2w SET amp : OB w/ 15" boomer or TL BOFU ?

[mahleriana]

Hello,
I have two different 2w SET amps (one EL84, the other 45) and a few pairs of fostex 103e or 167e in TQWT, BR or open backs.
For a few years I was happy with it, but recently my ears did some kind of "reset" and lack of bass(OB, BR) or peaks/dips (in TQWT) became really annoying to me. A hint of a real(istic) bass foundation is wanted here...
I don't like BSC as it removes a lot of the SET magic...and efficiency, while Zobel is often interesting in reducing rising frequency response.
I am thinking of two options :
- 103e in OB with eminence Alpha 15a "à la MJK and...XO" : but will a 2w SET be able to produce any kind of bass from these huge bass boomers ?
- or a BOFU (sealed or Nelson Pass TL),
Both options are globally the same price for me due to shipping to France or acces to second hand market. I may even try both.
Thanks in advance for your advice,
Best regards
eric

[woody]

Somewhere in the MJK OB thread Martin says he played them on a friend's tube amp and wasn't verry pleased. I don't rember any details. I built this but used a
different driver in place of the 103's and a 6db/oct xover so you can't realy go by
my results. But having said that they sound a lot better on my F5 clone than my
cheap Antique Sound Labs tube amp.

[ra7]

I think you'll be a little short on power with a 2W SET job, even for the full range driver on an OB. The full range driver may need to be padded down to match the level of the woofer at the low end ~30-40 Hz.

At least 10 Watts.

I don't know why people use tube amps with a high Q driver. A tube amp goes really well with a low Q driver, ala 8" fostex and AN. With a high Q driver, like the Eminence alpha 15, you are much better off with an SS amp having a large damping factor.

If you are going to cross actively and bi-amp, you might get away with the 2W on the full range driver, but I doubt it. I have a miniwatt with 2.5W per channel and it runs out of steam pretty quickly. On the other hand, it does really well when I use it with a voight pipe.

[bjorno]

Originally Posted by ra7

I think you'll be a little short on power with a 2W SET job, even for the full range driver on an OB. The full range driver may need to be padded down to match the level of the woofer at the low end ~30-40 Hz.

At least 10 Watts...

Agree, Here is a suggestion that doesn't need much power but would stay within a maximum requirement of ~10 W:

b

[Godzilla]

I don't think 2 watts will work well at all with the Alpha 15... regardless of the 95db per watt spec i feel you need 100 watts - i use SS with them. The higher power seems to wake the drivers up. Not enough power and they slog along all muddy and lifeless.

The Fostex or the BOFU present a real matter of taste. They sound totally different but good. IMO, if you like a brighter more forward and detailed sound go for the fostex. If you want mellow and relaxed go for BOFU. I also feel if you like to listen critically go for the fostex... you will find they play all the detail. If you don't go for the BOFU... B20, whatever you call it.

[Jim Shearer]

I built an MJK style OB using Fostex FF85K and Alpha 15 with passive XO. I drive it with a Yahama CR-1000 receiver (classic 1970s SS) with great success. I also have a 2.5 wpc MiniWatt amp which I really like on single full range drivers, but not on the OB; 2.5 wpc just isn't enough to get it done.

Cheers, Jim

[Nelson Pass]

How big a baffle can you stand?

[Vix]

Or, said differently:

How big a baffle can you put in the living room without being expelled? (WAF)

By the way, if not OB, have you thought about a BOFU BiB? I seems like it will make music even with one watt...

[mahleriana]

I guess I'll go with a BOFU (B20) pair, trying BIB, sealed and TL or even BR (using chipboard to stay low in price for the moment)... shipping to France is 70 $ !
I tried recently a second hand vintage SS amplifier but i wasn't really convinced with it...so i'll stay for the moment with my SETS until I'll perhaps try one day one of Mr Nelson Pass's designs.
I just can't go too large a baffle : that is with i had thought of the 1.26 qts alpha 15a allowing to stay reasonable (20" large)
Thanks everyone for answers concerning the boomers/SET no future relationship.
Bjorno, I jus't can't read the image you attached...too small !

[rjbond3rd]

Hi mahleriana,regarding Bjorno's image size:

Click on the image, and it will fill the screen in the vertical dimension only. Look in the lower left-hand corner -- there is an icon there to expand the image to its full size.