2. amps-preamps
  3. 131753-4121

PLEASE match Advice Pass Labs X350.5 (20k) to Hovland HP-100 (2500ohms) Miss-match ???

GUYS / GALS NEED YOUR HELP PLEASE!

A friend said this preamp is outstanding and will sound great with Pass Labs amps and to not get caught up in the specs but the measurements say different.

Pass Labs X350.5 amplifier with input Impedance 30k ohms Balanced or 20k ohms Single ended* 
(*source Pass Labs Manual)  

Hovland HP-100 source impedance 2500ohms* 
(*source Stereophile) 

Guys / Gals, can I used my Pass Labs X350.5 amp with Hovland HP-100 preamp? Has anyone used Pass amps with Hovland pre's. I will be using Magico S5 Speakers and Bricasti M1SE DAC but want it to sound the best it can. Should I just stick with the Aesthetix Calypso pre I was leaning toward before my gut said to go for the Hovland HP-100

Hovland HP-100 Preamplifier: * Output impedance: approximately 2500 ohms or according to Atkinson, Hovland HP-100 (2500ohms) its source impedance was high at 2.4k ohms, rising to 4.3k ohms at 20Hz. The partnering power amplifier would best have an input impedance of at least 47k ohms if the bass is not to sound lean*. The Pass Labs doesn't meet the x10 requirement it is supposed to but it is sort of close when looking at it. What do you guys think? I am not sure what to do but you guys will know what to do?

Stereophile: Its input impedance was a usefully high 100k ohms in the midrange and bass, with just a small reduction to a still-high 86k ohms at 20kHz. Despite the claim that the HP-100 uses a cathode follower output stage, its source impedance was high at 2.4k ohms, rising to 4.3k ohms at 20Hz. The partnering power amplifier would best have an input impedance of at least 47k ohms if the bass is not to sound lean.

Read more at https://www.stereophile.com/content/hovland-hp-100-preamplifier-measurements#YZXZfGLbbL2COkLR.99 https://www.stereophile.com/content/hovland-hp-100-preamplifier-measurements#YZXZfGLbbL2COkLR.99
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yogiboy's avatar
yogiboy
5,615 posts
 
I think you should. Why take the chance?
tls49's avatar
tls49
1,351 posts
 
Yes, definitely a bad match. You have the answer in your post.

"The partnering power amplifier would best have an input impedance of at least 47k ohms if the bass is not to sound lean*."

I had experience with a bad matching pre/power. In addition to lean bass, it also sound lifeless, no dynamics. When I changed amps to a proper match and 1/3 less power, the bass was there and it was more dynamic with less power. Also, the first amp sound great with a correct matching preamp.
jperry
2,444 posts
 
You should consider a Pass preamp. It will be a great match with your Pass amplifier.
kalali's avatar
kalali
1,977 posts
 
I don't have anything to add to what's already been said but out of curiosity what's it about your Aesthetix Calypso that you feel needs improvement? That is supposed to be an excellent preamp.
joey54
434 posts
 
As much as I like the Aesthetix Calypso I tried using it with a Pass Labs 250.5 and it was not a good match. It seemed like something was missing from the music and I could not listen for long. I ended up trying an Audio Research Ref and that was a much better match. In the end I sold the Pass and bought an Aesthetix Atlas and kept the Calypso.

The best preamp I ever heard with the Pass was a Pass preamp. It’s been a while and I can’t remember which preamp it was but they go extremely well together as you would expect. 

This is is just my opinion and YMMV. Good Luck!
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