Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: Doc B. on November 04, 2009, 05:21:01 AM

Title: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 04, 2009, 05:21:01 AM
PJ and I had a brainstorming session yesterday. One of the more fruitful storms was a neat constant current source circuit that PJ had cooked up. The most unique feature is that it is designed to compensate for the battery B+ supply voltage dropping over time as the batteries drain with use.

It's a fairly simple circuit that we easily fit onto the same SRC4S PC board that we use in the Foreplay III Extended upgrade kit. You just stuff a board with about 10 components, add 6 wires and install it in place of the 4K ohm plate resistors. The board is very lightweight so we just let the prototype hang by the connecting wires. There are mounting holes in the board, and I'm sure one could use one hole to attach the board to a standoff that could thread onto one of the tube socket mounting screws.

I had mentioned in another thread that I tried a standard C4S in the Quickie with no real improvement, and not the best bass. Stupid me! I was using a Quickie that had the Speco transformer mod for high impedance headphones, which is about 3dB down at 80Hz, as a line stage. And I was using some cheapo cables that seemed to make the light bass even worse. PJ also pointed out that the C4S will not compensate for the drop in B+ voltage as the battries drain, so it's not the best choice for this particular circuit.

With this new current source installed in a non-Speco'd Quickie and using decent cables there was a "Whoa!" reaction from all three of us when we compared against a stock Quickie. Gain was a little higher with the PJCCS in place so we compensated our listening level accordingly. At the same level as the stock Quickie the improvement in image size and location, and the improvement in resolution from the modded Quickie was very audible. I also noted that the bass seemed to show more harmonic structure. Since a battery power supply is dead quiet already this isn't due to the high power supply noise rejection of the CCS. So the sonic improvement seems due to the distortion being lower at any given output level.

This went together so well and so easily that it became an official kit during the cocktail hour last night. We will sell a kit of parts and simple one page instructions for $35.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Grainger49 on November 04, 2009, 05:28:22 AM
First, a real tip-'o-the-hat to the crew for concocting a new product so quickly.

Reading the post I wondered if there was lubrication during the design stage but you mentioned that cocktail hour followed.  I guess I was wrong.

I'm going to smoke test a BH reg board this afternoon.   There will be more.

Congratulations on a truly "Quick Delivery."
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: booangler on November 04, 2009, 06:54:13 AM
Out Stinkin' Standing,

Can't wait to order another quickie and the board. Is there going to be a package deal?

Alan
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Len on November 04, 2009, 07:09:40 AM
I was using a Quickie that had the Speco transformer mod for high impedance headphones, which is about 3dB down at 80Hz, as a line stage.

Tres cool!

You know I'm in. The Hammonds will go on the headphone amp.

I'll be using the PJCCS in my low pass filter Quickie that needs 500 ohm output impedance, so I'm using the Specos there too. Do you know of a high quality 4K:500 output transformer or have any plans for working with Mikey on one?
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 04, 2009, 07:15:27 AM
Quote
Is there going to be a package deal?
\


The price is already so low that we make only a tiny profit on these as it is, and I don't think we are able to offer a lower price for the combination. But of course one would save on shipping by ordering them together. Give me a little time and I will get the order buttons up on the website. Meantime, if anyone would like to order a PJCCS kit call or email Eileen - 360-697-1936 or queen at bottlehead dot com. It will take a few days to get the assembly instructions completed and then we should be able to ship
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Dr. Toobz on November 04, 2009, 09:31:39 AM
So, would these be an improvement over plate chokes? I'm using the Quickie with Specos as a headphone amp, and don't get the impression that current sources would make much of a difference if the Specos were still being used as OPT's. As a proper preamp, it sounds like they would. Correct?
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: ashok on November 04, 2009, 10:01:56 AM
Give me a little time and I will get the order buttons up on the website.

Hi Doc,

While you are adding the order button for the PJCCS, could you also put in a button for ordering the Seduction base with the Quickie?

Thank you,

Ashok
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 04, 2009, 10:39:03 AM
Quote
could you also put in a button for ordering the Seduction base with the Quickie?

Yes, thanks for reminding me!
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 04, 2009, 11:34:32 AM
... I'm using the Specos there too. Do you know of a high quality 4K:500 output transformer or have any plans for working with Mikey on one?
Yes, I have asked Mike about the B7 parafeed line output, in either 5K or 8K primary, 500CT secondary (with a 125 ohm tap available). It would cover a wide range of headphones as well as being a decent driver of 500 ohm loads, balanced or single ended. If you have the bucks, this can even be stacked with 80% nickel laminations for extremely high inductance and low distortion.

I am working on a set of operating points and circuits for alternative plate loads and transformer outputs. Mostly it's just compiling the many ideas that have shown up here on the forum, and tweaking the operating conditions for them.

More on that when I have more to offer, but meanwhile it looks like the optimizing comes down to two special cases:

1) maximum power output per volt of input occurs when the load equals the plate resistance, i.e. a 4K plate load. Operating point is approximately 25v at 2mA (the other 11 volts is dropped in the plate load and the 1K cathode bias resistor.)

2) Maximum power output for a given plate voltage occurs when the load impedance is twice the plate resistance, i.e. an 8K load. At 25 volts as before, the plate current would be 1.2mA (cathode resistor about 2K)
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 05, 2009, 04:54:18 AM
PJ asked me to mention that since this current source compensates for the B+ changing as the battery runs down PJCCS stands for the Paul Joppa Compensating Current Source.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: booangler on November 05, 2009, 06:16:47 AM
PJ asked me to mention that since this current source compensates for the B+ changing as the battery runs down PJCCS stands for the Paul Joppa Compensating Current Source.

All Hail

The Paul Joppa Compensating Current Source


I can't wait to try it... come on Hanukkah

Alan

Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: John Swenson on November 12, 2009, 05:37:27 PM
Hi PJ,
I'm not quite sure of the reason for a special CCS here. A regular CCS should automatically provide the needed voltage drop necessary to present the plate with the needed voltage for the OP. For a standard C4S the only thing I can think of that would cause any change depending on the B+ would be the current in the LED string that would make a slight change in the voltage across the current set resistor which would of course cause a small change in the plate current.

Of course you might want to go with a completely different CCS design in order to get lower minimum voltage drop across the CCS, but even so I still don't see why a regular CCS design won't work.

Not to disparage the design, I just don't see why a regular CCS design wouldn't work.

What am I missing?

John S.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 12, 2009, 07:59:10 PM
When the battery is fresh, the B+ is 36 volts and the plate voltage is about 28 volts, bias voltage 2 volts at 2mA plate current. That leaves 8 volts compliance for the plate to swing  positive and negative.   

But an alkaline cell voltage drops linearly as it is discharged, with end-of-life voltage about 2/3 of the initial voltage, i.e. 24 volts for the Quickie B+. By the time the battery drops to 29 or 30 volts, i.e. half its energy has been used, the remaining compliance of 1-2 volts is not even enough to keep the current source running, much less allow for output voltage swings.

By dropping the current to 1.3mA or so when the battery drops to 24 volts, the plate voltage will drop, to maybe 18 volts. That leaves 6 volts compliance and the preamp continues to work.

Of course a regular current source will work well if you use NiMH or NiCd batteries, which have a fairly constant voltage throughout their discharge cycle.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Dr. Toobz on November 13, 2009, 06:42:08 AM
Is it worth bothering with these if we've already loaded the plates with chokes, though? (I mean, in place of the chokes - are CCS's better for sound quality?).
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Koda on November 13, 2009, 07:14:49 AM
Here is another "what if" question.
Is it worth bothering with these if we've already loaded the plates with chokes, though? (I mean, in place of the chokes - are CCS's better for sound quality?).
What if Nicad's were used for power, would there be an advantage of the PJCCS over a choke?
I can almost hear the response of "try it and let us know" but if it is the same and I already have the chokes in place...
  Thanks, and I really do apreciate the help and education everyone provides!
               K.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 13, 2009, 08:07:25 AM
I guess the best you can do at this point is compare my description of what I hear against what you hear, as I have not tried the chokes. I heard much better definition of notes and the image became much more clear and realistic in terms of proportion and sense of depth. A hunch is that it is probably doing more good stuff since the impedance of the choke is lower than the current source, and it appears that what we are hearing is primarily due to a lowering of distortion at any given level vs. the stock setup - a result of the high impedance load.

I have been forming a theory over the past 15 years that a lot of folks prefer a particular change to a tube circuit because it may help the bottom end or the image or whatever and doesn't change the treble, and part of the reason they went to tubes was to smooth out an edgy digital setup. IME a CCS will make the treble more quick and concise than a plate choke. Since a lot of listeners do use digital front ends, that change in the treble definition that I consider an improvement may not be to their taste because it may tend not to help downplay any digital mid-treble edge coming from upstream.

That is perhaps a circuitous route to say that I think a CCS often does more good for the sound than a choke, and that any problems that are upstream should be addressed upstream rather than trying to iron them out them after the fact. BUT I'm also saying YMMV.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 13, 2009, 11:05:05 AM
...
I can almost hear the response of "try it and let us know" ...
I see I may have been too consistent in my responses lately ...  :^)  It's not an experiment I have done. But here's one I did do:

Some years ago I built an experimental parafeed preamp with a 6BL7. I had some tapped chokes on hand, whose basic inductance at the tap was about what I think is right for those impedances. end to end, I could get 20% more inductance. So I added a second choke per channel and wired it all up to a switch - I could select 100%, 120%, 220%, and 240% of the "right" inductance. Sure enough, every increase of inductance was an improvement in the sound. Doc B wanted to swap in a C4S, but that would have changed the operating point (plate voltage specifically), making it hard to interpret the result reliably, and I never got around to resolving that issue.

I conclude more impedance is better. Now the PJCCS is not a cascode (it would rob too much of the limited available compliance voltage) so it is not as high an impedance as a C4S. I don't know the Early voltage of the MJE350, but assuming it's around 50v (typical for transistors) the dynamic impedance would be 25K ohms. A 150 henry choke is 19K at 20Hz, 190K at 200Hz, and 1.9Meg at 2kHz unless its capacitance is dominant at the frequency. So it's possible the choke would sound better than the current source.

Title: PJCCS listed in Bottlehead store
Post by: Doc B. on November 19, 2009, 10:03:12 AM
OK folks, the manual is getting written today and the order button is ready to push!

http://www.bottlehead.com/store.php?crn=220&rn=441&action=show_detail (http://www.bottlehead.com/store.php?crn=220&rn=441&action=show_detail)

(http://www.bottlehead.com/sc_images/products/441_large_image.jpg)
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: booangler on November 19, 2009, 10:34:13 AM
Hot Damn!!!
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 24, 2009, 08:45:56 AM
Got behind a little, but I finished the PJCCS manual yesterday and tomorrow we will be getting out all the PJCCSs that have been ordered so far. Thanks for those orders!
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Wardsweb on November 24, 2009, 08:59:19 AM
Perfect timing...I placed an order about an hour ago.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: BNAL on November 24, 2009, 10:57:15 AM
I assume you can use the PJCCS with the headphone design?
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Len on November 24, 2009, 11:52:11 AM
I assume you can use the PJCCS with the headphone design?


I think I posted on the old forum but can't find it right now. Anyhow, the problem is the battery voltage will drop as they age. Using the fixed bias of an LED in the cathode will cause an exaggerated change in tube current as the battery ages; the cathode resistor provides negative feedback at DC to maintain the appropriate operating point.

A quick look at the curves shows the plate current dropping from 2.5mA to 1.0mA as the battery drops from 36v to 24v.

A reasonable solution would be to use a current source to replace the plate load - that way the tube maintains a constant operating point, and operation will cease suddenly when the battery no longer provides sufficient compliance for the current source. I'd suggest 1.5mA as a good value to use. Note this will not work well for headphone operation where a substantial output voltage is going to be needed, unless you also add more battery voltage. Now this is starting to get complicated!

Would the above long post apply with the PJCCS, too?

It's probably a moot issue, since many of us will be adding more battery power anyway (a milliwatt power binge!)
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 24, 2009, 12:34:38 PM
I assume you can use the PJCCS with the headphone design?
Yes, it is designed to adjust the current as the battery ages.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 24, 2009, 12:38:21 PM
...

...

Would the above long post apply with the PJCCS, too?...
No, that post is old - it's actually what started me thinking about a self-adjusting current source. The PJCCS should work well and give fairly good battery life whether implemented as a preamp or as a headpone amp with output transformer.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Len on November 24, 2009, 01:26:04 PM
...

...

Would the above long post apply with the PJCCS, too?...
No, that post is old - it's actually what started me thinking about a self-adjusting current source. The PJCCS should work well and give fairly good battery life whether implemented as a preamp or as a headpone amp with output transformer.

Cool!

Can it work with higher voltage?

Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Wanderer on November 24, 2009, 02:20:52 PM
Does the PJCCS offer the same gain increase as the Hammond choke modification?

I have a choke mod Quickie and can't give up a db of gain.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 24, 2009, 07:52:32 PM
Does the PJCCS offer the same gain increase as the Hammond choke modification?

I have a choke mod Quickie and can't give up a db of gain.
Yes.  :^)
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: cpaul on November 09, 2010, 06:29:31 PM
I'm having trouble with wiring up the PJCCS I just received.  The PCB is a bit different from the one pictured in the manual and some solder points are missing/not the same.  The partially stuffed board is here:  

http://picasaweb.google.com/103078014592468973736/Bottlehead#5537786106126040610

In short, p.13 talks about soldering a wire from points bA to bB with an "S" shaped wire.  My board has no such points, though it has all other solder points in different orientations from the manual.  I can't make sense of the solder points that DO exist to match them to the board as represented in the manual.  Can anyone help me figure out what points are the bA and bB on my board?

Thanks.

Edit:  Hnmm.  I can't seem to get the pics to post, so I've tried just posting the link.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Wanderer on November 10, 2010, 06:12:00 AM
I am currently working on a PJCCS myself. Follows the manual just fine.

The board you have looks nothing like mine. I am thinking you may have gotten the wrong board with your kit. 

Call the Queen - bet she needs to ship you a new/correct board. 
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 10, 2010, 06:48:41 AM
Wanderer is correct, there are two board designs. You have the older, more narrow one, but the Quickie manual is written for the newer version, developed for the Eros.

We are in the process of transitioning all uses to the new board, but that takes time as each manual must be modified and new pictures taken for it. Actually, there is a slight modification of the Eros board that will appear with the Paramount driver upgrade - this will be Version 4.4. Fortunately it is so similar to the current Eros/Quickie board that there should be no need to modify those manuals! All this work is intended to make the boards flexible enough for many different applications - they are MUCH less costly in higher volumes.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: cpaul on November 10, 2010, 07:32:21 AM
Thanks, guys.  In looking it over, I just assumed though different, the two boards could both be wired to work.  The only issues I figured I'd have are the "s-shaped" wire connector between bA and bB and the connections to the quickie circuit.  If there is a way to do this without the Queen having to send a replacement board, I'm happy to take instructions for how to wire this board properly.  If all traces are visible on the board I have, I may be able to figure it out from the manual photos and schematic.  If I can't work it out, I'll call her.

Oh, note too that the transistors I got don't have the metal ground plate on the back for orientation.  I assumed the side opposite the one with writing was the same as the metal plate (per most transistors I've used).  If anyone thinks I've got it wrong, please let me know.

Carl
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Grainger49 on November 10, 2010, 07:46:33 AM
Does your board look like the one in the first post?  If so, and the instructions are written with the new board nomenclature you are in need of better, more specific instructions. 

Am I right?

I'm having trouble with wiring up the PJCCS I just received.  The PCB is a bit different from the one pictured in the manual and some solder points are missing/not the same.  The partially stuffed board is here: 

http://picasaweb.google.com/103078014592468973736/Bottlehead#5537786106126040610

In short, p.13 talks about soldering a wire from points bA to bB with an "S" shaped wire.  My board has no such points, though it has all other solder points in different orientations from the manual.  I can't make sense of the solder points that DO exist to match them to the board as represented in the manual.  Can anyone help me figure out what points are the bA and bB on my board?

Thanks.

Edit:  Hnmm.  I can't seem to get the pics to post, so I've tried just posting the link.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 10, 2010, 08:25:39 AM
Thanks, guys.  In looking it over, I just assumed though different, the two boards could both be wired to work.  The only issues I figured I'd have are the "s-shaped" wire connector between bA and bB and the connections to the quickie circuit.  If there is a way to do this without the Queen having to send a replacement board, I'm happy to take instructions for how to wire this board properly.  If all traces are visible on the board I have, I may be able to figure it out from the manual photos and schematic.  If I can't work it out, I'll call her.

Oh, note too that the transistors I got don't have the metal ground plate on the back for orientation.  I assumed the side opposite the one with writing was the same as the metal plate (per most transistors I've used).  If anyone thinks I've got it wrong, please let me know.

Carl
Yes, the board you have should work just fine. I'll dig up the board designs and try to describe how to hook it up, but it may take a few hours.

There's a sticky on the General Discussion board which describes the MJE350 changes.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 10, 2010, 08:50:02 AM
OK, it didn't take that long after all.

The BIG DIFFERENCE is that the large MJE350 transistor is reversed between the boards. Coupled with the different transistors, this can be confusing - be careful there!!! If you look carefully, you will see that the three terminals of the transistor are labeled E, C, and B on the board, and they are reversed between the boards. Tiny print, hard to see!

Here's a map, going clockwise from the O terminal (which is the C4S output, in case you wondered) around the "A" end:


old board     new board
O               OA
I                IA
-                (-reg)
K                Kreg
-                -reg
+                breg connected to rreg
G                bA

Of course for the PJCCS you only use the I, O, and G connections; the rest are for the shunt regulator function which is not used
.
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: 2wo on November 10, 2010, 10:51:56 AM
Scroll up this page, there is a photo of the correct PCB...John
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: cpaul on November 10, 2010, 04:09:01 PM
Paul,

Thanks a ton for looking into this.  So as I understand it, I'd solder a jumper wire between the two G points to replace the "s" wire, check and perhaps flip the transistors depending on how i soldered them (looks like I DO need to resolder them), and use the O, I and G points per the manual for connections to the quickie?  There are 2 solder points immediately to ether side of the 120k resistor at the ground side, one of which has a G next to it.  They appear to be so close as to be electrically connected.  Can I assume both are tied to the resistor so one can be used for the jumper wire and one for the connector to quickie?  Similarly the silkscreen O seems to span between two points suggesting either one could be used.  One is clearly connected to the collector pin of the transistor.  Can either be used for connection to quickie?

Carl
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Paul Joppa on November 10, 2010, 05:36:45 PM
You got it, dude!

Look at both sides of the PC board to see the connections, but usually I have put multiple solder points that are connected together near each other. (The "-" points on the older board are an exception, but you can see that they are connected even though the "K" point is between them. I fixed that on the newer board.)
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Doc B. on November 11, 2010, 05:24:55 AM
Oops, sorry guys. I have a faint recollection of "helping" in the packing room a while, back by packing PJCCS kits. Coulda been my bad. I'll ask Eileen to check the kits in stock to make sure we don't send out any more with the wrong board
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Wanderer on November 12, 2010, 04:35:59 PM
Got my PJCCS finished and installed.

Just to recap - I am running the the Quickie as a headphone amp with Specos to power AKG 240M 600 ohm phones using the "5 watt/1k" taps.  I had been using plate chokes now replaced with the PJCCS.

I had enjoyed the QUICKIE rigged out as above but found "Stereo Spectacular" recordings sounded "okay" but lacking the spectacular. Telarc CD "The Stokowski Sound" was fine but not awesome.

With the PJCCS installed the spectacular is back. Through the AKGs the Quickie sounds warmer in the lower mids and upper bass. The dynamics that seemed compressed before are much more in evidence.

Less whiz bang CDs like MOZART Violin Concertos ARCHIV 477 7371 or Hesperus "Early American Roots" MMCD216 sound better as well. I am much more aware of center fill imaging and hear less emphasis of hard left and right information (headphones remember).

I have more listening to do and if you have a Quickie, even with the plate chokes, you should try the PJCCS mod.  

          

Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: porcupunctis on July 27, 2011, 06:36:22 PM
Len, I would like to know more about the low-pass quickie you made.  I was considering the same thing myself.

Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Grainger49 on July 29, 2011, 09:14:28 AM
Randall,

Len contacted me and since you didn't leave any contact information I'm posting the schematic he sent me.

Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: porcupunctis on July 29, 2011, 05:44:40 PM
Sorry about that, still catching on.
Was that the Schematic for the low-pass filter? 

My email is:
[email protected]
Title: Re: First official Bottlehead Quickie upgrade - the PJCCS
Post by: Grainger49 on July 30, 2011, 01:03:56 AM
Looking at the schematic I think it is so that the Quickie can be used for headphones, using the transformer, or for normal operation as a preamp.

This modification cuts the output by a factor of four.