TubeLab SimpleSe and speaker efficiency

[cbutterworth]

I have been given permission to spend a little money on a tube amp for my office at work.

Now, I do not have much to spend at all. It seems that the Tube Lab SimpleSe could be very inexpensive and can output around 10WPC.

Of course, I do not have speakers for my office and was thinking cheap and bookshelf.

Anyway, we recently put some Sony 2-way bookshelf speakers in the baby's room. He likes them and they are around $50 a pair.

Now with a 10W SimpleSE powered by iTunes via the audio jack, going into 87dB speakers, will I hear anything?

Otherwise, can anyone recommend sub $100 higher efficiency speakers.

Charlie

[dsavitsk]

87 is fine for sensitivity, especially for an office, but check the impedance curve.

[planet10]

Originally posted by cbutterworth
can anyone recommend sub $100 higher efficiency speakers.

Are you going to build them?

dave

[arnoldc]

Dave, I'm interested too if what you have in mind is something I can build.

[chrish]

Without the "bells and whistles", this amp would be cheap to build. I guess the big dollars would be saved by using budget output transformers and tubes. The extra filter cap and choke will only cost about $30 extra to include.

I have built this amp and absolutely love it. The design of the board and the detailed instructions on the TubeLab web site allowed me to build a very quiet (as in no hum) sweet sounding amp without really knowing much of the "tricks of the trade" in tube amp construction. I am running the budget Edcor XSE15-8-5K transformers and have found them quite good (I have active crossover and stereo bass units for <80Hz). I am running JJ ECC81 input tube and JJ E34L output tubes. I have also got some JJ KT88 tubes. After several weeks of listening, I have found that I prefer the E34Ls to the KT88s. In my setup the E34Ls sound a little more detailed. The KT88s sound louder in the bass, but in my setup and in my opinion, the bass sounds a little muddier and the highs slightly less detailed. The E34Ls also cost significantly less and offer slightly more output power in this setup.

I might add that I think that this amp would be wasted on an MP3 system, but I am biased, I love mine in my main system.

Another thing that may be worth investigating, audio pre-amps and CD players etc should not have any DC offset in their output but I am not quite so sure about MP3 players and computer soundcards. It might be worth asking some of the more knowledgeable members of this forum if they would recommend adding a capacitor to the input of the amp to protect from DC. I am currently building a little 6BM8/ECL82 push pull amp for my girlfriend ( http://www.bonavolta.ch/hobby/en/audio/ecl82_2.htm ) for exactly the same purpose you are building yours and have decided to add a capacitor to the input just in case her iPod or computer has some DC (this was on the recommendation of my father, an electronics engineer).

If you do decide to build this amp please leave some feedback for the forum and for TubeLab. I think George has sold a few of the boards but have not seen much feedback on the forum or on his site.

Cheers,

Chris

[Sherman]

Originally posted by cbutterworth
...

Now with a 10W SimpleSE powered by iTunes via the audio jack, going into 87dB speakers, will I hear anything?

Otherwise, can anyone recommend sub $100 higher efficiency speakers.

Charlie

Charlie,

In my family room system I have SE KT88 amps putting out about 7 watts. I am using Dynaco A25s in that setup and it goes plenty loud for me in that room. (Room is about 13 feet by 17 feet with an 8 foot ceiling and an 8 foot opening into the next room.) I don't know the efficiency of the Dynacos but I would guess no more than 89dB.

I've also used those same amps with Advent /1 speakers which are slightly less efficient and probably about the same as yours. I found that for almost all the music I listen to they were also quite loud enough.

In an office 10WPC would be plenty I think.

[cbutterworth]

Great replies - Thanks!

I have just invested a chunk of change on a Cornet2 phono-pre from Jim Hagerman. I used premium parts for signal caps, etc., so the cost was quite substantial ($400 - $500), but it's worth it. I expect that my Aikido pre cost a similar amount, although I am less sure, it may have cost quite a bit less.

Having had six months of vacuum tubes in my system, I have decided that I love them. My main amp is a 55W solid state AKSA 55N. This is supposed to be a very high quality amp and has a solid DIY following. This, coupled with lack of space means that a vacuum-tubed main amp for my home system is out of the question. Hence one for my office.

When I mentioned this to my wife, I was expecting a "go shove it" instead, I got a "go for it"

I have always planned for some music in my office. As a scientist, I need to keep myself well-read on current articles. I already have a comfy reading chair, and the thought of some nice sounding music should really inspire me to spend a hour each day catching up on the latest.

Anyway, $200-300 on an amp and up to $100 for speakers could be justified. Maybe if the SimpleSE sounds really good, I'll be allowed to keep it at home and invent a way of adding it to my home system alongside my solid-sate power amp (to which I feel some loyality).

Yes, I could build some speakers, if less than $100.

Regards,
Charlie

[tubelab.com]

The SimpleSE and all of my amplifiers were developed and tested with 87db Yamaha NS-10M studio monitors. These are not the most tube friendly speakers in the world. The volume level in my 10 X 11 foot lab is loud. Not extremely loud, but loud. Loud enough to annoy Sherri in the other end of the house with the doors closed. I can't imagine an office where this setup wouldn't generate enough sound. I routinely listen to a TubelabSE with 45's or a low powered SimpleSE with trioded 6V6's through these speakers. Both amps make about 1.5 watts. This is not loud, but adequate for comfortable listening.

Another thing that may be worth investigating, audio pre-amps and CD players etc should not have any DC offset in their output but I am not quite so sure about MP3 players and computer soundcards.

I am now using an EMU 1212 24 bit 192 KHz sound card for most of my music playing. It works great. I have also used a M-audio Audiophile 2496 card. I am slowly ripping my entire CD collection to disc using exact audio copy. The sound is better than my CD player. I have no experience with MP3 players. Many SS amps really hate DC offset, so I imagine any "line output" should be OK. Some headphone outputs may have a small offset without a headphone load, but a few millivolts won't bother the SimpleSE.

If you do decide to build this amp please leave some feedback for the forum and for TubeLab. I think George has sold a few of the boards but have not seen much feedback on the forum or on his site.

Chris: I have sold about 60 boards total. Several people have emailed me saying that they have finished their amps, but you are the only person to send pictures of a completed amp. I recently got a picture of a board fired up and working (trioded 6V6 again), but haven't had time to post it yet.

[cbutterworth]

OK, so how do I order? Who do I pay? How much do I pay?

Charlie

[tubelab.com]

Blank PC boards are $35 and shipping is $8 in the US. You do not have the email feature enabled through this forum, so I can't send you email. Email me and I will forward you the ordering info. My email address is at the bottom of my home page, and I am attempting to include it here.

Never put your email address in text format in a public forum. The evil spam robots will find it and bomb your email box with junk.