Dennis Had Inspire Amps

[BearCityUSA]

Originally Posted by jscottyk

Hello Everyone, I'm new here and have not yet made a proper introduction over in Personal Introductions but I wanted to say a quick thanks. Recently I started exploring the idea of a SET tube amp and ran across you folks and the discussion of Dennis Had's most recent work. After a week of diving in I recently picked up one of this Fire-Bottle KT-88 amps from eBay. In a word, amazing. I'm still working my way through all 111 pages of this thread and learning a ton. Thanks for all the great information. -Scott

And welcome to the Inspire family.

This thread may be Dennis' best sales tool. Thank you Peter!

[Simonatsea]

Originally Posted by jscottyk

Hello Everyone, I'm new here and have not yet made a proper introduction over in Personal Introductions but I wanted to say a quick thanks. Recently I started exploring the idea of a SET tube amp and ran across you folks and the discussion of Dennis Had's most recent work. After a week of diving in I recently picked up one of this Fire-Bottle KT-88 amps from eBay. In a word, amazing. I'm still working my way through all 111 pages of this thread and learning a ton. Thanks for all the great information. -Scott

Welcome! These little amps are a bit of a journey. Warning...... May lead to a wee bit of tube rolling!!!! Enjoy!

[jscottyk]

Thanks for the warm welcome folks! I must admit I have a pair of KT150 and Sophia 274B to play with. Dennis sent a couple different driver tubes, 6DJ8 and a 6CG7.

My 'as sold' configuration is KT-88, with 6CG7 driver, and 5U4 rectifier.

[jscottyk]

Originally Posted by jscottyk

My 'as sold' configuration is KT-88, with 6CG7 driver, and 5U4 rectifier.

Forgot to include the pic.

[GeAllan70]

^^^



Nice!

[SteveSem]

Originally Posted by jscottyk

Hello Everyone,
I'm new here and have not yet made a proper introduction over in Personal Introductions but I wanted to say a quick thanks.
-Scott

Welcome, you will find this to be one of the most informative threads on an audio forum ever. It directly led to my purchase of an Inspire amp. I have benefitted greatly from the experiences of others trying a variety of tube combinations.

-Steve

[x3workshop]

Such a huge variety in the design of these amps. Mine was tweaked to take just about any tube I could throw at it with the right rectifier compliment. Was built right at the end of July.

You can see in the pics that the OT's are large air gapped units. The undercarriage pic shows how many chokes he's thrown in there. Quite the little beast.

https://www.dropbox.com/sh/t2usc8kti...AXzx-kd0a?dl=0

Have to say that I like it with the KT88's at the moment. Bringing a new pair of speakers on line in about two weeks and we'll see what tube mix it likes. I seem to have in my stash just about every power tube mentioned in this thread so far - even 807's, 6BG6's, 6K6GT's & 6098's.

EDIT: *Sorry, pics won't embed for some reason so a link to the dropbox file is included.

[robert_kc]

Greetings. I’m new to this forum. I recently acquired from Dennis Had an Inspire “Fire Bottle” SE Stereo Tube Amplifier HO, built in Oct 2015, and finished in copper color:

INSPIRE TUBE AMPLIFIER by DENNIS HAD FEATURING THE KT-88/6550 BEAM POWER VACUUM TUBE AMPLIFIER IN A SINGLE-ENDED CLASS A SET TRIODE DESIGN

• CLASS A, 8 WATT, ZERO-FEEDBACK TRIODE
• KT-88 GENALEX OUTPUT TUBES
• 6CG7 NOS INPUT DRIVER
• 5U4 Shuguang RECTIFIER TUBE
• REGULATED DC, B+ VOLTAGE ON DRIVER TUBE
• REGULATED DC POSITIVE CATHODE BIAS ON DRIVER TUBE
• CUSTOM DESIGNED AIR-GAP 15 WATT OUTPUT TRANSFORMERS TO MATCH KT-88 TUBES IN THE TRIODE MODE

Dennis tells me that he is finalizing his tube substitution chart for this amp. I’m anxious to start some tube rolling, and I’m interested in others’ experience with this amp.

Thus far (i.e., before any tube rolling) I like this amp with my Klipsch RF-7 speakers (basement system). My other speakers are: Klipsch Palladium P-37F (TV room), Snell Type CV (living room), and JBL L880 (office).

I generally prefer to use my power amps directly connected to the variable output of one of my Oppo universal players (i.e., no pre-amp). However, I do have McIntosh MX110Z preamps in two of my systems that I use when I need tone controls, and/or for additional gain with this SET amp.

I mostly listen to high-res (24bit/192kHz) recordings of classical music and opera, plus I occasionally listen to pop music artists such as Ella Fitzgerald, Count Basie, Tony Bennett, and Eva Cassidy. Thus far my Inspire KT88 amp sounds best with the pop music. I think this is because pop music often has much less dynamic range than large scale orchestral music. Also pop music is often mastered at much higher volume levels, and therefore the Inspire KT88 SET amp can achieve sufficient volume level with pop music – in contrast to some high-res classical recordings. Over the next few months I’ll conduct some tube rolling to determine if I can achieve enough gain to play classical music at a satisfying volume level with the Inspire KT88 SET amp, without using a preamp.

This is my first SET amp. (I own approx 2 dozen vintage push/pull tube amps, including power amps and integrated amps.) I’m glad that I finally started experimenting with SET, and I’m glad to own one of Dennis’ hand built amps. Plus Dennis is great to do business with!

I look forward to reading about others’ experiences with the Inspire SE Stereo Tube Amplifier HO – particularly regarding how to achieve additional gain in order to make it perform better for classical music - while preserving the tonal balance of the amp as-built by Dennis. (I have some different front-end tubes on the way. I’ll share my results soon.)

Thanks to everyone who has shared their experience with Dennis’ amps!

[pstrisik]

Beautiful amp - congratulations and welcome to the club! I love the copper color.

I'm curious about his SET wiring. I have a similar amp, but it is wired as SEP.

I have 93db speakers (single driver Omega Alnico Monitors) and need a preamp for sufficient gain. The obvious option is to get a matching Inspire preamp from Dennis. The cost is reasonable. My LP-2 is top notch. I used to have the Cary SLP-05 (one of Dennis' earlier designs that won awards). When I got the amp, I got the pre so I would have the matching set. I went back and forth between the Inspire and Cary preamps trying to hear the Cary as sounding better since it cost me five times as much as the LP-2 (about 9 times the price at MSRP!). I sold the Cary.

I'm also curious what he will say about tube possibilities in a SET that runs pentode power tubes. Maybe the same options as the SEP's, ie, almost infinite! Or maybe the SET wiring makes for more limited options.

If you are running it with Klipsch speakers, you have some advantage in gain as they are typically 100db+ aren't they? But evidently you are still needing more for classical. If you are running without a pre, do you have a passive attenuator? How are you controlling volume?

If ok to run in your amp, the 5AR4 or 5Z4 rectifiers are low voltage drop and may help hold the dynamics more (if I understand correctly how that works in operation).

[jdandy]

robert kc.......Welcome to Audio Aficionado.