If you want a tube preamp you should check out Conrad-Johnson. They have a low output impedance of 100 ohms and will work fine with your Pass amp.
http://conradjohnson.com/current-products/
http://conradjohnson.com/current-products/
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
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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- 111 posts total
Guys, I should point out that though the rule of thumb isn't bad, it's also not precise, and cannot account for personal taste. Yes, it seems like the amp's input impedance is a little low.... but the combination may work out spectacularly. Personally I think the best Pass amps are those matched with other pre's. Best, E |
If the design of the Calypso hasn’t changed significantly since Stereophile measured it in 2005, especially with respect to the value of its output coupling capacitor, neither it nor the Hovland is an ideal match for the Pass X350.5. Not so much because of distortion concerns, but primarily because of the deep bass rolloff and other sonic issues that are likely to result from the output impedance rise of both preamps to high values at 20 Hz. As Tony (Tls49) correctly emphasized. It is of course always possible that a non-ideal match might be subjectively preferable in a given situation, depending on listener preference, and especially if the non-ideality works in the direction of compensating for an issue elsewhere in the system or the room. But why take a chance by introducing a known and predictable issue into the system? It’s usually best to address the root cause of any issues that may be present, rather than trying to compensate for them. Regards, -- Al |
To add to my previous post: What can often be more significant than the ratio of the two impedances, as defined at the worst case frequency (which is usually 20 Hz for preamps having capacitively coupled outputs, which means most tube preamps as well as at least a few solid state preamps), is how much **variation** there is in the preamp’s output impedance over the frequency range. And in that respect what is by far the worst case situation among the two preamps that are being considered occurs at the balanced output of the Calypso, where "the balanced output impedance was 112 ohms at 1kHz and above, this increasing to 3900 ohms at 20Hz due to the finite physical size of the output coupling capacitors." Differences in how preamp output impedance **varies** over the frequency range are IMO probably the main reason that some people report good results when the 10x guideline is compromised, and others do not. The less variation the better, if the 10x guideline is not met at 20 Hz or any other audible frequency. Regards, -- Al |
Thanks guys - this is great stuff... I knew I would get great feedback from you guys. Excellent - thank you !!! Al, you are right, both of these are poor matches for sure. I like being able to look at the specs and get feedback from people that understand this better than I. I know enough about it to ask for help and feedback. Both these pres seem to be poor specs matches even though I know they may sound great. The only reason I don't want go to a Pass preamp is because I really want to try and get tubes into the chain. I am getting new to me speakers delivered on Monday. Magico S5's and many of the folks tell me their sealed box design can really benefit from warming a little warming up of the lower midbass being one not used to the speed and type of bass these offer. Little tube richness in there plus I love tubes but know to properly drive Magico's would cost a fortune with tubes. Heck the Pass X350.5 is pretty close to a tube amp so a tube pre with this amp should make a tube lover happy - I hope :) My buddy told wanting tubes try and find a tube amp that can both get the desired output impedance and preferably one without a cathode follower. Those tend to cause different impedance swings verse a pre uses tubes in paralell to lower impedance. In my price range what do you think of a BAT VK50SE. It is in my mid $2k price range and people speak high of them. Some say they can be a bit dark but people that combo with Magico speaker might be a nice match. There is a 51SE but its a $1,400 more and out of what I want to spend. What do you guys think? Thanks so much! |
- 111 posts total