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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
fsmithjack

Showing 9 responses by jmcgrogan2

jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Pass Labs X350.5 amplifier with input Impedance 30k ohms Balanced or 20k ohms Single ended*

I believe that you have those two numbers reversed. The way I read it on the Pass Labs website:
Input Impedance (SE & BAL Kohms)   30/20.

The way that reads to me is that the Input impedance is 30Kohms for SE, and 20Kohms for BAL.

Still, the fact that the Hovland output impedance rises to 4.3 Kohms at 20 Hz would make it a poor choice for even an amp with a 30K input impedance. I would think a 50Kohm amp would be the minimum for the Hovland.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
John, I’ve noticed that apparent anomaly in the specs of the Pass .5 amps in the past, and I’m pretty certain it is a mistake in the specs, and what was intended was 20K single-ended/30K balanced.

Al, thanks for your input. I might have to contact Pass directly to get the true numbers.
I just assumed that the 30K SE/ 20K BAL was correct because of Threshold history.
Many old Threshold amps had a SE input impedance of 50Kohm while the Balanced inputs were rated at 600 ohms input impedance.

https://www.stereophile.com/content/threshold-stasis-sa12e-power-amplifier-specifications

Also, Coda amps, which were designed by 3 ex-Threshold engineers, always had very low balanced input impedances as well.

The spec sheet on the Model 15/15.5 shows an SE input impedance of 50K with a Balanced input impedance of 1K ohms.

http://coda.cc/product/index.php

So I just assumed it was something in this family design that always had the balanced input impedance lower than the unbalanced input impedance.

It does look like Nelson has addressed this flaw with the .8 series.

Cheers,
John


PS: I see in Stereophile's measurements of the XA60.5 amps they measured a 17K input impedance in both SE and BAL. Who knows which figure is right?

https://www.stereophile.com/content/pass-labs-xa605-monoblock-power-amplifier-measurements
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
The Ayre and the Pass Labs are both great SS preamps. They will both work great with the proper surrounding components.
That said, I find it odd that you have heard that the Pass Labs unit can be sterile, while no one finds the Ayre to sound that way.
This does not mimic my impressions, but c'est la vie.

Personally, I have no desire to ever return to a SS preamp.
However, if forced to pick a SS preamp, my clear preference would be a 7 series unit from Klyne Audio Arts.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
BAT VK-51SE
BAT VK-32SE
CJ ET3SE
CJ CT-6

Any thoughts - think I'm leaning toward the BAT VK-32SE

I called BAT they said its the sweetest of the BATS and have same bass and dynamics as the others. The 51SE a little more neutral but the Magico's seem to be looking for a bit of sweetening.

I've owned the VK-51SE, VK-50SE, VK-31SE, and had the VK-32SE in my home for a one week audition.

I would agree that the VK-32SE is the sweetest sounding preamp of the BAT bunch, but it did NOT have the bass and dynamics of the VK-51SE.
Unfortunately in life, one can't have it all. I preferred the VK-51SE in my system.

In the end, I sent the VK-32SE back to the dealer, too sweet for my tastes.
I wound up buying an ARC Ref 3 instead. Now this was about 9 years ago.

I've also owned a CJ Premier LS 16 mk II, which was also a sweet sounding tube preamp. A bit more refined sounding than the VK-32SE, but the VK-32SE did have more power and dynamics than the CJ.

I would think if you are looking for sweetness, either CJ preamp, or the VK-32SE would be best suited for you.

The VK-51SE has more dynamics and power than any other preamp on your list, and though it may sound warm compared to ARC or VAC preamps, it is not as warm as the other 3 preamps on your list.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Well Magico speakers have a reputation for being very revealing speakers.
I am familiar with your amp, and yes it is known to be a warmer sounding amp.
I am not familiar with your source though. Perhaps you may be better off with a tubed DAC, like a Lampizator.

Then again, maybe there is nothing you can do to ever make the Magico's work for you. You are at a fork in the road. Should you try a warm tube preamp and warmer cables to help tame the Magico highs?
Or just cut bait and sell the S5's now?

I wouldn't make an impulsive decision, think about it for a while.
A Cary/CJ preamp and some Purist Audio or Kubala Sosna cables could save the S5's. However, if they do not, then you may need to go further and try a tubed DAC too.

I have a friend who loves his S5 Mk II's. He is using them with Vitus CDP and electronics, and Jorma Prime cables.

Good luck,
John
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
As I said earlier:

A Cary/CJ preamp and some Purist Audio or Kubala-Sosna cables could save the S5's.

Also,looking at the pictures, there is a nice spot on that top shelf - right side for a turntable. ;^)
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
I'm happy to read that your patience has paid off.
I would leave the Pass Labs X350.5 plugged directly into the wall.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
Hmm, you bought the BAT VK-32SE because you complained that the S5's were too bright. I warned you just how warm the VK-32SE was.
I'll also tell you that Kubala-Sosna Emotion cables will be warm sounding, possibly even warmer than the Cardas Clear Reflection.
I understand that you may fear too revealing cables like Nordost, but with K-S, you went the other way, IMHO.

As for a more neutral preamp, of the SS preamps you mention, the Ayre K-1xe would probably offer the most resolution.
If looking for another tube unit, look for a VAC or ARC preamp, both offer higher resolution than BAT.

Let these items settle in before making a final judgement. For instance, even though the Emotion cables may be warmer sounding, you may like them once you get a more resolving preamp.

One change at a time works best for me.
Too many changes at once can lead to mass confusion.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
I've never heard an Esoteric preamp, so I cannot comment.
I do recall owning a Mark Levinson 38S for about a month.
I did not care for it at all, sold it as quick as I could.
That was probably about 12 years ago though, and I never had the desire to buy another ML product.
Could have just been a synergy issue, as ML does have it's fans, just like any other brand.

Personally, I can live with a SS amp, but I need a tube preamp.
If you want SS, look for a Klyne 7 series preamp.
Rare and hard to find, but the best SS preamp I've ever heard, and that includes brands like Rowland, ML, Krell, etc..
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