Paraglow - help! Its not a Paramour - sorry; Newbie -

andrewuk · 13757

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Offline andrewuk

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on: December 30, 2012, 11:36:56 AM
Hi I'm new here but having read the 'Valve' CDs I have built a few SEX amps variations. I recently bought a mess that was a Paramour being converted into a Paramour 2 but it is only a third done and, as I like reading this sort of stuff at lunch times, the Paramour Manual 1 and the sheets that show the upgrades travelled with me. I've lost them all including some HT regulators so I'm stuck. I can work out the PSU - that's simple but what HT am I looking for. I can work out the back end but what is the 2A3 cathode resistor? I can't remember the original SRPP 12AT7 but that is only academic as I want to make this a paramour 2 with the CCS board and 6N1Ps (as were supplied!). I need the schematics without them I'm lost and would have to drown my sorrows and use the EX03 -03s and cobalt EXO 036s in a no expense spared SEX amp or ... the Magnequest Horus. Nope I don't want that. What can I do? Are the schematics available, please?  

best wishes to you all - Andrew
« Last Edit: January 03, 2013, 11:13:01 PM by andrewuk »



Offline Paul Joppa

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Reply #1 on: December 30, 2012, 12:26:35 PM
You can purchase the Paramour II manual, which has the circuit diagram as well as the layout pictures etc. Call or email Eileen; you may have to wait until after the New Year - given how hard the gang worked up to Christmas, I would not expect them in the office very early this Monday!

However, it sounds like you have quite an oddball collection of parts. So, if you want more help than the manual, let us know what chassis plate you have, what power transformer, parafeed choke, and output transformer. And which version of the C4S board - the latest one is v.4.4 and marked on the board; otherwise a picture might help. Do you also have the C7-X 10 henry choke (the original plate choke)?

I add incidentally that the EXO-036 is a 2500 ohm transformer, while all the Paramour versions use a 4000 ohm load. And the 6N1P was never supplied for Paramour; it will require some bias changes from the stock circuit.

Paul Joppa


Offline andrewuk

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Reply #2 on: December 30, 2012, 11:47:53 PM
Thanks for your reply Paul - it's worse than that! This is a 'custom chassis' a lot of time and money may have gone into it but it is nothing like a pair of paramour monos. So. I will take pictures and give more info. I'm not bothered with 6N1Ps. I have enough alternatives! But using a 76 with a CCS (as someone on the Board has done) on it is a much more attractive proposition - the thing is, I ought to get a proper pramour up & running first.

Re:- EXO36s @ 2.5K this shouldn't be a problem with a 2A3 surely (with nominally 8ohm speakers), or are the rules different ... yep they are; its not the plate choke is it. Whne I have parafed outputs before I have just found a couple of 'junk' el84 PP type transformers and happily switched on the power. Perhaps its time I learned something.

Andrew



Offline andrewuk

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Reply #3 on: December 31, 2012, 03:22:52 AM
Here attached is a pic of the CCS. I only have the EX036 outputs and the EX003 plate chokes. The two mains transformers give 360-0-360, 0-6.3 & 0-4volts. I can make out the cap, choke (10Henry), cap nature of the power supply and this worries me as that looks like a lot more voltage than 2A3s will be happy with. That's why I need to know what the HT is on the circuit. My friend had intended to use regulated boards for the H.T. aswell which might soak up some of the voltage but I have lost the notes about these too. Pic attached. (I'll try Google)

happy new year!



Offline andrewuk

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Reply #4 on: December 31, 2012, 03:41:33 AM
P.S. to the above ... The regulated boards are Paul Hynes' of Scotland and very useful they look too. That is quite an exciting icing to the cake.

Ah... sorry... its a Paraglow 2 that I am aiming for, not a Paramour. I'll have a read but please, all I said above is still needed but now I know what I am looking for.

happy new year (again) Andrew



Offline Paul Birkeland

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Reply #5 on: December 31, 2012, 06:41:27 AM

Ah... sorry... its a Paraglow 2 that I am aiming for, not a Paramour. I'll have a read but please, all I said above is still needed but now I know what I am looking for.


I'd send more pictures...  Your description of the power transformers brings up some additional questions that will only be answered with more photos of the parts.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline andrewuk

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Reply #6 on: December 31, 2012, 07:18:19 AM
Hello Paul, the mains transformers are a pair of potted toroidals - not very interesting. The few resistors and solen polyprops throughout look like Solens. Mundorff PSU caps for the 2 X 100mfd at 500v, hexfred diodes, and the magnaquest iron, which I have found out are correct for Paraglow. Looking back on a couple of articles on the board and from 'Valve' I recognise that I need two 4K 50watt resistors for the 2A3 cathode, the parafeed cap(3.3mfd M-Cap - should be bigger?) need not go to ground but to the 2A3 cathode and the basic idea is a 'free lunch' type amplifier which I can read up on. But how the driver valve, shunt regulator and C4S works is beyond me, I'm afraid. I am going to need a schematic. I haven't been able to find out anything on John Tucker's C4s so I think I am stuck now.



Offline Paul Joppa

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Reply #7 on: December 31, 2012, 07:23:11 AM
Haha! Well, yes, you do have an odd collection of parts!!

I'll start with something about Paramour, though that's not what you really want. Paramour runs the 2A3 at 300v + 60v bias, 50mA, into 4000 ohms. The RCA book shows 250v+45v bias, 60mA, into 2500 ohms. These are two points on a spectrum of possibilities, and are in fact very similar in terms of distortion and power. As you can see, the optimum load impedance is a strong function of the voltage and current.

OK, back to what you have. The first board you showed appears to be John Tucker's shunt regulator for the driver, using one half of the tube as regulator for the other half as driver, with a current source for the driver plate load. I don't have manuals or circuits for that; it was not a Bottlehead product. The "Paraglow II" was the name given to a Bottlehead Paraglow with the Tucker regulator added.

The Paraglow itself has a LOT of versions - it started life as series feed, called "Afterglow" since the associated preamp was the "Foreplay" - yes we are gradually backing off those kinds of names! There were also a few more or less custom designs called "eXcite" at the time. The important point is that they were all direct-coupled, so while the power supply voltage was high, the voltage available for the 2A3 was not. Hence the 2A3 operated at the RCA book value and your EXO-36 is the correct output transformer. The current Bottlehead version of that circuit is the Paramount with 2A3, using the v4.4 C4S/shunt reg board, also known as the "soft-start" board. (That board is available as an upgrade for older Paramounts, with the 5670 driver - in many ways, quite similar to the 6N1P. Naturally I recommend it, since it incorporates lessons learned over the last decade or more.)

The original Afterglow ran 100v on the driver plate, 145v at the 2A3 cathode, and 400v at the 2A3 plate. Later versions ran much higher, as much as 475v, with the driver taking most of that extra voltage. This wide variation in driver voltage has a profound impact on the 2A3 operating point, and is the reason that the v4.4 driver board includes an adjustable driver bias so that the operating point can be optimized even when power line voltage deviates from 120v. Separately, because of the voltage variations, the 2A3 cathode resistor was 2500, 3000, and (currently) 4000 ohms - all aimed at obtaining the same 60mA current!

I'm not sure of the current inventory, but I imagine Bottlehead could scare up copies of the old Paraglow manual and the Tucker upgrade manual, and of course the "soft-start" package has its own manual. I would strongly advise determining the actual voltage available first and adjusting the circuit values accordingly! If it were me, I'd go so far as to build a power supply with regulator (if you are using it) and loading it with a giant resistor to simulate the circuit load, before finalizing the audio portion of the circuit.

Hope that helps.

Paul Joppa


Offline Doc B.

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Reply #8 on: December 31, 2012, 08:09:43 AM
We will have to dig around for a Paraglow manual, as I'm not sure if we still have a copy. I know for sure that we do not have the Tucker shunt reg manual, as that was an Exemplar Audio product, not a Bottlehead one.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline andrewuk

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Reply #9 on: December 31, 2012, 12:12:49 PM
The history of Paraglow et al is interesting and thought provoking, thanks.

60ma is very useful and from there I can begin. I'll check out the PSu but knowing that 360-0-360 with cap, choke cap gives something around 1.4 = H.T. that's relatively okay too.The prob then lies with the input valve and the john Tucker C4s. Surely someone out there has this information; I can't find it anywhere else and on my own I can't reproduce the circuit. Any help?

nearly midnight over here! best wishes, Andrew



Offline Doc B.

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Reply #10 on: December 31, 2012, 12:18:21 PM
AFAIK the tube is a 6N1P. And there is the link to Exemplar Audio below. I'm sure John would be happy to help you with the board.

http://www.exemplaraudio.com/Home.html

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline andrewuk

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Reply #11 on: January 01, 2013, 12:11:45 AM
Thanks, I have emailed John Tucker. I hope he can help.



Offline najo49

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Reply #12 on: January 03, 2013, 02:08:41 PM
Hi I will have in a day or so a set or original paramour more manuals and if you think this would help you. I could scan it and send it that way.

Jann Olsen, [email protected].  Lowther medallion 2 with pm2a./ extended foreplay lll,/EROS phono /Grado ref/ SOTA star Vacuum SME V, /  45 amp direct coupled,c4s,mQ nickel  / paramour  2a3 w MQ iron /Original SEX monos /Jena Cables /heathkit wm6a/ proAc Tablette 50 sig , with push pull


Offline andrewuk

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Reply #13 on: January 03, 2013, 11:15:25 PM
Many thanks Najo49 but its a Paraglow2 I've got - I was wrong; shows what a mess it is that I am going to put right. I now have the Tucker mod papers and the original Paraglow manual. What I would really like now (;-) is a brave discussion on improvements / mods!



Offline RPMac

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Reply #14 on: January 04, 2013, 04:35:58 AM
Andrew, in the original kit, the cathode bypass cap was 220uf, 200VDC...mine let the smoke out. PJ recommended 450VDC or higher.

PJ also did some calculations on the parafeed cap with the MQ iron you have and came up with a value, IIRC, of around 15uf...I put 10uf Obby's in mine(thanks to Grainger).

The other problem I have with mine was with the C4S/sh-reg boards. Turns out the problem was too high voltage feeding the boards caused by high line voltage...125VAC at the wall. Keep an eye on this when you are ready to fire them up.

I think the Paraglows will be well worth you time and effort.