[harryf]

C7 and c15 are listed as 470 nf cap's.I have found this is the same as a .47uf cap.
Can this cap somehow be changed to a .33 cap?the reason is is that i have a few auricaps and russian k40's in that value on hand.They are of better quality than the one's i have on order.
Second i am going to make a custom cabinet for this amp instead of what's normaly used a metal cabinet.I am useing a solid maple cab with a steel top.I was going to route out a square peice on the end of the amp then mount a metal plate with the rca's and powercord switch in it.
Will this work?I'm worried about the ground.Is there anything special i need to do to get away makeing this set up hum free?
Third those 6h30 tube's! Wow they are super expensive!
What brand is best and what are the differences between them?
What's a fair price?I found a place from russia selling them for 18 a tube.Most us seller's are way above this.Where to buy?

[harryf]

Jim you out there?Would a 6n6p tube work?I read a post that said it might.I can get 10 new for what one 6h30 costs?

[flocchini]

I am using the 6H6P in my Castanet and love the sound. I also have substituted the 6H6P for 7304s in a low voltage preamp with battery powered filament.I know this doesn't answer your question directly but this has rekindled my interest in maybe building a pair of Cymbals.
I found this article interesting
http://www.lampizator.eu/UPGRADE/upgrade%20noval%20tubes%20to%206H6P.html

[Yoda]

One option might be a group buy? 

I have a pair of cymbals (as of Saturday  ) and a castanet, so thats a lot of 6h30s.  I do think that all of those 6h30's at $18 each, with their 10000 hr plus life is fairly cost effective option over time compared to other expensive tube types.

Although there are a couple years left on my current tubes, I am interested in your 6h6p swap in the castanet, flocchini...did you do anything to the circuit?

[harryf]

I read that article but i don't read russian but i wonder if 6hp6 might not work.It seems that it might work.I'm still trying to figure out if it's a direct swap.It seem's they have the same pinout so maybe...

[Bill Epstein]

I was going to route out a square peice on the end of the amp then mount a metal plate with the rca's and powercord switch in it.
Will this work?I'm worried about the ground.

Better to counterbore and drill holes in the wood itself which eliminates the issue of the RCA neutral barrels grounding to a metal plate.




Create a star ground as usual including a safety ground to the transformer/top plate.

[flocchini]

One option might be a group buy? 

I have a pair of cymbals (as of Saturday  ) and a castanet, so thats a lot of 6h30s.  I do think that all of those 6h30's at $18 each, with their 10000 hr plus life is fairly cost effective option over time compared to other expensive tube types.

Although there are a couple years left on my current tubes, I am interested in your 6h6p swap in the castanet, flocchini...did you do anything to the circuit?

I just dropped the 6H6P into the Castanet. I was really pleasantly surprised. The author of the article I referenced above uses a lot of Russian tubes in his DAC mods. I purchased the tubes on eBay for about $3 each. It takes about 3 weeks for delivery

I have also used the Russian military 6H8C/1578 as a replacement for the 6SN7 in my Cornet2 and Chime. These are nice. Unfortunately they have been discovered and are increasing in price.

Best

Bob
[/quote]

[harryf]

I bought 10 russian 6h6p's for 30 buck's shipped.I'm a novice but i looked at the voltages and the data sheet for the russian tube and it look's like it might work.
If it does not i'm out less than what one 6h30 goes for.
The wood cab?You think i chould just drill a hole and mount the rca's in the wood?
Is this what your suggesting bill epstein.That would certainly be easier.
I'm actually thinking about maybe putting the whole thing inside a cabinet and mounting a grill on top of it.Sort of what trainwrek guitar amp's look like.
It might be a much larger case but in solid wood it would fit right in with my vintage amp's and receiver's i already have.

[poty]

... i don't read russian

If you need something - I could translate it for you.

[Yoda]

harryf let us know how those tubes work for you in the Cymbal.

[harryf]

I have studied the two tubes datasheet's and i find that most of the spec's are similar,very close.I have read the voltage's on the cymbal's schematic and i find they will be in spec.I think?I'm no expert.
Where i see a difference is in the internal capatance's of the tube.It seems the 6h30 is slightly higher in spec.Does this matter?I wonder why the russians would make two tube's so similar.I do notice the 6h30 will go 50 c higher in temperature and can take 30v more peak power.The really are very very similar in spec's even the graph's.Like i said though i'm no expert.
I wonder is there a program you can model a amp like the cymbal with a different tube?Something that will tell you if a resistor or cap value need to be changed?
I also wonder if i do get it to run what do i bias it at?) like a 6h30?

[harryf]

Ok each cymbal calls for 2 .47 uf cap's 400 Part's connection messed up my order<Again!>What i have on hand are .33 600v auricap's and .1 uf multicaps 400v.I have parrelled them and i get .44.I have read that this will be within tolerance's in most circut's so i could use these in place of a .47 cap.
If this ok what do you think?old stuff was + or - 20%.I'm not sure about this new circut though?
I'm not worried about parrelleling them as they are actualy better sounding part's than what i originaly ordered.Any opinion?
I don't really want to order the same auricaps but .03 higher if i don't have too.

[poty]

... each cymbal calls for 2 .47 uf cap's...
... i get .44. I have read that this will be within tolerance's in most circut's so i could use these in place of a .47 cap.

I think you are right. There is no problems with changing slightly the capacitance in this part of circuit. Maybe slightly more than .47 is better than slightly less, but it could be easily changed in the future.

Where i see a difference is in the internal capatance's of the tube.It seems the 6h30 is slightly higher in spec.Does this matter?I

I don't think so. The schematic of the amp is rather rigid, so you can easily do tube rolling.

I wonder is there a program you can model a amp like the cymbal with a different tube? Something that will tell you if a resistor or cap value need to be changed?

I don't think there is a program, but if you have specs you can find the right values by himself. In reality usually the values get by trying in the circuits different resistors and capacitors to get the best result (around the common values of course). I don' know where to find the theory in English to give you a reference.

I also wonder if i do get it to run what do i bias it at?) like a 6h30?

I don't think you will have to change anything. I think it will be good "as is".

[harryf]

Ok great reply.I just built the chime and now i'm doing the cymbal.It seems their are way fewer guy's who built these kits so any help i apreciate!
I have a bunch of solen's 1 uf caps i can run those in series to get .50 uf.They fit better in the chassis too.They wont sound as good though.Oh well.

[Yoda]

I think you could try it both ways.

[harryf]

I just happend to find some good .47's in my part's box.So i'm building my wood case and waiting on tube's!