HoSo56 amp

[tubenit]

DaGeezer has a pattern of coming up with great amp ideas!    The thread on this amp is here:

http://www.el34world.com/Forum/index.php?topic=5901.0

Thanks DaGeezer for all you contribute to the forum!!

With respect, Tubenit

  Some of the files on this thread may open and some may not. IF one doesn't open then follow the advice below, please.

You can find most of these schematics in the "Broken Links" file.  Write down the name of what you are looking for and then click on to this Broken Links file list.   Use the list on the "Broken Links file" to hopefully find what you are looking for:

http://el34world.com/Forum/index.php?topic=17420.0

[Geezer]

Here's a few "notes" for those of you who may want to build this amp:

1 - I would use a larger value (1Meg Audio) for the MV, as the 500k attenuates the output a good bit, even at full up position. OR, put an on/off switch in there, so you can take it out of the circuit when you may want to.

2 - A larger coupling cap into the PI is OK & desirable. I have a .0047 shown, but have subbed in .022 & .047 without any blocking distortion or ill effects, & it fattens up the tone even more.

3 - Try different values for the "smoothie" caps across the plate resistors (probably lower, if you want more of the Voxy "chime")

4 - And finally, DO build it! It's a fantastic sounding, touch responsive amp. Wonderful overdrive at reasonable volumes.

Once again, special thanks to Heinz for all his help in designing (reverse engineering) the circuit to "sort-of" emulate the 65amps SoHo.

EDIT:  This is a 3-10-09 schematic change by DaGeezer.   He is now using a 2.2M for the Mstr Vol and commented that with it    
           turned up ....... the volume is comparable to no Mstr Vol and that it has a nice smooth taper to it.

[tubenit]

OK, this is my version of DaGeezer's  HoSo 56.  I just calling mine the 56T  (t for Tubenit).  My voltages with the 5Y3 are on the schematic.  See my post on Tweaks below:

DaGeezer, you have come up with another VERY cool sounding amp!  It does sound similar to those video/audio clips. It is a pretty diverse amp. Engage the NFB and leave the other two boost switches off and it has a nice clean tone. Disengage the NFB and engage one of the boost switch, it sustains and overdrives very nicely.

Super touch sensitve and really really nice harmonics with a pretty smooth sounding overdrive.  The amp does not have any more hiss than the Little Wing or the Carolina Blues Rocket at the same volumes. I like a quiet amp and the hiss is not a problem for me at the levels that I will play it at with a band.

I view the NFB switch a must on this amp for me. It offers another very very nice tone and the NFB completely eliminated the hiss making it super quiet even at reasonably loud volumes. It still left the amp very touch sensitive with nice harmonics.

I like the PAB switch with a paralleled .001 on the treble pot cap. That works perfect for me!  Without the .001 it was waaayyy too trebly. The .001 leaves it with about the same balanced tone (as with the tone controls) but boosted.

I choose a 2.2uf instead of a 25uf to be switched in on V2-3 cathode. Sounds smoother/better to me with less grit for my taste. 

I actually like it better without the crossline master volume engaged. But the mstr volume does give it another sound which makes it more compressed sounding and you can control the volume.  I'm using one of Hoffman's 1M pots with the spst. I suspect that I will probably play it not engaged more than with mstr volume.

This is another feather in the cap of a genius (Geezer not me) in my book!!

EDIT: HotBluePlates gave me a capacitor substitute box that sure helps when tweaking amps!  I changed two caps on my 56T.  The paralleled treble cap is now a .002 instead of .001. And the cap going into the phase invertor is now a .01 instead of a .0047. This allowed more mids and more overdrive and a smoother sound to my ears. It will get the Billy G sound with the PAB switch on.

Edit #2: One of my 5879 tubes went microphonic on me. I devised a socket damper using some a heat resistant silcone hot pad like one would use cooking with an iron skillet.  It completely isolates the socket from the chassis. I used a penny to cut around for the hole. This works fantastic in eliminating microphonic for this pentode tube.

Edit #3:  I tried using .02 instead of .01 coupling caps between the LTPI and the EL84'. I like quite a bit better and it allows more mids thru so I changed them to .02.  The .01 caps are more chimey and Vox sounding. The .02 captures a little more Marshall tone, IMO.

Thanks, Tubenit

[Geezer]

Finally, the "Real Final" (Geezer) version of this amp....this is how it is right now & as far as I can tell, there are no further improvements I can make. It's perfect!

Enjoy

[CraigB]

Hi all, here is a board layout for the 30w 4xEL84 version I built for myself (a slight departure from tubenit's excellent Vox-style terminal board layout) based on da Geezer's final schematic from 3/18/09.  I left the power rail transistor resistance values blank, as you will most likely need to tweak these to get in the ballpark depending on what power transformer you use.

Anyway, this configuration works well and is reasonably quiet and no squeals if you follow the most basic lead dress.  Also, all that is needed to adapt this to the 2xEL84 version is delete two of the 100R screen resistors for the power tubes and use a suitable power tube cathode resistor value, i.e., 120R, 130R, or 150R.

Also note, due to very tight space requirements, I used radial caps right on the board (3 inches wide x 12 inches long), but most people will probably opt to use a multi-cap can or a separate or longer board for axials.  Also, I used V2's socket to mount the 100K/250pF which gave me a little extra room on the board so things weren't crammed too close together.

Do plan on building these guys' design.  It really has an incredible range of tones.  Thanks - Craig

[tubenit]

I love my 56T & continue to get nice compliments about it. My son recently played all 3 of my amps and picked the 56T as his favorite.

However, I miss having reverb. The D'Lite type reverb I use adds some richness and warmth and dimension to my ears.  But ........ my chassis doesn't have room for another tube to add the verb. I use a delay pedal with the effects loop.

Anyhow, for those of you who are building from scratch ........     Here is a reverb version of my amp. I haven't built it but this type of reverb has been successful on every amp I have tried it on.  A note on how I drew it:  I noted that the reverb trannie & the reverb tube pin 6 (plate) hook up to node C on the B+ rail.  What I might consider doing it mount a terminal strip next to the tube socket and hook up the reverb trannie and pin 6 to a terminal (non grounded of course) that connects to node C. That way you won't need more space on the layout board.

*EDIT: I crammed another tube in and used a terminal strip next to it and built the 56T with reverb.  I ended up using a 500k pot and a 680k resistor for the dwell.   It sounds fantastic to me. I had no issues at all with oscillation even with the reverb dialed to 10. It has enough reverb for me on 3-5.

EDIT 6/9: I tried using just the pentode of a 6BM8 instead of EL84's and like it better. The EL84 is brighter, has more chime, but has more grit in the distortion to my ears.  The 6BM8 does not have as much distortion or chime but it is equally expressive. I think the 6BM8 has comparable sustain and has more warmth.

While I used only the pentode of the 6BM8 with a 12AX7 LTPI, you could build this using the 6BM8 triodes for the LTPI & I drew this schematic and layout using the 6BM8 triodes.  

7/6/09 update:  I changed the 470k paralleled by the .01 cap to 100k paralleled by the .01 cap.  I used a resistor box to try different values and found that to be the best to my ears. It allowed a little more expressiveness in the playing. That resistor/cap is between the cathode follower and tone stack.

With respect, Tubenit

[tubenit]

I added a VVR variable voltage regulator to the 56T reverb. Here is the final schematic. I VVR'd both the power amp and phase invertor & continued to use the Marshall type pre-LTPI master volume.

I redrew the layout with the reverb on the tag board which is how I would build it from scratch. I do recommend using the NFB switch which gives a choice of two useful tones.

With respect, Tubenit

[DummyLoad]

i wonder how it would sound with a cathodyne or paraphase PI....

[tubenit]

I have built an amp and kept everything the same as much as possible comparing the LTPI and cathodyne.

The result is that all 3 of my amps have LTPI.

Best regards, Tubenit

[LooseChange]

The file: 56T Reverb.sch does not want to open.

I would place the reverb after the effects loop.  It's nice to get a bit of delay or chorus in front of the reverb.
How does the reverb sound done like this??

[tubenit]

I think the reverb sounds absolutely superb on this amp!  I played it without reverb for a while and really missed the verb.  I crammed it into a corner of the chassis using terminal strips & it sounds super sweet to me. Plus the amp remained quiet at idle.

This is a small amp with only a 10" Ragin Cajun & 7-9 watt 6BM8's and it sound big to me. Add a digital delay and it sounds huge.  I love it. Highly recommend the reverb. It gave this amp a much richer lush tone. I've gotten some very nice comments on this amp from the band I sit in with (& the sound guy).

The SCH file opened right up for me. Not sure what the problem was?

EDIT: reverb needs a 500p-.001 range cap into the dwell pot.

With respect, Tubenit

[Fresh_Start]

Tubenit - I'm sure you've tried different insertion points for the reverb and the effects loop.  What is the downside of putting both between the Treble pot and the Trim pot?

Cheers,

Chip

[tubenit]

Don't know about reverb insertion there?  This is actually the only way I tried it and it worked beautifully so I didn't experiment any further.

I have a capacitor substitution box and I have experimented for hrs tweaking the 56T and then trying it with the band to see how well it sounds and cuts thru. This is the final tweaked amp. Note that I put in a 50uf/50v cathode cap with the 6BM8 pentodes and increased the V2-3 cathode cap to 4.7uf

With respect, Tubenit

EDIT:  Based on some chassis photos, I've added two more schematics to consider. One drawn by Heinz.

[tubenit]

OK, I tried a 56T with EL84's, 6BM8's and 6AQ5's. I made the least amount of change possible trying each tube. The EL84 was sort of 25%Marshallish/75%Voxish.  The 6BM8 was more like 75%Marshallish/25%Voxish and did the best getting the ZZTop sort of sound with the squawks and sustain.  

I'd have to describe the 6AQ5 as sort of a mix of Fender/Vox/Marshall. The bass and mids are clearer sounding, still has some the chime/jangly Vox (unlike my 6V6 amps) and with the overdrive cranked sounds more like a Marshall/with a dash of Fender mix. I've played a number of 6V6 amps and I think the 6AQ5 has more chime than a 6V6 does. I think the 6AQ5 is the best of the 3 for the kind of blues I listen to.

All three tubes allow the 56T (my HoSo56 version) to still articulate well and it remains a very very expressive amp. I can't say one tube made it a more expressive amp then the other. My least favorite is the EL84 which was brighter with the most chime. Cranked, perhaps the 6BM8's are my favorite for playing lead and they would hold a note into feedback. I think the clean tone of the 6AQ5 are warmer and more balanced to my ear. The 6AQ5 also has a very smooth overdrive. However, it has less sustain than the 6BM8 or EL84.

Just my take on what I'm hearing.

Edit: more I play the 6AQ5 version, more I like it. These tubes are staying in. I increased the post LTPI coupling caps to .02, increased 6AQ5 cathode cap to 18uf and then added a 180p "smooth cap" just prior to the .01 cap into the LTPI.  I did try increasing the .01 into the LTPI to .02 but it lost some expressiveness so the .01 stayed in. The 180p cap was perfect and simply muted those really high chimey frequencies. The amp still has plenty of chime and expression to my ears.

with respect, Tubenit

[Geezer]

Another option for the HoSo......channel switching.

Thread is here>  http://www.el34world.com/Forum/index.php?topic=10933.msg100602#msg100602

[John]

I'm getting ready to make a parts list for your amp, Geezer and Tubenit. I'm really excited about it. It's simple enough for my first build (I think) but involved enough to be a challenge. Plus when I'm done, I'll really have something! Thanks to both of you and everyone else on this forum for being so willing to share your ideas, work, schematics, advice and everything else. I'm sure I'll have questions along the way, but fear not: Google is my friend. I'll only ask when I'm really stumped. Cheers!

[Geezer]

Hey John, it really is a great amp. With a boost pedal or OD in front (I really like the el cheapo Digitech Bad Monkey) it can get about any tone you want.

If at all possible, I suggest you build it with the relay switching, but if not, you can still get the same tones by adjusting the controls & maybe adding some switches for the cathode bypass caps & mid boost.

Also, the pentode is very sensitive to voltage and to the plate resistor value....if there's not enough headroom, lower the V1 plate resistor slightly, and reverse if you want less headroom/more touch sensivity.

G

[John]

Thanks for the advice! Yes, I'm planning on putting the channel switching in, as per your last schem - 2/3/11 I think it is. I have to do a little more research to make sure I hook up the relays properly. Also, good point about the voltages; I'm going to try really hard to get them as close as possible to what you have marked down. I'll be using the 18W tranny set from Doug, so that should help too.

Thanks again!

*edit* right now I rely on footpedals for all my OD tones, plus I'm running the cheapy Behringer digital reverb pedal ($35) that really sounds good to my ears through my old Harmony. I'm looking forward to being able to dial in 2 different settings through the amp itself though, and getting my gain/OD out of that.

[John]

Just placed my first parts order! Mostly got the power supply stuff and the board and turrets. I figure I'll place only a dozen orders before it's done anyway.

*edited* It's now 20 minutes later and I have an email saying it's boxed and shipped. No way!

[Geezer]

WAY!  After all, it's Doug Hoffman.........

[John]

Okay, putting holes in the chassis right now, but have a question about the dual gang pot for the PPIMV. First, it is audio taper, correct? And, where do I find them? I tried turretboards, mojotone and AES (although I could have just missed 'em).

 Or, could I use the 1meg that Doug sells and use say, a 1.5meg resistor instead of the 2.2?
Or is that just stupid and makes no sense at all?

One more- The T-5879 that AES sells is good for the first preamp, correct?
http://www.tubesandmore.com/scripts/foxweb.dll/catalog@d:/dfs/elevclients/cemirror/ELEVATOR.FXP?PAGE=SUBCAT&SEARCH_TREE01=ZCATALOG&SEARCH_TREE02=2009010

Thanks in advance!

[JBP]

Hi, I built an 18 watt lite II and have been tweaking it for awhile (cascade,plexi,so on). I'm ready to try something else and would like to build the 56T. Can I use my 18 watt iron ? pt is 290-0-290 with 357v out of  ez81 recto. I have a Hall vvr installed, will this work as drawn in 56T schematic?  Thanks, Jeff

[tubenit]

Hi, I built an 18 watt lite II and have been tweaking it for awhile (cascade,plexi,so on). I'm ready to try something else and would like to build the 56T. Can I use my 18 watt iron ? pt is 290-0-290 with 357v out of  ez81 recto. I have a Hall vvr installed, will this work as drawn in 56T schematic?  Thanks, Jeff

I think using the Hall VVR & your 18 watt iron, that you can dial down the plate voltage on the power tubes and be just fine.

with respect, Tubenit

[JBP]

Thanks for the response tubenit. I'm trying to get this all sorted out in my head before I power up the soldering iron and I've only been at this a few months. Their are holes in my tubeamp knowlage/understanding so please expect the occasional odd question. Looking through the schematics and revisions I see the PI as either 12ax7 or triodes of 6bm8. I will be using the 6bm8 tubes and was wondering which PI was better. 6bm8 PI makes available a 12ax7 for possible  reverb driver ? Thanks, Jeff

[surfsup]

RE: 56T version, I am thinking of doing this version with SS instead of 5Y3 and created an XLS BOM sheet for it so far.

For changes,

1) I assume my fuse should be 1A slo-blo instead? I don't see how the amp would ever blow a 2A fuse unless the B+ shorted to ground. Also, the NFB RC to gnd, that's a 1k8 or a 1k0? hard to read the gif (I dont have *sch software).

2) There are quite a few 220k to ground in the PA. I believe I would only need the first one. The caps will still drain (they do on my other amp with similar VVR configuration). Why are there two more on the PA section and one more on the PreA section?

3) The NFB switch is listed as a DPDT. Shouldn't that be a DPST? Perhaps the choices of DPST switches are limited...

4) (edit) forgot to ask, is there a 7pin socket type that fits in a noval chassis hole in case I want to go 9pin later in the pA and swap em, I don't want to start drilling into a chassis already "built" with components. thx as I am not aware of one.

[sluckey]

1) I assume my fuse should be 1A slo-blo instead? ... Also, the NFB RC to gnd, that's a 1k8 or a 1k0?

Give the fuse a try. The resistor is 1.8K

2) There are quite a few 220k to ground in the PA. I believe I would only need the first one. The caps will still drain (they do on my other amp with similar VVR configuration). Why are there two more on the PA section and one more on the PreA section?

See the additional isolation diodes? Those will prevent the downstream caps from discharging through the first 220K resistor.

3) The NFB switch is listed as a DPDT. Shouldn't that be a DPST?

No, it should be a SPDT. Or just use half of a DPDT.

4) (edit) forgot to ask, is there a 7pin socket type that fits in a noval chassis hole in case I want to go 9pin later in the pA and swap em

Weber sells (or used to) an adapter ring that allows a 7 pin socket to mount in a 9 pin hole.

[surfsup]

Which reverb tank/tranny are you guys using for this? tia

[sluckey]

Doug's 4AB3C1B or 9AB3C1B

[tubenit]

is there a 7pin socket type that fits in a noval chassis hole

Yes, when I did a 6AQ5 version, I used a 7pin  tube socket that fit right into the same 9pin hole perfectly. My guess is that I got it from Antique Electronic Supply but don't remember for sure?   Part # P-ST7-814

Looks like this mounts into a 7/8" hole same as Hoffman's 9 pin ceramic socket.

With respect, Tubenit

[surfsup]

FYI those are 7/8" drill centers the hole is 5/8" so its not the same. The noval hole is 7/8 so the drill centers are the same dia and it won't fit.

I'll keep looking...

[tubenit]

I know I converted from a 9 pin 6BM8 tube to a 6AQ5 withOUT changing anything about the punched hole IIRC. Whatever aluminum base there was to the ceramic 7 pin tube socket worked with the same exact hole as the 9 pin tube socket. Just not sure what 7 pin socket I used? I thought it was AES?

With respect, Tubenit

[arjepsen]

Did anyone build the hoso56 with an ef86?
I'm wondering about the tonal differences to the 5879, and if anyone played around with component values for an ef86 instead.

[tubenit]

Did anyone build the hoso56 with an ef86?

Not to my knowledge?  You can use a 6AU6 or a 5654 pentode instead of a 5879.

with respect, Tubenit

[arjepsen]

I've been studying the pictures linked in the long hoso thread. It seems to me that the resistor coming of the cathode of the CF is not 100k, but instead 180k (comparing the color rings to the other 100k resistors close by).
I'm a little vague on the theory here - what would this difference do to the sound and/or gain?

[Geezer]

Not sure what value is in mine (& the newer variations) exactly, but you can (and should) try different values to see what you like best....very easy to do.
The basic idea is that higher or lower values (from the standard Fender/Marshall 100k) change the bias/gain of the stage, and allow more (higher value) or less (lower value) gain or signal to pass to the next stage.
I have used from 56k to 150k there, depending on the amp (using my ears as a guide).

$0.02

G

[tubenit]

Check for errors!  Compare schematic with layout.  IF there is a discrepancy, go with the schematic.  Look up the 6BM8 pin outs on the data sheet.

As far as the passive effects loop,  I have found a Moen Pretty Dolly delay,  a Boss digital delay and a MXR Carbon Copy and a Digitech RV-7 reverb to all work pretty well with this.

With respect, Tubenit

* I added another one but with active FX loop

[tubenit]

Here is an EL84 version of the HoSo56 "the minimalist" with active FX loop.  I have NOT built this version but did a 6BM8 version that is similar.

CHECK for ERRORS!  Compare schematic with layout,  IF there is a discrepancy ……….. then go with the schematic.

With respect, Tubenit

[tubenit]

Some SCH files in this thread are not opening.  I'm reposting my 56T which is the reverb version of the HoSo56. 


Check for errors!  Compare schematic to layout, if there is a discrepancy ........... go with the schematic.


With respect, Tubenit