32 ohm bass amp.

[Tweeker]

Id like to build a moderate budget bass amp for a pair of 16ohm 15s I have. I need 100-200 watts to drive them.

I was thinking an OTL might be tenable with them series connected using 4 6C33Cs in an inverted Futterman. Though I worry about eating my speakers.

Im considering an amp using a dual 115V primary Avel 625VA 25V+25V Toroidal Transformer as the OPT as an alternative.

Any advice, schematics or suggestions would be welcome.

[gingertube]

Heretical suggestion is to run the 2 x 15s in parallel to give 8 Ohms so that they damp each others back EMF and to drive them with a Solid State AKSA 100W amp from here.
http://www.aksaonline.com/

If you want really top HiFi Audio Quality then get the 100W Nivarna Plus Option.

If you want to know what others have said about these amps then look here:
http://www.audiocircle.com/circles/viewforum.php?f=19

Doing the job with tubes is going to cost a heap more particularly if you want it to outperform what the AKSA will do.
Aside: I run an AKSA 55 Nivarna Plus as a reference amp. I have managed to design and build a few amps which outperform the AKSA in most respects except perhaps in bass handling but in every case they cost a minimum of 3 to 4 times as much in parts alone.

Cheers,
Ian

[Tweeker]

Definetly heretical, and why would it be cheaper? Bear in mind I have PSU components coming out my ears. Over 40kJ worth of capacitors, though not so many OPTs. It really doesnt make sense for me to buy any more kits at this point. Im not a sandophobe, but Id like to play with tubes. If I go SS it will probably be a hopped up Aleph 2, which isnt really famous for its bass, but I have the parts.

The drivers in question are Lamdba Dipole 15s, they will be crossed to a mid in a biamp arrangement. I dont think they really require alot of damping factor? I'm thinking about a Visaton B200 for the mid. Instument is upright bass.

[SHiFTY]

Why re-invent the wheel? Use fixed bias push pull 6550s or KT88s. Should be good for 100W with a high enough B+, or you can go parallel push pull for more. Copy a classic fender design (or similar), spend $100 on a large OPT, regulate the screens and preamp power supply.

OTLs are not known for reliability, which is possibly the most important thing you want in a musical instrument amp.

[tomtt]

Originally posted by SHiFTY

Why re-invent the wheel?

OTLs are not known for reliability,
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

they are/have already been reinvented-

http://www.transcendentsound.com

[lndm]

Originally posted by Tweeker
I dont think they really require alot of damping factor?

I agree, and think that damping factor is sometimes weighted too heavily in priority. It may, however, be the reason that valve amps have a stereotypical reputation for wooly bass.

I might think that if your speaker Q is low or your impedance is not very lumpy/steep, you might be OK.