Princeton Reverb clone advice

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foreverstrung
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Re: Princeton Reverb clone advice

Post by foreverstrung »

PT hammond 291AEX
OT hammond 1760E

Those are what I use

If you put in a 12” speaker you will have to lower the value of the cathode bypass cap on V1A to 4.7uf. I highly recommend the Celestion cream Alnico. It sounds amazing in a PR. Expensive but worth it imho
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I think the PT is supposed to be a 290AX, not the not the 291AEX, that's for a Champ. IDK if it'll make a big difference, but I think I'm going to pick up a 290AX unless I get a thumbs up on the 291AEX.
The 1760E OT will work instead of the 125A10B called out for in these drawings. Reverb driver too.
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Re: Princeton Reverb clone advice

Post by JMPGuitars »

foreverstrung wrote:
Thu 06/29/23 12:03 pm
I think the PT is supposed to be a 290AX, not the not the 291AEX, that's for a Champ. IDK if it'll make a big difference, but I think I'm going to pick up a 290AX unless I get a thumbs up on the 291AEX.
The 1760E OT will work instead of the 125A10B called out for in these drawings. Reverb driver too.
You need to stop guessing and start reading spec sheets.

https://www.hammfg.com/part/290AX
https://www.hammfg.com/part/291AEX

Tell me, what's the difference between the two of those?

Nobody else answer that please.

Thanks,
Josh
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Re: Princeton Reverb clone advice

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The 291AEX is smaller than the 290AX and it has 4 additional leads that are not needed.
The 290AX is about $101.86 @ Mouser and the 291AEX is $118.08.
After reviewing all the details, the 291AEX will work, but it's a little more expensive, a little smaller and has 4 additional leads that are not needed with this layout I'm using.
My concern was using this layout from the guy in the UK's PCB board, that the PT and OT might be a problem if I didn't use exactly what he was throwing down (or the equivalent of). Especially after I see he's modified the original 60's PR layout. Needed some clarifying as I've been harvesting the components.
Thx for the help. Researching the details helped a lot.
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Re: Princeton Reverb clone advice

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foreverstrung wrote:
Thu 06/29/23 3:09 pm
Researching the details helped a lot.
That's the key. The only functional difference, as you saw, was those extra leads for different source voltages. Since you're in the US, you can use either one.
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Re: Princeton Reverb clone advice

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I always use the 291aex. It’s great and the lower B+ is more vintage sounding
The last thing it lacks is juice
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Re: Princeton Reverb clone advice

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Bieworm wrote:
Thu 06/29/23 4:00 pm
I always use the 291aex. It’s great and the lower B+ is more vintage sounding
The last thing it lacks is juice
Of course you do, you can't use the 290AX. 😉
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Re: Princeton Reverb clone advice

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JMPGuitars wrote:
Thu 06/29/23 5:57 pm
Bieworm wrote:
Thu 06/29/23 4:00 pm
I always use the 291aex. It’s great and the lower B+ is more vintage sounding
The last thing it lacks is juice
Of course you do, you can't use the 290AX. 😉
Lol🤣
I should have looked at the datasheet, d’oh!!!
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Re: Princeton Reverb clone advice

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Bieworm wrote:
Thu 06/29/23 9:37 pm
Lol🤣
I should have looked at the datasheet, d’oh!!!
Thanks for helping me drive home that point. 😉😉🤣🤣🤣
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Re: Princeton Reverb clone advice

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JMPGuitars wrote:
Thu 06/29/23 10:18 pm
Bieworm wrote:
Thu 06/29/23 9:37 pm
Lol🤣
I should have looked at the datasheet, d’oh!!!
Thanks for helping me drive home that point. 😉😉🤣🤣🤣
You must have a jar filled with points by now. I don’t have a jar like that… there’s no point🤣🤣🤣
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Re: Princeton Reverb clone advice

Post by foreverstrung »

Can I see some pics of a completed Princeton Reverb. I can see plenty online, but I'd like to see some from you guys on here
Thx
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Re: Princeton Reverb clone advice

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IMG_7492.jpeg
IMG_7486.jpeg
IMG_7489.jpeg
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Re: Princeton Reverb clone advice

Post by foreverstrung »

It's hard for me to make out exactly where you have your shielded wire placed and my layout that I'm using shows no shielded wire at all. Where exactly do you have these please? Appreciate you clarifying.
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Re: Princeton Reverb clone advice

Post by foreverstrung »

Besides the shielding wire locations Bieworm, did you use a direct ground to chassis @ the input jack? My layout I'm using does not have this and when doing the TMB build, you pointed this out to me on that. Wondering if this would be the same application. Perhaps always that way.
And your bus wire. Is it a 16g? It's real clean. Straight. What I've been using is in a roll and difficult to get it as straight as what you've posted. What are you using?
Thx
Dave
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Re: Princeton Reverb clone advice

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foreverstrung wrote:
Mon 07/10/23 5:38 pm
Besides the shielding wire locations Bieworm, did you use a direct ground to chassis @ the input jack? My layout I'm using does not have this and when doing the TMB build, you pointed this out to me on that. Wondering if this would be the same application. Perhaps always that way.
And your bus wire. Is it a 16g? It's real clean. Straight. What I've been using is in a roll and difficult to get it as straight as what you've posted. What are you using?
Thx
Dave
Always a ground connection near the input. Don’t rely on the input jack to serve as ground.
I use a lit if shielded wire. I know it’s not necessary, but I feel more comfortable with longer wire runs from the pots when they’re shielded. Don’t hurt anyway..
There is a simple trick to straighten the ground buss wire. Clip off a length. Clamp one end in a battery drill machine and clamp the other end with a plier. Spin while holding the plier tight… and..voila!
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Re: Princeton Reverb clone advice

Post by foreverstrung »

So this is it assembled. Still need to run the voltage test. Clean it up a bit. Building the combo cab this wknd per the princeton reverb specs.
princeton reverb 1.jpg
princeton reverb 2.jpg
princeton reverb 3.jpg
princeton reverb 4.jpg
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Re: Princeton Reverb clone advice

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"Yes waiter, I'd like some capacitors with a side of amplifier." 😉
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Re: Princeton Reverb clone advice

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"Yes waiter, I'd like some capacitors with a side of amplifier." 😉
Yes, it does look cap heavy. I considered using smaller coupling caps instead of the orange drops and 20uF's I was unable to find anything smaller. Mouser is out of stock till like november.
What I found "headscratching"about this build is that it's got 2 fuses and a standby switch. I considered eliminating 1 of each, but my experience level is relatively low and I didn't want to start modifying out the gate and making a mess. I thought better to stay on point and modify after, if desired.
what about that switch area? It looks pretty crowded to me. I went through dozens of switches and options be fore I settled with this. Still feeling a bit cautious about it.
LAYOUT_princeton_reverb.pdf
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Re: Princeton Reverb clone advice

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I never do standby switches on amps with a tube rectifier…
The fuses are : one for the mains power and one for the HT. HT fuse is good to have in case of shorting power tubes, but wit a well built and well biased amp you would hardly need it IMHO
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Re: Princeton Reverb clone advice

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I never do standby switches on amps with a tube rectifier…
The fuses are : one for the mains power and one for the HT. HT fuse is good to have in case of shorting power tubes, but wit a well built and well biased amp you would hardly need it IMHO
That makes sense. It's there now though so I'll stick with it.
Before I can power this up, (i've done the highlight run thru), I need a 1/2a fuse. I've got 1a and 2a 30mm fuses that will work, but I'm not going to rush it tho I'm excited to see how it powers up and voltages.
I did find some 20uF 500v E caps from mojotone that are about 25% smaller. I've ordered them and will swap them out with these monster JJ's. I'm surprised tho as I searched and shopped extensively. I did pick up some others, but they were even larger and none were cheap.
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Re: Princeton Reverb clone advice

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foreverstrung wrote:
Sun 07/30/23 12:40 pm
I never do standby switches on amps with a tube rectifier…
The fuses are : one for the mains power and one for the HT. HT fuse is good to have in case of shorting power tubes, but wit a well built and well biased amp you would hardly need it IMHO
That makes sense. It's there now though so I'll stick with it.
Before I can power this up, (i've done the highlight run thru), I need a 1/2a fuse. I've got 1a and 2a 30mm fuses that will work, but I'm not going to rush it tho I'm excited to see how it powers up and voltages.
I did find some 20uF 500v E caps from mojotone that are about 25% smaller. I've ordered them and will swap them out with these monster JJ's. I'm surprised tho as I searched and shopped extensively. I did pick up some others, but they were even larger and none were cheap.
Don’t swap the caps. Josh was only joking about them. And I think mainly the orange drops. Those are sooooo big. I never use them. People use them in F€nder type amp builds to be “period correct”. But that’s BS! F€nder used blue molded caps in the blackface era. Modern Mallory 150’s are the obvious replacement for those. It’s only the show-off guys using the orange drops, and for no other reason than showing off. If you look at Emprize Amps you’ll see he uses panasonic poly caps. His builds are awesome and they sound immaculate. The only remote remark I have is he solders the components on top of the turrets… but they are really well soldered and built
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