Suggestions on a Bass Amp

[Platefire]

Was talking to one of my old Bass Playing friends today who is getting a custom bass guitar made for himself. He hit me up about building a bass amp---kinda got me off guard!! I him-hawed around and finally ask him what wattage range he would need, he said 100 watts. So I haven't agreed to do it for him yet but did tell him I would research the subject. So I'm open to suggestions. He likes a kind on in the middle sound, not too bottomy and not too bright either. I'm thinking a combo with 1-15--or 2-10, maybe a bassman front end and twin power section. I don't think he would want something very huge and heavy--kinda portable. Platefire

[ernie_jr]

you may want to consider a Sunn power section with SS rec and KT 120's will get you close to 100 watts if you use 400 volt PT

[Dave]

How about an Ampeg V4B. It has some oddball tubes in it, but I think they are triple triodes that could be swapped out for X7s and U7s.

Dave

[tdvt]

How about a single channel B15 but with a with a quad 6L6 output?

That should be close to his wattage requirements, classic bass pre.

I'd probably go 1-15 but also have a 1-15 extension cabinet handy.

The Eminence neo drivers are VERY light (3012, 3012LF,3015,3015LF) but really put out the bass.

Unfortunately, neo speakers have more than doubled in price in the last year, but they're great for old bass-playing guys (myself included). I have one of each, 12" & 15" & while the 12" does WAY better than you'd expect I still prefer the 15". Google "fEarful" for cabinet designs, one could be adapted for a combo.

[birt]

How about an Ampeg V4B. It has some oddball tubes in it, but I think they are triple triodes that could be swapped out for X7s and U7s.

Dave

6K11: can be subbed with one 12AX7 (triode 2 and 3) and 1/2 12AU7 (triode 1)
12DW7: 1/2 12AX7 and 1/2 12AU7

[Platefire]

I did some searches on google and came up with the Ampeg SVT and looked at that schematic---Wow! that's complex. Lot more than I need there.

I'm not familiar with a B15(Ampeg?) and I will have to take a look VB4.

Has anyone on this sight ever built an efficient portable tube base amp? Seems like a 1-15 combo with 4-6L6's would be the ticket. Surely someone has built a 100 watt bassman???? Platefire

[tdvt]

I'm not familiar with a B15(Ampeg?) and I will have to take a look VB4.

Yes, sorry, the B-15 is indeed an Ampeg, actually one of THE Ampegs that made the brand.

It was one of the "fliptops" where the amp chassis was bolted to the removable top panel of the speaker cabinet, which you flipped upside down (placing the amp inside the cab) for transport & flipped it back to the outside to use. A classic recording amp & now pretty pricey for a real one though Ampeg just reissued a "Heritage" version with two different pre's

Octal front-end w/2 6L6's. The B-15N is the most sought after version, they're in Doug's schematic library



Also check out this recent thread:  http://www.el34world.com/Forum/index.php?topic=13272.0

[Platefire]

Believe it of Not!  In the 80's I ran accross one of those in a pawn shop for cheap and didn't know the history on it. I got to thinking about the Ampeg name and went back a week later to check it out further and it was gone. I latter as I got into tube amps realized what a famous amp it was---after the fact.

[firemedic]

I'm finishing up my 100W bass amp build as we speak, my first bass amp.
It's a TR chassis, TR PT, Marshall 100W OT & 4-EL34 output. The preamps are 1- Weber 6S100, modified for bass, and 1-Ampeg B-25b.

I wouldn't bother with an open back combo design, the thing is quite heavy just as a head. I'm going to experiment with a 1-15 closed cab & if needed I will port it.
I'll post when it's done & let you know how it works out. 

[Willabe]

I wouldn't bother with an open back combo design, the thing is quite heavy just as a head.

+1 on what firemedic is saying. It's a bass amp and IMO a separate head _ AND _  a closed back speaker cab would be best for a  _bass_ amp.

An open back speaker cab can not control the speaker cones forward/backwards excursion any where near a closed/sealed back cab.

It's not as problematic with a guitars frequencies, but the low bass frequencies and the power it takes to reproduce them, which/read  how far the "throw" of the speaker has to move, can and will blow up said speaker/s!


                           Brad               

[6G6]

Hey Plate,
The idea of a 100W Bassman isn't exactly new.
Fender did it, themselves.
As you surmised, a Bassman pre with a Twin output.

In real life, bass takes more power than you think.
A simple solution is the Sunn 2000S, with SS recto.

Do check out the fEARful cabinets.
Not cheap, but SO detailed, clear and strong.
I have a 15/6/1 that I power with  Carvin BX 1500 and it isn't at all straining.

[ernie_jr]

+ 1 for the Sunn. They are easy builds at work great for bass
Ernie

[tdvt]

An open back speaker cab can not control the speaker cones forward/backwards excursion any where near a closed/sealed back cab.

Agreed, an open back cabinet won't work well for bass.

But I have built ported cab combos, works better with neo drivers because of the weight savings.

[Platefire]

Ok---a head for use with a closed back cab. I could see me possibly building the head but not the cab because I can only do butt joints not finger joints.

Has anybody built the Sunn 2000S. I downloaded the schematic. What kind of wattage do you end up with 4-6550's. This would need to be a good all around amp for all kinds of music.

[Willabe]

What kind of wattage do you end up with 4-6550's.

Up to 200w's if you push them.


                        Brad     

[ernie_jr]

Plate,
I have built several sunn 200s. same amp, but with 2 6550's and one choke. Very easy to build and very reliable.
A 2000s was "rated" at 120 watts, probably closer to 150, and has very heavy iron, a 200s will get you close to 100 watts if you use a solid state rec and KT 120's. I am building one now with a pentode/ UL switch.
Ernie

[6G6]

Plate,
the fEARfuls use butt joints and PL adheasive to make them both simple and strong.

[Platefire]

Who are the fEARfuls?  I'm pretty much fearful of cabinet work because of my lack of experiance---but have built a few including a closed back--with a removable panel to convert it to open back--all with glued and screwed butt joints.

Ok, I'm kinda sold on the Sun 2000S or 200S--Doug's got the schematics. Is there any board layouts or parts lists already done for those of you building any of these amps? Transformer type references/cost. Platefire

[ernie_jr]

plate,
Trasformers and choke for 200s can be bought as a package from Triode electronics (dynaco Mrk III)
I have made a hoffman board for a 200s, i will draw it out, scan it and e-mail it if you like,
Ernie

[sluckey]

Would you mind posting the Sunn 200 board layout on the forum?

THX... sluckey

[ernie_jr]

not at all, if i can figure out how to get a scan (after i draw it) posted on the board
Ernie

[tdvt]

Who are the fEARfuls?  I'm pretty much fearful of cabinet work because of my lack of experience. 

Go Here...         http://greenboy.us/fEARful/

[6G6]

Thanks for posting the link TDVT.
There is also a 14 part discussion on Talkbass...
if anyone wants to follow through over 14,000 posts to
get the history, development and build details of it.

Another option that would work well is either the Sunn 200S or 2000S
2-15 cabinets.
JBL D140s are pretty sure to be winners...
unless size and weight matter to you.
Also, check out EV TL606s.
These use the EVM15Ls, another proven bass speaker that also weighs a bunch.

The alternative speakers for these would be Emminence 3015s for full range
or 3015LFs plus mids with crossover for more lows and smoother highs,
but that is getting into fERAful territory, anyway.

[tdvt]

You're welcome for the link.

I was on TB alot when that fEarful thread started but that's way more discussing than I'm interested in.

I did, however, build the 12/6 cube & it is now my primary cabinet. I NEVER cared for tweeters in bass cabs but the midrange is actually a good thing, even for an "old school",thumpy player such as myself. I find I dial out alot of the upper end but keep enough for nice clarity & definition.

The fEarfuls are pretty well thought out, VERY light & take alot of power, well worth building.

For more than 20 years I used 2-EVM 15's in TL606 cabs (which I still have & is my reference sound) but now they stay home. The TL's were small & light in their day but I don't care to move them any more. There is a contingent that have made lighter weight TL cabs (thinner ply, more strategic bracing) & loaded them with Eminence 3015's (non-LF version) running them full-range. Supposedly they compare favorably & are similar to the EV's. That is also on TalkBass as I recall.

[SoundmasterG]

The only problem with building a Sunn 2000S clone is sourcing the huge and expensive transformers. A 200S is much more do-able, and Weber does a kit that is very similar to the Sunns and sounds great from all reports. I've got pics somewhere here of a lot of vintage Sunns that I could post so you could see layouts, etc., but honestly I would change a couple things about the vintage layouts....biggest things are to run grid wires differently instead of in the loom, use better grounding, and use grid stoppers. I have an early 2000S myself that I have not overhauled yet, but don't have pics yet. I could take some and post if you really wanted though. Might take me a couple weeks however as I have finals coming up soon.

Greg

[DummyLoad]

my take on a s2000s layout.

attached two .PDF format files; one is PWB wiring and the other is a drill template. layout done on 11"x17" (ANSI B) paper, scale is 1:1, board is 3.125" x 12", turret centers are .315".

use hoffman turrets and board material.

this was drafted with visio 2010; if you'd like a copy of the .VSD files, send a PM with an e-mail address.

--DL