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Old 28th December 2003, 04:49 PM   #1
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Default beginner amp choice question

Hello all!!! Hope everyone had a good Christamas!!

This is a bit of a general question, but hopefull;y a bit more specific than most...

My room is 11ftx11ftx8ft tall, speakers spaced 6ft
My speakers are B&W DM309, which arent on the website for some reason, but theyre basically floorstanding versions of the DM303, but 2.5way with an extra bass driver.
Sensitivity of these should be around 88dB 2.83v 1m (apparently... if theyre similar to the bookshelves, which the 600 series speakers all seem to be)
Im currently running a Rotel RCD-02 (soon to be modded with better clock and op-amps) into a Rotel RA-01 integrated amp.

The main types of music i really sit down and listen to properly are modern art/prog rock (such as tool and a perfect circle, incidentaly, tools 'lateralus' album has to be the best hdcd recording weve found yet) and occasional bits of trip-hop like the sneaker pimps and massive attack etc. Other than that it mainly gets used for background music with pretty much everything, from punk to classical

Im thinking about trying the WAD KaT6550 running off the RA-01's preouts. How do you all think 40wpc ss power will compare to 40wpc valve power/sound? I quite fancy this amp, especially as it's British made so there's no hassle trying to get one into the country. Also does anyone have any ideas for modifying and improving this amp in the future, like any ways of optimising the circuit for kt88's, or wether kt88's would be better than 6550's at all.

Main question I guess would be am I likely to be happy with the power and bass response of this amp? I'm just put off slightly by tubes name for being a bit weedy down the bottom end. Anything better than my current amps bottom end i would be happy with, and i guess the mid and top end would be vastly better.

Thanks everyone in advance for any help!!!
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Old 28th December 2003, 08:28 PM   #2
SHiFTY is offline SHiFTY  New Zealand
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Looks pretty grunty, should be able to drive your speakers with ease. Well designed PP amps usually have a decent bottom end, should be just fine. The (ultralinear) output transformers look pretty large, but its hard to tell if they are any good... you might want to ask them what they are, given that they are the most important part of a valve amp.

Only dislike of mine is the driver tube, I would have done it differently, given a bit more drive to the output tubes. But it will work fine and be a fun project if you DIY. Good thing is that new old stock Mullard ECF80 and NOS 5U4s are still available cheaply.

Be warned, valve amps are addictive, you will soon get involved in debates over the most inane topics, such as which capacitors are more musical and SET vs PP ad infinitum

Go for it.
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Old 28th December 2003, 11:57 PM   #3
dhaen is offline dhaen  Europe
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I have built one of those amps for someone. I used it for a couple of days and was impressed. It sounds typical of amps using that topology, although it overloads more gracefully than some.
The output transformers are very meaty! They are pretty good at the bottom end. All the wound components seem to be of far eastern origin, but that is what makes it affordable.
The finish of the chassis was very good. The chrome plating on the transformer covers was not up to the same standards. The grub screws were missing from the knobs. (This was the integrated version). Make sure to tally all the parts before construction.

I would summarise that it's very good value for money.
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Old 29th December 2003, 05:40 PM   #4
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Thanks all!! That's put my mind to rest quite a lot now.

I would be quite happy to get addicted to DIY valve amps!! Far too many things to explore and try out! Does anyone wind their own transformers any more? I remember my grandad used to, but no one on these forums seems to. Also, is there any good reason why toroidal transformers aren't used that much? or is that going to be the next progression...

I'm also a machinist, so merhaps i could mill up some transformer caps out of solid alloy or something? That shouldn't interfier too much with the operation of the transformers should it?

Another question.... My speakers are wired so that one set of connections runs mid and bass, and the other set runs just the tweeters. Would it be a good idea to eventually run the WAD amp on mid and bass, and build some 300b SE jobbie on the tweeters? Or would that be a bit of a waste?

Thanks again
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Old 29th December 2003, 08:22 PM   #5
dhaen is offline dhaen  Europe
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Wink Walk before you run...

Yes, there are a few who have wound output transformers, but it is not trivial.

Toroids are available, but less popular.

I'm not sure of the best material for transformer end caps (bells).

Bi-wiring, and bi-amping are all possible in the valve world. Some do, some don't.

The 300B in SE is particularly nice in the mids IMO. I think it would be a waste to use one for tweeters only.

There is a wealth of information on the forum. Learn to use the "search" facility to your advantage. Note that results can be shown as threads or posts. I find the latter most useful, but the former is the default setting.
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