OK - I have had a play with the ZTPRE and...

[maxg]

Refering to the manual which I downloaded on line:

"Starting from the left as youre looking at

the back, the first switch is changes the

output coupling caps from 4uf to 0.47 uf.

Both caps are poly and audiophile grade

quality. The 4uf cap (Cap A) will have

extended bass response and a slower

smoother presentation. Some amps will

puke during heavy peaks from the excessive

dynamic range offered by this cap.

The 0.47uf cap (Cap excels in speed

and accuracy to a point of revealing the

many faults of mid fi digital front ends. Its

drier presentation is often preferred with

Vinyl."

What does it mean that an amp may "puke"?

"To solve this problem, the ZTPREs output

level switch actually changes the circuit

from a conventional paralleled single

ended triode with the plates driving the

output, to a nifty little variation where the

cathodes drive the output. In the cathode

(or NORM) position, the ZTPRE actually

attenuates without compromising the signal

path with additional parts."

Huh??

Anyone? These setting changes certainly make a huge difference in the sound. I played Dire Straits "Private Investigations" last night and it didn't perform all that well until I adjusted the Bias switch to "aggressive" and the output coupling cap from 4uf to 0.47 uf. Then it just blew me (and the Accuphase) away.

Pity these switches are all mounted on the back - changing settings is going to be a real pain. It would probably have been better to put everything on the front plate and just provide a flip down cover or something to hide the wiring.

------------------

2 * Heresy 2 (mains)

2 * Homemade horn speakers (rears)

1 * REL Strata 3 sub

Accuphase E211 amp.

Tube monoblocks with separate pre-amp (DECWARE ZTPRE with separate beefed up PSU)

Marantz CD6000 player

Sony NS900 SACD/DVD player

Stax Headphones (on loan to a friend)

Humax 5400 digital satellite receiver

Sharp Video

32" Sony flat screen 16:9 TV

Mogami interconnects

Silver Synergistic speaker cable

[Randy Bey]

I am automatically suspicious of anything spawned from the fertile organics-rich mind of Steve Deckert.

His formula is 80% marketing, 15% parts, 5% design.

[mobile homeless]

The Decware ZTPRE is just about the only preamp I know that has this switching capability. It is its downfall and also its unique quality that can make it amusing. By downfall, I mean is it a bit controversial and rare to see. It actually is a much more flexible unit and is also DUAL mono with a separate power supply(also dual mono). When you are running your KT88 monoblocks, the ZTPRE will allow you to be totally dual mono to output.

You essentially have the ability to switch between two different sizes of caps which will affect the rolloff characteristics and the speed and sonic picture of the piece as well. The 4uf cap is a greater value than the .47uf selection. While your presentation might sound like it has more bottom I would think it could slow down the presentation making it sound less quick, thereby nullifying some of the speed. This has nothing to do with getting from point A to point B; I am talking about the ability for a component to sound agile and quick with good timing. With the 4uF cap, this aspect might suffer. I personally will imagine the sound to be more to your liking in the .47uf cap but there are times that you might prefer 4uf. To run these switches from the front would add long traces a wire perhaps bringin in hum as well. It's an interesting idea... It does add a gaggle of circuitry to the mix. Some amps might not do well with the 4uf connection since it does have much more extended rolloff points. You just need to experiment with which take you prefer on the whole. I am willing to bet it will be the .47uf setting but the 4uf could come in handy with some material and/or amplification. You should try both setting into your Accuphase and your KT88s to get a handle. I think you will find your Accuphase to be MUCH more to your liking as well. The fact that Deckert actually included TWO sets of coupling caps is rather notworthy. IF you followed the thread with NOS, you see me talking about some of the problems with increasing the size of coupling caps to bring more bass. IT can SLOW the unit down losing a bit of the quickness, something that I have grown to dislike. Deckert's ZTPRE allows you to compare both approaches, allowing a flexibility that you dont see.

As for the other comments, ole Steve thinks he has come upon a way to attenuate the sound without harming the dynamics. This is good for amps that are VERY sensitive at the input requiring less signal. According to Steve, running a resistor to ground divide the voltage to reduce the signal can be bad for detail. Deckert opts for the cathode output to reduce the signal for those VERY sensitive amps at input. For amps that need MORE gain, drive them with the anode switch engaged.

For the bias, this is simply a switch that provides more or less bias. More bias brings a smoother more laid back sound perhaps being more musical. The "aggressive" bias is simply backing the bias off which bring about a more incisive presentation, but also might sound less smooth and musical. Some prefer this though as it might seem to be more dynamic sounding; I have no idea how much variation there is in his settings, however. To be sure, this is ALL VERY rare in a preamp!

Again, the switching in the rear is to keep the wire to a minimum (and to avoid more cost as well).

Steve Deckert's ZTPRE preamp is definitely unique though. Some would think it is a bit controversial... IT surely is geared towards the person that believes WIRE and PARTS make a differnence. There are a LARGE portion of Klipsch Forum patriots that would be scratching their heads at the ideas within this preamp.

I think it would be a neat tool to have to compare components. It's a defacto TEST unit!

kh

------------------

Phono Linn LP-12 Vahalla / Linn Basic Plus / Sumiko Blue Point

CD Player Rega Planet

Preamp Cary Audio SLP-70 w/Phono Modified

Amplifier Welborne Labs 2A3 Moondog Monoblocks

Cable DIYCable Superlative / Twisted Cross Connect

Speaker 1977 Klipsch Cornwall I w/Alnico & Type B Crossover

system one online / alternate components / Asylum Listing f>s>

This message has been edited by mobile homeless on 03-05-2002 at 08:52 AM

[arco]

Thanks both Mobile and Mdneen,

As the former owner-modifier of this design, I could not have said it more extensively!

Just one comment: I have very quickly discovered that this 4uF output capacitor selection was kind of a joke. The only think it did was to "muddy" things up. From previous experience, I know that each and every preamplifier circuit favours a particular value of output cap and, this, regardless of the power amp that it drives. With an AUDIO NOTE M7, for example, I know that the problems begin to get serious if you go past 0.22uF (Manufacturer's spec. and best choice: 0.1 uF).

To cut a long story short, I stripped out the 4uF caps (the other ones, as well...) and - after experimentation - I chose to use 0.47uF VTV silver caps as my main choice (in and Hovlands of the same value in position A (very nice for rock-electric jazz).

So, dear Max, the differences you are hearing have only to do with the different sonic characteristics of the output caps, not their different values.

Aristidis

www.aca.gr/pop_coumpas.htm

[maxg]

Thanks Arco - you had said you had made changes but I did not realise that you had removed the 4 uf cap altogether and replaced it.

Thus far I also prefer the "b" selection - "a" seems to be somewhat darker and a bit more ponderous. Maybe that is its signature but I think it is not for me.

I am currently evaluating the Aggressive/normal bias switch and tonight plan to test agressive with classical music - I certainly prefer it with Rock as I said above. I certainly dont want to make the sound of the classical too hard, but, on the other hand on the normal setting it seems a touch too sweet for my liking after prolonged listening (4 hours last night).

Some pieces respond particularly well to this sweetness (especially the Grieg and the Straus Waltz's which are simply sublime) whilst others suffer a little at the lack of attack (the Rach 3 is a bit subdued as is Beethoven's 3rd Symphony).

To be honest this is my main concern for my future amp developments as well. I have heard that the triode amps lack the attack I like - even for classical. I am so kean to test your set up in this regard.

I am really hoping I can alite on one setting for all my music (probably optimistic) because getting up and fumbling around the back for the right switch is already getting to be a bit of a pain.

So far the biggest beneficiary has been the soundstage - it has gained depth and height (although the latter may be a result of the re-aligned speakers as well).

I have still not got around to testing vocals at all - so much to do - so little time!!

[maxg]

Ya know - call it prescience if you will but I have the strange feeling me old mate Mobile is replying here about now.

This "who is logged in feature" is really cool - it shows you what people are doing too...

Hi Mobile!!

[mobile homeless]

Let me get this straight. I LOVE this. I get so much FLACK for my love of oil caps. Arco, are you saying you have the oil caps in which switch position? That is exactly as how I would use those caps choices. I would find the best values with my amp choice and sub a quality copper foil oil in one position and a good teflon or film/foil in the other. The oil caps do VERY well in SET amplifiers but they DO bother some with the slightly less pronounced transiant response. That is why you have to have the rest of your system totally up to snuff. Also, you have to discover which sounds more natural. In this instance, it is really good to have both. The oils have an amazing naturalness to the sound.

By the way, to clarify, I have not called caps FAST OR SLOW per say; I said the presentation and resulting sound from the use of caps that are TOO large a value, when mated with certain amplifiers etc, could hamper the quickness of the overall presentation. The cap is not "fast" or "slow" in this situation. On the other hand, some caps can sound quicker with more transiant snap. Caps DO have different sonic presentations. Teflon and certain film/foil caps sound just a bit quicker than the modern oils; I just dont think their sound is as good overall.

Triode amplifiers DO have attack. What you might be talking about is biasing a push pull amp to high. Then the sound does become rather soft and fuzzy....almost TOO sweet. Who knows what settings ole goonball Deckert is using. On the other hand, pure triode wired amps using a dirctly heated triode such as the 2A3 (just for an example), have amazing, almost startling attack. I think the 2A3 has the most jump factor of any tube I have auditioned and is more so than the 300B. I was listening to some Stravinsky yesterday morning from the other room and one his well knowns dyanmics shifts actually scared the bejesus out of me!!! Literally, my heart was racing. A good SET 2A3 on horns has an amazing sense of attack surely more pronounced than any other amp I have had.

kh

This message has been edited by mobile homeless on 03-06-2002 at 08:51 AM

[arco]

Couldn't agree more with you Mobile...

1) Discussing capacitors and the like (even amps!), we tend sometimes to disregard the fact that each and every choice is finally made in the context of a system (room included). I personally love good paper in oils but too much of a good thing is...too much. So, if I use PIO's in my tube amps I try to give them this little "political correctness" they need by using more conventional types in my crossovers and so on. As this is always done within a specific system (notwithstanding personal preferences...), I very well understand that the mileage of other people may vary. I quite preferred the hovland, for example, when driving transistors. But then, I am a person who quite likes oriental sweets, but drinks his coffee sugarless!

Subsequently, ole Max (as you use to say!) could eventually take a soldering iron and a bunch of capacitors and experiment to his heart's content, until he finds his own personal bliss. And, as usual, luck always tend to smile to the adventurous!

2) The system must always be "up to snuff". This - according to my reading of the expression - has mainly to do with the achievement of the basic synergies between the components and also with the room. In a different siyuation, why bother with fine tuning issues such as capacitor choices?

3) Those who say that tube SE amps lack frequency extension, dynamics, attack etc usually fall - according to my book - into 2 categories: The first one is populated by people who just repeat "things they heard". They never put it that way, but if you try to discuss the issue with them, you quickly understand that they do not even know how an OPT looks like. The second category gathers all those people (and they are many...) who have never heard these amps drive the kind of loads, for which they were designed for. Example: I once tried to drive a pair of AERIAL 10T's with an AUDIO NOTE MEISHU (300B SE, 9w/ch). The amp drove the beasts to nice levels, the mids were gorgeous but it just couldn't "wake them up" dynamically. If this was my one and only experience, I would be myself a convinced and cheerful power advocate.

4)Tomorrow (unless a force majeure situation arises...) our friend Max will have a taste of his specified valves, horns & vinyl concoction. Let's see what he thinks.

Aristidis

www.aca.gr/pop_coumpas.htm

This message has been edited by arco on 03-06-2002 at 12:34 PM

[maxg]

Unless I get horrible lost I should be there by 6 pm and we will see what we will see (or is that hear?).

I am very much in Arco's category of someone who has not heard single ended troide amps but has heard from others that they lack the attack that I believe I need. Arco seems confident they do not and I am sure he is right - we are well outside my area of knowledge in this aspect.

The good news in on the VTPRE front. I have found the setting combo that I like and it is with the Agressive setting (less bias) and the original 0.47 Mf cap fitted on option B.

I had first Beethoven and then Rachmaninov let rip last night till the wee hours and it was wonderful stuff. This is a huge relief for me - I was genuinely thinking of going back to my old SS pre-amp if this test failed whilst I started this whole cap swapping exercise.

AS it is I am delighted with the sound as I have it now and am likely to stay that way till at least 6:30...

Just never stops this hobby of ours does it.

[dubai2000]

maxg,

no, fortunately(?) this hobby never stops, because once you have come close to your 'ideal' combo, there is so much music out there that is just waiting to be discovered. The beauty of a proper Horn/SET combo is in my ears (eyes) the fact that one suddenly listens to music that with different systems once might have ignored. Myself I used mainly (about 95% or so) to listen to classical music and while classical is still dominat in this house, I am also discovering the joys of jazz (Brubeck, M.Davis, P. Barber, H. Cole, C. Wilson etc), what we call world music and even my old pop LPs. I even picked up a set of Rrank Sinatra's greatest hits, and that really improves my mood in these rainy and cold March days. So even if one has found the right combo, this is only 'the beginning of a wonderful friendship'

Wolfram

...and don't think there'll be a way back from a Horns/SET combo!!!

------------------

Khorns, tubes and a suitable room: Welcome to aural paradise!

System:

1973 Khorns with ALK crossovers

REL Stadium II sub

Cayin 743 D integrated tube amp

McIntosh MR 77

McIntosh MCD 7007

Thorens 520S

SME 3012-R

Ortofon SPU Classic GM E

Cyrus aEQ 7 phono stage with PSX-R power supply

Alternative system:

Quad ESL 63

McIntosh MC 2105

McIntosh C29