Paramour II - 76 driver

[elcraigo]

Yes once again, 76 in the Paramour. Finally building the Paramour II, and putting the 76 in from the start.
Have sockets, have tubes.
2A3 configuration w/ the original BH upgrade Output trans. for Para I.
I have dug (some deep drilling) though old forum for info. Just need a check.
(C4s) same as the stock, don't use cathode LED, and use a 2.21 K (have in the stash).
I've come up with 8.5 V bias and 3.9 mA thru the 76.
This good? Thoughts for experiment?

thanks - Craig

[Paul Joppa]

Looks good to me. You should see about 175v at the plate.

Experiment 1: bypass the cathode resistor (2.21K) with a capacitor - probably anything over 22uF will be adequate. It will improve the "drive" (reduce the source impedance) but will add capacitor sound. Purists don't like cathode bypasses if they have a choice, but there is a tradeoff so the experiment will be educational no matter how it turns out.

Experiment 2: raise the current as high as 9mA (change the 237 ohm R1 to 95 ohms - or parallel it with 160 ohms) and drop the bias to 6 volts (cathode resistor 667 ohms or something close - 680 is common). Plate voltage will still be about 175 volts. This runs the 76 "low and hot" giving - again - more drive, and the smaller resistance (when unbypassed) translates to lower source impedance compared to the 3.9mA condition. The Paramour II can provide the extra current, which the original Paramour power transformer cannot.

[Grainger49]

Craig,

I did a how to after my Paramour (1) conversion then Doc sent me a Paramour II manual and I published that.

I'll email.

[Jim R.]

So, can I ask what this does for the sonics?  It looks like the mu is pretty low too, so I'm asuming one would need a preamp with this setup?  I'm planning on a FP III+ or one of the other designs in the wings in the not too distant future anyway.

Is the 76 a DHT?  The data sheet didn't mention anything and of course none of the data sheets show the pinouts in text form.

Grainger, can you email me those directions?

If I don't go with this, it will be the 6j5.

Thanks,

Jim

[Paul Joppa]

The 76 is indirectly heated. It is a 56 with a 6.3v heater. (The 56 runs 1 amp at 2.5v, which would let you use it if you are using 45s in the output ...) Both have 5-pin bases, the octal version is a 6P5. The versions I've seen have cylindrical plates, which often indicates some care in making the internal geometry symmetrical and hence more likely to be linear; however I haven't done any measurements to test this theory!

The older prototype 27 is similar but an even lower mu (9) and higher heater power requirement (1.75A at 2.5v).

The next newer one is the 6C5, with a mu of 20 and a plate resistance (rp) of 10K. Then came the 6J5, mu 20 and rp 7700. There is also the 6L5, mu 17 rp 9K - this one is probably later because it has a lower heater power. (It may have led to the 7-pin mini 6C4 and 9-pin mini 12AU7.) All the octal 6.3v heater tubes mentioned here have the same socket wiring and are similar enough in specs that you could probably swap them with no other changes.

[Grainger49]

Jim,

Sonically I liked the results.  The sound was smoother and less sterile, not that the 12AT7 is sterile, I just can't think of another word for it.  Visually, not a deal breaker for you, it is nice having two bottles the same shape on the amp.  The 12AT7 is just so tiny next to the 2A3.  Kind of a very cool retro look.  Others will be impressed.

When I changed the driver, I had already had Chacodude's 76 driver Paramours in my system during a listening session, I had a drop in gain.  My FP 2 made up the difference.  My room is 23' X 13' and I listen in the mid 80dB range.  I have to run the FP 2 almost all the way up, say 3:00 with my Seduction but back nearer 12:00 for CDs. 

Two last things as I read your post, do you have Paramour 1 or 2 and do I have your email.  I would check but I'm on the laptop and it doesn't have my email.

[Jim R.]

Thanks, PJ -- good stuff to know!

Grainger, amps are paramour IIs and I do believe you have my email, but let me know if you don't.

Thanks,

Jim

[elcraigo]

thanks .. PJ for the experiments and Grainger for the docs!
I've plugged it all into the spice model I have.

[elcraigo]

New Legacy - Better later then never

[Jim R.]

So, how does it sound?

-- Jim

[elcraigo]

Everything is still new. The 76 are new. The 2A3 are new Shuguang. All not broken in.
The only older part is the output transformer (it's a original BH upgrade for Para I)
Unless you count the parts sitting in the box for years old ;-)

Sound - I'll put it this way: I was listening to Para I's w/ 45 mesh, EXO45 Nickel Pinstripes, BCP15, para II pwr trans. and SR45.
I really like the way this sounds so far with the 76, and have no desire to put the Para I / SR45 back in.
While listening to vinyl, I took one record off because the recording was pretty bad; I never really notice this before.
One record (which did sound nice) was unopened; I bought it a 2-3 years ago, and had forgot about it. See, this new old legacy is starting to be a theme.
Vinyl setup is: VPI scout, Ortofon HMC30, Cinemag step ups, Seduction.
Yes - the gain is lower. I have an ext. Foreplay III and 100 dbSPL speakers (DX3 in large MLTL); it's not a problem for me.
The only snag I ran into: My wife really liked the red color (brilliant crimson dye) until I told her where I was putting the amps. Her comment, they really jump out at you.

Again - thanks to PJ for the experiments, I plan to do both after I listen a while; and to Grainger for the documents.

.. Craig

[Jim R.]

CrCraig,

Ok, sounds interesting and promising.  I'll be using my Paramour IIs also with Lowthers, but a dx-55, and in a somewhat unconventional box -- the fostex bk-16s (with some tweaks).


Thanks for the update,

Jim

I tried to order some ux5 sockets the other day but the place I want to get them was all sold out of the ones I want.

[elcraigo]

I have (2) unused ceramic UX5 sockets (same as in the photos).
I really doubt I will ever use them, or at the rate I build kits, let alone scratch built stuff; it will be long awhile.
You are welcome to them - just shoot me an email

Craig

[Grainger49]

Craig,

You are welcome.  I'm just glad someone is using the information.  Your JPG below the post will answer a lot of questions that will surely come up.

Enjoy!

[Jim R.]

So, how does one tell which pin is 1, and how do you assure correct alignment of the tube in the socket?  I just recently sold a box full of antique tubes so I don't have any more 5 or 6 pin tubes around to check.

Thanks,

Jim