Lampizated my 7510

[snip]

So I finally got around to finishing my lampizator and attaching it to my 7510

My 7510 has been fully modded pt.21 and 22, with a linear PSU and WIMA box caps/47u Green Nichicon BP MUSE input and output coupling caps.

I routed the signal out on the input side of the opamp stage before the decoupling caps to a couple of Neutrik RCA's in the holes where the volume control and headphone jack used to be (I have completely removed the headphone circuit and variable output circuit)

The lampizator is constructed with Russian military grade 6n6pI valves, NOS Jensen metalized film caps and standard MFR's, the HT supply is nothing special, a couple of small encapsulated transformers back to back with a CRC filter using cheap BC capacitors. The heaters are run off the same 8A regulated linear supply as the DAC, this is set to 12.6V.

I can only say, as inherrently 'wrong' as the lampizator SSRP circuit is, it blows the opamp stage out of the water good and proper.

Amplification is an Audiotailor jade OTL headphone amplifier rocking Michaelson Audio ECC83 VAS and vintage RCA 6SN7G output valve, transducers are Sennheiser HD600's with stock cable, digital sources is my Mac Pro and SB classic.

The soundstage seems much wider, the mids and highs more airy and the bass, well the bass is the only criticism I can offer, it is a little less controlled but much warmer and 'sweet' which suits me just fine.

I took a couple of pictures with my iPhone, the case for the lampizator is a temporary one, from an old digibox, I will eventually build a proper case which will also contain the linear low voltage supply and likely a redesigned choke filtered HT supply.

So anyone curious about trying the lampizator I can only say DO IT, it really is not a bad buffer.

//Jan

[James G]

That is one of the coolest ideas I have ever seen and definitely an original.

[HighFidelityGuy]

Nicely done! I've been toying with the idea of replacing the output stage of my Caiman DAC with a tube buffer stage but I've not got round to looking into it yet. It's certainly something I'd like to try to see what difference it makes.

[snip]

Nicely done! I've been toying with the idea of replacing the output stage of my Caiman DAC with a tube buffer stage but I've not got round to looking into it yet. It's certainly something I'd like to try to see what difference it makes.

Well I cannot get over how much of a difference it makes!, I took it round to a friends house the other day who has some speakers and an amp of mine since I currently have no room for such things.

Amp is two 4 channel Tripath based boards with two 26V linear supplies featuring 6 12000uF caps in a straight C filter each. These amplifiers are very 'neutral' having next to no sound signature of their own, they output about 60W per channel into two 8 inch bass drivers and a 6.5 inch midrange and 4 inch and 1 inch high, actively filtered using an opamp based filter that is pretty close to phase coherrent and also fairly neutral.

He also has a 7510 with the same modifications to the opamp output stage as mine, and the difference was HUGE, after listening to the tube buffer the opamp stage just seems soulless in comparison, for the comparison purpose we took the output from the DAC straight into the power amp, using digital volume limiting in his SB duet. normally he employs a valve based preamp.

I have now mounted my low voltage regulator board on top of the temporary casing, which is getting more and more permanent and have in an attempt to make it less messy put the upper part of an identical case over the 7510 and stacked the two boxes.

I was thinking of trying to get hold of an empty 75 series DAC case and putting the circuitry in there if I can get it to fit, it should be possible since the high current transformer for the low voltage supply is an external power brick.

Anyone have a broken 75 series or an empty case no longer needed they would be willing to part with for minor monetary compensation?

By the way I have plenty of these valves if anyone fancies having a go at constructing one of these monstrosities. Might even have a few sockets spare as well..

//Jan

[Puffin]

Snip. I have a tube buffer which is placed between CD player and amp. Can this be used in the sam way as the Lampizator. below is a link to a kit which is similar to what I have.

http://cgi.ebay.com/New-Tube-buffer-...item1c0d099eff

[snip]

Snip. I have a tube buffer which is placed between CD player and amp. Can this be used in the sam way as the Lampizator. below is a link to a kit which is similar to what I have.

http://cgi.ebay.com/New-Tube-buffer-...item1c0d099eff

Yes I see no reason that would not work, did it really come with those Elna and Wima caps? if so that is a really good price.

It's not the same kind of valve, that one is operating at a much lower voltage, how does that kit sound?

As I said I took the signal out from the input pin of the coupling capacitors facing the opamp output stage in the DAC, if you as I have modified this area of the board you will in all likelyhood have a bit of pin from the capacitors above the board on the component level where you can easily attach a wire, if not you would need to do it on the bottom of the board, or I believe there is also an SMD resistor in series with the DAC chip output pin where you could attach it, bear in mind that soldering a wire on to an SMD resistor is somewhat difficult. Under no circumstances should you attempt to attach a wire straight onto the DAC chip!

Ground is easily obtained by the RCA output pins.

As you may not want to remove the headphone socket and volume control I would suggest you drill a couple of holes between the power socket and variable output sockets and route two thin shielded wires in through there.

If after listening to both the opamp stage and your new tube buffer stage you decide you want to use the tube stage permanently you could just remove the in and output coupling capacitors from the opamp stage and then jumper across the input pin to the output pin, you would then have the non variable output jacks going straight to the DAC output chip.

There is nothing as such wrong with having both the opamp stage and a tube buffer connected to the output pins of the DAC chip as both are high impedance but in theory it should be best to eventually disconnect the one you will not be using.

I plan on implementing, if it will fit, a dpdt switch in one of the holes where the variable output jacks used to be (the Neutrik RCA jacks did not fit in there, they would have pushed the output coupling electrolytes and the box capacitors around the opamp) and lifting the pin facing towards the dac chip of the input capacitors, connecting that and the wires for the forward jacks to the switch so I can connect one or the other without having to open the box, this will be useful if I ever take the dac somewhere else where lugging the lampizator around with it might not be appropriate.

But as I said, attaching the tube buffer is fairly straight forward and easily reversable (you could just take the lid off whilst trying it out, no need to drill holes) So give it a go!

I'll be very interested to hear how it works, my friend who has my amp and speakers was most impressed and wants a tube buffer for his DAC now, but he is scared of high voltages

//Jan

[Puffin]

Snip. Thanks for all your advice. I will give it a go and see how it turns out. The buffer works at 12v so no dangerous voltages!

Rob.

[snip]

Snip. Thanks for all your advice. I will give it a go and see how it turns out. The buffer works at 12v so no dangerous voltages!

Rob.

Yes I know it is low voltage 6H23N is a low voltage valve

I am most interested in this kit, did you get a schematic with it? And did it really come with Elna and Wima capacitors?

Also, I don't mean to induce upgradeitis in you here, but 6H23 is not really the best valve in the world, the 6N6 I used in my lampi is more of an exception than the norm for Russian valves, you could try swapping them out for some nice Vintage Brimar ECC88's, I bet that would give you a bit of an Eargasm - Langrex sells these for something like £7.50 a piece, I'd send you a pair to try but I only have one of them left that is not currently in service.

//Jan

[Puffin]

below is a link to a kit which is similar to what I have.

I don't have one of those, but I have the original on which that kit is based, an MF X-10D. This uses EC88's

[snip]

I don't have one of those, but I have the original on which that kit is based, an MF X-10D. This uses EC88's

Ah, right yes you did say 'similar'

I really wonder if they do include those 8 Elna caps and the Wima's in the kit.
If so, one would be hard pressed to populate the bare board (available from Jims audio) with similar quality devices for less than the asking price of that kit.
Chances are they are fakes though.

Does the original MF circuit also employ a voltage doubler? I find it rather odd indeed that they use that rather than feeding the circuit 24V in the first place, perhaps the heaters are run in series on the 12V feed and then doubled.

//Jan