Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Paramount => Topic started by: ssssly on January 21, 2010, 10:09:48 PM
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Any news on when the new soft start shunt board will be available?
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Sorry, the ball is in my court and I haven't done anything on it in the last 2 weeks. It's still high on my priority list; hopefully I'll finalize the experimental PC board design this weekend and get an order in for the experimental parts.
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Any good news to share?
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Keep Paul working..... it's a difficult matter!
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Today I received a package from Mouser - we now have the parts in hand for the prototype Paramount application. (We're building two versions for a listening test comparison before committing to a final design.) We'll stuff the boards on Sunday, and burn them in next week.
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Can we pre-order the soft start shunt boards?
I assume they can be adapted for a Paraglow...PG 2.1?
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The design is for Paramount, and assumes you have the Zener string installed - it's not on the board, though new Zeners will be supplied since the voltage is different. For ParaGlow you'd have to figure a way to add that string, which protects the plate load C4S from excess voltages.
Other than that, the modification consists of stripping everything off the driver tube socket and re-wiring it for the 5670 driver and the new board, so it should work with a ParaGlow or even a Paramour II. (Paramour I does not have enough high voltage current capacity, unless you change the 2A3 operating point current - now we're getting complicated!). For ParaGlow I'd have to look at it again to see if the driver plate voltage should be different from Paramount. Given the long history of ParaGlows and Afterglows, it would probably depend on which power transformer you had, for instance.
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Is the Zener string instillation just installing a string of zeners or will this require further more complicated modifications for instal in to a paramour 2 ish circuit?
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How did the prototype work out?
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The Zeners are a string of five zener diodes that protects the C4S plate load at startup, until the hybrid shunt regulator kicks in. In Paramount they are mounted on a separate solder lug terminal strip; in other applications you would have to locate a new strip somewhere nearby.
One of the designs did not work correctly due to excessive leakage from a capacitor; we are experimenting with a different part. The other design appears to work correctly - first test was this morning, as I did all the soldering last night but was pretty tired and that's not the smart time to test a new design! I'm not going to bother listening until I get the Auricaps installed - we are installing identical Auricaps in both pairs of amps so we can make a consistent comparison.
Tentatively we'll do the first serious listening panel on the 20th of March. If the difference is subtle, the amps will probably go into a more extended comparison test at Doc B's place, where he has the Tape Project tapes and decks as source material.
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Paul, I plan to rebuild my Paraglows to a platform with more room to play...so finding room for the Zener string and boards shouldn't be a problem.
How easy will it be to use the boards to try different drivers? As a direct couple amp, this may be too much for my limited knowledge.
You were right about the 6n1p's losing their "shine"...got some new one...brought the sound stage back into the room.
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Robert,
It has been a while but I bought 10 6N1Ps for $25 delivered a couple of years back. As cheap as they are and as good as they sound they are still a good deal.
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We completed the first part of the comparison of two versions of this new update yesterday. We listened at Richard Riley's since my system is set up for multi-amping and we wanted to hear the amps running more or less full range. Richard has completed some really nice sounding speakers using DIY techniques that emulate the superb designs that Alon Wolf of Magico makes - stacked plywood boxes and solid aluminum front baffles. Without a doubt these were making the best sound I have heard at Richard's place yet.
To cut to the chase, we heard differences between the two variations we were trying. Our theories were not unanimous about what was happening and we need to do a little more break in on one pair of amps to eliminate any possible differences due to that. We will continue to evaluate on the system here at Chateau Bottlehead and make a final decision on which circuit version will go into the update kit in the next couple weeks.
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What is the difference between the two?
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How's the comparison coming along?
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The amps that were not broken in came off the oscillator yesterday so things should now be even between the two. Eileen is having a minor/medium difficulty medical procedure done today so I will probably not be able to do any eval for a day or two.
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Oooohhhhh ... good thoughts, prayers, etc. are headed your way! Hopefully everything is (gonna be) OK. Take care of her - the eval can wait a few days! Best wishes, - Rick.
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Thanks Rick. She came through the procedure in great shape and we should be back in full swing in a few days.
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Be sure and give her a (gentle) hug from all us Bottleheads! Glad to hear everything's A-OK. Now rest up a few days - both of you!
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I, like all subjects of the "Queen" are concerned when she is ill or incapacitated. Give her our very best wishes for a speedy recovery. -Chuck
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Hope the queen is feeling better.
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So how are these suckers sounding?
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A week ago we ran the amps in for several days with a sweep generator. We just cleaned and overhauled the system yesterday to make sure everything was at 100%. This morning we compared the two setups. In the initial comparison a few weeks ago I heard differences in the midrange and the bass and they were identically good on the top end.. So today we rigged my active crossover system setup with the amps playing midwoofers. Even after the break-in I heard the same differences I heard initially, even when trying of a few different types of 5670s we ran. So I think we are a step closer to getting this done.
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Do they both sound good just in different ways or is one substantially better than the other?
Would large modifications be needed to integrate this into a SR-45 circuit?
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The SR45 is not directly coupled, so adding this type of soft start seems needless..
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Once we get the Paramount version out there, I'll take a look at the SR45 - since I want to at least build one. I have a modified design to try out, with DC filaments. I'll also look at other applications. The plan is still to replace all the C4S boards with this new version, eventually. This may take a long time, but it is in the plan.
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Paul:
Per your here I was waiting on these boards for my rebuild/upgrade
"The PT-2 can support a shunt reg driver, copied from the Paramount - anyone who wants to do this should probably wait for the new Paramount driver board with time delay and other goodies; the upgrade kit will be available - might as well convert to the 5670 driver at the same time."
Planned configuration was PT-2, TFA-2004 Nickel, BCP-15 plate chokes and EXO-003. CLCRC full wave schottky rectified power supply with the signal circuit alla the upgrade iron variation with the plate voltage reduced to 275 and current increased to 55mA (also per your suggestion). After reading several posts about the great sonic improvement I also was planning on incorporating the shunt board you have been working on.
Would you suggest this new board for my application or the original SR45 shunt configuration?
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There does seem to be some confusion here.
The PT-2 can deliver 60mA of DC high-voltage current. If you stay with the 50mA 2A3 current used in the Paramour, there is 10mA left, which is enough for a twin-triode shunt regulated driver - we'll have the new board set up for the 5670 in the Paramount so that's a good choice, but others can work.
If you raise the 2A3 current to 55mA, which is more optimal for the 3K impedance, then you have only 5mA left and can't shunt regulate the driver. Also, the BCP-15 cannot support more than 50mA of plate current. So I'd stick with the 50mA/300v of the original Paramour; the increased inductance of the BCP-15 goes a long way to make up for the slightly off-optimum operating point.
The SR45 replaced the 2A3 with a 45, cutting the output power in half. The 45 operates at 250v and needs only 36mA, so there is enough current left over (just barely) to shunt-regulate the entire amp, not just the driver stage. We produced a very limited run of semi-kits a couple years ago for this - semi-kit meaning that there was almost no manual and not much developmental testing. It was intended for advanced experimenters. We never saw enough potential sales to justify the full development effort, but we liked the sound so much we wanted to make something available to at least a few.
I posted a few minutes ago in the other thread, sorry for the confusion and I hope this note helps make sense of my other one!
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Sorry for being so impatient but I was wondering what the status is on the soft start shut upgrade for the Paramounts?
Thanks!
Dave
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The circuit is done. It's just a matter of getting a batch of parts in and writing the manual. Probably won't happen until the Stereomour manual is done, but the "final proof-of-concept" prototypes tested OK this week so that shouldn't take more than a couple-three weeks - assuming Doc B can get downstairs pretty soon!
I'm fairly sure the initial product will be the Paramount replacement board, including conversion to a 5670/2C51/396A driver tube. I haven't talked to Doc B about the detailed process, but I'd expect the Paramount to be revised accordingly - the main issue is revising the manual, which is WAY more work than you might think.
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For a non-direct coupled 2A3, like my Paramours this isn't a suggested improvement, right?
That, of course, doesn't address if the power supply can support it.
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If the power supply can support it (i.e. Paramour IIs with the PT-2 power transformer) then it is a major upgrade because it would add shunt regulation to the driver tube. We are not planning a manual for that at first.
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I'm a Paramour 1. Well my amps are. The jury is still out on me.
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I am not overly concerned about the soft start for the Paramounts or even upgrading the sound, I have a hard time imagining them sounding any better than they do. But one thing I remember reading is that the new board would drop the plate voltage on the 12at7 from 350 to 300V. Certainly not a huge deal but anything to extend tube life on my beloved Mullards even by a little. Do I remember correctly?
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You can drop the plate voltage yourself, if you like. Replace the two 174k resistors on each green board with 150k resistors (use Vishay PR02 resistors). I would also put a little clip on heatsink on the transistor Q2 on the B side of each board (the side with less components). If you have an MJE-350 there now, consider replacing it with an MJE5731A, which will be easier to cool.
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It is kind of confusing.
The shunt regulated power supply for the Paramount driver is currently 350 volts. It is protected with a string of Zener diodes, until the shunt regulator tube warms up. In the new design there is a change that exposes the plate load transistor to a possibly greater voltage during the start-up transient, so we had to drop the regulated voltage to 300 volts. This is the effect of the resistor change PB describes. The shunt regulator tube now also has 300 volts on it, so it operates a bit more conservatively.
In the current production, the driver uses either an LED or a shunt-regulator chip to provide fixed bias without electrolytic bypass capacitors. However, that makes the range of actual plate voltage wider than would be the case with ordinary cathode resistor bias. That range is typically 140-220 volts, but can vary a lot with different tubes. There are two problems:
1) With the lower regulated voltage, some 12AT7s will run out of voltage headroom (compliance) when driving a 300B
2) The direct-coupled 2A3 is very sensitive to power line voltage variations, and the driver plate voltage should really be optimized for the particular power line voltage in your home. Even at the design value of 120vRMS from the power line, different tubes will have different plate voltages and can be uncomfortably off optimum.
For these reasons the new board has an adjustable bias voltage, so that the driver plate voltage can be set precisely. Normally it would be around 175-200v, same as the current design - only the C4S headroom (compliance) has been reduced, not the actual driver plate voltage. The adjustable bias arrangement we have implemented will not permit a bias below 2.5v, so the 12AT7 has too much gain and we went to the 5670 - which is also more linear and widely available in premium versions. The adjustable bias does make it easier to use a different tube; I plan to change my personal amps over to 6SN7s to reduce the excess gain.
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Sounds like modding a normal Paramount for 300V on the regulator would also require changing the 237 ohm R1 on the driver CCS to more like 250 ohms?
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I'm eagerly awaiting this upgrade - mostly to give me something to mess with.
PJ: Is the 5670/2C51/396A confirmed in the design? Basically, is it safe for me to source a pair of these tubes in anticipation of the product release?
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PJ: Is the 5670/2C51/396A confirmed in the design? Basically, is it safe for me to source a pair of these tubes in anticipation of the product release?
Unless Doc B makes a sudden shift in focus, yes it is the design choice. Even if it weren't, it would be easy to implement this tube.
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And once up and running, time for EML tubes :) Should there be any issues after this modification?
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Doc or PJ, would you happen to have any new updates on when the soft start shunt update might be available? I have kind of been holding off on constructing my 2A3 Paramounts.
Thanks!
Dave
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Another month gone and hopefully the move is making progress. How's it coming with the boards? :)
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I picked up a nice pair of 5670s and now jonesing for this product release.
PJ - any updates you can share on release timing or issues? I think a few of us are keenly interested in learning more...
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We are concentrating on getting the Stereomour out right now, which has fallen a little behind due to unforseen circumstances. Once we get the first of those kits out in the next three or so weeks, we will move on to the soft start update and some of the other long awaited projects.
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Any update on the schedule for this long waited circuit? Thank you.
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A bump for interested parties. Hopefully you guys are moved in and getting caught up :)
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Still moving (a huge job with several unforseen delays), and still getting ready for RMAF. The soft start upgrade (along with the power cord kit we owe early Stereomour purchasers) is the #1 priority when we get back from RMAF.
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PJ has sent the final revision of the new Paramount soft start PC board to me and we will be ordering some prototype boards to use for the manual photographs shortly. Hope to be ready to start taking orders in a week or two.
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Nice! Thanks Doc!
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Monthly bump. I know you all are working hard over there :)
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Waiting for the last resistor to show up in order to schedule the photo shoot. Seems to be taking forever.
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OK, prototype is up and running nicely. Eileen is costing the parts today, and I have the assembly photos processed and ready to put into the manual. Hope to be able to take orders for the retrofit online in the next few days, and incorporate the new circuit into Paramount 1.1 in the next few weeks.
This mod is fairly extensive. It removes the existing PC board over the 12AT7 socket, the 12AT7, the nine pin socket and the terminal strips around the 9 pin socket. It will include a new, bigger and slightly more complex PC board with soft start function and the parts to stuff it, heatsinks for the active load power transistors, a new nine pin socket, new standoffs, mounting hardware and t-strips, a new beefier zener string and 5670 tube - all X 2, for the pair of monoblocks.
Do you need it in your Paramounts?
Here's what it does, to help you decide -
Firstly the new driver PC board has a soft start function. This delays the B+ to the plate of the driver tube for about 30 seconds at startup. I should note here that once fired up, the amp will need to sit for about 20 minutes after you turn it off for the circuit to "reset" itself and function with the soft start. This was added in response to a user who was using EML 2A3s in the direct coupled 2A3 version of Paramount and experiencing 2A3s arcing at startup when hit with that driver plate supply B+ before the filament could heat up. This new soft start circuit will resolve that issue. Off the top of my head we have not heard of anyone experiencing this arcing issue with anything other than the EML 2A3 and the long discontinued AVVT 2A3s. And this should not be an issue in the cap coupled 300B version. However the soft start may be useful in extending the lifetime of other tubes as well.
Secondly, the zener diode string has been beefed up. The original string worked fine unless you goofed something up in the build that overstressed it. The new string is much more tolerant of errant solder joints, miswires, etc. The circuit has been stress tested by me personally - 'nuff said.
The MJE5731As on the new PC board now sport heat sinks to extend their reliability as well.
One of the most noticeable changes is that we have gone to a 5670/2C51/WE396A tube as the driver. Why? Partly because a lot of folks found that the 12AT7 had to much gain in their system which led to hair trigger volume controls and a bit more transmission of the noise floor from front end equipment than they liked. The 5670 has a mu of 33 as opposed to the mu of 60 of the 12AT7. The 5670 is also a very sweet sounding, particularly linear tube, that we feel is step up sonically from the typical 12AT7. There's enough variety of brands to make tube rolling interesting and it is not prohibitively expensive. Even if you are running your Paramount in 300B mode like I do, you may find the 5670 the most compelling reason to upgrade your Paramounts to the new setup.
OK, the next thing you want to know is the price, right? We're gonna bite the bullet for a couple weeks and offer an introductory price of $199 for the retrofit kit. On January 1, 2011 the regular price of $249 will take effect. I'll get an order page up in the next day or two, or you can call Eileen today at 206-451-4275 to order.
I think at this point that we will be able to hold the price of the upcoming Paramount 1.1 kit that includes this upgrade to within $50 of the current price. We have some of the current version kit parts in stock, and as a little incentive to move them out we will offer six Paramount kits in the current 1.0 version (12AT7 driver, no soft start) for $100 off the regular price. That means you can get the current version of the Paramount 2A3 kit for $1349 and the current version of the Paramount 300B kit for $1399. That deal is only good until January 1st or until we sell all six kits, which ever comes first, and you will need to call Eileen at 206-451-4275 or email her at [email protected] to get this special price.
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The 5670 is also a very sweet sounding, particularly linear tube, that we feel is step up sonically from the typical 12AT7
'Nough said. I'll order three pairs. Price is per pair, right?
I'm learning how to use FPE and my idea is to eventually move all my BH gear to Tube Repro-like chassises. What a good opportunity to change to the soft start shunts!
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Yes, price is for a kit to upgrade a pair of amps. We'll put your order at the top of the list. I should have the kit ready in a few days.
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Great news - even though I do not own Paramounts [at least not yet], the update will work with my Paraglows, albeit with a few adjustments, yes?
If so, I'll order a kit as soon as they are available. I've actually already ordered my first pair of 5670's to roll, it would be a shame if they didn't make it into an amp.
Bryon
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Me too! One pair please. You can put the kit in with my custom Eros when finished to save on shipping :) I'll email Eileen also.
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Great news - even though I do not own Paramounts [at least not yet], the update will work with my Paraglows, albeit with a few adjustments, yes?
If so, I'll order a kit as soon as they are available. I've actually already ordered my first pair of 5670's to roll, it would be a shame if they didn't make it into an amp.
Bryon
Will these work for a Paraglow upgrade?
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The kit could be made to work. We are not currently publishing step by step instructions for this, I am writing instructions specific to the original Paramount first. So for now at least one would have to do some figuring on their own to adapt it to other designs.
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Can't learn any sooner...order on the way.
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Doc
Maybe you or PJ could post a list of kits that this will work with. From my discussion with PJ about this I know for instance that this will not work for PMour 1s because the power transformer doesn't have the headroom. Could be isolated due to the older tranny design but folks my be more apt to adopt this if at least they knew if it can work with what they have. I know for myself, if I know something can work I am more likely to buy it and then figure it out.
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The manual that I am currently writing is specifically for retrofitting this kit into the current version of the Paramount amps. The next manual I plan to write is one that will be specifically about building the new Paramount V1.1 which will incorporate the soft start shunt regulator into its construction. So the safest list I can give today has just one entry, as it comes the kit parts and instructions are specifically for Paramount. But one could change a few parts values and use it in a variety of applications, in fact the board has been designed as a sort of future universal replacement for a lot of our kits to aid our inventory control. I'm going to let PJ weigh in here on more specifics.
It is difficult for us to know the comfort level of our customers when it comes to how much they are willing to figure out on their own. I get a certain number of folks who ask for very highly documented instructions for one-off customizations of kits, and that is unfortunately not something I really have the time to do these days. That's a major reason for the existence of this forum. As a community we can all work to develop enough info for someone to develop these kinds of special projects that might be tackled by just a few people.
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The forum is no doubt one of the greatest assets to this hobby. And your post is actually more or less what I was talking about. Was thinking more a list of which kits have power transformers capable of the extra current draw. And then let those of us crazy enough to dismantle perfectly good sounding amps figure out the rest via the forum.
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Maybe you or PJ could post a list of kits that this will work with. ...
I'll work on it, but understand, there are nine other kits (counting the discontinued ones) and some of them existed in several different forms. Not to mention that many of them have been modified by their owners! I'll see what I can come up with.
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In general a kit that already has a shunt reg and active loads like the upgrade that JT did for the Paraglow would be able to use this kit once modified for the operating conditions. That would include the shunt reg 45 that we did as a limited run - adjusted of course for the 6CM7 tube rather than the 5670. And one could also use the boards themselves in Eros and FPIII.
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Funny thing is I'm thinking backwards than the rest. When I rebuild my Parabees and my Excites I will use the driver section from the Paramounts!
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I can't quite remember what the circuits for all the 45 variants we came up with over the years were called. Was the Excite a monkey on a stick circuit, where we put the driver tube and its active load under the cathode of the 45? If it is you will want to change it to something more like the Paramount 2A3 - or if you could do the SR45 circuit with some adjustments.
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This is a first cut; I'll try to edit it as corrections or other questions crop up.
Original SEX
Based on the DeYoung power transformer version. Should be possible using the existing tube (no 5670) but mounting the board and routing the wiring will require some creativity.
I would recommend upgrading to the TFA-204 output transformer, removing the feedback loop, and changing to dual bias resistors and bypass caps in teh output stage, as long as you are under the hood.
Current (stereo) SEX
Not applicable.
Afterglow
With the DeYoung power transformer, you cannot get to the requisite 100v on the plate unless you change the driver to a 6CG7 or similar low-gain tube. Actual desired voltage will depend on the actual power voltage in your house
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Nope
The Excites were a 45 version of the Paraglow. The circuit was very similar to the one published in Valve known aka Simple 45. Direct coupled, C4Sed 45 with PGP 8.1s The article circuit used 5965s(?) paralleled. The BH version used 6N1Ps and there was a II version by JT that SRed the 6N1P.
The OP points were classic RCA's 45 OP.
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The oldest designs went through the most changes - this was before we started to use version I, II, III designations for major revisions. This applies to Original S.E.X., AfterGlow, eXcite, B-Glow, and to a lesser extent the parafeed amps ParaSEX, ParaGlow, and ParaBee.
I started to write down some of the changes I remembered, but the post got hopelessly complicated as I kept remembering more changes and revisions. Suffice it to say that, when considering changes to any of these older products, you may have to do some sleuthing to uncover the exact configuration!
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Any shipping date set for this update?
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Any shipping date set for this update?
Just waiting for some parts to show up and we'll be shipping.
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Woo Hoo! kit arrived today, I know what I'll be doing this weekend.
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"I'm so excited, and I just can't hide it....." Not that it's playing but if you can't tell, I'm looking forward to this build ;)