C.H. Diamond 6SN7 Tube Preamp

Clipdat

Check out this awesome looking tube preamp that I just came across on eBay: https://www.ebay.com/itm/C-H-Diamond-6SN7-Tube-Preamp-Khozmo-Attenuator-Goldpoint-selector-switch/272887717384

"C.H. Diamond 6SN7 Tube Preamp"





The description sounds like this thing is no joke:

"The circuit is all direct coupled from the first tube to the last. The only coupling capacitor is at the output, where having one is unavoidable.
For that, I chose an Audyn True Copper Max.
The Max version is only available directly from the manufacturer in Germany at this time, but given the high rating it received from humble homemade hifi, I had to try it.
It took quite a while to arrive, but was well worth the wait. This is by far the best sounding capacitor I've heard.

The attenuator is a Khozmo series 100K.
This is an exceptional volume control, with 48 steps, which gives plenty of fine adjustment (1 db per step at the lower end), and an outstanding sound.

The signal path wiring is all solid OCC copper.

The power supply begins with a hexfred rectifier, choke filtered, then branches off to separate filter sections for each channel (to reduce crosstalk), ending with the last two filter sections using Solen film caps.
They took up a lot of room in the chassis, but I think they improve the sound over electrolytics in that critical final filter section which interacts with the signal path. No electrolytic, no matter how nice, will ever sound as good as a film cap."

@tonyb @pitdogg2 @kharp1 @mikeyb128 @mhardy6647 - What say you?

pitdogg2

All I can say is I'd find a way to get those Solen's gone.....
I see you can buy with out the EH tubes. I'm not a big fan of those

Clipdat

Get those Solens gone? What do you mean?

pitdogg2 wrote: »

All I can say is I'd find a way to get those Solen's gone.....
I see you can buy with out the EH tubes. I'm not a big fan of those

mikeyb128

I’m sure it doesn’t sound too bad. It’s a little
Pricey in my opinion. You could get something tried and true on the used market for much less. Like that joule lurking in the FS section.

Clipdat

Thanks for your thoughts!

I think you meant the Modwright, the Joule is sold.

mikeyb128 wrote: »

I’m sure it doesn’t sound too bad. It’s a little
Pricey in my opinion. You could get something tried and true on the used market for much less. Like that joule lurking in the FS section.

mhardy6647

FYI and FWIW, this is a (another?) nice option in a cost-effective, 6SN7-based preamplifier.

http://www.tubes4hifi.com/pre11.htm (the "SP-14" kit).





PS I'd agree about the Solens -- kind of 'entry level' decent-quality capacitors. Such a circuit deserves better. The cost differential doesn't have to be huge, either (Solens are pretty inexpensive and not the best sounding).

pitdogg2

mhardy6647 wrote: »

PS I'd agree about the Solens -- kind of 'entry level' decent-quality capacitors. Such a circuit deserves better. The cost differential doesn't have to be huge, either (Solens are pretty inexpensive and not the best sounding).

This^^^ Solens just hurt my ears. They're much better caps that are MUCH better sounding that do not cost but just a little more.

Clipdat

That looks sweet! I want it!

Clipdat

I guess that's a strange design decision then by the maker of that preamp. Curious as to why he would go that route if there are improvements for a minimal price increase.

pitdogg2 wrote: »

This^^^ Solens just hurt my ears. They're much better caps that are MUCH better sounding that do not cost but just a little more.

mhardy6647

I am somewhat late to the party, but I've become something of a fan of the 6SN7 and (more to the point) its forebears in the last couple of years.

http://vinylsavor.blogspot.com/2014/02/tube-of-month-6sn7.html



http://www.effectrode.com/signal-tubes/the-6sn7gt-the-best-general-purpose-dual-triode/
http://www.fourwater.com/files/hist6sn7.txt

mikeyb128

Bang for the buck comes to mind with 6SN7’s

Clipdat

Another cool eBay find: https://www.ebay.com/itm/PM-Audio-PM-201-6SN7-linestage-preamplifier/152950427522

"PM Audio PM-201 6SN7 linestage preamplifier"

mhardy6647

Looks like that one has better coupling capacitors in it

Are those 7N7s in socket adaptors?

Clipdat

Yep! From the auction description: "Also included is a pair of 7N7 to 6SN7 tube adapter along with a pair of Raytheon 7N7"

mhardy6647 wrote: »

Are those 7N7s in socket adaptors?

mhardy6647

There was a time that the 7N7 was the cheap NOS option for 6SN7s, but
1) I think virtually all (if not all) Loktal tubes (and, thus, 7N7s) were made by one manufacturer (Philco, if memory serves). In other words, the tube rollers won't really have a lot of options in "7N7 space"

and

2) The secret got out pretty quick, and consequently the hyper-cheap 7N7 supply dried up pretty quick.

Clipdat

I don't know why but I want to try different preamps. Ideally I would have several that I could cycle through depending on my current mood/taste.

I need serious professional help.

mikeyb128

Buy one good preamp that has some resale. That way you can sell it to try others. My Cary lasted 2 years, and has to be a personal record of mine.

Clipdat

But that's the thing, I don't want to sell them. I want to keep them.

mikeyb128 wrote: »

Buy one good preamp that has some resale. That way you can sell it to try others. My Cary lasted 2 years, and has to be a personal record of mine.

mhardy6647

Have you seen a picture of my house?

... and I avoid collecting preamps because I've heard so few that I actively (pun intended) liked (and that I can reasonably afford)!

Jstas

I only have 2 pre-amps. Unloaded anything else I had.

I have an Adcom GFP-750 "blue board" that I picked up from someone here and an Onkyo P-301 which is way better than anything that inexpensive has any right to be.

Neither are super high-end but the Oinker serves to impress every time and that Adcom can stand toe to toe with anything at any price point and hold it's own. I love both of them and have had no desire to replace either one.

Clipdat

That Adcom has been on my radar for a while, would love to give it a try!

kharp1

If it doesn't have a 2nd set of pre outs its destined for the scrap heap.

Clipdat

No sub out?

kharp1 wrote: »

If it doesn't have a 2nd set of pre outs its destined for the scrap heap.

kharp1

Clipdat wrote: »

No sub out?

kharp1 wrote: »

If it doesn't have a 2nd set of pre outs its destined for the scrap heap.

IDK.

Clipdat

No, I mean is that why it would go in the scrap heap if it doesn't have a second set of outputs? Because then you wouldn't be able to hook up your subs?

kharp1 wrote: »

IDK.

mhardy6647

It's (apparently) OK to use Y-connectors for preamp outputs to split signals. It's not like mixing two channels to one with a Y-connector "the other way".

txcoastal1

mhardy6647 wrote: »

It's (apparently) OK to use Y-connectors for preamp outputs to split signals. It's not like mixing two channels to one with a Y-connector "the other way".

That's how it would be wired inside the pre with dual outs

Doug made me custom cable to do mine

Clipdat

Got a pic? Trying to visualize what you are describing.

txcoastal1 wrote: »

Doug made me custom cable to do mine

txcoastal1

All male Y-cable from my W4S Dac/pre to my Ampino amp and to my sub

It's my desktop rig with LSi7, no crossover setting all full range near field

kharp1

I would have to believe that a pre with dual outputs would have some resistance added. Been several years since I was in that class, and, we don't do much of that here. Lot of plug and play components (proprietary) and logic changes (which is what we do mostly).

Not saying that a splitter won't work, we all know it does, but, I think proper utilization would require modest circuit changes.

mhardy6647

kharp1 wrote: »

I would have to believe that a pre with dual outputs would have some resistance added. Been several years since I was in that class, and, we don't do much of that here. Lot of plug and play components (proprietary) and logic changes (which is what we do mostly).

Not saying that a splitter won't work, we all know it does, but, I think proper utilization would require modest circuit changes.

Well -- buffers are nice, but, no it's not actually strictly necessary.

http://www.rane.com/note109.html

Introduction
Wye-connectors (or "Y"-connectors, if you prefer) should never have been created.

Anything that can be hooked-up wrong, will be. You-know-who said that, and she was right [I have no idea what this is meant to refer to ] A wye-connector used to split a signal into two lines is being used properly; a wye-connector used to mix two signals into one is being abused and may even damage the equipment involved.

Here is the rule: Outputs are low impedance and must only be connected to high impedance inputs -- never, never tie two outputs directly together -- never. If you do, then each output tries to drive the very low impedance of the other, forcing both outputs into current-limit and possible damage. As a minimum, severe signal loss results.

Monoing Your Low End
One of the most common examples of tying two outputs together is in "monoing" the low end of multiway active crossover systems. This combined signal is then used to drive a sub-woofer system.

Since low frequencies below about 100Hz have such long wavelengths (several feet), it is very difficult to tell where they are coming from (like some of your friends). They are just there -- everywhere. Due to this phenomenon, a single sub-woofer system is a popular cost-effective way to add low frequency energy to small systems.

So the question arises as how best to do the monoing, or summing, of the two signals? It is done very easily by tying the two low frequency outputs of your crossovers together using the resistive networks described below. You do not do it with a wye-cord.

(etc., etc., etc.)