Bass amp idea

Fender Amp Discussion

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M Fowler
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Re: Bass amp idea

Post by M Fowler »

Boots,

Okay if you can take a look I'm going to collect a few sets of high power transformers and do some builds for local guitar and bass players plus my brother-in-laws bass amp request, he is higher priority. :lol:

I received my Hammond iron yesterday and man Digi-key is down the road not far away, but they sure packed these heavy transformers well.

Mark
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bcmatt
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Re: Bass amp idea

Post by bcmatt »

The YBA3 Custom Special is my absolute favourate bass tone. I saw some band in Vancouver (The Vicious Cycles), and I was blown away by the bass tone. I talked to him after and he has several YBA3s. I had to get one for my bass player (in a bluesy garage-rock band). Found someone selling one for $350, and snapped it up. Has the original Phillips EL34s too.
We've never had any problems for volume and low end in any bar-gig. Sometimes we mic it, but it's never been necessary. At supposedly 100watts it seems about the perfect amount of power to get a bit of grit. Sometimes I wish she could turn it up a bit more without getting too loud.
I think there is a bit of a resurgence in this amount of power for a tube bass amp. You can open them up a bit in gig settings and you actually feel like you get to use the power (unlike an SVT). Ampeg Reissued it's V4B as well. I think in this day and age with big PA systems, it's a great ideal size for a tube bass amp. She ditched her 2009 500W Markbass combo in favour of this for a more vintagey tone and close to the same feeling of power. Of course, it's all about the style and tone it is being used for... I hate those ultra-clean SS bass tones(???); so slick and smooth they creep me out.
Anyways, I just want to encourage you that it's a worthwhile venture. I used to think a big SVT or YBA300 was what I wanted. Naaah!

I also have one of my YGL-3a amps with KT-88s (instead of the usual 6Ca7s) in it and it is also a pretty great tone for bass (at about the same amount of power. I'm not sure the voltage these are running at. I can check if it is of any use to you. I know these Old Traynors use big beefy Hammond Transformers. I wonder if they are the same ones you are looking at...
But seriously, the way Traynor did its biasing might be something worth duplicating. I was thinking of starting a thread about why it is that I have a 1976 Traynor YGL3a with the original English Mullards testing great and still perfectly matched as a quad, and my bass player has the original quad of Phillips EL34s going strong and sweet in her 1968 YBA3. Makes me wonder why the previous owner of my other YGL3a put in KT88s... was he wanting to make a few bucks off the original tubes? Is this due to great tubes back then... or does the circuit have something to do with it? Their bias circuit does look different than what we usually see...
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

Well I have been studying and will refer again to The Ultimate Tone Vol. 3 Chapter 14 Custom Special YBA-3 Traynor build.

I'm using the same transformers and months ago asked for some guidance from a TAG member to reconfirm my choice of transformers which are as follows:

Hammond 378cx power transformer
Hammond 1650TA output transformer

I can run a quad of 6550's or try KT88's. I will recalculate my filament requirement and if needed will add a filament transformer for the preamp tubes.

I'm more concerned about getting all this on a chassis. :lol: Especially filter caps which I'm quite sure I will need to go with axial lead on a turret board rather then can caps. We'll see what happens.

Thanks guys.
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LeftyStrat
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Re: Bass amp idea

Post by LeftyStrat »

I have an old Sunn 200s OT I keep meaning to use in a bass amp, and then I remember helping a bass player by carrying his head in for him, since he had to deal with the two 8x10 refrigerator sized cabinets. That SVT head weighs 80 pounds!

Anyway, for bass, class D is great. I've been thinking about one half of the Alembic F2B into one of these:

http://www.parts-express.com/1x600w-tas ... d--320-311

$84 for 600 watts into 2 ohms, 300 into 4, and 200 into 8. $129 for the power supply. Probably weighs less than the bass guitar.

You could even give him several classic preamps, b15 (james), Alembic f2b (dual showman/ab763), and maybe the Sunn preamp.

But it's hard to compete with something like this for $400:

http://www.tcelectronic.com/bg250-115/
It's never too late to have a happy childhood.
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

I have that 600w Class D amp already and plan to make a bass amp out of that down the road. Got most of the parts just haven't tackled the project yet. :)
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

Bass amp finished, forgot I had a tread on this build so decided to repost sorry for duplicate photos from the other post.
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Bob-I
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Re: Bass amp idea

Post by Bob-I »

That looks beautiful. How does it sound, beautiful I bet, and plenty loud.
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

Yes it sounds good and he has been gigging steady with it.

He made his own head cabinet for it.
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TUBEDUDE
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Re: Bass amp idea

Post by TUBEDUDE »

That's some massive iron alright. Nice cab. What kind of wood did he use? Looks like ash with brown enhanced stain sanded back with a thin dirty blond wash. Lovely!
Tube junkie that aspires to become a tri-state bidirectional buss driver.
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

Not sure I thought he was going to use mahogany but I'll ask him.
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

This bass amp is still Rocking the local venues.

I changed out the quad of KT88 to quad of 6550 tubes and reworked the tone stack and switching.

Just letting everyone know what happens to some of our project amps. I have a lot that just collect dust but others are out making music. :D

Mark
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didit
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Re: Bass amp idea

Post by didit »

Thanks for the update Mark. Good to hear people are actually hearing fine results out of that heroic brute.

Curious how far off KOC YGA-3 did you wander on your final design?

Best .. Ian
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

The board is just a Fender 100w Bassman circuit with deep bass switch.

You know I don't even remember what I used in the PI section for final resistors for the KT88?

The Filter section is just beefed up with 100uf-100uf/500v JJ can caps.

I studied a lot of references, Orange, Mesa, Traynor, Fender, and others.

I will be building my own SVT 300w type amp and will use Heyboer SVT custom replacement transformers so I can have separate winding's for lower screen voltage.
Rockwell666
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Re: Bass amp idea

Post by Rockwell666 »

I use a Sunn model T for bass in a METAL band. 4xkt88's with UL connections and I NEVER get passed 4 on the master with the guitarists both using 100W 6505+ heads.. More then enough oomph to gig with. Nice work!
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M Fowler
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Re: Bass amp idea

Post by M Fowler »

That Sunn Model T has been on my mind too. :lol:

Thanks
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