FS - Pre-amp with output Transformers

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vinylnvalves
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FS - Pre-amp with output Transformers

Post by vinylnvalves » Sat Oct 28, 2017 7:00 pm

I am having a clear out and as I am committed to a DSP driven system, I have no use for my valve pre-amp. Being lazy follow the link to the advert on DIYA.

http://www.diyaudio.com/forums/swap-mee ... e-amp.html

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Paul Barker
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Re: FS - Pre-amp with output Transformers

Post by Paul Barker » Sat Oct 28, 2017 7:21 pm

Shame your lazy because I cant open the jpegs on your link without joining.
I can do it right or I can do it now, but I can't do it right now.

vinylnvalves
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Re: FS - Pre-amp with output Transformers

Post by vinylnvalves » Sat Oct 28, 2017 7:53 pm

Lazy, was an excuse for my ignorance of being able to make the pictures I took on my iPad smaller in size so I can post them on the forum.

vinylnvalves
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Re: FS - Pre-amp with output Transformers

Post by vinylnvalves » Sat Oct 28, 2017 8:10 pm

Sorted it so here's the full advert..... can only seem to post 3 pictures though

Up for sale is a preamp based on the design of troels gravesen, see link TRAM w.
Reason for sale is I have moved to a fully active system now using a DSP so this preamp is redundant and has been sitting in the cupboard. It had a very typical with output transformers sound, used with some 6B4G amps feeding very efficient horns - low background noise, even when feeding 114db efficient speakers.
My version is based arround Bartolucci output transformers. I used a solid state HT power supply with regulation via a Salas Shunt board. The volume control is via a 30 increment stepped attenuators, around a shallco style switch, to with the resistors are directly soldered to it.
I used kiwame resistors, a obligato film capacitor and silver mica resistors in the circuit along with the 2 watch batteries per channel.
It is built on two chassis's keeping the PSU separated connected via a multi pin military connector, the psu is in a metal chassis. The preamp was built to show, with a stainless steel chassis to which all is bolted, in an oak plinth. As well as the transformers and teflon valve sockets, there is a copper plate, verdigris finish (attached to as focused heat sink for shunt regulator) On the front are two knobs ( industrial looking - can be easily changed to match you style) for volume control and input selection - currently wired for two inputs, holes for a third pair of rca's is provided on the back. All the rca's used are silver plated CMC ones. Two additional redundant holes in front panel, (easily covered by a plaque etc).

It is in full working order and its sound will make you forget about it's looks industrial looks. Comes with a number of 6n6p valves, you and mix and match the best pair from them. One picture shows the circuit I used, not including the valve power supply, a total of 2 resistors and 2 capacitors in the signal path.

My price is based around the cost of the transformers and the volume control. £400
IMG_189.jpg
IMG_190.jpg
IMG_191.jpg
This is a heavy amp, due to having 4 transformers. The preamp weights 10kg and the psu weights 5 kg. Postage will be at cost.

vinylnvalves
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Re: FS - Pre-amp with output Transformers

Post by vinylnvalves » Sun Dec 10, 2017 5:26 pm

Sold elsewhere, gone to China

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