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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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kalali's avatar
kalali
1,977 posts
 
A constant 250 ohm impedance across the entire frequency range into a downstream 30K ohm impedance should be okay, don't you think? I thought the major swings in the impedance are to
almarg's avatar
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almarg
9,670 posts
 
Fsmithjack, re the BAT VK-50SE (the reference in JA’s measurement writeup to VK-500SE appears to be an error), given my previous comment you would have a balanced output impedance of 4.6K at 20 Hz driving a balanced input impedance of 30K (or perhaps 29K), which is a ratio of a bit more than 6. You would also have a very wide variation in output impedance over the frequency range (from 414 ohms to 4.6K). Not ideal, and personally I wouldn’t risk introducing a compromise like that.

The Atma-Sphere preamp that was suggested would certainly be fine in terms of impedance compatibility (Ralph’s designs do not have capacitively coupled outputs), but I don’t know if it would provide the warmish sonic character you appear to be looking for.

Regards,
-- Al

jperry
2,444 posts
 
OP,

Reading through this thread it seems that you are reading reviews, listening to advice from others, and looking at specs for components.

My suggestion is that you call Reno HiFi. They have new, used and demo product from Pass. They allow you to demo, and return if not satisfied. Get a Pass preamp and try it in your system.

I don't own any Pass (I have an Aesthetix preamp and amp), but you already have the Pass amp, so I would recommend trying a Pass preamp.

Good luck with your search.

Jim Perry
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fsmithjack OP
712 posts
 
OK - so I am committed to make the BAT work if you guys think it will. I emailed Nelson also. 

That said:

I can get a Pass Labs XP-10 for similar price but with my Magico S5 Speakers everyone says the lean sounding lower midbass can really be helped with the tubes.

Not that Magico S5 bass is lean but the sealed cabinet is an adjustment for folks like me used to warmer ported sounds.

Plus I love tubes and thinking best to keep some tubes in there I think that will be more toward my liking but I have never heard the Pass XP-10 and if it will be that much better match wise maybe I just go for that?

Wish I could try it out in my system but buying used so not possible.

Thanks Al Kali - buying used and really just looking at used pre's that are available today via the Agon, the Marts and the bay and are under $3k is how I have come up with the ones I am thinking about.

Trying to not make a mistake and give my speakers the chance to sound their best. I will try my Bricasti direct also but I have always found I love preamps. Maybe it is mental but the Bricasti is also known to be at its best when volume is wide open and a pre does the attenuation chores imo ymmr. 

I will update everyone with what Nelson thinks but would love what you guys think - also maybe there is another pre i am overlooking or something.

You guys are the best of the best. This is the best place for audio anywhere. 
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