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Reply with quote  #1 
Hi Guys,

I have been doing a bit of reading, and very close pulling the trigger, just have a few questions to ensure my plan and understanding is spot on.

I am looking to buy the SOB 15W OTL and 300B Masterpiece Preamp.

The other pieces I plan to interface it with are:
Rega Planar 2 Turntable
Project Phono Preamp
Aaron ATS-5 Loudspeakers (93dB/w/m sensitivity, 6 ohm impedance).

1. Will there be any issues with Australian power @ 240V 50Hz?
2. Will 15W be sufficient for these speakers? How much will the 6ohm load affect it?
3. How difficult are these kits to assemble? I studied electrical engineering and did a fair bit of PCB and Surface Mount work, but that was close to a decade ago and havent done a great deal since. I am patient and methodical.
4. Is there anything im missing from this plan? My Phono stage into the 300B Masterpiece to feed the 2.2V SOB Input should all work nicely?
5. Any Aussies on here with recommendations for tube vendors?
6. What are the must have tools or tips you wished someone had told you before you did your first build?

I am really excited by the challenge of this project, as the feedback from this community is amazingly positive.

Any help or advice would be great.
Reply with quote  #2 
1. TS supplies kits at Oz voltages.
2. I am unfamiliar with those speakers.  But you chose the right amp for those speakers.  OTL amps like impedence.  IMO, at 93dB you should be okay with what you have, but it won't play at deafening levels.  This is the one item you're probably going to want to upgrade/swap-out at some point in the future, to something with at least 95 dB sensitivity, and at 8 ohms, but again that is just a suggestion and it isn't immediate. 
3. With your former experience, assembling these should go smoothly.
4. No problems with that set up that I can see.  Project phono pre's are quite good and I used one into TS equipment prior to building the TS phono pre.
5. I know other Aussies that purchase their tubes from USA or Canadian vendors.  
6. A good hot soldering iron/pencil; 40 watts minimum.  A multimeter.  A magnifying glass.  Miniature or small needle nose pliers and wire/side cutters.  A good pair of wire strippers.  And although I tend to read instructions when all else fails, I have found it particularly helpful with TS kits to read the entire instructions cover to cover before beginning any assembly.  One other thing I have learned, having assembled numerous different TS kits, is to check the parts inventory to make sure everything is there, and that things such as transformers, voltage regulators, capacitors all match the values they're supposed to have.

Good luck.  I think I speak for many here when I say once completed the only thing you'll ask yourself is why you waited so long to do it.
Reply with quote  #3 
Amazing response, thanks mate!

I got these speakers cheap for second-hand (previous ones were poor 87dB), expecting they would be decent with this amp - once it is all built and working acceptably I'll see if I need more.
Reply with quote  #4 
Can I please just confirm this tube selection is correct for this amp and preamp?

JJ 12AU7 and JJ 300B for Masterpiece
JJ EL509-S and JJ ECC81 for SOB


Reply with quote  #5 
Yes, those are the correct tube types.
If you read through some of the Masterpiece threads, the general opinion is that the 300B brand/type doesn't make a significant difference, so you could save yourself a few dollars there. PSVane HiFi series @USD120-140/pair, Shuguang 300B-98 a little more these days. Satisfied user of both.

Antique Electronic Supply (AES) or Amplified Parts (same company, different website) often have discounted sales on their tubes, so if you're not in rush, another chance to save. They stock all the JJ types. Good service to our part of the world at sensible shipping prices
Reply with quote  #6 
Any advice on which to build first? Which is simpler/shorter? What sequence would you use and why?
Reply with quote  #7 
I agree with CHARLIEM.

If you are satisfied with reasonable in-room sound pressure levels, 15w should drive the AARON speakers okay.

If you are looking to party and rock the house though - or if you are a fan of DUB-STEP, ELECTRONICA (or any other music with HUGE synthesized bass notes) you may well fry a tweeter with the clipping distortion that will develop when the amp is pushed beyond its capabilities.

If you are looking for an affordable audiophile speaker - that offers a good deal more in-room efficiency - try a pair of these.
(KLIPSCH RP-160M...)
RP-160M-Angle-Cherry Both.jpg 


In any event, both TRANSCENDENT amps that you have selected will be keepers over the long term - as you improve ancillaries.
(Especially the speakers...)

Enjoy the journey!

-SONDEK (Over the ditch in Kiwiland...)

Reply with quote  #8 
Yeah I will upgrade after I experience them and make a call.

Are the horns in Klipsch ok? Not fatuiging?
Reply with quote  #9 
Good question.

Have no fear.  The KLIPSCH RP-160M has a top end that I can - and do - easily live with, listening to music all day long, as I work from home.  Even though I generally listen with tubes, this ease of treble remains true, even when I trot out my solid state amp.

(The venerable NAD 3020i with horizontal input shelf at rear is a stunning combo with the RP-160M...)

I understand from comments made in numerous hifi forums that KLIPSCH speakers have something of a reputation for being a bit harsh and revealing in the tops.

I can't comment on too many KLIPSCH models, but the two that I have spent time with are: -

KLIPSCH HERESY III (Not for me...)
KLIPSCH RP-160M (Yup... I bought them!)

To my ears, the older HERESY III definitely had a slightly more aggressive lower treble - but I felt that they were very much less extended at the very tops than the RP-160M.

By contrast, the new RP-160M has a solid rubber-lined horn mouth, so this probably explains how KLIPSCH have managed to tame the aggressive lower treble.  Best of all, the RP-160M is VERY extended in both top and bottom frequency extremes.  Once they are fully run-in, the bass depth, speed and quality is simply astounding.

Frankly, the side by side battle was easily won by the RP-160M.  No real contest, but a real surprise given the huge price differential which sees the HERESY III more than 3 times the price of the RP-160M, here in New Zealand.

Incidentally, despite the differing efficiency specs of these two KLIPSCH models, I found these speakers to be absolutely identical regarding efficiency.

To understand this better, I actually ran the two speakers side by side - one HERESY III on the left channel with one RP-160M on the right channel.  I tried a couple of different low-powered amps in this mode - 1.5w SE-OTL being one -  and the image was perfectly centred - but with the RP-160M always providing greater air and spacial clues.

(Incidentally, neither speaker is quite efficient enough for the SE-OTL, but pleasant background volumes could be achieved without a problem...)

The KLIPSCH speakers can get them up to very loud in-room levels on a little as 5-10w.  On both speakers, 15-20w will give you rock the neighbourhood volumes.

Don't overlook the (not so little) KLIPSCH RP-160M.  It will give you everything you want and more with a quality 10w+ amp.

(On the SOB, it will be absolutely bitchin'!!!)
Reply with quote  #10 
Wow thanks for the great response.

I was naturally looking more toward floorstanding models- any experience with those? RP250?

Those rp160 sound like a great option! I will check them out.
Reply with quote  #11 



I'm happy to share what my ears have learned over the years.


I find the term 'floor-standing speaker' unhelpful.  Why?  Because it is a bit ambiguous.  Does it refer to the size of the speaker?  Does it mean that the speaker reaches down to the floor and requires no 'stand' at all?  In either case, I find that there are other factors that make a bigger impact on the sound.


The other factors are the actual design of the speaker.


The type of speakers that have never worked for me, are 'Transmission Line' designs.

(Google this term and read-up for more detail...)

Plenty of audiophiles LOVE transmission line speakers designs, but they are not for me, I just find the bass a bit slow and ‘after the fact’.  Transmission Line lovers will tell me that I have never heard a decent one… And they’d be right.  But I have tried.


So, to my ears, I find non-transmission line designs the best.


Well implemented 1-way, 2-way and 3-way speakers can all sound great.  I find designs with more drivers – particularly if there are two drivers in parallel – are not for me either.  They just don’t sound right to me.  The same is true for ‘passive radiators’ and the like.

(Google these terms for more detail…)


I’m not sure if this discounts the floor-standing models that you had in mind.


This stuff is highly subjective, of course.  And different ears will have different opinions and experiences, but sharing opinions and experiences are all we can offer here and that’s what these forums are all about.


My suggestion?  Stick with a highly efficient 2-way or 3-way dynamic speaker design - make sure the tweeters are at ear-height and avoid corners and back walls - and avoid transmission line designs.


I hope this helps.

(Contentious stuff above, so fully expecting a tirade of conflicting views...)



Gary Kemp
Reply with quote  #12 
"Stick with a highly efficient 2-way or 3-way dynamic speaker design"

--------- why not 1-way? 
Reply with quote  #13 

"Why not recommend a 1-way?"

I own several professionally designed 1-way speakers.  I love them for what they do so very well.

But I feel I cannot recommend them unconditionally to an audio newbie, because each design features a material compromise.  That is one of the following: -
  • Very restricted low frequencies
  • Rolled-off tops
  • Fairly restricted sound pressure levels achievable; or
  • Unaffordable for an audio newbie

(I accept that a handful of very expensive 1-way designs may have solved all of these problems...)

Certainly, if someone can live happily with any one of those limitations, 1-way cannot be beat.

I hope this makes sense.


PS:  I deem the addition of subwoofers and/or super-tweeters to be a move away from the true 1-way topology (and magic!)...

Reply with quote  #14 
One way aka full range.

I have had several one way designs. Different Fostex, Lowther and Seas Exotic.

the latter is a speaker which answered all my musical desires of a full range.

Yes no super deep lows, I have the GRF Tannoy for that one but from a musicallity and super low level detail the Seas is beating them all.

Yes I like Lowther too. Build once the TP1 lots of work but even hard rock sounded great.

The Fostex for the price are a steal. Put them in Madisound cabinets and also build once the dino horn lautsprecher a little big but wow what a sound.

As we speak building a new enclosure for the seas exotic. Using now 12" schedule 80 drain pipe. When round no reflections. The top bottom reflection can be easily canceled out.

I know about nirvana but never heard them. people I know really love them.

80% of the music is in the mid register. The seas will not satisfy if super low bass is important to you. So Reggae is not the best music to play through them.
Reply with quote  #15 

Thanks for contributing.  As a Lowther owner myself (PM5As in Medallion II BLH), your mention of the TP1 caught my attention.  Did you build the pair to which you were referring?

Additionally, I've looked at the Seas driver you mentioned with interest many times.  Can you briefly offer some thoughts on its performance?  

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