Tubelab Simple SE - Transformer Assistance

[ChrisR1983]

Hi All,

My first post!

Just finishing building some rather nice speakers using scan-speak drivers. They're amazing... I'm now about to build a shiny new Simple SE valve amp for them.

Completely new to this kind of thing so looking for some advice.

I'm in the UK and my speakers are 8Ohm. Can someone advise the part number for both a 240v transformer and the OPT from Edcor please?

I'm going to build a chassis from Welborne Labs; can anyone suggest alternative chassis? Cost is not an issue and neither is location, as long as they ship to the UK.

Thanks

Chris

 

[boywonder]

Chris: The search button is your friend, there are zillions of posts here concerning transformers for the Simple SE.

If you don't mind a hammond, a 374BX would probably do the trick, it's universal voltage input and 375-0-375 @ 175ma output. Others here can address whether Edcor makes a 240V power transformer.

What sensitivity are your scanspeaks? Keep in mind that the simple SE is a fairly low power amp (around 6-8 watts or so), and is happiest with speakers that are fairly sensitive, depending on your listening habits.

Tubelab George has lots of tube and transformer info on his web page here:

http://www.tubelab.com/AssemblyManualSimpleSE/TubesAndTransformers_SSE.htm

 

[boywonder]

Can someone advise the part number for both a 240v transformer and the OPT from Edcor please?



Chris

You want a 5K/8 ohm SE transformer. For the CXSE Edcors, the P/N is CXSE25-8-5K

(25 watt, 8 ohm secondary, 5K primary)

Alternatively, you could go with an Edcor CXSE25-8-3.2K (3.2K primary impedance) for a little more power out and a little more distortion.

Study the tables on the bottom of the page on Tubelab George's link posted above, and note the relationship between B+, power out, distortion, load Z (this is your OT primary impedance) and Rk (cathode R).

The above info assumes that you want to run EL34's/KT88's/6L6GC's.....

 

[ChrisR1983]

Thanks for the reply; I was in a rush writing the post as I was about to go into a meeting at work and realized that it was quite rude of me to demand this information. I'll have a thorough search and check back if I get stuck.

Regarding the sensitivity of the speakers it hovers around the 86-91dB mark. How will this effect things?

Thanks

Chris

 

[CharleyW]

You may want to re-think ordering from Welborne Labs.

 

[pointy]

http://www.sowter.co.uk

if the money is no object................and they are very good to talk to

 

[boywonder]

Regarding the sensitivity of the speakers it hovers around the 86-91dB mark. How will this effect things?

Thanks

Chris

86-91 db is a huge range.......Most Scan-Speaks that I am aware of are around 87-88 db or so, although I'm not expert on these. Going from 88 db sensitivity to 91 db sensitivity doubles the volume for the same watts input to the speaker, so if you are hoping to crank Motley Crue with a SimpleSE and 87 db sensitivity you may be disappointed.

To generalize, if your speakers were 98 db sens, a SimpleSE would be more than enough power to blast your head off under reasonable home listening conditions, although many people are happy with 5-8 SE watts into 90-93 db speakers. These folks are typically not cranking up heavy metal, etc.

Going from 88db to 94 db sensitivity quadruples the volume for a given power. (SPL doubles every 3 db)

You may want to search the forum for Wellbourne labs posts before ordering.....

 

[wa4swj]

If I may, I'd like to agree with the comments about Welborne Labs.

Regarding the output transformers, I just built a Simple SE using Transcendar Transformers and they are quite good. I'm very pleased with the sound.

Regards,

 

[boywonder]

Chris: Here is a link related to the SimpleSE and speaker sensitivity:


http://www.diyaudio.com/forums/showthread.php?s=&threadid=107665&highlight=

 

[ChrisR1983]

Thanks guys - some really useful information. I searched regarding Welbourne Labs. I wont be ordering my chassis from those guys then!!

Does anyone else know of a supplier that sells wooden enclosures that will ship to the UK?

Thanks

Chris

 

[rknize]

The XPWR059 would be a suitable power transformer, if you wanted to go with Edcor. It has a 120/240 primary and its ratings are:

375-0-375 @ 175mA
6.3V @ 6A
5V @ 3A

It's a bit overkill on the heaters, but not by much. You could run a 5U4 rectifier if you wanted. The B+ voltage is on the high side and the current is a little less than mine. Would be good for EL34s and 6L6 types. Just make sure you spring for 500V capacitors.

The one I have on mine is the XPWR035:

370-0-370 @ 200mA
6.3 VCT @ 5A
5V @ 2A

If you really wanted the extra capacity for B+, you could just custom-order what you need. Just give them the model number as a starting point and then give the deltas.

I've been remodeling in the basement and so the SSE is seeing a lot of use. It's a great amp and I have to keep it turned way down so that the rest of the house isn't going thump-thump all night.

Russ

 

[JeroenR]

Thanks guys - some really useful information. I searched regarding Welbourne Labs. I wont be ordering my chassis from those guys then!!

Does anyone else know of a supplier that sells wooden enclosures that will ship to the UK?

Thanks

Chris

Try http://www.ae-europe.nl/aanbieding_behuizingen.htm ...

They also make transformers. I ordered my TubelabSE transformer from them...

Jeroen

 

[ChrisR1983]

Thanks Russ.

All helpful stuff! There's a lot of reading to be done and I'll get my head around it eventually.

Edcor seem to be a popular choice on here so I'll definately go with something by them.

Still having issues with the chassis though...

Thanks

Chris

 

[dubdub]

Thanks Russ.

All helpful stuff! There's a lot of reading to be done and I'll get my head around it eventually.

Edcor seem to be a popular choice on here so I'll definately go with something by them.

Still having issues with the chassis though...

Thanks

Chris

Hi Chris

for the chassis for my simple SE project I used Pesante 300m from HiFi 2000, better quality than Hammond alu/or steel and has a very nice face plate too.

http://www.modu.it/pesante.html

But if it is a wooden chassis your after then try VT4C located in Hong Kong? While I never bought from him because I considered his postage costs to be too high for my needs- it may be worth it if you buy other items too like transformers (or even a choke)


http://www.vt4c.com/shop/program/main.php?cat_id=1031&group_id=2&hit_cat=

I have not heard anything bad about him (Chung?) and he responds to quote requests promptly.

Good Luck...and oh don't scratch that chassis!!

 

[Tubeornot2b]

xformers...

From what I see at their site Electra Print ships internationally.... you may want to check out using theirs.... http://www.electra-print.com/contact.php#ordering. Limiting to a single output impedance option betters performance and lowers price, worth looking into, That is what I have in my 45 amp. They sound amazing. Make sure to specify correct I limit for the trannies.

you may want to talk to this guy for chasis.... http://cgi.ebay.com/ws/eBayISAPI.dl...ageName=ADME:X:RTQ:US:1123#ht_1347wt_1167....

I must note that though I have dealt with and will again with Electra Print I have not with the chasis fella. But I am considering it.

As far as speaker sensitivity. earlier this year I setup a system with my Audio Electronics SE1 with 2a3 tubes in the (fairly large) living room , driving Sonus Faber 87dB speakers. It gets plenty of loud before hitting the distortion compression zone.

 

[diecast]

I can endorse EletraPrint - Jack Elliano is a good guy. Shipping to UK may be cheaper than you think - two custom OPTs for my SSE fitted in a single Flat Rate Box for US39 a little while ago. Takes PayPal.

For the chassis, once I worked out the layout, I got a 4mm anodised aluminium plate machined by:
http://www.schaeffer-ag.de/
They provide the layout software. Pricing is not too expensive and the finish is excellent. I mounted it on a wooden base (four sides to make a sort of open ended frame) and added an aluminium angle under the transformers to prevent sag.

 

[waam68]

Philip at Bluebell has reasonably priced Hammond chassis...the steel are pre painted in grey or black & work well.

http://www.bluebellaudio.com/

Mike

 

[diecast]

Seconded. Bluebell is mostly aimed at guitar amp stuff but is an excellent source of all things Hammond, including the 374BX (where I got mine) and some v nice hardware, switches etc (ditto).