Need help with spring rev driver reciever

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

mich

Well-known member
Joined
Oct 31, 2004
Messages
449
Location
Israel
Hi,
trying to build a tube spring reverb circuitry for studio use.
source will be sent directly from converter ,and output of the reverb is going into the converter input (no need for 600 ohm)
i've attached a first draft - let me know if you see problems with this.
Thanks
 

Attachments

  • tube spring reverb.jpg
    tube spring reverb.jpg
    38.8 KB · Views: 84
You have consistently put the pots the wrong way round (it would more or less work that way, but it's not the "academic way).
What are the characteristics of the tank (input and output Z)?
 
the reverb tank's input Z is 8 Ohm, and output Z is 2250 ohm.

i see what you mean with the pots - the input goes to one side of the pot and the wiper should go to the grid.
that way when the pot is turned all the way CCW the grid is at ground as opposed to now when the signal is at 0 but the
tube is "open".
 
> when the pot is turned all the way CCW...

....the signal source is shorted with a 500pFd cap.

If fed from modern "line" outputs, probably OK. It sure would kill treble of any tube stage it was tapped from.

Are those 100uFd caps for coupling and cathodes? Typically you want to lose bass through a reverb tank. Anything under 500Hz is muddy and fake-sounding. Anyway 100uFd as a plate-grid coupling cap will be large/costly or leaky.

Likewise 10uFd output cap seems ample to me, and 1uFd is a better choice for low output DC leaking without absurd cost.

Larger cathode resistor on the high-current output stage than the low-current gain stage? Seems backward to me but I'm not going to study the lines.
 
Are those 100uFd caps for coupling and cathodes? Typically you want to lose bass through a reverb tank. Anything under 500Hz is muddy and fake-sounding. Anyway 100uFd as a plate-grid coupling cap will be large/costly or leaky.

cathodes yes, but for the coupling its actually 100nF. (im sorry for the somehow blurry schematic -  it didnt convert well from bmp to jpg..)

and the output cap is 3.3uF (film) - for these i have at hand.

so maybe no bypass caps on the cathodes is better soundwise ?i put them there for the extra gain.
also i thought i would need a flat respone from the reciever part - as i can always chop it up further down the line (in the DAW)

about the load lines - again , i was trying to get the most gain out of the least # of tubes . but its certainly possible that
i made a terrible noob mistake..

Thanks again
 
Here is an updated schematic -
it could use an extra 10dB in the reciever gain stage - but perfectly workable as is.actually sounds fantastic....
 

Attachments

  • tube spring reverb.jpg
    tube spring reverb.jpg
    160.7 KB · Views: 39
and some pics to prove that im not joking -
 

Attachments

  • back.JPG
    back.JPG
    494.9 KB · Views: 35
You might want to have a look here http://www.tellun.com/motm/diy/tln156/TLN-156.html

I have built one and it works great. Might spring some ideas to mind.... (docs included in the page).
 
These 10 dB could be had very simply, by increasing the value of RV1 to 470k or 1 Meg.

are you positive about this?

i had 150K in there ,and it wasnt a big difference. also simulating shows almost 2 db gain increase (from 22k to 470k)

the tank spits out ~6mV RMS when driven properly - so is it even possible getting 50 dB from a single  12BH7?
on the second plate of the 12BH7 ive got 10 mA for lowest output Z - around 5K?
the first plate eats 2 mA - and  sits @ 50V - but thats fine because of the very small input signal..true?

whomper ,
nice work there - and thanks for the help - as you can see im trying to wrap my head around load lines & tube stuff before getting to the actual spring sound...
 
mich said:
These 10 dB could be had very simply, by increasing the value of RV1 to 470k or 1 Meg.

are you positive about this?

i had 150K in there ,and it wasnt a big difference. also simulating shows almost 2 db gain increase (from 22k to 470k)

the tank spits out ~6mV RMS when driven properly - so is it even possible getting 50 dB from a single  12BH7?
on the second plate of the 12BH7 ive got 10 mA for lowest output Z - around 5K?
the first plate eats 2 mA - and  sits @ 50V - but thats fine because of the very small input signal..true?

whomper ,
nice work there - and thanks for the help - as you can see im trying to wrap my head around load lines & tube stuff before getting to the actual spring sound...
you would need to replace the BH7 with a standard high-gain tube like a 12AX7. There's no point using a low-mu tube in this position.
In fact putting the BH7 seems to be more adequate for the drive position, not the recovery.
 
you would need to replace the BH7 with a standard high-gain tube like a 12AX7. There's no point using a low-mu tube in this position.


you are absolutly right.  -  what was i thinking?!
I think i wanted to provide lower impedance output to a lower turns ratio output transformer - and than thought i dont really need
a balanced output.
Thanks for your help!
 
Back
Top