5f6a bassman speakers configuration.

[davebolden44]

greetings everyone. I was hoping I could get a question answered for me today. I have ordered a kit to build my first tube amplifier, as the title says it will be a 5f6a bassman. I was just wondering if instead of using four ten inch speakers if I could just as easily use two as long as the output impedance matches the transformers desired load. I am not very familiar with the four speaker jack configuration and I have done a ton of studying on the subjects of tube amps for many years now but I am still very much a noob. just figure its time to get my hands dirty so I can learn some more. thanks for any insight.

[ampgeek]

Nice choice for a first amp!

There is no reason why you couldn't use two speakers assuming a proper impedance match. You won't be moving as much air as you would with four speakers so it won't be as loud. However, that is why you have volume knobs. LOL!

Not sure what kit you procured...but...all of the ones that I have seen utilize 4 separate RCA jacks (one per speaker) with the output transformer secondary wired in parallel across all four.

Can you shoot us a link to the kit technical information to confirm what configuration it will be coming with?

Cheers,
Dave O.

[davebolden44]

http://www.ebay.com/itm/Tweed-Bassman-T ... 1e97898b1d

got it off ebay, hope I made a good choice. seemed like decent parts for the price compared to others I have seen

[davebolden44]

forgot to mention that I already have a ab763 super reverb which I truly love so I already have the benefit of 4 speakers which is overkill for me anyway. I love the sound of 10s but I just want something more easily transported to the little jam sessions my friends and I have. plus I baby the fender due to it being old so I hate lugging it around anyway

[matt h]

(deleted)

[davebolden44]

there is no doubt about it 15s are great. well I haven't ordered any speakers yet but this is just kinda what I have been dreaming about.

[ampgeek]

Yep! Four RCA jacks in parallel.

I couldn't tell if the output transformer (OT) had multiple secondary taps though.

You might ask the vendor for specifics on the OT (if you haven't already) so you can plan ahead.

Good luck,
Dave O.

[Phil_S]

One aspect of speakers is that the more surface area moves more air. This creates something you can feel as well as hear -- the totality of it. While not all there is to it, at least do some math to give some context to your choices.

We don't need to actually compute the true area. We're interested in the relative differences. For that d^2 will do very nicely.

for 10" use 100
for 12" use 144
for 15" use 225

4 tens = 400
2 twelves = 288
1 fifteen = 225

So, there you have it. the single 15 is nearly as much speaker as a pair of 12's. A pair of 12's isn't that much less than four 10's. The simple truth is that one 15" speaker moves a lot of air. There are sonic qualities you won't get from 10" speakers.

[davebolden44]

I will consider using a 15 in that case.

[labb]

Best check the OT. The original Baseman had an out put imp of 2 ohm if I remember correctly. As to the 15" speaker, I built a Baseman for my son in head config. He originally used it with an extension speaker that was 4 tens. Sounded great...Switched to a single 15" and WoW...I used an OT that had multiple outlets so we did not have the imp. problem.

[Leo_Gnardo]

http://www.ebay.com/itm/Tweed-Bassman-T ... 1e97898b1d

got it off ebay, hope I made a good choice. seemed like decent parts for the price compared to others I have seen

What's not mentioned, does the output transformer have any taps other than the usual 2 ohm tap you find on a tweed Bassman? If you have to match a 2 ohm secondary, think about ordering 4 ohm speakers for your 2x10 combo.

Also, should you go single-15, where do you get one with 2 ohm voice coil? FWIW I like the single-15 idea, just make sure you have an output transformer that can deal with the typical 8 ohm rating first.

[davebolden44]

I am going to find out about the transformer but if I had to guess I would say it is just a 2 ohm tap

[matt h]

(deleted)

[davebolden44]

in all honesty the reason I was thinking tens was because of my super reverb. I play lead the majority of the time and I just thought that they were more articulate across the notes. however I must confess I don't ever remember playing guitar through a 15 so I have no frame of reference to compare. perhaps when I design my cabinet I will give myself options with the room/ speaker baffle so I can experiment with speakers as funds allow. I really just want to make it my knockaround guy for jam sessions so why not personalize.

[davebolden44]

just talked to the ebay guy. 2 ohm tap as I suspected