First amp advice for a Newbie

[jonwhitear]

Hi Folks,

I've wanted to build my own tube amp for a long time, partly for the experience of builidng it, partly for the sound quality, and partly for the aesthetics of having something I've built with glowing tubes.

I'm interested in building from a commecially available PCB or kit, as I don't want to make my own board, and point-to-point doesn't really appeal. I've been doing some research on the S5 Electroncs kits and the Tubelab SimpleSE board. I'm aiming to build something including mounting in a chassis for under US$500.

It sounds like the S5 kits are good for what they are, but they are intended as a learning exercise, rather than a moderately serious amp. The Tubelab SimpleSE sounds like a good option. Any other recommendations of boards or kits to look at? My background is more in digital electronics than audio. I can solder and have a multimeter, but nothing more advanced than that.

I'd be connecting my amp up to my ageing Mission 761s (89db, 8ohm) and probably a computer input. I might dig out my old Arcam Alpha CD player as well.

I'm in Australia, so shipping anything heavy from the US is expensive. I've looked at the Edcor transformers, and the shipping cost is nearly the same as the cost of the transformers. Are there any readily available alternatives is Australia?

Thanks in advance.

Cheers,

Jon

 

[dillmeister]

Hi Jon. I have built the Tubelab SE as a first tube project and I can highly recommend it. The instructions are great and it worked the first time it was plugged in. I used all Hammond transformers in mine as that was what was available in Canada. Also George is an active member here on the boards and is always around answering questions.

 

[chanmix51]

G'day mate,

The EL84 push pull from Yves monmagnon is, from my point of view everything a perfect fit:
- no excessive voltage
- enough power to drive most speakers
- fairly cheap tubes and transformers
- it is simple with no extra tuning
- an ECL86 is an ECC83 + EL84 light, it can be replaced by cheap russian 6N2P-EV and 6P14P-EV

Cheers,
Grégoire

 

[spendorite]

As a first timer I think the Tubelab SSE would be a good choice for you.
I built two of them and I can say if you carefully follow the assembly instructions
you should get it right when completed. As its name indicates it's a simple kit
to build.
As you noted the transformers will be your most expensive cost. I went with all
Edcor transformers and even here in Canada the shipping cost was very high so
I can imagine what would be for you in Australia. I highly recommend the Edcors
though. Their cost to performance ratio is very high in my opinion.
You should be able to do it for USD $500 if you can find suitable transformers in
Australia.
If you decide to go with Edcors, depending on your choice of power and output
transformers you should be able to swing it for under USD $600 including the
tubes.

 

[wicked1]

Tubelab and PMillett are the usual recommended PCB options. There are obviously others, but theirs probably have the most info available here..

Tubelab's have more thorough instructions. Pete's sometimes have more options.. maybe that's not true, though, as the Tubelab simple SE has a lot of options too...

Decide how much power you want, and if you want SE of PP, and then choose the board.

I don't know about the transformer market in Aus, but Asia has a lot of great reasonably priced winders. Shipping might not be too bad from there to you. (I'm thinking James or Silk transformers, but haven't actually used either one)

 

[spendorite]

G'day mate,

The EL84 push pull from Yves monmagnon is, from my point of view everything a perfect fit:
- no excessive voltage
- enough power to drive most speakers
- fairly cheap tubes and transformers
- it is simple with no extra tuning
- an ECL86 is an ECC83 + EL84 light, it can be replaced by cheap russian 6N2P-EV and 6P14P-EV

Cheers,
Grégoire

That looks line a nice simple low priced kit to build for those with a little bit of
experience.
As a person with no experience he would have to learn to translate a schematic to
practical wiring. Even with the photo this would be a challenge for a somebody new to this.
He also indicated that he wants to avoid point-to-point wiring so that kit may
not be suitable for him.

 

[Eli Duttman]

I'd be connecting my amp up to my ageing Mission 761s (89db, 8ohm) and probably a computer input.

Be very cautious in your selection process. Applying Paul Joppa's 102 dB. rule to the claimed 89 dB. sensitivity suggests upwards of 16 WPC being in order. If the Mission speakers exhibit substantial dips in their impedance curve, they should be regarded as being 4 ohm and that requires the sensitivity be reduced to 86 dB.

IMO, SE is not a good idea, given the Mission speakers. Look for a push/pull PCB that can be populated with "hefty" tubes, like the 7591, 6L6, EL34, and KT88. "Flea" power SE amps mate well with speakers whose sensitivity is upwards of 94 dB.

 

[spendorite]

Be very cautious in your selection process. Applying Paul Joppa's 102 dB. rule to the claimed 89 dB. sensitivity suggests upwards of 16 WPC being in order. If the Mission speakers exhibit substantial dips in their impedance curve, they should be regarded as being 4 ohm and that requires the sensitivity be reduced to 86 dB.

IMO, SE is not a good idea, given the Mission speakers. Look for a push/pull PCB that can be populated with "hefty" tubes, like the 7591, 6L6, EL34, and KT88. "Flea" power SE amps mate well with speakers whose sensitivity is upwards of 94 dB.

I agree. He may be okay with the SSE and his speakers though but it depends on what
type of music he listens to, how loud and the size of his listening room.

My speakers are Spendor SP1 which are rated at only 88db but presents an
easy load for vacuum tube amplifiers. I listen to mostly jazz and classical music.

For small jazz combos and small scale classical music in my average sized room it
gets loud enough for me with the volume pot at the 11 o'clock position.

For rock and heavy metal music especially at loud levels the SSE would require speakers
of much higher efficiency.

 

[jonwhitear]

Thankyou all for your advice.

I listen to rock, pop, folk, and some classical. The biggest room I'd use this in is about 7m x 5m (about 23' by 17') with a wooden floor. Listening volumes would be moderate.

I'll have a look at the Tubelab SPP as well, though going by the Tubelab site that seems to be less flexible that the SSE with respect to the type of tube - sounds like it's really aimed at using EL84s (not that that means much to me, I'm afriad.)

Cheers,

Jon