2. amps-preamps
  3. 152291-20132

Integrated amp for Thiel 3.7's

I am sort off picking up where Thieliste, Jafant and others left off in the discussion thread about what electronics to use drive the Thiels.  I was, and I suppose still am looking for a preamp to drive my pass labs 60.5 mono's, but in reading some of the posts I have also started considering simplifying my system and just going for a high end integrated.  Part of the reason I am thinking about going in this new direction is that we may be moving- and this might be the right time to scale down.

I am not sure yet, but I have started thinking about it. 
For preamplifiers I keep on toying with the idea of a PS audio BHK, Pass labs xp12, Simaudio 740p, or an Aesthetix Calypso Eclipse.  One of these would replace my Prima Luna Dialogue Premium- as I have mentioned before I think I can probably get better detail, definition, and depth a preamp with a higher quality volume control (vs the Prima Luna blue velvet).

But maybe a high end integrated might actually do the trick as well- I cannot afford one of the new Uber integrateds but maybe some high quality used ones might work.  I am budgeting under usd10k.  By selling my other equipment I should be able to get to my budget with a relatively small additional investment (usd1-3k ?).

So I have been looking at Luxman 509x, Nelson Pass Int 250, Vitus RI-100 or RI-101....Diablo 300 would be out of my reach even used but maybe the 120, and maybe an ASR (the exclusive 2 would be so many boxes that it would defeat the whole purpose of consolidating the system- so maybe the 1?).  On these last 2 I really have no idea about how much one gives up going with the lower models.

Ultimately my hope is that the list above will still get me further than where I am with my current set up.

Anyway, would be very interested in your thoughts as I look at this new angle for my system.
pgastone
georgehifi's avatar
georgehifi
10,312 posts
 
Hi @georgehifi : I have barely seen any amps mention the power rating at 2 Ohms.
Yes many Mosfets and Class-D can double from 8ohm to 4ohm, but **** themselves severely into 2ohms, and either can’t increase at all from the 4ohm figure or actually go backwards, or worse still, blow or shut down.
Oh and forget about tubes altogether trying to do this.

They typically say something like “... stable at 2 Ohms”
Yes that’s a bit of a smoke screen, as even a 30w 1980’s NAD 32020 integrated is stable into 2ohms, just means it won’t oscillate or blow up, doesn’t mean at all that it can drive a speaker that’s 2ohms.

Cheers George
imhififan's avatar
imhififan
2,212 posts
 
How about the Coda CSiB integrated:
Preamplifier section is built on the Burr Brown PGA2310. It controls an analog attenuator with 99 steps with precision resistors. The balanced input is organized without OP amps - the signal from the XLR connectors passes through a buffer with discrete transistors. All switching is built on miniature relays.
Power amplifier section using Precision Bias system originally developed for their Ts power amplifier, with discrete JFET differential input stage, VMOSFET voltage gain DC coupled to an ultra wide band bipolar output stage. Each channel has eight pairs of 230-watt bipolar MJL4281A / MJL4302A and two pairs of ThermalTrak NJL3281D / NJL1302D, In total of 20 output transistors in each channel.
Power supply is a 3kVA transformer with 80,000uF filter caps, capable of delivering 400 watts at 8 ohms and 800 watts at 4 ohms per channel and up to 8W operates in class A!
georgehifi's avatar
georgehifi
10,312 posts
 
How about the Coda CSiB integrated:
This should work nicely, even though they don’t give the 2ohm wattage figure, 20 x bi-polars per channel, if the power supplies up to it it should give it a higher wattage figure into 2ohms, than it does into 4ohms.

Cheers George
pgastone OP
79 posts
 
Hmm thanks for that- definitely interesting.

Btw, anybody have thoughts on the Nelson integrated (250)...reviews are good and I obviously have some familiarity with the Pass sound that works well with the Thiels.
I obviously have to wonder how the INT250 would compare to mono 60.5's with the Prima Luna preamp....I would suspect that for the INT250 to be an upgrade the preamp section would be key.
georgehifi's avatar
georgehifi
10,312 posts
 
Btw, anybody have thoughts on the Nelson integrated (250)

Generally push/pull complimentary Mosfets aren’t too good at doubling wattage and supplying current down into that broad band of 2ohms, I stick with and look for BJT (bi-polar) amps. Maybe the Coda above?
Cheers George
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