Author Topic: New PR AA1164 build... (Read 16598 times)

SleepLess · « **on:** October 26, 2011, 07:51:36 am »

Hi!

As this one will be staying with me and I have almost unlimited budget to build it I only want the very best. What would you guys suggest as far as transformers go? Have you got a brand in mind? If you also have other recommendations to make concerning other parts (resistors, caps, whatever...) please don't refrain! Just bear in mind that I'm in the EU so the PT has to have a 220, 230 or 240V tap.

Thanks!

Fresh_Start · « **Reply #1 on:** October 26, 2011, 08:48:16 am »

Speaker: Weber 10F150-T (assuming you can get Weber speakers)

There's a long thread in the Archives which may be useful. A search here will turn up lots. A bunch of us built Princeton Reverbs in the 2006-2008 period.

I built two Princeton Reverbs, one with Mercury Magnetics iron and the other using Hoffman's. So similar any perceived differences in sound are just that. However, Hoffman's iron was much less expensive. Don't know if his PT has 220 VAC tap though.

Are you locked into using the vintage Fender layout? If not, F&T filter caps are an excellent choice for the power rail IMHO. Mallory 150 or Xicon coupling caps.

Frankly, spending extra Euros on "high end" components doesn't do much IMHO except for speaker, cab, and output transformer.

Hope that helps,

Chip

SleepLess · « **Reply #2 on:** October 26, 2011, 08:56:05 am »

Quote from: Fresh_Start on October 26, 2011, 08:48:16 am

Speaker: Weber 10F150-T (assuming you can get Weber speakers)

Yes I can, but I'll put the PR in a headshell and use it with a cab loaded with an EVM12L, that's settled...

Quote from: Fresh_Start on October 26, 2011, 08:48:16 am

There's a long thread in the Archives which may be useful. A search here will turn up lots. A bunch of us built Princeton Reverbs in the 2006-2008 period.

I built two Princeton Reverbs, one with Mercury Magnetics iron and the other using Hoffman's. So similar any perceived differences in sound are just that. However, Hoffman's iron was much less expensive. Don't know if his PT has 220 VAC tap though.

Well his store says that he only carries 110V versions so I have to be looking somewhere else. It would have ben my choice though to choose Hoffman's stuff... Oh well...

Quote from: Fresh_Start on October 26, 2011, 08:48:16 am

Are you locked into using the vintage Fender layout? If not, F&T filter caps are an excellent choice for the power rail IMHO. Mallory 150 or Xicon coupling caps.

Absolutely not, see I'm already changing it a whole lot with a headshell and a 12" speaker... I have already tried SoZo blue caps previously and they sounded great, but since I never heard the Mallory 150 I can't really tell the difference. One sure thing is that the Blues look better... lol

Quote from: Fresh_Start on October 26, 2011, 08:48:16 am

Frankly, spending extra Euros on "high end" components doesn't do much IMHO except for speaker, cab, and output transformer.

Mmm... OK. The speaker and cab are decided upon already, so I just need the trannies now...

Quote from: Fresh_Start on October 26, 2011, 08:48:16 am

Hope that helps,

Chip

It does help, thanks a lot Chip!

SleepLess · « **Reply #3 on:** October 26, 2011, 10:10:51 am »

Have you guys ever tried the ClassicTone transformers? I tried one in a 5E3 and it was great. Any feedback on their PR versions?
Thanks!

jojokeo · « **Reply #4 on:** October 26, 2011, 11:16:05 am »

yes, and they're fine. For components you could buy higher-end pots but you won't hear the difference, you will feel the difference when turning them and they may last longer in the end. Use a Hoffman board, not the original style paper-type boards that come ready made and that can be conductive. Another important thing that money can buy "better" are the tubes you put in. Almost as important as the speaker for hearing characteristic differences.
Things to concentrate on that money can't buy but are also very important are proper layout, lead dress, and grounding. These can render the other stuff pointless if not done correctly because what difference do they make if the amp oscillates, has parasitic oscillations, 60hz humm, etc...or worse - an electrocution waiting to happen.

bruno · « **Reply #5 on:** October 26, 2011, 12:29:00 pm »

Which country are you in, if you don't mind me asking?

SleepLess · « **Reply #6 on:** October 26, 2011, 12:34:48 pm »

Quote from: bruno on October 26, 2011, 12:29:00 pm

Which country are you in, if you don't mind me asking?

No problem... I'm in France.

billcreller · « **Reply #7 on:** October 26, 2011, 12:50:48 pm »

The bunch PRs that were built a few years back were using the mods and schematic etc from Hotblueplates, and the layout for a turret board was done by bnwitt (Barry Witt), if I remember correctly. I built one from that, and it came out great, even though I'm not a Fender fan, and I still have it. Only thing I did different was to use a 12 inch Weber speaker.
The thread for it should on here someplace yet ....

SleepLess · « **Reply #8 on:** October 27, 2011, 08:22:41 am »

So I think I'll go with Classictone trannies. They're a lot cheaper than the hype MM and seem to be at least as good. I'll let you know how it sounds when it's done.
Thanks for your input!

Fresh_Start · « **Reply #9 on:** October 27, 2011, 08:35:49 am »

+1 on spending money on tubes. Much more bang for your buck than hi fi caps, etc.

IMHO every individual amp will "like" certain tubes in specific positions. I've got a collection of new 12AX7s from Tung Sol, Shuguang, EH, Sovtek, Mesa, etc. plus a few NOS and ANOS to play around with. I have learned NOT to make assumptions about which tube will sound best before experimenting.

SleepLess · « **Reply #10 on:** October 27, 2011, 08:44:15 am »

Got the tube ground covered pretty well already...

tubeswell · « **Reply #11 on:** October 27, 2011, 06:37:01 pm »

Don't skimp on a good PT, especially if you're in a 'euro-voltage' country.You want enough iron in the core to handle the inductance at 50Hz well. Not enough iron = short-lived PT. Some transformer makers of 'euro-voltage' PTs don't seem to understand this (still!) and produce cheaper small PTs that don' have the staying power. Beware of this.

See attached graph. Think of the area under the function line as the amount of inductance happening in each case. the blue line (230V 50Hz) has more area under the function line than the red line (110V 60Hz)

SleepLess · « **Reply #12 on:** October 28, 2011, 03:33:25 am »

Wow, this is getting real technical here... Thanks a lot but could you just say what specs the PT should be within then? What specs should I be particularly beware of? Thanks!

The ClassicTone PT has a Plate winding 550 or 630V CT @ 100mA and Heavier current capacity (100mA vs. 70mA). Would that be good considering your graph?

MM may be great as well but the total reaches $235 compared to $90 from ClassicTone... These prices exclude the Reverb transformer.

tubeswell · « **Reply #13 on:** October 28, 2011, 05:16:04 am »

The PT secondaries will need to be spec'd to handle the overall tube load. What I was talking about was the amount of iron in the core (for iron-core PTs). Ideally your euro-voltage PT should be about 10-20% bigger than an equivalent (i.e.: for the same secondary specs) US-mains-voltage PT . This will help it to keep cool while running, and therefore last longer. This is likely to have a cost implication (which is why I suggested 'don't skimp')

carausius · « **Reply #14 on:** October 28, 2011, 08:22:44 pm »

Hammonds are good transformers for EU based builders, Classictone I've used as well. Also there's another Portugal based option for PR & most other Fender type PT's http://www.rhodeselectrics.com/TransformersPower.html

I'm still waiting for a reply for Fender style PT's from an English transformer company, they have already made Super Reverb PT's but I'm more interested in 125P1B / 125P26A types. Postage from overseas adds a lot to the total cost of builds

bluesbear · « **Reply #15 on:** October 29, 2011, 11:03:37 am »

I love Weber Signature speakers. I have a Sig 10 ceramic in one Deluxe clone with a small cabinet and a Sig 12 alnico in another with a larger cab. Both sound great once broken in. An added advantage is that they are so cheap, though that's not why I use 'em.
$30 for ceramic 10"
$45 for alnico 12"!!!!!!!!!!
Their power rating (25 watts) is just right for a PR.
Dave

tubeswell · « **Reply #16 on:** October 29, 2011, 04:33:45 pm »

Quote from: bluesbear on October 29, 2011, 11:03:37 am

I love Weber Signature speakers. ...
$45 for alnico 12"!!!!!!!!!!
Their power rating (25 watts) is just right for a PR.

+1 I've got a Sig12 in my PR cloney thing and its awesome

SleepLess · « **Reply #17 on:** July 31, 2012, 07:49:05 am »

Hi.
I'm finally getting to this build and I've just received the parts. I bought MM trannies all over and the PT's reference is FBFPP/240. It has a Heater CT which is pretty uncommon (at least for me, it's the first Fender build tranny I have that has a HT CT).
So the question is easy: am I using it or am I leaving it and installing the 100 ohm resistors on the indicator lamp and the usual Fender stuff? And of course if I do use it, how, where, and what does it change?
Thanks a lot!

John · « **Reply #18 on:** July 31, 2012, 01:39:44 pm »

It's probably easier to use the CT. I think Sluckey said he always uses the CT if available with no problem. Little less soldering, 2 less resistors. HTH!

SleepLess · « **Reply #19 on:** July 31, 2012, 02:03:15 pm »

Quote from: John on July 31, 2012, 01:39:44 pm

It's probably easier to use the CT. I think Sluckey said he always uses the CT if available with no problem. Little less soldering, 2 less resistors. HTH!

Yes I'd rather use it but the problem is how... Do I just connect it to ground and don't install the 2 100ohms resistors on the lamp or is there something else?

John · « **Reply #20 on:** July 31, 2012, 02:13:14 pm »

Oh, sorry! Yes that's exactly it. Bolt it down with one of the PT mounting nuts. Don't install the 100 ohm resistors, you only use either the CT or the 100 ohm resistors to make the artificial CT. Hope I've explained clearly this time!

SleepLess · « **Reply #21 on:** July 31, 2012, 02:27:17 pm »

Got it! I just need to not install the 100ohms resistors and ground that HT CT to the spot where the resistors would have been grounded...

Thanks!

Willabe · « **Reply #22 on:** July 31, 2012, 05:55:45 pm »

The heater CT can be grounded at the same place/with the B+ CT is grounded.

Look in here for grounding info;

http://www.freewebs.com/valvewizard2/Grounding.html

Brad

SleepLess · « **Reply #23 on:** August 03, 2012, 11:27:32 am »

Great!
Before switching it ON (the build is finished) I would need you to confirm the CE cap wiring (40+20+20+20uF). What puzzles me is that it hasn't got a ground lug unlike the JJ cap of same values... So does this mean that it's not grounded at all or is there a log that is both a filter and a negative lug? If it's the case it's the lug that has no marking (the three others have a D, a square and a triangle).
Here's a pic of what I've done... Thanks!!!

SleepLess · « **Reply #24 on:** August 03, 2012, 11:43:50 am »

Finally found a picture of an original PR:

The four outer twist lock lugs are bent over backwards and soldered directly to the chassis. I suppose I could do the same? Or is there a modern better way?
Thanks!

Willabe · « **Reply #25 on:** August 03, 2012, 11:51:44 am »

Quote from: SleepLess on August 03, 2012, 11:43:50 am

The four outer twist lock lugs are bent over backwards and soldered directly to the chassis.

They did that to hold the cap can in place and to ground it at the same time. The can itself has the negative ends of all the caps, 4 in this cap can, connected to it internally.

You have a clamp holding the cap can in place to the chassis, so you don't need to solder the 4 outside lugs to the chassis. Just solder a wire to any 1 outside lug and run that to your main chassis ground. Use a nice heavy piece of wire, maybe a cut-off piece of wire from the PT. That's what I'd try first.

Make sure you know which of the inner 4 lugs is the 40uF cap. That is the 1'st B+ filter cap.

Brad

SleepLess · « **Reply #26 on:** August 03, 2012, 01:16:33 pm »

Thanks! I soldered a wire from one of the outer lugs to the chassis ground and the amp works perfectly! It's real silent even on 8!
This amp is beautiful!!!
Thanks!!!

Willabe · « **Reply #27 on:** August 03, 2012, 01:22:55 pm »

Great!

Now do we get to see some nice gut shot pics?

Brad

SleepLess · « **Reply #28 on:** August 03, 2012, 01:38:33 pm »

Sure... Gut shots served:

Willabe · « **Reply #29 on:** August 03, 2012, 03:22:24 pm »

WOW! Very nice indeed!

How about a pic of the back/top side of the trannys so we can see the iron?

Brad

SleepLess · « **Reply #30 on:** August 03, 2012, 03:34:58 pm »

Thanks. I didn't take any shots of the top... But I have Mercury Magnetics all over. I wish I could try Hoffman's trannies but I need 230V here and his are 110V period... And the less I multiply sources the less costly the amp is... I try to stick with 3 online sources max and it's already quite hard to stick to that...

Willabe · « **Reply #31 on:** August 03, 2012, 03:35:19 pm »

One more thing, you do have a light bulb limiter to use on 1'st start ups and testing old amps/power supplies for safety?

Here's a link, with thanks to Sluckey, to how to build one if you don't. They work great are inexpensive to build and have saved a lot of guys a lot of heart brake and $$.

http://home.comcast.net/~seluckey/amps/misc/Amp_Scrapbook.pdf

Brad

SleepLess · « **Reply #32 on:** August 03, 2012, 03:50:06 pm »

Quote from: Willabe on August 03, 2012, 03:35:19 pm

One more thing, you do have a light bulb limiter to use on 1'st start ups and testing old amps/power supplies for safety?

Here's a link, with thanks to Sluckey, to how to build one if you don't. They work great are inexpensive to build and have saved a lot of guys a lot of heart break and $$.

http://home.comcast.net/~seluckey/amps/misc/Amp_Scrapbook.pdf

Brad

That's some really interesting read! I'll have to delve into this! Thanks a lot!

HotBluePlates · « **Reply #33 on:** August 04, 2012, 01:46:31 am »

Excellent looking build! You did a really good job, easily as good as the original blackface Princeton Reverbs (I've owned a few of them).

SleepLess · « **Reply #34 on:** August 04, 2012, 04:38:40 am »

Quote from: HotBluePlates on August 04, 2012, 01:46:31 am

Excellent looking build! You did a really good job, easily as good as the original blackface Princeton Reverbs (I've owned a few of them).

Thanks a lot!!!
The only thing that actually tickles me when I build Fenders (whether Tweeds or Blackfaces) is the grounding scheme choice. For Marshalls I use the Larry Star Grounding (learnt on the MetroAmp board) which is just perfect 100% of the time.
As for Fenders I'm still trying things: buss soldered across the pots, floating buss wire (like I did on this PR build), brass grouding plate, terminal strips. All my Fenders have different grounding schemes and I don't feel that they're perfect as such. There is always a moment when I ask myself "should I solder this ground wire here or there?" "Should the buss wire be grounded close to the input jacks or closer to the PT", "should the terminal strip be grounded here or there and which wires get connected to it or not"?
Grounding Fenders is the only field where I'm not 100% content of what I do...

bnwitt · « **Reply #35 on:** August 04, 2012, 09:14:03 am »

Very nice build Sleepless.

SleepLess · « **Reply #36 on:** August 08, 2012, 08:27:39 am »

Quote from: bnwitt on August 04, 2012, 09:14:03 am

Very nice build Sleepless.

Thank you bnwitt!
I'm currently off to another build, a 5F6A. I changed the caps value on the PR from 25uF/25V to 25uF/50V and changed the bias cap from 50uF/100V to 100uF/100V and removed the resistor. This little amp sounds great!

I'm also currently thinking about whether attaching the two 100 ohms resistors to the lamp or to the power tubes (between lugs 2 and 8 on one and between lugs 7 and 8 on the other...). I do that on a 5E3 but I don't know if it is recommended on a 5F6A...

Fresh_Start · « **Reply #37 on:** August 08, 2012, 09:35:34 am »

Quote from: SleepLess on August 08, 2012, 08:27:39 am

Quote from: bnwitt on August 04, 2012, 09:14:03 am
Very nice build Sleepless.

Thank you bnwitt!
I'm currently off to another build, a 5F6A. I changed the caps value on the PR from 25uF/25V to 25uF/50V and changed the bias cap from 50uF/100V to 100uF/100V and removed the resistor. This little amp sounds great!

I'm also currently thinking about whether attaching the two 100 ohms resistors to the lamp or to the power tubes (between lugs 2 and 8 on one and between lugs 7 and 8 on the other...). I do that on a 5E3 but I don't know if it is recommended on a 5F6A...

Your PR build looks very nice!

If you are talking about the virtual center tap for the heater winding, there is nothing wrong with tying it to a power tube cathode but you're simply connecting it to ground in a fixed bias amp. The cathode on a 5E3 sits at roughly 22 VDC, not "0" VDC like a fixed bias amp. Using an elevated DC voltage for the virtual center tap ground can help with noise rejection. Not as important in a push-pull amp as a single-ended amp.

Hope that helps,

Chip

SleepLess · « **Reply #38 on:** August 08, 2012, 09:41:05 am »

OK.
Thanks for the kind words!

I have soldered the two 100ohms resistors to the power tubes (pins 8 and 2 on V5 and pins 7 and 8 on V4) instead of soldering them to the indicator lamp.

Ed_Chambley · « **Reply #39 on:** August 08, 2012, 12:33:27 pm »

Very nice indeed. Looks like it would have came from one of fender's best builders.

SleepLess · « **Reply #40 on:** August 08, 2012, 01:13:16 pm »

Quote from: Ed_Chambley on August 08, 2012, 12:33:27 pm

Very nice indeed. Looks like it would have came from one of fender's best builders.

Thanks a lot!!!
Well, there's a bummer though: it looks good but the tremolo is not working!!!! How's about a Fender best builder???

So I need you guys to make this amp sound as righteous as it looks. Here's what I've done so far:
1. Replace V4 with two differnt tubes: to no avail.
2. Put both intensity and speed on 10: to no avail.
3. Check wires going to V4: all good.
4. Measures:
B+ is at 439V (pins 3 of the output tubes) with 230V wiring for 228V wall voltage.
Bias is at 16mA for both tubes (perfectly matched)
V4 pin 1: 255V
V4 pin 2: 0V
V4 pin 3: 2V
Intensity pot middle lug: -44V
5. Changed the 1M resistor to a 220K (one of Sluckey's tricks to increase the tremolo effect), this one, to no avail:

The thing is that the first three V4 pins should be oscillating and they are not...
I don't know what to do.
Thanks!!!

sluckey · « **Reply #41 on:** August 08, 2012, 01:32:32 pm »

Quote

The thing is that the first three V4 pins should be oscillating and they are not...

Are you sure? Those voltages indicate that it is probably oscillating. Use your footswitch to turn the trem off. Does the voltage on V4-1 increase quite a bit?

Quote

Intensity pot middle lug: -44V

Sounds way high for a PR. Adjust the bias to set that voltage to about -35vdc and see if the trem works.

SleepLess · « **Reply #42 on:** August 08, 2012, 02:04:11 pm »

Thank you Sluckey!
OK. I adjusted the bias and I now have -36.4V at the middle lug of the intensity pot. B+ is down to 413V. I can't go lower than that on the bias (I have a 27K resistor on the bias pot). Still not even the faintest sign of tremolo...

Thanks!

SleepLess · « **Reply #43 on:** August 08, 2012, 04:03:45 pm »

Mmm... I have measured my bias which I had to raise in order to lower the intensity pot middle lug voltage. So what I currently have is:
414V B+
-36V at middle lug of intensity pot
25.7mA bias on the 6V6s

I remember that I once had a PR that needed a lower bias on the tubes (17mA) in order to have its tremolo work. The thing is that if I want 17mA on the tubes then I'm gonna have -44V on the intensity pot again, lowering one increases the other...

So what do I need to change/alter in order to have both 17mA bias on the tubes AND -35V on the intensity pot? I'm lost there... Maybe it would work then as my wiring looks all good...

Thanks!

HotBluePlates · « **Reply #44 on:** August 08, 2012, 04:16:42 pm »

Quote from: SleepLess on August 08, 2012, 01:13:16 pm

Well, there's a bummer though: it looks good but the tremolo is not working!!!! How's about a Fender best builder???

I think you're missing a resistor.

Look at the schematic fragment you posted when talking about reducing a 1M resistor to 220k. If you follow the caps from the plate to the grid of the oscillator, there is a 1M resistor which reuns from the junction of two of the caps to the cathode of the oscillator.

In the pictures you posted earlier, there should be a 1M resistor running from your ceramic disc caps, where the blue underboard wire attaches, over to the yellow wire going to pin 3 of the oscillator tube. I don't see that resistor in your pictures.

Add it, and the reverb should come on.

sluckey · « **Reply #45 on:** August 08, 2012, 04:33:31 pm »

Quote

I think you're missing a resistor.

Damn! You're getting good at finding that missing resistor!

SleepLess · « **Reply #46 on:** August 08, 2012, 04:54:09 pm »

Hot damn! I was so concerned about my wiring that I forgot to look at my components!
So the tremolo is working now!!!

One thing though, I don't know if that's normal: the speed increases fine but from 8 to 10 it's like the tremolo totally disappears, is it because it is going so fast that the human ear can't discern the oscillation? Or do I have to alter something until I hear the trem at work even on speed 10?

Thanks, I love this board!!!!

HotBluePlates · « **Reply #47 on:** August 08, 2012, 06:31:59 pm »

Quote from: sluckey on August 08, 2012, 04:33:31 pm

Quote
I think you're missing a resistor.
Damn! You're getting good at finding that missing resistor!

I've been taking notes on how you find amp problems with a good picture.

Sleepless kind of distracted us with a second picture that wasn't from this same amp, which did have the missing 1M.

Quote from: SleepLess on August 08, 2012, 04:54:09 pm

One thing though, I don't know if that's normal: the speed increases fine but from 8 to 10 it's like the tremolo totally disappears, is it because it is going so fast that the human ear can't discern the oscillation?

You can best answer this. If the trem pulses seem to get so fast they blur together, it should be pretty obvious to you, especially if you back the speed down slightly and can hear individual pulses.

You can slow the trem down by making one or more of the three disc caps a larger value.

sluckey · « **Reply #48 on:** August 08, 2012, 06:54:25 pm »

But what are the chances of two people building two different amps with two very different layouts (although exact same trem osc circuit) omitting that very same resistor within 3 weeks right here on Hoffman's forum? And in each case you spotted the missing component immediately! That's gotta be worth a lot of 'ataboys'. You got my attention!

HotBluePlates · « **Reply #49 on:** August 08, 2012, 08:51:55 pm »

Thanks!

But it's the same silly mistake I would make! Maybe that's why I find them...

I've said for a while now the only thing that separates an expert builder from a novice is that the expert knows that when the amp doesn't work, there's a build mistake. So they don't do perfect builds, they find and fix the error faster.

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Author Topic: New PR AA1164 build... (Read 16598 times)