Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Topic started by: andrewuk on December 30, 2012, 11:36:56 AM
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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
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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.
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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
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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!
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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
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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.
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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.
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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.
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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.
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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
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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 (http://www.exemplaraudio.com/Home.html)
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Thanks, I have emailed John Tucker. I hope he can help.
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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.
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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!
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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.
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That's certainly to be taken into account, thanks. Could I damage the C4S/sh-reg boards in this way? I have the Tucker upgrade circuit.
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What I would really like now (;-) is a brave discussion on improvements / mods!
I'd do your best to get the amps working in stock form first, then consider parts swapping. Based on the collection of parts involved, I wouldn't want to add more variables to the equation.
-PB
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One thing I recall about John's boards was that if you run the trimpot all the way to the end of it's travel before installing it you can blow the board. Be sure to use meter to measure across the pot (one end leg is connected to the middle leg on the PC board if I remember correctly, so measure from the middle leg to the leg that it does not connect to) before installing it and set it to approximately the middle of its range. I don't recall the value of the pot, but if it's a 100K, set it around 50K, if it's 250K set it to about 100K, etc. The idea is you want to make sure it isn't close to zero ohms.
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Andrew, have you gotten the information from Doc and John?
Paul, I think he is already past the "original" stock design that will corrolate to the original manual he will get from Doc. If he also has the original C4S boards (non-shunt regulated board) and the 5965, you are correct to build it stock by the manual first.
Doc, it is a 100K pot.
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My thoughts on improvements are in my longer post, above. To my mind the most important is to get the operating points right, meaning you have to get it running first, then check voltages, and from there adjust the driver bias to get the right plate voltage, and then adjust the 2A3 cathode resistor to get the right current.
Direct coupling is a pain in the backside, no question. If it didn't sound good, nobody would do it!
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Progress is slow - I'm back at work so other things must take up time.
I thought I'd knock up a couple of Camille CCS just incase things go wrong with the Tucker ParaglowMk2 and I can revert to Paraglowmk1. I've already found two very simple and fundamental probs with how the previous owner was wiring the amps up - almost too simple to see! That however is dealt with.
Back to the CCS...
Consider the Paraglow mk1's CCS (and also the Active SEXamp CCS in 'Valve' many moons ago.) I was soldering away merrily using 'verobard' and I thought, 'just a minute ...'
I have a few copies of another US magazine in which a contributor is using a Camille CCS and he reverses the pin outs of the two transistors (a 2N2097 equivalent (PNP) and MJE 350) such that the 350's emitter is down to the valve's anode and the 2907's collector is joined to the HT via a 100 Ohms current setting resistor. Surely this is a mistake! If Paraglow's CCS works then the other cannot!?
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I've just found another on DiYAudio ... Again, the 2N2097's collector via the current setting resistor goes up to the HT of the circuit and the emitter of the 350 goes to the anode of the driver valve. The plot (for me) thickens! or in other words ... 'I don't understand!'
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It would probably help to post links to what you see.
For example, I found this image off of DIY audio that is consistent with our schematics:
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.diyaudio.com%2Fforums%2Fattachments%2Ftubes-valves%2F26720d1083627681-some-questions-about-c4s-ccs-adjustment-12b4a-active-loaded-linestage-small-.gif&hash=b98bc23c938371f9e94d78d7b1aa5c7d38c7e212)
In C4S construction, the collector always "feeds" the circuit...
There might just be something done differently in the drawing conventions that is causing the mixup.
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Okay, I don't know how to do this but I'll try and take jpegs and post a picture. Though surely the paraglowmk1 or SEXamp C4s is well known and if you just picture that with the transistors reversed as I explained ... I'll see what I can do.
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Aha! the posted schematic that I saw on DiYAudio gets corrected quite quickly but as far as I know the other example I came across is a very good (otherwise) looking example of a parafeed 46 SE amp in 'Sound Practices' in 1999 by a chap called Ross Lahlum. His is a great article and I built a couple of his CCS' and managed to lose them so I never got to fin dout how they sounded...ahemmmm (they are somewhere in this room!) last year. My experiments with 46s and then the 47s never got changed to anything unlike a 'Bugle' amp (i.e. 5751 as SRPP driving output triode, if I remember, My 47s are ancient globes - they look great!).
So, having sorted that out - onwards!
I'll look at the PSU now and see what I get with (and without) the shunt regulated power supply boards.
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Here are the voltages on my Paraglow II with Tucker shunt/reg boards and 6N1P.
All Magnequest iron
PGP 8.1 power tfx & RGC-6 chokes
EXO-03 plate choke & EXO-36 opt
2A3 cathode resister 3.3K
121.3VAC in
378VAC out
483VDC
471VDC after CLC
on 2A3
452VDC plate
202VDC cathode
158VDC grid
on 6N1P
B1 158VDC plate
B3 2.45VDC cathode (332 R)
B6 224.5VDC plate
B8 5.8VDC
Only resistance out of tolerance were the B+ windings
140 & 149 where the book said 200.
PJ, do you see any adjustments I need to make?
Thanks, Robert
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Wow - that is really sweet - unbelievably close to the ideal!
No adjustments. The 200 ohms spec is left over from the deYoung power transformer - you have the Magnequest PGP-8 so it's no surprise the resistance is different. Tuckers spec for B6 was 215 but I like your 225 better - keep it there.
Check the B1 voltage occasionally, once a year perhaps? It will increase as the driver tube ages. When it drifts to 175v the tube should be replaced. Controlling that voltage is the critical difficulty with direct coupling; it would be preferable to keep it in the range 145-175v. You are almost exactly at the center of that range, so no worries.
The high voltage exceeds the power supply capacitor rating of 450 volts. (This is another consequence of changing the power transformer.) I don't recall many problems with that, but the one or two in my dim recollection were on older amps. If this amp has seen a lot of hours, it might be prudent to replace them. Finding a cap with a higher voltage spec that also fits mechanically will be difficult, you may have to get the same 450v and hope the quality has not deteriorated. Difficult decision between preventive maintenance and "if it ain't broke, don't fix it!" ...
Hope that's helpful!
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Thanks Paul, but the credit for "ideal" has to go to the crew at Bottlehead...I can just solder and follow instructions.
Question on power supply caps. I have some CDE unl series 30uF 600V and 35uF 500V caps...can they work for the power supply? I already replaced the cathode bypass caps (had one to fail) with these. A single would be a tight fit, but if I need to parallel to increase the uF, that will be the problem with these amps. This question would be for my Parabee's also.
Those voltages were on my "good" amp that I got out of storage yesterday to make the measurements. The other amp will take a little more work, but I have some measurements before I put them in storage.
Amp #2
124VAC
388VAC out
486VDC
472VDC after CLC
on 2A3
448VDC plate
219VDC cathode
178VDC grid
on 6N1P
B1 178VDC plate
B3 2.44VDC cathode (332 R)
B6 227VDC plate
B8 6.97VDC
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The UNL caps would be great if you can fit them in; I think since you have a 10-henry choke in the power supply that 30uF is enough. Google for the data sheet to see the voltage/lifetime tradeoff (very interesting) - figure at least 60 degrees C under the hood. I'd go for the 600v rating, especially on the first cap of the filter.
It looks like the B1 voltage is a little high. If the 6N1P is old, replace it and see if the voltage comes down; you want around 150v with a new tube. We've seen inconsistent service life with 6N1Ps; look for the older Svetlana 6N1P-EV if you can find them at a reasonable price.
You can trim the regulated voltage (B6) a little higher as an alternative, but if you go too far the B8 voltage goes high and destroys the reg chip - serious pain in the butt! B6 must be at least 50 volts greater than B1 to avoid premature clipping of the driver. Unfortunately I don't know the resistor values on the board so I can't estimate a reasonable value, but 250v will likely be OK.
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Its odd, I am taking this very slow ... as I think the geezer wot I bought this off was doing. I am very busy at work and have several projects on the go - the icing on the cake is this one - but with a 27 / 47 tube pre here and ressurecting my 833s there; the GM70s have been in the shed for too long and those sweet el84PPs ... As my beloved has started redecorating after some serious house readjustments I don't get to play and listen and I'm in a bit of a mess. Sorting it all out is fun but frustrating. Of ate I hav been listening to my rebuilt ESS AMT1Ds with solid state amplification - Heresy!