PRR Vari-mu

[Michael Krusch]

Yes it is.

 

[PRR]

> isn't the releasetime affected by the attacksettings

My mistake, and I posted a correction, probably in this thread.

 

[SUPERMAGOO]

thanks to everyone for your help.i think that the monitoring in my lab is not of a good quality and the signal input was previously compressed and didnt realise.maybe it works fine and i dont know it.im going to make it again and test in my estudio.
rafafred entiendes español?

 

[Larrchild]

I found a cheap 10k to 10k ct xfmr rated to 30khz,
http://www.edcorusa.com/transformers/audio/wsm/wsm10k-10k.htm

9 dollars and change. Find an old scope carcass and tinsnip yerself a mumetal box. lol

It might not suck to have a higher z and a 10k bridging input.

 

[Svart]

i used the cheapo trannies from a Radio shack filter. it sounds wonderful with those.. you'll be highly suprised.

 

[gyraf]

There's recently been serious problems with the car-filter type line transformers - I've tried five different suppliers and all has recently changed to a new type/manufacturer that clearly does not know how to wind audio transformers. Input resistance for decent low-end is now very-very low, indicating that primary inductance (core material?) is very poor.

None of the suppliers had any solution to this - seems like the old supplier has dried out or something.

It would be very interesting to know who actually manufactured these transformers, as there seems to have been only one OEM manufacturer making the innards for several brands (otherwize it wouldn't make sense that all available suppliers suddently got the non-working type)

Any ideas?

Jakob E.

 

[Larrchild]

Here's a 10k to 600 ohm model. Same price.
http://www.edcorusa.com/transformers/audio/wsm/wsm10k-600.htm

I guess curiosity is going to force me to find out how good an under $10 xfmr sounds.

 

[NewYorkDave]

Do a search. Edcor xfmrs have been discussed here extensively. I've run some tests on the WSM series and the short story is that they're very good for the money.

 

[Larrchild]

excellent. It seemed too good to be tru. BYOM bring yer own mumetal=)
Thanks.

 

[NewYorkDave]

You don't want a VU meter buffer, since what you're trying to read is direct current. Instead, try a DC microammeter in series with the cathodes as in the Altec 436C. Make the shunt adjustable for calibration purposes.

 

[NewYorkDave]

I said microammeter, not milliammeter. The tube is never going to draw enough current to make either of these meters do more than barely twitch.

 

[Larrchild]

I've had good luck with a vu meter(non buffered), internal rectifiers included.. I use a cal pot and also some small negative bias off another pot on the ground side to calibrate it in db's of gr.

This allows a 5 pos 2 pole switch that looks at in/out/cathode a/ cathode b/ and gr on the VU meter.

on in and out a buffer amp is indicated.

 

[dukasound]

Hi
Can I use in PRR Vari-mu Beyer line transformers:
Here are some specifications:
1:1 (1K/1K)
30-15000Hz +/-0,5db
Max input for 1% THD, 8V on 30Hz
Thanks
Duka

 

[mikeyB]

Did the 10k:10k transformers work? I got some sowter 3575's which would keep cost down!

 

[Larrchild]

Larr-- sounds interesting, would like to try that out as well. I just want to get the metering happening so I can get the face on and get this baby racked

As Gyraf has pointed out, a VU meter is not the best choice for a GR meter. His meters are linear in their display of, say. -10, -20, -30 dbgr, whereas a VU can be linearized for the 1st 10db or so of GR, then it gets ugly.

But the 1st 10db is what most folk are interested in. If you need to see -30dbgr, get a microamp meter!

 

[rafafredd]

If you need to see -30dbgr

mmm.. sometimes I go way down on my (heavily moded) STA LEVEL for some tracks. Sounds interesting.. It meters -40dB and lower alright.

 

[Larrchild]

Yes, I gave Tom Lord-Alge my SR-71 limiter protoype, when it only did -25 dbgr, and he said "Not enough", so I made it -35 dbgr. I know what he meant, after hearing it.

It's intense! :shock: So, yes, you folks exist. Now I know.

 

[PRR]

Gibson GA100

6BD6

 

[Gus]

I never saw that schematic before. Very cool, a voltage reg, interesting tone control and also the reason its posted. Neat how it uses the PI for the control amp section and a PI for the rest of the circuit.

What year? it has a 3 wire plug. It might be a very cool sounding bass amp.

 

[dukasound]

Hi
I start to build PRR Vari-mu and I have a couple questions.
Because I will use only one meter and attack and release control how to wire board.
Does R39 -1k pot is dual for both channel or one per channel.
Too, how to adjust R32 -100ohm trimer. I haven’t any osc.
I will use one 1mA meter and how to draw scale.
On the end my other equipment is +4dBu. Can I use some circuit (IC buffer etc) to increase signal.
Thanks
Duka