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-   -   is it best to have an outbaord pre with t-amp (http://www.diyaudio.com/forums/class-d/66391-best-have-outbaord-pre-t-amp.html)

gilbodavid 21st October 2005 01:19 AM

is it best to have an outbaord pre with t-amp
 
is it best to have an outboard pre? i'm going to mod a t-amp in a box which already has a stepped attenuator volume control, and have bought an elma switch to put in there with 5 imputs, as an integrated amp. am thinking of then buying a charlize and doing the same. have i missed the boat on seperate pres being better? Thanks

sx881663 21st October 2005 03:08 AM

To pre or not to pre, that is the question
 
I am sure that there will be a lot of controversy in this thread as everyone will have their own opinion.
What is the need for a separate preamp? Not enough back panel space for all the input/output jacks? Circuitry so complex it needs its own box just to hold all the parts and power supply? Need an RIAA stage and donít want a separate box? Just need a lot of in/out connections and a lot of switching? Need some special circuits that it wouldnít make sense to have anywhere else? This could be like active crossover circuits or digital correction circuits or whatever.
Some of these cases are good and substantial reasons to have a separate pre but if you donít have these special needs it makes much more sense to have it all in one box to eliminate a lot of stuff from the signal path including 2 pair of chassis jacks and an interconnect cable pair. Anytime you can shorten and simplify the signal path there are sonic benefits to be had. If less available gain is a problem the amp input circuit can be tweaked to handle it. These class D amps are so quiet that increasing the gain is not a problem. This solution not only is the best sonically but is substantially cheaper as well.
Of course it donít look as impressive if this is important to you.
Roger

Nuuk 21st October 2005 12:42 PM

Well, I'll nail my colours to the mast and say that the class-T's need an active stage feeding them!

I'm not sure if that is what is being asked here, or if it is more a question of buffer (same box) or pre-amp (separate box). I've gone for a separate pre-amp but only because I find myself reviewing different items and I need that modular approach!

If I was building for sound quality, I would put the buffer that I have in the pre-amp, into the same case as the Charlize (for example) and remove either the output capacitors on the buffer, or the input capacitors on the power amp!

And of course doing away with another set of interconnects and sockets can't be a bad thing! :att'n:

Bgt 21st October 2005 03:07 PM

Quote:

Originally posted by Nuuk
Well, I'll nail my colours to the mast
what does this mean?

Nuuk 21st October 2005 04:50 PM

Quote:

what does this mean?
Oops, sorry, I forgot that I am on an international forum. You all speak such good English, it is easy to forget!

It means saying what you think and making it public so that you cannot retract it later. I think that it originates from the days when armies would have colours (flags/uniforms) and people would align themselves to one side or another by choosing the same colours. Nailing them to the mast meant that others could see which side you were aligned to. ;)

KT 21st October 2005 05:47 PM

Nick,

I recalled in your review or elsewhere that the SS linestage you used maybe veiled things too much and that the D-class amps were preferable running without an active pre. Has your opinion changed after further listening?

I built my Charlize without a volume control with the thought of using an outboard tube pre or an outboard attenuator. I'm running it with the tube pre right now, so I haven't heard the Charlize with only the attenuator.

No firm conclusions yet, though. Right now I'm trying to get the tonal character of my tube pre to my liking and, boy, do changing out the coupling caps make a huge difference. I'm not sure if I've found a combo that I like, yet.

I do agree, however, that the Gaincard can benefit from a tube pre. Maybe the class-D, too?

Happy listening.

KT

Nuuk 21st October 2005 06:03 PM

Quote:

I recalled in your review or elsewhere that the SS linestage you used maybe veiled things too much and that the D-class amps were preferable running without an active pre. Has your opinion changed after further listening?
KT, ou are correct. During the class-T amp review, I briefly tried a couple of solid state pre-amps but didn't feel that the I preferred the sound using them. However, I am now using 25K volume controls because the two NOS DACs that I have here work much better into the higher load.

But using the 25K volume controls doesn't suit the class-T amps and I have found it better to use an active pre-amp. However, I am using the 'Les Sage' class A buffer, rather than the opamp buffers that I tried before!

So to sum up, what I reported in the review was based on my experience using a 10K attenuator in my second system (no NOS DAC). What I am saying in this thread is based on using the class-T amps with a NOS DAC in my main system! :att'n:

But I would urge anybody using a class-T to try an active pre-amp or buffer and see (or hear) the difference for themselves. I suspect that it is no co-incidence that a couple of the class-T suppliers are planning on offering matching valve pre-amps (or buffers) as well! ;)

kanaddict 22nd October 2005 02:42 AM

Quote:

Originally posted by Nuuk
I suspect that it is no co-incidence that a couple of the class-T suppliers are planning on offering matching valve pre-amps (or buffers) as well! ;)

Nuuk,

take a look at the autocostruire new kit !

http://www.autocostruire.com/catalog...roducts_id=267

and

http://www.autocostruire.com/catalog...roducts_id=266

Look interesting for those who want to take the tubes rode !

Regards,

KT 22nd October 2005 06:37 AM

Nick,

I am doing a similar thing, but with a tube pre: Monica II ---> Cary SLP-94 ---> Charlize. The results are very promising.

The Monica II and Charlize are run on SLAs. I have yet to try the SMPS, which I understand improves the performance.

Those Autoconstruire tube hybrid kits look interesting.

Best,
KT

MrDodo 22nd October 2005 07:07 AM

Integrated tube T-amp looks expensive too.


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