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JonEdwards

Talk to me about pre-amps please.

4 posts in this topic

So, I'm a relative newbie to the DIY hifi world.

Initially, I'd like to build myself a pre-amp to replace my Quad 34, whichI suspect is the weak link in my system (pre y2k Rega Planet, Quad 34, 2x Quad 306, PMC TB2), with the follow up being to create a pair of mono block power amps (probably Hypex UCDs) and possibly a sub.

Looking around, most of the pre-amp kits seem to be some variation on the passive theme. (would prefer to work from a kit as my electronics theory is pretty weak). My only experience of passives is an Alps Blue "pot-in-a-box" I built to sit between the Planet and the first Q306 prior to getting the Q34. It sounded kinda flat and lacked oomph, and generally I wasn't impressed. (I saw one comment the other day that equated pots/attenuators to "driving around with your handbrake on" which I felt was quite apt.

Based on that, I'm quite taken with the TVC idea. (Glasshouse ones look good). However I'm not sure whether my current kit will have the required synergy mentioned. (I think the Rega has a 2V output, the schematic I have for the 306's says 375mV input for full output. No idea about impedances)

One other possible issue is that of cable lengths. I can do a short run from the CD to pre-amp, but ideally I'd like to move the amps to the bottom of the 'speaker stands (short speaker cables = better grip??). These cable runs would then be in the 4m territory. Too much?? In an ideal world, I'd run a balanced connection (once I upgrade the amps), but that adds another layer of complexity to the setup. Can anyone recommend a simple unbalanced -> balanced buffer module and PSU?

Lastly as an aside, does anyone know if the 306s can be run bridged?

Any advice gratefully received. I'm reasonably good at the practical end of things, but quite lacking in the theory area to make decisions as to what will and won't work.

Cheers,

Jon

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Thanks for that EOS:)

Inputs are fairly straightforward. CD (95% of listening) and ipod (usually on shuffle, for background noise)

The Hypex stuff is of interest a) because all the relevant modules are available from one supplier so I know it'll all work together; b) the efficiency of class D appeals; c) the price is bearable.

Point c actually brings up one of the other reasons for interest in the DIY world. Price. Bar the CDP (now 8 years old), everything has been acquired at a significant discount. The 306's were £60 each, the 34 £120, and being a natural tightarse, I'm very reluctant to spend large wedges of cash for each small upgrade. I can justify the £350 for the Glasshouse TVC to myself. I can't really do that at higher ££age.

I'm not dead set on getting rid of the 306's by any means - they do seem to have a good rep. That said I am hankering after a chunk more grunt (hence the bridging enquiry). Following a redecoration effort in the lounge, I think the room is a lot more dead and consequently I have to run the system quite a lot louder to get the same kind of impact from the music.

Music wise I listen to all sorts - pretty much anything played by real people on real instruments (with the exception of rap and opera!!) I might well start a listening session with something fairly loud offensive and:rockin:(great smiley btw) and finish off with a string quartet or solo jazz guitar. I guess I'm used to a fairly warm sound courtesy of the quad gear, but the pmc's do have a fairly healthy bite to them, so it's by no means all warm and fuzzy.

I guess my "ideal" is the old "wire with gain" adage. I want to hear what's on the CD, not end up listeningto the amp/speakers/whatever.

I don't have a vast experince of listening to different hifikit(never heard anything valve powered) - most of my listening experiences are courtesy of concert PA systems, so I don't necessarily have the language to explain what I want. I'm also very aware that the mind is very susceptible to suggestion (see 1,000,001 cable threads!) so don't entirely trust my own judgement in such matters!

Back on topic. Valve line stages - care to recomend any? I'm aware of teh World Audio Designs one, but that's a bit expensive by the time I've added the PSU...

Thanks again!

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Hi Jon, Welcome. :)

You might be interested to have a look at my current project (New Project thread).

It started out as a DAC, but has evolved into a fully balanced pre-amp. It might help you

to get a feel for what might be involved. My method might not suit everyone, but I've

found the modular approach to be ideal for my moderate level of DIY electronic skills. ;)

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