New Build - Z Wreck Style

[vibratoking]

So the 135 failed was from 300 I purchased in 3 months.

45% failure rate for Tung Sol 12AX7s and 60% for JJ EL84s?

I wonder where the rejects are ending up? I am guessing that they are not being thrown away, but are probably being 'distributed' to someone else. That someone else is likely us guys that buy them in small quantities.

I don't like what I am hearing...rattle, rattle, rattle

[Reeltarded]

I have some JJs I bought recently. I was very happy until I lost one, then not as happy, but still..

Then I opened up the other quad yesterday and retired them to emergency spares. They bias exactly like another main quad I have, but they rattle like a snake.

[Colossal]

That was one quarters worth.
I order 100 of the tung-sol 12AX7's a month.
So the 135 failed was from 300 I purchased in 3 months.

DR.Z

Wow Doc, that is an alarming percentage...thanks for the heads-up.

[rhinson]

That was one quarters worth.
I order 100 of the tung-sol 12AX7's a month.
So the 135 failed was from 300 I purchased in 3 months.

DR.Z

hopefully mr. matthews won't decide those you sent back are ok and sell them to me next time i order 10-20pcs. rh

[richiemays]

I build about 15 amps a month, and I return or throw away about 25 to 30 percent of the preamp tubes that I buy. This includes JJ, EH, Tung Sol, TAD "premium", and Mullard reissues. Dr. Z is absolutely right about the horrible inconsistency of the major tube manufacturers. I just got in 300 JJ ECC83's yesterday, and I'll probably have 50 of them be unusable garbage. Its just kinda the way it is, and there's nothing any of us can do.

In response to the retail cost of boutique amplifiers, none of the boutique builders are making mega millions. In this business, you have a ton of expenses that most DIY dudes don't have to deal with. Shipping, advertising, employees, insurance, taxes...it all adds up. You've all heard it before, but "The best way to make a million dollars in the amp business is to start with two million dollars".

[Tillydog]

.... Its just kinda the way it is, and there's nothing any of us can do.

.....

I think you (and others) are doing the best thing by returning the poor quality tubes.

My concern is that the returns just get re-routed to less discerning or less important customers, i.e. us! (I've worked in manufacturing - It Happens.)

I would be curious to know what criteria that you volume buyers use to screen the tubes - do you look for characteristics on a tester? Sound test them? How else?

Do you think a low volume buyer could get away with returning tubes on the same basis?

Andy

[surfsup]

My concern is that the returns just get re-routed to less discerning or less important customers, i.e. us! (I've worked in manufacturing - It Happens.)

Was thinking the same thing, and I *do* work in manufacturing and yea, that's what happens. The cost of a new box and a wipe-cloth to remove fingerprints is less than adding scrap cost. I will have to check the tube pins carefully to see if they are worn.

[steve_p]

Hi All,
I figured i would post an update:

I had been playing the amp for awhile and was fairly happy with it. I had this feeling that it was breaking up earlier than it should, and not in a completely pleasant and musical way.

So, I had to replace the socket on my PI tube that got slightly screwed up when i built it...i was able to get a tube in and out, but it was very tight. I think a small dab of solder worked its way down to the socket.
As i was desoldering, I noticed that pin 7 on the PI was never soldered.....whoops. It was tucked into the terminal, but was probably making intermittent contact at best.....

So, I replaced the socket, checked all my connections and WOW!!!
This thing is truly amazing now. Breaks up very nicely and cleans up quite well with the volume knob. This was with my squier CV50's tele.... I might give it a go soon with my lester as well.

Anyways, I am getting ready to build my cabinet. Here is a very exciting picture of what will turn into the head:

[IMG612]http://i674.photobucket.com/albums/vv10 ... AG0386.jpg[/img]

18mm Baltic Birch for the shell and a piece of hard maple for the front valence.

I will post some more pictures as I progress.

Steve

[wsaraceni]

While I have no reason to doubt Dr. Z, I find it hard to believe his material costs would be the same as one of us hobbyists.
But his labor costs are surely a big part of the price of his amps.

We have to pay retail for parts and I would assume that Dr. Z is able to get wholesale due to buying in quantity.

When I build an amp, I can't get everything from one supplier so I have multiple shipping costs that quickly add up.
On a complex build these costs can quickly reach $100.
Add in the mistakes made when ordering wrong parts and there is another chunk of change.

I don't count my labor costs but if I had to I would probably have to pay myself about $1.00/ hour if even that much.

I have an idea about how hard it would be to make a living doing this and the amount of years required to get established.

So my hat is off to men like Dr. Z that can make a go of it.

if i had to count labor costs for my express, i could have bought one for $30k and it would now work. (mine doesnt)

[M Fowler]

I would love to buy some amps especially from good ole Doc Z love his work.

I also would rather buy a Dumble style amp from Jelle or others then make my own. I can't stand working them or trying to source all the components these parts hogs require.

However, buying parts over a period of time for a home built amp is so much easier for me then dropping $2-3k at a time. I should learn how to save for what I want, huh?

My plan this summer is sell, sell, and sell. I have stuff laying around my garage and shop that need to go (non amp stuff).

Mark

[wsaraceni]

any amps similar to a 2xel84 z-wreck? i've played a few rocket clones and like the z-wreck more if that makes any sense. but i wouldn't mind an 18 watt version to build instead of my 18 watt lite iib. i'll probably have to buy new transformers, but i'd like to give it a go.

[M Fowler]

wsaraceni,

What's wrong with your Express, do you need some community help with it?

An 18w version of the Zwreck can be done I would start with proper transformers though for 18w power rating and keep voltage to about 560VCT. Or the Marshall 18w is 580VCT. OT should be around 8k. In fact using an 18w Marshall set would work very well. I used to use Heyboer set that Turretboards.com sold but he discontinued those so a call to Heyboer could get you a set. Magnet Components also has a set either laydown or standup version PT is available.

The Rocket I built for my oldest son sounds great and he plays through that amp most of the time. I got my transformer set from Dartanion.

Mark

[M Fowler]

wsaraceni,

Forgot that you were talking about changing the Lite IIB into the 18w wreck.

Those transformers are perfect for the build. Doc lowered the filtering in the Zwreck and added the 220k voltage divider otherwise, no change from the Rocket layout TAG has posted in the files section.

While I stopped promoting cloning Zwrecks we are talking about the 18w version so that should be okay if I promote that amp instead.

Mark

[wsaraceni]

right now i have the 18 watt lite iib in the blues jr chassis. i started to disassemble it to add the 18 watt GDS/heyboer OT and add VVR. I think i'll order a new PT and see if that will work better. I think an actual tube rectified PT with the correct voltages would work better. how much is there to change in the schematic to go 2xel84 instead of 4xel84?

[wsaraceni]

also, what choke would be recommended?