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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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fsmithjack OP
712 posts
 
No problem - this one easy - the Triode Lab 2A3S-FFX wiped the floor of the Yamamato in every single way. More linear, dynamic, incredibly smooth and one of the best audio amps I have ever heard. The Yammy is a great amp and does so many things well but the Triode Lab is in another league.

Frank at Triode labs is amazing and one of the best people I’ve ever dealt with anywhere with any brand. Super friendly and will support you to end of earth and then on the other side as well. Love that guy!

To better the Triode Lab you will need to get into the AudioNote, Kondo, Shindo gear at 5x10x20 times the price, These companies gear at similar price point isn’t even close. You need spend way more. No body is making anything, anywhere in Frank’s prices that comes close. His trannies, chokes, caps, wires, resistors are all the best and everything is hand made by him. Could go on and on about this creamy gear. I have shifted gears and decided to try the other end of the spectrum but I am sure I will own his gear again. I liked it too much!
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fsmithjack OP
712 posts
 
UPDATE::

The guys on Ayre K-1xe got cold feet. He was kind of on the fence and decided not to sell :(

Back to the drawing board :( just got to wrapping my mind around a SS preamp.

What do you guys think - should I just get the Pass Labs XP10

Oh BTW Nelson got back to me on the BAT I was considering and he told me those specs for the bass roll off get extreme right at about 20hz because thats when the caps run out of steam but at mid, higher 20.s,it will be in safe range and he said the Magico S5's bass should roll off before the BAT does / close but close matters so he said don't get caught up with those numbers because the BAT is very good for tube amp/ Now this was only on the BAT as it is way better than the Hovland or Calypso. The BAT is better than these. 

What do you guys think? I guess we are mere mortals when it comes to Mr. Pass. He shrugged it off like no worries at all.

Hmmmm

What do you guys think - I didn't get too deep into with him but not sure he know the Magico S5 are 22hz speakers. I think they go lower than the majority of speakers but of course others go lower but just thinking out loud with you guys. 
 
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almarg
9,670 posts
 
I guess the bottom line re impedance compatibility with the BAT is that a reasonable case could be made on either side of the issue.

Earlier in the thread I referred to the possibility of audibly significant phase shifts occurring as a result of the impedance interactions that would arise using the BAT with your amplifier, in addition to a slight amount of deep bass rolloff. If I recall correctly Ralph of Atma-Sphere has said in past threads here that to be sure that audibly significant phase shifts will not occur frequency response should extend beyond the audible range by a factor of 10, meaning 2 Hz to 200 kHz. While his designs meet that requirement, at least at the low frequency end (and at both ends in the case of his preamps), obviously many well regarded designs do not. All or nearly all SET amps for starters. (I note, btw, that your X350.5 is specified down to 1.5 Hz).

And in this case, given that the preamp’s output impedance rises from 414 ohms at mid-frequencies to 4600 ohms at 20 Hz, it will not come close to supporting bandwidth down to 2 Hz in conjunction with a 30K load.

So it seems to me that while use of the BAT in this application represents a compromise in terms of impedance compatibility, the degree of that compromise is sufficiently marginal that its acceptability is something reasonable (and knowledgeable) people can differ about.

Regards,
-- Al

lewinskih01
909 posts
 

@fsmithjack 

Thanks for the quick and clear answer! The chances of finding someone having heard these two amps were pretty slim, yet I got lucky.

Did your FFX have the Hashimoto output and power transformers?

On pictures these amps look good. How are they in reality?

BTW, Frank has been great to deal with.

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