Dennis Had Inspire Amps

[x3workshop]

Ei KT90's. Anyone have any experience with them? I may give a pair a try.

[Rosco65]

My last experience with them was in a pair of converted Luxman MB3045's. I owned them so long ago (1993?) that I have no meaningful memory of their sound.

[x3workshop]

I'm picking up several from someone I know clearing out an estate. I'm very curious to give them a listen. I've heard very good things about them being run in Triode mode.

We need to start a tube lending library. So many tubes/brands...

[Simonatsea]

Originally Posted by x3workshop

Ei KT90's. Anyone have any experience with them? I may give a pair a try.

They are currently my favorite tube choice in my 6V6 amp.
They seem to do everything very well, good extention on both ends, great imaging. I prefer with the 596 rectifier. Tried going back to my POPE 6v6 but they seemed soft and slow by comparison. Pushing hungry speakers though, KEF LS50's

[Simonatsea]

Anyone tried thier Inspire amp with Quad ESL 57's?

[Coltrane1]

Originally Posted by pstrisik

Price on this amp lowered to $1750 overnight. Perhaps Aurelio/Dominguez is reading here! Helloooo Aurelio/Dominguez!

Hi Peter,

The KT150 on Audio Mart is now $1450. Is that the amp you're referring to? Do you recall what that amp sold for in 2014? Still enjoying yours or have you moved on?

Thank you!
C1

[Rosco65]

Originally Posted by Coltrane1

Hi Peter,

The KT150 on Audio Mart is now $1450. Is that the amp you're referring to? Do you recall what that amp sold for in 2014? Still enjoying yours or have you moved on?

Thank you!
C1

I remember seeing the seller reference the original Ebay ad when he bought it from Dennis. If memory serves, he paid $1,350 for it.

For reference, Dennis most recent sale for a KT88HO with IIPS was for $1,434 including shipping. I'm still scratching my head at the seller's asking price.

[Rosco65]

Does anyone know how I (or Dennis) could limit the bandwidth of a KT88HO amp to function as a tweeter amp? I know some people use Harrison Lab FMOD filters that are 12dB/octave inserted ahead of the amp. I am looking to limit the amp to above 6 to 8khz, 6dB/octave.

One option is to insert a capacitor of the correct value in line with the amp. This would require me to know the input impedance. Another option would be to choose a smaller coupling capacitor value in the amp itself to limit LF response.

I'm toying with crossover options for my Altec 414A/802D setup. Current options include Joe Esmilla's crossover, Joe Roberts' recommendation of a single cap at 6-8khz with attenuator (l-pad or autoformer), or and active/passive solution using two amplifiers. I have an LP-27a preamp (two outputs), a PSE amp (15 wpc or so), and a KT88HO (5 wpc with 6V6 to 12wpc KT88). I could use one amp with a speaker-level crossover or both amps by limiting the low frequency response of the "tweeter" amp. The power difference between the two would almost perfectly match the sensitivity difference of the drivers (99dB vs. 105dB).

Any thoughts or suggestions?

[pstrisik]

Originally Posted by Coltrane1

Hi Peter,

The KT150 on Audio Mart is now $1450. Is that the amp you're referring to? Do you recall what that amp sold for in 2014? Still enjoying yours or have you moved on?

Thank you!
C1

Hi Greg,

Been a while! I am still enjoying my KT150 big time. Dennis upgraded it a couple of months ago to employ his infinite impedance power supply and Jantzen Z-Silver caps. Very significant improvement.

That is the amp I saw. He lowered the price twice. Down to $1450 about the time we talked about it here. Hasn't sold so far, so the price still is on the high side. Still might sell at that price, but you're right, Dennis' current offerings are a better deal than that one used at that price. The price for mine in early 2014 was $1650 shipped. That was $1550 plus $100 for custom powder coating color. Since he is charging for shipping, it is very close to the $1550 new price at the time I bought mine.

[pstrisik]

Originally Posted by Rosco65

Does anyone know how I (or Dennis) could limit the bandwidth of a KT88HO amp to function as a tweeter amp? I know some people use Harrison Lab FMOD filters that are 12dB/octave inserted ahead of the amp. I am looking to limit the amp to above 6 to 8khz, 6dB/octave.

One option is to insert a capacitor of the correct value in line with the amp. This would require me to know the input impedance. Another option would be to choose a smaller coupling capacitor value in the amp itself to limit LF response.

I'm toying with crossover options for my Altec 414A/802D setup. Current options include Joe Esmilla's crossover, Joe Roberts' recommendation of a single cap at 6-8khz with attenuator (l-pad or autoformer), or and active/passive solution using two amplifiers. I have an LP-27a preamp (two outputs), a PSE amp (15 wpc or so), and a KT88HO (5 wpc with 6V6 to 12wpc KT88). I could use one amp with a speaker-level crossover or both amps by limiting the low frequency response of the "tweeter" amp. The power difference between the two would almost perfectly match the sensitivity difference of the drivers (99dB vs. 105dB).

Any thoughts or suggestions?

You are aware, as I am doing it partially from your input, of the discussion over here: audiocircle.com/index.php?topic=146274.0 (I am assuming Rosco65 and Roscoe65 are both you).

One cap speaker level in front of each tweeter. I'm waiting for a pair of 1.5uF caps for about 16kHz high pass. I don't have the sensitivity, but the impedance is 6.5ohm for calculating resistance with a tool like this: learningaboutelectronics.com/Articles/High-pass-filter-calculator.php.

I will try with an active solution: Temple Audio Bantam Gold amp that has attenuator built in, and with a passive solution running from the main amp (Inspire) and a free standing Shiitt SYS attenuator. (Hmm, forget the Shiitt SYS for this - it's line level . I will need a speaker level attenuator, which I do have from an old project).

A while back, I asked Dennis about limiting the low end response of the KT150. He had a solution to high pass at 110Hz. Whether something similar can be done at much higher frequency, I don't know:

Simply add a 100K , 1/2 watt resistor from pin #6 to ground on the KT-150 tube socket. This will start a natural roll-off internally at 110 Hz with the signal down 3 dB at 60 Hz. This will not change the the output phase angle like adding series caps on the input.