Tube rolling on Foreplay III

[debk]

Anton

I replaced the stock EH 12au7's with NOS RCA clear top 12au7's.  It made a noticeable improvement in the sound quality.

Debra

[Anton]

Thanks everybody for recommendations.
I just finished extended upgrade for my Foreplay III.
I am currently using JAN  Sylvania 6189 for output tubes, which were a replacement for stock 12AU7s. To be honest I didn't hear a lot of difference sound wise.
I decided to follow Paully's advise and ordered a matched pair of Mullard CV4003 from Upscale Audio. Not cheap actually ))) so I hope I am gonna like it.
Although to be honest - it sounds very good the way it is right now)))

[Paully]

Make sure you post back what you think (even if you don't like them, won't hurt my feelings!).  I will be curious to know.  And you can get some more recommendations if you need them.  I think you will be quite happy once they break in.  20 hours should be plenty.

[howardnair]

i just did some work on my foreplay III- put obbligato 4.7's premiums and put some mazda cifte 12au7

it sounds quite  nice -especially since i am driving a a SS mcintosh mc250--i have ordered some obbligato PIO caps to give them a try as grainger highly recommends them

[Anton]

here is the update...
I am using Mullard CV 4003 for almost 3 weeks now. Think it was long enough for tubes to break-in.
I like the sound, but honestly speaking I don't hear much difference from stock 12AU7 and JAN Sylvania 6189 I was using before. I came to conclusion that my ears are not that sensitive to capture all these nuances. I guess it is just the way I am, and I accepted the fact that I am not one of those guys who can write page-long vacuum tube review )))
but that doesn't prevent me from enjoying my favorite music on a gear I assembled with my own hands - and that's all what matters )))

[Paully]

Nothing wrong with liking cheaper tubes!  They're cheaper!

[Deafer_than_a_doornail]

Hi All!

Can I use a pair of Philips E80CC's in my Foreplay?

Here's the datasheet:

http://www.hifitubes.nl/weblog/index.php/philips-e80cc-datasheet/

I see both "12.6" and "6.3" volts for heater voltages, and I'm not sure which applies.

[Paul Joppa]

Hi All!

Can I use a pair of Philips E80CC's in my Foreplay?

Possibly. Look at the curves, for 75v on the plate and 3.6mA current. If the bias is close to 1.57 volts, then it should bias up properly. This appears to be the case. Note that the gain will be higher - 27/17 or about 4dB.

[Grainger49]

This link is not in the FP III folder but anything that could work with the 1 and 2 will work in the III, plus more.  Every number listed will be a drop in replacement unless it says different.

http://www.bottlehead.com/smf/index.php/topic,1027.0.html

[Deafer_than_a_doornail]

Thanks Paul, Granger!

The E80CC is not on the "drop-in" list - would it require some circuit modification for the FP III?

How about for the Extended upgrade?

I also wonder- for the Extended upgrade, should I be looking at matched sets of 3 tubes, or is it ok if the middle regulator tube is not matched with the other two?

[debk]

Been using Psvane 12au7.  I think it is a noticeable improvement over the RCA clear tops i was using before.


Deb

[Grainger49]

Deafer_than_a_doornail,

No, I'm pretty sure that is an oversight on my part.  The E80CC should be on my master list and didn't get transferred to the post.  I will add it.

Edit: The heater current is twice what a FP 1 or 2 can deliver.  It is just fine for the FP III.  So it doesn't belong on the FP 1 & 2 list but would be on a FP III list.

Thanks!  

Extending makes no difference in the tubes.  It does set the current.  Unless you get more creative with tubes, changing the operating point and tube you don't need to adjust the current from the C⁴S boards.

I don't match preamp tubes.  Some do, I don't.  The VR tube needs not be matched to anything.  As long as that one is working you are good.

[Paul Joppa]

I would stay with a 12AU7 or equivalent for the center (shunt regulator) tube on the Foreplay III. You do not want the cathode voltage to drop below 2.5v, because then the 431 chip would not regulate.

[Oberst Oswald]

We don't offer a partial kit, but you can leave out the hybrid shunt reg and keep the 0D3 if you want. It's not as good, but others have done this. They ARE pretty!

I just received the extended kit and want to keep the OD3 tube for the time being and put in the 12AU7 later..  I'm not very good at understanding the electrical prints so what I'm asking is there anything I should be concerned about by leaving it in?  I'm already stumped on the taking all the stuff out in the beginning of the kit right away... is there a simple diagram somewhere on how to do this.  Or should I just install the 12AU7 because its such an improvement I'd be an idiot not to do it?

[Grainger49]

The community suggests you build stock, not extended, first.  Then after becoming used to the stock sound you add the Extended kit and know what changes it brings.