Does anyone use a Preamp to bypass HT

[misterdoggy]

I am using a CD to DAC to bypass in the Processor. I'm wondering if a good Preamp in the process might add something.

This would be just for stereo CD's of course. Any experience would be appreciated.

Ayre CD to Goldmund Dac to bypass Lexicon mc12b to krell fpb400cx

Would I get some more warmth ?

[krellfan]

Doggy,

I have a Pass X1 preamp in my system connected to some Krell amps. I have the EAD 8000 processor connected to a balanced input of the X1. So far it works very well and I am pretty satisfy with the result.
The X1 is a pretty good sounding preamp but the user interface takes some getting used to.

[grit]

You mean replacing the pre-pro with just stereo preamp? Probaby that would help. Something I've seen is variable output CD players hooked directly to the amp (I believe Jerry has a similar setup), completely bypassing ANY preamps/processors.

[misterdoggy]

This is what I was thinking. I thought the Preamp would be better "before" the processor then whatever comes from the CD portion goes right thru bypass.

The CD/DVD player has 2 outputs so one can go to the digital input of the processor for 5.1 DD DTS THX etc and the other output would send a PCM signal to a DAC to the Preamp.

Doggy,

I have a Pass X1 preamp in my system connected to some Krell amps. I have the EAD 8000 processor connected to a balanced input of the X1. So far it works very well and I am pretty satisfy with the result.
The X1 is a pretty good sounding preamp but the user interface takes some getting used to.

Krellfan,

Did you feel the Krells were a little "bright" beforehand. Did it warm up the sound a little. Also I don't understand if you used "all" the channels for the preamp or just the stereo. Are you using a separate DAC as well.

[neil w]

sorry

[krellfan]

Doggy,

ThePass X1 preamp is used only for 2 channel music. Adding the X1 made the sound a little warmer - slightly more tube sounding and less forward. I don't use a seperate DAC, I have a Wadia 861SE cd palyer connected tot he X1.

Looking at your setup, I would connect the MC12 to an input of a good preamp rather than the other way around. As good as the MC12 is, a a pure 2 channel analog preamp will sound better. Does your D1X have analog outputs or only digital. The analog output of the D1X is suppose to be excellent so if you have it, you might consider bypassing the Goldmund DAC. I know Goldmund is good stuff. A friend had a complet Golmund setup with Sonus Faber Amati speakers and it was a very good sounding system.

A couple of years ago, I made a balanced switch box with trigger input and this allowed me to connect two balanced sources tot he Krell amps and used the processor trigger output to select the source. This might also work for your system as well if your preamp doesn't have a bypass mode.

[Karma]

HI doggy,
For music, I use a an outboard tube DAC to a Krell KAV-280p stereo preamp to drive my Krell KAV-3250 power amp directly which, in turn drives the front left and right main speakers. The DAC receives the coax digital PCM signal from my Denon 3910 CD/DVD player.

For music, the main processor does not have to be turned on because it is not used. This created a problem for the subwoofer input which for music is the preanmp L And R outputs. This works fine but in order to get the LFE to the subs for movies, I have to switch the subs input. This scheme works great and keeps the signal path for music as clean and simple as possible.

Yes, the Krell preamp represents a major improvement over using the processor for music. For movies I don't care so much because the sound is not my primary focus although it is still very good.

Sparky

[misterdoggy]

Doggy,

ThePass X1 preamp is used only for 2 channel music. Adding the X1 made the sound a little warmer - slightly more tube sounding and less forward. I don't use a seperate DAC, I have a Wadia 861SE cd palyer connected tot he X1.

Looking at your setup, I would connect the MC12 to an input of a good preamp rather than the other way around. As good as the MC12 is, a a pure 2 channel analog preamp will sound better. Does your D1X have analog outputs or only digital. The analog output of the D1X is suppose to be excellent so if you have it, you might consider bypassing the Goldmund DAC. I know Goldmund is good stuff. A friend had a complet Golmund setup with Sonus Faber Amati speakers and it was a very good sounding system.

A couple of years ago, I made a balanced switch box with trigger input and this allowed me to connect two balanced sources tot he Krell amps and used the processor trigger output to select the source. This might also work for your system as well if your preamp doesn't have a bypass mode.

The D1XE is only a transport. I could upgrade for another $3000. Its already a $7000+ item. The Goldmund Dac is good, real good. The D1Xe only has digital outputs being a transport.

The switching deal sounds complicated. does it switch automatically or manually ?

So you would put the preamp after the mc12b. That wouldn't work for me as I would have volume issues between 5.1 and Stereo, where as if its before the volume can be cranked, so the mc12b adjusts. If its bypass it shouldn't be affected too much by the lexicon should it.

Maybe if the preamp was after the mc12b it could be at a fixed output for volume and just go up and down with the 5.1, but that might be tricky.

Before the mc12 ONLY Stereo is affected.After there are more variables.

[misterdoggy]

HI doggy,
For music, I use a an outboard tube DAC to a Krell KAV-280p stereo preamp to drive my Krell KAV-3250 power amp directly which, in turn drives the front left and right main speakers. The DAC receives the coax digital PCM signal from my Denon 3910 CD/DVD player.

For music, the main processor does not have to be turned on because it is not used. This created a problem for the subwoofer input which for music is the preanmp L And R outputs. This works fine but in order to get the LFE to the subs for movies, I have to switch the subs input. This scheme works great and keeps the signal path for music as clean and simple as possible.

Yes, the Krell preamp represents a major improvement over using the processor for music. For movies I don't care so much because the sound is not my primary focus although it is still very good.

Sparky

So its like 2 systems. What about calibrating levels. After you set the levels in HT, and you move the volume up or down on the Preamp while playing stereo, it must change your HT 5.1 sttings ?

[Hoffi]

Have you considered a Krell KCTx preamp ? It has a bypass mode for driving only your mains and will fit perfectly to your 400cx amp. You can also use the cast connections. I´m sure it will be a big improvement...

Hoffi

[misterdoggy]

Have you considered a Krell KCTx preamp ? It has a bypass mode for driving only your mains and will fit perfectly to your 400cx amp. You can also use the cast connections. I´m sure it will be a big improvement...

Hoffi

How would it fit in. Would the bypass be after or before the processor. This is what I am trying to figure out. I guess the last thing to touch the signal should be the Preamp, but the Volume would have to be "fixed" and controled from the Processor or it won't be in line with the 5.1 setting for levels in HT.

What are your thoughts

[Karma]

So its like 2 systems. What about calibrating levels. After you set the levels in HT, and you move the volume up or down on the Preamp while playing stereo, it must change your HT 5.1 sttings ?

HI doggy,
You are sharp! You caught the possible problem but it's not. I described the music side of the system. Let me describe the HT side. It uses the Krell preamp to solve the problem you noted.

For both music and movies the preamp drives the L & R channels through the Krell KAV-3250 power amp. When I go to HT, I select the AV receivers L & R preamp outputs on the preamps source selector switch (music is Input 1 and HT is Input 2). Preamp Input 2 is placed into the HT Throughtput mode and it stays in that mode forever until you change it. Thus, it's always ready to go.

This is a feature of the preamp to solve the exact problem you noted. In the HT Throughput mode, the preamps volume and balance are disabled. The gain of the preamp, when Input 2 is selected, is set to a value of unity or 1. It can't be changed with the preamps volume or balance controls. Thus, the receivers L & R preamp signals are delivered to the power amp at exactly the levels dictated by the receivers volume control and calibration values. This is how the calibrations are maintained. Of course, when one calibrates the system it must be done with this setup which is no problem. The receiver does not know the difference.

The last part of the puzzle is the center channel. My Krell KAV-3250 is a three channel amp. The center channel preamp output from the AV receiver goes directly to the 3250's third amp which drives the center speaker.

As you said, it is kind of like two systems but they merge at the preamp and the subwoofer manual input switch.

I think this system setup is a little hard to visualize but if you think about it, it makes sense. The result is a very pure and direct music system signal path but still provides good HT performace which maintains all calibrations and is simple to use. You only have to remember to switch the preamp inputs and switch the subwoofer inputs.

Sparky

[misterdoggy]

HI doggy,
When I go to HT, I select the AV receivers L & R preamp outputs on the preamps source selector switch (music is Input 1 and HT is Input 2). Preamp Input 2 is placed into the HT Throughtput mode and it stays in that mode forever until you change it. Thus, it's always ready to go.

This is a feature of the preamp to solve the exact problem you noted. In the HT Throughput mode, the preamps volume and balance are disabled. The gain of the preamp, when Input 2 is selected, is set to a value of unity or 1. It can't be changed with the preamps volume or balance controls. Thus, the receivers L & R preamp signals are delivered to the power amp at exactly the levels dictated by the receivers volume control and calibration values. Sparky

So the preamp has a bypass. When HT is selected the preamp is out of the mixture in bypass at a fixed gain. When CD is selected it comes directly from the CD to the Preamp.

Either way there is only one output to the Amp from the Preamp.

Is that about right. HMMMMmmmm I need to give this some thought.

[misterdoggy]

Aha more important to have a bypass in the preamp and bypass the L&R channels of HT.

Ideal: direct from the CD/DAC to the Preamp to Amp

HT DVD to Processor to Preamp (bypass) to Amp

they share the common L&R Amp trhu the Preamp

I think I've got it !!

[misterdoggy]

Is this the idea then ?

[krellfan]

Doggy,

Your second diagram is how my system is setup. Hoffi had suggested the Krell KCT and it might be a good option. Since the Krell amp has CAST and Balanced inputs, the KCT preamp can be connected to the CAST and the MC12B can connected to the balanced of the 400cx. If the KCT is turn on, the 400CX will automatically switch to CAST input.

The switch box that I was referring is automatic switching since it can be triggered from the processor such that when you turn the MC12B on, it switched in input.

[Karma]

HI doggy,
Wow! Nice drawing. Yes, you nailed it. There are a couple of minor details that are not accurate compared to my setup but none are show stoppers. What you have drawn will work.

The CD player and DVD player is actually the same unit. I drive the DAC from the players coax output. Because the player and the AV receiver are both Denon I can use the Denon Digital Link to provide 5.1 from the player to the AV receiver. Thus, both paths from the player are digital. This is just a detail that happens to fit for me.

The center channel connection is from the AV receivers center preamp out to the Krell KAV3250 third channel. But if one only has a stereo power amp, one could just as easily drive the center speaker from receivers center power amp just as you have it drawn.

You don't show the subwoofer connections which is an issue you will need to work out. I use a manual toggle switch to switch the subs (I have two of them used in a stereo mode for music and mono for LFE) inputs between the Preamps left and right stereo outputs for music or from the LFE receiver output for movies. I split the LFE signal to drive the subs.

Sparky

[ThomasW]

Your last graphic is exactly how my system is setup. I only use the processor for multi-channel, that maintains the purest signal for 2 channel.

[misterdoggy]

HI doggy,
The CD player and DVD player is actually the same unit.

You don't show the subwoofer connections which is an issue you will need to work out.Sparky

Sparky,

Actually My CD and DVD player are one unit with 2 digital outputs. 1 PCM and the other for 5.1, but in the drawing it portrays that they are separate because they are separate in the unit as well.

The subwoofer is of no consequence as it is self powered and will receive the signal from the processor.

I've redone the drawing to include sub.

I am happy to hear from "respected" members that use this config and will go this route too.!! Thanks Guys

I'm thinking about Pass Labs X2.5 as it has bypass with Gain made expressly for processors.

[misterdoggy]

What do you guys think about Audio Research Tube Preamps for warming up the sound. L25 or something like that

Any Experiences

[Karma]

HI doggy,
Well, the conversation comes around to Audio Research. I have owned ARC equipment for over 20 years. In that time I have had 3 different preamps and two power amps. Unfortunately, I have no experience with anything later than stuff that came out after the year 1995. My current ARC equipment was all designed in the middle 1980's. They are classic ARC designs.

Warm is a relative term. Later ARC sound, including mine, are not known for a warm sound. I think of ARC as being tubed Krell but better. Powerful, clean, detailed and utterly grainless. The only time "warm" really enters the discussion is when noticing the lack of solid state edge and grain. I think of ARC as being honest to a fault. They do not have that stereotyped tube softness but still have midrange to die for.

But ARC provides a kind of magic that is difficult to put into words. The soundstaging is spooky. Images do not lie on a predictable plane. Rather, they shift and move according to the dictates of the recording. This is the essense of the lack of signature. Their ability to dig into the texture of a sound defies belief. They are good tubes but not necessarily warm tubes.

Sparky

[misterdoggy]

Im thinking about the Audio Research L25 or ref 2 mk 2. I figure the ARC stuff will offset krell well. Unfortunately I don't have the luxury to try something out where I live.

What does anyone think about Accuphase for a Preamp

or Mark Levinson 38s or 380S vs Pass Labs x2.5 vs Audio Research L25 or Ref2mk2 (the most expensive don't want to go that route)

Im looking for warmth. I want to "influence" a bit, I don't want transparency or neutral.

I've narrowed my search to these 3.

[Karma]

HI doggy,
I would encourage you to listen to the ARC equipment if you can. They really are special. However, I have several warnings. I have mixed ARC with solid state equipment (Levinson, Rowland) and was not totally satisfied with the results. I know a lot of people use a hybred approach like this. It is tempting. For example, using a tube preamp with a SS amp. It offers the reliability of a tube preamp with the cost effectiveness and reliability of a solid state power amplifier.

But what I have found is the solid state amp partially negates the sound of the tube preamp eventhough the Levinson amp was very fine. I have gone in the opposite direction too with a Levinson preamp and an ARC power amp. Again, I found the same result but the sound was not identical to the opposite case.

I have concluded that one should go with all tubes or all solid state to gain the full advantages of either technology. For me, in an HT context, this puts tubes out of the picture. Too expensive, too complex, too many opportunities for bad tubes. If I had an unlimited budget though, I would choose tubes in a heart beat.

I don't want to discourage you. I know it is difficult for you to try equipment before buying. If you can afford the gamble of buying before listening, go for it. You may come to different conclusions.

One more thing. I never use my main ARC system for casual listening. When it's turned on, I'm there and listening in bliss. OTH, my HT system is used for casual listening constantly. What's the difference? The cost of tubes. My ARC D250 MkII Servo power amp costs around $1500 to completely retube. The 20 6550 beam pentode output tubes can yield somewhere between 1500 and 2000 hours of life before they need to be replaced. That's not a lot of hours if the equipment is used for casual listening on a regular basis. This is the primary reason I would not build my HT system around tubes. Especially since there are many fine sounding solid state alternatives. They may not give the ultimate sound but it still can be excellent.

Sparky

[misterdoggy]

Sparky,

Thanks for that advice. Sound advice I must say. Casual listening is what we do around here a lot. i would need a closet full of tube just for the family to watch TV in bypass. That would be a waste.

So Now its coming down to Mark Levinson 38s or 380s OR Pass Labs x2.5

Which one would influence some warmth. ?

[Karma]

HI doggy,
I can't speak about Pass Labs except I know they have a fine reputation and Nelson Pass is a friggen genius. When he left Threshold, they lost all direction and finally went under. Their guiding light had left.

I do have quite a lot of experience with Levinson. I don't have to say much. Simply one of the best. Smooth, grainless, precise, wonderful. Enough said.

Warm? I dislike that term because it is so difficult to know what is meant. Levinson is honest sound. It can't get better than that. For comparison, Krell offers the same level of performance but with a bolder, harder hitting sound. Levinson, I think, is a bit more delicate. I love them both and have chosen both. Two of the best.

Sparky

[misterdoggy]

Sparky,

If I say warm, think opposite of Bright. I just want to tone down the Krell a little. I was also looking at an older Accuphase c 275.

What do you think of the difference between the 38s and 380s

Krellfan spoke of Pass Labs as being warmer for his double fpb350mx's so I am thinking about that too. Its also less expensive for the buck.

[Karma]

HI doggy,
I don't find Krell to be bright. Makes me wonder if something else is afoot. How do you have your room treated? Have you gone after early reflections? Do you have carpeting and drapes? What about wall hangings? Diffuser panels? And there always are the bass treatments like ASC tube traps.

These treatment options can have a huge effect on the rooms tonal balance and the perceived spectral balance of an amplifier not to mention imaging and soundstaging. Room treatment is a lot less expensive than amplifiers and often is just what is needed.

Just wondering.

Sparky

[misterdoggy]

HI doggy,
I don't find Krell to be bright. Makes me wonder if something else is afoot. How do you have your room treated? Have you gone after early reflections? Do you have carpeting and drapes? What about wall hangings? Diffuser panels? And there always are the bass treatments like ASC tube traps.

These treatment options can have a huge effect on the rooms tonal balance and the perceived spectral balance of an amplifier not to mention imaging and soundstaging. Room treatment is a lot less expensive than amplifiers and often is just what is needed.

Just wondering.

Sparky

I hear ya. I'll be moving in the Spring so Room variants will have to wait. I'm sure it has a lot to do with it as my setup is kinda hanging in the middle of the room on an angle.

I was thinking about Preamps anyhow.

I've also been considering Ayre K5xe which is a good value for the buck.

Its too bad everything is much more expensive when you have to buy 240v. In some cases it doubles the price.

I was looking at a K5xe in the states for $2100 and one here in france is more than double for 4100 Euros = $5000

Its killing me. I'm thinking about just using the step down transformer for a preamp and it doesn't pull a lot of watts.

Have any thoughts on that ? Thanks for all your input, You obviously have a lot of experience to share.

[Karma]

HI doggy,
I don't see any reason why a step down transformer won't work. It sounds like a good idea. Just make sure to use the safety ground. I don't know the electrical codes where you live but almost everywhere in the west, a safety ground is part of every wall outlet. It's an importent feature to prevent electrocution in the event of a short inside the preamp.

I think you already know this but be sure the transformer can handle the current load. Sorry to be so mother-like but part of my job is being an Electrical Safety Officer. I have seen some incredibly stupid and dangerous things done. So, just be careful and everything should work fine.

Sparky

[JKalman]

I am using a CD to DAC to bypass in the Processor. I'm wondering if a good Preamp in the process might add something.

This would be just for stereo CD's of course. Any experience would be appreciated.

Ayre CD to Goldmund Dac to bypass Lexicon mc12b to krell fpb400cx

Would I get some more warmth ?

The Ayre CD player has balanced outputs doesn't it? If you could do balanced connections all the way through to the amp, it would make a very nice difference. I wouldn't pass it through your MC-12 though. I would buy a preamp that would allow you to hook the MC-12 up to it and have it bypass through the preamp instead, thus you can have the CD player or DAC hooked directly to the preamp, and the HT would have its own hookup to the preamp. This would be a much cleaner stereo setup and HT setup. At least in terms of great stereo music over HT.

[krellfan]

Doggy,

If you decide to go with a Pass Lab preamp, it can be converted to 230V and Pass has great customer support. They sent me drawings on converting a Pass X250 amp from 120 to 230V for a friend that moved to Asia. It was a fairly easy procedure that required resoldering a couple of wires to the transformer. You can buy a US version and save some $$$. Shipping should not be too expensive since the preamp is not that heavy. If you need technical help, let me know. You should check with Reno Hifi at renohifi.com for Pass equipment. He is a great guy and very helpful and he may even convert the voltage for you.

[krellfan]

Doggy,

Try covering your flat display with a blanket - medium thickness. It'll tame the brightness down and improve imaging. I have my plasma covered when listening to music. Give it a try.

[misterdoggy]

Krellfan,

I sent you a PM !!

I saw someone named "krell fan" on a German-Belgium website selling a KCT. That wasn't you was it at one time was it.

From what I know about Pass Labs is the Market is very protected and they don't do conversions like Krell and others to protect the overseas marketplace.
They probably make exceptions for a "real" story like someone moving to another country.

I would love to know I could buy one there and convert it. I've seen some great prices on audiogon. Too bad the schematic you have is for an Amp and not the X1 or X2.5.

I did the soldering on a Hafler 500 back in the late 90's and it was also just a matter of wiring. Krell uses proprietary chips to protect their equipment at 50 or 60hz and its more complicated and you can't get the chip. I used tohave someone do it for me, but that dried up.

Also: "Original" 230v is better for resale than rewired, but rewired is not bad.

I will ring up renohifi.com and ask if they can be of help and thanks for the heads up.

Karma,

I know about being safe using grounds. In Europe or in France where its 230 we have 3 wires, 2 for current and one for ground in our plugs. thanks for worrying about me though. Somebody is worrying about me !!

[misterdoggy]

Another question. If someone is searching for complete transparency, then why have a preamplifier at all.

I am running thru bypass in the mc12b. Isn't that transparent.

Or this bypass isn't transparent and I need a preamp to be transparent, because there is some "coloration" of some sort coming from bypass going thru the MC12.

I mean, I've read reviews about some preamps that cost $5k and the word used the most is "transparent". Why pay 5k$ for nothing "air"

[Karma]

HI doggy,
Not all bypasses are created equal. There are different ways to implement it; expensive and cheap. In the case of the Krell KAV-280p preamp, relays are used to implement the gain change and alter the signal path. This is the expensive way.

My Denon AV receiver does it differently. Here an analog circuit called an "Analog Switch" is used. They are pretty good and are used extensively where signal quality is not of absolute importance. But it is an active circuit (not exactly but kind of like an amplifier with a gain of 1) which can and is characterized by its performance limits. This is the cheap and most common way especially in less than top end equipment. Best to avoid if possible.

Relays, done right, are much better since there is less opportunity to corrupt the delicate audio signal. This and a thousand other very definite things are the reasons that some equipment costs more than others.

But, in the final analysis, the simplist signal path is almost always best. There are some restrictions even here because the reality of physics imposes itself. For example, will that nifty passive circuit drive the necessary cable capacitance? And the list goes on. Blanket statements will almost always prove wrong in specific cases. Only our ears will reveal the truth .

Sparky

[misterdoggy]

Have you listened to the Kav 280p. ? I wonder how it woud compare with a Pass Labs x2.5 or x1. Can it handle class "A". ? I saw a used X2.5 going for the same price $1600 as a kav 280p + or - for both of those models. The KCt is more than I want to spend. Another contender is the Mark Levinson 380S but thats twice the price

[ThomasW]

I currently use a Ayre K5xe. The Ayre replaced a passive preamp made with the biggest stepped attenuator Shalco makes. In absolute terms the passive pre is the most 'transparent' device I've ever heard. The Ayre replaced the passive pre because I run long IC's. Long IC's and passive preamps don't work well together.

Using a step-down tranny to power a K5xe should be fine. It's a good preamp, but not $5k good. FWIW the list price when I bought my K5 (about 18mo ago) was $2950

[misterdoggy]

I currently use a Ayre K5xe. The Ayre replaced a passive preamp made with the biggest stepped attenuator Shalco makes. In absolute terms the passive pre is the most 'transparent' device I've ever heard. The Ayre replaced the passive pre because I run long IC's. Long IC's and passive preamps don't work well together.

Using a step-down tranny to power a K5xe should be fine. It's a good preamp, but not $5k good. FWIW the list price when I bought my K5 (about 18mo ago) was $2950

Yeah I was thinking about the Ayre, but there aren't any on audiogon and the one here for $5000 is throwing money out the window.

Well I just closed a deal on a Pass Labs X1 refurbished with guarantee and in 230V for $2350. Its more than twice that new so I think its a good deal.

I took advice from Krellfan as he has 3 x 350MCX Krells and is using a Passlabs Preamp and is very happy with the combo.

Also I read 8 consumer reviews and all were brilliant. Using words like "warmth" etc and a couple with comparisons to Krell and using with Krell Amps so the direction has been taken. The Die is cast so to speak.

Also I was worried with getting either the Ayre or a Krell with a Step down transformer. With all the equipment I'm running to have an extra transformer is worrisome. We are all worried about interference and noise and a crude Stepdown transformer could be the source of lots of worries.

I have really short IC's 1m max so .....

I think I took the best route. I will let you know in a few weeks.