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Best passive preamps

50.82.119.167
Posted on February 7, 2016 at 11:45:26
johns dad
 Please let me know which passive preamps you think are best. I am not asking for opinions about passive versus active preamps. I have an active preamp at the moment and want to try a passive. This is for my second system which will be paired with a brand new Pass XA 30.8 amplifier which I am still burning in but am happy with so far. I am familiar with Placette products but have never heard one in my home. Factory direct with a home trial period would be ideal.

 

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Tortuga Audio, posted on February 7, 2016 at 13:19:29
Ewalaa
Audiophile

Posts: 504
Location: Central VA
Joined: December 10, 2000
 No sure about a trial, but the LDR passive is great.

 

David Slagle's Emia NT, posted on February 7, 2016 at 16:49:53
jnr
Reviewer

Posts: 2164
Location: San Francisco Bay Area
Joined: April 5, 2000
 l
theaudiobeatnik.com

 

RE: Best passive preamps, posted on February 7, 2016 at 17:31:55
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 Placette has that factory direct trial. I bought my Placette linestage, passives are not preamps, used and Guy at Placette repaired it free and offered to change the resistor values to better suit my setup. Pretty cool. As a resistor ladder with 127 volume positions via remote I think it's best.

However depending on your gear especially your sources output voltage and impedance you may or may not be a good candidate for a passive. What are your sources? Perhaps an auto former is better suited if you need a little gain. Pass says the input impedance but not the input voltage required for full output. I hate that.

So tell us all your sources so we know if most passive will work for you or if you need one with some gain like a transformer based one.

ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: Tortuga Audio, posted on February 7, 2016 at 17:34:28
johns dad
 Thanks will visit the website.

 

RE: Best passive preamps, posted on February 7, 2016 at 17:34:44
tgibbs
Reviewer

Posts: 86
Location: Atlanta Metro
Joined: April 10, 2003
 I use a Luminous Audio Axiom passive pre -- they're hand built with only the finest materials, and you provide all the particulars on your amps so that the chosen resistor value will mate perfectly with your system. The price is anywhere from about $200 to $500, depending on your desired options which include single-ended or balanced connectors, multiple inputs if so desired, and the quality level of the components. Mine is balanced with the Caddock resistors, and it's as transparent and revealing as anything I've ever heard -- truly state of the art. You won't be sorry.

Tom

 

RE: David Slagle's Emia NT, posted on February 7, 2016 at 17:43:05
johns dad
 Thanks! Despite the best effort of their website to dissuade me I will send them an email.

 

RE: Best passive preamps, posted on February 7, 2016 at 17:55:15
johns dad
 My only source at this time is a Sony APL heavily modded transport running through a Thor Audio DAC with old stock tubes. I use the top Analysis Plus cables. I have a very good vinyl front end but am too lazy to set it up and wont buy a new phono preamp for fear I will never use it.

 

RE: Best passive preamps, posted on February 7, 2016 at 18:49:25
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 Can't find any info on Thor Audio on the net

ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: Best passive preamps, posted on February 7, 2016 at 19:22:15
johns dad
 The company is no more. This design was a Paul Marks & Jerry Ozment (sp?) design. It is very good even by today's standards. The late Jerry Ozment was the brain behind Audio Logic.

 

RE: Best passive preamps, posted on February 7, 2016 at 20:04:52
Des
Audiophile

Posts: 2110
Location: Great Barrier Reef
Joined: August 3, 2000
Contributor
  Since: August 2, 2000
 Yes Jerry also designed the superb Jadis Dacs--I'm for trying the Slagle--give them a trial

I know Dave--quirky but hey his Transformers are acknowledged

as some of the best out there

may be best to call him.

If you have deep pockets Music First outa the UK are well renowned

Good luck

D

 

RE: Best passive preamps, posted on February 7, 2016 at 20:23:50
PAR
 I have heard quite a few passives (including Placette) and certainly prefer those with transfomers rather than a ladder of resistors

Of the transformer types Music First are very good but are also expensive. The Townshend Allegri is just fabulous and (when I last looked) well priced for what it is. However I don't know about availability in the USA. Why not give Max T a call?

 

RE: Tortuga Audio, posted on February 7, 2016 at 20:28:43
hahax@verizon.net
Audiophile

Posts: 4310
Location: New Jersey
Joined: March 22, 2006
 The potential problem with passive preamps is problems driving the interconnects and amp due to an impedance mismatch. If this problem occurs for you the sound will be dead. This can occur with a passive that is essentially a just a conventional volume control, either continuous or stepped. If you try one of these, be sure to use one with a return policy.

If you find a mismatch you need a passive with controlled output impedance, onw with either transformer outputs or with a multi tapped autoformer used as the volume control. The problem here can be cost. Good transformers and autoformers cost.

A possible used idea is the old Melos SHA headphone amp which also can be used as a 2 input line stage. It can be used with gain, totally active or in a semi passive form. It allows the user to bypass the gain stage but not the cathode follower which is only there for impedance matching. It was about $1100 years ago and should be relatively cheap now. There were a couple thousand made. And even in active mode it got rave reviews as a line stage.

 

RE: Best passive preamps, posted on February 8, 2016 at 02:08:04
Solidcore
Audiophile

Posts: 374
Joined: April 19, 2001



I use one of those - Khozmo passive preamp - and like it very much.

Rgds Jan

 

2nd that......., posted on February 8, 2016 at 03:57:07
Ozzy
Audiophile

Posts: 7594
Joined: September 21, 1999
 .....great passive line stage.

Oz



Don't worry about avoiding temptation. As you grow older, it will avoid you.
- Winston Churchill

 

Good candidate for passive, posted on February 8, 2016 at 04:46:43
Jack G
Audiophile

Posts: 9740
Joined: September 24, 1999
 Your source, cables and amp are fine, assuming your speakers are reasonably efficient.
The Placette will work well, as will any other passive.
Jack

 

RE: David Slagle's Emia NT, posted on February 8, 2016 at 05:50:56
louie3
 If you can find a used Sonic Euphoria (autoformers) they are superb, very well built and not expensive.

My experience with Pass amps indicates they need a little bit of gain, but maybe not with your digital set up.

 

Check this out, posted on February 8, 2016 at 05:55:09
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 I was recently discovered these passives.

Three things I really like about them:

1 - there is a remote control option.
2 - there is also a shunt option. That means only TWO resistors in the path at any given position. As opposed to a ladder type that "adds" resistors to the audio path continually to attenuate.
3 - It has a sharp looking little box.

 

RE: Best passive preamps, posted on February 8, 2016 at 09:54:28
jec01
Audiophile

Posts: 1462
Location: Baltimore, Maryland
Joined: September 22, 2004
 Given that you have a Pass power amp, you might want to take a look at the First Watt B-1. Reno Hi Fi will give you an in-home trial.

Happy listening,

Jim

"The passage of my life is measured out in shirts."
- Brian Eno

 

While there are many good quality passives, posted on February 8, 2016 at 10:18:14
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 how well they work depends almost entirely on your setup.

The source impedance, the amplifier input impedance, the length and type of cables and of course the actual value of your control all play a role. It really does boil down to math- so much so that the math itself tends to play a bigger role than how well built the passive control actually is.

This is why you see so much comment on this topic, as results are all over the map.

Generally speaking, most passives tend to reduce bass impact at anything less than full volume. This can be reduced by placing the passive control as close to the amp as possible- preferably inside it. To really make this work and be convenient a remote control would be handy in case you run monoblocks.

The math: the lower the value of the control, the less it will be affected by the choice of cable. The lower the value of the control, the more the source will be affected by it. The longer the cable at the output, the more capacitance will affect it, especially if the control is of a higher resistance (extreme higher values can interact with Miller effect at the input of many amplifiers). Quite often if there is a coupling capacitor at the output of the source, the passive can act like a bass filter at anything less than full volume.

These factors can overcome what the passive control is made of, which is why many very inexpensive controls sound just as good as really expensive ones. Or it can go the other way! Anybody who plays with such controls knows how important it is to use the right cable... bottom line is YMMV!

 

I'm using my Emia with a Pass 30.8 NT, posted on February 8, 2016 at 10:52:33
jnr
Reviewer

Posts: 2164
Location: San Francisco Bay Area
Joined: April 5, 2000
 .
theaudiobeatnik.com

 

RE: While there are many good quality passives, posted on February 8, 2016 at 11:44:13
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 Doesn't amplifier sensitivity play a role too? I've seen amps that need only a volt at 100K ohms input impedance and others, more often tube gear that need 2.5 volts or more and maybe at as little as 20K ohms input impedance.

ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: Best passive preamps, posted on February 8, 2016 at 12:49:09
jdwaudio
Audiophile

Posts: 383
Location: Connecticut
Joined: July 22, 2000
 The Tisbury Audio is a very good passive especially for the price. They are generally listed on EBAY.

 

not only does amplifier senstivity play a role, posted on February 8, 2016 at 12:53:47
Ralph
Manufacturer

Posts: 4778
Location: Minnesota
Joined: April 24, 2002
 -So does source output level.

 

RE: While there are many good quality passives, posted on February 9, 2016 at 06:00:53
airtime
Audiophile

Posts: 11287
Location: Arizona
Joined: February 4, 2003
 "Generally speaking, most passives tend to reduce bass impact at anything less than full volume. This can be reduced by placing the passive control as close to the amp as possible- preferably inside it"

I find that my passive actually has MORE bass. My preamps act more as an impedance "leveler". That's what I'm "assuming" - and we all know what happens when we assume - you make an ASS out of U and ME! When I use a passive on my some of my amps the treble gets spiky and the bass is stronger than normal.

It's a kind of you gotta try it and see.

I always recommend a person to test out a passive first. If a radioshack is available you can cobble together a passive for $10. Or if you a dealer allows a 30 day free trial. But you have to try it with YOUR system. Sometimes it works. Sometimes it doesn't.

 

RE: not only does amplifier senstivity play a role, posted on February 9, 2016 at 12:24:24
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 Yes I've had my 2.35 VRMS @50 ohms through a resistor ladder to a passive bi amp where each amp has an input impedance of 100K where 2V will deliver full power.

There is a rare occasion when a CD recorded at a low level will not allow me to light my peak lights on any passage of the music.

With my 4 mV Grado, 54dB gain phono pre @1000 ohms I was also fine with a few occasions where a few recordings could have used a bit more umph.

ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: I'm using my Emia with a Pass 30.8 NT, posted on February 9, 2016 at 12:26:30
Awe-d-o-file
Dealer

Posts: 21037
Location: 50 miles west of DC
Joined: January 10, 2004
 The Emia looks nice. What's your source(s)?

ET
ET

"If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

 

RE: I'm using my Emia with a Pass 30.8 NT, posted on February 9, 2016 at 14:25:46
jnr
Reviewer

Posts: 2164
Location: San Francisco Bay Area
Joined: April 5, 2000
 A SoundSmith Stain Gauge cartridge and a 47 labs cd player

theaudiobeatnik.com

 

RE: Best passive preamps, posted on February 9, 2016 at 19:15:37
sqlsavior
Audiophile

Posts: 55
Location: New Mexico
Joined: June 25, 2013
 If you go with a transformer-based passive, you are much less likely to have impedance mismatch issues. It then becomes a matter of whether your sources have enough oomph.

I sure like my Promitheus TVC.

http://www.promitheusaudio.com/tvc.htm

 

RE: Best passive preamps, posted on February 13, 2016 at 17:38:18
Rzado
Audiophile

Posts: 75
Joined: September 5, 2001
 Hi johns_dad,


As a passive enthusiast (I have owned more than a dozen passive of various iterations over the years), I cannot believe I missed this thread. The big question is whether you have a cap on your budget. If price is unlimited, the two best I have heard, hands down, are both transformer based: the Silver Rock (with the silver wired magnetics) and the Ypsilon PST-100. They outperformed (in some cases by a significant margin) passives from Placette, Audio Synthesis, Reference Line, Promitheus, Music First (although have not tried the Reference), several LDR type passives, the old McCormack Line Drive, etc. However, neither option is cheap - the Silver Rock is $5k, and has only one input; the deluxe unit (SWGLA) with a buffered output and multiple inputs is over $18k; the Ypsilon will run $28-38k.

In addition to the above, while I have never gotten the chance to listen to the Emia in system, I have heard great things, and Dave Slagle is a true gentleman, so I would also recommend you give the Emia a try. (I understand that Dave got his motivation / inspiration for his autoformer product from Serge at Silver Rock).

If you are looking for something on more of a budget (~$2-3k), the Promitheus Signature is a good choice - I regret not keeping my old unit around.

Best of luck.

 

RE: Best passive preamps, posted on February 14, 2016 at 05:15:13
johns dad
 I appreciate your response. I contacted Slagle, Music First and Townsend over a week ago and got no response so these manufacturers are out of the running. Unless they get back to me with a viable excuse I will never work with them.

I ended up buying a Tortuga and it should arrive next week. I am most interested in determining if I can live with a passive. If I can live with a passive then I will experiment with other types in the future. I have a client that is willing to send me for audition both a Slagle and a Prometheus.

I will try to update this forum with the results of my foray into the passive realm.



 

THANKS TO ALL FOR YOUR HELP! nt, posted on February 14, 2016 at 05:16:08
johns dad
 nt

 

RE: Best passive preamps, posted on February 14, 2016 at 10:13:58
arrjmai
Audiophile

Posts: 4
Location: Bangkok
Joined: January 5, 2016
 I use silk transformer passive pre-amp from SAC Thailand. it's really good. I installed 0.47uf Mundorf sg oil output coupling cap on my DAC. My power amp are 2 x firstwatt j2 parallel mono. The transformer is about million k input and very low just a few k output. The sound is really good as SAC has also supply transformer to some hi-end expensive product on the market. The price is reasonable here as I don't need to pay for the shipping. The company locate near by my house.

 

RE: Best passive preamps, posted on February 15, 2016 at 20:39:50
dave slagle
Manufacturer

Posts: 5430
Location: NYC
Joined: April 27, 2001
 Hey,

A friend pointed me here. I didn't see an email. Can you contact me through the asylum or try the email again. I understand that you chose another direction and thats cool but it bothers me that somehow an email fell through the cracks or was caught by a spam filter.

dave

 

RE: Best passive preamps, posted on February 16, 2016 at 06:39:00
johns dad
 Thanks Dave! Email sent though AA.

 

RE: Best passive preamps, posted on February 19, 2016 at 13:01:39
pictureguy
Audiophile

Posts: 22597
Location: SoCal
Joined: October 19, 2008
 You could ALWAYS do a DIY starting with a pair of GoldPoint attenuators? Add a selection of premium connectors and good wire, than worry ONLY about a nice case. Find a woodworker friend to take care of the last.
Too much is never enough

 

RE: Tortuga Audio, posted on April 10, 2016 at 19:31:44
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 So the potential upsides of a passive are the quieter background?

Is it a downside that your amp will need to work harder? If so, do the plusses outweigh the minuses?

 

RE: Tortuga Audio, posted on April 24, 2016 at 20:57:51
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 anybody?

 

RE: Tortuga Audio, posted on April 25, 2016 at 11:27:54
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 Dang...this is not a very helpful forum.

 

RE: Best passive preamps, posted on April 25, 2016 at 17:36:26
audioaddictNY
Audiophile

Posts: 51
Location: 10543
Joined: March 21, 2011
 I was aThor dealer many years ago and sold the preamps amps and DACS.
Jerry was the genius behind the DAC, it was really a great product and sounded terrific.

Thor has been out of business for many years now, but some of their product does come up now and then on Auduogon and it was very good tube equipment, the preamp was especially good.

 

RE: Tortuga Audio, posted on April 26, 2016 at 13:24:42
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 Hi All,

Full disclosure, I'm with Tortuga Audio so discount what I say here as you see fit.

The caution regarding impedance mismatch and passive preamps, while not without some basis, has proven to be a non-issue as a practical matter with our LDR passive preamps over the past 3 years. I really can't point to a single instance where a customer ran into a impedance mismatch issue.

As long as you have a reasonably decent impedance bridging ratio between your amp's input impedance and your source's output impedance you'll get very good results with a Tortuga. "Decent" is not a hard and fast number but I'd say if you have 50:1 or better you're good to go. So if you have a 20k amp that means any source with 400R or lower output impedance. Our development/testing rig has a 20k input with a 600R DAC. That's 33:1. No problem.

Cheers,
Morten

 

RE: Tortuga Audio, posted on April 26, 2016 at 14:53:32
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 Thanks for the reply.

But the amp will need to work harder vs an active pre to achieve the same volumes, correct? And amps typically have higher distortion at higher output, so does this negate the improvements gained with the "quieter" passives?

Thanks.

 

RE: Best passive preamps, posted on April 26, 2016 at 15:48:29
6bq5
Audiophile

Posts: 4391
Location: SF Bay
Joined: August 16, 2001

I have a Schiit SYS which I have used in a variety of configurations and like it very much-
If I were to spend more on a passive Pre- I would most probably build my own using Goldpoint stepped attenuation and selector.
Happy Listening

 

RE: Tortuga Audio, posted on April 26, 2016 at 15:55:03
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 An amp really doesn't know whether it has a passive or an active preamp providing its input. It only "sees" a voltage signal. Most amps have input coupling caps so it only sees the AC (dv/dt - varying with time) signal and not the DC although some amps can be direct DC coupled as well. Point is, an amp is basically a voltage multiplier. How hard it works is entirely dependent on the magnitude and frequency of the incoming voltage signal.

On the other hand, your source (DAC, phono stage etc.) definitely "sees" the preamp it's connected into. Your source has to deliver its voltage signal into the impedance (AC resistance) of the preamp. In the case of active preamps, that impedance is defined entirely by the preamp itself. In the case of most passive preamps, the source sees the effective impedance of both the preamp and the amp connected in parallel. So all things being equal, having a passive will often present a lower effective impedance for the source. Lower impedance means the source has to put out slightly higher current while delivering its voltage (the audio) signal.

As long as your source has a reasonably robust output stage and the net effective parallel impedance of the preamp/amp is stays sufficiently high, your source isn't overtaxed and sound quality doesn't suffer. It's been our observation as borne out by our customers that as long as the passive preamp's own impedance is sufficiently high, that over taxing the source has not been an issue.

The classic complaint about passive preamps/attenuators is they don't deliver as good dynamics and/or bass compared to actives. This may be true for some passives. It certainly is not the case with the Tortuga LDR passives.

 

RE: Tortuga Audio, posted on April 26, 2016 at 18:26:13
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 Thanks again for the information. I appreciate the tutorial. My amp has a 1V input sensitivity for a 28.2V gain. So I understand that the output voltage (and dB's) will be dependent on the input voltage. But if the amp is at max power but with an input voltage of say 0.5V instead of 1V, will it have the same IM and THD?

Just trying to figure it all out and understand what the potential benefit is of a passive.

 

RE: Tortuga Audio, posted on April 26, 2016 at 19:19:51
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 Whether your amp is driven from a passive or an active preamp has nothing to do with your amp's distortion performance. Your amp will put out the same volume at 0.5 volts in regardless of what device is delivering the 0.5 volts or whatever voltage. Also, at 0.5 V in your amp will only put out 14.1 V.

The potential benefits of a passive has nothing to do with your amps distortion characteristics. It has to do with eliminating the noise, coloration, distortion, artifacts and veil that most active preamps put out. And it's rare that you need any actual gain (amplification) from your preamp. A possible exception is if you have a very low wattage (3-5 W) tube amp driving not so efficient speakers. In that case you might actually need some preamp gain to get decent volume out of your speakers. But that's a fairly unusual scenario in my opinion.

Among passives you will be hard pressed to find better performance than an LDR passive. The difference is due to how LDRs perform relative to other resistive materials such as resistors or pots. In the final analysis audio is subjective. I was personally amazed the first time I heard an LDR attenuator several years ago. Since then I've observed that most people have similar reactions.

 

RE: Tortuga Audio, posted on April 26, 2016 at 19:42:06
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 I meant that the distortion increases with output, I believe. So what I'm trying to figure out is if the distortion would be higher at 14V from a 0.5V input vs 14V from a 1V input.

 

RE: Tortuga Audio, posted on April 26, 2016 at 19:45:55
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 Doesn't work that way. If you put 1v in you'll get 28v out. You put 0.5v in you get half of that out. That's baked into your amp design.

 

RE: Tortuga Audio, posted on April 26, 2016 at 19:58:18
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 Yes, I understand that, but the voltage gain from the amp is still the same 28X in both examples. Does that mean the amp is working at full load in both cases and therefore max distortion in both cases?

 

RE: Tortuga Audio, posted on April 26, 2016 at 19:59:38
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 to clarify further, in the second example (14V with 1V in, I'm assuming the volume is turned only half way up.

 

RE: Tortuga Audio, posted on April 26, 2016 at 20:21:04
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 Constant gain but not constant power. Let's assume you have a 80 watt amp and you have 8 ohm speakers. Power = IxIxR. So I^2 = 80/8 = 10. Square root of 10 is 3.16 amps. Power is also VxI. So at full output the voltage output would be 80/3.16 = 25.3 volts. If we also assume you amps power supply is +/- 25 volts you would be right at the clipping point so hopefully it's closer to 30 to provide some headroom. What this means is by the time you put 1v in to your amp you are already running flat out. But normally you are likely to only run at around a few watts at most which means your preamp will be attenuating that source voltage way down below 1v to achieve lower power output with reasonable sound pressure level.

 

RE: Tortuga Audio, posted on April 26, 2016 at 20:32:11
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 Ugh. We don't seem to be communicating, unfortunately. That's OK. I'll do some Google searches/research and figure out the answer to my question. I think I'm correct: lower input voltage from a passive means the amp needs to work harder for the same output voltage vs an active. And that means a higher THD (and other distortion). Not sure if that outweighs the benefits of a passive vs active (subjectively or otherwise), though...

 

RE: Tortuga Audio, posted on April 26, 2016 at 20:38:19
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 Sorry if I haven't been more clear. To be blunt you are mistaken in your assumption that a passive somehow outputs a lower voltage say compared to an active at a given volume level of output. That's just plain wrong. If your amp needs say 0.2 volts to produce a reasonable loudness from your speakers then that's voltage your preamp will produce be it a passive or active.

 

RE: Tortuga Audio, posted on April 26, 2016 at 20:43:47
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 No problem. It's undoubtedly my misunderstanding. I have both a passive and active pre, and the active is WAY louder, which makes sense. I'm just trying to piece together the rest of the story...

 

RE: Tortuga Audio, posted on April 26, 2016 at 20:54:26
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 The active is capable of producing louder output because it has its own gain. It's a small amp in front of a large amp but has an attenuator (volume control) to throttle it down. When either of your preamps produce the same listening level they are both delivering the same input voltage to your amp (aha!!!)

It you had a corvette and a Ford Fiesta the corvette will go much faster. But to run them both at 60 mph you will have to push the throttle down further on the fiesta and only a little on the corvette. Not a perfect analogy but close.

 

RE: Tortuga Audio, posted on April 27, 2016 at 05:14:15
CaptainWatt
Manufacturer

Posts: 27
Location: South Florida
Joined: March 22, 2014
 If your amp has a fixed sensitivity (gain ratio) of 28Vout/1Vin then the only way you get 14Vout is with 0.5Vin. If your source device (say it's a DAC) puts out 1V, then the preamp would need to attenuate that 1V source signal down to 0.5V in order for your amp to see 0.5V in. Doesn't matter what type of preamp, passive or active, is doing the attenuation. However, your active preamp, especially if it has some built in gain of its own, would be attenuating more to achieve a 0.5V output.

 

RE: Tortuga Audio, posted on April 27, 2016 at 13:47:52
jrdoe
Audiophile

Posts: 114
Joined: April 14, 2015
 So a half-dozen or so posts on this topic and the only response are from the manufacturer of the Subject Title? What's wrong with this forum?

 

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