Hi, I just joined the Bottlehead family!

[mediumjim]

Hi all:

I just bought my first Bottlehead, that being a Foreplay II that has been modified for 6fq7/6cg7 tubes.  I can't wait to get it and audition it with my Marantz 9 VAC's.  My present preamp is a serviced and aligned McIntosh MX-110 that is a good one.  It is an early one with the thumb wheel balance control.  

It will be real interesting to see which one gives the biggest sound-stage and transparency.  If the Bottlehead is close, I plan on doing some upgrades to it that should put it over the top.  

The lesser of the two will inherit a Parasound HCF 1200A Amp for general everyday use; TV, FM Stereo and some back-round CD's.  

With that said, what are the best bang for the buck upgrades I can do to the Foreplay II?  My only concern is that I understand that the FP II's have a slight hum issue.  If this is the case, is there a cure?  I also understand much of it in the FP II's is how well it was built/soldered.  The guy I'm getting mine from sounded like he's a solderhead and knows what he's doing and put about 150 hours of playing time on it.  He built a FP III which he did the same mod to 6fq7/6cg7 tubes, so apparently he liked the tone of these tubes.  Ironically, the driver tubes in my Marantz's are 6cg7's! 

Thanks,
Jim

[Grainger49]

Jim,

Welcome to the community!

The FP 2 can be surprising.  I've never seen one modified for the 6FQ7 before but the crew at Bottlehead uses them for voltage regulators.  They know the tube quite well.  BTW, one of the best sounding widest, deepest soundstage preamps I have ever heard used the 6FQ7 for the linestage.

The McIntosh is pretty stiff competition. 

My FP 2 has never hummed since the day it went into service. Yours probably won't either.  If it does in your system a shot of the belly might help with wire routing if you do have hum.  Amplifier gain and speaker sensitivity also affect where you operate relative to the noise floor of any preamp.  The most often cure was to convert the heaters to DC if it was heater caused hum, easy to check.  Ground loop hum is "a whole 'nother animal." 

Again, welcome!

[mediumjim]

Hi Grainger:

Thanks for the comments, I have no doubt the FP II I'm getting is a fine sounding unit (that's why I got it!).  Thanks for addressing the hum question.  I'm guessing that there are some who were less meticulous in their building of it that resulted in their's humming.   The person I obtained mine from has also built a FP III with the same tube compliment and loves it. 

Jim

[Grainger49]

Jim,

You should have little or no hum issues caused by the heaters considering the shielded signal wires.  That thing about ground loops is something addressed in the FP III which switches the hot and ground (opening unused input grounds) at the same time.  But most preamps I have seen only switch the hot.  So it is not likely to be a problem for you either.

[Doc B.]

With that said, what are the best bang for the buck upgrades I can do to the Foreplay II?

Because of the power transformer voltage and current limitations the best bang for the buck might be to sell the Foreplay II and buy a Foreplay III. FPIII has much more power supply headroom that allows for DC heaters which will eliminate the hum of the FPII and shunt voltage regulation which will refine the frequency extension and resolution. It isn't really possible to do that with the stock FPII power transformer. You get halfway there and at least go to DC heaters on a FPII by upgrading to a PT-1 power transformer. That would probably be very good bang for the buck. It does require one new mounting hole and the addition of new rectifiers for the B+ and heater supplies.

http://www.bottlehead.com/store.php?crn=221&rn=439&action=show_detail

[mediumjim]

Hi Doc:

I will consider that, but the builder of the FP II that I got did address the power supply and has made the following mods:

Yes it has a few mods built in. It has Pseudo dual mono power stage (PDMPS), each signal wire is shielded and has its own ground, done like they did on the Foreplay III , the volume controls are in shunt mode, it has  RRSF which is a filter to take any nasties out of the electricity coming from the wall. It uses Vishay-Dale resistors, which I think sound very good. And finally it has an IEC connector  so you can try different power cords if you like.
It does not, however, have the attenuators or the constant current mod, but there is room for them if you would want to put them in at a later date.

After I give it some hours of critical listening I will see what the best thing for me is. 

[JC]

Ah, you already have some of the "bang-for-the-buck" mods I was going to suggest.

The Reverse Recovery Spike Filter (RRSF) actually addresses the power supply diodes, I think, more than anything on the AC mains.  On my FP2, it reduced the .5 mV hum to ~ .3 mV, IIRC, by knocking down a nasty little spike on the hum waveform.

.3 mV hum is a very good figure for a pre with ac heating for the tubes; as Doc indicates, about the only way to improve that is to go to DC on the heaters.  In my case, the hum from the speakers was lower than the mechanical hum from the Stereo 70 my FP2 was feeding, so the point was moot.

Another area you might address is the output coupling caps.  I imagine you could easily spend as much on a couple of new caps as you spent on the FP, but you don't need to.  Just remember if you decide to try different ones, they will most likely require some hours of break-in.

[ssssly]

In addition to what you have already stated my FPII has wallwart DC heaters and I replaced the power supply input resistor with an inductor. The constant current sources are also huge improvements as are upgraded signal and power supply caps. Don't know how it compares to a FPIII or your MX-110 but I can tell you it sounds really good. And mine has no noticeable hum.

[mediumjim]

Thanks for all input and great information.  I will have a good base of information in the event I need to do some work on it.  First I will need to sit down with it when it gets to me next week and bond with it.   From what I've read here and other places, I've made a good choice of preamps, as well as being fortunate to have obtained one from someone who knew a little bit about them in the first place.

I can tell that by the quality of the responses that I've also found that Bottleheads are good people! 

[mediumjim]

Hello all:

Tomorrow the brown truck is scheduled to pull up and deliver my Bottlehead.  I've already been thinking about building a new case for it and possibly doing some cosmetic work to the top.  But first, I really am anxious to give it a good session with the Marantz 9's with an AH! Tjoeb 99 Tube CDP. My main speakers are early 90's KEF 104.2's that are in perfect order and are mated with Bower and Wilkens Subs. 

Turns out my Bottlehead does have upgraded Iron (from the pictures of it).  I haven't seen the underside yet, but I would imagine from my correspondence with the guy who made it, it will be meticulous. 

I really want to thank Doc and his team of experts for making available affordable audiophile gear. While this will be my first Bottlehead, I've heard wonderful things about Bottlehead and wish I was more knowledgeable in the area of electronics as I would love to try my hand at making some of the kits. 

Instead of prattling on I will wait to report back after trying out my new (to me) Bottlehead Foreplay II with upgrades. 

Jim

[mediumjim]

I thought that "General Discussion" Section was a place to:
"Feel free to talk about anything and everything in this board."

Well I was wrong I guess! 

Sorry if a breached any rules or ruffled feathers by talking about my incoming FP2 that is highly modified and with tubes that probably will make have a deeper and wider soundstage than the FP3.  I guess at the end of the day it is all about selling the new products that cost more and earnest and frank discussions about discontinued products are treated with disdain. 

I should have realized that after Doc's post that was pushing his new product.  It is too bad as Doc does have nice products for the audiophile on a budget. 

Yes, maybe I should have posted in the legacy section initially, under the heading General Discussion allowed me to believe that I was allowed to  "Feel free to talk about anything and everything in this board."

Jim

[Doc B.]

The mods are trying to put interesting posts the in place they will be most likely to be found in the future by other folks who can benefit from the info. There are a lot of earlier Bottlehead kits out there and a lot of folks who will appreciate the info you have shared. IMO moving a post from General to a specific forum is an "upgrade". It means we consider the post worthy of archiving, not treatment with disdain.

[Grainger49]

There were several threads that got moved to Legacy Products today.  Your is one of two on the Foreplay 2 threads and one on the Parasex.  Any of the Paramours, Paramour IIs, Parabee... there are a lot of retired products out there that when put where it can be found will help everyone.  There is also a Bottlehead speaker that is retired.

Take a look at the threads in this folder and you will see a lot of FP 2 threads.  There are three threads started by me on Legacy Products so there is still a lot of support for all Bottlehead products.

[mediumjim]

Okay, if you say it is an upgrade.  Doc I still struggle with your original post where you dismissed the FP2 and indicated that the best bang for the buck was to pass it off to someone else and then get a FP3.  Yes, it was prior to me informing you as to what was already done to it.   It appears that all of the proper modifications have been perfomed on it and beyond as it has 6FQ7's that are said to produce an unbelievable soundstage.  I would love to see a Bottlehead published mod for 6FQ7's if and after the folks at Bottlehead build a couple test models with them.

Happy Holidays,

Jim

[Doc B.]

As for dismissing the FPI and FPII, I should be the last person to do that. It was our bread and butter for many years, we manufactured and sold many thousands of them. It was a kit that was in the right place at the right time.

Part of the redesign that changed FPII to FPIII was to implement a bigger power transformer that allowed for a more sophisticated power supply and part of the redesign was to revise the chassis to one that would allow the installation of more tube types. These kinds of changes were things that were suggested by our FPII customers. We have built several Foreplay IIIs with 6SN7s, which is of course the octal equivalent of the 6FQ7. And we have published the necessary changes, which are simply to change the sockets to octal and to adjust the value of the resistor on the heater supply. The mod would be simpler if using 6FQ7s as one would only need to rewire the heater connections of the existing sockets and do the resistor change.

http://www.bottlehead.com/smf/index.php/topic,567.0.html

I happened to find that I prefer the sound of the 12AU7 to the 6SN7 in this circuit when we tried it. Others may prefer the 6SN7 or 6FQ7. I posted my suggestion that the best bang for the buck may be to sell a Foreplay II and buy a Foreplay III because of the more sophisticated power supply regulation it has and the improved frequency extension and soundstage that, in my opinion, it can produce. Adding the shunt regulator to the FPII would be a rather involved modification and in the end it might just be easier and more cost effective to move to the FPIII because of that. I don't think it has to be one you buy from me, it could be a used Foreplay III.