to audition different equipment and I was pretty sure he had not heard them before. They are very light so easily transportable. In the car they went. While Dennis was looking over my lp-3a I suggested I bring them in for a listen. He was agreeable. Louis had sent him a pair pf Omegas back in his Cary days. As he was inspecting them visually he said the cabinet work had come a long way and the the driver was totally different. He said that the set from years ago was not impressive. His description lead me to believe this was back when Louis was using Fostex drivers. Anyway we hooked them up to the latest Inspire PSE with the 3 voltage regulator 'tubes' outfitted with TAD 6L6s. The sound was much what I was used to. I have had them for a while. Extremely detailed through the mid range while falling off at the top and bottom. Rather beaming as all single drivers seem to be, so with proper room placement a narrow sweet spot can be achieved for good results. The speakers were set up on the table flanking the amp so really not showing their best. This is when things got really interesting. Dennis listened for about a minute and suggested they needed something. He headed for the back and his bench and quickly rigged up what I later learned was a rather broad notch filter and came back out and hooked it up to the left speaker with a couple of test leads. We a/b tested it with a balance dial on the SS pre he had there at the time (he shipped his shop Inspire Pre recently to a customer). What a difference. The mids were tamed greatly allowing the top and bottom to come through. Also the beaming was gone and the sound stage really opened up. Now Dennis was excited, food buzz gone he runs back and rigs a second one up. We hook that up. Things are getting better. Now he is unstacking boxes and a couple cheepo speakers off some stands so we can get to really hearing what these things can do. He is exclaiming that after all these years (60) in audio he still gets completely enthusiastic when it comes to "this stuff". A pure pleasure to watch. Mainly I am just trying to keep up. Helping where I can tweaking things a little to open up the room some and let the Omegas breath. Anyway we both were in agreement that this was a dramatic improvement to the presentation and really made the Omega shine. Dennis, ever the tinkerer says if you really want that top end sparkle add some rear firing tweeters. Before I left I had the two notch filters and tweeter specs with a simple crossover sketched on a piece of paper in hand. We listened to these for a while. Dennis likes the driver with his tweaks. He asked a couple times if I was leaving them there. I assumed he was kidding, at least partially. That morning I threw the Omegas in the car figuring to maybe give DH a listen to a product several of us here have thought to be a good compliment to the Inspire gear. I never once considered he would just, off the cuff, go and so dramatically alter them, IMHO, in such a positive way.

By this point I had my KT 66/88/120, ca. 2013, out of the car to suggest how we (by we I really meant he) might incorporate a second regulator tube for the IIPS upgrade and keep the existing tube rectification. This older KT amp is the same size as his current PSE chassis so there is lots of real estate. No big beal it turns out. Gladly he is having Tony punch some holes and relocate a choke. I thought I may have had to do the chassis work. I will post pictures and impressions of course.

He took the KT amp and notch filter back to the test equipment to show me what it was doing. We measured about -6db filtered off around 2,000hz tapering off in both directions to near 0db at 100hz and 10,000hz. Of course this lowers the efficiency of the speaker but the advantages are worth it. I have had them crudely rigged up in my office all last week to my LP-27a>PSE set up and the improvement is there. This same efficiency reduction makes my hum at home tolerable while I search for the source. I do have more listening to do before I permanently mount them internally. I am thinking of reducing the resistor value to lessen the db reduction. I think the mids may be tamed a little much for my set up. I do seem to trust Dennis' ear so I am likely to go ahead by heavily modding these Omegas with he rear firing tweeter as well.

Some other tid bits and thoughts. Of course these are my own opinions and observations so please feel free to


The bias switch on his older amps like my KT became a nuisance for him. Owners kept contacting him to debate that that a Kt66 tube sounded better set on Kt88 and so on. I did get that felling a while back that when asking what setting I should use for a given tube. The response was "which ever sounds best". I have since stopped asking.
There have been roughly 11-12 PSE amps made to date. Those that have one are a limited few. The new offering with the (3) voltage regulators is the same circuit as the previous symmetric design. Personally I prefer the asymmetry of the new one but that is just my professional subjective opinion and is purely based on aesthetics.
My 2013 KT amp sounds very muck like his newer Firebottles and Hotrods but with a bit more maturity. I have been running it 1,500-2,000 hours/yr for 2+ years so it is WELL broken in. The PSE is really in a different league. It's not just extreme limitations like loud volumes, or clipping, or lack of head room. It truly has a dynamic that is unmatched by the others at any volume. Its still entirely an Inspire sound but +++++.

This pretty much covers my visit. Like I said to start, great enjoyment was had by me. I hope Dennis enjoyed it half as much. If so, the next time I have the opportunity he will play host and friend once again.

One more thing. For those Omega owners here on this Inspire thread, PM if you are interested in the diagram for the notch filters.
Reply With Quote
  #3900  
Old 06-27-2017, 05:47 PM
BearCityUSA's Avatar
BearCityUSA BearCityUSA is offline
Senior Member
 
Join Date: Apr 2015
Location: Asheville, NC
Posts: 309
Default

Follow up photos:
My Kt next latest PSE
IMG_6186.JPG

Omegas an notch filter
IMG_6181.JPGIMG_6183.JPG

Photos of new IIPS octal socket in my KT.
Thanks Straitwire. Nice and clean.
unknown.jpgAttachment 1
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Audioaficionado.org tested by Norton Internet Security

All times are GMT -4. The time now is 03:03 AM.



Powered by vBulletin® Version 3.8.10
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
©Copyright 2009-2023 AudioAficionado.org.Privately owned, All Rights Reserved.
Audio Aficionado Sponsors
AudioAficionado Subscriber
AudioAficionado Subscriber
Inspire By Dennis Had
Inspire By Dennis Had
Harmonic Resolution Systems
Harmonic Resolution Systems
Wyred4Sound
Wyred4Sound
Dragonfire Acoustics
Dragonfire Acoustics
GIK Acoustics
GIK Acoustics
Esoteric
Esoteric
AC Infinity
AC Infinity
JL Audio
JL Audio
Add Powr
Add Powr
Accuphase - Soulution
Accuphase - Soulution
Audio by E
Audio by E
Canton
Canton
Bryston
Bryston
WireWorld Cables
WireWorld Cables
Stillpoints
Stillpoints
Bricasti Design
Bricasti Design
Furutech
Furutech
Shunyata Research
Shunyata Research
Legend Audio & Video
Legend Audio & Video