PRR-176 REV 4 Build Thread ***Manual up!***1/16/14 - (chk 1st post)

[muffy1975]

Hi everyone.

My 176 is working !!!  Really beautiful sound, nice compresion.  I use two Lundahl transformers in each channel.
I used 470R pads, opamp input option, opamp output option.  I use two power transformer for 220Vac.  I made both transformers jumpers as shown in Abe's PDF and prh told us. By now, I only calibrate 0dB for meter.  I haven't tried link options yet.

At the beginning, tried with ICs in everywhere and checked everything worked.  Later, I changed to gar2520 discrete opamp in the first and the last, as Abe told us, leaving 22p caps.  The unit sounds even better.  Important: I found clearly that there is less distorsion with discrete opamps, much better option.

Thanks to everybody, it is really useful everyone's experience to reach my unit finished.

Hey,

can you post a picture of how you wired up the two power tx to get the 100V line?

Are you Europe based? I am in England and need to know how the power is hooked up properly?

Also, when you say opamp in and out do you mean you used IC opamps or discrete ones? did you try the OPA2604 for input first or Ne5532? Before you switched to discrete opamps?

many thanks in advance


Michael

 

[muffy1975]

Also,

i am failing to understand the mix up with the valve PCB.

If i connect 1 to 9 what's wrong with that?

i plan on using a separate  valve connector/base anyway perhaps

Can you tell em which pin on the valve base goes to which hole on the PCB.

ie: - PCB 1 goes to Valves Base 1?
PCB 2 goes to Valve base 2?


Thanks


Michael

 

[anvl]

Hi, Michael. I'm from Spain and now on holidays for a few days in Dublin.

I use two different power transformers for 220v.
- 220v prim to 18v+18v sec
- 220v prim to 110v sec
Both primarys are connected on IEC plug and both secundarys are connected directly to PSU board... that's all.

Regarding opamps, at the beginnig I used NE5532 and NE5534 ICs to check everything worked. Later I changed to gar2520 discrete opamps in two of the three sockets, as Abe suggested to do, leaving IC in the center socket.

For valves connections only match the pin 1 of main PCB with pin 1 of the tube.

I'll post some pictures in a few days.

Salud.

 

[muffy1975]

hey,

thanks for getting back.

Do you have an order code for the 220v to 110v transformer? i did not know that this exists?
you're not talking about a step down transformer are you? if so that is a novel approach. Must be dangerous? Is there any galvanic isolation?

regards


Michael

 

[anvl]

http://ie.mouser.com/Search/m_ProductDetail.aspx?R=DST5-120B39virtualkey67300000virtualkey673-DST5-120B39

 

[anvl]

In Europe based powering 220Vac, you can also use Gyraff mode for this PSU.  The first tx should be 220V prim to 18+18V sec (transformer number 1) and the second should be 120V prim to 18V sec (transformer number 2), but used in reverse mode, which means that you should connect the 18V of tx number 2 as a prim to one of the two 18V of tx number 1.

What do you think?

Anyway I used the other option that I explained above.

Regards.

 

[e.oelberg]

my 139 and 140's dont fit in through the holes. which ones have yall ordered?
I ordered fairchild 139 and 140 in mouser.

yes they fit, you maybe have to make them a bit mor pointy with a plyer, but it is tight

 

[berkleystudios]

my 139 and 140's dont fit in through the holes. which ones have yall ordered?
I ordered fairchild 139 and 140 in mouser.

yes they fit, you maybe have to make them a bit mor pointy with a plyer, but it is tight

I have ordered  several and still have not gotten them to fit and way i try. im about to file them haha

 

[e.oelberg]

my 139 and 140's dont fit in through the holes. which ones have yall ordered?
I ordered fairchild 139 and 140 in mouser.

yes they fit, you maybe have to make them a bit mor pointy with a plyer, but it is tight

I have ordered  several and still have not gotten them to fit and way i try. im about to file them haha

I made them pointy with a plyer

 

[DIY-solder]

A few things which are not clear to me...

Are all pots LIN or LOG?

Is this correct info for toroid:

Primary:
2 x 115v (230v)

Secondarys:
120v 50mA
18 v 1.2A
18v 0.4A

What Telefunken tubes will do the job?

Thanks!

 

[boneindian]

Hey I just wanted to confirm that for North American builders (those of the 120V wall power) the below transformer works with the power supply when wired according to the wiring guide.  My earlier problem was of course caused by a classic yet embarrassing user error of not being able to discern the fuse slot from the extra fuse holder in my IEC.  Sometimes you have to leave it on the bench for a week until the idiocy subsides. 

http://www.mouser.com/Search/ProductDetail.aspx?R=VPT36-1390virtualkey55310000virtualkey553-VPT36-1390 

Just wanted to confirm this since I don't think there's been posts from any American builders besides Abe with completed units.  All voltages look happy.  All I'm waiting on now is those replacement tube PCBs!

 

[taliska]

Hey all, going to build this soon...just collecting parts at the moment.

Just wondering about a couple of things:

Do I have to pm or email Abe to get the replacement tube pcbs or is he sending them out to everyone? Anyone got the email address?

Is there enough room in dan's case for European builders? I'd like to do it in 1U, but reading through the thread it seems that UK/EU builders might need two transformers? Might be a bit of a squeeze?

Cheers,

Kaz

 

[boneindian]

You might want to drop him a line if you want the replacement pcbs.  I still haven't gotten mine.  I decided to go with a 3U case though to I'm inserting my tube holders into the back side of the original boards and letting them stand up straight. Incidentally I'm hoping Abe or someone else will tell me if that wouldn't work...

 

[abechap024]

Hey all, going to build this soon...just collecting parts at the moment.

Just wondering about a couple of things:

Do I have to pm or email Abe to get the replacement tube pcbs or is he sending them out to everyone? Anyone got the email address?

Is there enough room in dan's case for European builders? I'd like to do it in 1U, but reading through the thread it seems that UK/EU builders might need two transformers? Might be a bit of a squeeze?

Cheers,

Kaz

Hi Guys,
Got the tube mounts and sent out the first round of them. Sent them to everyone that already emailed me, but if you still need send me an email at [email protected] with "Prr tube mounts" or something in the title and your address. Im using an automated mailing program so I should be able to ship things much more frequently (thank goodness).

Also with european builders, You can use the dual primary trick, just change R10, R11, R12 to 3K9 @ 5watt resistors and change the 100V zener to a 5W one (just to be safe, might be unnecessary) like a 1N5378.

You will be inputting 240V which after the rectification (times by 1.414) will get  340V and the plates of the tubes take about 10ma each so using three 3K9 resistors should knock down the voltage into the 110V range. Someone let me know if my thinking is off but should make it much easier for european folks!

 

[berkleystudios]

email sent about tube mounts. build is close to being done . need a handful of components and a case, finding it had to get a custom order done....

 

[taliska]

Hi Guys,
Got the tube mounts and sent out the first round of them. Sent them to everyone that already emailed me, but if you still need send me an email at [email protected] with "Prr tube mounts" or something in the title and your address. Im using an automated mailing program so I should be able to ship things much more frequently (thank goodness).

Also with european builders, You can use the dual primary trick, just change R10, R11, R12 to 3K9 @ 5watt resistors and change the 100V zener to a 5W one (just to be safe, might be unnecessary) like a 1N5378.

You will be inputting 240V which after the rectification (times by 1.414) will get  340V and the plates of the tubes take about 10ma each so using three 3K9 resistors should knock down the voltage into the 110V range. Someone let me know if my thinking is off but should make it much easier for european folks!

Thanks for the info Abe. Mail sent.

I didn't know what the dual primary trick was, but I did a bit of googling and found out about it. One of the things I read about it is that it isn't necessarily the safest thing to do? The link I found was at:

http://www.diystompboxes.com/smfforum/index.php?topic=33904.10;wap2

The bit regarding safety says:

You're taking a safety chance using two parallel primaries from a toroid transformer with one as a primary and the other as an output. That's because as pure noted, the primaries are only isolated from each other by only the insulation of the magnet wire, which is good only for maybe 300-400V. Primary to secondary isolation in all consumer products is at least 1500V and often 4000Vac. A power line transient could easily puncture the magnet wire film and give you a primary-secondary short and shock hazards.

I recommend that you use either two toroidal transformers back to back or one flatpack semi-toroidal. The flatpack has the two "primaries" wound in separate sections of the two bobbins and so they're isolated by the bobbins, not only the magnet  wire film.

I think given that at this point I value (safety and) 1U over cost, I think I'm going to go with the Don Audio transformer as it seems to be the right solution for me. I'm assuming that others are using it in 1U successfully?

Looking forward to building this! ;-)

 

[ding]

Abe,

When should we expect the updated build guide? Been holding out on my build waiting for it. No biggie though as I was busy with a ez1073 but tha project is coming to a close and I am so looking forward to this project.

Thanks

 

[tazwolf]

Taliska, The Don Audio transformer is too tall to fit in a 1U case.
/Taz

 

[taliska]

Taliska, The Don Audio transformer is too tall to fit in a 1U case.
/Taz

Thanks for the info Taz! ;-)

I guess that means that 1U might be impossible in the EU then?

The back to back transformer solution (as seen in the G9) would utilise two transformers and while each one might be shorter, I was under the impression that the best way to arrange that type of solution is to stack them? (which obviously would mean that they would end up taller than the Don Audio solution anyway!).

I suppose the less optimal solution of placing them side by side would be possible, but I don't know what the side effects would be...

Of course, that's assuming there's room in the case for them side by side as the circuit board is pretty big!

Which approach have other EU builders taken? (sticking to 2U minimum I guess?)

Cheers,

Kaz

 

[anvl]

Hi.  For European builders I think there are three options for powering:

A) Using two different power transformers for 220v.
- 230v prim to 18v+18v sec
- 230v prim to 120v sec
Both primarys are connected on IEC plug and both secundarys are connected directly to PSU board... that's all.

B) Using Gyraff mode (back to back).  The first tx should be 230V prim to 18+18V sec (transformer number 1) and the second should be 120V prim to 18V sec (transformer number 2), but used in reverse mode, which means that you should connect the 18V of tx number 2 as a prim to one of the two 18V of tx number 1.

C) Using Abe's suggestion.  Dual primary trick, changing R10, R11, R12 to 3K9 @ 5watt resistors and change the 100V zener to a 5W one (just to be safe, might be unnecessary).

I used option A) and it's working in a 2U case.

Regards