Z Wreck

[ampmike]

Thanx for those pics,Not a whole lot inside a Zwreck!!Very nice lookin!,Mikey

[wsaraceni]

i love the clips of this amp.

[M Fowler]

Maybe it is the choke I used, Hammond 158L 15hy, but my wreck build stays very clean to about 3 pm on the volume knob. I might try a different choke to see how that interacts.

Have it switched from 260 to 300v HT Heyboer 5199 and 4k3 Heyboer
which is not M6 steel so all the differences in components I used are probably adding up. Did not use all MF resistors either.

I ordered the correct Russian EL84's and will see how those work out. Running GT 12AX7 gold series right now for preamp and PI.

Mark

[Bruciep07]

Maybe it is the choke I used, Hammond 158L 15hy, but my wreck build stays very clean to about 3 pm on the volume knob. I might try a different choke to see how that interacts.

Have it switched from 260 to 300v HT Heyboer 5199 and 4k3 Heyboer
which is not M6 steel so all the differences in components I used are probably adding up. Did not use all MF resistors either.

I ordered the correct Russian EL84's and will see how those work out. Running GT 12AX7 gold series right now for preamp and PI.

Mark

Where did you order tubes from Mark? One thing I'm having a real tough time with is buying NOS tubes. For me, tube dealers fall in to 3 categories... Seller #1 offers tested matched tubes (though not always telling you how they were tested/matched) for one weeks paycheck, seller #2 has "tested NOS tubes" (which is a fancy way of saying used but still good), decent pricing but no guarantees, and seller #3 is so eccentric that I can't convince myself to just them money without knowing anything about what I am getting, other than them being "the rarest Russian types"...

[M Fowler]

Bruce,

http://tubes-store.com/

For the Russian type tubes. 6P14P-EV / 7189A / 6BQ5 / EL84M tube

[Richie]

current made tubes preamp tubes, try the Svetlana. When they first came out years ago, they were probably the worst made. They recently went back and redesigned it,and Now they are one of the better currect made tubes. I bought 10 to give them a try, no testing,just what 10 came in the lot.
And 8 out of 10 worked in V1 of the Express. I know some may say you need to use NOS tubes, and yes they do sound better. But if you can't afford the NOS, then try the svets.
Some say the reissue Mullard are good too. And some places test these for gain and microphonics..just a few dollars more. May be worth the hassle. I got mine from new Sensor. But many other places offer them tested.
I also seen some places wanting NOS prices for tested current made tubes..


As for the russian tubes.. here is a link that has the cross for most tubes.
Also you can look into what some ratings mean. Like the EV,K,ER,EB, etc.. some meaning 5000hr tubes. some 10000 hr rated tubes. Or heavy military shock tested tubes. Which may be less microphonic.

Also the tubes that they use for preamp tubes. Do some research,they have those in 10000 hr rated tubes. If its your own amp, its a very small difference in wiring the heaters to use those tubes. You could probably install a switch, to run standard 12ax7 or the russian type.
Find out what plats made them,and all that.
http://www.klausmobile.narod.ru/td/list_e.htm#Dual triodes 2

[Bruciep07]

Bruce,

http://tubes-store.com/

For the Russian type tubes. 6P14P-EV / 7189A / 6BQ5 / EL84M tube

Thanks Mark,

I actually have 10 or so Reflector 6P14P-EV's that I picked up for just a couple bucks a year or so ago. Un-matched in white boxes, but I sent them to Selloutrr to test for me, I haven't touched them since I got them back though. I was gonna just use them as start-up tubes, maybe I'll rethink that...

current made tubes preamp tubes, try the Svetlana. When they first came out years ago, they were probably the worst made. They recently went back and redesigned it,and Now they are one of the better currect made tubes. I bought 10 to give them a try, no testing,just what 10 came in the lot.
And 8 out of 10 worked in V1 of the Express. I know some may say you need to use NOS tubes, and yes they do sound better. But if you can't afford the NOS, then try the svets.
Some say the reissue Mullard are good too. And some places test these for gain and microphonics..just a few dollars more. May be worth the hassle. I got mine from new Sensor. But many other places offer them tested.
I also seen some places wanting NOS prices for tested current made tubes..


As for the russian tubes.. here is a link that has the cross for most tubes.
Also you can look into what some ratings mean. Like the EV,K,ER,EB, etc.. some meaning 5000hr tubes. some 10000 hr rated tubes. Or heavy military shock tested tubes. Which may be less microphonic.

Also the tubes that they use for preamp tubes. Do some research,they have those in 10000 hr rated tubes. If its your own amp, its a very small difference in wiring the heaters to use those tubes. You could probably install a switch, to run standard 12ax7 or the russian type.
Find out what plats made them,and all that.
http://www.klausmobile.narod.ru/td/list_e.htm#Dual triodes 2

Thanks Richie,

My Russian isn't very good, however a picture is worth a thousand words

I have some Russian 6N something or others (12AX7'ish with parallel heaters, think 6N2P's?) that I picked up with the 6P14P's for next to nothing, I was kind of saving all these tubes to do a 2xEL84 Rocket some day. Ebay isn't always the best option for buying tubes, but part of me wants to pick up a case of the Russian 12AX7's and just put them in my closet and forget about them for a while. They are really really cheap for what they are, I've never heard one in person though and have read mixed reviews, but still, 100 of them for under $2 each shipped, bound to be some decent sounding tubes in there...

[Richie]

Look up some Red Bear Amps info. they used them in there, and show the conversion. Like any of those tubes, some are made at different factories, and old production. Some cost quite a bit depending on what ones they are.
but yeah, worth a try. They are supposed to be super low microphonics.
Some tube dealers have them too.

[Bruciep07]

Sound pretty good for $2 tubes I may just pick up some more before they get too hyped up, after all, these will be $50 tubes in 10 years... Seems the "Voshod Plant" tubes are the ones to look for, or at least that's what my 10min worth of research has told me. They have a sideways missile screened on the glass, looks like I'll be spending my afternoon looking these up...

[TheGimp]

I have about 100 of the 6N2P-EV which is supposed to be equivalent to the 12AX7, except that they are wired as 6.3V from pin 4 to 5 with pin 9 as a shield between triodes.

The date codes I've used so far range from 1976 to 1989. Out of the 20 I've used so far I have only found one that was a problem tube with a lot of hum when used in an input stage, but no problem when in the PI position.

This particular tube had the highest noise when used in the first three gain stages out of the 20 tubes as well (of a Liverpool derived amp), but did not have the highest gain (no coorilation between noise nad gain).

[M Fowler]

The 6N2P-EV will be my next purchase I need three.

[argonaut]

Thanks for posting the pics and sound clips. IMO, anyway you slice it, it's an excellent sounding amp. Nice job, Z.

Can anyone make out (or know) the value of the bypass caps on the cathodes? I see they used one on V2.

[TheGimp]

Not meaning to hijack the thread, but I remembered something else.

I noticed the 6N2P seems to produce more noise than 12AX7s, based on the problems I had with hiss in my Russian wreck compared to what I've read others post.

I went back through my notes and I did throw out one tube that was the worse. I saw a spread of 17mV to 87mV excluding the one that I threw out which measured 128mV.

I measured the noise by setting up the amp with no input, all controls to noon except volume to max. Then I tried each tube in the first gain stage position and recorded the noise measured with an oscilloscope doing RMS reading with the sweep on 250uS/div and gain at 20mV/div. Once I measured the noise I tried different tubes in the three positions to see how it effected noise. As expected the PI was pretty much insensitive to which tube was in that position. Second tube was next and the first stage most sensitive. The tube that caused a great deal of hum in V1, produced no discernible hum in the PI. I placet two of the mid range tubes in the PI and second tube position and re-measured all tubes. The ranking remained the same.

Unfortunately I only have a handful of 12AX7s and most are used so I have not done a direct comparison to see if the 6N2P is truly noisier.

We might want to start a new thread if there is more discussion.

[Bruciep07]

Unfortunately I only have a handful of 12AX7s and most are used so I have not done a direct comparison to see if the 6N2P is truly noisier.

We might want to start a new thread if there is more discussion.

That's a great idea since we keep hijacking this thread, now everyone go out and buy some 6N2P's and put them in your wreck We'll compare notes later...

[M Fowler]

Bypass caps read 25uf/25v to my eyes and that is the value I used to build my Zwreck.