59 Bassman preamp into KT88 or 90 or 120 power section?

[jukelemon]

Hi all.

Has anyone experimented with this pairing?

I am curious of the outcome/opinions/etc.

Thanks.

Jason

[jukelemon]

No one?

That is surprising to me.

[Willabe]

Ernie has built bass amps with those tubes but used Sunn and Ampeg pre's.

Ed has used those tubes/tried those tubes but I don't remember in what amp.


                Brad         

[jukelemon]

Thanks Brad.

I didn't think there would be 100's of takers but maybe one :)

Thanks.

[Ed_Chambley]

I am running 2, KT120's in a build.  I am using SS rectification and a LTPI `12Ax7.  My preamp is EF86.  Plate voltage 569 and have used KT88's as well.  I can stick 12Ay7 and and wire it up bassman style if I wanted.

What is it you are wanting to know?  I have a UL design power amp with no negative feedback.  Building for Guitar or Bass or both.  I did both.  

Schematic attached.  I have added a direct line out since.  For guitar it helps to reduce the 3rd and 4th filter to 16uf.  Sort of loosens it up and you really get a great chime.  With the bass and treble backed off it is clean, clean.  Turn them up and and a nice breakup begins.

I really love the amp, but it can get loud.  I use it for outside gigs, however it is great for Bass practice and smaller gigs.  I am pushing to Eminence NEO's 12's in a ported 2. 12 cab.  It is nice.

[jazbo8]

Egnater Tweaker 88 could be close to what you are trying to put together.

[ernie_jr]

the marshalls that were ship to the US used kt 88 (or 6550s) and their pre-amp were basically fender 5f6a.
Look at the schematics to get an idea. all depends on which sound you like.
ernie

[Ed_Chambley]

+1 on the Tweaker 88.  Cannot build it for the sale price.  Still wondering if you are planning Bass or Guitar.  The Tweaker 88 is very Guitar tuned as all Egnater amps are.  The bass never gets deep like a Blackface Fender will.  Even with guitar I do not notice any lower harmonics, but let me say they are great sounding amps for Guitar.

[jukelemon]

Hi all.

Thanks.

I am considering building a Harp amp so figure guitar voicing.

I don't know much about the Egnaters but will take a peek.

Thank you all.

[Ritchie200]

the marshalls that were ship to the US used kt 88 (or 6550s) and their pre-amp were basically fender 5f6a.
Look at the schematics to get an idea. all depends on which sound you like.
ernie

Ernie

The only Marshall that came to the US with KT88's was the Major.  The only other model they built using KT88's was the Park 75 (UK only) which was basically a high plate voltage 50 watt design that gave 75 watts with the 88's.

Jim

[ernie_jr]

Thanks Jim,
That is true, so I guess a better statement would have been an EL34 marshall that has been re-tube with KT 88's
Happy New Year to all,
Ernie

[Ritchie200]

Ernie,

I am pretty single minded when it comes to the KT88...  I have never personally heard the Park 75, but every review and writeup say it is the best sounding thing Marshall ever built.  I would disagree, but you bring up a good point about how great this tube can sound in a typical Marshall layout.  

Juke, KT88's are typically pretty clean and full.  When I think harp amp I envision of a couple of 6v6's run wide open.

Jim

[ernie_jr]

Jim,
I love kt 88s as well. I have a pair of Real KT 88s made in the late 60's that have the sunn label on them. Came with a sunn that was in parts i got on e bay for $150. tubes show signs of very little use and they sound great.
happy new year
ernie

[jukelemon]

Ernie,

I am pretty single minded when it comes to the KT88...  I have never personally heard the Park 75, but every review and writeup say it is the best sounding thing Marshall ever built.  I would disagree, but you bring up a good point about how great this tube can sound in a typical Marshall layout.  

Juke, KT88's are typically pretty clean and full.  When I think harp amp I envision of a couple of 6v6's run wide open.

Jim

Hi Jim.

Yes, 6v6's sound very nice.  However, I am talking about a harp amp that will literally be the loudest equipment on the stage. I need lots of headroom and something that will not easily distort at high volumes.

[Willabe]

However, I am talking about a harp amp that will literally be the loudest equipment on the stage. I need lots of headroom and something that will not easily distort at high volumes.

I'm not sure that's going to work. If you want/need harp loud and clean go through the PA system.

The guy (Mickey Rafael?) that plays harp for Willy Nelson for several decades plays through an old tweed champ miked through the PA for dirty/electric sound and through a mic into the PA for clean/acoustic sound. He could play anything he want's/needs and yet that's what he plays live.  

My 1st band in late high school, I sang and played blues harp. I used a SM57 mic into a Fender dual showmen with 4x12" speakers.

I couldn't get the volume and treble control much above 3 before it would squeal like a stuck pig. At the time I didn't know about using lower gain preamp tubes like 12AY7.

It worked and was very loud, sounded ok but it was not anywhere, as far as tone, that it should have been. Would have been better to get a good/great tone with a smaller amp and boost it through the PA system.


             Brad      

[jukelemon]

However, I am talking about a harp amp that will literally be the loudest equipment on the stage. I need lots of headroom and something that will not easily distort at high volumes.

I'm not sure that's going to work. If you want/need harp loud and clean go through the PA system.

The guy (Mickey Rafael?) that plays harp for Willy Nelson for several decades plays through an old tweed champ miked through the PA for dirty/electric sound and through a mic into the PA for clean/acoustic sound. He could play anything he want's/needs and yet that's what he plays live.  

My 1st band in late high school, I sang and played blues harp. I used a SM57 mic into a Fender dual showmen with 4x12" speakers.

I couldn't get the volume and treble control much above 3 before it would squeal like a stuck pig. At the time I didn't know about using lower gain preamp tubes like 12AY7.

It worked and was very loud, sounded ok but it was not anywhere, as far as tone, that it should have been. Would have been better to get a good/great tone with a smaller amp and boost it through the PA system.


             Brad      

Hi Brad.

Your issue was that you could not drive your amp to natural tube distortion. I have a solution for that which changes the game for harp amps.

I need an amp that can reach/handle a lot of bass and mids at a very high volume.  6l6's can barely do it.

My competitor would be like a Harp King to give you an example of the level of volume to obtain.  They rival Marshal Stacks and mine would do the same.

http://www.kinder-instruments.com/julies6x10.htm

I cannot get that from 6l6's.  The Harp King uses KT 90's and there is a reason for that I think. John could have used any tube he wanted but he chose those because he also found a way to drive a harp amp to greater volumes.

Make sense?

[Willabe]

Your issue was that you could not drive your amp to natural tube distortion.

No the issue was mainly feed back because of too much power and a mic.

But if you've got that worked out your good then.


           Brad