Will the S.E.X. drive the BK-20 speakers from Madisound?

[JWeldon]

Hello to all,

I'm thinking of jumping in to the Bottlehead and DIY speaker pool and thought I'd ask for some advice about which direction to go.  A little background about me seems to be a good place to start, so you know where I'm coming from. 

I've heard a few high end systems, but have never had one myself, and have never built a kit such as offered here (have done some electrical projects, but nothing like this).   Last fall I bought some Sennheiser HD-600 that I use with a Schiit Fulla2 (I travel a lot for work and this makes a pretty good travel kit).  Most recently I've been listening to mostly jazz (on vinyl & streaming), but also enjoy Rock, Acoustic and occasionally some classical.  I also like to stream Radio Paradise, Tidal, and Spotify.

My living room is approx 15-25 with hardwood floors and the usual furniture, curtains etc.  Currently running an Onkyo 2 channel receiver into some old Bose 2.2 that my wife had from her college days.  Sounds pretty lacking...

So rather than spend a bunch of $$$ on an new amp, and more $$$ on speakers to upgrade my system, I'd like to try my hand at building one. I'm thinking a S.E.X. or Stereomour II and paring it with the BK-20 (Fostex FE208ez) kit from Madisound.  I have two concerns though that I was hoping you all could help me figure out.

1. I'd prefer to build the S.E.X. amp mainly due to the headphone jack (I use the HD-600's at night when kiddo is asleep), but it's also significantly less $$ than a Stereomour, and as I understand it, easier to build (this will be my first build).  But when I consider the speaker part of the equation I wonder if I should just go big and go for a Stereomour first.

2. So will a S.E.X. drive the Fostex kit enough to fill my room? and will it provide enough bass?  I'm really not a bass head, but I don't want killer mid's & high while lacking in the low end department.  Also, if I need to add a sub later, will that pull too much power from the S.E.X. amp? (or how do I run another amp just for the sub and control volume from the S.E.X.?)

I've seen the SEXy speakers recommendation and wonder if that might be a better way to go, but am a little concerned that it might not be the right fit for my room size.  I've read about the Frugel horns, and super tweeters and bucket subs...I'm up for taking a chance on a system, just don't want to put all the effort in to building it only to find I need to start over again later.

Thanks, and Cheers!!

-Jeff

[Paul Joppa]

As a rough approximation, I think 102dB is enough for "most audiophiles, most of the time." For more casual listeners, I think 96dB is usually adequate. Headbangers who want to reproduce rock-concert levels will want a lot more, maybe 112dB (?). That FE-208EΣ is rated 97dB/w/m, so with 2 watts (SEX amp) it will make 100dB before running out of steam; Stereomour will give 103dB. Both are SETs, which overload very gracefully - that gives you maybe 3-6dB more real-world capability than the numbers indicate. So I would expect the SEX to be adequate.

As for bass, both amps use the same output transformer and plate choke, and have the same bass extension. (SEX operates at twice the impedance level of Stereomour, so the transformer can handle half the power). Full power is available down to about 25Hz in both cases.

[fromnowon]

It would be fun to build that folded horn kit . . . I've looked at those too!

Currently I have the Tang Band W8-1772s in MLTL cabinets based on plans that I bought from Bob Brines' before he closed his business.  It is amazing how good the mids and highs can be from full-range speakers, and the imaging.  I use subwoofers with them as bases to sit the cabinets on, so the speakers are at ear level.  The plans came with baffle step correction network layouts and I built them but haven't been using them because I like the speakers as they are, directly wired to the amp.

I don't have a S.E.X. but I think full-range speakers are cool and of course, they are very efficient.  I'm really glad I took the plunge into full-range, FWIW!

[Paul Birkeland]

I, long ago, had the SEX amp on a pair of BK-20 speakers and was not disappointed with the playback level available with the combo in a medium size room.

[JWeldon]

As a rough approximation, I think 102dB is enough for "most audiophiles, most of the time." For more casual listeners, I think 96dB is usually adequate. Headbangers who want to reproduce rock-concert levels will want a lot more, maybe 112dB (?). That FE-208EΣ is rated 97dB/w/m, so with 2 watts (SEX amp) it will make 100dB before running out of steam; Stereomour will give 103dB. Both are SETs, which overload very gracefully - that gives you maybe 3-6dB more real-world capability than the numbers indicate. So I would expect the SEX to be adequate.

As for bass, both amps use the same output transformer and plate choke, and have the same bass extension. (SEX operates at twice the impedance level of Stereomour, so the transformer can handle half the power). Full power is available down to about 25Hz in both cases.

Thanks for the technical info Paul.  That completely alleviates my concerns about whether those speakers will match well with the SEX amp to fill my room.  I appreciate your reply!

[JWeldon]

It would be fun to build that folded horn kit . . . I've looked at those too!

Currently I have the Tang Band W8-1772s in MLTL cabinets based on plans that I bought from Bob Brines' before he closed his business.  It is amazing how good the mids and highs can be from full-range speakers, and the imaging.  I use subwoofers with them as bases to sit the cabinets on, so the speakers are at ear level.  The plans came with baffle step correction network layouts and I built them but haven't been using them because I like the speakers as they are, directly wired to the amp.

I don't have a S.E.X. but I think full-range speakers are cool and of course, they are very efficient.  I'm really glad I took the plunge into full-range, FWIW!

Yes, I think it would be a fun build too!  I like DIY stuff so the thought of building a great sounding system really appeals to me.  Sounds like you've been successful at doing just that!

Are your subs powered?  I've been trying to read up on sub connections, and am a little stumped at how to wire in a separate amp to power a set of passive subs.  I'm hoping not to have to go that route tho...

[JWeldon]

I, long ago, had the SEX amp on a pair of BK-20 speakers and was not disappointed with the playback level available with the combo in a medium size room.

Hey thanks for the reply Paul,  sounds like the combo will provide sufficient volume.  Any recollections of the sound quality/chachteristics?  I know the drivers take a long break in period, and the mids can be a little forward.

thx

[Paul Birkeland]

Hey thanks for the reply Paul,  sounds like the combo will provide sufficient volume.  Any recollections of the sound quality/chachteristics?  I know the drivers take a long break in period, and the mids can be a little forward.

I didn't have nearly enough room treatment to properly use the BK-20 at the time.  For the cost of the kit, I believe you can recoup nearly your entire purchase selling them later if you don't like them (provided the build goes well of course). 

[fromnowon]

Yeah my subs are 10" powered, these:
https://www.parts-express.com/dayton-audio-sub-1000-10-100-watt-powered-subwoofer--300-628

I followed advice here for the connections:
https://bottlehead.com/s-e-xy-speakers/

Even though I didn't go this route, I did think it was nice that Tang Band put plans for some full-range enclosures here:  http://www.tb-speaker.com/  (SUGI-19)  They look challenging to build but would be fun to try.