PT for a 5E3 Deluxe

[Yoda]

Hello all,

I’m going to be building a 5E3 tweed Deluxe using a Mojotone small parts kit but I’m choosing my own transformers. I think I’ve narrowed it down to the Hammond 1750E and the Hammond 290BX.

My question though is regarding the 290BBX, as Hammond seems to list this as the more vintage correct transformer but the voltage seems too high at 355v. Otherwise the BX (330v) seems like the better way to go and I’m leaning towards going with it. There are some comments floating around though that the higher current of the BX will reduce the famous sag of the tweed Deluxe, hard to know how true that is without buying both and doing an A/B test. 138mA vs 115mA, not sure how much of a difference it really makes but it’s there. The bias tap of the BX is a plus even though I don’t plan to use it in the beginning but I can take it or leave it so it’s not a deciding factor.

So if anyone has any pros/cons regarding the 290BX vs the 290BBX I’m all ears.

I should also state my goal is to build a mostly faithful replica of the 5E3. So I’m not really looking to play with 6L6s or other mods. The output transformer may change as well if I decide to build a head version because I would want 4/8/16 ohm taps on a head but for the time being the plan is to build a combo like the original.

Thanks in advance.

[sluckey]

My question though is regarding the 290BBX, as Hammond seems to list this as the more vintage correct transformer but the voltage seems too high at 355v. Otherwise the BX (330v) seems like the better way to go and I’m leaning towards going with it. There are some comments floating around though that the higher current of the BX will reduce the famous sag of the tweed Deluxe, hard to know how true that is without buying both and doing an A/B test. 138mA vs 115mA, not sure how much of a difference it really makes but it’s there. The bias tap of the BX is a plus even though I don’t plan to use it in the beginning but I can take it or leave it so it’s not a deciding factor.

So if anyone has any pros/cons regarding the 290BX vs the 290BBX I’m all ears.

I would use the 290BX. Read this from a guy that has built over 90 5E3s this year...

https://el34world.com/Forum/index.php?t ... #msg324104

[Yoda]

Awesome, building 90 5E3s is certainly a lot of experience!

Thanks for the recommendation, pretty much all I needed was to hear that I’m going the right direction with the 290BX. I’ll probably wait another day before ordering in case anyone comes along with compelling reasons to use something other than the 290BX.

[ChopSauce]

Thanks for the link, yet I don't know how to handle the (looping) fact that the poster thanks yourself (Steve) for suggesting the BX as a PT ...

I'm sure the advice is a good one, though, as there is (approx.) a 20% current increase from 115 to 138A, which is twice the minimum required to be called "significant" amongst the scientific (research) community - have I been told -
(+ you may experience voltages pretty higher than expected with modern rectifiers)

I'm glad I can hijack this thread to discuss the OT, yet I may as well start a new one, but as the original poster mentions the choice for the OT, too:

any thoughts about the fact that the TAD OT(*) seems a much better choice?
___

(*) https://www.tubeampdoctor.com/en/detail ... tegory/105

[sluckey]

Thanks for the link, yet I don't know how to handle the (looping) fact that the poster thanks yourself (Steve) for suggesting the BX as a PT ...

Haha! It's quite a puzzle. P2pAmps is a friend of mine. Early this year when he was building his first 5E3 he used the 290BXX because that's what Hammond recommended. He was not happy with the sound and he suspected it was because his B+ was too high. We had some lengthy email exchanges and my recommendation was to try the 290BX. End results... he liked the lower B+ and the sound so he ordered about 100 more 290BXs. So, all I did was make the recommendation. Mike put it to the test and proved it was a good choice. Listen to the sound demo below. Should help make up your mind.

Here's a discussion about p2pamps' 5E3, complete with a sound demo...

https://el34world.com/Forum/index.php?t ... #msg316467

[Yoda]

Awesome, all those assembled 5E3 chassis are a sight to behold!

[Yoda]

Well now that the PT decision is settled (going with the 290BX), let’s get into OTs.

Regarding the 5E3 I read everywhere that 8-8.5k is a must for the correct sound. I was going for the 1750E myself but I’m aware there’s a slightly beefier version rated for 20 watts instead of 15 watts (1750H? Can’t remember off the top of my head).

The TAD OT linked earlier by another member looks good but appears to ship from Europe so not really a good option for me.

If you don’t mind me asking, what OT is P2P Amps using in all those 5E3s?

Also, on the more theoretical side of things I have seen comments that the OTs with multiple impedance taps on the secondary do not sound the same or have the same response as an OT with a single secondary tap. Any truth to this? Because it would be more versatile IMO to have multiple impedances available if given the choice but I don’t want to sacrifice tone either.

Thanks in advance.

[sluckey]

I settled in on Hammond 1750EP for OTs and the 290BX on the PT on all the 5E3s. Normally see about 365vDC on the plate and around 20v on the cathode bias resistor.

https://www.hammfg.com/files/parts/pdf/1750EP.pdf

[ChopSauce]

Thanks again Steve, for that and all the valuable information you (also) spreaded through the internet ...

Any comment about paper wound (output) transformers - for example Hammond 1750E vs 1750EP - anyone?

[Yoda]

Well I’m finally beginning this build. Any opinions on Orange Drops versus something like Sozos or Jupiter capacitors? I’m still going to initially build it with the orange drops that come with the Mojotone small parts kit I have here but I already feel like upgrading to something more “authentic”.

[Colossal]

Well I’m finally beginning this build. Any opinions on Orange Drops versus something like Sozos or Jupiter capacitors? I’m still going to initially build it with the orange drops that come with the Mojotone small parts kit I have here but I already feel like upgrading to something more “authentic”.

Orange Drop is a generalized term to include all orange capacitors that look like a cough drop. However, the dielectric materials can be either polypropylene (SBE 715P and 716P) or polyester (Sprague 225P, 418, SBE 6PS, Mallory 150, etc). To my knowledge the orange drops supplied by Mojo are 715P (polypropylene) and are not "period correct" in materials or form factor for a 5E3 build. The 715s will make a great amp (tubes and lead dress are more critical to the sound, but parts can play a role in the final result) but if you are trying for a more authentic amp, then Sozo or Jupiter caps might be a better choice. I would go for the Jupiters (polyester film foil construction) or SBE 6PS polyester orange drops as a second choice if period correctness is not the first choice, but authentic sound is.

[sluckey]

Reach out to zephyrblau. He might sell you some Astrons.

[Yoda]

Great info, thank you. Yeah I knew there was several types of orange drops and I should have specified but since I had mentioned having a Mojotone kit you nailed it with regard to which ones I have here on hand.

And Sluckey, I’ll look into those. You’re talking about the vintage yellow Astrons? Are they known for consistently being good after so many decades like the blue molded caps of the blackface era?

[sluckey]

And Sluckey, I’ll look into those. You’re talking about the vintage yellow Astrons? Are they known for consistently being good after so many decades like the blue molded caps of the blackface era?

I don't know, but they are very authentic.

[Yoda]

Well I just completed this tweed Deluxe build and while doing my voltage checks I noted that one 6V6 runs 10 more volts on the plates than the other, is that cause for concern? Doesn’t seem like it would be I just thought it was odd since I’ve never encountered that before, usually the power tubes are all at the same voltage on the plates +/- 1v.