How much is using speakers to build a shelf going to effect their

If they were a decent pair of well build speaker before, the size of the cabinet would of been tuned for the specific driver.
Volume and port sizes (size and depth) matter (look up diy speaker building/golden speaker ratio/port calculations etc)
It's quite possible they will sound like absolute shit.

Any shelf you tack on to the speakers will vibrate and muddle and muddle the sound, even the speaker itself has to be braced properly and made of particular sorts of wood.

Test it. Get a tray between them, stack up some books on it, and hear if the speakers still sound any good.

If you're asking this question then you were never going to have them properly setup for your room anyway.

>>52350605

sell your old speakers

get some good ones (not necessarily new, so not necessarily expensive) that fit on the bookshelf

It's very possible that there would a significant resonance frequency that would sound gross. You can test your luck though.

>>52350605
speaking of speakers, what are some good brands for speakers?

>>52352602
There is none. You have to go by model

Get cable raisers and crystals and you should be fine, OP

What if OP acoustically isolates the speakers from the rest of the shelf with sound deadening material?

>>52353323
That's not really true, for example Sonus Faber only makes legit speakers, no HTIB or multimedia shit like many previously respectable brands (B&W, Focal etc) have been pushing lately.

Whether they're the best bang for your buck is another question altogether.

>>52350605
Old stereo speakers would probably be designed to stand in free space. When you put a speaker up against a wall, on the floor, in a corner, in a cabinet, etc, you're making the bass and midrange louder than what was intended. This is because treble is directional like a ray, and bass is less directional or omnidirectional and behaves as pressure. Sound pressure that would normally fill the air behind the speaker is instead sent to the listener. Basically the more you cover the speakers, the less accurate they will sound.

Resonances also decrease sound quality. You'd want something to put in between the speakers and the shelves like >>52355152
said so you aren't transferring energy to them, especially to the point of vibration.

Also I'm confused, is this going to be a 29 inch tall shelf? Don't place these on the floor. The tweeters are ideally at ear height because of the directional qualities of treble. This is why normal people but speakers on shelves instead of shelves on speakers.

>>52351139
Old speakers are great and it would probably cost a lot of money to buy a modern equivalent.

But if the speakers are nearing 30 years old, the capacitors need replacing to sound their best.