Pre-Amp with Phono needs new tubes

[kach22i]

I need your collective help picking out some tubes/valves.

The unit is an Italian made GRAAF WFB ONE line and phono preamplifier, it's a fine sounding piece of equipment if I do say so.

I've owned it for about 10 years and never changed out the tubes. The unit just decided to go silent one day so I'm starting with replacing the tubes (checked the in-cord power fuse already).

Money is tight, and I don't know if I'll just be needing tubes or actual service. However, I only want to do this once, and gravitate towards "bang for the buck" selections over "the cheapest" or "the best". I like "value" and because nobody but me is going to know what's in there, status tubes are of little value.

Here is a scan of the hand drawn diagram which came with the unit, the yellow highlighted tubes must be what was in there before I bought it. I penciled in what is actually there today. The upper left corner four tubes in the phono section have lead wires soldered to a copper mid-ban, with a rubber ring over them. I've never seen anything like it before, and venture to say it's going to be fun replicating the installation skill of the technician before me (I think I can do it).

http://s184.photobucket.com/albums/x295/kach22i/Stereo/

A page form the booklet which came with the unit.
http://s184.photobucket.com/albums/x295/kach22i/Stereo/

I seem to lack some basic education regarding tubes, why is a PC900 also called a 4Ha5 for instance?

And how can JJ E88cc tubes replace both Sovtek 6922's and NOS Reflector 6h23N-EB's?

I have dealt with "thetubestore.com" before, but think these might need extra lov'n, maybe "audiotubes.com"?

 

[JackD201]

7308, e88cc, ecc88, e188cc, ecc808 and 6h23n(cyrillic) are all from the 6dj8/6922 family and are all interchangeable

I have zero knowledge about PC900s or 4Ha5s sorry I couldn't be of more help George.

 

[kach22i]

That's cool, I'll just give audiotubes.com a call when I get a chance.

 

[kach22i]

Picture of inside my unit (see below), looks like I'll just change out the four large tubes for now, and see if that gets the unit going.

I received a proposal from the one tube supplier I've seen recommended in the forum more than once (audiotubes.com). The four tubes I need to get started would cost in the $350-$450 range, that is about 4X's what I expected. I'm sure these are excellent suggestions for me, but business has been terrible for the past five years (living off savings at times) and business only recently picked back up, so I have to be frugal.

A few years ago the eight EL-34's and single input tube on my power amp set me back about $275 if I recall correctly. I was thinking the pre-amp tubes (all eight) would be about $100-$200, boy was I wrong.

If I go with the same brand as the tiny PC900's (which I've decided not to change for now), it's still $50 a tube for the Tungsram or $200. I've read some encouraging things about these Hungarian tubes, not quite sure if it only applies to NOS though.

I've requested (out of respect) from the recommended tube supplier (audiotubes.com) a lower cost option. If I don't like the suggestion for some reason I'll go and order with the company I've dealt with before (thetubestore.com) and pick up the Tungsram's.

About the PC900's of which I'm not planning to change out for now. No where on the Internet have I've seen a similar copper ring/band which a lead (shield?) wire can be soldered to. I might have to send an e-mail (to GRAAF) to Italy to figure out what they are doing here, it's very odd.

http://s184.photobucket.com/albums/x295/kach22i/Stereo/

 

[kach22i]

I went ahead and ordered the 6922/E88cc Tungsram's from the tubestore.com.

I also included in the order four $5.00 each mystery tubes as emergency back ups for the 4Ha5/PC900's.

That's done, now on to the next thing in my life.:b